simulated planetary atmospheres: Topics by Science.gov

Sample records for simulated planetary atmospheres

Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1987-01-01

Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and Earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorping properties of potential constituents is available. The use of theoretically derived microwave absorption properties for such atmospheric constituents, or laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurement of the microwave properties of atmospheric gases under simulated conditions for the outer planets were conducted. Results of these measurements are discussed.
Laboratory measurements of microwave and millimeter-wave properties of planetary atmospheric constituents

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1989-01-01

Accurate data on microwave and millimeter-wave properties of potential planetary atmospheric constituents is critical for the proper interpretation of radio occultation measurements, and of radio astronomical observations of both continuum and spectral line emissions. Such data is also needed to correct for atmospheric effects on radar studies of surface reflectivity. Since the refractive and absorptive properties of atmospheric constituents often vary drastically from theoretically-predicted profiles, especially under the extreme conditions characteristic of the planetary atmosphere, laboratory measurements under simulated planetary conditions are required. This paper reviews the instrumentation and techniques used for laboratory measurement of the refractivity and absorptivity of atmospheric constituents at wavelengths longward of 1 mm, under simulated planetary conditions (temperature, pressure, and broadening gases). Techniques for measuring both gases and condensates are considered. Also reviewed are the relative accuracies of the various techniques. Laboratory measurements are reviewed which have already been made, and additional measurements which are needed for interpretation of data from Venus and the outer planets, are highlighted.
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1992-01-01

Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. The goal of this investigation was to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, P. G.

1986-01-01

The recognition of the need to make laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressure which correspond to the altitudes probed by radio occultation experiments, and over a range of frequencies which correspond to both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. Construction was completed of the outer planets simulator and measurements were conducted of the microwave absorption and refraction from nitrogen under simulated Titan conditions. The results of these and previous laboratory measurements were applied to a wide range of microwave opacity measurements, in order to derive constituent densities and distributions in planetary atmospheres such as Venus.
Laboratory Evaluation and Application of Microwave Absorption Properties Under Simulated Conditions for Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1997-01-01

Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurements completed under this grant (NAGW-533), have shown that the opacity from, SO2 under simulated Venus conditions is best described by a different lineshape than was previously used in theoretical predictions. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.
Current Scientific Issues in Large Scale Atmospheric Dynamics

NASA Technical Reports Server (NTRS)

Miller, T. L. (Compiler)

1986-01-01

Topics in large scale atmospheric dynamics are discussed. Aspects of atmospheric blocking, the influence of transient baroclinic eddies on planetary-scale waves, cyclogenesis, the effects of orography on planetary scale flow, small scale frontal structure, and simulations of gravity waves in frontal zones are discussed.
Europlanet Research Infrastructure: Planetary Simulation Facilities

NASA Astrophysics Data System (ADS)

Davies, G. R.; Mason, N. J.; Green, S.; Gómez, F.; Prieto, O.; Helbert, J.; Colangeli, L.; Srama, R.; Grande, M.; Merrison, J.

2008-09-01

EuroPlanet The Europlanet Research Infrastructure consortium funded under FP7 aims to provide the EU Planetary Science community greater access for to research infrastructure. A series of networking and outreach initiatives will be complimented by joint research activities and the formation of three Trans National Access distributed service laboratories (TNA's) to provide a unique and comprehensive set of analogue field sites, laboratory simulation facilities, and extraterrestrial sample analysis tools. Here we report on the infrastructure that comprises the second TNA; Planetary Simulation Facilities. 11 laboratory based facilities are able to recreate the conditions found in the atmospheres and on the surfaces of planetary systems with specific emphasis on Martian, Titan and Europa analogues. The strategy has been to offer some overlap in capabilities to ensure access to the highest number of users and to allow for progressive and efficient development strategies. For example initial testing of mobility capability prior to the step wise development within planetary atmospheres that can be made progressively more hostile through the introduction of extreme temperatures, radiation, wind and dust. Europlanet Research Infrastructure Facilties: Mars atmosphere simulation chambers at VUA and OU These relatively large chambers (up to 1 x 0.5 x 0.5 m) simulate Martian atmospheric conditions and the dual cooling options at VUA allows stabilised instrument temperatures while the remainder of the sample chamber can be varied between 220K and 350K. Researchers can therefore assess analytical protocols for instruments operating on Mars; e.g. effect of pCO2, temperature and material (e.g., ± ice) on spectroscopic and laser ablation techniques while monitoring the performance of detection technologies such as CCD at low T & variable p H2O & pCO2. Titan atmosphere and surface simulation chamber at OU The chamber simulates Titan's atmospheric composition under a range of pressures and temperatures and through provision of external UV light and or electrical discharge can be used to form the well known Titan Aerosol species, which can subsequently be analysed using one of several analytical techniques (UV-Vis, FTIR and mass spectrometry). Simulated surfaces can be produced (icy surfaces down to 15K) and subjected to a variety of light and particles (electron and ion) sources. Chemical and physical changes in the surface may be explored using remote spectroscopy. Planetary Simulation chamber for low density atmospheres INTA-CAB The planetary simulation chamber-ultra-high vacuum equipment (PSC-UHV) has been designed to study planetary surfaces and low dense atmospheres, space environments or any other hypothetic environment at UHV. Total pressure ranges from 7 mbar (Martian conditions) to 5x10-9 mbar. A residual gas analyzer regulates gas compositions to ppm precision. Temperature ranges from 4K to 325K and most operations are computer controlled. Radiation levels are simulated using a deuterium UV lamp, and ionization sources. 5 KV electron and noble-gas discharge UV allows measurement of IR and UV spectra and chemical compositions are determined by mass spectroscopy. Planetary Simulation chamber for high density planetary atmospheres at INTA-CAB The facility allows experimental study of planetary environments under high pressure, and was designed to include underground, seafloor and dense atmosphere environments. Analytical capabilities include Raman spectra, physicochemical properties of materials, e.a. thermal conductivity. P-T can be controlled as independent variables to allow monitoring of the tolerance of microorganisms and the stability of materials and their phase changes. Planetary Simulation chamber for icy surfaces at INTA-CAB This chamber is being developed to the growth of ice samples to simulate the chemical and physical properties of ices found on both planetary bodies and their moons. The goal is to allow measurement of the physical properties of ice samples formed under planetary conditions to assess how rheology varies with pressure and temperature and grain size to gain a far better understanding of how tectonics may operate on icy moons. Hot planetary surfaces simulation chamber at DLR The planetary simulation chamber is to study the behaviour of planetary analogue materials on the surface of hot (airless) bodies in the solar system. Samples can be heated up to temperatures of 500°C simulating conditions found on the surface of Mercury and Venus. This enables highly accurate thermal emission measurements using the integrated infrared spectrometer and calibrated sources. Thermal gradients can be applied to samples to simulate diurnal thermal cycles and examine thermal stresses in materials. The chamber can be placed under vacuum or purged with gas. In addition, to the high temperature chamber a number of further planetary simulation chambers are available equipped with LIBS and Raman-spectroscopy equipment. Dust analogue simulation chamber at INAF/OACN This facility produces and characterises dust analogues (arc discharge, laser ablation, grinding of minerals, ices) in a variety of simulation chambers under variable pressure (10-6 - 10-3 mbar), temperature (80 - 330 K) and gas composition. Dust and analogues are characterised by a variety of Spectroscopic (absorption, transmission, diffuse-specular reflectance) and imaging techniques (SEM) and can be subjected to thermal annealing, ion bombardment and UV irradiation. Dust accelerator facility at Max Planck Institüt Nuclear Physics, Heidelberg. This facility allows the investigation of hypervelocity dust impacts onto various materials. Dust grain materials from nano to micron sizes are accelerated using a 2 MV Vande- Graaff to velocities between 1 and 60 km/s comparable to the planetary rings of the giant gas planets and impact ejecta processes on the surface of small bodies (asteroids, comets) as well as moons and planetary surfaces. Potential phenomena for study include dust charging, dust magentosphere interactions, dust impact flashes and the possibility of obtaining compositional measurements of impact plasma plumes. Mars surface simulation Laboratory, Aberystwyth University. A Planetary Analogue Terrain Laboratory facilitates comprehensive mission operations emulation experiments designed to interpret and maximise scientific data return from robotic instruments. This facility includes Mars Soil Simulant and `science target' rocks that have been fully characterised. The terrain also has an area for sub-surface sampling. An Access Grid Node allows simulation of remote control operation and diminishes the need for direct onsite attendance. PAT Lab has a large selection of software tools for rover, robot arm and instrument modelling and simulation, and for the processing and visualisation of captured instrument data. Instrument motion is measured using a Vicon motion capture system with a resolution < 0.1 mm. Dusty wind tunnel at Aarhus University, Denmark The Aarhus wind tunnel simulates wind driven dust exposure on Mars. This allows study into analogue materials, dust/surface processes, meteorological condition and microbiological survival under Martian conditions. The multipurpose facility is used to quantify dust deposition (i.e. on optical surfaces, electrical or mechanical components) and examine the operation of instrumentation in dusty/windy environment under Martian conditions (pressure, gas composition & temperature). This includes calibration of wind flow instrumentation and dust sensors.
Laboratory Evaluation and Application of Microwave Absorption Properties Under Simulated Conditions for Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1998-01-01

Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties taken under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, laboratory measurements completed recently by Kolodner and Steffes (ICARUS 132, pp. 151-169, March 1998, attached as Appendix A) under this grant (NAGS-4190), have shown that the opacity from gaseous H2SO4 under simulated Venus conditions is best described by a different formalism than was previously used. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both spacecraft entry probe and orbiter radio occultation experiments and by radio astronomical observations, and over a range of frequencies which correspond to those used in such experiments, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.
Time-dependent simulations of disk-embedded planetary atmospheres

NASA Astrophysics Data System (ADS)

Stökl, A.; Dorfi, E. A.

2014-03-01

At the early stages of evolution of planetary systems, young Earth-like planets still embedded in the protoplanetary disk accumulate disk gas gravitationally into planetary atmospheres. The established way to study such atmospheres are hydrostatic models, even though in many cases the assumption of stationarity is unlikely to be fulfilled. Furthermore, such models rely on the specification of a planetary luminosity, attributed to a continuous, highly uncertain accretion of planetesimals onto the surface of the solid core. We present for the first time time-dependent, dynamic simulations of the accretion of nebula gas into an atmosphere around a proto-planet and the evolution of such embedded atmospheres while integrating the thermal energy budget of the solid core. The spherical symmetric models computed with the TAPIR-Code (short for The adaptive, implicit RHD-Code) range from the surface of the rocky core up to the Hill radius where the surrounding protoplanetary disk provides the boundary conditions. The TAPIR-Code includes the hydrodynamics equations, gray radiative transport and convective energy transport. The results indicate that diskembedded planetary atmospheres evolve along comparatively simple outlines and in particular settle, dependent on the mass of the solid core, at characteristic surface temperatures and planetary luminosities, quite independent on numerical parameters and initial conditions. For sufficiently massive cores, this evolution ultimately also leads to runaway accretion and the formation of a gas planet.
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1989-01-01

Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. Work performed has shown that laboratory measurements of the millimeter-wave opacity of ammonia between 7.5 mm and 9.3 mm and also at the 3.2 mm wavelength require a different lineshape to be used in the theoretical prediction for millimeter-wave ammonia opacity than was previously used. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.
Study of Some Planetary Atmospheres Features by Probe Entry and Descent Simulations

NASA Technical Reports Server (NTRS)

Gil, P. J. S.; Rosa, P. M. B.

2005-01-01

Characterization of planetary atmospheres is analyzed by its effects in the entry and descent trajectories of probes. Emphasis is on the most important variables that characterize atmospheres e.g. density profile with altitude. Probe trajectories are numerically determined with ENTRAP, a developing multi-purpose computational tool for entry and descent trajectory simulations capable of taking into account many features and perturbations. Real data from Mars Pathfinder mission is used. The goal is to be able to determine more accurately the atmosphere structure by observing real trajectories and what changes are to expect in probe descent trajectories if atmospheres have different properties than the ones assumed initially.
Laboratory Evaluation and Application of Microwave Absorption Properties under Simulated Conditions for Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

2002-01-01

Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth-based or spacecraft-based radio astronomical (emission) observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or the use of laboratory measurements of such properties taken under environmental conditions that are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurements have shown that the centimeter-wavelength opacity from gaseous phosphine (PH3) under simulated conditions for the outer planets far exceeds that predicted from theory over a wide range of temperatures and pressures. This fundamentally changed the resulting interpretation of Voyager radio occultation data at Saturn and Neptune. It also directly impacts planning and scientific goals for study of Saturn's atmosphere with the Cassini Radio Science Experiment and the Rossini RADAR instrument. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both spacecraft entry probe and orbiter (or flyby) radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft- and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres,
DYNAMICAL ACCRETION OF PRIMORDIAL ATMOSPHERES AROUND PLANETS WITH MASSES BETWEEN 0.1 AND 5 M {sub ⊕} IN THE HABITABLE ZONE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stökl, Alexander; Dorfi, Ernst A.; Johnstone, Colin P.

2016-07-10

In the early, disk-embedded phase of evolution of terrestrial planets, a protoplanetary core can accumulate gas from the circumstellar disk into a planetary envelope. In order to relate the accumulation and structure of this primordial atmosphere to the thermal evolution of the planetary core, we calculated atmosphere models characterized by the surface temperature of the core. We considered cores with masses between 0.1 and 5 M {sub ⊕} situated in the habitable zone around a solar-like star. The time-dependent simulations in 1D-spherical symmetry include the hydrodynamics equations, gray radiative transport, and convective energy transport. Using an implicit time integration scheme,more » we can use large time steps and and thus efficiently cover evolutionary timescales. Our results show that planetary atmospheres, when considered with reference to a fixed core temperature, are not necessarily stable, and multiple solutions may exist for one core temperature. As the structure and properties of nebula-embedded planetary atmospheres are an inherently time-dependent problem, we calculated estimates for the amount of primordial atmosphere by simulating the accretion process of disk gas onto planetary cores and the subsequent evolution of the embedded atmospheres. The temperature of the planetary core is thereby determined from the computation of the internal energy budget of the core. For cores more massive than about one Earth mass, we obtain that a comparatively short duration of the disk-embedded phase (∼10{sup 5} years) is sufficient for the accumulation of significant amounts of hydrogen atmosphere that are unlikely to be removed by later atmospheric escape processes.« less
A Study on Planetary Atmospheric Circulations using THOR

NASA Astrophysics Data System (ADS)

Mendonça, João; Grosheintz, Luc; Lukas Grimm, Simon; Heng, Kevin

2015-12-01

The large variety of planetary parameters observed leads us to think that exoplanets may show a large range of possible climates. It is therefore of the uttermost importance to investigate the influence of astronomical and planetary bulk parameters in driving the atmospheric circulations. In the solar system the results from planetary spacecraft missions have demonstrated how different the planetary climate and atmospheric circulations can be. The study of exoplanets will require probing a far wider range of physical and orbital parameters than the ones of our neighbor planets. For this reason, such a study will involve exploring an even larger diversity of circulation and climate regimes. Our new atmospheric model, THOR, is intended to be extremely flexible and to explore the large diversity of planetary atmospheres.THOR is part of the Exoclimes Simulation Platform, and is a project of the Exoplanet and Exoclimes Group (see www.exoclime.org). THOR solves the complex atmospheric fluid equations in a rotating sphere (fully compressible - nonhydrostatic system) using an icosahedral grid. The main advantages of using our new platform against other recent exoplanet models is that 1) The atmospheric fluid equations are completely represented and no approximations are used that could compromise the physics of the problem; 2) The model uses for the first time in exoplanet studies, a specific icosahedral grid that solves the pole problem; 3) The interface is user friendly and can be easily adapted to a multitude of atmospheric conditions; 4) By using GPU computation, our code greatly improves the typical code running time.We will present and discuss the first detailed results of our simulations, more specifically of two benchmark tests that are a representative sample of the large range of exoplanetary parameters: Earth-like conditions (the Held-Suarez test) and a tidally locked hot-Jupiter. THOR has successfully passed these tests and is able to determine the main mechanisms driving the circulation in the simulated planets. From the 3D numerical simulations we found that some hot-Jupiters atmospheres can sustain multiple dynamical steady states. The results also suggest the presence of a new mechanism that transports heat from the upper to the lower atmosphere. The presence and impact of this mechanism in the global temperature will be discussed in this presentation.
PELS (Planetary Environmental Liquid Simulator): a new type of simulation facility to study extraterrestrial aqueous environments.

PubMed

Martin, Derek; Cockell, Charles S

2015-02-01

Investigations of other planetary bodies, including Mars and icy moons such as Enceladus and Europa, show that they may have hosted aqueous environments in the past and may do so even today. Therefore, a major challenge in astrobiology is to build facilities that will allow us to study the geochemistry and habitability of these extraterrestrial environments. Here, we describe a simulation facility (PELS: Planetary Environmental Liquid Simulator) with the capability for liquid input and output that allows for the study of such environments. The facility, containing six separate sample vessels, allows for statistical replication of samples. Control of pressure, gas composition, UV irradiation conditions, and temperature allows for the precise replication of aqueous conditions, including subzero brines under martian atmospheric conditions. A sample acquisition system allows for the collection of both liquid and solid samples from within the chamber without breaking the atmospheric conditions, enabling detailed studies of the geochemical evolution and habitability of past and present extraterrestrial environments. The facility we describe represents a new frontier in planetary simulation-continuous flow-through simulation of extraterrestrial aqueous environments.
Two Regimes of Interaction of a Hot Jupiter’s Escaping Atmosphere with the Stellar Wind and Generation of Energized Atomic Hydrogen Corona

NASA Astrophysics Data System (ADS)

Shaikhislamov, I. F.; Khodachenko, M. L.; Lammer, H.; Kislyakova, K. G.; Fossati, L.; Johnstone, C. P.; Prokopov, P. A.; Berezutsky, A. G.; Zakharov, Yu. P.; Posukh, V. G.

2016-12-01

The interaction of escaping the upper atmosphere of a hydrogen-rich non-magnetized analog of HD 209458b with a stellar wind (SW) of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic (HD) model. A realistic Sun-like spectrum of X-ray and ultraviolet radiation, which ionizes and heats the planetary atmosphere, together with hydrogen photochemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric HD outflow. Two different regimes of the planetary and SW interaction have been modeled. These are: (1) the “captured by the star” regime, when the tidal force and pressure gradient drive the planetary material beyond the Roche lobe toward the star, and (2) the “blown by the wind” regime, when sufficiently strong SW confines the escaping planetary atmosphere and channels it into the tail. The model simulates in detail the HD interaction between the planetary atoms, protons and the SW, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud, either as a paraboloid shell between the ionopause and bowshock (for the “blown by the wind” regime), or a turbulent layer at the contact boundary between the planetary stream and SW (for the “captured by the star” regime) are of importance for the interpretation of Lyα absorption features in exoplanetary transit spectra and characterization of the plasma environments.
Assessing the Habitability of TRAPPIST-1e: MHD Simulations of Atmospheric Loss Due to CMEs and Stellar Wind

NASA Astrophysics Data System (ADS)

Harbach, Laura Marshall; Drake, Jeremy J.; Garraffo, Cecilia; Alvarado-Gomez, Julian D.; Moschou, Sofia P.; Cohen, Ofer

2018-01-01

Recently, three rocky planets were discovered in the habitable zone of the nearby planetary system TRAPPIST-1. The increasing number of exoplanet detections has led to further research into the planetary requirements for sustaining life. Habitable zone occupants have, in principle, the capacity to retain liquid water, whereas actual habitability might depend on atmospheric retention. However, stellar winds and photon radiation interactions with the planet can lead to severe atmospheric depletion and have a catastrophic impact on a planet’s habitability. While the implications of photoevaporation on atmospheric erosion have been researched to some degree, the influence of stellar winds and Coronal Mass Ejections (CMEs) has yet to be analyzed in detail. Here, we model the effect of the stellar wind and CMEs on the atmospheric envelope of a planet situated in the orbit of TRAPPIST-1e using 3D magnetohydrodynamic (MHD) simulations. In particular, we discuss the atmospheric loss due to the effect of a CME, and the relevance of the stellar and planetary magnetic fields on the sustainability of M-dwarf exoplanetary atmospheres.
Planetary Atmosphere and Surfaces Chamber (PASC): A Platform to Address Various Challenges in Astrobiology

NASA Astrophysics Data System (ADS)

Mateo-Marti, Eva

2014-08-01

The study of planetary environments of astrobiological interest has become a major challenge. Because of the obvious technical and economical limitations on in situ planetary exploration, laboratory simulations are one of the most feasible research options to make advances both in planetary science and in developing a consistent description of the origin of life. With this objective in mind, we applied vacuum technology to the design of versatile vacuum chambers devoted to the simulation of planetary atmospheres' conditions. These vacuum chambers are able to simulate atmospheres and surface temperatures representative of the majority of planetary objects, and they are especially appropriate for studying the physical, chemical and biological changes induced in a particular sample by in situ irradiation or physical parameters in a controlled environment. Vacuum chambers are a promising potential tool in several scientific and technological fields, such as engineering, chemistry, geology and biology. They also offer the possibility of discriminating between the effects of individual physical parameters and selected combinations thereof. The implementation of our vacuum chambers in combination with analytical techniques was specifically developed to make feasible the in situ physico-chemical characterization of samples. Many wide-ranging applications in astrobiology are detailed herein to provide an understanding of the potential and flexibility of these experimental systems. Instruments and engineering technology for space applications could take advantage of our environment-simulation chambers for sensor calibration. Our systems also provide the opportunity to gain a greater understanding of the chemical reactivity of molecules on surfaces under different environments, thereby leading to a greater understanding of interface processes in prebiotic chemical reactions and facilitating studies of UV photostability and photochemistry on surfaces. Furthermore, the stability and presence of certain minerals on planetary surfaces and the potential habitability of microorganisms under various planetary environmental conditions can be studied using our apparatus. Therefore, these simulation chambers can address multiple different challenging and multidisciplinary astrobiological studies.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaikhislamov, I. F.; Prokopov, P. A.; Berezutsky, A. G.

The interaction of escaping the upper atmosphere of a hydrogen-rich non-magnetized analog of HD 209458b with a stellar wind (SW) of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic (HD) model. A realistic Sun-like spectrum of X-ray and ultraviolet radiation, which ionizes and heats the planetary atmosphere, together with hydrogen photochemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric HD outflow. Two different regimes of the planetary and SW interaction have been modeled. These are: (1) the “ captured by the star ” regime, whenmore » the tidal force and pressure gradient drive the planetary material beyond the Roche lobe toward the star, and (2) the “ blown by the wind ” regime, when sufficiently strong SW confines the escaping planetary atmosphere and channels it into the tail. The model simulates in detail the HD interaction between the planetary atoms, protons and the SW, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud, either as a paraboloid shell between the ionopause and bowshock (for the “ blown by the wind ” regime), or a turbulent layer at the contact boundary between the planetary stream and SW (for the “ captured by the star ” regime) are of importance for the interpretation of Ly α absorption features in exoplanetary transit spectra and characterization of the plasma environments.« less
Whole Atmosphere Modeling and Data Analysis: Success Stories, Challenges and Perspectives

NASA Astrophysics Data System (ADS)

Yudin, V. A.; Akmaev, R. A.; Goncharenko, L. P.; Fuller-Rowell, T. J.; Matsuo, T.; Ortland, D. A.; Maute, A. I.; Solomon, S. C.; Smith, A. K.; Liu, H.; Wu, Q.

2015-12-01

At the end of the 20-th century Raymond Roble suggested an ambitious target of developing an atmospheric general circulation model (GCM) that spans from the surface to the thermosphere for modeling the coupled atmosphere-ionosphere with drivers from terrestrial meteorology and solar-geomagnetic inputs. He pointed out several areas of research and applications that would benefit highly from the development and improvement of whole atmosphere modeling. At present several research groups using middle and whole atmosphere models have attempted to perform coupled ionosphere-thermosphere predictions to interpret the "unexpected" anomalies in the electron content, ions and plasma drifts observed during recent stratospheric warming events. The recent whole atmosphere inter-comparison case studies also displayed striking differences in simulations of prevailing flows, planetary waves and dominant tidal modes even when the lower atmosphere domain of those models were constrained by similar meteorological analyses. We will present the possible reasons of such differences between data-constrained whole atmosphere simulations when analyses with 6-hour time resolution are used and discuss the potential model-data and model-model differences above the stratopause. The possible shortcomings of the whole atmosphere simulations associated with model physics, dynamical cores and resolutions will be discussed. With the increased confidence in the space-borne temperature, winds and ozone observations and extensive collections of ground-based upper atmosphere observational facilities, the whole atmosphere modelers will be able to quantify annual and year-to-variability of the zonal mean flows, planetary wave and tides. We will demonstrate the value of tidal and planetary wave variability deduced from the space-borne data and ground-based systems for evaluation and tune-up of whole atmosphere simulations including corrections of systematic model errors. Several success stories on the middle and whole atmosphere simulations coupled with the ionosphere models will be highlighted, and future perspectives for links of the space and terrestrial weather predictions constrained by current and scheduled ionosphere-thermosphere-mesosphere satellite missions will be presented

The spectroscopic search for the trace aerosols in the planetary atmospheres - the results of numerical simulations

NASA Astrophysics Data System (ADS)

Blecka, Maria I.

2010-05-01

The passive remote spectrometric methods are important in examinations the atmospheres of planets. The radiance spectra inform us about values of thermodynamical parameters and composition of the atmospheres and surfaces. The spectral technology can be useful in detection of the trace aerosols like biological substances (if present) in the environments of the planets. We discuss here some of the aspects related to the spectroscopic search for the aerosols and dust in planetary atmospheres. Possibility of detection and identifications of biological aerosols with a passive InfraRed spectrometer in an open-air environment is discussed. We present numerically simulated, based on radiative transfer theory, spectroscopic observations of the Earth atmosphere. Laboratory measurements of transmittance of various kinds of aerosols, pollens and bacterias were used in modeling.
Organic chemistry in Titan's atmosphere

NASA Technical Reports Server (NTRS)

Scattergood, T.

1982-01-01

Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.
Endogeneous sources: atmospheric organic syntheses, tholins and ground trust

NASA Astrophysics Data System (ADS)

Raulin, F.; Bernard, J.; Coll, P.; Nna Mvondo, D.; Ramirez, S.; Navarro-Gonzalez, R.

From the many simulation experiments which have been carried out for the last 50 years on gas phase organic synthesis but also from several theoretical modeling works, it is clear today that in situ production of organic molecules in planetary atmosphere is efficient only if the starting atmosphere is chemically reduced. In that case many simple organics can be produced like formaldehyde, (HCHO), hydrogen cyanide (HCN), cyanoacetylene (HC3N) and other nitriles, but also more complex refractory organics - usually named "tholins" - are obtained. Those tholins are still of very poorly known composition, but are of great exobiological interest since they are the precursors of many compounds of biological interest, in particular amino acids, purines and pyrimidines bases. How realistic are those experimental as well as theoretical simulations? The many planetary data which have been obtained until now on the so diversified planetary atmospheres of the solar system provide a fantastic opportunity to answer such question and validate the laboratory data with "ground trust". Indeed, at the exception of the Earth atmosphere (in which Life is the essential source of organics), any organic compound has been detected in the inner planets. On the contrary, all the outer planets, from Jupiter to Neptune (and even Pluto) involve organic chemical processes, through the chemistry of their atmosphere, and methane photochemistry. They are also present in the dense atmosphere of Titan, the largest satellite of Saturn, (in the gas and aerosol phases), in the much thinner atmosphere of Triton, the largest satellite of Neptune (mainly in the solid phase, on its surface), and on the surface of many of the other satellites of the outer planets. Thus, although we have so far no real direct evidence for this assumption, laboratory data strongly suggest that extraterrestrial organic chemistry systematically involves tholins-like matter. The different aspects of extraterrestrial atmospheric organic chemistry will be presented and discussed, on the basis of recent laboratory data, in particular from simulation experiments related to oxidized and reduced atmospheres and planetary observations.
Time-Dependent Simulations of the Formation and Evolution of Disk-Accreted Atmospheres Around Terrestrial Planets

NASA Astrophysics Data System (ADS)

Stoekl, Alexander; Dorfi, Ernst

2014-05-01

In the early, embedded phase of evolution of terrestrial planets, the planetary core accumulates gas from the circumstellar disk into a planetary envelope. This atmosphere is very significant for the further thermal evolution of the planet by forming an insulation around the rocky core. The disk-captured envelope is also the staring point for the atmospheric evolution where the atmosphere is modified by outgassing from the planetary core and atmospheric mass loss once the planet is exposed to the radiation field of the host star. The final amount of persistent atmosphere around the evolved planet very much characterizes the planet and is a key criterion for habitability. The established way to study disk accumulated atmospheres are hydrostatic models, even though in many cases the assumption of stationarity is unlikely to be fulfilled. We present, for the first time, time-dependent radiation hydrodynamics simulations of the accumulation process and the interaction between the disk-nebula gas and the planetary core. The calculations were performed with the TAPIR-Code (short for The adaptive, implicit RHD-Code) in spherical symmetry solving the equations of hydrodynamics, gray radiative transport, and convective energy transport. The models range from the surface of the solid core up to the Hill radius where the planetary envelope merges into the surrounding protoplanetary disk. Our results show that the time-scale of gas capturing and atmospheric growth strongly depends on the mass of the solid core. The amount of atmosphere accumulated during the lifetime of the protoplanetary disk (typically a few Myr) varies accordingly with the mass of the planet. Thus, a core with Mars-mass will end up with about 10 bar of atmosphere while for an Earth-mass core, the surface pressure reaches several 1000 bar. Even larger planets with several Earth masses quickly capture massive envelopes which in turn become gravitationally unstable leading to runaway accretion and the eventual formation of a gas planet.
Simulation of Prebiotic Processing by Comet and Meteoroid Impact: Implications for Life on Early Earth and Other Planets

NASA Technical Reports Server (NTRS)

Dateo, Christopher E.

2003-01-01

We develop a reacting flow model to simulate the shock induced chemistry of comets and meteoroids entering planetary atmospheres. Various atmospheric compositions comprising of simpler molecules (i.e., CH4, CO2, H2O, etc.) are investigated to determine the production efficiency of more complex prebiotic molecules as a function of composition, pressure, and entry velocity. The possible role of comets and meteoroids in creating the inventory of prebiotic material necessary for life on Early Earth is considered. Comets and meteoroids can also introduce new materials from the Interstellar Medium (ISM) to planetary atmospheres. The ablation of water from comets, introducing the element oxygen into Titan's atmosphere will also be considered and its implications for the formation of organic and prebiotic material.
Simulating super earth atmospheres in the laboratory

NASA Astrophysics Data System (ADS)

Claudi, R.; Erculiani, M. S.; Galletta, G.; Billi, D.; Pace, E.; Schierano, D.; Giro, E.; D'Alessandro, M.

2016-01-01

Several space missions, such as JWST, TESS and the very recently proposed ARIEL, or ground-based experiments, as SPHERE and GPI, have been proposed to measure the atmospheric transmission, reflection and emission spectra of extrasolar planets. The planet atmosphere characteristics and possible biosignatures will be inferred by studying planetary spectra in order to identify the emission/absorption lines/bands from atmospheric molecules such as water (H2O), carbon monoxide (CO), methane (CH4), ammonia (NH3), etc. In particular, it is important to know in detail the optical characteristics of gases in the typical physical conditions of the planetary atmospheres and how these characteristics could be affected by radiation driven photochemical and biochemical reaction. The main aim of the project `Atmosphere in a Test Tube' is to provide insights on exoplanet atmosphere modification due to biological intervention. This can be achieved simulating planetary atmosphere at different pressure and temperature conditions under the effects of radiation sources, used as proxies of different bands of the stellar emission. We are tackling the characterization of extrasolar planet atmospheres by mean of innovative laboratory experiments described in this paper. The experiments are intended to reproduce the conditions on warm earths and super earths hosted by low-mass M dwarfs primaries with the aim to understand if a cyanobacteria population hosted on a Earth-like planet orbiting an M0 star is able to maintain its photosynthetic activity and produce traceable signatures.
Simulating the escaping atmospheres of hot gas planets in the solar neighborhood

NASA Astrophysics Data System (ADS)

Salz, M.; Czesla, S.; Schneider, P. C.; Schmitt, J. H. M. M.

2016-02-01

Absorption of high-energy radiation in planetary thermospheres is generally believed to lead to the formation of planetary winds. The resulting mass-loss rates can affect the evolution, particularly of small gas planets. We present 1D, spherically symmetric hydrodynamic simulations of the escaping atmospheres of 18 hot gas planets in the solar neighborhood. Our sample only includes strongly irradiated planets, whose expanded atmospheres may be detectable via transit spectroscopy using current instrumentation. The simulations were performed with the PLUTO-CLOUDY interface, which couples a detailed photoionization and plasma simulation code with a general MHD code. We study the thermospheric escape and derive improved estimates for the planetary mass-loss rates. Our simulations reproduce the temperature-pressure profile measured via sodium D absorption in HD 189733 b, but show still unexplained differences in the case of HD 209458 b. In contrast to general assumptions, we find that the gravitationally more tightly bound thermospheres of massive and compact planets, such as HAT-P-2 b are hydrodynamically stable. Compact planets dispose of the radiative energy input through hydrogen Lyα and free-free emission. Radiative cooling is also important in HD 189733 b, but it decreases toward smaller planets like GJ 436 b. Computing the planetary Lyα absorption and emission signals from the simulations, we find that the strong and cool winds of smaller planets mainly cause strong Lyα absorption but little emission. Compact and massive planets with hot, stable thermospheres cause small absorption signals but are strong Lyα emitters, possibly detectable with the current instrumentation. The absorption and emission signals provide a possible distinction between these two classes of thermospheres in hot gas planets. According to our results, WASP-80 and GJ 3470 are currently the most promising targets for observational follow-up aimed at detecting atmospheric Lyα absorption signals. Simulated atmospheres are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A75
Effects of the planetary-scale waves on the temporal variations of the O2-1.27μm nightglow in the Venusian upper atmosphere

NASA Astrophysics Data System (ADS)

Hoshino, N.; Fujiwara, H.; Takagi, M.; Kasaba, Y.; Takahashi, Y.

2009-12-01

The O2-1.27 μm nightglow distribution, which has the peak intensity in the depression region of the day-to-night flow, gives us information of the wind field at about 95 km in Venus. The past nightglow observations [Crisp et al., 1996] showed that the intensity of the nightglow in the brightness region changed by 20 % in about one hour, and the brightness region disappeared in less than one day. The observation results obtained by Venus Express (VEX) also showed the temporal variations of the nightglow emission. Some simulation studies suggested contributions of gravity waves generated in the cloud deck (50-70 km) to the temporal variations. However, the causes of the temporal variations are still unknown. In recent years, the importance of planetary-scale waves for the dynamics of the Venusian atmosphere has been recognized. For example, Takagi and Matsuda [2006] suggested that the atmospheric superrotation was driven by the momentum transport due to the vertical propagation of the thermal tides generated in the Venus cloud deck. In order to estimate effects of the planetary-scale waves on the temporal variations of the nightglow, we have performed numerical simulations with a general circulation model (GCM), which includes the altitude region of 80 - about 200 km. The planetary-scale waves (thermal tides, Kelvin wave and Rosbby wave) are imposed at the lower boundary. The amplitudes and phase velocities of the waves are assumed from the study by Del Genio and Rossow [1990]. The nightglow intensity and its global distribution are calculated from the GCM results assuming the chemical equilibration. In this study, we investigate contributions of the planetary-scale waves on the temporal variations of the nightglow shown by past observations. In addition, we show the characteristics of the wave propagation and the interactions between the waves in the Venusian upper atmosphere. Venus Climate Orbiter (VCO), which will be launched in 2010 as the second Japanese planetary mission, is expected to provide precious information about the atmospheric waves at the cloud top (about 70 km) and the nightglow distributions in the thermosphere. We can understand effects of the atmospheric waves on the Venusian thermosphere quantitatively by performing simulations with new information about the atmospheric waves obtained from the detailed nightglow observations.
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1988-01-01

Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The key activity for this grant year has continued to be laboratory measurements of the microwave and millimeter-wave properties of the simulated atmospheres of the outer planets and their satellites. A Fabry-Perot spectrometer system capable of operation from 32 to 41 GHz was developed. Initially this spectrometer was used to complete laboratory measurements of the 7.5 to 9.3 mm absorption spectrum of ammonia. Laboratory measurements were begun at wavelengths near 3.2 mm, where a large number of observations of the emission from the outer planets were made. A description of this system is presented.
Extreme Environment Simulation - Current and New Capabilities to Simulate Venus and Other Planetary Bodies

NASA Technical Reports Server (NTRS)

Kremic, Tibor; Vento, Dan; Lalli, Nick; Palinski, Timothy

2014-01-01

Science, technology, and planetary mission communities have a growing interest in components and systems that are capable of working in extreme (high) temperature and pressure conditions. Terrestrial applications range from scientific research, aerospace, defense, automotive systems, energy storage and power distribution, deep mining and others. As the target environments get increasingly extreme, capabilities to develop and test the sensors and systems designed to operate in such environments will be required. An application of particular importance to the planetary science community is the ability for a robotic lander to survive on the Venus surface where pressures are nearly 100 times that of Earth and temperatures approach 500C. The scientific importance and relevance of Venus missions are stated in the current Planetary Decadal Survey. Further, several missions to Venus were proposed in the most recent Discovery call. Despite this interest, the ability to accurately simulate Venus conditions at a scale that can test and validate instruments and spacecraft systems and accurately simulate the Venus atmosphere has been lacking. This paper discusses and compares the capabilities that are known to exist within and outside the United States to simulate the extreme environmental conditions found in terrestrial or planetary surfaces including the Venus atmosphere and surface. The paper then focuses on discussing the recent additional capability found in the NASA Glenn Extreme Environment Rig (GEER). The GEER, located at the NASA Glenn Research Center in Cleveland, Ohio, is designed to simulate not only the temperature and pressure extremes described, but can also accurately reproduce the atmospheric compositions of bodies in the solar system including those with acidic and hazardous elements. GEER capabilities and characteristics are described along with operational considerations relevant to potential users. The paper presents initial operating results and concludes with a sampling of investigations or tests that have been requested or expected.
Large-Eddy Simulation. Guidelines for Its Application to Planetary Boundary Layer Research

DTIC Science & Technology

1984-08-01

34 engineering application of L98 was Deardorff’s simulation of turbulent channel flow, which was carried out at the National Center for Atmospheric...over the past 20 years, and yet in the perception of some observers * the applications of the resulting basic science to practical problem remain...COVERED -- Large Eddy Simulation: Guidelines for its .0 application to planetary boundary layer research Final Report Oct 83-Aug 84 S. PERFORMING ORG
ARTS, the Atmospheric Radiative Transfer Simulator - version 2.2, the planetary toolbox edition

NASA Astrophysics Data System (ADS)

Buehler, Stefan A.; Mendrok, Jana; Eriksson, Patrick; Perrin, Agnès; Larsson, Richard; Lemke, Oliver

2018-04-01

This article describes the latest stable release (version 2.2) of the Atmospheric Radiative Transfer Simulator (ARTS), a public domain software for radiative transfer simulations in the thermal spectral range (microwave to infrared). The main feature of this release is a planetary toolbox that allows simulations for the planets Venus, Mars, and Jupiter, in addition to Earth. This required considerable model adaptations, most notably in the area of gaseous absorption calculations. Other new features are also described, notably radio link budgets (including the effect of Faraday rotation that changes the polarization state) and the treatment of Zeeman splitting for oxygen spectral lines. The latter is relevant, for example, for the various operational microwave satellite temperature sensors of the Advanced Microwave Sounding Unit (AMSU) family.
Isca, v1.0: a framework for the global modelling of the atmospheres of Earth and other planets at varying levels of complexity

NASA Astrophysics Data System (ADS)

Vallis, Geoffrey K.; Colyer, Greg; Geen, Ruth; Gerber, Edwin; Jucker, Martin; Maher, Penelope; Paterson, Alexander; Pietschnig, Marianne; Penn, James; Thomson, Stephen I.

2018-03-01

Isca is a framework for the idealized modelling of the global circulation of planetary atmospheres at varying levels of complexity and realism. The framework is an outgrowth of models from the Geophysical Fluid Dynamics Laboratory in Princeton, USA, designed for Earth's atmosphere, but it may readily be extended into other planetary regimes. Various forcing and radiation options are available, from dry, time invariant, Newtonian thermal relaxation to moist dynamics with radiative transfer. Options are available in the dry thermal relaxation scheme to account for the effects of obliquity and eccentricity (and so seasonality), different atmospheric optical depths and a surface mixed layer. An idealized grey radiation scheme, a two-band scheme, and a multiband scheme are also available, all with simple moist effects and astronomically based solar forcing. At the complex end of the spectrum the framework provides a direct connection to comprehensive atmospheric general circulation models. For Earth modelling, options include an aquaplanet and configurable continental outlines and topography. Continents may be defined by changing albedo, heat capacity, and evaporative parameters and/or by using a simple bucket hydrology model. Oceanic Q fluxes may be added to reproduce specified sea surface temperatures, with arbitrary continental distributions. Planetary atmospheres may be configured by changing planetary size and mass, solar forcing, atmospheric mass, radiation, and other parameters. Examples are given of various Earth configurations as well as a giant planet simulation, a slowly rotating terrestrial planet simulation, and tidally locked and other orbitally resonant exoplanet simulations. The underlying model is written in Fortran and may largely be configured with Python scripts. Python scripts are also used to run the model on different architectures, to archive the output, and for diagnostics, graphics, and post-processing. All of these features are publicly available in a Git-based repository.
A method for coupling a parameterization of the planetary boundary layer with a hydrologic model

NASA Technical Reports Server (NTRS)

Lin, J. D.; Sun, Shu Fen

1986-01-01

Deardorff's parameterization of the planetary boundary layer is adapted to drive a hydrologic model. The method converts the atmospheric conditions measured at the anemometer height at one site to the mean values in the planetary boundary layer; it then uses the planetary boundary layer parameterization and the hydrologic variables to calculate the fluxes of momentum, heat and moisture at the atmosphere-land interface for a different site. A simplified hydrologic model is used for a simulation study of soil moisture and ground temperature on three different land surface covers. The results indicate that this method can be used to drive a spatially distributed hydrologic model by using observed data available at a meteorological station located on or nearby the site.
Dynamics and Chemistry in Jovian Atmospheres: 2D Hydrodynamical Simulations

NASA Astrophysics Data System (ADS)

Bordwell, B. R.; Brown, B. P.; Oishi, J.

2016-12-01

A key component of our understanding of the formation and evolution of planetary systems is chemical composition. Problematically, however, in the atmospheres of cooler gas giants, dynamics on the same timescale as chemical reactions pull molecular abundances out of thermochemical equilibrium. These disequilibrium abundances are treated using what is known as the "quench" approximation, based upon the mixing length theory of convection. The validity of this approximation is questionable, though, as the atmospheres of gas giants encompass two distinct dynamic regimes: convective and radiative. To resolve this issue, we conduct 2D hydrodynamical simulations using the state-of-the-art pseudospectral simulation framework Dedalus. In these simulations, we solve the fully compressible equations of fluid motion in a local slab geometry that mimics the structure of a planetary atmosphere (convective zone underlying a radiative zone). Through the inclusion of passive tracers, we explore the transport properties of both regimes, and assess the validity of the classical eddy diffusion parameterization. With the addition of active tracers, we examine the interactions between dynamical and chemical processes, and generate prescriptions for the observational community. By providing insight into mixing and feedback mechanisms in Jovian atmospheres, this research lays a solid foundation for future global simulations and the construction of physically-sound models for current and future observations.
Laboratory Simulations on Haze Formation in Cool Exoplanet Atmospheres

NASA Astrophysics Data System (ADS)

He, Chao; Horst, Sarah; Lewis, Nikole; Yu, Xinting; McGuiggan, Patricia; Moses, Julianne I.

2017-10-01

The Kepler mission has shown that the most abundant types of planets are super-Earths and mini-Neptunes among ~3500 confirmed exoplanets, and these types of exoplanets are expected to exhibit a wide variety of atmospheric compositions. Recent transit spectra have demonstrated that clouds and/or hazes could play a significant role in these planetary atmospheres (Deming et al. 2013, Knutson et al. 2014, Kreidberg et al. 2014, Pont, et al. 2013). However, very little laboratory work has been done to understand the formation of haze over a broad range of atmospheric compositions. Here we conducted a series of laboratory simulations to investigate haze formation in a range of planetary atmospheres using our newly built Planetary HAZE Research (PHAZER) chamber (He et al. 2017). We ran experimental simulations for nine different atmospheres: three temperatures (300 K, 400 K, and 600 K) and three metallicities (100, 1000, and 10000 times solar metallicity) using AC glow discharge as an energy source to irradiate gas mixtures. We found that haze particles are formed in all nine experiments, but the haze production rates are dramatically different for different cases. We investigated the particle sizes of the haze particles deposited on quartz discs using atomic force microscopy (AFM). The AFM images show that the particle size varies from 30 nm to 200 nm. The haze particles are more uniform for 100x solar metallicity experiments (30 nm to 40 nm) while the particles sizes for 1000x and 10000x solar metallicity experiments have wider distributions (30 nm to 200 nm). The particle size affects the scattering of light, and thus the temperature structure of planetary atmospheres. The haze production rates and particle size distributions obtained here can serve as critical inputs to atmospheric physical and chemical tools to understand the exoplanetary atmospheres and help guide future TESS and JWST observations of super-Earths and mini-Neptunes.Ref:Deming, D., et al. 2013, ApJ, 774, 95.He, C., et al. 2017, APJL, 841, L31.Knutson, H. A., et al. 2014, Nat. 505, 66.Kreidberg, L., et al. 2014, Nat. 505, 69.Pont, F., et al. 2013, MNRAS, 432, 2917.
Modelling of plasma processes in cometary and planetary atmospheres

NASA Astrophysics Data System (ADS)

Campbell, L.; Brunger, M. J.

2013-02-01

Electrons from the Sun, often accelerated by magnetospheric processes, produce low-density plasmas in the upper atmospheres of planets and their satellites. The secondary electrons can produce further ionization, dissociation and excitation, leading to enhancement of chemical reactions and light emission. Similar processes are driven by photoelectrons produced by sunlight in upper atmospheres during daytime. Sunlight and solar electrons drive the same processes in the atmospheres of comets. Thus for both understanding of planetary atmospheres and in predicting emissions for comparison with remote observations it is necessary to simulate the processes that produce upper atmosphere plasmas. In this review, we describe relevant models and their applications and address the importance of electron-impact excitation cross sections, towards gaining a quantitative understanding of the phenomena in question.
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, P. G.

1986-01-01

After long arduous work with the simulator, measurements of the refractivity and absorptivity of nitrogen under conditions similar to those for Titan were completed. The most significant measurements, however, were those of the microwave absorption from gaseous ammonia under simulated conditions for the Jovian atmospheres over wavelengths from 1.3 to 22 cm. The results of these measurements are critical in that they confirm the theoretical calculation of the ammonia opacity using the Ben-Reuven lineshape. The application of both these results, and results obtained previously, to planetary observations at microwave frequencies were especially rewarding. Applications of the results for ammonia to radio astronomical observations of Jupiter in the 1.3 to 20 cm wavelength range and the application of results for gaseous H2SO4 under simulated Venus conditions are discussed.
The LatHyS database for planetary plasma environment investigations: Overview and a case study of data/model comparisons

NASA Astrophysics Data System (ADS)

Modolo, R.; Hess, S.; Génot, V.; Leclercq, L.; Leblanc, F.; Chaufray, J.-Y.; Weill, P.; Gangloff, M.; Fedorov, A.; Budnik, E.; Bouchemit, M.; Steckiewicz, M.; André, N.; Beigbeder, L.; Popescu, D.; Toniutti, J.-P.; Al-Ubaidi, T.; Khodachenko, M.; Brain, D.; Curry, S.; Jakosky, B.; Holmström, M.

2018-01-01

We present the Latmos Hybrid Simulation (LatHyS) database, which is dedicated to the investigations of planetary plasma environment. Simulation results of several planetary objects (Mars, Mercury, Ganymede) are available in an online catalogue. The full description of the simulations and their results is compliant with a data model developped in the framework of the FP7 IMPEx project. The catalogue is interfaced with VO-visualization tools such AMDA, 3DView, TOPCAT, CLweb or the IMPEx portal. Web services ensure the possibilities of accessing and extracting simulated quantities/data. We illustrate the interoperability between the simulation database and VO-tools using a detailed science case that focuses on a three-dimensional representation of the solar wind interaction with the Martian upper atmosphere, combining MAVEN and Mars Express observations and simulation results.
The Hottest Hot Jupiters May Host Atmospheric Dynamos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogers, T. M.; McElwaine, J. N.

2017-06-01

Hot Jupiters have proven themselves to be a rich class of exoplanets that test our theories of planetary evolution and atmospheric dynamics under extreme conditions. Here, we present three-dimensional magnetohydrodynamic simulations and analytic results that demonstrate that a dynamo can be maintained in the thin, stably stratified atmosphere of a hot Jupiter, independent of the presumed deep-seated dynamo. This dynamo is maintained by conductivity variations arising from strong asymmetric heating from the planets’ host star. The presence of a dynamo significantly increases the surface magnetic field strength and alters the overall planetary magnetic field geometry, possibly affecting star–planet magnetic interactions.

A modeling study of the thermosphere-ionosphere interactions during the boreal winter and spring 2015-2016: Tidal and planetary-scale waves effect on the ionospheric structure.

NASA Astrophysics Data System (ADS)

Sassi, F.; McDonald, S. E.; McCormack, J. P.; Tate, J.; Liu, H.; Kuhl, D.

2017-12-01

The 2015-2016 boreal winter and spring is a dynamically very interesting time in the lower atmosphere: a minor high latitude stratospheric warming occurred in February 2016; an interrupted descent of the QBO was found in the tropical stratosphere; and a large warm ENSO took place in the tropical Pacific Ocean. The stratospheric warming, the QBO and ENSO are known to affect in different ways the meteorology of the upper atmosphere in different ways: low latitude solar tides and high latitude planetary-scale waves have potentially important implications on the structure of the ionosphere. In this study, we use global atmospheric analyses from a high-altitude version of the High-Altitude Navy Global Environmental Model (HA-NAVGEM) to constrain the meteorology of numerical simulations of the Specified Dynamics Whole Atmosphere Community Climate Model, extended version (SD-WACCM-X). We describe the large-scale behavior of tropical tides and mid-latitude planetary waves that emerge in the lower thermosphere. The effect on the ionosphere is captured by numerical simulations of the Navy Highly Integrated Thermosphere Ionosphere Demonstration System (Navy-HITIDES) that uses the meteorology generated by SD-WACCM-X to drive ionospheric simulations during this time period. We will analyze the impact of various dynamical fields on the zonal behavior of the ionosphere by selectively filtering the relevant dynamical modes.
Global Scale Atmospheric Processes Research Program Review

NASA Technical Reports Server (NTRS)

Worley, B. A. (Editor); Peslen, C. A. (Editor)

1984-01-01

Global modeling; satellite data assimilation and initialization; simulation of future observing systems; model and observed energetics; dynamics of planetary waves; First Global Atmospheric Research Program Global Experiment (FGGE) diagnosis studies; and National Research Council Research Associateship Program are discussed.
A Mechanism for Land-Atmosphere Feedback Involving Planetary Wave Structures

NASA Technical Reports Server (NTRS)

Koster, Randal D.; Chang, Yehui; Schubert, Siegfried D.

2014-01-01

While the ability of land surface conditions to influence the atmosphere has been demonstrated in various modeling and observational studies, the precise mechanisms by which land-atmosphere feedback occurs are still largely unknown particularly the mechanisms that allow land moisture state in one region to affect atmospheric conditions in another. Such remote impacts are examined here in the context of atmospheric general circulation model (AGCM) simulations, leading to the identification of one potential mechanism: the phase-locking and amplification of a planetary wave through the imposition of a spatial pattern of soil moisture at the land surface. This mechanism, shown here to be relevant in the AGCM, apparently also operates in nature, as suggested by supporting evidence found in reanalysis data.
A Numerical Study of Micrometeoroids Entering Titan's Atmosphere

NASA Technical Reports Server (NTRS)

Templeton, M.; Kress, M. E.

2011-01-01

A study using numerical integration techniques has been performed to analyze the temperature profiles of micrometeors entering the atmosphere of Saturn s moon Titan. Due to Titan's low gravity and dense atmosphere, arriving meteoroids experience a significant cushioning effect compared to those entering the Earth's atmosphere. Temperature profiles are presented as a function of time and altitude for a number of different meteoroid sizes and entry velocities, at an entry angle of 45. Titan's micrometeoroids require several minutes to reach peak heating (ranging from 200 to 1200 K), which occurs at an altitude of about 600 km. Gentle heating may allow for gradual evaporation of volatile components over a wide range of altitudes. Computer simulations have been performed using the Cassini/Huygens atmospheric data for Titan. Keywords micrometeoroid Titan atmosphere 1 Introduction On Earth, incoming micrometeoroids (100 m diameter) are slowed by collisions with air molecules in a relatively compact atmosphere, resulting in extremely rapid deceleration and a short heating pulse, often accompanied by brilliant meteor displays. On Titan, lower gravity leads to an atmospheric scale height that is much larger than on Earth. Thus, deceleration of meteors is less rapid and these particles undergo more gradual heating. This study uses techniques similar to those used for Earth meteoroid studies [1], exchanging Earth s planetary characteristics (e.g., mass and atmospheric profile) for those of Titan. Cassini/Huygens atmospheric data for Titan were obtained from the NASA Planetary Atmospheres Data Node [4]. The objectives of this study were 1) to model atmospheric heating of meteoroids for a range of micrometeor entry velocities for Titan, 2) to determine peak heating temperatures and rates for micrometeoroids entering Titan s atmosphere, and 3) to create a general simulation environment that can be extended to incorporate additional parameters and variables, including different atmospheric, meteoroid and planetary data. The micrometeoroid entry simulations made using Titan atmospheric data assume that, as on Earth, micrometeors are heated by collision with molecules in the atmosphere. Unlike on Earth where heating pulses last a few seconds and reach temperatures sufficient to melt silicates (> 1600 K [1]),
One-dimensional simulation of temperature and moisture in atmospheric and soil boundary layers

NASA Technical Reports Server (NTRS)

Bornstein, R. D.; Santhanam, K.

1981-01-01

Meteorologists are interested in modeling the vertical flow of heat and moisture through the soil in order to better simulate the vertical and temporal variations of the atmospheric boundary layer. The one dimensional planetary boundary layer model of is modified by the addition of transport equations to be solved by a finite difference technique to predict soil moisture.
Diurnal forcing of planetary atmospheres

NASA Technical Reports Server (NTRS)

Houben, Howard C.

1991-01-01

The utility of the Mars Planetary Boundary Layer Model (MPBL) for calculations in support of the Mars 94 balloon mission was substantially enhanced by the introduction of a balloon equation of motion into the model. Both vertical and horizontal excursions of the balloon are calculated along with its volume, temperature, and pressure. The simulations reproduce the expected 5-min vertical oscillations of a constant density balloon at altitude on Mars. The results of these calculations are presented for the nominal target location of the balloon. A nonlinear balanced model was developed for the Martian atmosphere. It was used to initialize a primitive equation model for the simulations of the Earth's atmosphere at the time of the El Chichon eruption in 1982. It is also used as an assimilation model to update the temperature and wind fields at frequent intervals.
Hydrodynamic escape from planetary atmospheres

NASA Astrophysics Data System (ADS)

Tian, Feng

Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Due to the existence of a singularity point near the transonic point, it is difficult to find transonic steady state solutions by solving the time-independent hydrodynamic equations. In addition to that, most previous works assume that all energy driving the escape flow is deposited in one narrow layer. This assumption not only results in less accurate solutions to the hydrodynamic escape problem, but also makes it difficult to include other chemical and physical processes in the hydrodynamic escape models. In this work, a numerical model describing the transonic hydrodynamic escape from planetary atmospheres is developed. A robust solution technique is used to solve the time dependent hydrodynamic equations. The method has been validated in an isothermal atmosphere where an analytical solution is available. The hydrodynamic model is applied to 3 cases: hydrogen escape from small orbit extrasolar planets, hydrogen escape from a hydrogen rich early Earth's atmosphere, and nitrogen/methane escape from Pluto's atmosphere. Results of simulations on extrasolar planets are in good agreement with the observations of the transiting extrasolar planet HD209458b. Hydrodynamic escape of hydrogen from other hypothetical close-in extrasolar planets are simulated and the influence of hydrogen escape on the long-term evolution of these extrasolar planets are discussed. Simulations on early Earth suggest that hydrodynamic escape of hydrogen from a hydrogen rich early Earth's atmosphere is about two orders magnitude slower than the diffusion limited escape rate. A hydrogen rich early Earth's atmosphere could have been maintained by the balance between the hydrogen escape and the supply of hydrogen into the atmosphere by volcanic outgassing. Origin of life may have occurred in the organic soup ocean created by the efficient formation of prebiotic molecules in the hydrogen rich early Earth's atmosphere. Simulations show that hydrodynamic escape of nitrogen from Pluto is able to remove a ~3 km layer of ice over the age of the solar system. The escape flux of neutral nitrogen may interact with the solar wind at Pluto's orbit and may be detected by the New Horizon mission.
Apparatus for experimental investigation of aerodynamic radiation with absorption by ablation products

NASA Technical Reports Server (NTRS)

Wells, W. L.; Snow, W. L.

1977-01-01

A description is given and calibration procedures are presented for an apparatus that is used to simulate aerodynamic radiant heating during planetary entry. The primary function of the apparatus is to simulate the spectral distribution of shock layer radiation and to determine absorption effects of simulated ablation products which are injected into the stagnation region flow field. An electric arc heater is used to heat gas mixtures that represent the planetary atmospheres of interest. Spectral measurements are made with a vacuum ultraviolet scanning monochromator.
Improved Mars Upper Atmosphere Climatology

NASA Technical Reports Server (NTRS)

Bougher, S. W.

2004-01-01

The detailed characterization of the Mars upper atmosphere is important for future Mars aerobraking activities. Solar cycle, seasonal, and dust trends (climate) as well as planetary wave activity (weather) are crucial to quantify in order to improve our ability to reasonably depict the state of the Mars upper atmosphere over time. To date, our best information is found in the Mars Global Surveyor (MGS) Accelerometer (ACC) database collected during Phase 1 (Ls = 184 - 300; F10.7 = 70 - 90) and Phase 2 (Ls = 30 - 90; F10.7 = 90 - 150) of aerobraking. This database (100 - 170 km) consists of thermospheric densities, temperatures, and scale heights, providing our best constraints for exercising the coupled Mars General Circulation Model (MGCM) and the Mars Thermospheric General Circulation Model (MTGCM). The Planetary Data System (PDS) contains level 0 and 2 MGS Accelerometer data, corresponding to atmospheric densities along the orbit track. Level 3 products (densities, temperatures, and scale heights at constant altitudes) are also available in the PDS. These datasets provide the primary model constraints for the new MGCM-MTGCM simulations summarized in this report. Our strategy for improving the characterization of the Mars upper atmospheres using these models has been three-fold : (a) to conduct data-model comparisons using the latest MGS data covering limited climatic and weather conditions at Mars, (b) to upgrade the 15-micron cooling and near-IR heating rates in the MGCM and MTGCM codes for ad- dressing climatic variations (solar cycle and seasonal) important in linking the lower and upper atmospheres (including migrating tides), and (c) to exercise the detailed coupled MGCM and MTGCM codes to capture and diagnose the planetary wave (migrating plus non-migrating tidal) features throughout the Mars year. Products from this new suite of MGCM-MTGCM coupled simulations are being used to improve our predictions of the structure of the Mars upper atmosphere for the upcoming MRO aerobraking exercises in 2006. A Michigan website, containing MTGCM output fields from previous climate simulations, is being expanded to include new MGCM-MTGCM simulations addressing planetary wave influences upon thermospheric aerobraking fields (densities and temperatures). In addition, similar MTGCM output fields have been supplied to the MSFC MARSGRAM - 200X empirical model, which will be used in mission operations for conducting aerobraking maneuvers.
Ionisation in ultra-cool, cloud forming extrasolar planetary atmospheres

NASA Astrophysics Data System (ADS)

Helling, Christiane; the LEAP Team

2015-04-01

Transit spectroscopy provides evidence that extrasolare planets are covered in clouds, a finding that has been forecast by cloud model simulations 15 years ago. Atmospheres are strongly affected by clouds through their large opacity and their chemical activity. Cloud formation models allow to predict cloud particle sizes, their chemical composition and the composition of the remaining atmospheric gas (Woitke & Helling 2004, A&A 414; Helling & Woitke 2006, A&A 455), for example, as input for radiative transfer codes like Drift-Phoenix (Witte et al. 2009; A&A 506). These cloud particles are charged and can discharge, for example in form of lighting (Helling et al. 2013, ApJ 767; Bailey et al. 2014, ApJ 784). Earth observations demonstrate that lighting effects not only the local chemistry but also the electron budget of the atmosphere. This talk will present our work on cloud formation modelling and ionisation processes in cloud forming atmospheres. An hierarchy of ionisation processes leads to a vertically inhomogenously ionised atmosphere which has implications for planetary mass loss and global circulation pattern of planetary atmospheres. Processes involved, like Cosmic Ray ionisation, do also activate the local chemistry such that large hydrocarbon molecules form (Rimmer et al. 2014, IJAsB 13).
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, P. G.

1985-01-01

Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and Earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often lead to significant misinterpretation of available opacity data. Steffes and Eshleman showed that under environmental conditions corresponding to the middle atmosphere of Venus, the microwave absorption due to atmospheric SO2 was 50 percent greater than that calculated from Van Vleck-Weiskopff theory. Similarly, the opacity from gaseous H2SO4 was found to be a factor of 7 greater than theoretically predicted for conditions of the Venus middle atmosphere. The recognition of the need to make such measurements over a range of temperatures and pressures which correspond to the periapsis altitudes of radio occultation experiments, and over a range of frequencies which correspond to both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements.
Laboratory Studies of Planetary Hazes: composition of cool exoplanet atmospheric aerosols with very high resolution mass spectrometry

NASA Astrophysics Data System (ADS)

Moran, Sarah E.; Horst, Sarah; He, Chao; Flandinet, Laurene; Moses, Julianne I.; Orthous-Daunay, Francois-Regis; Vuitton, Veronique; Wolters, Cedric; Lewis, Nikole

2017-10-01

We present first results of the composition of laboratory-produced exoplanet haze analogues. With the Planetary HAZE Research (PHAZER) Laboratory, we simulated nine exoplanet atmospheres of varying initial gas phase compositions representing increasing metallicities (100x, 1000x, and 10000x solar) and exposed them to three different temperature regimes (600, 400, and 300 K) with two different “instellation” sources (a plasma source and a UV lamp). The PHAZER exoplanet experiments simulate a temperature and atmospheric composition phase space relevant to the expected planetary yield of the Transiting Exoplanet Survey Satellite (TESS) mission as well as recently discovered potentially habitable zone exoplanets in the TRAPPIST-1, LHS-1140, and Proxima Centauri systems. Upon exposure to the energy sources, all of these experiments produced aerosol particles, which were collected in a dry nitrogen glove box and then analyzed with an LTQ Orbitrap XL™ Hybrid Ion Trap-Orbitrap Mass Spectrometer utilizing m/z ranging from 50 to 1000. The collected aerosol samples were found to contain complex organics. Constraining the composition of these aerosols allows us to better understand the photochemical and dynamical processes ongoing in exoplanet atmospheres. Moreover, these data can inform our telescope observations of exoplanets, which is of critical importance as we enter a new era of exoplanet atmosphere observation science with the upcoming launch of the James Webb Space Telescope. The molecular makeup of these haze particles provides key information for understanding exoplanet atmospheric spectra, and constraining the structure and behavior of clouds, hazes, and other aerosols is at the forefront of exoplanet atmosphere science.
Europlanet-RI IDIS - A Data Network in Support of Planetary Research

NASA Astrophysics Data System (ADS)

Schmidt, Walter; Capria, Maria Teresa; Chanteur, Gérard

2010-05-01

The "Europlanet Research Infrastructure - Europlanet RI", supported by the European Commission's Framework Program 7, aims at integrating major parts of the distributed European Planetary Research infrastructure with as diverse components as space exploration, ground-based observations, laboratory experiments and numerical modeling teams. A central part of Europlanet RI is the "Integrated and Distributed Information Service" (IDIS), a network of data and information access facilities in Europe via which information relevant for planetary research can be easily found and retrieved. This covers the wide range from contact addresses of possible research partners, laboratories and test facilities to the access of data collected with space missions or during laboratory or simulation tests and to model software useful for their interpretation. During the following three years the capabilities of the network will be extended to allow the combination of many different data sources for comperative studies including the results of modeling calculations and simulations of instrument observations. Together with the access to complex databases for spectra of atmospheric molecules and planetary surface material IDIS will offer a versatile working environment for making the scientific exploitation of the resources put into planetary research in the past and future more effective. Many of the mentioned capabilities are already available now. List of contact web-sites: Technical node for support and management aspects: http://www.idis.europlanet-ri.eu/ Planetary Surfaces and Interiors node: http://www.idis-interiors.europlanet-ri.eu/ Planetary Plasma node: http://www.idis-plasma.europlanet-ri.eu/ Planetary Atmospheres node: http://www.idis-atmos.europlanet-ri.eu/ Small Bodies and Dust node: http://www.idis-sbdn.europlanet-ri.eu/ Planetary Dynamics and Extraterrestrial Matter node: http://www.idis-dyn.europlanet-ri.eu/
Studying the Structure of Condensables Jupiter’s 24deg Jet

NASA Astrophysics Data System (ADS)

Flom, Abigail; Sankar, Ramanakumar; Palotai, Csaba J.; Dowling, Timothy E.

2017-10-01

Simulations of the atmospheres of Jovian planets can be used to check our current understanding of the physics of their atmospheres. Such studies have been performed in the past, but the development of cloud microphysics models allows us to gain new insight in how the clouds form and behave in areas of interest. This study conducts high resolution cloudy simulations of the 24 degree north high speed jet for a period of 200 days. The models were created using the Explicit Planetary Isentropic_Coordinate (EPIC) general circulation model (Dowling et al 1998, 2006) that includes full hydrological cycle for multiple condensible species (Palotai and dowling 2008, Palotai et al 2016). This builds off of work presented by our group last year at DPS. The simulations were run under various conditions again in order to test what parameters led to stable simulations. These results help describe which physical parameters can lead to stable high speed jets and how water and ammonia behave within these features. Reference: [1] T. Dowling, A. Fischer, P. Gierasch, J. Harrington, R. Lebeau, and C. Santori. The explicit planetary isentropic-coordinate (epic) atmospheric model. Icarus, 1998. [2] T. E. Dowling, M. E. Bradley, E. Colon, J. Kramer, R. P. LeBeau, G. C. H. Lee, T. I. Mattox, R. Morales-Juberias, C. J. Palotai, V. k. Parimi, and A. P. Showman. The epic atmospheric model with an isentropic/terrain-following hybrid vertical coordinate. Icarus, 182:259-273, may 2006.[3] C. Palotai and T. E. Dowling. Addition of water and ammonia cloud microphysics to the epic model. Icarus, 2008.[4] C. J. Palotai, R. P. Le Beau, R. Shankar, A. Flom, J. Lashley, and T. McCabe. A cloud microphysics model for the gas giant planets. In AAS/Division for Planetary Sciences Meeting Abstracts, 2016.
PBMC: Pre-conditioned Backward Monte Carlo code for radiative transport in planetary atmospheres

NASA Astrophysics Data System (ADS)

García Muñoz, A.; Mills, F. P.

2017-08-01

PBMC (Pre-Conditioned Backward Monte Carlo) solves the vector Radiative Transport Equation (vRTE) and can be applied to planetary atmospheres irradiated from above. The code builds the solution by simulating the photon trajectories from the detector towards the radiation source, i.e. in the reverse order of the actual photon displacements. In accounting for the polarization in the sampling of photon propagation directions and pre-conditioning the scattering matrix with information from the scattering matrices of prior (in the BMC integration order) photon collisions, PBMC avoids the unstable and biased solutions of classical BMC algorithms for conservative, optically-thick, strongly-polarizing media such as Rayleigh atmospheres.
Comparisons of planetary wave propagation to the upper atmosphere during stratospheric warming events at different QBO phases

NASA Astrophysics Data System (ADS)

Koval, Andrey V.; Gavrilov, Nikolai M.; Pogoreltsev, Alexander I.; Savenkova, Elena N.

2018-06-01

The dynamical coupling of the lower and upper atmosphere by planetary waves (PWs) is studied. Numerical simulations of planetary wave (PW) amplitudes during composite sudden stratospheric warming (SSW) events in January-February are made using a model of general circulation of the middle and upper atmosphere with initial and boundary conditions typical for the westerly and easterly phases of quasi-biennial oscillation (QBO). The changes in PW amplitudes in the middle atmosphere before, during and after SSW event for the different QBO phases are considered. Near the North Pole, the increase in the mean temperature during SSW reaches 10-30 K at altitudes 30-50 km for four pairs of the model runs with the eQBO and wQBO, which is characteristic for the sudden stratospheric warming event. Amplitudes of stationary PWs in the middle atmosphere of the Northern hemisphere may differ up to 30% during wQBO and eQBO before and during the SSW. After the SSW event SPW amplitudes are substantially larger during wQBO phase. PW refractivity indices and Eliassen-Palm flux vectors are calculated. The largest EP-fluxes in the middle atmosphere correspond to PWs with zonal wavenumber m=1. Simulated changes in PW amplitudes correspond to inhomogeneities of the global circulation, refractivity index and EP-flux produced by the changes in QBO phases. Comparisons of differences in PW characteristics and circulation between the wQBO and eQBO show that PWs could provide effective coupling mechanism and transport dynamical changes from local regions of the lower atmosphere to distant regions of the upper atmosphere of both hemispheres.
SPEX: the Spectropolarimeter for Planetary Exploration

NASA Astrophysics Data System (ADS)

Rietjens, J. H. H.; Snik, F.; Stam, D. M.; Smit, J. M.; van Harten, G.; Keller, C. U.; Verlaan, A. L.; Laan, E. C.; ter Horst, R.; Navarro, R.; Wielinga, K.; Moon, S. G.; Voors, R.

2017-11-01

We present SPEX, the Spectropolarimeter for Planetary Exploration, which is a compact, robust and low-mass spectropolarimeter designed to operate from an orbiting or in situ platform. Its purpose is to simultaneously measure the radiance and the state (degree and angle) of linear polarization of sunlight that has been scattered in a planetary atmosphere and/or reflected by a planetary surface with high accuracy. The degree of linear polarization is extremely sensitive to the microphysical properties of atmospheric or surface particles (such as size, shape, and composition), and to the vertical distribution of atmospheric particles, such as cloud top altitudes. Measurements as those performed by SPEX are therefore crucial and often the only tool for disentangling the many parameters that describe planetary atmospheres and surfaces. SPEX uses a novel, passive method for its radiance and polarization observations that is based on a carefully selected combination of polarization optics. This method, called spectral modulation, is the modulation of the radiance spectrum in both amplitude and phase by the degree and angle of linear polarization, respectively. The polarization optics consists of an achromatic quarter-wave retarder, an athermal multiple-order retarder, and a polarizing beam splitter. We will show first results obtained with the recently developed prototype of the SPEX instrument, and present a performance analysis based on a dedicated vector radiative transport model together with a recently developed SPEX instrument simulator.
Exo-Transmit: Radiative transfer code for calculating exoplanet transmission spectra

NASA Astrophysics Data System (ADS)

Kempton, Eliza M.-R.; Lupu, Roxana E.; Owusu-Asare, Albert; Slough, Patrick; Cale, Bryson

2016-11-01

Exo-Transmit calculates the transmission spectrum of an exoplanet atmosphere given specified input information about the planetary and stellar radii, the planet's surface gravity, the atmospheric temperature-pressure (T-P) profile, the location (in terms of pressure) of any cloud layers, the composition of the atmosphere, and opacity data for the atoms and molecules that make up the atmosphere. The code solves the equation of radiative transfer for absorption of starlight passing through the planet's atmosphere as it transits, accounting for the oblique path of light through the planetary atmosphere along an Earth-bound observer's line of sight. The fraction of light absorbed (or blocked) by the planet plus its atmosphere is calculated as a function of wavelength to produce the wavelength-dependent transmission spectrum. Functionality is provided to simulate the presence of atmospheric aerosols in two ways: an optically thick (gray) cloud deck can be generated at a user-specified height in the atmosphere, and the nominal Rayleigh scattering can be increased by a specified factor.
Recovering the colour-dependent albedo of exoplanets with high-resolution spectroscopy: from ESPRESSO to the ELT.

NASA Astrophysics Data System (ADS)

Martins, J. H. C.; Figueira, P.; Santos, N. C.; Melo, C.; Garcia Muñoz, A.; Faria, J.; Pepe, F.; Lovis, C.

2018-05-01

The characterization of planetary atmospheres is a daunting task, pushing current observing facilities to their limits. The next generation of high-resolution spectrographs mounted on large telescopes - such as ESPRESSO@VLT and HIRES@ELT - will allow us to probe and characterize exoplanetary atmospheres in greater detail than possible to this point. We present a method that permits the recovery of the colour-dependent reflectivity of exoplanets from high-resolution spectroscopic observations. Determining the wavelength-dependent albedo will provide insight into the chemical properties and weather of the exoplanet atmospheres. For this work, we simulated ESPRESSO@VLT and HIRES@ELT high-resolution observations of known planetary systems with several albedo configurations. We demonstrate how the cross correlation technique applied to theses simulated observations can be used to successfully recover the geometric albedo of exoplanets over a range of wavelengths. In all cases, we were able to recover the wavelength dependent albedo of the simulated exoplanets and distinguish between several atmospheric models representing different atmospheric configurations. In brief, we demonstrate that the cross correlation technique allows for the recovery of exoplanetary albedo functions from optical observations with the next generation of high-resolution spectrographs that will be mounted on large telescopes with reasonable exposure times. Its recovery will permit the characterization of exoplanetary atmospheres in terms of composition and dynamics and consolidates the cross correlation technique as a powerful tool for exoplanet characterization.
Monte Carlo simulation of nonadiabatic expansion in cometary atmospheres - Halley

NASA Astrophysics Data System (ADS)

Hodges, R. R.

1990-02-01

Monte Carlo methods developed for the characterization of velocity-dependent collision processes and ballistic transports in planetary exospheres form the basis of the present computer simulation of icy comet atmospheres, which iteratively undertakes the simultaneous determination of velocity distribution for five neutral species (water, together with suprathermal OH, H2, O, and H) in a flow regime varying from the hydrodynamic to the ballistic. Experimental data from the neutral mass spectrometer carried by Giotto for its March, 1986 encounter with Halley are compared with a model atmosphere.

The Threatening Magnetic and Plasma Environment of the TRAPPIST-1 Planets

NASA Astrophysics Data System (ADS)

Garraffo, Cecilia; Drake, Jeremy J.; Cohen, Ofer; Alvarado-Gómez, Julian D.; Moschou, Sofia P.

2017-07-01

Recently, four additional Earth-mass planets were discovered orbiting the nearby ultracool M8 dwarf, TRAPPIST-1, making a remarkable total of seven planets with equilibrium temperatures compatible with the presence of liquid water on their surface. Temperate terrestrial planets around an M-dwarf orbit close to their parent star, rendering their atmospheres vulnerable to erosion by the stellar wind and energetic electromagnetic and particle radiation. Here, we use state-of-the-art 3D magnetohydrodynamic models to simulate the wind around TRAPPIST-1 and study the conditions at each planetary orbit. All planets experience a stellar wind pressure between 103 and 105 times the solar wind pressure on Earth. All orbits pass through wind pressure changes of an order of magnitude and most planets spend a large fraction of their orbital period in the sub-Alfvénic regime. For plausible planetary magnetic field strengths, all magnetospheres are greatly compressed and undergo much more dynamic change than that of the Earth. The planetary magnetic fields connect with the stellar radial field over much of the planetary surface, allowing the direct flow of stellar wind particles onto the planetary atmosphere. These conditions could result in strong atmospheric stripping and evaporation and should be taken into account for any realistic assessment of the evolution and habitability of the TRAPPIST-1 planets.
Mechanisms driving the global and seasonal structure of the 16-day planetary wave

NASA Astrophysics Data System (ADS)

Nguyen, V.; Chang, L. C.; Liu, H.; Palo, S. E.

2013-12-01

Past observations have shown that the effects of the quasi 16-day planetary wave, representing the second symmetric Rossby normal mode, are prevalent throughout the middle atmosphere and occasionally, some portions of the upper atmosphere. In the presented work, we investigate the mechanisms driving the propagation of the quasi 16-day planetary wave from a source in the lower atmosphere to higher altitudes by using the NCAR Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM). The quasi 16-day planetary wave is simulated in the model by introducing perturbations in geopotential height at the lower boundary of the model and comparing it to a control run. Analysis of the model runs over the course of a year show that the background zonal winds play an important role in driving seasonal changes in the quasi 16-day planetary wave structure. Derived quasi-geostrophic potential vorticity gradient and Eliassen-Palm flux from the model output also show that the penetration of the wave into regions of mean wind instability can drive wave amplification in certain regions. The model results are compared to the quasi 16-day wave structure derived from TIMED-SABER observations to identify similarities/differences between the model and observations, and provide further insight into the mechanisms driving the wave propagation.
Simulating land-atmosphere feedbacks and response to widespread forest disturbance: The role of lower boundary configuration and dynamic water table in meteorological modeling

NASA Astrophysics Data System (ADS)

Forrester, M.; Maxwell, R. M.; Bearup, L. A.; Gochis, D.

2017-12-01

Numerical meteorological models are frequently used to diagnose land-atmosphere interactions and predict large-scale response to extreme or hazardous events, including widespread land disturbance or perturbations to near-surface moisture. However, few atmospheric modeling platforms consider the impact that dynamic groundwater storage, specifically 3D subsurface flow, has on land-atmosphere interactions. In this study, we use the Weather Research and Forecasting (WRF) mesoscale meteorological model to identify ecohydrologic and land-atmosphere feedbacks to disturbance by the mountain pine beetle (MPB) over the Colorado Headwaters region. Disturbance simulations are applied to WRF with various lower boundary configurations: Including default Noah land surface model soil moisture representation; a version of WRF coupled to ParFlow (PF), an integrated groundwater-surface water model that resolves variably saturated flow in the subsurface; and WRF coupled to PF in a static water table version, simulating only vertical and no lateral subsurface flow. Our results agree with previous literature showing MPB-induced reductions in canopy transpiration in all lower boundary scenarios, as well as energy repartitioning, higher water tables, and higher planetary boundary layer over infested regions. Simulations show that expanding from local to watershed scale results in significant damping of MPB signal as unforested and unimpacted regions are added; and, while deforestation appears to have secondary feedbacks to planetary boundary layer and convection, these slight perturbations to cumulative summer precipitation are insignificant in the context of ensemble methodologies. Notably, the results suggest that groundwater representation in atmospheric modeling affects the response intensity of a land disturbance event. In the WRF-PF case, energy and atmospheric processes are more sensitive to disturbance in regions with higher water tables. Also, when dynamic subsurface hydrology is removed, WRF simulates a greater response to MPB at the land-atmosphere interface, including greater changes to daytime skin temperature, Bowen ratio and near-surface humidity. These findings highlight lower boundary representations in computational meteorology and numerical land-atmosphere modeling.
Intercomparison of Martian Lower Atmosphere Simulated Using Different Planetary Boundary Layer Parameterization Schemes

NASA Technical Reports Server (NTRS)

Natarajan, Murali; Fairlie, T. Duncan; Dwyer Cianciolo, Alicia; Smith, Michael D.

2015-01-01

We use the mesoscale modeling capability of Mars Weather Research and Forecasting (MarsWRF) model to study the sensitivity of the simulated Martian lower atmosphere to differences in the parameterization of the planetary boundary layer (PBL). Characterization of the Martian atmosphere and realistic representation of processes such as mixing of tracers like dust depend on how well the model reproduces the evolution of the PBL structure. MarsWRF is based on the NCAR WRF model and it retains some of the PBL schemes available in the earth version. Published studies have examined the performance of different PBL schemes in NCAR WRF with the help of observations. Currently such assessments are not feasible for Martian atmospheric models due to lack of observations. It is of interest though to study the sensitivity of the model to PBL parameterization. Typically, for standard Martian atmospheric simulations, we have used the Medium Range Forecast (MRF) PBL scheme, which considers a correction term to the vertical gradients to incorporate nonlocal effects. For this study, we have also used two other parameterizations, a non-local closure scheme called Yonsei University (YSU) PBL scheme and a turbulent kinetic energy closure scheme called Mellor- Yamada-Janjic (MYJ) PBL scheme. We will present intercomparisons of the near surface temperature profiles, boundary layer heights, and wind obtained from the different simulations. We plan to use available temperature observations from Mini TES instrument onboard the rovers Spirit and Opportunity in evaluating the model results.
Twenty-Fourth Lunar and Planetary Science Conference. Part 2: G-M

NASA Technical Reports Server (NTRS)

1993-01-01

The topics covered include the following: meteorites, meteoritic composition, geochemistry, planetary geology, planetary composition, planetary craters, the Moon, Mars, Venus, asteroids, planetary atmospheres, meteorite craters, space exploration, lunar geology, planetary surfaces, lunar surface, lunar rocks, lunar soil, planetary atmospheres, lunar atmosphere, lunar exploration, space missions, geomorphology, lithology, petrology, petrography, planetary evolution, Earth surface, planetary surfaces, volcanology, volcanos, lava, magma, mineralogy, minerals, ejecta, impact damage, meteoritic damage, tectonics, etc.
Photochemical Formation of Sulfur-Containing Aerosols

NASA Astrophysics Data System (ADS)

Kroll, Jay A.; Vaida, Veronica

2017-06-01

In order to understand planetary climate systems, modeling the properties of atmospheric aerosols is vital. Aerosol formation plays an important role in planetary climates and is tied to feedback loops that can either warm or cool a planet. Sulfur compounds are known to play an important role in new particle aerosol formation and have been observed in a number of planetary atmospheres throughout our solar system. Our current understanding of sulfur chemistry explains much of what we observe in Earth's atmosphere; however, several discrepancies arise when comparing observations of the Venusian atmosphere with model predictions. This suggests that there are still problems in our fundamental understanding of sulfur chemistry. This is concerning given recent renewed interest in sulfate injections in the stratosphere for solar radiation management geo-engineering schemes. We investigate the role of sunlight as a potential driver of the formation of sulfur-containing aerosols. I will present recent work investigating the generation of large quantities of aerosol from the irradiation of mixtures of SO_2 with water and organic species, using a solar simulator that mimics the light that is available in the Earth's troposphere and the Venusian middle atmosphere. I will present on recent work done in our lab suggesting the formation of sulfurous acid, H_2SO_3, and describe experimental work that supports this proposed mechanism. Additionally I will present on new work showing the highly reactive nature of electronically excited SO_2 with saturated alkane species. The implications of this photochemically induced sulfur aerosol formation in the atmosphere of Earth and other planetary atmospheres will be discussed.
A Simulation Model of the Planetary Boundary Layer at Kennedy Space Center

NASA Technical Reports Server (NTRS)

Hwang, B.

1978-01-01

A simulation model which predicts the behavior of the Atmospheric Boundary Layer has been developed and coded. The model is partially evaluated by comparing it with laboratory measurements and the sounding measurements at Kennedy Space Center. The applicability of such an approach should prove quite widespread.
Formation and Internal Structure of Terrestrial Planets, and Atmospheric Escape

NASA Astrophysics Data System (ADS)

Jin, S.

2014-11-01

As of 2014 April 21, over 1490 confirmed exoplanets and 3705 Kepler candidates have been detected. This implies that exoplanets may be ubiquitous in the universe. In this paper, we focus on the formation, evolution, and internal structure of terrestrial planets, and the atmospheric escape of close-in planets. In chapter 2, we investigate the dynamical evolution of planetary system after the protoplanetary disk has dissipated. We find that in the final assembly stage, the occurrence of terrestrial planets is quite common and in 40% of our simulations finally at least one planet is formed in the habitable zone. We also find that if there is a highly-inclined giant planet in the system, a great many bodies will be either driven out of the system, or collide with the giant planet or the central star. This will lead to the difficulty in planetary accretion. Moreover, our results show that planetary migration can lead to the formation of close-in planets. Besides migration, close-in terrestrial planets can also be formed by a collision-merger mechanism, which means that planetary embryos can kick terrestrial planets directly into orbits that are extremely close to their parent stars. In chapter 3, we construct numerically an internal structure model for terrestrial planets, and provide three kinds of possible internal structures of Europa (Jupiter's moon) based on this model. Then, we calculate the radii of low-mass exoplanets for various mass combinations of core and mantle, and find that some of them are inconsistent with the observed radius of rocky planets. This phenomenon can be explained only if there exists a large amount of water in the core, or they own gaseous envelopes. In chapter 4, we improve our planetary evolution codes using the semi-gray model of Guillot (2010), which includes the incident flux from the host star as a heating source in planetary atmosphere. The updated codes can solve the structure of the top radiative zone of intensely irradiated planets, and thus can simulate the atmospheric escape of close-in planets driven by strong stellar X-ray or EUV emissions. We find that low-mass planets are sensitive to the atmospheric escape, and they could lose all their initial H/He envelopes during the evolution. On the other hand, gas giant can only lose a small fraction of their initial envelopes. We then carry out a parameter study of atmospheric escape at the planetary core mass, envelope mass fraction, and semi-major axis space. We find that the most intense phase of evaporation occurs within the early 100 Myr. Afterwards, atmospheric escape only has a small impact on the planetary evolution. In chapter 5, we apply our new planetary evolution model to different synthetic planet populations that are directly produced by the core-accretion paradigm (Mordasini et al. 2012a,b). We show that although the mass distribution of the planet populations is hardly affected by evaporation, the radius distribution clearly shows a break around 2 R_{⊕}. This break leads to a bimodal distribution in planet sizes (Owen & Wu 2013). Furthermore, the bimodal distribution is related to the initial characteristics of the planetary populations. We find that in two extreme cases, namely without any evaporation or with a 100% heating efficiency in the evaporation model, the final radius distributions show significant differences compared to the radius distribution of Kepler candidates. In chapter 6, we introduce a radiative transfer model that can calculate the radiation spectrum of close-in exoplanets.
Probing the Physics and Chemistry in Hot Jupiter Exoclimes for Future Missions

NASA Astrophysics Data System (ADS)

Afrin Badhan, Mahmuda; Kopparapu, Ravi Kumar; Domagal-Goldman, Shawn; Deming, Drake; Hébrard, Eric; Irwin, Patrick GJ; Batalha, Natasha; Mandell, Avi

2017-01-01

Unique and exotic planets give us an opportunity to understand how planetary systems form and evolve over their lifetime, by placing our own planetary system in the context of vastly different extrasolar systems. In particular, close-in planets such as Hot Jupiters provide us with valuable insights about the host stellar atmosphere and planetary atmospheres subjected to such high levels of stellar insolation. Observed spectroscopic signatures from a planet reveal all spectrally active species in its atmosphere, along with information about its thermal structure and dynamics, allowing us to characterize the planet's atmosphere. NASA’s upcoming missions will give us the high-resolution spectra necessary to constrain such atmospheric properties with unprecedented accuracy. However, to interpret the observed signals from exoplanetary transit events with any certainty, we need reliable atmospheric modeling tools that map both the physical and chemical processes affecting the particular type of planet under investigation. My work seeks to expand on past efforts in these two categories for irradiated giant exoplanets. These atmospheric models can be combined with future mission simulations to build tools that allow us to self-consistently “retrieve” the signatures we can expect to observe with the instruments. In my work thus far, I have built the robust Markov Chain Monte Carlo convergence scheme, with an analytical radiative equilibrium formulation to represent the thermal structures, within the NEMESIS atmospheric radiative transfer modeling and retrieval tool. I have combined this physics-based thermal structure with photochemical abundance profiles for the major gas atmospheric constituents, using the NASA Astrobiology Institute’s VPL/Atmos photochemistry model, which I recently extended to giant planet regimes. Here I will present my new Hot Jupiter models and retrievals results constructed from these latest enhancements. For comparison, I will show applications to both archival data from present missions and JWST/NIRSpec simulations, and discuss any new information we expect to reliably extract from the upcoming JWST mission.
Simulated orbits of heavy planetary ions at Mars for different IMF configurations

NASA Astrophysics Data System (ADS)

Curry, Shannon; Luhmann, Janet; Livi, Roberto; Hara, Takuya; Dong, Chuanfei; Ma, Yingjuan; McFadden, James; Bougher, Stephen

2014-11-01

We present simulated detections of O+, O2+ and CO2+ ions at Mars along a virtual orbit in the Mars space environment. Planetary pick-up ions are formed through the direct interaction of the solar wind with the neutral upper atmosphere, causing the newly created ions to be picked up and accelerated by the background convective electric field. Because previous missions such as Mars Global Surveyor (MGS) and Mars Express (MEX) have not been able to measure the interplanetary magnetic field (IMF) components simultaneously with plasma measurements, the response of heavy planetary pick-up ions to changes in the IMF has not been well characterized. Using a steady-state multi-species MHD model to provide the background electric and magnetic fields, the Mars Test Particle (MTP) simulation can trace each of these particles along field lines in near-Mars space and construct virtual ion detections from a spacecraft orbit. Specifically, we will present energy-time spectrograms and velocity space distributions (VSDs) for a selection of orbits during different IMF configurations and solar cycle conditions. These simulated orbits have broader implications for how to measure ion escape. Using individual particle traces, the origin and trajectories of different ion populations can be analyzed in order to assess how and where they contribute to the total atmospheric escape rate, which is a major objective of the upcoming MAVEN mission.
Twenty-Fourth Lunar and Planetary Science Conference. Part 2: G-M

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-01-01

The topics covered include the following: meteorites, meteoritic composition, geochemistry, planetary geology, planetary composition, planetary craters, the Moon, Mars, Venus, asteroids, planetary atmospheres, meteorite craters, space exploration, lunar geology, planetary surfaces, lunar surface, lunar rocks, lunar soil, planetary atmospheres, lunar atmosphere, lunar exploration, space missions, geomorphology, lithology, petrology, petrography, planetary evolution, Earth surface, planetary surfaces, volcanology, volcanos, lava, magma, mineralogy, minerals, ejecta, impact damage, meteoritic damage, tectonics, etc. Separate abstracts have been prepared for articles from this report.
On ion escape from Venus

NASA Astrophysics Data System (ADS)

Jarvinen, R.

2011-04-01

This doctoral thesis is about the solar wind influence on the atmosphere of the planet Venus. A numerical plasma simulation model was developed for the interaction between Venus and the solar wind to study the erosion of charged particles from the Venus upper atmosphere. The developed model is a hybrid simulation where ions are treated as particles and electrons are modelled as a fluid. The simulation was used to study the solar wind induced ion escape from Venus as observed by the European Space Agency's Venus Express and NASA's Pioneer Venus Orbiter spacecraft. Especially, observations made by the ASPERA-4 particle instrument onboard Venus Express were studied. The thesis consists of an introductory part and four peer-reviewed articles published in scientific journals. In the introduction Venus is presented as one of the terrestrial planets in the Solar System and the main findings of the work are discussed within the wider context of planetary physics.Venus is the closest neighbouring planet to the Earth and the most earthlike planet in its size and mass orbiting the Sun. Whereas the atmosphere of the Earth consists mainly of nitrogen and oxygen, Venus has a hot carbon dioxide atmosphere, which is dominated by the greenhouse effect. Venus has all of its water in the atmosphere, which is only a fraction of the Earth's total water supply. Since planets developed presumably in similar conditions in the young Solar System, why Venus and Earth became so different in many respects?One important feature of Venus is that the planet does not have an intrinsic magnetic field. This makes it possible for the solar wind, a continuous stream of charged particles from the Sun, to flow close to Venus and to pick up ions from the planet's upper atmosphere. The strong intrinsic magnetic field of the Earth dominates the terrestrial magnetosphere and deflects the solar wind flow far away from the atmosphere. The region around Venus where the planet's atmosphere interacts with the solar wind is called the plasma environment or the induced magnetosphere.Main findings of the work include new knowledge about the movement of escaping planetary ions in the Venusian induced magnetosphere. Further, the developed simulation model was used to study how the solar wind conditions affect the ion escape from Venus. Especially, the global three-dimensional structure of the Venusian particle and magnetic environment was studied. The results help to interpret spacecraft observations around the planet. Finally, several remaining questions were identified, which could potentially improve our knowledge of the Venus ion escape and guide the future development of planetary plasma simulations.
On ion escape from Venus

NASA Astrophysics Data System (ADS)

Jarvinen, Riku

2011-04-01

This doctoral thesis is about the solar wind influence on the atmosphere of the planet Venus. A numerical plasma simulation model was developed for the interaction between Venus and the solar wind to study the erosion of charged particles from the Venus upper atmosphere. The developed model is a hybrid simulation where ions are treated as particles and electrons are modelled as a fluid. The simulation was used to study the solar wind induced ion escape from Venus as observed by the European Space Agency's Venus Express and NASA's Pioneer Venus Orbiter spacecraft. Especially, observations made by the ASPERA-4 particle instrument onboard Venus Express were studied. The thesis consists of an introductory part and four peer-reviewed articles published in scientific journals. In the introduction Venus is presented as one of the terrestrial planets in the Solar System and the main findings of the work are discussed within the wider context of planetary physics. Venus is the closest neighbouring planet to the Earth and the most earthlike planet in its size and mass orbiting the Sun. Whereas the atmosphere of the Earth consists mainly of nitrogen and oxygen, Venus has a hot carbon dioxide atmosphere, which is dominated by the greenhouse effect. Venus has all of its water in the atmosphere, which is only a fraction of the Earth's total water supply. Since planets developed presumably in similar conditions in the young Solar System, why Venus and Earth became so different in many respects? One important feature of Venus is that the planet does not have an intrinsic magnetic field. This makes it possible for the solar wind, a continuous stream of charged particles from the Sun, to flow close to Venus and to pick up ions from the planet's upper atmosphere. The strong intrinsic magnetic field of the Earth dominates the terrestrial magnetosphere and deflects the solar wind flow far away from the atmosphere. The region around Venus where the planet's atmosphere interacts with the solar wind is called the plasma environment or the induced magnetosphere. Main findings of the work include new knowledge about the movement of escaping planetary ions in the Venusian induced magnetosphere. Further, the developed simulation model was used to study how the solar wind conditions affect the ion escape from Venus. Especially, the global three-dimensional structure of the Venusian particle and magnetic environment was studied. The results help to interpret spacecraft observations around the planet. Finally, several remaining questions were identified, which could potentially improve our knowledge of the Venus ion escape and guide the future development of planetary plasma simulations.
Exobiology and the origin of life. [organic compounds in planetary atmospheres and interstellar matter

NASA Technical Reports Server (NTRS)

Sagan, C.

1978-01-01

Research supported wholly or in part by NASA is summarized, Topics covered include the molecular analysis of ultraviolet-photoproduced organic solids synthesized under simulated Jovian conditions; the molecular analysis of organic solids produced by electrical discharge in reducing atmospheres; the organic chemistry of interstellar grains; the spectra of possible organic solids present as aerosols in planetary atmospheres; far infrared studies of organic polymers of possible astrophysical interest; organic dust synthesized in reducing environments by ultraviolet radiation or electric discharge; the diffusion of galactic civilizations; eavesdropping on galactic civilizations; Lander imaging as a detector of life on Mars; and continuing puzzles about Mars. Bibliographic data is included for four additional publications not supported by NASA grant, but related to the objectives of the program.
Radiative transfer in a polluted urban planetary boundary layer

NASA Technical Reports Server (NTRS)

Viskanta, R.; Johnson, R. O.; Bergstrom, R. W.

1977-01-01

Radiative transfer in a polluted urban atmosphere is studied using a dynamic model. The diurnal nature of radiative transfer for summer conditions is simulated for an urban area 40 km in extent and the effects of various parameters arising in the problem are investigated. The results of numerical computations show that air pollution has the potential of playing a major role in the radiative regime of the urban area. Absorption of solar energy by aerosols in realistic models of urban atmosphere are of the same order of magnitude as that due to water vapor. The predicted effect of the air pollution aerosol in the city is to warm the earth-atmosphere system, and the net effect of gaseous pollutant is to warm the surface and cool the planetary boundary layer, particularly near the top.
The Threatening Magnetic and Plasma Environment of the TRAPPIST-1 Planets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garraffo, Cecilia; Drake, Jeremy J.; Cohen, Ofer

2017-07-10

Recently, four additional Earth-mass planets were discovered orbiting the nearby ultracool M8 dwarf, TRAPPIST-1, making a remarkable total of seven planets with equilibrium temperatures compatible with the presence of liquid water on their surface. Temperate terrestrial planets around an M-dwarf orbit close to their parent star, rendering their atmospheres vulnerable to erosion by the stellar wind and energetic electromagnetic and particle radiation. Here, we use state-of-the-art 3D magnetohydrodynamic models to simulate the wind around TRAPPIST-1 and study the conditions at each planetary orbit. All planets experience a stellar wind pressure between 10{sup 3} and 10{sup 5} times the solar windmore » pressure on Earth. All orbits pass through wind pressure changes of an order of magnitude and most planets spend a large fraction of their orbital period in the sub-Alfvénic regime. For plausible planetary magnetic field strengths, all magnetospheres are greatly compressed and undergo much more dynamic change than that of the Earth. The planetary magnetic fields connect with the stellar radial field over much of the planetary surface, allowing the direct flow of stellar wind particles onto the planetary atmosphere. These conditions could result in strong atmospheric stripping and evaporation and should be taken into account for any realistic assessment of the evolution and habitability of the TRAPPIST-1 planets.« less
Photochemical Haze Formation in the Atmospheres of Super-Earths and Mini-Neptunes

NASA Technical Reports Server (NTRS)

He, Chao; Hoerst, Sarah M.; Lewis, Nikole K.; Yu, Xinting; Moses, Julianne I.; Kempton, Eliza M.- R.; Marley, Mark S.; McGuiggan, Patricia; Morley, Caroline V.; Valenti, Jeff A.;

2018-01-01

UV (ultraviolet) radiation can induce photochemical processes in the atmospheres of exoplanet and produce haze particles. Recent transmission spectra of super-Earths and mini-Neptunes have demonstrated the possibility that exoplanets have haze/cloud layers at high altitudes in their atmospheres. Haze particles play an important role in planetary atmospheres because they affect the chemistry, dynamics, and radiation flux in planetary atmospheres, and may provide a source of organic material to the surface which may impact the origin or evolution of life. However, very little information is known about photochemical processes in cool, high-metallicity exoplanetary atmospheres. We present here photochemical haze formation in laboratory simulation experiments with UV radiation; we explored temperatures ranging from 300 to 600 degrees Kelvin and a range of atmospheric metallicities (100 times, 1000 times, and 10000 times solar metallicity). We find that photochemical hazes are generated in all simulated atmospheres, but the haze production rates appear to be temperature dependent: the particles produced in each metallicity group decrease as the temperature increases. The images taken with an atomic force microscope (AFM) show that the particle size (15 nanometers to 190 nanometers) varies with temperature and metallicity. Our results provide useful laboratory data on the photochemical haze formation and particle properties, which can serve as critical inputs for exoplanet atmosphere modeling, and guide future observations of exoplanets with the Transiting Exoplanet Survey Satellite (TESS), the James Webb Space Telescope (JWST), and the Wide-Field Infrared Survey Telescope (WFIRST).

Young planets under extreme UV irradiation. I. Upper atmosphere modelling of the young exoplanet K2-33b

NASA Astrophysics Data System (ADS)

Kubyshkina, D.; Lendl, M.; Fossati, L.; Cubillos, P. E.; Lammer, H.; Erkaev, N. V.; Johnstone, C. P.

2018-04-01

The K2-33 planetary system hosts one transiting 5 R⊕ planet orbiting the young M-type host star. The planet's mass is still unknown, with an estimated upper limit of 5.4 MJ. The extreme youth of the system (<20 Myr) gives the unprecedented opportunity to study the earliest phases of planetary evolution, at a stage when the planet is exposed to an extremely high level of high-energy radiation emitted by the host star. We perform a series of 1D hydrodynamic simulations of the planet's upper atmosphere considering a range of possible planetary masses, from 2 to 40 M⊕, and equilibrium temperatures, from 850 to 1300 K, to account for internal heating as a result of contraction. We obtain temperature profiles mostly controlled by the planet's mass, while the equilibrium temperature has a secondary effect. For planetary masses below 7-10 M⊕, the atmosphere is subject to extremely high escape rates, driven by the planet's weak gravity and high thermal energy, which increase with decreasing mass and/or increasing temperature. For higher masses, the escape is instead driven by the absorption of the high-energy stellar radiation. A rough comparison of the timescales for complete atmospheric escape and age of the system indicates that the planet is more massive than 10 M⊕.
Further Development of Verification Check-Cases for Six- Degree-of-Freedom Flight Vehicle Simulations

NASA Technical Reports Server (NTRS)

Jackson, E. Bruce; Madden, Michael M.; Shelton, Robert; Jackson, A. A.; Castro, Manuel P.; Noble, Deleena M.; Zimmerman, Curtis J.; Shidner, Jeremy D.; White, Joseph P.; Dutta, Doumyo;

2015-01-01

This follow-on paper describes the principal methods of implementing, and documents the results of exercising, a set of six-degree-of-freedom rigid-body equations of motion and planetary geodetic, gravitation and atmospheric models for simple vehicles in a variety of endo- and exo-atmospheric conditions with various NASA, and one popular open-source, engineering simulation tools. This effort is intended to provide an additional means of verification of flight simulations. The models used in this comparison, as well as the resulting time-history trajectory data, are available electronically for persons and organizations wishing to compare their flight simulation implementations of the same models.

Simulating planetary wave propagation to the upper atmosphere during stratospheric warming events at different mountain wave scenarios

NASA Astrophysics Data System (ADS)

Gavrilov, Nikolai M.; Koval, Andrey V.; Pogoreltsev, Alexander I.; Savenkova, Elena N.

2018-04-01

Parameterization schemes of atmospheric normal modes (NMs) and orographic gravity waves (OGWs) have been implemented into the mechanistic Middle and Upper Atmosphere Model (MUAM) simulating atmospheric general circulation. Based on the 12-members ensemble of runs with the MUAM, a composite of the stratospheric warming (SW) has been constructed using the UK Met Office data as the lower boundary conditions. The simulation results show that OGW amplitudes increase at altitudes above 30 km in the Northern Hemisphere after the SW event. At altitudes of about 50 km, OGWs have largest amplitudes over North American and European mountain systems before and during the composite SW, and over Himalayas after the SW. Simulations demonstrate substantial (up to 50-70%) variations of amplitudes of stationary planetary waves (PWs) during and after the SW in the mesosphere-lower thermosphere of the Northern Hemisphere. Westward travelling NMs have amplitude maxima not only in the Northern, but also in the Southern Hemisphere, where these modes have waveguides in the middle and upper atmosphere. Simulated variations of PW and NM amplitudes correspond to changes in the mean zonal wind, EP-fluxes and wave refractive index at different phases of the composite SW events. Inclusion of the parameterization of OGW effects leads to decreases in amplitudes (up to 15%) of almost all SPWs before and after the SW event and their increase (up to 40-60%) after the SW in the stratosphere and mesosphere at middle and high northern latitudes. It is suggested that observed changes in NM amplitudes in the Southern Hemisphere during SW could be caused by divergence of increased southward EP-flux. This EP-flux increases due to OGW drag before SW and extends into the Southern Hemisphere.

Mars ecopoiesis test bed: on earth and on the red planet

NASA Astrophysics Data System (ADS)

Todd, Paul; Kurk, Michael Andy; Boland, Eugene; Thomas, David; Scherzer, Christopher

2016-07-01

The concept of autotrophic organisms serving as planetary pioneers as a precursor to terraforming has been under consideration for several decades, and the term Ecopoiesis was introduced by the ecopoiets C. Sagan, M. Avener, R. Haynes and C. McKay to call attention to this possibility. There is a continuing need for experimental evidence to support this concept, one of them being the need to evaluate the survivability of terrestrial autotrophic microbes in a planetary environment. For this and other purposes a planetary simulation facility was constructed and operated at Techshot, Inc. in Indiana, USA. This facility has an accumulated record of more than one year's worth of experimentation under simulated Mars conditions. In a recent study this facility was operated for five weeks in a mode that simulated 35 sols on and just below the surface of Mars at low latitude. The diurnal lighting period was 12 hours:12 hours using xenon arc light filtered to simulate the solar intensity and spectrum on the Martian surface. A daily temperature profile followed that recorded at low latitudes with night-time minima at -80 C and noontime maxima at +26 C. Atmosphere was CO _{2} at <11 mbar. Moisture was monitored to confirm that no water could exist in the liquid phase. Test organisms included the cyanobacteria Anabena, sp., Chroococcidiopsis CCMEE171 and Plectonema boryanum and Eukaryota: Chlorella ellipsoidia maintained in the simulator under the above-described conditions. The exposed specimens were tested for intracellular esterase activity, chlorophyll content and reproductive survival. All tests yielded low-level positive survival results for these organisms. No definitive data relating to function and/or growth during exposure were sought. In parallel to these terrestrial studies a planned design study was undertaken for a proposed test bed to be operated on the surface of Mars. Design requirements include compact assembly for transport and installation on the planetary surface (multiple units per mission would be expected), protective internal package for the release of organisms, a means of atmosphere exchange, access to sunlight, a means of penetrating the planetary surface, and most importantly a means of acquiring regolith while meeting requirements of planetary protection. An enlarged-scale mock-up of this design was fabricated by additive manufacturing with moving parts that simulate the components of the design. This mock-up assembly marks a starting point for a planetary surface probe for safe implantation on the surface of the Red Planet some decades in the future. This research was supported by NASA NIAC Phase I Grant "Mars Ecopoiesis Testbed" NNX14AM97G.
Arctic Climate and Atmospheric Planetary Waves

NASA Technical Reports Server (NTRS)

Cavalieri, D. J.; Haekkinen, S.

2000-01-01

Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave I pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach to determine significant forcing patterns of sea ice and high-latitude variability.
The resistance of the lichen Circinaria gyrosa (nom. provis.) towards simulated Mars conditions—a model test for the survival capacity of an eukaryotic extremophile

NASA Astrophysics Data System (ADS)

Sánchez, F. J.; Mateo-Martí, E.; Raggio, J.; Meeßen, J.; Martínez-Frías, J.; Sancho, L. G.^a..; Ott, S.; de la Torre, R.

2012-11-01

The "Planetary Atmospheres and Surfaces Chamber" (PASC, at Centro de Astrobiología, INTA, Madrid) is able to simulate the atmosphere and surface temperature of most of the solar system planets. PASC is especially appropriate to study irradiation induced changes of geological, chemical, and biological samples under a wide range of controlled atmospheric and temperature conditions. Therefore, PASC is a valid method to test the resistance potential of extremophile organisms under diverse harsh conditions and thus assess the habitability of extraterrestrial environments. In the present study, we have investigated the resistance of a symbiotic organism under simulated Mars conditions, exemplified with the lichen Circinaria gyrosa - an extremophilic eukaryote. After 120 hours of exposure to simulated but representative Mars atmosphere, temperature, pressure and UV conditions; an unaltered photosynthetic performance demonstrated high resistance of the lichen photobiont.
SPH modelling of energy partitioning during impacts on Venus

NASA Technical Reports Server (NTRS)

Takata, T.; Ahrens, T. J.

1993-01-01

Impact cratering of the Venusian planetary surface by meteorites was investigated numerically using the Smoothed Particle Hydrodynamics (SPH) method. Venus presently has a dense atmosphere. Vigorous transfer of energy between impacting meteorites, the planetary surface, and the atmosphere is expected during impact events. The investigation concentrated on the effects of the atmosphere on energy partitioning and the flow of ejecta and gas. The SPH method is particularly suitable for studying complex motion, especially because of its ability to be extended to three dimensions. In our simulations, particles representing impactors and targets are initially set to a uniform density, and those of atmosphere are set to be in hydrostatic equilibrium. Target, impactor, and atmosphere are represented by 9800, 80, and 4200 particles, respectively. A Tillotson equation of state for granite is assumed for the target and impactor, and an ideal gas with constant specific heat ratio is used for the atmosphere. Two dimensional axisymmetric geometry was assumed and normal impacts of 10km diameter projectiles with velocities of 5, 10, 20, and 40 km/s, both with and without an atmosphere present were modeled.
Planetary Wave-Tide Interactions in Atmosphere-Ionosphere Coupling, Xiaoli Zhang, Jeffrey M. Forbes, Astrid Maute, and Maura E. Hagan

NASA Astrophysics Data System (ADS)

Zhang, X.; Forbes, J. M.; Maute, A. I.

2017-12-01

Planetary Wave-Tide Interactions in Atmosphere-Ionosphere Coupling Xiaoli Zhang, Jeffrey M. Forbes, Astrid Maute, and Maura E. Hagan The existence of secondary waves in the mesosphere and thermosphere due to nonlinear interactions between atmospheric tides and longer-period waves have been revealed in both satellite data and in the National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM). The longer-period waves include the quasi-2-day and 6-day westward-propagating "normal modes" of the atmosphere, and eastward-propagating ultra-fast Kelvin waves with periods between 2 and 4 days. The secondary waves add to both the temporal and longitude variability of the atmosphere beyond that associated with the linear superposition of the interacting waves, thus adding "complexity" to the system. Based on our knowledge of the processes governing atmosphere-ionosphere interactions, similar revelations are expected to occur in electric fields, vertical plasma drifts and F-region electron densities. Towards this end, examples of such ionospheric manifestations of wave-wave interactions in TIE-GCM simulations will be presented.
Convective Dynamics and Disequilibrium Chemistry in the Atmospheres of Giant Planets and Brown Dwarfs

NASA Astrophysics Data System (ADS)

Bordwell, Baylee; Brown, Benjamin P.; Oishi, Jeffrey S.

2018-02-01

Disequilibrium chemical processes significantly affect the spectra of substellar objects. To study these effects, dynamical disequilibrium has been parameterized using the quench and eddy diffusion approximations, but little work has been done to explore how these approximations perform under realistic planetary conditions in different dynamical regimes. As a first step toward addressing this problem, we study the localized, small-scale convective dynamics of planetary atmospheres by direct numerical simulation of fully compressible hydrodynamics with reactive tracers using the Dedalus code. Using polytropically stratified, plane-parallel atmospheres in 2D and 3D, we explore the quenching behavior of different abstract chemical species as a function of the dynamical conditions of the atmosphere as parameterized by the Rayleigh number. We find that in both 2D and 3D, chemical species quench deeper than would be predicted based on simple mixing-length arguments. Instead, it is necessary to employ length scales based on the chemical equilibrium profile of the reacting species in order to predict quench points and perform chemical kinetics modeling in 1D. Based on the results of our simulations, we provide a new length scale, derived from the chemical scale height, that can be used to perform these calculations. This length scale is simple to calculate from known chemical data and makes reasonable predictions for our dynamical simulations.
Recent Progress in Laboratory Astrophysics and Astrochemistry Achieved with the COSmIC Facility

NASA Technical Reports Server (NTRS)

Salama, Farid; Sciamma-O'Brien, Ella; Bejaoui, Salma

2017-01-01

We describe the characteristics and the capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory. COSmIC stands for "Cosmic Simulation Chamber" and is dedicated to the study of neutral and ionized molecules and nanoparticles under the low temperature and high vacuum conditions that are required to simulate various space environments such as diffuse interstellar clouds, circumstellar outflows and planetary atmospheres. COSmIC integrates a variety of state-of-the-art instruments that allow recreating simulated space conditions to generate, process and monitor cosmic analogs in the laboratory. The COSmIC experimental setup is composed of a Pulsed Discharge Nozzle (PDN) expansion, that generates a plasma in the stream of a free supersonic jet expansion, coupled to high-sensitivity, complementary in situ diagnostics: cavity ring down spectroscopy (CRDS) and laser induced fluorescence (LIF) systems for photonic detection, and Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection. Recent results obtained using COSmIC will be highlighted. In particular, the progress that has been achieved in the domain of the diffuse interstellar bands (DIBs) and in monitoring, in the laboratory, the formation of circumstellar dust grains and planetary atmosphere aerosols from their gas-phase molecular precursors. Plans for future laboratory experiments on interstellar and planetary molecules and grains will also be addressed, as well as the implications of the studies underway for astronomical observations and past and future space mission data analysis.
TOWARDS OPERATIONAL FORECASTING OF LOWER ATMOSPHERE EFFECTS ON THE UPPER ATMOSPHERE AND IONOSPHERE: INTEGRATED DYNAMICS IN EARTH’S ATMOSPHERE (IDEA)

NASA Astrophysics Data System (ADS)

Akmaev, R. A.; Fuller-Rowell, T. J.; Wu, F.; Wang, H.; Juang, H.; Moorthi, S.; Iredell, M.

2009-12-01

The upper atmosphere and ionosphere exhibit variability and phenomena that have been associated with planetary and tidal waves originating in the lower atmosphere. To study and be able to predict the effects of these global-scale dynamical perturbations on the coupled thermosphere-ionosphere-electrodynamics system a new coupled model is being developed under the IDEA project. To efficiently cross the infamous R2O “death valley”, from the outset the IDEA project leverages the natural synergy between NOAA’s National Weather Service’s (NWS) Space Weather Prediction and Environmental Modeling Centers and a NOAA-University of Colorado cooperative institute (CIRES). IDEA interactively couples a Whole Atmosphere Model (WAM) with ionosphere-plasmasphere and electrodynamics models. WAM is a 150-layer general circulation model (GCM) based on NWS’s operational weather prediction Global Forecast System (GFS) extended from its nominal top altitude of 62 km to over 600 km. It incorporates relevant physical processes including those responsible for the generation of tidal and planetary waves in the troposphere and stratosphere. Long-term simulations reveal realistic seasonal variability of tidal waves with a substantial contribution from non-migrating tidal modes, recently implicated in the observed morphology of the ionosphere. Such phenomena as the thermospheric Midnight Temperature Maximum (MTM), previously associated with the tides, are also realistically simulated for the first time.
IASB-BIRA contribution to VESPA for planetary aeronomy studies

NASA Astrophysics Data System (ADS)

Trompet, L.; Vandaele, A. C.; Geunes, Y.; Mahieux, A.; Wilquet, V.; Chamberlain, S.; Robert, S.; Thomas, I.; Erard, S.; Cecconi, B.; Le Sidaner, P.

2017-09-01

IASB-BIRA is contributing to VESPA activities by developing all necessary facilities to make accessible through the VESPA infrastructure: a) SOIR profiles of the atmosphere of Venus and b) the radiative transfer code ASIMUT for simulation or retrievals of spectra.
Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F

NASA Technical Reports Server (NTRS)

1993-01-01

The topics covered include the following: petrology, petrography, meteoritic composition, planetary geology, atmospheric composition, astronomical spectroscopy, lunar geology, Mars (planet), Mars composition, Mars surface, volcanology, Mars volcanoes, Mars craters, lunar craters, mineralogy, mineral deposits, lithology, asteroids, impact melts, planetary composition, planetary atmospheres, planetary mapping, cosmic dust, photogeology, stratigraphy, lunar craters, lunar exploration, space exploration, geochronology, tectonics, atmospheric chemistry, astronomical models, and geochemistry.
Interpretation of surface and planetary directional albedos for vegetated regions

NASA Technical Reports Server (NTRS)

Cess, Robert D.; Vulis, Inna L.

1989-01-01

An atmospheric solar radiation model has been coupled with surface reflectance measurements for two vegetation types, pasture land and savannah, in order to address several issues associated with understanding the directional planetary albedo; i.e., the dependence of planetary albedo upon solar zenith angle. These include an elucidation of processes that influence the variation of planetary albedo with solar zenith angle, as well as emphasizing potential problems associated with converting narrowband planetary albedo measurements to broadband quantities. It is suggested that, for vegetated surfaces, this latter task could be somewhat formidable, since the model simulations indicate that narrowband to broadband conversions strongly depend upon vegetation type. A further aspect of this paper is to illustrate a procedure by which reciprocity inconsistencies within a bidirectional reflectance dataset, if they are not too severe, can be circumvented.
Bacillus subtilis spore survival and expression of germination-induced bioluminescence after prolonged incubation under simulated Mars atmospheric pressure and composition: implications for planetary protection and lithopanspermia

NASA Technical Reports Server (NTRS)

Nicholson, Wayne L.; Schuerger, Andrew C.

2005-01-01

Bacterial endospores in the genus Bacillus are considered good models for studying interplanetary transfer of microbes by natural or human processes. Although spore survival during transfer itself has been the subject of considerable study, the fate of spores in extraterrestrial environments has received less attention. In this report we subjected spores of a strain of Bacillus subtilis, containing luciferase resulting from expression of an sspB-luxAB gene fusion, to simulated martian atmospheric pressure (7-18 mbar) and composition (100% CO(2)) for up to 19 days in a Mars simulation chamber. We report here that survival was similar between spores exposed to Earth conditions and spores exposed up to 19 days to simulated martian conditions. However, germination-induced bioluminescence was lower in spores exposed to simulated martian atmosphere, which suggests sublethal impairment of some endogenous spore germination processes.
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1987-01-01

Laboratory measurements were conducted to evaluate properties of atmospheric gases under simulated conditions for the outer planets. A significant addition to this effort was the capability to make such measurements at millimeter wavelengths. Measurements should soon be completed on the millimeter wave absorption from ammonia under Jovian conditions. Also studied will be the feasibility of measuring the microwave and millimeter wave properties of phosphine (PH3) under simulated Jovian conditions. Further analysis and application of the laboratory results to microwave and millimeter wave absorption data for the outer planet, such as Voyager Radio Occultation experiments, will be pursued.
Simulation of planetary entry radiative heating with a CO2 gasdynamic laser

NASA Technical Reports Server (NTRS)

Lundell, J. H.; Dickey, R. R.; Howe, J. T.

1975-01-01

Heating encountered during entry into the atmospheres of Jupiter, Saturn, and Uranus is described, followed by a discussion of the use of a CO2 gasdynamic laser to simulate the radiative component of the heating. Operation and performance of the laser is briefly described. Finally, results of laser tests of some candidate heat-shield materials are presented.
Benchmarking Geant4 for simulating galactic cosmic ray interactions within planetary bodies

DOE PAGES

Mesick, K. E.; Feldman, W. C.; Coupland, D. D. S.; ...

2018-06-20

Galactic cosmic rays undergo complex nuclear interactions with nuclei within planetary bodies that have little to no atmosphere. Radiation transport simulations are a key tool used in understanding the neutron and gamma-ray albedo coming from these interactions and tracing these signals back to geochemical composition of the target. In this paper, we study the validity of the code Geant4 for simulating such interactions by comparing simulation results to data from the Apollo 17 Lunar Neutron Probe Experiment. Different assumptions regarding the physics are explored to demonstrate how these impact the Geant4 simulation results. In general, all of the Geant4 resultsmore » over-predict the data, however, certain physics lists perform better than others. Finally, in addition, we show that results from the radiation transport code MCNP6 are similar to those obtained using Geant4.« less
Benchmarking Geant4 for simulating galactic cosmic ray interactions within planetary bodies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mesick, K. E.; Feldman, W. C.; Coupland, D. D. S.

Galactic cosmic rays undergo complex nuclear interactions with nuclei within planetary bodies that have little to no atmosphere. Radiation transport simulations are a key tool used in understanding the neutron and gamma-ray albedo coming from these interactions and tracing these signals back to geochemical composition of the target. In this paper, we study the validity of the code Geant4 for simulating such interactions by comparing simulation results to data from the Apollo 17 Lunar Neutron Probe Experiment. Different assumptions regarding the physics are explored to demonstrate how these impact the Geant4 simulation results. In general, all of the Geant4 resultsmore » over-predict the data, however, certain physics lists perform better than others. Finally, in addition, we show that results from the radiation transport code MCNP6 are similar to those obtained using Geant4.« less
Large-eddy simulations of a Salt Lake Valley cold-air pool

NASA Astrophysics Data System (ADS)

Crosman, Erik T.; Horel, John D.

2017-09-01

Persistent cold-air pools are often poorly forecast by mesoscale numerical weather prediction models, in part due to inadequate parameterization of planetary boundary-layer physics in stable atmospheric conditions, and also because of errors in the initialization and treatment of the model surface state. In this study, an improved numerical simulation of the 27-30 January 2011 cold-air pool in Utah's Great Salt Lake Basin is obtained using a large-eddy simulation with more realistic surface state characterization. Compared to a Weather Research and Forecasting model configuration run as a mesoscale model with a planetary boundary-layer scheme where turbulence is highly parameterized, the large-eddy simulation more accurately captured turbulent interactions between the stable boundary-layer and flow aloft. The simulations were also found to be sensitive to variations in the Great Salt Lake temperature and Salt Lake Valley snow cover, illustrating the importance of land surface state in modelling cold-air pools.
Effects of Bulk Composition on the Atmospheric Dynamics on Close-in Exoplanets

NASA Astrophysics Data System (ADS)

Zhang, X.; Showman, A. P.

2015-12-01

Depending on the metallicity of the protoplanetary disk, the details of gas accretion during planetary formation, and atmospheric loss during planetary evolution, the atmospheres of sub-Jupiter-sized planets could exhibit a variety of bulk compositions. Examples include hydrogen-dominated atmospheres like Jupiter, more metal-rich atmospheres like Neptune, evaporated atmospheres dominated by helium, or of course carbon dioxide, water vapor, nitrogen, and other heavy molecules as exhibited by terrestrial planets in the solar system. Here we systematically investigate the effects of atmospheric bulk compositions on temperature and wind distributions for tidally locked sub-Jupiter-sized planets using an idealized three-dimensional general circulation model (GCM). Composition—in particular, the molecular mass and specific heat—affect the sound speed, gravity wave speeds, atmospheric scale height, and Rossby deformation radius, and therefore in principle can exert significant controls on the atmospheric circulation, including the day-night temperature difference and other observables. We performed numerous simulations exploring a wide range of molecular masses and molar specific heats. The effect of molecular weight dominates. We found that a higher-molecular-weight atmosphere tends to have a larger day-night temperature contrast, a smaller eastward phase shift in the thermal light curve, and a narrower equatorial super-rotating jet that occurs in a deeper atmosphere. The zonal-mean zonal wind is smaller and more prone to exhibit a latitudinally alternating pattern in a higher-molecular-weight atmosphere. If the vertical temperature profile is close to adiabatic, molar specific heat will play a significant role in controlling the transition from a divergent flow in the upper atmosphere to a jet-dominated flow in the lower atmosphere. We are also working on analytical theories to explain aspects of the simulations relevant for possible observables on tidally locked exoplanets, such as the day-night temperature difference, thermal phase shift and root-mean-square of the wind speed. Our analytical predictions are quantitatively compared with our numerical simulations and may provide potential indicators for determining the atmospheric compositions in future observations.
AXISYMMETRIC SIMULATIONS OF HOT JUPITER–STELLAR WIND HYDRODYNAMIC INTERACTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christie, Duncan; Arras, Phil; Li, Zhi-Yun

2016-03-20

Gas giant exoplanets orbiting at close distances to the parent star are subjected to large radiation and stellar wind fluxes. In this paper, hydrodynamic simulations of the planetary upper atmosphere and its interaction with the stellar wind are carried out to understand the possible flow regimes and how they affect the Lyα transmission spectrum. Following Tremblin and Chiang, charge exchange reactions are included to explore the role of energetic atoms as compared to thermal particles. In order to understand the role of the tail as compared to the leading edge of the planetary gas, the simulations were carried out undermore » axisymmetry, and photoionization and stellar wind electron impact ionization reactions were included to limit the extent of the neutrals away from the planet. By varying the planetary gas temperature, two regimes are found. At high temperature, a supersonic planetary wind is found, which is turned around by the stellar wind and forms a tail behind the planet. At lower temperatures, the planetary wind is shut off when the stellar wind penetrates inside where the sonic point would have been. In this regime mass is lost by viscous interaction at the boundary between planetary and stellar wind gases. Absorption by cold hydrogen atoms is large near the planetary surface, and decreases away from the planet as expected. The hot hydrogen absorption is in an annulus and typically dominated by the tail, at large impact parameter, rather than by the thin leading edge of the mixing layer near the substellar point.« less
Magnetised winds and their influence in the escaping upper atmosphere of HD 209458b

NASA Astrophysics Data System (ADS)

D'Angelo, Carolina Villarreal; Esquivel, Alejandro; Schneiter, Matías; Sgró, Mario Agustín

2018-06-01

Lyman α observations during an exoplanet transit have proved to be very useful to study the interaction between the stellar wind and the planetary atmosphere. They have been extensively used to constrain planetary system parameters that are not directly observed, such as the planetary mass loss rate. In this way, Ly α observations can be a powerful tool to infer the existence of a planetary magnetic field, since it is expected that the latter will affect the escaping planetary material. To explore the effect that magnetic fields have on the Ly α absorption of HD 209458b, we run a set of 3D MHD simulations including dipolar magnetic fields for the planet and the star. We assume values for the surface magnetic field at the poles of the planet in the range of [0-5] G, and from 1 to 5 G at the poles of the star. Our models also include collisional and photo-ionisation, radiative recombination, and an approximation for the radiation pressure. Our results show that the magnetic field of the planet and the star change the shape of the Ly α absorption profile, since it controls the extent of the planetary magnetosphere and the amount of neutral material inside it. The model that best reproduces the absorption observed in HD 209458b (with canonical values for the stellar wind parameters) corresponds to a dipole planetary field of ≲ 1 gauss at the poles.

Test evaluation of potential heat shield contamination of an Outer Planet Probe's atmospheric sampling system

NASA Technical Reports Server (NTRS)

Kessler, W. C.; Woeller, F. H.; Wilkins, M. E.

1975-01-01

An Outer Planets Probe which retains the charred heatshield during atmospheric descent must deploy a sampling tube through the heatshield to extract atmospheric samples for analysis. Once the sampling tube is deployed, the atmospheric samples ingested must be free of contaminant gases generated by the heatshield. Outgassing products such as methane and water vapor are present in planetary atmospheres and hence, ingestion of such species would result in gas analyzer measurement uncertainties. This paper evaluates the potential for, and design impact of, the extracted atmospheric samples being contaminated by heatshield outgassing products. Flight trajectory data for Jupiter, Saturn and Uranus entries are analyzed to define the conditions resulting in the greatest potential for outgassing products being ingested into the probe's sampling system. An experimental program is defined and described which simulates the key flow field features for a planetary flight in a ground-based test facility. The primary parameters varied in the test include: sampling tube length, injectant mass flow rate and angle of attack. Measured contaminant levels predict the critical sampling tube length for contamination avoidance. Thus, the study demonstrates the compatibility of a retained heatshield concept and high quality atmospheric trace species measurements.
SPEX: a multi-angle Spectropolarimeter for Planetary EXploration

NASA Astrophysics Data System (ADS)

Smit, J. M.; Hasekamp, O. P.; Rietjens, J.; Stam, D.; Snik, F.; Van Harten, G.; Verlaan, A.; Voors, R.; Moon, S.; Wielinga, K.

2011-12-01

We present SPEX, the Spectropolarimeter for Planetary Exploration, which is a compact, robust and low-mass multi-viewing angle spectropolarimeter designed to operate from an orbiting satellite platform. Its purpose is to simultaneously measure, with high accuracy, the radiance and the state (degree and angle) of linear polarization of sunlight that has been scattered in a planetary atmosphere or reflected by a planetary surface. The degree of linear polarization is extremely sensitive to the microphysical properties of atmospheric or surface particles (such as size, shape, and composition), and to the vertical distribution of atmospheric particles, such as cloud top altitudes. Measurements as those performed by SPEX are therefore crucial and often the only tool for disentangling the many parameters that describe planetary atmospheres and surfaces. SPEX uses a novel, passive method for its radiance and polarization observations that is based on a carefully selected combination of polarization optics. This results in a modulation of the radiance spectrum in both amplitude and phase by the degree and angle of the linear polarization spectrum, respectively. The polarization optics consists of an achromatic quarter-wave retarder, an a-thermal multiple-order retarder, and a polarizing beam splitter. Such a configuration is implemented for a range of viewin directions, which allows sampling the full scattering phase function of each ground pixel under investigation, while orbiting the planetary body. The present design of SPEX is tuned to a Mars mission, as a payload on a satellite in a low orbit. However, the concept is perfectly applicable for Earth remote sensing from an orbiting platform like ISS or a dedicated mission, for which we are developing a breadboard. A similar concepts is under study for a mission to the Jovian system including the Galilean Moons. We will show first test results obtained with recently developed prototype of the SPEX instrument, demonstrating excellent performance and overall behavior as compared with design parameters and SPEX instrument simulator. In addition, we present results of multi-angle spectropolarimetric measurements of the Earth's atmosphere from the ground in conjunction with one of AERONET's sun photometers.
Exploring the optical contrast effect in strong atomic lines for exoplanets transiting active stars

NASA Astrophysics Data System (ADS)

Cauley, Paul W.; Redfield, Seth

2017-01-01

Transmission spectroscopy is a powerful tool for detecting and characterizing planetary atmospheres. Non-photospheric features on the stellar disk, however, can contaminate the planetary signal: during transit the observed spectrum is weighted towards the features not currently being occulted by the planet. This contrast effect can mimic absorption in the planetary atmosphere for strong atomic lines such as Na I, Ca II, and the hydrogen Balmer lines. While the contrast effect is negligible for quiet stars, contributions to the transmission signal from active stellar surfaces can produce ~1% changes in the line core. It is therefore critical that these contrast signals be differentiated from true absorption features in the planetary atmosphere. Here we present our work on simulating the contrast effect for an active stellar surface. We discuss the particular case of HD 189733 b, a well-studied hot Jupiter orbiting an active K-dwarf, due to the plethora of atomic absorption signals reported in its atmosphere.Specifically, we focus on Hα to address recent suggestions that the measured in-transit signals are a result of stellar activity. In the contrast model we include center-to-limb variations and calculate limb darkening parameters as a function of wavelength across the line of interest. The model includes contributions to the spectrum from spots, faculae and plages, filaments, and the bare stellar photosphere. Stellar rotation is also included. We find that it is very difficult to reproduce the measured in-transit Hα signals for reasonable active region parameters. In addition, it is difficult to create an in-transit contrast signature that lasts for the duration of the transit unless the planet is crossing an active latitudinal belt and is always obscuring active regions. This suggests that the Hα measurements arise predominantly in the planetary atmosphere. However, the contrast effect likely contributes to these signals. Furthermore, our results could be modified if the active regions of HD 189733 b have drastically different characteristics than solar active regions. Further observations of transits across active stars will aid in disentangling the planetary signals from the stellar.
Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

NASA Astrophysics Data System (ADS)

Way, M. J.; Aleinov, I.; Amundsen, David S.; Chandler, M. A.; Clune, T. L.; Del Genio, A. D.; Fujii, Y.; Kelley, M.; Kiang, N. Y.; Sohl, L.; Tsigaridis, K.

2017-07-01

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower to more rapid than modern Earth’s, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn’s moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future. We also discuss the current and near-future capabilities of ROCKE-3D as a community model for studying planetary and exoplanetary atmospheres.
Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

NASA Technical Reports Server (NTRS)

Way, M. J.; Aleinov, I.; Amundsen, David S.; Chandler, M. A.; Clune, T. L.; Del Genio, A.; Fujii, Y.; Kelley, M.; Kiang, N. Y.; Sohl, L.;

2017-01-01

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower to more rapid than modern Earth's, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn's moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future. We also discuss the current and near-future capabilities of ROCKE-3D as a community model for studying planetary and exoplanetary atmospheres.

Sensitivity of Tropospheric Chemical Composition to Halogen-Radical Chemistry Using a Fully Coupled Size-Resolved Multiphase Chemistry-Global Climate System: Halogen Distributions, Aerosol Composition, and Sensitivity of Climate-Relevant Gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, M.; Keene, W. C.; Easter, Richard C.

Observations and model studies suggest a significant but highly non-linear role for halogens, primarily Cl and Br, in multiphase atmospheric processes relevant to tropospheric chemistry and composition, aerosol evolution, radiative transfer, weather, and climate. The sensitivity of global atmospheric chemistry to the production of marine aerosol and the associated activation and cycling of inorganic Cl and Br was tested using a size-resolved multiphase coupled chemistry/global climate model (National Center for Atmospheric Research’s Community Atmosphere Model (CAM); v3.6.33). Simulation results showed strong meridional and vertical gradients in Cl and Br species. The simulation reproduced most available observations with reasonable confidence permittingmore » the formulation of potential mechanisms for several previously unexplained halogen phenomena including the enrichment of Br- in submicron aerosol, and the presence of a BrO maximum in the polar free troposphere. However, simulated total volatile Br mixing ratios were generally high in the troposphere. Br in the stratosphere was lower than observed due to the lack of long-lived organobromine species in the simulation. Comparing simulations using chemical mechanisms with and without reactive Cl and Br species demonstrated a significant temporal and spatial sensitivity of primary atmospheric oxidants (O3, HOx, NOx), CH4, and non-methane hydrocarbons (NMHC’s) to halogen cycling. Simulated O3 and NOx were globally lower (65% and 35%, respectively, less in the planetary boundary layer based on median values) in simulations that included halogens. Globally, little impact was seen in SO2 and non-sea-salt SO42- processing due to halogens. Significant regional differences were evident: The lifetime of nss-SO42- was extended downwind of large sources of SO2. The burden and lifetime of DMS (and its oxidation products) were lower by a factor of 5 in simulations that included halogens, versus those without, leading to a 20% reduction in nss-SO42- in the southern hemisphere planetary boundary layer based on median values.« less
Dications and thermal ions in planetary atmospheric escape

NASA Astrophysics Data System (ADS)

Lilensten, J.; Simon Wedlund, C.; Barthélémy, M.; Thissen, R.; Ehrenreich, D.; Gronoff, G.; Witasse, O.

2013-01-01

In the recent years, the presence of dications in the atmospheres of Mars, Venus, Earth and Titan has been modeled and assessed. These studies also suggested that these ions could participate to the escape of the planetary atmospheres because a large fraction of them is unstable and highly energetic. When they dissociate, their internal energy is transformed into kinetic energy which may be larger than the escape energy. The goal of this study is to assess the impact of the doubly-charged ions in the escape of CO2-dominated planetary atmospheres and to compare it to the escape of thermal photo-ions. We solve a Boltzmann transport equation at daytime taking into account the dissociative states of CO2++ for a simplified single constituent atmosphere of a case-study planet. We compute the escape of fast ions using a Beer-Lambert approach. We study three test-cases. On a Mars-analog planet in today's conditions, we retrieve the measured electron escape flux. When comparing the two mechanisms (i.e. excluding solar wind effects, sputtering, etc.), the escape due to the fast ions issuing from the dissociation of dications may account for up to 6% of the total and the escape of thermal ions for the remaining. We show that these two mechanisms cannot explain the escape of the atmosphere since the magnetic field vanished and even contribute only marginally to this loss. We show that with these two mechanisms, the atmosphere of a Mars analog planet would empty in another giga years and a half. At Venus orbit, the contribution of the dications in the escape rate is negligible. When simulating the hot Jupiter HD 209458 b, the two processes cannot explain the measured escape flux of C+. This study shows that the dications may constitute a source of the escape of planetary atmospheres which had not been taken into account until now. This source, although marginal, is not negligible. The influence of the photoionization is of course large, but cannot explain alone the loss of Mars' atmosphere nor the atmospheric escape of HD 209458 b.
Convective dynamics and chemical disequilibrium in the atmospheres of substellar objects

NASA Astrophysics Data System (ADS)

Bordwell, Baylee; Brown, Benjamin P.; Oishi, Jeffrey S.

2017-11-01

The thousands of substellar objects now known provide a unique opportunity to test our understanding of atmospheric dynamics across a range of environments. The chemical timescales of certain species transition from being much shorter than the dynamical timescales to being much longer than them at a point in the atmosphere known as the quench point. This transition leads to a state of dynamical disequilibrium, the effects of which can be used to probe the atmospheric dynamics of these objects. Unfortunately, due to computational constraints, models that inform the interpretation of these observations are run at dynamical parameters which are far from realistic values. In this study, we explore the behavior of a disequilibrium chemical process with increasingly realistic planetary conditions, to quantify the effects of the approximations used in current models. We simulate convection in 2-D, plane-parallel, polytropically-stratified atmospheres, into which we add reactive passive tracers that explore disequilibrium behavior. We find that as we increase the Rayleigh number, and thus achieve more realistic planetary conditions, the behavior of these tracers does not conform to the classical predictions of disequilibrium chemistry.
Atmosphere Expansion and Mass Loss of Close-orbit Giant Exoplanets Heated by Stellar XUV. I. Modeling of Hydrodynamic Escape of Upper Atmospheric Material

NASA Astrophysics Data System (ADS)

Shaikhislamov, I. F.; Khodachenko, M. L.; Sasunov, Yu. L.; Lammer, H.; Kislyakova, K. G.; Erkaev, N. V.

2014-11-01

In the present series of papers we propose a consistent description of the mass loss process. To study in a comprehensive way the effects of the intrinsic magnetic field of a close-orbit giant exoplanet (a so-called hot Jupiter) on atmospheric material escape and the formation of a planetary inner magnetosphere, we start with a hydrodynamic model of an upper atmosphere expansion in this paper. While considering a simple hydrogen atmosphere model, we focus on the self-consistent inclusion of the effects of radiative heating and ionization of the atmospheric gas with its consequent expansion in the outer space. Primary attention is paid to an investigation of the role of the specific conditions at the inner and outer boundaries of the simulation domain, under which different regimes of material escape (free and restricted flow) are formed. A comparative study is performed of different processes, such as X-ray and ultraviolet (XUV) heating, material ionization and recombination, H_3^ + cooling, adiabatic and Lyα cooling, and Lyα reabsorption. We confirm the basic consistency of the outcomes of our modeling with the results of other hydrodynamic models of expanding planetary atmospheres. In particular, we determine that, under the typical conditions of an orbital distance of 0.05 AU around a Sun-type star, a hot Jupiter plasma envelope may reach maximum temperatures up to ~9000 K with a hydrodynamic escape speed of ~9 km s-1, resulting in mass loss rates of ~(4-7) · 1010 g s-1. In the range of the considered stellar-planetary parameters and XUV fluxes, that is close to the mass loss in the energy-limited case. The inclusion of planetary intrinsic magnetic fields in the model is a subject of the follow-up paper (Paper II).
The Habitability of Proxima Centauri b: Environmental States and Observational Discriminants.

PubMed

Meadows, Victoria S; Arney, Giada N; Schwieterman, Edward W; Lustig-Yaeger, Jacob; Lincowski, Andrew P; Robinson, Tyler; Domagal-Goldman, Shawn D; Deitrick, Russell; Barnes, Rory K; Fleming, David P; Luger, Rodrigo; Driscoll, Peter E; Quinn, Thomas R; Crisp, David

2018-02-01

Proxima Centauri b provides an unprecedented opportunity to understand the evolution and nature of terrestrial planets orbiting M dwarfs. Although Proxima Cen b orbits within its star's habitable zone, multiple plausible evolutionary paths could have generated different environments that may or may not be habitable. Here, we use 1-D coupled climate-photochemical models to generate self-consistent atmospheres for several evolutionary scenarios, including high-O 2 , high-CO 2 , and more Earth-like atmospheres, with both oxic and anoxic compositions. We show that these modeled environments can be habitable or uninhabitable at Proxima Cen b's position in the habitable zone. We use radiative transfer models to generate synthetic spectra and thermal phase curves for these simulated environments, and use instrument models to explore our ability to discriminate between possible planetary states. These results are applicable not only to Proxima Cen b but to other terrestrial planets orbiting M dwarfs. Thermal phase curves may provide the first constraint on the existence of an atmosphere. We find that James Webb Space Telescope (JWST) observations longward of 10 μm could characterize atmospheric heat transport and molecular composition. Detection of ocean glint is unlikely with JWST but may be within the reach of larger-aperture telescopes. Direct imaging spectra may detect O 4 absorption, which is diagnostic of massive water loss and O 2 retention, rather than a photosynthetic biosphere. Similarly, strong CO 2 and CO bands at wavelengths shortward of 2.5 μm would indicate a CO 2 -dominated atmosphere. If the planet is habitable and volatile-rich, direct imaging will be the best means of detecting habitability. Earth-like planets with microbial biospheres may be identified by the presence of CH 4 -which has a longer atmospheric lifetime under Proxima Centauri's incident UV-and either photosynthetically produced O 2 or a hydrocarbon haze layer. Key Words: Planetary habitability and biosignatures-Planetary atmospheres-Exoplanets-Spectroscopic biosignatures-Planetary science-Proxima Centauri b. Astrobiology 18, 133-189.
A conceptual framework for using Doppler radar acquired atmospheric data for flight simulation

NASA Technical Reports Server (NTRS)

Campbell, W.

1983-01-01

A concept is presented which can permit turbulence simulation in the vicinity of microbursts. The method involves a large data base, but should be fast enough for use with flight simulators. The model permits any pilot to simulate any flight maneuver in any aircraft. The model simulates a wind field with three-component mean winds and three-component turbulent gusts, and gust variation over the body of an aircraft so that all aerodynamic loads and moments can be calculated. The time and space variation of mean winds and turbulent intensities associated with a particular atmospheric phenomenon such as a microburst is used in the model. In fact, Doppler radar data such as provided by JAWS is uniquely suited for use with the proposed model. The concept is completely general and is not restricted to microburst studies. Reentry and flight in terrestrial or planetary atmospheres could be realistically simulated if supporting data of sufficient resolution were available.
Simulation of large scale motions and small scale structures in planetary atmospheres and oceans: From laboratory to space experiments on ISS

NASA Astrophysics Data System (ADS)

Egbers, Christoph; Futterer, Birgit; Zaussinger, Florian; Harlander, Uwe

2014-05-01

Baroclinic waves are responsible for the transport of heat and momentum in the oceans, in the Earth's atmosphere as well as in other planetary atmospheres. The talk will give an overview on possibilities to simulate such large scale as well as co-existing small scale structures with the help of well defined laboratory experiments like the baroclinic wave tank (annulus experiment). The analogy between the Earth's atmosphere and the rotating cylindrical annulus experiment only driven by rotation and differential heating between polar and equatorial regions is obvious. From the Gulf stream single vortices seperate from time to time. The same dynamics and the co-existence of small and large scale structures and their separation can be also observed in laboratory experiments as in the rotating cylindrical annulus experiment. This experiment represents the mid latitude dynamics quite well and is part as a central reference experiment in the German-wide DFG priority research programme ("METSTRÖM", SPP 1276) yielding as a benchmark for lot of different numerical methods. On the other hand, those laboratory experiments in cylindrical geometry are limited due to the fact, that the surface and real interaction between polar and equatorial region and their different dynamics can not be really studied. Therefore, I demonstrate how to use the very successful Geoflow I and Geoflow II space experiment hardware on ISS with future modifications for simulations of small and large scale planetary atmospheric motion in spherical geometry with differential heating between inner and outer spheres as well as between the polar and equatorial regions. References: Harlander, U., Wenzel, J., Wang, Y., Alexandrov, K. & Egbers, Ch., 2012, Simultaneous PIV- and thermography measurements of partially blocked flow in a heated rotating annulus, Exp. in Fluids, 52 (4), 1077-1087 Futterer, B., Krebs, A., Plesa, A.-C., Zaussinger, F., Hollerbach, R., Breuer, D. & Egbers, Ch., 2013, Sheet-like and plume-like thermal flow in a spherical convection experiment performed under microgravity, J. Fluid Mech., vol. 75, p 647-683
The influence of Mars' magnetic topology on atmospheric escape

NASA Astrophysics Data System (ADS)

Curry, S.; Luhmann, J. G.; DiBraccio, G. A.; Dong, C.; Xu, S.; Mitchell, D.; Gruesbeck, J.; Espley, J. R.; Connerney, J. E. P.; McFadden, J. P.; Ma, Y. J.; Brain, D.

2017-12-01

At weakly magnetized planets such as Mars and Venus, the solar wind directly interacts with the upper atmosphere where ions can be picked up and swept away by the background convection electric field. These pick-up ions have a gyroradius on the planetary scale that is largely dominated by the interplanetary magnetic field (IMF). But at Mars, their trajectory is also influenced by the existence of remanent crustal magnetic fields, which are thought to create a shielding effect for escaping planetary ions when they are on the dayside. Consequently, the magnetic topology changes at Mars as magnetic reconnection occurs between the draped (IMF) and the crustal magnetic fields (closed). The resulting topology includes open field lines in the solar wind with one footprint attached to the planet. Using magnetohydrodynamic (MHD) and test particle simulations, we will explore the influence of the magnetic topology on ion escape. We will present escape rates for planetary ions for different crustal field positions during different IMF configurations, with +/-BY and +/-BZ components in the Mars Sun Orbit (MSO) coordinate system. We will also compare global maps of ion outflow and escape with open / closed magnetic field line maps and compare our results with ion fluxes and magnetic field data from the Mars Atmospheric and Volatile EvolutioN (MAVEN) mission. Our results relating the dynamic magnetic field topology at Mars and planetary ion escape are an important aspect of magnetospheric physics and planetary evolution, both of which have applications to our own solar system and the increasing number of exoplanets discovered every year.
Studies of Tenuous Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Combi, Michael R.

1998-01-01

The final report includes an overall project overview as well as scientific background summaries of dust and sodium in comets, and tenuous atmospheres of Jupiter's natural satellites. Progress and continuing work related to dust coma and tenuous atmospheric studies are presented. Also included are published articles written during the course of the report period. These are entitled: (1) On Europa's Magnetospheric Interaction: An MHD Simulation; (2) Dust-Gas Interrelations in Comets: Observations and Theory; and (3) Io's Plasma Environment During the Galileo Flyby: Global Three Dimensional MHD Modeling with Adaptive Mesh Refinement.
The applications of chemical thermodynamics and chemical kinetics to planetary atmospheres research

NASA Technical Reports Server (NTRS)

Fegley, Bruce, Jr.

1990-01-01

A review of the applications of chemical thermodynamics and chemical kinetics to planetary atmospheres research during the past four decades is presented with an emphasis on chemical equilibrium models and thermochemical kinetics. Several current problems in planetary atmospheres research such as the origin of the atmospheres of the terrestrial planets, atmosphere-surface interactions on Venus and Mars, deep mixing in the atmospheres of the gas giant planets, and the origin of the atmospheres of outer planet satellites all require laboratory data on the kinetics of thermochemical reactions for their solution.
Dynamical Coupling Between the Stratosphere and the Troposphere: The Influence of External Forcings

NASA Astrophysics Data System (ADS)

Hansen, Felicitas; Matthes, Katja

2013-04-01

The dynamical coupling between the stratosphere and the troposphere is dominated by planetary waves that are generated in the troposphere by orography and land-sea contrasts. These waves travel upward into the stratosphere where they either dissipate or are reflected downward to impact the troposphere again. Through the interaction with the zonal mean flow planetary waves can induce stratospheric sudden warmings (SSWs), i.e., conditions during NH winter where the stratospheric polar vortex is disturbed so that the zonal mean zonal wind in the NH stratospheric jet becomes easterly and the polar cap meridional temperature gradient reverses. Since strong major SSWs can propagate down into the troposphere and even affect surface weather, SSWs present a strong and clear manifestation of the dynamical coupling in the stratosphere-troposphere system. We will investigate the influence of some external forcings, namely sea surface temperatures (SSTs), anthropogenic greenhouse gases and the quasi-biennial oscillation (QBO), on these coupling processes. Thereby we are interested in how the distribution of SSWs in the winter months changes due to the different forcings, whether the events evolve differently, and whether they show differences in their preconditioning, e.g. a different wave geometry. We will also investigate whether and how vertical reflective surfaces in the stratosphere, which can reflect upward propagating planetary waves, influence the evolution of SSWs. To address these questions, we performed a set of model simulations with NCAR's Community Earth System Model (CESM), a coupled model system including an interactive ocean (POP2), land (CLM4), sea ice (CICE) and atmosphere (NCAR's Whole Atmosphere Community Climate Model (WACCM)) component. Our control experiment is a 140-year simulation with the fully coupled atmosphere-ocean version of CESM. A second experiment is a 55-year simulation with only CESM's atmospheric component WACCM, a fully interactive chemistry-climate model extending from the Earth's surface through the thermosphere (about 140 km), with underlying climatological SSTs obtained from the coupled CESM control run. A third 55-year simulation is performed without the nudging of the equatorial QBO. All three simulations develop under conditions where greenhouse gases are held constant at the 1960 level. In a fourth simulations, the greenhouse gases follow the RCP8.5 scenario. From the differences of the individual simulations to the control experiment we can estimate the respective roles of SSTs, the QBO and anthropogenic greenhouse gases for the stratosphere-troposphere coupling. The model results will be compared to the Modern Era Retrospective-Analysis for Research and Applications (MERRA) dataset.
Laboratory Simulations of Martian and Venusian Aeolian Processes

NASA Technical Reports Server (NTRS)

Greeley, Ronald

1999-01-01

With the flyby of the Neptune system by Voyager, the preliminary exploration of the Solar System was accomplished. Data have been returned for all major planets and satellites except the Pluto system. Results show that the surfaces of terrestrial planets and satellites have been subjected to a wide variety of geological processes. On solid- surface planetary objects having an atmosphere, aeolian processes are important in modifying their surfaces through the redistribution of fine-grained material by the wind. Bedrock may be eroded to produce particles and the particles transported by wind for deposition in other areas. This process operates on Earth today and is evident throughout the geological record. Aeolian processes also occur on Mars, Venus, and possibly Titan and Triton, both of which are outer planet satellites that have atmospheres. Mariner 9 and Viking results show abundant wind-related landforms on Mars, including dune fields and yardangs (wind-eroded hills). On Venus, measurements made by the Soviet Venera and Vega spacecraft and extrapolations from the Pioneer Venus atmospheric probes show that surface winds are capable of transporting particulate materials and suggest that aeolian processes may operate on that planet as well. Magellan radar images of Venus show abundant wind streaks in some areas, as well as dune fields and a zone of possible yardangs. The study of planetary aeolian processes must take into account diverse environments, from the cold, low-density atmosphere of Mars to the extremely hot, high- density Venusian atmosphere. Factors such as threshold wind speeds (minimum wind velocity needed to move particles), rates of erosion and deposition, trajectories of windblown particles, and aeolian flow fields over various landforms are all important aspects of the problem. In addition, study of aeolian terrains on Earth using data analogous to planetary data-collection systems is critical to the interpretation of spacecraft information and places constraints on results from numerical models and laboratory simulations.
A Massively Parallel Hybrid Dusty-Gasdynamics and Kinetic Direct Simulation Monte Carlo Model for Planetary Applications

NASA Technical Reports Server (NTRS)

Combi, Michael R.

2004-01-01

In order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic (MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important. At the University of Michigan we have an established base of experience and expertise in numerical simulations based on particle codes which address these physical regimes. The Principal Investigator, Dr. Michael Combi, has over 20 years of experience in the development of particle-kinetic and hybrid kinetichydrodynamics models and their direct use in data analysis. He has also worked in ground-based and space-based remote observational work and on spacecraft instrument teams. His research has involved studies of cometary atmospheres and ionospheres and their interaction with the solar wind, the neutral gas clouds escaping from Jupiter s moon Io, the interaction of the atmospheres/ionospheres of Io and Europa with Jupiter s corotating magnetosphere, as well as Earth s ionosphere. This report describes our progress during the year. The contained in section 2 of this report will serve as the basis of a paper describing the method and its application to the cometary coma that will be continued under a research and analysis grant that supports various applications of theoretical comet models to understanding the inner comae of comets (grant NAGS- 13239 from the Planetary Atmospheres program).
Johnson Space Center's Regenerative Life Support Systems Test Bed

NASA Technical Reports Server (NTRS)

Barta, D. J.; Henninger, D. L.

1996-01-01

The Regenerative Life Support Systems (RLSS) Test Bed at NASA's Johnson Space Center is an atmospherically closed, controlled environment facility for human testing of regenerative life support systems using higher plants in conjunction with physicochemical life support systems. The facility supports NASA's Advanced Life Support (ALS) Program. The facility is comprised of two large scale plant growth chambers, each with approximately 11 m2 growing area. The root zone in each chamber is configurable for hydroponic or solid media plant culture systems. One of the two chambers, the Variable Pressure Growth Chamber (VPGC), is capable of operating at lower atmospheric pressures to evaluate a range of environments that may be used in a planetary surface habitat; the other chamber, the Ambient Pressure Growth Chamber (APGC) operates at ambient atmospheric pressure. The air lock of the VPGC is currently being outfitted for short duration (1 to 15 day) human habitation at ambient pressures. Testing with and without human subjects will focus on 1) integration of biological and physicochemical air and water revitalization systems; 2) effect of atmospheric pressure on system performance; 3) planetary resource utilization for ALS systems, in which solid substrates (simulated planetary soils or manufactured soils) are used in selected crop growth studies; 4) environmental microbiology and toxicology; 5) monitoring and control strategies; and 6) plant growth systems design. Included are descriptions of the overall design of the test facility, including discussions of the atmospheric conditioning, thermal control, lighting, and nutrient delivery systems.
Johnson Space Center's Regenerative Life Support Systems Test Bed

NASA Astrophysics Data System (ADS)

Barta, D. J.; Henninger, D. L.

1996-01-01

The Regenerative Life Support Systems (RLSS) Test Bed at NASA's Johnson Space Center is an atmospherically closed, controlled environment facility for human testing of regenerative life support systems using higher plants in conjunction with physicochemical life support systems. The facility supports NASA's Advanced Life Support (ALS) Program. The facility is comprised of two large scale plant growth chambers, each with approximately 11 m^2 growing area. The root zone in each chamber is configurable for hydroponic or solid media plant culture systems. One of the two chambers, the Variable Pressure Growth Chamber (VPGC), is capable of operating at lower atmospheric pressures to evaluate a range of environments that may be used in a planetary surface habitat; the other chamber, the Ambient Pressure Growth Chamber (APGC) operates at ambient atmospheric pressure. The air lock of the VPGC is currently being outfitted for short duration (1 to 15 day) human habitation at ambient pressures. Testing with and without human subjects will focus on 1) integration of biological and physicochemical air and water revitalization systems; 2) effect of atmospheric pressure on system performance; 3) planetary resource utilization for ALS systems, in which solid substrates (simulated planetary soils or manufactured soils) are used in selected crop growth studies; 4) environmental microbiology and toxicology; 5) monitoring and control strategies; and 6) plant growth systems design. Included are descriptions of the overall design of the test facility, including discussions of the atmospheric conditioning, thermal control, lighting, and nutrient delivery systems.

The Habitability of Proxima Centauri b: Environmental States and Observational Discriminants

PubMed Central

Arney, Giada N.; Schwieterman, Edward W.; Lustig-Yaeger, Jacob; Lincowski, Andrew P.; Robinson, Tyler; Domagal-Goldman, Shawn D.; Deitrick, Russell; Barnes, Rory K.; Fleming, David P.; Luger, Rodrigo; Driscoll, Peter E.; Quinn, Thomas R.; Crisp, David

2018-01-01

Abstract Proxima Centauri b provides an unprecedented opportunity to understand the evolution and nature of terrestrial planets orbiting M dwarfs. Although Proxima Cen b orbits within its star's habitable zone, multiple plausible evolutionary paths could have generated different environments that may or may not be habitable. Here, we use 1-D coupled climate-photochemical models to generate self-consistent atmospheres for several evolutionary scenarios, including high-O2, high-CO2, and more Earth-like atmospheres, with both oxic and anoxic compositions. We show that these modeled environments can be habitable or uninhabitable at Proxima Cen b's position in the habitable zone. We use radiative transfer models to generate synthetic spectra and thermal phase curves for these simulated environments, and use instrument models to explore our ability to discriminate between possible planetary states. These results are applicable not only to Proxima Cen b but to other terrestrial planets orbiting M dwarfs. Thermal phase curves may provide the first constraint on the existence of an atmosphere. We find that James Webb Space Telescope (JWST) observations longward of 10 μm could characterize atmospheric heat transport and molecular composition. Detection of ocean glint is unlikely with JWST but may be within the reach of larger-aperture telescopes. Direct imaging spectra may detect O4 absorption, which is diagnostic of massive water loss and O2 retention, rather than a photosynthetic biosphere. Similarly, strong CO2 and CO bands at wavelengths shortward of 2.5 μm would indicate a CO2-dominated atmosphere. If the planet is habitable and volatile-rich, direct imaging will be the best means of detecting habitability. Earth-like planets with microbial biospheres may be identified by the presence of CH4—which has a longer atmospheric lifetime under Proxima Centauri's incident UV—and either photosynthetically produced O2 or a hydrocarbon haze layer. Key Words: Planetary habitability and biosignatures—Planetary atmospheres—Exoplanets—Spectroscopic biosignatures—Planetary science—Proxima Centauri b. Astrobiology 18, 133–189. PMID:29431479
PLANETARY EMBRYO BOW SHOCKS AS A MECHANISM FOR CHONDRULE FORMATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mann, Christopher R.; Boley, Aaron C.; Morris, Melissa A.

2016-02-20

We use radiation hydrodynamics with direct particle integration to explore the feasibility of chondrule formation in planetary embryo bow shocks. The calculations presented here are used to explore the consequences of a Mars-size planetary embryo traveling on a moderately excited orbit through the dusty, early environment of the solar system. The embryo’s eccentric orbit produces a range of supersonic relative velocities between the embryo and the circularly orbiting gas and dust, prompting the formation of bow shocks. Temporary atmospheres around these embryos, which can be created via volatile outgassing and gas capture from the surrounding nebula, can non-trivially affect thermalmore » profiles of solids entering the shock. We explore the thermal environment of solids that traverse the bow shock at different impact radii, the effects that planetoid atmospheres have on shock morphologies, and the stripping efficiency of planetoidal atmospheres in the presence of high relative winds. Simulations are run using adiabatic and radiative conditions, with multiple treatments for the local opacities. Shock speeds of 5, 6, and 7 km s{sup −1} are explored. We find that a high-mass atmosphere and inefficient radiative conditions can produce peak temperatures and cooling rates that are consistent with the constraints set by chondrule furnace studies. For most conditions, the derived cooling rates are potentially too high to be consistent with chondrule formation.« less
Past and future of radio occultation studies of planetary atmospheres

NASA Technical Reports Server (NTRS)

Eshleman, Von R.; Hinson, David P.; Tyler, G. Leonard; Lindal, Gunnar F.

1987-01-01

Measurements of radio waves that have propagated through planetary atmospheres have provided exploratory results on atmospheric constituents, structure, dynamics, and ionization for Venus, Mars, Titan, Jupiter, Saturn, and Uranus. Highlights of past results are reviewed in order to define and illustrate the potential of occultation and related radio studies in future planetary missions.
Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Way, M. J.; Aleinov, I.; Amundsen, David S.

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower tomore » more rapid than modern Earth’s, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn’s moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future. We also discuss the current and near-future capabilities of ROCKE-3D as a community model for studying planetary and exoplanetary atmospheres.« less
STRONG DEPENDENCE OF THE INNER EDGE OF THE HABITABLE ZONE ON PLANETARY ROTATION RATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Jun; Abbot, Dorian S.; Boué, Gwenaël

2014-05-20

Planetary rotation rate is a key parameter in determining atmospheric circulation and hence the spatial pattern of clouds. Since clouds can exert a dominant control on planetary radiation balance, rotation rate could be critical for determining the mean planetary climate. Here we investigate this idea using a three-dimensional general circulation model with a sophisticated cloud scheme. We find that slowly rotating planets (like Venus) can maintain an Earth-like climate at nearly twice the stellar flux as rapidly rotating planets (like Earth). This suggests that many exoplanets previously believed to be too hot may actually be habitable, depending on their rotationmore » rate. The explanation for this behavior is that slowly rotating planets have a weak Coriolis force and long daytime illumination, which promotes strong convergence and convection in the substellar region. This produces a large area of optically thick clouds, which greatly increases the planetary albedo. In contrast, on rapidly rotating planets a much narrower belt of clouds form in the deep tropics, leading to a relatively low albedo. A particularly striking example of the importance of rotation rate suggested by our simulations is that a planet with modern Earth's atmosphere, in Venus' orbit, and with modern Venus' (slow) rotation rate would be habitable. This would imply that if Venus went through a runaway greenhouse, it had a higher rotation rate at that time.« less
Atmospheric microphysical experiments on an orbital platform

NASA Technical Reports Server (NTRS)

Eaton, L. R.

1974-01-01

The Zero-Gravity Atmospheric Cloud Physics Laboratory is a Shuttle/Spacelab payload which will be capable of performing a large range of microphysics experiments. This facility will complement terrestrial cloud physics research by allowing many experiments to be performed which cannot be accomplished within the confines of a terrestrial laboratory. This paper reviews the general Cloud Physics Laboratory concept and the experiment scope. The experimental constraints are given along with details of the proposed equipment. Examples of appropriate experiments range from three-dimensional simulation of the earth and planetary atmosphere and of ocean circulation to cloud electrification processes and the effects of atmospheric pollution materials on microphysical processes.
A comparative study of the mechanisms of migrating diurnal tidal variability due to interaction with propagating planetary waves

NASA Astrophysics Data System (ADS)

Chang, Loren; Palo, Scott; Liu, Hanli

The migrating diurnal tide is one of the dominant dynamical features of the Earth's Mesosphere and Lower Thermosphere (MLT) region, particularly at low latitudes. As an actively forced disturbance with a period of 24 hours and westward zonal wave number 1, the migrating diurnal tide represents the atmospheric response to the largest component of solar forcing, propagating upwards from excitation regions in the lower atmosphere. While the seasonal evolution of the migrating diurnal tide has been well explored, ground-based observations of the tide have exhibited a modulation of tidal amplitudes at periods related to those of propagating planetary waves generally present in the region, as well as a decrease in tidal amplitudes during large planetary wave events. Past studies have attributed tidal amplitude modulation to the presence of child waves generated as a byproduct of nonlinear wave-tide interactions. The resulting child waves have frequencies and wavenumbers that are the sum and difference of those of the parent waves. Many questions still remain about the nature and physical drivers responsible for such interactions. The conditions under which various planetary waves may or may not interact with the atmospheric tides, the overall effect on the tidal response, as well as the physical mechanisms coupling the planetary wave and the tide interaction, which has not clearly been determined. These questions are addressed in a recent modeling study, by examining two general categories of planetary waves that are known to attain significant amplitudes in the low latitude and equa-torial region where the migrating diurnal tide is dominant. These are the eastward propagating class of ultra fast Kelvin (UFK) waves with periods near three days which attain their largest amplitudes in the temperature and zonal wind fields of the equatorial lower thermosphere. The second wave examined is the quasi-two day wave (QTDW) which is a westward propagating Rossby wave and can amplify raplidly due to a nonlinear interaction with the mean flow and attain large amplitudes in both components of the wind field and the temperature field in the summer hemisphere over a period of a few days during post-solstice periods. The NCAR Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM) and Whole Atmosphere Community Climate Model (WACCM) are both state of the art general circulation models and are utilized to simulate the aforementioned planetary waves. The goal of this study is to identify specific changes in the structure of the migrat-ing diurnal tide due to interaction with these planetary waves and to understand the driving processes. The physical mechanisms that serve to couple the tide and the planetary waves are identified through analysis of the tidal momentum tendencies, the background atmosphere, as well as changes in tidal propagation. Results showing the impact of these planetary waves on the structure and evolution of the migrating diurnal tide will be presented.
High Temperature, Controlled-Atmosphere Aerodynamic Levitation Experiments with Applications in Planetary Science

NASA Astrophysics Data System (ADS)

Macris, C. A.; Badro, J.; Eiler, J. M.; Stolper, E. M.

2016-12-01

The aerodynamic levitation laser apparatus is an instrument in which spherical samples are freely floated on top of a stream of gas while being heated with a CO2laser to temperatures up to about 3500 °C. Laser heated samples, ranging in size from 0.5 to 3.5 mm diameter, can be levitated in a variety of chemically active or inert atmospheres in a gas-mixing chamber (e.g., Hennet et al. 2006; Pack et al. 2010). This allows for containerless, controlled-atmosphere, high temperature experiments with potential for applications in earth and planetary science. A relatively new technique, aerodynamic levitation has been used mostly for studies of the physical properties of liquids at high temperatures (Kohara et al. 2011), crystallization behavior of silicates and oxides (Arai et al. 2004), and to prepare glasses from compositions known to crystallize upon quenching (Tangeman et al. 2001). More recently, however, aerodynamic levitation with laser heating has been used as an experimental technique to simulate planetary processes. Pack et al. (2010) used levitation and melting experiments to simulate chondrule formation by using Ar-H2 as the flow gas, thus imposing a reducing atmosphere, resulting in reduction of FeO, Fe2O3, and NiO to metal alloys. Macris et al. (2015) used laser heating with aerodynamic levitation to reproduce the textures and diffusion profiles of major and minor elements observed in impact ejecta from the Australasian strewn field, by melting a powdered natural tektite mixed with 60-100 μm quartz grains on a flow of pure Ar gas. These experiments resulted in quantitative modeling of Si and Al diffusion, which allowed for interpretations regarding the thermal histories of natural tektites and their interactions with the surrounding impact vapor plume. Future experiments will employ gas mixing (CO, CO2, H2, O, Ar) in a controlled atmosphere levitation chamber to explore the range of fO2applicable to melt-forming impacts on other rocky planetary bodies, including the Moon and Mars. Arai et al., Rev. Sci. Instrum. 75, 2262-2265 (2004) Hennet et al., Rev. Sci. Instrum. 73, 124-129 (2001) Kohara et al., P. Natl. Acad. Sci.USA 108, 14780-14785 (2011) Macris et al., GSA Abstracts with Programs 47, 437 (2015) Pack et al., Geochem. T. 11, 1-16 (2010) Tangeman et al., Geophys. Res. Lett. 28, 2517-2520 (2001)
Pre-conditioned backward Monte Carlo solutions to radiative transport in planetary atmospheres. Fundamentals: Sampling of propagation directions in polarising media

NASA Astrophysics Data System (ADS)

García Muñoz, A.; Mills, F. P.

2015-01-01

Context. The interpretation of polarised radiation emerging from a planetary atmosphere must rely on solutions to the vector radiative transport equation (VRTE). Monte Carlo integration of the VRTE is a valuable approach for its flexible treatment of complex viewing and/or illumination geometries, and it can intuitively incorporate elaborate physics. Aims: We present a novel pre-conditioned backward Monte Carlo (PBMC) algorithm for solving the VRTE and apply it to planetary atmospheres irradiated from above. As classical BMC methods, our PBMC algorithm builds the solution by simulating the photon trajectories from the detector towards the radiation source, i.e. in the reverse order of the actual photon displacements. Methods: We show that the neglect of polarisation in the sampling of photon propagation directions in classical BMC algorithms leads to unstable and biased solutions for conservative, optically-thick, strongly polarising media such as Rayleigh atmospheres. The numerical difficulty is avoided by pre-conditioning the scattering matrix with information from the scattering matrices of prior (in the BMC integration order) photon collisions. Pre-conditioning introduces a sense of history in the photon polarisation states through the simulated trajectories. Results: The PBMC algorithm is robust, and its accuracy is extensively demonstrated via comparisons with examples drawn from the literature for scattering in diverse media. Since the convergence rate for MC integration is independent of the integral's dimension, the scheme is a valuable option for estimating the disk-integrated signal of stellar radiation reflected from planets. Such a tool is relevant in the prospective investigation of exoplanetary phase curves. We lay out two frameworks for disk integration and, as an application, explore the impact of atmospheric stratification on planetary phase curves for large star-planet-observer phase angles. By construction, backward integration provides a better control than forward integration over the planet region contributing to the solution, and this presents a clear advantage when estimating the disk-integrated signal at moderate and large phase angles. A one-slab, plane-parallel version of the PBMC algorithm is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/573/A72
Impact erosion of terrestrial planetary atmospheres

NASA Technical Reports Server (NTRS)

Ahrens, Thomas J.

1992-01-01

I review current ideas about the nature of the planetesimals - composition, size distribution, and the planetary encounter velocity. Previous papers on accretion and erosion of planetary atmospheres as a result of multiple impacts are reviewed. Finally, the effects of blowing off a substantial fraction of the atmosphere from a terrestrial planet due to a single giant body impact are discussed.
Impact erosion of terrestrial planetary atmospheres

NASA Technical Reports Server (NTRS)

Ahrens, Thomas J.

1993-01-01

I review current ideas about the nature of the planetesimals - composition, size distribution, and the planetary encounter velocity. Previous papers on accretion and erosion of planetary atmospheres as a result of multiple impacts are reviewed. Finally, the effects of blowing off a substantial fraction of the atmosphere from a terrestrial planet due to a single giant body impact are discussed.
Analytic theory of orbit contraction and ballistic entry into planetary atmospheres

NASA Technical Reports Server (NTRS)

Longuski, J. M.; Vinh, N. X.

1980-01-01

A space object traveling through an atmosphere is governed by two forces: aerodynamic and gravitational. On this premise, equations of motion are derived to provide a set of universal entry equations applicable to all regimes of atmospheric flight from orbital motion under the dissipate force of drag through the dynamic phase of reentry, and finally to the point of contact with the planetary surface. Rigorous mathematical techniques such as averaging, Poincare's method of small parameters, and Lagrange's expansion, applied to obtain a highly accurate, purely analytic theory for orbit contraction and ballistic entry into planetary atmospheres. The theory has a wide range of applications to modern problems including orbit decay of artificial satellites, atmospheric capture of planetary probes, atmospheric grazing, and ballistic reentry of manned and unmanned space vehicles.
The rigid shell component for superrotation in planetary atmospheres: Angular momentum budget, mechanical analog and simulation of the spin up process

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Harris, I.

1981-01-01

An analysis of superrotation in the atmosphere of planets, with rotation axis perpendicular to the orbital plane is presented. As the atmosphere expands, Hadley cells develop producing a redistribution of mass and angular momentum. A three dimensional thermally driven zonally symmetric spectral model and Laplace transformation simulate the time evolution of a fluid leading from corotation under globally uniform heating to superrotation under globally nonuniform heating. For high viscosities the rigid shell component of atmospheric superrotation can be understood in analogy with a pirouette. During spin up angular momentum is transferred to the planet. For low iscosities, the process is reversed. A tendency toward geostrophy, combined with increase of surface pressure toward the poles (due to meridional mass transport), induces the atmosphere to subrotate temporarily at lower altitudes. Resultant viscous shear near the surface permits angular momentum to flow from the planet into the atmosphere propagating upwards to produce high altitude superrotation rates.
Planetary Boundary Layer Simulation Using TASS

NASA Technical Reports Server (NTRS)

Schowalter, David G.; DeCroix, David S.; Lin, Yuh-Lang; Arya, S. Pal; Kaplan, Michael

1996-01-01

Boundary conditions to an existing large-eddy simulation model have been changed in order to simulate turbulence in the atmospheric boundary layer. Several options are now available, including the use of a surface energy balance. In addition, we compare convective boundary layer simulations with the Wangara and Minnesota field experiments as well as with other model results. We find excellent agreement of modelled mean profiles of wind and temperature with observations and good agreement for velocity variances. Neutral boundary simulation results are compared with theory and with previously used models. Agreement with theory is reasonable, while agreement with previous models is excellent.
MANTLE CONVECTION, PLATE TECTONICS, AND VOLCANISM ON HOT EXO-EARTHS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Summeren, Joost; Conrad, Clinton P.; Gaidos, Eric, E-mail: summeren@hawaii.edu

Recently discovered exoplanets on close-in orbits should have surface temperatures of hundreds to thousands of Kelvin. They are likely tidally locked and synchronously rotating around their parent stars and, if an atmosphere is absent, have surface temperature contrasts of many hundreds to thousands of Kelvin between permanent day and night sides. We investigated the effect of elevated surface temperature and strong surface temperature contrasts for Earth-mass planets on the (1) pattern of mantle convection, (2) tectonic regime, and (3) rate and distribution of partial melting, using numerical simulations of mantle convection with a composite viscous/pseudo-plastic rheology. Our simulations indicate thatmore » if a close-in rocky exoplanet lacks an atmosphere to redistribute heat, a {approx}>400 K surface temperature contrast can maintain an asymmetric degree 1 pattern of mantle convection in which the surface of the planet moves preferentially toward subduction zones on the cold night side. The planetary surface features a hemispheric dichotomy, with plate-like tectonics on the night side and a continuously evolving mobile lid on the day side with diffuse surface deformation and vigorous volcanism. If volcanic outgassing establishes an atmosphere and redistributes heat, plate tectonics is globally replaced by diffuse surface deformation and volcanism accelerates and becomes distributed more uniformly across the planetary surface.« less
Performance of convolutional codes on fading channels typical of planetary entry missions

NASA Technical Reports Server (NTRS)

Modestino, J. W.; Mui, S. Y.; Reale, T. J.

1974-01-01

The performance of convolutional codes in fading channels typical of the planetary entry channel is examined in detail. The signal fading is due primarily to turbulent atmospheric scattering of the RF signal transmitted from an entry probe through a planetary atmosphere. Short constraint length convolutional codes are considered in conjunction with binary phase-shift keyed modulation and Viterbi maximum likelihood decoding, and for longer constraint length codes sequential decoding utilizing both the Fano and Zigangirov-Jelinek (ZJ) algorithms are considered. Careful consideration is given to the modeling of the channel in terms of a few meaningful parameters which can be correlated closely with theoretical propagation studies. For short constraint length codes the bit error probability performance was investigated as a function of E sub b/N sub o parameterized by the fading channel parameters. For longer constraint length codes the effect was examined of the fading channel parameters on the computational requirements of both the Fano and ZJ algorithms. The effects of simple block interleaving in combatting the memory of the channel is explored, using the analytic approach or digital computer simulation.
Mississippi Coastal Improvements Program; Evaluation of Barrier Island Restoration Efforts

DTIC Science & Technology

2013-09-01

Cardone 2007). In addition, atmospheric pressure forcing was not applied in these simulations. ERDC TR-13-12 39 Figure 3-6. The grid around Ship...TC96 Planetary Boundary Layer (PBL) model ( Cardone et al. 1992; Thompson and Cardone 1996) generates a time-series of wind and atmospheric pressure...D. T. Resio, R. A. Leuttich, C. Dawson, V. J. Cardone , A. T. Cox, M. D. Powell, H. J. Westerink, and H. J. Roberts. 2010. A high-resolution coupled
Meteoric Material: An Important Component of Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Grebowsky, Joseph M.; Moses, Julianne I.; Pesnell, W. Dean; Vondrak, Richard R. (Technical Monitor)

2001-01-01

Interplanetary dust particles (IDPs) interact with all planetary atmospheres and leave their imprint as perturbations of the background atmospheric chemistry and structure. They lead to layers of metal ions that can become the dominant positively charged species in lower ionospheric regions. Theoretical models and radio occultation measurements provide compelling evidence that such layers exist in all planetary atmospheres. In addition IDP ablation products can affect neutral atmospheric chemistry, particularly at the outer planets where the IDPs supply oxygen compounds like water and carbon dioxide to the upper atmospheres. Aerosol or smoke particles from incomplete ablation or recondensation of ablated IDP vapors may also have a significant impact on atmospheric properties.
BARTTest: Community-Standard Atmospheric Radiative-Transfer and Retrieval Tests

NASA Astrophysics Data System (ADS)

Harrington, Joseph; Himes, Michael D.; Cubillos, Patricio E.; Blecic, Jasmina; Challener, Ryan C.

2018-01-01

Atmospheric radiative transfer (RT) codes are used both to predict planetary and brown-dwarf spectra and in retrieval algorithms to infer atmospheric chemistry, clouds, and thermal structure from observations. Observational plans, theoretical models, and scientific results depend on the correctness of these calculations. Yet, the calculations are complex and the codes implementing them are often written without modern software-verification techniques. The community needs a suite of test calculations with analytically, numerically, or at least community-verified results. We therefore present the Bayesian Atmospheric Radiative Transfer Test Suite, or BARTTest. BARTTest has four categories of tests: analytically verified RT tests of simple atmospheres (single line in single layer, line blends, saturation, isothermal, multiple line-list combination, etc.), community-verified RT tests of complex atmospheres, synthetic retrieval tests on simulated data with known answers, and community-verified real-data retrieval tests.BARTTest is open-source software intended for community use and further development. It is available at https://github.com/ExOSPORTS/BARTTest. We propose this test suite as a standard for verifying atmospheric RT and retrieval codes, analogous to the Held-Suarez test for general circulation models. This work was supported by NASA Planetary Atmospheres grant NX12AI69G, NASA Astrophysics Data Analysis Program grant NNX13AF38G, and NASA Exoplanets Research Program grant NNX17AB62G.
Infrared experiments for spaceborne planetary atmospheres research. Full report

NASA Technical Reports Server (NTRS)

1981-01-01

The role of infrared sensing in atmospheric science is discussed and existing infrared measurement techniques are reviewed. Proposed techniques for measuring planetary atmospheres are criticized and recommended instrument developments for spaceborne investigations are summarized for the following phenomena: global and local radiative budget; radiative flux profiles; winds; temperature; pressure; transient and marginal atmospheres; planetary rotation and global atmospheric activity; abundances of stable constituents; vertical, lateral, and temporal distribution of abundances; composition of clouds and aerosols; radiative properties of clouds and aerosols; cloud microstructure; cloud macrostructure; and non-LTE phenomena.

Simulation of the planetary boundary layer with the UCLA general circulation model

NASA Technical Reports Server (NTRS)

Suarez, M. J.; Arakawa, A.; Randall, D. A.

1981-01-01

A planetary boundary layer (PBL) model is presented which employs a mixed layer entrainment formulation to describe the mass exchange between the mixed layer with the upper, laminar atmosphere. A modified coordinate system couples the mixed layer model with large scale and sub-grid scale processes of a general circulation model. The vertical coordinate is configured as a sigma coordinate with the lower boundary, the top of the PBL, and the prescribed pressure level near the tropopause expressed as coordinate surfaces. The entrainment mass flux is parameterized by assuming the dissipation rate of turbulent kinetic energy to be proportional to the positive part of the generation by convection or mechanical production. The results of a simulation of July are presented for the entire globe.
Magnetospheric structure and atmospheric Joule heating of habitable planets orbiting M-dwarf stars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, O.; Drake, J. J.; Garraffo, C.

2014-07-20

We study the magnetospheric structure and the ionospheric Joule Heating of planets orbiting M-dwarf stars in the habitable zone using a set of magnetohydrodynamic models. The stellar wind solution is used to drive a model for the planetary magnetosphere, which is coupled with a model for the planetary ionosphere. Our simulations reveal that the space environment around close-in habitable planets is extreme, and the stellar wind plasma conditions change from sub- to super-Alfvénic along the planetary orbit. As a result, the magnetospheric structure changes dramatically with a bow shock forming in the super-Alfvénic sectors, while no bow shock forms inmore » the sub-Alfvénic sectors. The planets reside most of the time in the sub-Alfvénic sectors with poor atmospheric protection. A significant amount of Joule Heating is provided at the top of the atmosphere as a result of the intense stellar wind. For the steady-state solution, the heating is about 0.1%-3% of the total incoming stellar irradiation, and it is enhanced by 50% for the time-dependent case. The significant Joule Heating obtained here should be considered in models for the atmospheres of habitable planets in terms of the thickness of the atmosphere, the top-side temperature and density, the boundary conditions for the atmospheric pressure, and particle radiation and transport. Here we assume constant ionospheric Pedersen conductance similar to that of the Earth. The conductance could be greater due to the intense EUV radiation leading to smaller heating rates. We plan to quantify the ionospheric conductance in future study.« less
What we could learn from observations of terrestrial exoplanets

NASA Astrophysics Data System (ADS)

Meadows, Victoria; Schwieterman, Edward; Arney, Giada; Lustig-Yaeger, Jacob; Lincowski, Andrew; Robinson, Tyler D.; Deming, Drake; NASA Astrobiology Institute - Virtual Planetary Laboratory

2016-10-01

Observations of terrestrial exoplanet environments remain an important frontier in comparative planetology. Studies of habitable zone terrestrial planets will set our own Earth in a broader context. Hot, post-runaway terrestrial exoplanets can provide insights into terrestrial planet evolution - and may reveal planetary processes that could mimic signs of life, such as photochemically-produced oxygen. While transmission spectroscopy observations of terrestrial planet atmospheres with JWST will be extremely challenging, they will afford our first chance to characterize the atmospheres of planets orbiting in the habitable zone of M dwarfs. However, due to the effects of refraction, clouds and hazes, JWST will likely sample the stratospheres of habitable zone terrestrial planets, and will not be able to observe the planetary surface or near-surface atmosphere. These limitations will hamper the search for signs of habitability and life, by precluding detection of water vapor in the deep atmosphere, and confining biosignature searches to gases that are prevalent in the stratosphere, such as evenly-mixed O2, or photochemical byproducts of biogenic gases. In contrast, direct imaging missions can potentially probe the entire atmospheric column and planetary surface, and can typically obtain broader wavelength coverage for habitable zone planets orbiting more Sun-like stars, complementing the M dwarf planet observations favored by transmission spectroscopy. In this presentation we will show results from theoretical modeling of terrestrial exoplanet environments for habitable Earth-like, early Earth and highly-evolved hot terrestrial planets - with photochemistry and climates that are driven by host stars of different spectral types. We will also present simulated observations of these planets for both transmission (JWST) and direct imaging (LUVOIR-class) observations. These photometric measurements and spectra help us identify the most - and least - observable features of these planetary environments, and illuminate the strengths and limitations of each class of observation for future terrestrial planet characterization studies.
Numerical Modeling Studies of Wake Vortex Transport and Evolution Within the Planetary Boundary Layer

NASA Technical Reports Server (NTRS)

Lin, Yuh-Lang; Arya, S. Pal; Kaplan, Michael L.; Shen, Shaohua

1998-01-01

In support of the wake vortex effect of the Terminal Area Productivity program, we have put forward four tasks to be accomplished in our proposal. The first task is validation of two-dimensional wake vortex-turbulence interaction. The second task is investigation of three-dimensional interaction between wake vortices and atmospheric boundary layer (ABL) turbulence. The third task is ABL studies. The, fourth task is addition of a Klemp-Durran condition at the top boundary for TASS model. The accomplishment of these tasks will increase our understanding of the dynamics of wake vortex and improve forecasting systems responsible for air safety and efficiency. The first two tasks include following three parts: (a) Determine significant length scale for vortex decay and transport, especially the length scales associated with the onset of Crow instability (Crow, 1970); (b) Study the effects of atmospheric turbulence on the decay of the wake vortices; and (c) Determine the relationships between decay rate, transport properties and atmospheric parameters based on large eddy simulation (LES) results and the observational data. These parameters may include turbulence kinetic energy, dissipation rate, wind shear and atmospheric stratification. The ABL studies cover LES modeling of turbulence structure within planetary boundary layer under transition and stable stratification conditions. Evidences have shown that the turbulence in the stable boundary layer can be highly intermittent and the length scales of eddies are very small compared to those in convective case. We proposed to develop a nesting grid mesh scheme and a modified Klemp-Durran conditions (Klemp and Wilhelmson, 1978) at the top boundary for TASS model to simulate planetary boundary layer under stable stratification conditions. During the past year, our group has made great efforts to carry out the above mentioned four tasks simultaneously. The work accomplished in the last year will be described in the next section.
Dispersion of aerosol particles in the atmosphere: Fukushima

NASA Astrophysics Data System (ADS)

Haszpra, Tímea; Lagzi, István; Tél, Tamás

2013-04-01

Investigation of dispersion and deposition of aerosol particles in the atmosphere is an essential issue, because they have an effect on the biosphere and atmosphere. Moreover, aerosol particles have different transport properties and chemical and physical transformations in the atmosphere compared to gas phase air pollutants. The motion of a particle is described by a set of ordinary differential equations. The large-scale dynamics in the horizontal direction can be described by the equations of passive scalar advection, but in the vertical direction a well-defined terminal velocity should be taken into account as a term added to the vertical wind component. In the planetary boundary layer turbulent diffusion has an important role in the particle dispersion, which is taken into account by adding stochastic terms to the deterministic equations above. Wet deposition is also an essential process in the lower levels of the atmosphere, however, its precise parameterization is a challenge. For the simulations the wind field and other necessary data were taken from the ECMWF ERA-Interim database. In the case of the Fukushima Daiichi nuclear disaster (March-April 2011) radioactive aerosol particles were also released in the planetary boundary layer. Simulations (included the continuous and varying emission from the nuclear power plant) will be presented for the period of 14-23 March. Results show that wet deposition also has to be taken into consideration in the lower levels of the atmosphere. Furthermore, dynamical system characteristics are evaluated for the aerosol particle dynamics. The escape rate of particles was estimated both with and without turbulent diffusion, and in both cases when there was no wet deposition and also when wet deposition was taken into consideration.
Piloted Simulator Tests of a Guidance System which Can Continously Predict Landing Point of a Low L/D Vehicle During Atmosphere Re-Entry

NASA Technical Reports Server (NTRS)

Wingrove, Rodney C.; Coate, Robert E.

1961-01-01

The guidance system for maneuvering vehicles within a planetary atmosphere which was studied uses the concept of fast continuous prediction of the maximum maneuver capability from existing conditions rather than a stored-trajectory technique. used, desired touchdown points are compared with the maximum range capability and heating or acceleration limits, so that a proper decision and choice of control inputs can be made by the pilot. In the method of display and control a piloted fixed simulator was used t o demonstrate the feasibility od the concept and to study its application to control of lunar mission reentries and recoveries from aborts.
Gas chromatographic concepts for the analysis of planetary atmospheres

NASA Technical Reports Server (NTRS)

Valentin, J. R.; Cullers, D. K.; Hall, K. W.; Krekorian, R. L.; Phillips, J. B.

1991-01-01

Over the last few years, new gas chromatographic (GC) concepts were developed for use on board spacecraft or any other restricted environments for determining the chemical composition of the atmosphere and surface material of various planetary bodies. Future NASA Missions include an entry probe that will be sent to Titan and various spacecraft that will land on Mars. In order to be able to properly respond to the mission science requirements and physical restrictions imposed on the instruments by these missions, GC analytical techniques are being developed. Some of these techniques include hardware and mathematical techniques that will improve GC sensitivity and increase the sampling rate of a GC descending through a planetary atmosphere. The technique of Multiplex Gas Chromatography (MGC) is an example of a technique that was studied in a simulated Titan atmosphere. In such an environment, the atmospheric pressure at instrument deployment is estimated to be a few torr. Thus, at such pressures, the small amount of sample that is acquired might not be enough to satisfy the detection requirements of the gas chromatograph. In MGC, many samples are pseudo-randomly introduced to the chromatograph without regard to elution of preceding components. The resulting data is then reduced using mathematical techniques such as cross-correlation of Fourier Transforms. Advantages realized from this technique include: improvement in detection limits of several orders of magnitude and increase in the number of analyses that can be conducted in a given period of time. Results proving the application of MGC at very low pressures emulating the same atmospheric pressures that a Titan Probe will encounter when the instruments are deployed are presented. The sample used contained hydrocarbons that are expected to be found in Titan's atmosphere. In addition, a new selective modulator was developed to monitor water under Martian atmospheric conditions. Since this modulator is selective only to water, the need for a GC column is eliminated. This results in further simplification of the instrument.
Deciphering the Hot Giant Atmospheres Orbiting Nearby Extrasolar Systems with JWST

NASA Astrophysics Data System (ADS)

Afrin Badhan, Mahmuda; Batalha, Natasha; Deming, Drake; Domagal-Goldman, Shawn; HEBRARD, Eric; Kopparapu, Ravi Kumar; Irwin, Patrick Gerard Joseph

2016-10-01

Unique and exotic planets give us an opportunity to understand how planetary systems form and evolve over their lifetime, by placing our own planetary system in the context of the vastly different extrasolar systems that are being continually discovered by present space missions. With orbital separations that are less than one-tenth of the Mercury-Sun distance, these close-in planets provide us with valuable insights about the host stellar atmosphere and planetary atmospheres subjected to their enormous stellar insolation. Observed spectroscopic signatures reveal all spectrally active species in a planet, along with information about its thermal structure and dynamics, allowing us to characterize the planet's atmosphere. NASA's upcoming missions will give us the high-resolution spectra necessary to constrain the atmospheric properties with unprecedented accuracy. However, to interpret the observed signals from exoplanetary transit events with any certainty, we need reliable atmospheric retrieval tools that can model the expected observables adequately. In my work thus far, I have built a Markov Chain Monte Carlo (MCMC) convergence scheme, with an analytical radiative equilibrium formulation for the thermal structures, within the NEMESIS atmospheric modeling tool, to allow sufficient (and efficient) exploration of the parameter space. I also augmented the opacity tables to improve the speed and reliability of retrieval models. I then utilized this upgraded version to infer the pressure-temperature (P-T) structures and volume-mixing ratios (VMRs) of major gas species in hot Jupiter dayside atmospheres, from their emission spectra. I have employed a parameterized thermal structure to retrieve plausible P-T profiles, along with altitude-invariant VMRs. Here I show my retrieval results on published datasets of HD189733b, and compare them with both medium and high spectral resolution JWST/NIRSPEC simulations. In preparation for the upcoming JWST mission, my current work expands on these efforts by exploring the observable impacts of chemistry in the hot Jupiter models and retrievals.
Solar System atlas series on the Eötvös University, Budapest, Hungary: textbooks for space and planetary science education

NASA Astrophysics Data System (ADS)

Berczi, Sz.; Hargitai, H.; Horvath, A.; Illes, E.; Kereszturi, A.; Mortl, M.; Sik, A.; Weidinger, T.; Hegyi, S.; Hudoba, Gy.

Planetary science education needs new forms of teaching. Our group have various initiatives of which a new atlas series about the studies of the Solar System materials, planetary surfaces and atmospheres, instrumental field works with robots (landers, rovers) and other beautiful field work analog studies. Such analog studies are both used in comparative planetology as scientific method and it also plays a key role in planetary science education. With such initiatives the whole system of the knowledge of terrestrial geology can be transformed to the conditions of other planetary worlds. We prepared both courses and their textbooks in Eötvös University in space science education and edited the following educational materials worked out by the members of our space science education and research group: (1): Planetary and Material Maps on: Lunar Rocks, Meteorites (2000); (2): Investigating Planetary Surfaces with the Experimental Space Probe Hunveyor Constructed on the Basis of Surveyor (2001); (3): Atlas of Planetary Bodies (2001); (4): Atlas of Planetary Atmospheres (2002); (5): Space Research and Geometry (2002); (6): Atlas of Micro Environments of Planetary Surfaces (2003); (7): Atlas of Rovers and Activities on Planetary Surfaces (2004); (8): Space Research and Chemistry (2005); (9): Planetary Analog Studies and Simulations: Materials, Terrains, Morphologies, Processes. (2005); References: [1] Bérczi Sz., Hegyi S., Kovács Zs., Fabriczy A., Földi T., Keresztesi M., Cech V., Drommer B., Gránicz K., Hevesi L., Borbola T., Tóth Sz., Németh I., Horváth Cs., Diósy T., Kovács B., Bordás F., Köll˝ Z., Roskó F., Balogh Zs., Koris A., o 1 Imrek Gy. (Bérczi Sz., Kabai S. Eds.) (2002): Concise Atlas of the Solar System (2): From Surveyor to Hunveyor. How we constructed an experimental educational planetary lander model. UNICONSTANT. Budapest-Pécs-Szombathely-Püspökladány. [2] Bérczi Sz., Hargitai H., Illés E., Kereszturi Á., Sik A., Földi T., Hegyi S., Kovács Zs., Mörtl M., Weidinger T. (2004): Concise Atlas of the Solar System (6): Atlas of Microenvironments of Planetary surfaces. ELTE TTK Kozmikus Anyagokat Vizsgáló Ûrkutató Csoport, UNICONSTANT, Budapest-Püspökladány; [3] Szaniszló Bérczi, Henrik Hargitai, Ákos Kereszturi, András Sik (2005): Concise Atlas on the Solar System (3): Atlas of Planetary Bodies. ELTE TTK Kozmikus Anyagokat Vizsgáló Ûrkutató Csoport. Budapest, [4] Szaniszló Bérczi, Tivadar Földi, Péter Gadányi, Arnold Gucsik, Henrik Hargitai, Sándor Hegyi, György Hudoba, Sándor Józsa, Ákos Kereszturi, János Rakonczai, András Sik, György Szakmány, Kálmán Török (2005): Concise Atlas on the Solar System (9): Planetary Analog Studies and Simulations: Materials, Terrains, Morphologies, Processes. (Szaniszló Bérczi, editor) ELTE TTK Kozmikus Anyagokat Vizsgáló Ûrkutató Csoport, UNICONSTANT, Budapest-Püspökladány. 2
New Radiative Transfer Capability in the EPIC Atmospheric Model with Application to Saturn and Uranus

NASA Astrophysics Data System (ADS)

Dowling, Timothy Edward; Greathouse, T. K.; Sussman, M. G.; Chanover, N. J.

2010-10-01

We have adapted radiative transfer (RT) schemes from the gas-giant seasonal models of Greathouse et al. (EGU 2010) and Sussman et al. (AGU 2009) into the EPIC atmospheric model, and applied them to Saturn and Uranus. These additions give EPIC a hierarchy of RT options to account for solar heating via CH4 absorption from 5 microns to the UV, and radiative cooling due to thermal emission of CH4, C2H2, C2H6, and collision-induced opacity between 0 and 1600 cm-1. We have written an IDL tool to calculate radiative-equilibrium T(p) profiles for model initialization. We have ported the versatile DISORT RT model (Stamnes et al. 1988) from Fortran to C, and are incorporating it into an IDL post-processing tool to allow us to create synthetic spectra from EPIC output that accounts for thermal emission, reflected solar light, and aerosol and Rayleigh scattering. We give an update of applications to simulations of middle-atmosphere temperatures for Saturn and zonal-wind spin-up experiments for Uranus. This research is supported by NASA Planetary Atmospheres grant NNX08AE64G and NSF Planetary Astronomy grant AST-0807989.
Visible and near-infrared reflectance spectroscopy of planetary analog materials. Experimental facility at Laboratoire de Planetologie de Grenoble.

NASA Astrophysics Data System (ADS)

Pommerol, A.; Brissaud, O.; Schmitt, B.; Quirico, E.; Doute, S.

2007-08-01

We have developed an original experimental facility designed to measure the bidirectional reflectance spectra of planetary analog materials. These measurements are helpful to interpret the observations of the spectrometers on board space probes in orbit around various Solar System bodies. The central part of the facility is the LPG spectrogonio- radiometer (Brissaud et al., 2004). This instrument provides measurements of samples BRDF (Bidirectional Reflectance Distribution Function) with high photometric and spectrometric accuracy in the spectral range of visible and near-infrared (0.3 - 4.8 microns). Measurements can be made at any value of incidence and emergence angle up to 80°. Azimuth angle is allowed to vary between 0 and 180°. The instrument was recently installed in a cold room allowing ambient temperatures as low as -20°C. This makes possible the measurements on different kinds of water ice samples (slab ice, frost, snow...) and mixtures of minerals and water ice with unprecedented accuracy. We also have designed and built a simulation chamber to measure spectra of samples (water ice and/or minerals) under an atmosphere with perfectly controlled temperature, pressure and composition. The main objective of this last improvement is the study of water exchange between planetary regolith analogs and atmosphere (adsorption/ desorption, condensation/sublimation). Experimental results will mainly apply to Martian water cycle and hydrated mineralogy. This simulation chamber also provides an efficient way to obtain bidirectional reflectance spectra of dry materials (removal of adsorbed water) with implications for planetary bodies without atmospheric or surface water (Titan, asteroids...). The reflectance spectroscopy facility is part of a large panel of instruments and techniques available at Laboratoire de Planetologie de Grenoble that provide complementary measurements on the same samples: infrared transmission spectroscopy of thin ice films, thick liquid and solid samples and samples diluted in KBr pellets, infrared imaging microscope, numerical modeling of bidirectional reflectance spectra using laboratory-measured optical constants. We will present different examples of experimental results obtained on the reflectance spectroscopy facility: - Effects of particle size, mixtures between samples with different albedo and measurement geometries on the water-of-hydration near-infrared absorption signatures with implications for the Martian regolith water content. - BRDF of regolith analogs and natural snow. - Hydration and dehydration of planetary analogs. - Spectra of different kinds of mixtures between water ice and minerals. We will briefly discuss the planetary implications of each of these measurements and detail the future investigations that will be undertaken on our experimental facility.
First International Conference on Laboratory Research for Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Fox, Kenneth (Editor); Allen, John E., Jr. (Editor); Stief, Louis J. (Editor); Quillen, Diana T. (Editor)

1990-01-01

Proceedings of the First International Conference on Laboratory Research for Planetary Atmospheres are presented. The covered areas of research include: photon spectroscopy, chemical kinetics, thermodynamics, and charged particle interactions. This report contains the 12 invited papers, 27 contributed poster papers, and 5 plenary review papers presented at the conference. A list of attendees and a reprint of the Report of the Subgroup on Strategies for Planetary Atmospheres Exploration (SPASE) are provided in two appendices.
Studies on possible propagation of microbial contamination in planetary clouds

NASA Technical Reports Server (NTRS)

Dimmick, R. L.; Chatigny, M. A.; Wolochow, H.

1973-01-01

One of the key parameters in estimation of the probability of contamintion of the outer planets (Jupiter, Saturn, Uranus, etc.) is the probability of growth (Pg) of terrestrial microorganisms on or near these planets. For example, Jupiter appears to have an atmosphere in which some microbial species could metabolize and propagate. This study includes investigation of the likelihood of metabolism and propagation of microbes suspended in dynamic atmospheres. It is directed toward providing experimental information needed to aid in rational estimation of Pg for these outer planets. Current work is directed at demonstration of aerial metabolism under near optimal conditions and tests of propagation in simulated Jovian atmospheres.
Remote sensing of multi-level wind fields with high-energy airborne scanning coherent Doppler lidar.

PubMed

Rothermel, J; Olivier, L; Banta, R; Hardesty, R M; Howell, J; Cutten, D; Johnson, S; Menzies, R; Tratt, D M

1998-01-19

The atmospheric lidar remote sensing groups of NOAA Environmental Technology Laboratory, NASA Marshall Space Flight Center, and Jet Propulsion Laboratory have developed and flown a scanning, 1 Joule per pulse, CO2 coherent Doppler lidar capable of mapping a three-dimensional volume of atmospheric winds and aerosol backscatter in the planetary boundary layer, free troposphere, and lower stratosphere. Applications include the study of severe and non-severe atmospheric flows, intercomparisons with other sensors, and the simulation of prospective satellite Doppler lidar wind profilers. Examples of wind measurements are given for the marine boundary layer and near the coastline of the western United States.
Sensitivity of boundary layer variables to PBL schemes over the central Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xu, L.; Liu, H.; Wang, L.; Du, Q.; Liu, Y.

2017-12-01

Planetary Boundary Layer (PBL) parameterization schemes play critical role in numerical weather prediction and research. They describe physical processes associated with the momentum, heat and humidity exchange between land surface and atmosphere. In this study, two non-local (YSU and ACM2) and two local (MYJ and BouLac) planetary boundary layer parameterization schemes in the Weather Research and Forecasting (WRF) model have been tested over the central Tibetan Plateau regarding of their capability to model boundary layer parameters relevant for surface energy exchange. The model performance has been evaluated against measurements from the Third Tibetan Plateau atmospheric scientific experiment (TIPEX-III). Simulated meteorological parameters and turbulence fluxes have been compared with observations through standard statistical measures. Model results show acceptable behavior, but no particular scheme produces best performance for all locations and parameters. All PBL schemes underestimate near surface air temperatures over the Tibetan Plateau. By investigating the surface energy budget components, the results suggest that downward longwave radiation and sensible heat flux are the main factors causing the lower near surface temperature. Because the downward longwave radiation and sensible heat flux are respectively affected by atmosphere moisture and land-atmosphere coupling, improvements in water vapor distribution and land-atmosphere energy exchange is meaningful for better presentation of PBL physical processes over the central Tibetan Plateau.
ATMOSPHERIC DYNAMICS OF TERRESTRIAL EXOPLANETS OVER A WIDE RANGE OF ORBITAL AND ATMOSPHERIC PARAMETERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaspi, Yohai; Showman, Adam P., E-mail: yohai.kaspi@weizmann.ac.il

The recent discoveries of terrestrial exoplanets and super-Earths extending over a broad range of orbital and physical parameters suggest that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super-Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone—including transitions to Snowball-like states and runaway-greenhouse feedbacks—depend on the equator-to-pole temperature differences, patterns of relativemore » humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, stellar flux, atmospheric mass, surface gravity, optical thickness, and planetary radius affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley and Ferrel cells, and latitudinal temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global climate.« less
The parameterization of the planetary boundary layer in the UCLA general circulation model - Formulation and results

NASA Technical Reports Server (NTRS)

Suarez, M. J.; Arakawa, A.; Randall, D. A.

1983-01-01

A planetary boundary layer (PBL) parameterization for general circulation models (GCMs) is presented. It uses a mixed-layer approach in which the PBL is assumed to be capped by discontinuities in the mean vertical profiles. Both clear and cloud-topped boundary layers are parameterized. Particular emphasis is placed on the formulation of the coupling between the PBL and both the free atmosphere and cumulus convection. For this purpose a modified sigma-coordinate is introduced in which the PBL top and the lower boundary are both coordinate surfaces. The use of a bulk PBL formulation with this coordinate is extensively discussed. Results are presented from a July simulation produced by the UCLA GCM. PBL-related variables are shown, to illustrate the various regimes the parameterization is capable of simulating.
Online Chapmann Layer Calculator for Simulating the Ionosphere with Undergraduate and Graduate Students

NASA Astrophysics Data System (ADS)

Gross, N. A.; Withers, P.; Sojka, J. J.

2014-12-01

The Chapman Layer Model is a "textbook" model of the ionosphere (for example, "Theory of Planetary Atmospheres" by Chamberlain and Hunten, Academic Press (1978)). The model use fundamental assumptions about the neutral atmosphere, the flux of ionizing radiation, and the recombination rate to calculation the ionization rate, and ion/electron density for a single species atmosphere. We have developed a "Chapman Layer Calculator" application that is deployed on the web using Java. It allows the user to see how various parameters control ion density, peak height, and profile of the ionospheric layer. Users can adjust parameters relevant to thermosphere scale height (temperature, gravitational acceleration, molecular weight, neutral atmosphere density) and to Extreme Ultraviolet solar flux (reference EUV, distance from the Sun, and solar Zenith Angle) and then see how the layer changes. This allows the user to simulate the ionosphere on other planets, by adjusting to the appropriate parameters. This simulation has been used as an exploratory activity for the NASA/LWS - Heliophysics Summer School 2014 and has an accompanying activity guide.
Laboratory investigation on super-Earths atmospheres

NASA Astrophysics Data System (ADS)

Erculiani, M. S.; Claudi, R. U.; Lessio, L.; Farisato, G.; Giro, E.; Cocola, L.; Billi, D.; D'alessandro, M.; Pace, E.; Schierano, D.; Benatti, S.; Bonavita, M.; Galletta, G.

2014-04-01

In the framework of Atmosphere in a Test Tube, at the Astronomical Observatory of Padova (INAF) we are going to perform experiments aimed to understand the possible modification of the atmosphere by photosynthetic biota present on the planet surface. This goal can be achieved simulating M star planetary environmental conditions. The bacteria that are being studied are Acaryochloris marina, Chroococcidiopsis spp. and Halomicronema hingdechloris. Tests will be performed with LISA or MINI-LISA ambient simulator in the laboratory of the Padova Astronomic Observatory. In this paper we describe the whole road map to follow in order to perform experiments and to obtain useful data to be compared with the real ones that will be obtained by the future space missions. Starting by a fiducial experiment we will modify either environmental and thermodynamical properties in order to simulate both real irradiation by an M star and gas mixture mimicing super earths atmospheres. These laboratory tests could be used as a guideline in order to understand whether chemical disequilibrium of O2, CO2 and CH4 could be ascribed to biotic life forms.
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1991-01-01

Laboratory measurements of microwave and millimeter wave properties of the simulated atmosphere of the outer planets and their satellites has continued. One of the focuses is on the development of a radiative transfer model of the Jovian atmosphere at wavelengths from 1 mm to 10 cm. This modeling effort led to laboratory measurements of the millimeter wave opacity of hydrogen sulfide (H2S) under simulated Jovian conditions. Descriptions of the modeling effort, the Laboratory experiment, and the observations are presented. Correlative studies of measurements with Pioneer-Venus radio occultation measurements with longer wavelength emission measurements have provided new ways for characterizing temporal and spatial variations in the abundance of both gases H2SO4 and SO2, and for modeling their roles in the subcloud atmosphere. Laboratory measurements were conducted on 1.35 cm (and 13 cm) opacity of gaseous SO2 and absorptivity of gaseous SO2 at the 3.2 mm wavelength under simulated Venus conditions. Laboratory measurements were completed on millimeter wave dielectric properties of liquid H2SO4, in order to model the effects of the opacity of the clouds of Venus onto millimeter wave emission spectrum.

Quasi-Biennial Oscillation and Solar Cycle Influences over the Winter Arctic Simulated by the WACCM4 Model

NASA Astrophysics Data System (ADS)

Li, K. F.; Limpasuvan, T. L.; Limpasuvan, V.; Tung, K. K.; Yung, Y. L.

2017-12-01

Observations show that the quasi-biennial oscillation (QBO) and the 11-year solar cycle perturb the polar vortex via planetary wave convergence at high latitudes, a mechanism first proposed by Holton and Tan in 1980. Their perturbations lead to increases of stratospheric sudden warming events, and hence observable increases in temperature and ozone abundance in the polar vortex, during the easterly phase of QBO and the solar maximum. Here we simulate the changes in the polar atmosphere using the Whole Atmosphere Community Climate Model 4 (WACCM4) with the prescribed QBO and 11-year solar cycle forcing. The simulation is diagnosed in four groups: westerly QBO phase and solar minimum, westerly QBO phase and solar maximum, easterly QBO phase and solar minimum, and easterly QBO phase and solar maximum. The simulated changes in temperature and ozone are compared with satellite observations.
Applications of acoustic-gravity waves numerical modeling to tsunami signals observed by gravimetry satellites in very low orbit

NASA Astrophysics Data System (ADS)

Brissaud, Q.; Garcia, R.; Sladen, A.; Martin, R.; Komatitsch, D.

2016-12-01

Acoustic and gravity waves propagating in planetary atmospheres have been studied intensively as markers of specific phenomena (tectonic events, explosions) or as contributors to atmosphere dynamics. To get a better understanding of the physics behind these dynamic processes, both acoustic and gravity waves propagation should be modeled in an attenuating and windy 3D atmosphere from the ground all the way to the upper thermosphere. Thus, in order to provide an efficient numerical tool at the regional or global scale we introduce a high-order finite-difference time domain (FDTD) approach that relies on the linearized compressible Navier-Stokes equations with spatially non constant physical parameters (density, viscosities and speed of sound) and background velocities (wind). We present applications of these simulations to the propagation of gravity waves generated by tsunamis for realistic cases for which atmospheric models are extracted from empirical models including variations with altitude of atmospheric parameters, and tsunami forcing at the ocean surface is extracted from shallow water simulations. We describe the specific difficulties induced by the size of the simulation, the boundary conditions and the spherical geometry and compare the simulation outputs to data gathered by gravimetric satellites crossing gravity waves generated by tsunamis.
Composition of LHB Comets and Their Influence on the Early Earth Atmosphere Composition

NASA Technical Reports Server (NTRS)

Tornow, C.; Kupper, S.; Ilgner, M.; Kuehrt, E.; Motschmann, U.

2011-01-01

Two main processes were responsible for the composition of this atmosphere: chemical evolution of the volatile fraction of the accretion material forming the planet and the delivery of gasses to the planetary surface by impactors during the late heavy bombardment (LHB). The amount and composition of the volatile fraction influences the outgassing of the Earth mantle during the last planetary formation period. A very weakened form of outgassing activity can still be observed today by examining the composition of volcanic gasses. An enlightenment of the second process is based on the sparse records of the LHB impactors resulting from the composition of meteorites, observed cometary comas, and the impact material found on the Moon. However, for an assessment of the influence of the outgassing on the one hand and the LHB event on the other, one has to supplement the observations with numerical simulations of the formation of volatiles and their incorporation into the accretion material which is the precursors of planetary matter, comets and asteroids. These simulations are performed with a combined hydrodynamic-chemical model of the solar nebula (SN). We calculate the chemical composition of the gas and dust phase of the SN. From these data, we draw conclusions on the upper limits of the water content and the amount of carbon and nitrogen rich volatiles incorporated later into the accretion material. Knowing these limits we determine the portion of major gas compounds delivered during the LHB and compare it with the related quantities of the outgassed species.
REVIEWS OF TOPICAL PROBLEMS: Generation of large-scale eddies and zonal winds in planetary atmospheres

NASA Astrophysics Data System (ADS)

Onishchenko, O. G.; Pokhotelov, O. A.; Astafieva, N. M.

2008-06-01

The review deals with a theoretical description of the generation of zonal winds and vortices in a turbulent barotropic atmosphere. These large-scale structures largely determine the dynamics and transport processes in planetary atmospheres. The role of nonlinear effects on the formation of mesoscale vortical structures (cyclones and anticyclones) is examined. A new mechanism for zonal wind generation in planetary atmospheres is discussed. It is based on the parametric generation of convective cells by finite-amplitude Rossby waves. Weakly turbulent spectra of Rossby waves are considered. The theoretical results are compared to the results of satellite microwave monitoring of the Earth's atmosphere.
Modeling the Martian neutron and gamma-ray leakage fluxes using Geant4

NASA Astrophysics Data System (ADS)

Pirard, Benoit; Desorgher, Laurent; Diez, Benedicte; Gasnault, Olivier

A new evaluation of the Martian neutron and gamma-ray (continuum and line) leakage fluxes has been performed using the Geant4 code. Even if numerous studies have recently been carried out with Monte Carlo methods to characterize planetary radiation environments, only a few however have been able to reproduce in detail the neutron and gamma-ray spectra observed in orbit. We report on the efforts performed to adapt and validate the Geant4-based PLAN- ETOCOSMICS code for use in planetary neutron and gamma-ray spectroscopy data analysis. Beside the advantage of high transparency and modularity common to Geant4 applications, the new code uses reviewed nuclear cross section data, realistic atmospheric profiles and soil layering, as well as specific effects such as gravity acceleration for low energy neutrons. Results from first simulations are presented for some Martian reference compositions and show a high consistency with corresponding neutron and gamma-ray spectra measured on board Mars Odyssey. Finally we discuss the advantages and perspectives of the improved code for precise simulation of planetary radiation environments.
Formation of Amino Acids and Nucleotide Bases in a Titan Atmosphere Simulation Experiment

PubMed Central

Yelle, R.V.; Buch, A.; Carrasco, N.; Cernogora, G.; Dutuit, O.; Quirico, E.; Sciamma-O'Brien, E.; Smith, M.A.; Somogyi, Á.; Szopa, C.; Thissen, R.; Vuitton, V.

2012-01-01

Abstract The discovery of large (>100 u) molecules in Titan's upper atmosphere has heightened astrobiological interest in this unique satellite. In particular, complex organic aerosols produced in atmospheres containing C, N, O, and H, like that of Titan, could be a source of prebiotic molecules. In this work, aerosols produced in a Titan atmosphere simulation experiment with enhanced CO (N2/CH4/CO gas mixtures of 96.2%/2.0%/1.8% and 93.2%/5.0%/1.8%) were found to contain 18 molecules with molecular formulae that correspond to biological amino acids and nucleotide bases. Very high-resolution mass spectrometry of isotopically labeled samples confirmed that C4H5N3O, C4H4N2O2, C5H6N2O2, C5H5N5, and C6H9N3O2 are produced by chemistry in the simulation chamber. Gas chromatography–mass spectrometry (GC-MS) analyses of the non-isotopic samples confirmed the presence of cytosine (C4H5N3O), uracil (C5H4N2O2), thymine (C5H6N2O2), guanine (C5H5N5O), glycine (C2H5NO2), and alanine (C3H7NO2). Adenine (C5H5N5) was detected by GC-MS in isotopically labeled samples. The remaining prebiotic molecules were detected in unlabeled samples only and may have been affected by contamination in the chamber. These results demonstrate that prebiotic molecules can be formed by the high-energy chemistry similar to that which occurs in planetary upper atmospheres and therefore identifies a new source of prebiotic material, potentially increasing the range of planets where life could begin. Key Words: Astrochemistry—Planetary atmospheres—Titan—Astrobiology. Astrobiology 12, 809–817. PMID:22917035
Climatic Evolution and Habitability of Terrestrial Planets: Perspectives from Coupled Atmosphere-Mantle Systems

NASA Astrophysics Data System (ADS)

Basu Sarkar, D.; Moore, W. B.

2016-12-01

A multitude of factors including the distance from the host star and the stage of planetary evolution affect planetary climate and habitability. The complex interactions between the atmosphere and dynamics of the deep interior of the planets along with stellar fluxes present a formidable challenge. This work employs simplified approaches to address these complex issues in a systematic way. To be specific, we are investigating the coupled evolution of atmosphere and mantle dynamics. The overarching goal here is to simulate the evolutionary history of the terrestrial planets, for example Venus, Earth and Mars. This research also aims at deciphering the history of Venus-like runaway greenhouse and thus explore the possibility of cataclysmic shifts in climate of Earth-like planets. We focus on volatile cycling within the solid planets to understand the role of carbon/water in climatic and tectonic outcomes of such planets. In doing so, we are considering the feedbacks in the coupled mantle-atmosphere system. The primary feedback between the atmosphere and mantle is the surface temperature established by the greenhouse effect, which regulates the temperature gradient that drives the mantle convection and controls the rate at which volatiles are exchanged through weathering. We start our models with different initial assumptions to determine the final climate outcomes within a reasonable parameter space. Currently, there are very few planetary examples, to sample the climate outcomes, however this will soon change as exoplanets are discovered and examined. Therefore, we will be able to work with a significant number of potential candidates to answer questions like this one: For every Earth is there one Venus? ten? a thousand?
The Ultimate Spitzer Phase Curve Survey: Cross-Planetary Comparison of Heat-Redistribution Efficiencies

NASA Astrophysics Data System (ADS)

Fraine, Jonathan D.; Stevenson, Kevin; Bean, Jacob; Deming, Drake; Fortney, Jonathan; Kataria, Tiffany; Kempton, Eliza; Lewis, Nikole K.; Line, Michael; Morley, Caroline; Rauscher, Emily; Showman, Adam; Feng, Katherina

2018-01-01

Exoplanet phase curves provide a wealth of information about exoplanet atmospheres, including longitudinal constraints on atmospheric composition, thermal structure, and energy transport, that continue to open new doors of scientific inquiry and propel future investigations. The measured heat redistribution efficiency (or ability to transport energy from a planet's highly-irradiated dayside to its eternally-dark nightside) shows considerable variation between exoplanets. Theoretical models predict a correlation between heat redistribution efficiency and planet temperature; however, the latest results are inconsistent with current predictions from 3D atmospheric simulations. We will present preliminary results from a 660-hour Spitzer phase curve survey program that targeted six short-period extrasolar planets. By comparing short periods exoplanets over a range of equilibrium temperatures, we can begin to disentangle the effects of planetary rotation and energy budget on a planet's thermal properties. We will discuss how the measured planet temperature and rotation rate affect the heat redistribution efficiencies, examine trends in the phase curve peak offset, and discuss cloud coverage constraints. Our Spitzer observations will provide valuable information for predicting and interpreting future, JWST-era observations.
Effective mie-scattering and CO2 absorption in the dust-laden Martian atmosphere and its impact on radiative-convective temperature changes in the lower scale heights

NASA Technical Reports Server (NTRS)

Pallmann, A. J.

1976-01-01

A time dependent computer model of radiative-convective-conductive heat transfer in the Martian ground-atmosphere system was refined by incorporating an intermediate line strength CO2 band absorption which together with the strong-and weak-line approximation closely simulated the radiative transmission through a vertically inhomogeneous stratification. About 33,000 CO2 lines were processed to cover the spectral range of solar and planetary radiation. Absorption by silicate dust particulates, was taken into consideration to study its impact on the ground-atmosphere temperature field as a function of time. This model was subsequently attuned to IRIS, IR-radiometric and S-band occultation data. Satisfactory simulations of the measured IRIS spectra were accomplished for the dust-free condition. In the case of variable dust loads, the simulations were sufficiently fair so that some inferences into the effect of dust on temperature were justified.
Comparative pick-up ion distributions at Mars and Venus: Consequences for atmospheric deposition and escape

NASA Astrophysics Data System (ADS)

Curry, Shannon M.; Luhmann, Janet; Ma, Yingjuan; Liemohn, Michael; Dong, Chuanfei; Hara, Takuya

2015-09-01

Without the shielding of a substantial intrinsic dipole magnetic field, the atmospheres of Mars and Venus are particularly susceptible to similar atmospheric ion energization and scavenging processes. However, each planet has different attributes and external conditions controlling its high altitude planetary ion spatial and energy distributions. This paper describes analogous test particle simulations in background MHD fields that allow us to compare the properties and fates, precipitation or escape, of the mainly O+ atmospheric pick-up ions at Mars and Venus. The goal is to illustrate how atmospheric and planetary scales affect the upper atmospheres and space environments of our terrestrial planet neighbors. The results show the expected convection electric field-related hemispheric asymmetries in both precipitation and escape, where the degree of asymmetry at each planet is determined by the planetary scale and local interplanetary field strength. At Venus, the kinetic treatment of O+ reveals a strong nightside source of precipitation while Mars' crustal fields complicate the simple asymmetry in ion precipitation and drive a dayside source of precipitation. The pickup O+ escape pattern at both Venus and Mars exhibits low energy tailward escape, but Mars exhibits a prominent, high energy 'polar plume' feature in the hemisphere of the upward convection electric field while the Venus ion wake shows only a modest poleward concentration. The overall escape is larger at Venus than Mars (2.1 ×1025 and 4.3 ×1024 at solar maximum, respectively), but the efficiency (likelihood) of O+ escaping is 2-3 times higher at Mars. The consequences of these comparisons for pickup ion related atmospheric energy deposition, loss rates, and detection on spacecraft including PVO, VEX, MEX and MAVEN are considered. In particular, both O+ precipitation and escape show electric field controlled asymmetries that grow with energy, while the O+ fluxes and energy spectra at selected spatial locations show characteristic signatures of the pickup related acceleration and precipitation.
Laboratory experiments in the study of the chemistry of the outer planets.

PubMed

Scattergood, T W

1987-01-01

The investigation of chemical evolution of bodies in our solar system has, in the past, included observations, theoretical modeling, and laboratory simulations. Of these programs, the last one has been the most criticized due to the inherent difficulties in accurately recreating alien environments in the laboratory. Processes such as wall reactions and changes in chemistry due to difficulties in achieving realistic conditions of temperature, pressure, composition, and energy flux may yield results which are not truly representative of the systems being modeled. However, many laboratory studies have been done which have yielded data useful in planetary science. Gross simulations of atmospheric chemistry have placed constraints on the nature of complex molecules expected in planetary atmospheres. More precise studies of specific chemical processes have provided information about the sources and properties of product gases and aerosols. Determinations of basic properties such as spectral features and reaction rate constants yield data useful in the interpretation of observations and in computational modeling. Alone, and in conjunction with modeling, laboratory experiments will continue to be used to further our understanding of the outer solar system, and some experiments that need to be done are listed.
Parameterization of planetary wave breaking in the middle atmosphere

NASA Technical Reports Server (NTRS)

Garcia, Rolando R.

1991-01-01

A parameterization of planetary wave breaking in the middle atmosphere has been developed and tested in a numerical model which includes governing equations for a single wave and the zonal-mean state. The parameterization is based on the assumption that wave breaking represents a steady-state equilibrium between the flux of wave activity and its dissipation by nonlinear processes, and that the latter can be represented as linear damping of the primary wave. With this and the additional assumption that the effect of breaking is to prevent further amplitude growth, the required dissipation rate is readily obtained from the steady-state equation for wave activity; diffusivity coefficients then follow from the dissipation rate. The assumptions made in the derivation are equivalent to those commonly used in parameterizations for gravity wave breaking, but the formulation in terms of wave activity helps highlight the central role of the wave group velocity in determining the dissipation rate. Comparison of model results with nonlinear calculations of wave breaking and with diagnostic determinations of stratospheric diffusion coefficients reveals remarkably good agreement, and suggests that the parameterization could be useful for simulating inexpensively, but realistically, the effects of planetary wave transport.
The interactive role of subsynoptic scale jet sreak and planetary boundary layer adjustments in organizing an apparently isolated convective complex

NASA Technical Reports Server (NTRS)

Kaplan, M. L.; Zack, J. W.; Wong, V. C.; Tuccillo, J. J.; Coats, G. D.

1982-01-01

A mesoscale atmospheric simulation system is described that is being developed in order to improve the simulation of subsynoptic and mesoscale adjustments associated with cyclogenesis, severe storm development, and significant atmospheric transport processes. Present emphasis in model development is in the parameterization of physical processes, time-dependent boundary conditions, sophisticated initialization and analysis procedures, nested grid solutions, and applications software development. Basic characteristics of the system as of March 1982 are listed. In a case study, the Grand Island tornado outbreak of 3 June 1980 is considered in substantial detail. Results of simulations with a mesoscale atmospheric simulation system indicate that over the high plains subtle interactions between existing jet streaks and deep well mixed boundary layers can lead to well organized patterns of mesoscale divergence and pressure falls. The amplitude and positioning of these mesoscale features is a function of the subtle nonlinear interaction between the pre-existing jet-streak and deep well mixed boundary layers. Model results for the case study indicate that the model has the potential for forecasting the precursor mesoscale convective environment.
The Formation of Solid Particles from their Gas-Phase Molecular Precursors in Cosmic Environments with NASA Ames' COSmIC Facility

NASA Technical Reports Server (NTRS)

Salama, Farid

2014-01-01

We present and discuss the unique characteristics and capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory. COSmIC stands for Cosmic Simulation Chamber and is dedicated to the study of molecules and ions under the low temperature and high vacuum conditions that are required to simulate interstellar, circumstellar and planetary physical environments in space. COSmIC integrates a variety of state-of-the-art instruments that allow forming, processing and monitoring simulated space conditions for planetary, circumstellar and interstellar materials in the laboratory. COSmIC is composed of a Pulsed Discharge Nozzle (PDN) expansion that generates a free jet supersonic expansion coupled to two ultrahigh-sensitivity, complementary in situ diagnostics: a Cavity Ring Down Spectroscopy (CRDS) system for photonic detection and a Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection. Recent, unique, laboratory astrophysics results that were obtained using the capabilities of COSmIC will be discussed, in particular the progress that have been achieved in monitoring in the laboratory the formation of solid gains from their gas-phase molecular precursors in environments as varied as stellar/circumstellar outflow and planetary atmospheres. Plans for future, next generation, laboratory experiments on cosmic molecules and grains in the growing field of laboratory astrophysics will also be addressed as well as the implications of these studies for current and upcoming space missions.
Planetary atmospheres and aurorae

NASA Technical Reports Server (NTRS)

Moos, H. W.; Encrenaz, TH.

1987-01-01

Observations of planetary atmospheres and auroras obtained by the IUE satellite observatory during the first 10 years of its operation are reviewed. Topics examined include the value of UV studies of atmospheric phenomena, the kinds of observations available prior to the launch of IUE in 1978, the composition and structure of the upper atmospheres below the homopause, the effects of the magnetosphere on the atmosphere above the homopause, excitation processes, and fundamental questions and scientific goals. Data on Jupiter, Saturn, Neptune and Uranus, and the Io plasma torus are presented in tables and graphs and briefly characterized. It is pointed out that the IUE has greatly advanced knowledge of the plantary atmospheres, despite the fact that its design was not optimized for planetary observations.
Simulating dynamics of δ13C of CO2 in the planetary boundary layer over a boreal forest region: covariation between surface fluxes and atmospheric mixing

NASA Astrophysics Data System (ADS)

Chen, Baozhang; Chen, Jing M.; Tans, Pieter P.; Huang, Lin

2006-11-01

Stable isotopes of CO2 contain unique information on the biological and physical processes that exchange CO2 between terrestrial ecosystems and the atmosphere. Ecosystem exchange of carbon isotopes with the atmosphere is correlated diurnally and seasonally with the planetary boundary layer (PBL) dynamics. The strength of this kind of covariation affects the vertical gradient of δ13C and thus the global δ13C distribution pattern. We need to understand the various processes involved in transport/diffusion of carbon isotope ratio in the PBL and between the PBL and the biosphere and the troposphere. In this study, we employ a one-dimensional vertical diffusion/transport atmospheric model (VDS), coupled to an ecosystem isotope model (BEPS-EASS) to simulate dynamics of 13CO2 in the PBL over a boreal forest region in the vicinity of the Fraserdale (FRD) tower (49°52'29.9''N, 81°34'12.3''W) in northern Ontario, Canada. The data from intensive campaigns during the growing season in 1999 at this site are used for model validation in the surface layer. The model performance, overall, is satisfactory in simulating the measured data over the whole course of the growing season. We examine the interaction of the biosphere and the atmosphere through the PBL with respect to δ13C on diurnal and seasonal scales. The simulated annual mean vertical gradient of δ13C in the PBL in the vicinity of the FRD tower was about 0.25‰ in 1999. The δ13C vertical gradient exhibited strong diurnal (29%) and seasonal (71%) variations that do not exactly mimic those of CO2. Most of the vertical gradient (96.5% +/-) resulted from covariation between ecosystem exchange of carbon isotopes and the PBL dynamics, while the rest (3.5%+/-) was contributed by isotopic disequilibrium between respiration and photosynthesis. This disequilibrium effect on δ13C of CO2 dynamics in PBL, moreover, was confined to the near surface layers (less than 350 m).
Trajectory Simulation of Meteors Assuming Mass Loss and Fragmentation

NASA Technical Reports Server (NTRS)

Allen, Gary A., Jr.; Prabhu, Dinesh K.; Saunders, David A

2015-01-01

Program used to simulate atmospheric flight trajectories of entry capsules [1] Includes models of atmospheres of different planetary destinations - Earth, Mars, Venus, Jupiter, Saturn, Uranus, Titan, ... Solves 3--degrees of freedom (3DoF) equations for a single body treated as a point mass. Also supports 6-DoF trajectory simula4on and Monte Carlo analyses. Uses Fehlberg--Runge--Kuna (4th-5th order) time integraion with automaic step size control. Includes rotating spheroidal planet with gravitational field having a J2 harmonic. Includes a variety of engineering aerodynamic and heat flux models. Capable of specifying events - heatshield jettison, parachute deployment, etc. - at predefined altitudes or Mach number. Has material thermal response models of typical aerospace materials integrated.
Demonstration of an Aerocapture GN and C System Through Hardware-in-the-Loop Simulations

NASA Technical Reports Server (NTRS)

Masciarelli, James; Deppen, Jennifer; Bladt, Jeff; Fleck, Jeff; Lawson, Dave

2010-01-01

Aerocapture is an orbit insertion maneuver in which a spacecraft flies through a planetary atmosphere one time using drag force to decelerate and effect a hyperbolic to elliptical orbit change. Aerocapture employs a feedback Guidance, Navigation, and Control (GN&C) system to deliver the spacecraft into a precise postatmospheric orbit despite the uncertainties inherent in planetary atmosphere knowledge, entry targeting and aerodynamic predictions. Only small amounts of propellant are required for attitude control and orbit adjustments, thereby providing mass savings of hundreds to thousands of kilograms over conventional all-propulsive techniques. The Analytic Predictor Corrector (APC) guidance algorithm has been developed to steer the vehicle through the aerocapture maneuver using bank angle control. Through funding provided by NASA's In-Space Propulsion Technology Program, the operation of an aerocapture GN&C system has been demonstrated in high-fidelity simulations that include real-time hardware in the loop, thus increasing the Technology Readiness Level (TRL) of aerocapture GN&C. First, a non-real-time (NRT), 6-DOF trajectory simulation was developed for the aerocapture trajectory. The simulation included vehicle dynamics, gravity model, atmosphere model, aerodynamics model, inertial measurement unit (IMU) model, attitude control thruster torque models, and GN&C algorithms (including the APC aerocapture guidance). The simulation used the vehicle and mission parameters from the ST-9 mission. A 2000 case Monte Carlo simulation was performed and results show an aerocapture success rate of greater than 99.7%, greater than 95% of total delta-V required for orbit insertion is provided by aerodynamic drag, and post-aerocapture orbit plane wedge angle error is less than 0.5 deg (3-sigma). Then a real-time (RT), 6-DOF simulation for the aerocapture trajectory was developed which demonstrated the guidance software executing on a flight-like computer, interfacing with a simulated IMU and simulated thrusters, with vehicle dynamics provided by an external simulator. Five cases from the NRT simulations were run in the RT simulation environment. The results compare well to those of the NRT simulation thus verifying the RT simulation configuration. The results of the above described simulations show the aerocapture maneuver using the APC algorithm can be accomplished reliably and the algorithm is now at TRL-6. Flight validation is the next step for aerocapture technology development.
Vibrational-Rotational Spectroscopy For Planetary Atmospheres, volume 1

NASA Technical Reports Server (NTRS)

Mumma, M. J. (Editor); Fox, K. (Editor); Hornstein, J. (Editor)

1982-01-01

Comprehensive information on the composition and dynamics of the varied planetary atmospheres is summarized. New observations resulted in new demands for supporting laboratory studies. Spectra observed from spacecraft used to interpret planetary atmospheric structure measurements, to aid in greenhouse and cloud physics calculations, and to plan future experiments are discussed. Current findings and new ideas of physicists, chemists, and planetry astronomers relating to the knowledge of the structure of things large and small, of planets and of molecules are summarized.
Global Lidar Measurements of Clouds and Aerosols from Space Using the Geoscience Laser Altimeter System (GLAS)

NASA Technical Reports Server (NTRS)

Hlavka, Dennis L.; Palm, S. P.; Welton, E. J.; Hart, W. D.; Spinhirne, J. D.; McGill, M.; Mahesh, A.; Starr, David OC. (Technical Monitor)

2001-01-01

The Geoscience Laser Altimeter System (GLAS) is scheduled for launch on the ICESat satellite as part of the NASA EOS mission in 2002. GLAS will be used to perform high resolution surface altimetry and will also provide a continuously operating atmospheric lidar to profile clouds, aerosols, and the planetary boundary layer with horizontal and vertical resolution of 175 and 76.8 m, respectively. GLAS is the first active satellite atmospheric profiler to provide global coverage. Data products include direct measurements of the heights of aerosol and cloud layers, and the optical depth of transmissive layers. In this poster we provide an overview of the GLAS atmospheric data products, present a simulated GLAS data set, and show results from the simulated data set using the GLAS data processing algorithm. Optical results from the ER-2 Cloud Physics Lidar (CPL), which uses many of the same processing algorithms as GLAS, show algorithm performance with real atmospheric conditions during the Southern African Regional Science Initiative (SAFARI 2000).

Computational Aerothermodynamics in Aeroassist Applications

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.

2001-01-01

Aeroassisted planetary entry uses atmospheric drag to decelerate spacecraft from super-orbital to orbital or suborbital velocities. Numerical simulation of flow fields surrounding these spacecraft during hypersonic atmospheric entry is required to define aerothermal loads. The severe compression in the shock layer in front of the vehicle and subsequent, rapid expansion into the wake are characterized by high temperature, thermo-chemical nonequilibrium processes. Implicit algorithms required for efficient, stable computation of the governing equations involving disparate time scales of convection, diffusion, chemical reactions, and thermal relaxation are discussed. Robust point-implicit strategies are utilized in the initialization phase; less robust but more efficient line-implicit strategies are applied in the endgame. Applications to ballutes (balloon-like decelerators) in the atmospheres of Venus, Mars, Titan, Saturn, and Neptune and a Mars Sample Return Orbiter (MSRO) are featured. Examples are discussed where time-accurate simulation is required to achieve a steady-state solution.
1-D Photochemical Modeling of the Martian Atmosphere: Seasonal Variations

NASA Astrophysics Data System (ADS)

Boxe, C.; Emmanuel, S.; Hafsa, U.; Griffith, E.; Moore, J.; Tam, J.; Khan, I.; Cai, Z.; Bocolod, B.; Zhao, J.; Ahsan, S.; Tang, N.; Bartholomew, J.; Rafi, R.; Caltenco, K.; Smith, K.; Rivas, M.; Ditta, H.; Alawlaqi, H.; Rowley, N.; Khatim, F.; Ketema, N.; Strothers, J.; Diallo, I.; Owens, C.; Radosavljevic, J.; Austin, S. A.; Johnson, L. P.; Zavala-Gutierrez, R.; Breary, N.; Saint-Hilaire, D.; Skeete, D.; Stock, J.; Blue, S.; Gurung, D.; Salako, O.

2016-12-01

High school and undergraduate students, representative of academic institutions throughout USA's Tri-State Area (New York, New Jersey, Connecticut), utilize Caltech/JPL's one-dimensional atmospheric, photochemical models. These sophisticated models, were built over the course of the last four decades, describing all planetary bodies in our Solar System and selected extrasolar planets. Specifically, students employed the Martian one-dimensional photochemical model to assess the seasonal variability of molecules in its atmosphere. Students learned the overall model construct, running a baseline simulation, and fluctuating parameters (e.g., obliquity, orbital eccentricity) which affects the incoming solar radiation on Mars, temperature and pressure induce by seasonal variations. Students also attain a `real-world' experience that exemplifies the required level of coding competency and innovativeness needed for building an environment that can simulate observations and forecast. Such skills permeate STEM-related occupations that model systems and/or predict how that system may/will behave.
The global reference atmospheric model, mod 2 (with two scale perturbation model)

NASA Technical Reports Server (NTRS)

Justus, C. G.; Hargraves, W. R.

1976-01-01

The Global Reference Atmospheric Model was improved to produce more realistic simulations of vertical profiles of atmospheric parameters. A revised two scale random perturbation model using perturbation magnitudes which are adjusted to conform to constraints imposed by the perfect gas law and the hydrostatic condition is described. The two scale perturbation model produces appropriately correlated (horizontally and vertically) small scale and large scale perturbations. These stochastically simulated perturbations are representative of the magnitudes and wavelengths of perturbations produced by tides and planetary scale waves (large scale) and turbulence and gravity waves (small scale). Other new features of the model are: (1) a second order geostrophic wind relation for use at low latitudes which does not "blow up" at low latitudes as the ordinary geostrophic relation does; and (2) revised quasi-biennial amplitudes and phases and revised stationary perturbations, based on data through 1972.
The Effect of Orbital Configuration on the Possible Climates and Habitability of Kepler-62f.

PubMed

Shields, Aomawa L; Barnes, Rory; Agol, Eric; Charnay, Benjamin; Bitz, Cecilia; Meadows, Victoria S

2016-06-01

As lower-mass stars often host multiple rocky planets, gravitational interactions among planets can have significant effects on climate and habitability over long timescales. Here we explore a specific case, Kepler-62f (Borucki et al., 2013 ), a potentially habitable planet in a five-planet system with a K2V host star. N-body integrations reveal the stable range of initial eccentricities for Kepler-62f is 0.00 ≤ e ≤ 0.32, absent the effect of additional, undetected planets. We simulate the tidal evolution of Kepler-62f in this range and find that, for certain assumptions, the planet can be locked in a synchronous rotation state. Simulations using the 3-D Laboratoire de Météorologie Dynamique (LMD) Generic global climate model (GCM) indicate that the surface habitability of this planet is sensitive to orbital configuration. With 3 bar of CO2 in its atmosphere, we find that Kepler-62f would only be warm enough for surface liquid water at the upper limit of this eccentricity range, providing it has a high planetary obliquity (between 60° and 90°). A climate similar to that of modern-day Earth is possible for the entire range of stable eccentricities if atmospheric CO2 is increased to 5 bar levels. In a low-CO2 case (Earth-like levels), simulations with version 4 of the Community Climate System Model (CCSM4) GCM and LMD Generic GCM indicate that increases in planetary obliquity and orbital eccentricity coupled with an orbital configuration that places the summer solstice at or near pericenter permit regions of the planet with above-freezing surface temperatures. This may melt ice sheets formed during colder seasons. If Kepler-62f is synchronously rotating and has an ocean, CO2 levels above 3 bar would be required to distribute enough heat to the nightside of the planet to avoid atmospheric freeze-out and permit a large enough region of open water at the planet's substellar point to remain stable. Overall, we find multiple plausible combinations of orbital and atmospheric properties that permit surface liquid water on Kepler-62f. Extrasolar planets-Habitability-Planetary environments. Astrobiology 16, 443-464.
The Effect of Orbital Configuration on the Possible Climates and Habitability of Kepler-62f

PubMed Central

Barnes, Rory; Agol, Eric; Charnay, Benjamin; Bitz, Cecilia; Meadows, Victoria S.

2016-01-01

Abstract As lower-mass stars often host multiple rocky planets, gravitational interactions among planets can have significant effects on climate and habitability over long timescales. Here we explore a specific case, Kepler-62f (Borucki et al., 2013), a potentially habitable planet in a five-planet system with a K2V host star. N-body integrations reveal the stable range of initial eccentricities for Kepler-62f is 0.00 ≤ e ≤ 0.32, absent the effect of additional, undetected planets. We simulate the tidal evolution of Kepler-62f in this range and find that, for certain assumptions, the planet can be locked in a synchronous rotation state. Simulations using the 3-D Laboratoire de Météorologie Dynamique (LMD) Generic global climate model (GCM) indicate that the surface habitability of this planet is sensitive to orbital configuration. With 3 bar of CO2 in its atmosphere, we find that Kepler-62f would only be warm enough for surface liquid water at the upper limit of this eccentricity range, providing it has a high planetary obliquity (between 60° and 90°). A climate similar to that of modern-day Earth is possible for the entire range of stable eccentricities if atmospheric CO2 is increased to 5 bar levels. In a low-CO2 case (Earth-like levels), simulations with version 4 of the Community Climate System Model (CCSM4) GCM and LMD Generic GCM indicate that increases in planetary obliquity and orbital eccentricity coupled with an orbital configuration that places the summer solstice at or near pericenter permit regions of the planet with above-freezing surface temperatures. This may melt ice sheets formed during colder seasons. If Kepler-62f is synchronously rotating and has an ocean, CO2 levels above 3 bar would be required to distribute enough heat to the nightside of the planet to avoid atmospheric freeze-out and permit a large enough region of open water at the planet's substellar point to remain stable. Overall, we find multiple plausible combinations of orbital and atmospheric properties that permit surface liquid water on Kepler-62f. Key Words: Extrasolar planets—Habitability—Planetary environments. Astrobiology 16, 443–464. PMID:27176715
Astronomical, physical, and meteorological parameters for planetary atmospheres

NASA Technical Reports Server (NTRS)

Allison, Michael; Travis, Larry D.

1986-01-01

A newly compiled table of astronomical, physical, and meteorological parameters for planetary atmospheres is presented. Formulae and explanatory notes for their application and a complete listing of sources are also given.
Improved atmospheric 3D BSDF model in earthlike exoplanet using ray-tracing based method

NASA Astrophysics Data System (ADS)

Ryu, Dongok; Kim, Sug-Whan; Seong, Sehyun

2012-10-01

The studies on planetary radiative transfer computation have become important elements to disk-averaged spectral characterization of potential exoplanets. In this paper, we report an improved ray-tracing based atmospheric simulation model as a part of 3-D earth-like planet model with 3 principle sub-components i.e. land, sea and atmosphere. Any changes in ray paths and their characteristics such as radiative power and direction are computed as they experience reflection, refraction, transmission, absorption and scattering. Improved atmospheric BSDF algorithms uses Q.Liu's combined Rayleigh and aerosol Henrey-Greenstein scattering phase function. The input cloud-free atmosphere model consists of 48 layers with vertical absorption profiles and a scattering layer with their input characteristics using the GIOVANNI database. Total Solar Irradiance data are obtained from Solar Radiation and Climate Experiment (SORCE) mission. Using aerosol scattering computation, we first tested the atmospheric scattering effects with imaging simulation with HRIV, EPOXI. Then we examined the computational validity of atmospheric model with the measurements of global, direct and diffuse radiation taken from NREL(National Renewable Energy Laboratory)s pyranometers and pyrheliometers on a ground station for cases of single incident angle and for simultaneous multiple incident angles of the solar beam.
Formation of spectral lines in planetary atmospheres. I - Theory for cloudy atmospheres: Application to Venus.

NASA Technical Reports Server (NTRS)

Hunt, G. E.

1972-01-01

The theory of the formation of spectral lines in a cloudy planetary atmosphere is studied in detail. It is shown that models based upon homogeneous, isotropically scattering atmospheres cannot be used to reproduce observed spectroscopic features of phase effect and the shape of spectral lines for weak and strong bands. The theory must, therefore, be developed using an inhomogeneous (gravitational) model of a planetary atmosphere, accurately incorporating all the physical processes of radiative transfer. Such a model of the lower Venus atmosphere, consistent with our present knowledge, is constructed. The results discussed in this article demonstrate the effects of the parameters that describe the atmospheric model on the spectroscopic features of spectral line profile and phase effect, at visible and near infrared wavelengths. This information enables us to develop a comprehensive theory of line formation in a Venus atmosphere.
A population study of hot Jupiter atmospheres

NASA Astrophysics Data System (ADS)

Tsiaras, A.; Waldmann, I. P.; Zingales, T.; Rocchetto, M.; Damiano, M.; Karpouzas, K.; Tinetti, G.; McKemmish, L. K.; Tennyson, J.; Yrchenko, S. N.

2017-09-01

In the past two decades, we have learnt that every star hosts more than one planet. While the hunt for new exoplanets is on-going, the current sample of more than 3500 confirmed planets reveals a wide spectrum of planetary characteristics. While small planets appear to be the most common, the big and gaseous planets play a key role in the process of planetary formation. We present here the analysis of 30 gaseous extra-solar planets, with temperatures between 600 and 2400 K and radii between 0.35 and 1.9 Jupiter radii. These planets were spectroscopically observed with the Wide Field Camera 3 on-board the Hubble Space Telescope, which is currently one of the most successful instruments for observing exoplanetary atmospheres. The quality of the HST/WFC3 spatially-scanned data combined with our specialised analysis tools, allows us to create the largest and most self-consistent sample of exoplanetary transmission spectra to date and study the collective behaviour of warm and hot gaseous planets rather than isolated case-studies. We define a new metric, the Atmospheric Detectability Index (ADI) to evaluate the statistical significance of an atmospheric detection and find statistically significant atmospheres around 16 planets. For most of the Jupiters in our sample we find the detectability of their atmospheres to be dependent on the planetary radius but not on the planetary mass. This indicates that planetary gravity is a secondary factor in the evolution of planetary atmospheres. We detect the presence of water vapour in all the statistically detectable atmospheres and we cannot rule out its presence in the atmospheres of the others. In addition, TiO and/or VO signatures are detected with 4σ confidence in WASP-76 b, and they are most likely present on WASP-121 b. We find no correlation between expected signal-to-noise and atmospheric detectability for most targets. This has important implications for future large-scale surveys.
Accounting planetary habitability using non standard conditions. Impact on the definition of Habitable Zone

NASA Astrophysics Data System (ADS)

Simoncini, E.; Delgado-Bonal, A.; Martin-Torres, F. J.

2012-12-01

Although during the 1960s, atmospheric disequilibrium has been proposed as a sign of habitability of Earth and, in general, of a planet [1, 2], no calculation has been done until now. In order to provide a first evaluation of Earth's atmospheric disequilibrium, we have developed a new formulation to account for the thermodynamic conditions of a wide range of planetary atmospheres, from terrestrial planets to icy satellites, to hot exoplanets. Using this new formulation, we estimate the departure of different planetary atmospheres from their equilibrium conditions, computing the dissipation of free energy due to all chemical processes [3]. In particular, we focus on the effect of our proposed changes on O2/CO2 chemistry (comparing Io satellite atmosphere and Earth Mesosphere), N2 (Venus, Earth and Titan) and H2O stability on terrestrial planets and exoplanets. Our results have an impact in the definition of Habitable Zone by considering appropriate physical-chemical conditions of planetary atmospheres. References [1] J. E. Lovelock, A physical basis for life detection experiments. Nature, 207, 568-570 (1965). [2] J. E. Lovelock, Thermodynamics and the recognition of alien biospheres. Proc. R. Soc. Lond., B. 189, 167 - 181 (1975). [3] Simoncini E., Delgado-Bonal A., Martin-Torres F.J., Accounting thermodynamic conditions in chemical models of planetary atmospheres. Submitted to Astrophysical Journal.
Properties of thermospheric gravity waves on earth, Venus and Mars

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Harris, I.; Pesnell, W. D.

1992-01-01

A spectral model with spherical harmonics and Fourier components that can simulate atmospheric perturbations in the global geometry of a multiconstituent atmosphere is presented. The boundaries are the planetary surface where the transport velocities vanish and the exobase where molecular heat conduction and viscosity dominate. The time consuming integration of the conservation equations is reduced to computing the transfer function (TF) which describes the dynamic properties of the medium divorced from the complexities in the temporal and horizontal variations of the excitation source. Given the TF, the atmospheric response to a chosen source distribution is then obtained in short order. Theoretical studies are presented to illuminate some properties of gravity waves on earth, Venus and Mars.
The Twenty-Fifth Lunar and Planetary Science Conference. Part 2: H-O

NASA Technical Reports Server (NTRS)

1994-01-01

Various papers on lunar and planetary science are presented, covering such topics as: planetary geology, lunar geology, meteorites, shock loads, cometary collisions, planetary mapping, planetary atmospheres, chondrites, chondrules, planetary surfaces, impact craters, lava flow, achondrites, geochemistry, stratigraphy, micrometeorites, tectonics, mineralogy, petrology, geomorphology, and volcanology.
The Twenty-Fifth Lunar and Planetary Science Conference. Part 1: A-G

NASA Technical Reports Server (NTRS)

1994-01-01

Papers from the conference are presented, and the topics covered include the following: planetary geology, meteorites, planetary composition, meteoritic composition, planetary craters, lunar craters, meteorite craters, petrology, petrography, volcanology, planetary crusts, geochronology, geomorphism, mineralogy, lithology, planetary atmospheres, impact melts, volcanoes, planetary evolution, tectonics, planetary mapping, asteroids, comets, lunar soil, lunar rocks, lunar geology, metamorphism, chemical composition, meteorite craters, and planetary mantles.
The dynamical core of the Aeolus 1.0 statistical-dynamical atmosphere model: validation and parameter optimization

NASA Astrophysics Data System (ADS)

Totz, Sonja; Eliseev, Alexey V.; Petri, Stefan; Flechsig, Michael; Caesar, Levke; Petoukhov, Vladimir; Coumou, Dim

2018-02-01

We present and validate a set of equations for representing the atmosphere's large-scale general circulation in an Earth system model of intermediate complexity (EMIC). These dynamical equations have been implemented in Aeolus 1.0, which is a statistical-dynamical atmosphere model (SDAM) and includes radiative transfer and cloud modules (Coumou et al., 2011; Eliseev et al., 2013). The statistical dynamical approach is computationally efficient and thus enables us to perform climate simulations at multimillennia timescales, which is a prime aim of our model development. Further, this computational efficiency enables us to scan large and high-dimensional parameter space to tune the model parameters, e.g., for sensitivity studies.Here, we present novel equations for the large-scale zonal-mean wind as well as those for planetary waves. Together with synoptic parameterization (as presented by Coumou et al., 2011), these form the mathematical description of the dynamical core of Aeolus 1.0.We optimize the dynamical core parameter values by tuning all relevant dynamical fields to ERA-Interim reanalysis data (1983-2009) forcing the dynamical core with prescribed surface temperature, surface humidity and cumulus cloud fraction. We test the model's performance in reproducing the seasonal cycle and the influence of the El Niño-Southern Oscillation (ENSO). We use a simulated annealing optimization algorithm, which approximates the global minimum of a high-dimensional function.With non-tuned parameter values, the model performs reasonably in terms of its representation of zonal-mean circulation, planetary waves and storm tracks. The simulated annealing optimization improves in particular the model's representation of the Northern Hemisphere jet stream and storm tracks as well as the Hadley circulation.The regions of high azonal wind velocities (planetary waves) are accurately captured for all validation experiments. The zonal-mean zonal wind and the integrated lower troposphere mass flux show good results in particular in the Northern Hemisphere. In the Southern Hemisphere, the model tends to produce too-weak zonal-mean zonal winds and a too-narrow Hadley circulation. We discuss possible reasons for these model biases as well as planned future model improvements and applications.
Submillimeter Planetary Atmospheric Chemistry Exploration Sounder

NASA Technical Reports Server (NTRS)

Schlecht, Erich T.; Allen, Mark A.; Gill, John J.; Choonsup, Lee; Lin, Robert H.; Sin, Seth; Mehdi, Imran; Siegel, Peter H.; Maestrini, Alain

2013-01-01

Planetary Atmospheric Chemistry Exploration Sounder (SPACES), a high-sensitivity laboratory breadboard for a spectrometer targeted at orbital planetary atmospheric analysis. The frequency range is 520 to 590 GHz, with a target noise temperature sensitivity of 2,500 K for detecting water, sulfur compounds, carbon compounds, and other atmospheric constituents. SPACES is a prototype for a powerful tool for the exploration of the chemistry and dynamics of any planetary atmosphere. It is fundamentally a single-pixel receiver for spectral signals emitted by the relevant constituents, intended to be fed by a fixed or movable telescope/antenna. Its front-end sensor translates the received signal down to the 100-MHz range where it can be digitized and the data transferred to a spectrum analyzer for processing, spectrum generation, and accumulation. The individual microwave and submillimeter wave components (mixers, LO high-powered amplifiers, and multipliers) of SPACES were developed in cooperation with other programs, although with this type of instrument in mind. Compared to previous planetary and Earth science instruments, its broad bandwidth (approx. =.13%) and rapid tunability (approx. =.10 ms) are new developments only made possible recently by the advancement in submillimeter circuit design and processing at JPL.
Planetary Surface Instruments Workshop

NASA Technical Reports Server (NTRS)

Meyer, Charles (Editor); Treiman, Allan H. (Editor); Kostiuk, Theodor (Editor)

1996-01-01

This report on planetary surface investigations and planetary landers covers: (1) the precise chemical analysis of solids; (2) isotopes and evolved gas analyses; (3) planetary interiors; planetary atmospheres from within as measured by landers; (4) mineralogical examination of extraterrestrial bodies; (5) regoliths; and (6) field geology/processes.
CONVECTION IN CONDENSIBLE-RICH ATMOSPHERES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, F.; Pierrehumbert, R. T., E-mail: fding@uchicago.edu

2016-05-01

Condensible substances are nearly ubiquitous in planetary atmospheres. For the most familiar case—water vapor in Earth’s present climate—the condensible gas is dilute, in the sense that its concentration is everywhere small relative to the noncondensible background gases. A wide variety of important planetary climate problems involve nondilute condensible substances. These include planets near or undergoing a water vapor runaway and planets near the outer edge of the conventional habitable zone, for which CO{sub 2} is the condensible. Standard representations of convection in climate models rely on several approximations appropriate only to the dilute limit, while nondilute convection differs in fundamentalmore » ways from dilute convection. In this paper, a simple parameterization of convection valid in the nondilute as well as dilute limits is derived and used to discuss the basic character of nondilute convection. The energy conservation properties of the scheme are discussed in detail and are verified in radiative-convective simulations. As a further illustration of the behavior of the scheme, results for a runaway greenhouse atmosphere for both steady instellation and seasonally varying instellation corresponding to a highly eccentric orbit are presented. The latter case illustrates that the high thermal inertia associated with latent heat in nondilute atmospheres can damp out the effects of even extreme seasonal forcing.« less
Theory of Tumbling Bodies Entering Planetary Atmospheres with Application to Probe Vehicles and the Australian Tektites

NASA Technical Reports Server (NTRS)

Tobak, Murray; Peterson, Victor L.

1964-01-01

The tumbling motion of aerodynamically stable bodies entering planetary atmospheres is analyzed considering that the tumbling, its arrest, and the subsequent oscillatory motion are governed by the equation for the fifth Painleve' transcendent. Results based on the asymptotic behavior of the transcendent are applied to study (1) the oscillatory behavior of planetary probe vehicles in relation to aerodynamic heating and loads and (2) the dynamic behavior of the Australian tektites on entering the Earth's atmosphere, under the hypothesis that their origin was the Moon.
Characterizing Earth Analogs in Reflected Light: Atmospheric Retrieval Studies for Future Space Telescopes

NASA Astrophysics Data System (ADS)

Feng, Y. Katherina; Robinson, Tyler D.; Fortney, Jonathan J.; Lupu, Roxana E.; Marley, Mark S.; Lewis, Nikole K.; Macintosh, Bruce; Line, Michael R.

2018-05-01

Space-based high-contrast imaging mission concepts for studying rocky exoplanets in reflected light are currently under community study. We develop an inverse modeling framework to estimate the science return of such missions given different instrument design considerations. By combining an exoplanet albedo model, instrument noise model, and ensemble Markov chain Monte Carlo sampler, we explore retrievals of atmospheric and planetary properties for Earth twins as a function of signal-to-noise ratio (S/N) and resolution (R). Our forward model includes Rayleigh-scattering, single-layer water clouds with patchy coverage, and pressure-dependent absorption due to water vapor, oxygen, and ozone. We simulate data at R = 70 and 140 from 0.4 to 1.0 μm with S/N = 5, 10, 15, and 20 at 550 nm (i.e., for HabEx/LUVOIR-type instruments). At these same S/Ns, we simulate data for WFIRST paired with a starshade, which includes two photometric points between 0.48 and 0.6 μm and R = 50 spectroscopy from 0.6 to 0.97 μm. Given our noise model for WFIRST-type detectors, we find that weak detections of water vapor, ozone, and oxygen can be achieved with observations with at least R = 70/S/N = 15 or R = 140/S/N = 10 for improved detections. Meaningful constraints are only achieved with R = 140/S/N = 20 data. The WFIRST data offer limited diagnostic information, needing at least S/N = 20 to weakly detect gases. Most scenarios place limits on planetary radius but cannot constrain surface gravity and, thus, planetary mass.
Trapping of water vapor from an atmosphere by condensed silicate matter formed by high-temperature pulse vaporization

NASA Technical Reports Server (NTRS)

Gerasimov, M. V.; Dikov, Yu. P.; Yakovlev, O. I.; Wlotzka, F.

1993-01-01

The origin of planetary atmospheres is thought to be the result of bombardment of a growing planet by massive planetesimals. According to some models, the accumulation of released water vapor and/or carbon dioxide can result in the formation of a dense and hot primordial atmosphere. Among source and sink processes of atmospheric water vapor the formation of hydroxides was considered mainly as rehydration of dehydrated minerals (foresterite and enstatite). From our point of view, the formation of hydroxides is not limited to rehydration. Condensation of small silicate particles in a spreading vapor cloud and their interaction with a wet atmosphere can also result in the origin of hydrated phases which have no genetic connections with initial water bearing minerals. We present results of two experiments of a simulated interaction of condensed silicate matter which originated during vaporization of dry clinopyroxene in a wet helium atmosphere.

Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z

NASA Technical Reports Server (NTRS)

1993-01-01

Papers from the conference are presented, and the topics covered include the following: planetary geology, meteorites, planetary composition, meteoritic composition, planetary craters, lunar craters, meteorite craters, petrology, petrography, volcanology, planetary crusts, geochronology, geomorphism, mineralogy, lithology, planetary atmospheres, impact melts, K-T Boundary Layer, volcanoes, planetary evolution, tectonics, planetary mapping, asteroids, comets, lunar soil, lunar rocks, lunar geology, metamorphism, chemical composition, meteorite craters, planetary mantles, and space exploration.
Toward a coherent set of radiative transfer tools for the analysis of planetary atmospheres .

NASA Astrophysics Data System (ADS)

Grassi, D.; Ignatiev, N. I.; Zasova, L. V.; Piccioni, G.; Adriani, A.; Moriconi, M. L.; Sindoni, G.; D'Aversa, E.; Snels, M.; Altieri, F.; Migliorini, A.; Stefani, S.; Politi, R.; Dinelli, B. M.; Geminale, A.; Rinaldi, G.

The IAPS experience in the field of analysis of planetary atmospheres from visual and infrared measurements dates back to the early '90 in the frame of the IFSI participation to the Mars96 program. Since then, the forward models as well as retrieval schemes have been constantly updated and have seen a large usage in the analysis of data from Mars Express, Venus Express and Cassini missions. At the eve of a new series of missions (Juno, ExoMars, JUICE), we review the tools currently available to the Italian community, the latest developments and future perspectives. Notably, recent reanalysis of PFS-MEX and VIRTIS-VEX data \\citep{Grassi2014} leaded to a full convergence of complete Bayesian retrieval schemes and approximate forward models, achieving a degree of maturity and flexibility quite close to the state-of-the-art NEMESIS package \\citep{Irwin2007}. As a test case, the retrieval code for the JIRAM observations of hot-spots will be discussed, with extensive validation against simulated observations.
Atmospheric planetary-wave response to external forcing

NASA Technical Reports Server (NTRS)

Stevens, D. E.; Reiter, E. R.

1983-01-01

A summary of the progress report is given, covering the following areas: atmospheric circulation, planetary waves, adaption of the model to the Cyber 205, continental heat flux anomalies, and nonlinear evolution of inertial instabilities in the tropics.
Midlatitude atmospheric responses to Arctic sensible heat flux anomalies in Community Climate Model, Version 4: Atmospheric Response to Arctic SHFs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mills, Catrin M.; Cassano, John J.; Cassano, Elizabeth N.

Possible linkages between Arctic sea ice loss and midlatitude weather are strongly debated in the literature. We analyze a coupled model simulation to assess the possibility of Arctic ice variability forcing a midlatitude response, ensuring consistency between atmosphere, ocean, and ice components. We work with weekly running mean daily sensible heat fluxes with the self-organizing map technique to identify Arctic sensible heat flux anomaly patterns and the associated atmospheric response, without the need of metrics to define the Arctic forcing or measure the midlatitude response. We find that low-level warm anomalies during autumn can build planetary wave patterns that propagatemore » downstream into the midlatitudes, creating robust surface cold anomalies in the eastern United States.« less
Finite-Difference Modeling of Acoustic and Gravity Wave Propagation in Mars Atmosphere: Application to Infrasounds Emitted by Meteor Impacts

NASA Astrophysics Data System (ADS)

Garcia, Raphael F.; Brissaud, Quentin; Rolland, Lucie; Martin, Roland; Komatitsch, Dimitri; Spiga, Aymeric; Lognonné, Philippe; Banerdt, Bruce

2017-10-01

The propagation of acoustic and gravity waves in planetary atmospheres is strongly dependent on both wind conditions and attenuation properties. This study presents a finite-difference modeling tool tailored for acoustic-gravity wave applications that takes into account the effect of background winds, attenuation phenomena (including relaxation effects specific to carbon dioxide atmospheres) and wave amplification by exponential density decrease with height. The simulation tool is implemented in 2D Cartesian coordinates and first validated by comparison with analytical solutions for benchmark problems. It is then applied to surface explosions simulating meteor impacts on Mars in various Martian atmospheric conditions inferred from global climate models. The acoustic wave travel times are validated by comparison with 2D ray tracing in a windy atmosphere. Our simulations predict that acoustic waves generated by impacts can refract back to the surface on wind ducts at high altitude. In addition, due to the strong nighttime near-surface temperature gradient on Mars, the acoustic waves are trapped in a waveguide close to the surface, which allows a night-side detection of impacts at large distances in Mars plains. Such theoretical predictions are directly applicable to future measurements by the INSIGHT NASA Discovery mission.
Planetary Radio Interferometry and Doppler Experiment (PRIDE) for Planetary Atmospheric Studies

NASA Astrophysics Data System (ADS)

Bocanegra Bahamon, Tatiana; Cimo, Giuseppe; Duev, Dmitry; Gurvits, Leonid; Molera Calves, Guifre; Pogrebenko, Sergei

2015-04-01

The Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a technique that allows the determination of the radial velocity and lateral coordinates of planetary spacecraft with very high accuracy (Duev, 2012). The setup of the experiment consists of several ground stations from the European VLBI Network (EVN) located around the globe, which simultaneously perform Doppler tracking of a spacecraft carrier radio signal, and are subsequently processed in a VLBI-style in phase referencing mode. Because of the accurate examination of the changes in phase and amplitude of the radio signal propagating from the spacecraft to the multiple stations on Earth, the PRIDE technique can be used for several fields of planetary research, among which planetary atmospheric studies, gravimetry and ultra-precise celestial mechanics of planetary systems. In the study at hand the application of this technique for planetary atmospheric investigations is demonstrated. As a test case, radio occultation experiments were conducted with PRIDE having as target ESA's Venus Express, during different observing sessions with multiple ground stations in April 2012 and March 2014. Once each of the stations conducts the observation, the raw data is delivered to the correlation center at the Joint Institute for VLBI in Europe (JIVE) located in the Netherlands. The signals are processed with a high spectral resolution and phase detection software package from which Doppler observables of each station are derived. Subsequently the Doppler corrected signals are correlated to derive the VLBI observables. These two sets of observables are used for precise orbit determination. The reconstructed orbit along with the Doppler observables are used as input for the radio occultation processing software, which consists of mainly two modules, the geometrical optics module and the ray tracing inversion module, from which vertical density profiles, and subsequently, temperature and pressure profiles of Venus' atmosphere were derived. The demonstration of the capability of PRIDE as a radio science instrument for planetary atmospheric studies is developed in the framework of the upcoming ESA's JUICE mission to study Jupiter's system.
Interstellar and Planetary Analogs in the Laboratory

NASA Technical Reports Server (NTRS)

Salama, Farid

2013-01-01

We present and discuss the unique capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to investigate the interaction of ionizing radiation (UV, charged particles) with molecular species (neutral molecules, radicals and ions) and carbonaceous grains in the Solar System and in the Interstellar Medium (ISM). COSmIC stands for Cosmic Simulation Chamber, a laboratory chamber where interstellar and planetary analogs are generated, processed and analyzed. It is composed of a pulsed discharge nozzle (PDN) expansion that generates a free jet supersonic expansion in a plasma cavity coupled to two ultrahigh-sensitivity, complementary in situ diagnostics: a cavity ring down spectroscopy (CRDS) system for photonic detection and a Reflectron time-of-flight mass spectrometer (ReTOF-MS) for mass detection. This setup allows the study of molecules, ions and solids under the low temperature and high vacuum conditions that are required to simulate some interstellar, circumstellar and planetary physical environments providing new fundamental insights on the molecular level into the processes that are critical to the chemistry in the ISM, circumstellar and planet forming regions, and on icy objects in the Solar System. Recent laboratory results that were obtained using COSmIC will be discussed, in particular the progress that have been achieved in monitoring in the laboratory the formation of solid particles from their gas-phase molecular precursors in environments as varied as circumstellar outflow and planetary atmospheres.
Planetary Surface-Atmosphere Interactions

NASA Astrophysics Data System (ADS)

Merrison, J. P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.

2013-09-01

Planetary bodies having an accessible solid surface and significant atmosphere, such as Earth, Mars, Venus, Titan, share common phenomenology. Specifically wind induced transport of surface materials, subsequent erosion, the generation and transport of solid aerosols which leads both to chemical and electrostatic interaction with the atmosphere. How these processes affect the evolution of the atmosphere and surface will be discussed in the context of general planetology and the latest laboratory studies will be presented.
Studies of planetary upper atmospheres through occultations

NASA Technical Reports Server (NTRS)

Elliot, J. L.

1982-01-01

The structure, composition, dynamics and energy balance of planetary upper atmospheres through interpretation of steller occultation data from Uranus is discussed. The wave-optical problem of modelling strong scintillation for arbitrary turbulent atmospheres is studied, as well as influence of turbulence. It was concluded that quasi-global features of atmospheric structure are accurately determined by numerical inversion. Horizontally inhomogeneous structures are filtered out and have little effect on temperature profiles.
Simulations of GCR interactions within planetary bodies using GEANT4

NASA Astrophysics Data System (ADS)

Mesick, K.; Feldman, W. C.; Stonehill, L. C.; Coupland, D. D. S.

2017-12-01

On planetary bodies with little to no atmosphere, Galactic Cosmic Rays (GCRs) can hit the body and produce neutrons primarily through nuclear spallation within the top few meters of the surfaces. These neutrons undergo further nuclear interactions with elements near the planetary surface and some will escape the surface and can be detected by landed or orbiting neutron radiation detector instruments. The neutron leakage signal at fast neutron energies provides a measure of average atomic mass of the near-surface material and in the epithermal and thermal energy ranges is highly sensitive to the presence of hydrogen. Gamma-rays can also escape the surface, produced at characteristic energies depending on surface composition, and can be detected by gamma-ray instruments. The intra-nuclear cascade (INC) that occurs when high-energy GCRs interact with elements within a planetary surface to produce the leakage neutron and gamma-ray signals is highly complex, and therefore Monte Carlo based radiation transport simulations are commonly used for predicting and interpreting measurements from planetary neutron and gamma-ray spectroscopy instruments. In the past, the simulation code that has been widely used for this type of analysis is MCNPX [1], which was benchmarked against data from the Lunar Neutron Probe Experiment (LPNE) on Apollo 17 [2]. In this work, we consider the validity of the radiation transport code GEANT4 [3], another widely used but open-source code, by benchmarking simulated predictions of the LPNE experiment to the Apollo 17 data. We consider the impact of different physics model options on the results, and show which models best describe the INC based on agreement with the Apollo 17 data. The success of this validation then gives us confidence in using GEANT4 to simulate GCR-induced neutron leakage signals on Mars in relevance to a re-analysis of Mars Odyssey Neutron Spectrometer data. References [1] D.B. Pelowitz, Los Alamos National Laboratory, LA-CP-05-0369, 2005. [2] G.W. McKinney et al, Journal of Geophysics Research, 111, E06004, 2006. [3] S. Agostinelli et al, Nuclear Instrumentation and Methods A, 506, 2003.
Low Cost Entry, Descent, and Landing (EDL) Instrumentation for Planetary Missions

NASA Technical Reports Server (NTRS)

Hwang, H. H.; Munk, M. M.; Dillman, R. A.; Mahzari, M.; Swanson, G. T.; White, T. R.

2016-01-01

Missions that involve traversing through a planetary atmosphere are unique opportunities that require elements of entry, descent, and landing (EDL). Many aspects of the EDL sequence are qualified using analysis and simulation due to the inability to conduct appropriate ground tests, however validating flight data are often lacking, especially for missions not involving Earth re-entry. NASA has made strategic decisions to collect EDL flight data in order to improve future mission designs. For example, MEDLI1 and EFT-1 gathered hypersonic pressure and in-depth temperature data in the thermal protection system (TPS). However, the ability to collect EDL flight data from the smaller competed missions, such as Discovery and New Frontiers, has been limited in part due to the Principal Investigator-managed cost-caps (PIMCC). The recent NASA decision to consider EDL instrumentation earlier in the mission design cycle led to the inclusion of a requirement in the Discovery 2014 Announcement of Opportunity which requires all missions that involve EDL to include an Engineering Science Investigation (ESI).2 The ESI would involve sensors for aerothermal environment and TPS; atmosphere, aerodynamics, and flight dynamics; atmospheric decelerator; and/or vehicle structure.3 The ESI activity would be funded outside of the PIMCC.
Simulations of the Boreal Winter Upper Mesosphere and Lower Thermosphere With Meteorological Specifications in SD-WACCM-X

NASA Astrophysics Data System (ADS)

Sassi, Fabrizio; Siskind, David E.; Tate, Jennifer L.; Liu, Han-Li; Randall, Cora E.

2018-04-01

We investigate the benefit of high-altitude nudging in simulations of the structure and short-term variability of the upper mesosphere and lower thermosphere (UMLT) dynamical meteorology during boreal winter, specifically around the time of the January 2009 sudden stratospheric warming. We compare simulations using the Specified Dynamics, Whole Atmosphere Community Climate Model, extended version, nudged using atmospheric specifications generated by the Navy Operational Global Atmospheric Prediction System, Advanced Level Physics High Altitude. Two sets of simulations are carried out: one uses nudging over a vertical domain from 0 to 90 km; the other uses nudging over a vertical domain from 0 to 50 km. The dynamical behavior is diagnosed from ensemble mean and standard deviation of winds, temperature, and zonal accelerations due to resolved and parameterized waves. We show that the dynamical behavior of the UMLT is quite different in the two experiments, with prominent differences in the structure and variability of constituent transport. We compare the results of our numerical experiments to observations of carbon monoxide by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer to show that the high-altitude nudging is capable of reproducing with high fidelity the observed variability, and traveling planetary waves are a crucial component of the dynamics. The results of this study indicate that to capture the key physical processes that affect short-term variability (defined as the atmospheric behavior within about 10 days of a stratospheric warming) in the UMLT, specification of the atmospheric state in the stratosphere alone is not sufficient, and upper atmospheric specifications are needed.
Multi-species analysis of ion distributions at Mars

NASA Astrophysics Data System (ADS)

Curry, S.; Liemohn, M. W.; Fang, X.; Ma, Y.; Johnson, B.; Bougher, S. W.; Dong, C.

2012-12-01

This study focuses on using the Mars Test Particle simulation to compare observations with virtual detections of O+, O2+, CO2+, and H+ in an orbital configuration in the Mars space environment. These planetary pick-up ions are formed when the solar wind directly interacts with the neutral atmosphere, causing the ions to be accelerated by the background convective electric field. The subsequent mass loading and ion escape are still the subject of great interest, specifically with respect to which species dominates ion loss from Mars. Modeling efforts and observations have found different results; some conclude that O+ is the most dominant escaping ion while others conclude that O2+ has the larger total loss rate. Furthermore, mass loss might actually favor CO2+ because of its tri-atomic structure. To address this unresolved issue, this study will present velocity space distributions for different species and discuss fluxes and escape rates using different modeling parameters. The simulation will also illustrate individual particle traces, which reveal the origin and trajectories of the different ion species. Finally, results from different solar conditions will be presented with respect to ion fluxes and energies as well as overall escape in order to robustly describe the physical processes controlling planetary ion distributions and atmospheric escape.
Exploring the climate of Proxima B with the Met Office Unified Model

NASA Astrophysics Data System (ADS)

Boutle, Ian A.; Mayne, Nathan J.; Drummond, Benjamin; Manners, James; Goyal, Jayesh; Hugo Lambert, F.; Acreman, David M.; Earnshaw, Paul D.

2017-05-01

We present results of simulations of the climate of the newly discovered planet Proxima Centauri B, performed using the Met Office Unified Model (UM). We examine the responses of both an "Earth-like" atmosphere and simplified nitrogen and trace carbon dioxide atmosphere to the radiation likely received by Proxima Centauri B. Additionally, we explore the effects of orbital eccentricity on the planetary conditions using a range of eccentricities guided by the observational constraints. Overall, our results are in agreement with previous studies in suggesting Proxima Centauri B may well have surface temperatures conducive to the presence of liquid water. Moreover, we have expanded the parameter regime over which the planet may support liquid water to higher values of eccentricity (≳0.1) and lower incident fluxes (881.7 W m-2) than previous work. This increased parameter space arises because of the low sensitivity of the planet to changes in stellar flux, a consequence of the stellar spectrum and orbital configuration. However, we also find interesting differences from previous simulations, such as cooler mean surface temperatures for the tidally-locked case. Finally, we have produced high-resolution planetary emission and reflectance spectra, and highlight signatures of gases vital to the evolution of complex life on Earth (oxygen, ozone and carbon dioxide).
A New Eddy Dissipation Rate Formulation for the Terminal Area PBL Prediction System(TAPPS)

NASA Technical Reports Server (NTRS)

Charney, Joseph J.; Kaplan, Michael L.; Lin, Yuh-Lang; Pfeiffer, Karl D.

2000-01-01

The TAPPS employs the MASS model to produce mesoscale atmospheric simulations in support of the Wake Vortex project at Dallas Fort-Worth International Airport (DFW). A post-processing scheme uses the simulated three-dimensional atmospheric characteristics in the planetary boundary layer (PBL) to calculate the turbulence quantities most important to the dissipation of vortices: turbulent kinetic energy and eddy dissipation rate. TAPPS will ultimately be employed to enhance terminal area productivity by providing weather forecasts for the Aircraft Vortex Spacing System (AVOSS). The post-processing scheme utilizes experimental data and similarity theory to determine the turbulence quantities from the simulated horizontal wind field and stability characteristics of the atmosphere. Characteristic PBL quantities important to these calculations are determined based on formulations from the Blackadar PBL parameterization, which is regularly employed in the MASS model to account for PBL processes in mesoscale simulations. The TAPPS forecasts are verified against high-resolution observations of the horizontal winds at DFW. Statistical assessments of the error in the wind forecasts suggest that TAPPS captures the essential features of the horizontal winds with considerable skill. Additionally, the turbulence quantities produced by the post-processor are shown to compare favorably with corresponding tower observations.
An abstract model for radiative transfer in an atmosphere with reflection by the planetary surface

NASA Astrophysics Data System (ADS)

Greenberg, W.; van der Mee, C. V. M.

1985-07-01

A Hilbert-space model is developed that applies to radiative transfer in a homogeneous, plane-parallel planetary atmosphere. Reflection and absorption by the planetary surface are taken into account by imposing a reflective boundary condition. The existence and uniqueness of the solution of this boundary value problem are established by proving the invertibility of a scattering operator using the Fredholm alternative.
Problem of photochemical equilibrium of ozone in planetary atmospheres: Ozone distribution in the lower atmosphere of Mars

NASA Technical Reports Server (NTRS)

Grams, G. W.; SHARDANAND

1972-01-01

The inherent errors of applying terrestrial atmospheric ozone distribution studies to the atmosphere of other planets are discussed. Limitations associated with some of the earlier treatments of photochemical equilibrium distributions of ozone in planetary atmospheres are described. A technique having more universal application is presented. Ozone concentration profiles for the Martian atmosphere based on the results of the Mariner 4 radio occultation experiment and the more recent results with Mariner 6 and Mariner 7 have been calculated using this approach.
Survival and germinability of Bacillus subtilis spores exposed to simulated Mars solar radiation: implications for life detection and planetary protection.

PubMed

Tauscher, Courtney; Schuerger, Andrew C; Nicholson, Wayne L

2006-08-01

Bacterial spores have been considered as microbial life that could survive interplanetary transport by natural impact processes or human spaceflight activity. Deposition of terrestrial microbes or their biosignature molecules onto the surface of Mars could negatively impact life detection experiments and planetary protection measures. Simulated Mars solar radiation, particularly the ultraviolet component, has been shown to reduce spore viability, but its effect on spore germination and resulting production of biosignature molecules has not been explored. We examined the survival and germinability of Bacillus subtilis spores exposed to simulated martian conditions that include solar radiation. Spores of B. subtilis that contain luciferase resulting from expression of an sspB-luxAB gene fusion were deposited on aluminum coupons to simulate deposition on spacecraft surfaces and exposed to simulated Mars atmosphere and solar radiation. The equivalent of 42 min of simulated Mars solar radiation exposure reduced spore viability by nearly 3 logs, while germination-induced bioluminescence, a measure of germination metabolism, was reduced by less than 1 log. The data indicate that spores can retain the potential to initiate germination-associated metabolic processes and produce biological signature molecules after being rendered nonviable by exposure to Mars solar radiation.
Stellar Ablation of Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Moore, Thomas E.; Horwitz, J. L.

2007-01-01

We review observations and theories of the solar ablation of planetary atmospheres, focusing on the terrestrial case where a large magnetosphere holds off the solar wind, so that there is little direct atmospheric impact, but also couples the solar wind electromagnetically to the auroral zones. We consider the photothermal escape flows known as the polar wind or refilling flows, the enhanced mass flux escape flows that result from localized solar wind energy dissipation in the auroral zones, and the resultant enhanced neutral atom escape flows. We term these latter two escape flows the "auroral wind." We review observations and theories of the heating and acceleration of auroral winds, including energy inputs from precipitating particles, electromagnetic energy flux at magnetohydrodynamic and plasma wave frequencies, and acceleration by parallel electric fields and by convection pickup processes also known as "centrifugal acceleration." We consider also the global circulation of ionospheric plasmas within the magnetosphere, their participation in magnetospheric disturbances as absorbers of momentum and energy, and their ultimate loss from the magnetosphere into the downstream solar wind, loading reconnection processes that occur at high altitudes near the magnetospheric boundaries. We consider the role of planetary magnetization and the accumulating evidence of stellar ablation of extrasolar planetary atmospheres. Finally, we suggest and discuss future needs for both the theory and observation of the planetary ionospheres and their role in solar wind interactions, to achieve the generality required for a predictive science of the coupling of stellar and planetary atmospheres over the full range of possible conditions.
Space Dust Collisions as a Planetary Escape Mechanism.

PubMed

Berera, Arjun

2017-12-01

It is observed that hypervelocity space dust, which is continuously bombarding Earth, creates immense momentum flows in the atmosphere. Some of this fast space dust inevitably will interact with the atmospheric system, transferring energy and moving particles around, with various possible consequences. This paper examines, with supporting estimates, the possibility that by way of collisions the Earth-grazing component of space dust can facilitate planetary escape of atmospheric particles, whether they are atoms and molecules that form the atmosphere or larger-sized particles. An interesting outcome of this collision scenario is that a variety of particles that contain telltale signs of Earth's organic story, including microbial life and life-essential molecules, may be "afloat" in Earth's atmosphere. The present study assesses the capability of this space dust collision mechanism to propel some of these biological constituents into space. Key Words: Hypervelocity space dust-Collision-Planetary escape-Atmospheric constituents-Microbial life. Astrobiology 17, 1274-1282.

Understanding Microbial Contributions to Planetary Atmosphere

NASA Technical Reports Server (NTRS)

DesMarais, David J.

2000-01-01

Should our search of distant, extrasolar planetary atmospheres encounter evidence of life, that evidence will most likely be the gaseous products of microorganisms. Our biosphere was exclusively microbial for over 80 percent of its history and, even today, microbes strongly influence atmospheric composition. Life's greatest environmental impact arises from its capacity for harvesting energy and creating organic matter. Microorganisms catalyze the equilibration of C, S and transition metal species at temperatures where such reactions can be very slow in the absence of life. Sunlight has been harvested through photosynthesis to create enormous energy reservoirs that exist in the form of coexisting reservoirs of reduced, organic C and S stored in Earth's crust, and highly oxidized species (oxygen, sulfate and ferric iron) stored in the crust, oceans and atmosphere. Our civilization taps that storehouse of energy by burning fossil fuels. As astrobiologists, we identify the chemical consequences of distant biospheres as expressed in the atmospheres of their planets. Our approach must recognize that planets, biospheres and atmospheres evolve and change. For example, a tectonically more active early Earth hosted a thermophilic, non-photosynthetic biosphere and a mildly reducing, carbon dioxide-rich and oxygen-poor atmosphere. Microorganisms acquired energy by consuming hydrogen and sulfide and producing a broad array of reduced C and S gases, most notably, methane. Later, diverse types of bacterial photosynthesis developed that enhanced productivity but were incapable of splitting water to produce oxygen. Later, but still prior to 2.6 billion years ago, oxygenic photosynthesis developed. We can expect to encounter distant biospheres that represent various stages of evolution and that coexist with atmospheres ranging from mildly reducing to oxidizing compositions. Accordinaly, we must be prepared to interpret a broad range of atmospheric compositions, all containing signatures of life. Remarkably little is known about the composition of our own earlier atmosphere, particularly prior to the rise of oxygen levels some 2.0 to 2.2 billion years ago. Thus, field and laboratory observations and theoretical simulations should be conducted to examine the relationships between the structure and function of microbial ecosystems and their gaseous products. Ecosystems that are analogs of our ancient biosphere (e.g., based upon chemosynthesis or non-oxygenic photosynthesis, thermophilic and subsurface communities, etc.) should be included. Because key environmental parameters such as temperature and levels of hydrogen, carbon dioxide and oxygen varied during planetary evolution, their consequences for microbial ecosystems should be explored.
Terrestrial Planets: Comparative Planetology

NASA Technical Reports Server (NTRS)

1985-01-01

Papers were presented at the 47th Annual Meteoritical Society Meeting on the Comparative planetology of Terrestrial Planets. Subject matter explored concerning terrestrial planets includes: interrelationships among planets; plaentary evolution; planetary structure; planetary composition; planetary Atmospheres; noble gases in meteorites; and planetary magnetic fields.
Effects of the seasonal cycle on superrotation in planetary atmospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, Jonathan L.; Vallis, Geoffrey K.; Potter, Samuel F.

2014-05-20

The dynamics of dry atmospheric general circulation model simulations forced by seasonally varying Newtonian relaxation are explored over a wide range of two control parameters and are compared with the large-scale circulation of Earth, Mars, and Titan in their relevant parameter regimes. Of the parameters that govern the behavior of the system, the thermal Rossby number (Ro) has previously been found to be important in governing the spontaneous transition from an Earth-like climatology of winds to a superrotating one with prograde equatorial winds, in the absence of a seasonal cycle. This case is somewhat unrealistic as it applies only ifmore » the planet has zero obliquity or if surface thermal inertia is very large. While Venus has nearly vanishing obliquity, Earth, Mars, and Titan (Saturn) all have obliquities of ∼25° and varying degrees of seasonality due to their differing thermal inertias and orbital periods. Motivated by this, we introduce a time-dependent Newtonian cooling to drive a seasonal cycle using idealized model forcing, and we define a second control parameter that mimics non-dimensional thermal inertia of planetary surfaces. We then perform and analyze simulations across the parameter range bracketed by Earth-like and Titan-like regimes, assess the impact on the spontaneous transition to superrotation, and compare Earth, Mars, and Titan to the model simulations in the relevant parameter regime. We find that a large seasonal cycle (small thermal inertia) prevents model atmospheres with large thermal Rossby numbers from developing superrotation by the influences of (1) cross-equatorial momentum advection by the Hadley circulation and (2) hemispherically asymmetric zonal-mean zonal winds that suppress instabilities leading to equatorial momentum convergence. We also demonstrate that baroclinic instabilities must be sufficiently weak to allow superrotation to develop. In the relevant parameter regimes, our seasonal model simulations compare favorably to large-scale, seasonal phenomena observed on Earth and Mars. In the Titan-like regime the seasonal cycle in our model acts to prevent superrotation from developing, and it is necessary to increase the value of a third parameter—the atmospheric Newtonian cooling time—to achieve a superrotating climatology.« less
Photochemical Formation of Aerosol in Planetary Atmospheres: Photon and Water Mediated Chemistry of SO_2

NASA Astrophysics Data System (ADS)

Kroll, Jay A.; Donaldson, D. J.; Vaida, Veronica

2016-06-01

Sulfur compounds have been observed in a number of planetary atmospheres throughout our solar system. Our current understanding of sulfur chemistry explains much of what we observe in Earth's atmosphere. However, several discrepancies between modeling and observations of the Venusian atmosphere show there are still problems in our fundamental understanding of sulfur chemistry. This is of particular concern due to the important role sulfur compounds play in the formation of aerosols, which have a direct impact on planetary climates, including Earth's. We investigate the role of water complexes in the hydration of sulfur oxides and dehydration of sulfur acids and will present spectroscopic studies to document such effects. I will present recent work investigating mixtures of SO_2 and water that generate large quantities of aerosol when irradiated with solar UV light, even in the absence of traditional OH chemistry. I will discuss a proposed mechanism for the formation of sulfurous acid (H_2SO_3) and present recent experimental work that supports this proposed mechanism. Additionally, the implications that photon-induced hydration of SO_2 has for aerosol formation in the atmosphere of earth as well as other planetary atmospheres will be discussed.
Planetary Wind Determination by Doppler Tracking of a Small Entry Probe Network

NASA Astrophysics Data System (ADS)

Atkinson, D. H.; Asmar, S.; Lazio, J.; Preston, R. A.

2017-12-01

To understand the origin and chemical/dynamical evolution of planetary atmospheres, measurements of atmospheric chemistries and processes including dynamics are needed. In situ measurements of planetary winds have been demonstrated on multiple occasions, including the Pioneer multiprobe and Venera missions to Venus, and the Galileo/Jupiter and Huygens/Titan probes. However, with the exception of Pioneer Venus, the retrieval of the zonal (east-west) wind profile has been limited to a single atmospheric slice. significantly improved understanding of the global dynamics requires sampling of multiple latitudes, times of day, and seasons. Simultaneous tracking of a small network of probes would enable measurements of spatially distributed winds providing a substantially improved characterization of a planet's global atmospheric circulation. Careful selection of descent locations would provide wind measurements at latitudes receiving different solar insolations, longitudes reflecting different times of day, and different seasons if both hemispheres are targeted. Doppler wind retrievals are limited by the stability of the probe and carrier spacecraft clocks, and must be equipped with an ultrastable oscillator, accelerometers for reconstructing the probe entry trajectory, and pressure / temperature sensors for determination of descent speed. A probe were equipped with both absolute and dynamic pressure sensors can measure planet center-relative and atmosphere-relative descent speeds, enabling the measurement of vertical winds from convection or atmospheric waves. Possible ambiguities arising from the assumption of no north-south winds could be removed if the probe were simultaneously tracked from the carrier spacecraft as well as from the Earth or a second spacecraft. The global circulation of an atmosphere comprising waves and flows that vary with location and depth is inherently tied to the thermal, chemical, and energy structure of the atmosphere. Wind measurements along a single vertical atmospheric slice cannot adequately represent the overall dynamical properties of the atmosphere. To more completely characterize the dynamical structure of a planetary atmosphere, it is proposed that future in situ planetary missions include a network of small probes dedicated to wind measurements.
Statistical Similarities Between WSA-ENLIL+Cone Model and MAVEN in Situ Observations From November 2014 to March 2016

NASA Astrophysics Data System (ADS)

Lentz, C. L.; Baker, D. N.; Jaynes, A. N.; Dewey, R. M.; Lee, C. O.; Halekas, J. S.; Brain, D. A.

2018-02-01

Normal solar wind flows and intense solar transient events interact directly with the upper Martian atmosphere due to the absence of an intrinsic global planetary magnetic field. Since the launch of the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, there are now new means to directly observe solar wind parameters at the planet's orbital location for limited time spans. Due to MAVEN's highly elliptical orbit, in situ measurements cannot be taken while MAVEN is inside Mars' magnetosheath. To model solar wind conditions during these atmospheric and magnetospheric passages, this research project utilized the solar wind forecasting capabilities of the WSA-ENLIL+Cone model. The model was used to simulate solar wind parameters that included magnetic field magnitude, plasma particle density, dynamic pressure, proton temperature, and velocity during a four Carrington rotation-long segment. An additional simulation that lasted 18 Carrington rotations was then conducted. The precision of each simulation was examined for intervals when MAVEN was in the upstream solar wind, that is, with no exospheric or magnetospheric phenomena altering in situ measurements. It was determined that generalized, extensive simulations have comparable prediction capabilities as shorter, more comprehensive simulations. Generally, this study aimed to quantify the loss of detail in long-term simulations and to determine if extended simulations can provide accurate, continuous upstream solar wind conditions when there is a lack of in situ measurements.
The GEISA Spectroscopic Database System in its latest Edition

NASA Astrophysics Data System (ADS)

Jacquinet-Husson, N.; Crépeau, L.; Capelle, V.; Scott, N. A.; Armante, R.; Chédin, A.

2009-04-01

GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Spectroscopic Information)[1] is a computer-accessible spectroscopic database system, designed to facilitate accurate forward planetary radiative transfer calculations using a line-by-line and layer-by-layer approach. It was initiated in 1976. Currently, GEISA is involved in activities related to the assessment of the capabilities of IASI (Infrared Atmospheric Sounding Interferometer on board the METOP European satellite -http://earth-sciences.cnes.fr/IASI/)) through the GEISA/IASI database[2] derived from GEISA. Since the Metop (http://www.eumetsat.int) launch (October 19th 2006), GEISA/IASI is the reference spectroscopic database for the validation of the level-1 IASI data, using the 4A radiative transfer model[3] (4A/LMD http://ara.lmd.polytechnique.fr; 4A/OP co-developed by LMD and Noveltis with the support of CNES). Also, GEISA is involved in planetary research, i.e.: modelling of Titan's atmosphere, in the comparison with observations performed by Voyager: http://voyager.jpl.nasa.gov/, or by ground-based telescopes, and by the instruments on board the Cassini-Huygens mission: http://www.esa.int/SPECIALS/Cassini-Huygens/index.html. The updated 2008 edition of GEISA (GEISA-08), a system comprising three independent sub-databases devoted, respectively, to line transition parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols, will be described. Spectroscopic parameters quality requirement will be discussed in the context of comparisons between observed or simulated Earth's and other planetary atmosphere spectra. GEISA is implemented on the CNES/CNRS Ether Products and Services Centre WEB site (http://ether.ipsl.jussieu.fr), where all archived spectroscopic data can be handled through general and user friendly associated management software facilities. More than 350 researchers are registered for on line use of GEISA. Refs: 1. Jacquinet-Husson N., N.A. Scott, A. Chédin,L. Crépeau, R. Armante, V. Capelle, J. Orphal, A. Coustenis, C. Boonne, N. Poulet-Crovisier, et al. THE GEISA SPECTROSCOPIC DATABASE: Current and future archive for Earth and planetary atmosphere studies. JQSRT, 109, 1043-1059, 2008 2. Jacquinet-Husson N., N.A. Scott, A. Chédin, K. Garceran, R. Armante, et al. The 2003 edition of the GEISA/IASI spectroscopic database. JQSRT, 95, 429-67, 2005. 3. Scott, N.A. and A. Chedin, 1981: A fast line-by-line method for atmospheric absorption computations: The Automatized Atmospheric Absorption Atlas. J. Appl. Meteor., 20,556-564.
Spin of Planetary Probes in Atmospheric Flight

NASA Astrophysics Data System (ADS)

Lorenz, R. D.

Probes that enter planetary atmospheres are often spun during entry or descent for a variety of reasons. Their spin rate histories are influenced by often subtle effects. The spin requirements, control methods and flight experience from planetary and earth entry missions are reviewed. An interaction of the probe aerodynamic wake with a drogue parachute, observed in Gemini wind tunnel tests, is discussed in connection with the anomalous spin behaviour of the Huygens probe.
Charge exchange, ENAs and the loss of planetary ions at Mars

NASA Astrophysics Data System (ADS)

Kallio, E.; Janhunen, P.; Säles, T.

Neither Mars nor Venus has a strong global intrinsic magnetic field and therefore the solar wind can flow close to the planets in high neutral density regions. Because of the formed direct interaction between the atmosphere/exosphere and the solar wind, the ionized atmospheric neutrals can be picked up by the solar wind. Charge exchange between solar wind protons and planetary neutrals, instead, produce energetic neutral hydrogen atoms (H-ENA) which are the manifestation of the direct interaction between the solar wind and planetary neutrals. Picked-up planetary O+ ions in turn form energetic neutral oxygen atoms (O-ENA) via charge exchange process. The ion escape, H-ENAs, O-ENAs and electrons will be investigated at Mars and Venus by two identical instruments: ASPERA-3 on MarsExpress (measurements started in Jan. 2004) and ASPERA-4 on VenusExpress (2006). We present a self-consistent, three-dimensional quasi-neutral hybrid (ions are particles, electrons a fluid) simulation to study Mars/Venus-solar wind interaction in general and ASPERA-3/4 measurements in particular. Our model includes three ion species (H+, O+, O2+), and contains charge exchange, ion-neutral and chemical reactions. We show results of quasi-neutral hybrid model runs that we have used to study the escape of planetary ions, the effects of planetary ions on the Martian plasma environment and the production and properties of fast hydrogen(H) and oxygen(O) ENAs near Mars. We also compare these hydrogen ENA images with the hydrogen ENA images that has been derived from an empirical flow model by line-of-sight integration. The advantage of the analytical gas dynamic like flow model is that it is computationally so fast that it provides a possibility to perform an ENA inversion, that is, to derive global plasma parameters from the measured ENA image.
Geophysical Fluid Dynamics Outreach Films

NASA Astrophysics Data System (ADS)

Aurnou, J. M.; Schwarz, J. W.; Noguez, G.

2012-12-01

Here we will present high definition films of laboratory experiments demonstrating basic fluid motions similar to those occurring in atmospheres and oceans. In these experiments, we use water to simulate the fluid dynamics of both the liquid (oceans) and gaseous (atmospheric) envelopes. To simulate the spinning of the earth, we carry out the experiments on a rotating table. For each experiment, we begin by looking at our system first without the effects of rotation. Then, we include rotation to see how the behavior of the fluid changes due to the Coriolis accelerations. Our hope is that by viewing these experiments one will develop a sense for how fluids behave both in rotating and non-rotating systems. By noting the differences between the experiments, it should then be possible to establish a basis to think about large-scale fluid motions that exist in Earth's oceans and atmospheres as well as on planets other than Earth.Plan view image of vortices in a rotating tank of fluid. Movies of such flows make accessible the often difficult to comprehend fluid dynamical processes that occur in planetary atmospheres and oceans.
Planetary data analysis and display system: A version of PC-McIDAS

NASA Technical Reports Server (NTRS)

Limaye, Sanjay S.; Sromovsky, L. A.; Saunders, R. S.; Martin, Michael

1993-01-01

We propose to develop a system for access and analysis of planetary data from past and future space missions based on an existing system, the PC-McIDAS workstation. This system is now in use in the atmospheric science community for access to meteorological satellite and conventional weather data. The proposed system would be usable not only by planetary atmospheric researchers but also by the planetary geologic community. By providing the critical tools of an efficient system architecture, newer applications and customized user interfaces can be added by the end user within such a system.
Greenhouse effect in planetary atmospheres caused by molecular symmetry breaking in intermolecular interactions

NASA Astrophysics Data System (ADS)

Vigasin, A. A.; Mokhov, I. I.

2017-03-01

It is believed that the greenhouse effect is related to the parameters of absorption spectra of polyatomic molecules, usually trace gases, in planetary atmospheres. The main components of all known atmospheres of celestial bodies are symmetrical molecules that do not possess the dipole-allowed purely rotational (and in the case of diatomic molecules, vibrational-rotational) absorption spectrum. Upon increased pressure, a weak absorption appears, induced by intermolecular interaction, which can lead to a greenhouse effect. The contribution of the induced absorption in radiative forcing of a dense atmosphere may amount to a few or even tens of W/m2. In conditions typical for the atmospheres of terrestrial planets (including paleoatmospheres), the collision-induced absorption and associated greenhouse effect may lead to an increase in surface temperature above the freezing point of water. There is a correlation between the temperature of an atmosphere and the intermolecular bonding energy of gases that dominate in planetary atmospheres of the Solar System.
The circulation pattern and day-night heat transport in the atmosphere of a synchronously rotating aquaplanet: Dependence on planetary rotation rate

NASA Astrophysics Data System (ADS)

Noda, S.; Ishiwatari, M.; Nakajima, K.; Takahashi, Y. O.; Takehiro, S.; Onishi, M.; Hashimoto, G. L.; Kuramoto, K.; Hayashi, Y.-Y.

2017-01-01

In order to investigate a possible variety of atmospheric states realized on a synchronously rotating aquaplanet, an experiment studying the impact of planetary rotation rate is performed using an atmospheric general circulation model (GCM) with simplified hydrological and radiative processes. The entire planetary surface is covered with a swamp ocean. The value of planetary rotation rate is varied from zero to the Earth's, while other parameters such as planetary radius, mean molecular weight and total mass of atmospheric dry components, and solar constant are set to the present Earth's values. The integration results show that the atmosphere reaches statistically equilibrium states for all runs; none of the calculated cases exemplifies the runaway greenhouse state. The circulation patterns obtained are classified into four types: Type-I characterized by the dominance of a day-night thermally direct circulation, Type-II characterized by a zonal wave number one resonant Rossby wave over a meridionally broad westerly jet on the equator, Type-III characterized by a long time scale north-south asymmetric variation, and Type-IV characterized by a pair of mid-latitude westerly jets. With the increase of planetary rotation rate, the circulation evolves from Type-I to Type-II and then to Type-III gradually and smoothly, whereas the change from Type-III to Type-IV is abrupt and discontinuous. Over a finite range of planetary rotation rate, both Types-III and -IV emerge as statistically steady states, constituting multiple equilibria. In spite of the substantial changes in circulation, the net energy transport from the day side to the night side remains almost insensitive to planetary rotation rate, although the partition into dry static energy and latent heat energy transports changes. The reason for this notable insensitivity is that the outgoing longwave radiation over the broad area of the day side is constrained by the radiation limit of a moist atmosphere, so that the transport to the night side, which is determined as the difference between the incoming solar radiation and the radiation limit, cannot change greatly.
A Population Study of Gaseous Exoplanets

NASA Astrophysics Data System (ADS)

Tsiaras, A.; Waldmann, I. P.; Zingales, T.; Rocchetto, M.; Morello, G.; Damiano, M.; Karpouzas, K.; Tinetti, G.; McKemmish, L. K.; Tennyson, J.; Yurchenko, S. N.

2018-04-01

We present here the analysis of 30 gaseous extrasolar planets, with temperatures between 600 and 2400 K and radii between 0.35 and 1.9 R Jup. The quality of the HST/WFC3 spatially scanned data combined with our specialized analysis tools allow us to study the largest and most self-consistent sample of exoplanetary transmission spectra to date and examine the collective behavior of warm and hot gaseous planets rather than isolated case studies. We define a new metric, the Atmospheric Detectability Index (ADI) to evaluate the statistical significance of an atmospheric detection and find statistically significant atmospheres in around 16 planets out of the 30 analyzed. For most of the Jupiters in our sample, we find the detectability of their atmospheres to be dependent on the planetary radius but not on the planetary mass. This indicates that planetary gravity plays a secondary role in the state of gaseous planetary atmospheres. We detect the presence of water vapour in all of the statistically detectable atmospheres, and we cannot rule out its presence in the atmospheres of the others. In addition, TiO and/or VO signatures are detected with 4σ confidence in WASP-76 b, and they are most likely present in WASP-121 b. We find no correlation between expected signal-to-noise and atmospheric detectability for most targets. This has important implications for future large-scale surveys.
Generic aerocapture atmospheric entry study, volume 1

NASA Technical Reports Server (NTRS)

1980-01-01

An atmospheric entry study to fine a generic aerocapture vehicle capable of missions to Mars, Saturn, and Uranus is reported. A single external geometry was developed through atmospheric entry simulations. Aerocapture is a system design concept which uses an aerodynamically controlled atmospheric entry to provide the necessary velocity depletion to capture payloads into planetary orbit. Design concepts are presented which provide the control accuracy required while giving thermal protection for the mission payload. The system design concepts consist of the following elements: (1) an extendable biconic aerodynamic configuration with lift to drag ratio between 1.0 and 2.0; (2) roll control system concepts to control aerodynamic lift and disturbance torques; (3) aeroshell design concepts capable of meeting dynamic pressure loads during aerocapture; and (4) entry thermal protection system design concepts to meet thermodynamic loads during aerocapture.
Propagation of Stationary Planetary Waves in the Upper Atmosphere under Different Solar Activity

NASA Astrophysics Data System (ADS)

Koval, A. V.; Gavrilov, N. M.; Pogoreltsev, A. I.; Shevchuk, N. O.

2018-03-01

Numerical modeling of changes in the zonal circulation and amplitudes of stationary planetary waves are performed with an accounting for the impact of solar activity variations on the thermosphere. A thermospheric version of the Middle/Upper Atmosphere Model (MUAM) is used to calculate the circulation in the middle and upper atmosphere at altitudes up to 300 km from the Earth's surface. Different values of the solar radio emission flux in the thermosphere are specified at a wavelength of 10.7 cm to take into account the solar activity variations. The ionospheric conductivities and their variations in latitude, longitude, and time are taken into account. The calculations are done for the January-February period and the conditions of low, medium, and high solar activity. It was shown that, during high-activity periods, the zonal wind velocities increases at altitudes exceeding 150 km and decreases in the lower layers. The amplitudes of planetary waves at high solar activity with respect to the altitude above 120 km or below 100 km, respectively, are smaller or larger than those at low activity. These differences correspond to the calculated changes in the refractive index of the atmosphere for stationary planetary waves and the Eliassen-Palm flux. Changes in the conditions for the propagation and reflection of stationary planetary waves in the thermosphere may influence the variations in their amplitudes and the atmospheric circulation, including the lower altitudes of the middle atmosphere.
Atmospheric dynamics and habitability range in Earth-like aquaplanets obliquity simulations

NASA Astrophysics Data System (ADS)

Nowajewski, Priscilla; Rojas, M.; Rojo, P.; Kimeswenger, S.

2018-05-01

We present the evolution of the atmospheric variables that affect planetary climate by increasing the obliquity by using a general circulation model (PlaSim) coupled to a slab ocean with mixed layer flux correction. We increase the obliquity between 30° and 90° in 16 aquaplanets with liquid sea surface and perform the simulation allowing the sea ice cover formation to be a consequence of its atmospheric dynamics. Insolation is maintained constant in each experiment, but changing the obliquity affects the radiation budget and the large scale circulation. Earth-like atmospheric dynamics is observed for planets with obliquity under 54°. Above this value, the latitudinal temperature gradient is reversed giving place to a new regime of jet streams, affecting the shape of Hadley and Ferrel cells and changing the position of the InterTropical Convergence Zone. As humidity and high temperatures determine Earth's habitability, we introduce the wet bulb temperature as an atmospheric index of habitability for Earth-like aquaplanets with above freezing temperatures. The aquaplanets are habitable all year round at all latitudes for values under 54°; above this value habitability decreases toward the poles due to high temperatures.
Airborne measurements of solar and planetary near ultraviolet radiation during the NASA/ESA CV-900 spacelab simulation

NASA Technical Reports Server (NTRS)

Sivjee, G. G.

1977-01-01

Results from a comparative study of the feasibility of employing experiment operators on the space shuttle to acquire scientifically worthwhile data are presented. The experiments performed during these tests included spectral observations of the Sun and Venus in the near ultraviolet region. The solar measurements were analyzed to determine ozone abundance in the terrestrial atmosphere. Using a detailed spectral matching technique to compare airborne solar UV measurements with synthetic spectral profiles of sunlight, it is deduced that in winter the total atmospheric ozone abundance is about 0.33 atm/cm at midlatitudes in the northern hemisphere.
INFLUENCE OF STELLAR FLARES ON THE CHEMICAL COMPOSITION OF EXOPLANETS AND SPECTRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venot, Olivia; Decin, Leen; Rocchetto, Marco

More than three thousand exoplanets have been detected so far, and more and more spectroscopic observations of exoplanets are performed. Future instruments ( James Webb Space Telescope ( JWST ), E-ELT, PLATO, Ariel, etc.,) are eagerly awaited, as they will be able to provide spectroscopic data with greater accuracy and sensitivity than what is currently available. This will allow more accurate conclusions to be drawn regarding the chemistry and dynamics of exoplanetary atmospheres, provided that the observational data are carefully processed. One important aspect to consider is temporal stellar atmospheric disturbances that can influence the planetary composition, and hence spectra,more » and potentially can lead to incorrect assumptions about the steady-state atmospheric composition of the planet. In this paper, we focus on perturbations coming from the host star in the form of flare events that significantly increase photon flux impingement on the exoplanets atmosphere. In some cases, particularly for M stars, this sudden increase may last for several hours. We aim to discover to what extent a stellar flare is able to modify the chemical composition of the planetary atmosphere and, therefore, influence the resulting spectra. We use a one-dimensional thermo-photochemical model to study the neutral atmospheric composition of two hypothetical planets located around the star AD Leo. We place the two planets at different distances from the star, which results in effective atmospheric temperatures of 412 and 1303 K. AD Leo is an active star that has already been observed during a flare. Therefore, we use the spectroscopic data from this flare event to simulate the evolution of the chemical composition of the atmospheres of the two hypothetical planets. We compute synthetic spectra to evaluate the implications for observations. The increase in the incoming photon flux affects the chemical abundances of some important species (such as H and NH{sub 3}), down to altitudes associated with an atmospheric pressure of 1 bar, which can lead to variations in planetary spectra (up to 150 ppm) if performed during transit. We find that each exoplanet has a post-flare steady-state composition that is significantly different from the pre-flare steady-state. We predict that these variations could be detectable with both current and future spectroscopic instruments, if sufficiently high signal-to-noise spectra are obtained.« less
Integrated Exoplanet Modeling with the GSFC Exoplanet Modeling & Analysis Center (EMAC)

NASA Astrophysics Data System (ADS)

Mandell, Avi M.; Hostetter, Carl; Pulkkinen, Antti; Domagal-Goldman, Shawn David

2018-01-01

Our ability to characterize the atmospheres of extrasolar planets will be revolutionized by JWST, WFIRST and future ground- and space-based telescopes. In preparation, the exoplanet community must develop an integrated suite of tools with which we can comprehensively predict and analyze observations of exoplanets, in order to characterize the planetary environments and ultimately search them for signs of habitability and life.The GSFC Exoplanet Modeling and Analysis Center (EMAC) will be a web-accessible high-performance computing platform with science support for modelers and software developers to host and integrate their scientific software tools, with the goal of leveraging the scientific contributions from the entire exoplanet community to improve our interpretations of future exoplanet discoveries. Our suite of models will include stellar models, models for star-planet interactions, atmospheric models, planet system science models, telescope models, instrument models, and finally models for retrieving signals from observational data. By integrating this suite of models, the community will be able to self-consistently calculate the emergent spectra from the planet whether from emission, scattering, or in transmission, and use these simulations to model the performance of current and new telescopes and their instrumentation.The EMAC infrastructure will not only provide a repository for planetary and exoplanetary community models, modeling tools and intermodal comparisons, but it will include a "run-on-demand" portal with each software tool hosted on a separate virtual machine. The EMAC system will eventually include a means of running or “checking in” new model simulations that are in accordance with the community-derived standards. Additionally, the results of intermodal comparisons will be used to produce open source publications that quantify the model comparisons and provide an overview of community consensus on model uncertainties on the climates of various planetary targets.

Curie-Montgolfiere Planetary Explorers

NASA Astrophysics Data System (ADS)

Taylor, Chris Y.; Hansen, Jeremiah

2007-01-01

Hot-air balloons, also known as Montgolfiere balloons, powered by heat from radioisotope decay are a potentially useful tool for exploring planetary atmospheres and augmenting the capabilities of other exploration technologies. This paper describes the physical equations and identifies the key engineering parameters that drive radioisotope-powered balloon performance. These parameters include envelope strength-to-weight, envelope thermal conductivity, heater power-to-weight, heater temperature, and balloon shape. The design space for these parameters are shown for varying atmospheric compositions to illustrate the performance needed to build functioning ``Curie-Montgolfiere'' balloons for various planetary atmospheres. Methods to ease the process of Curie-Montgolfiere conceptual design and sizing of are also introduced.
The Blue Dot Workshop: Spectroscopic Search for Life on Extrasolar Planets

NASA Technical Reports Server (NTRS)

Des Marais, David J. (Editor)

1997-01-01

This workshop explored the key questions and challenges associated with detecting life on an extrasolar planet. The final product will be a NASA Conference Publication which includes the abstracts from 21 talks, summaries of key findings, and recommendations for future research. The workshop included sessions on three related topics: the biogeochemistry of biogenic gases in the atmosphere, the chemistry and spectroscopy of planetary atmospheres, and the remote sensing of planetary atmospheres and surfaces. With the observation that planetary formation is probably a common phenomenon, together with the advent of the technical capability to locate and describe extrasolar planets, this research area indeed has an exciting future.
Numerical modeling of planetary-scale waves on Jupiter

NASA Astrophysics Data System (ADS)

Cosentino, Richard; Morales-Juberias, Raul; Simon, Amy

2014-11-01

The atmosphere of Jupiter has multiple alternating east-wind wind jets with different cloud morphologies some of which can be explained by the presence of atmospheric waves. One jet feature observed by Cassini and HST at 30N, called the Jovian Ribbon for its similarity to Saturn's Ribbon, displays chaotic cloud morphology caused by multiple wave components with dominating planetary scale wave-numbers ranging from 13 to 30. Both the cloud morphology and the dominant wave numbers observed change as a function of time and correlate to changes in the jet's speed. The average speed of the westward jet where this Jovian Ribbon is found is small compared to other notable jets that display wave behavior, namely the high velocity eastward jets at 7N (hot spots) and 7S (chevrons). We present the results of numerical simulations that show how attributes like jet speed, location, vertical shear and other background properties of the atmosphere (e.g. static stability) contribute to the development and evolution of wave structures in jets similar to those observed. Additionally, we explore the effects of local convective events and other atmospheric disturbances such as spots, on the morphology of these jets and waves. This work was supported by NASA PATM grant number NNX14AH47G. Computing resources for this research were provided by NMT and Yellowstone at CISL.
Quantifying the Intercontinental and Global Reach and Effects of Pollution

NASA Technical Reports Server (NTRS)

Chatfield, Robert B.; Guo, Zitan

2000-01-01

The Atmospheric Chemistry Modeling Group is participating in an international effort to explore the projected interactions of the atmosphere with biota, human activity, and the natural environment over the next three decades. The group uses computer simulations and statistical analyses to compare theory and observations of the composition of the lower atmosphere. This study of global habitability change is part of a more ambitious activity to understand global habitability. This broad planetary understanding is central to planetary habitability, biomarker detection, and similar aspects of Astrobiology. The group has made highly detailed studies of immense intercontinental plumes that affect the chemistry of the global atmosphere, especially the region below the ozone (O3) layer whose chemical composition defines the conditions for healthy humans and the biosphere. For some decades there has been concern about the pollution from cities and industrial burning and its possible effect in increasing smog ozone, not only in continental regions, but also in plumes that spread downwind. Recently, there has been new concern about another kind of pollution plume. Projections for a greatly expanded aircraft fleet imply that there will be plumes of nitrogen oxides (NO(x)) from jet exhaust in the Northern Hemisphere downwind of major air traffic routes. Both of these are tied to large-scale O3 in the troposphere, where it is toxic to humans and plant tissues.
ALMA observations of Titan's atmospheric chemistry and seasonal variation

NASA Astrophysics Data System (ADS)

Cordiner, Martin

2017-04-01

Titan is the largest moon of Saturn, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Photochemistry in Titan's upper atmosphere results in the production of a wide range of organic molecules, including hydrocarbons, nitriles and aromatics, some of which could be of pre-biotic relevance. Thus, we obtain insights into the possible molecular inventories of primitive (reducing) planetary atmospheres. Titan's atmosphere also provides a unique laboratory for testing our understanding of fundamental processes involving the chemistry and spectroscopy of complex organic molecules. In this talk, results will be presented from our studies using the Atacama Large Millimeter/submillimeter Array (ALMA) during the period 2012-2015, focussing in particular on the detection and mapping of emission from various nitrile species. By combining data from multiple ALMA observations, our spectra have reached an unprecedented sensitivity level, enabling the first spectroscopic detection and mapping of C2H3CN (vinyl cyanide) on Titan. Liquid-phase simulations of Titan's seas indicate that vinyl cyanide molecules could combine to form vesicle membranes (similar to the cells of terrestrial biology), and the astrobiological implications of this discovery will be discussed. Furthermore, ALMA observations provide instantaneous snapshot mapping of Titan's entire Earth-facing hemisphere, for gases inaccessible to previous instruments. Combined with complementary data obtained from the Cassini Saturn orbiter, as well as theoretical models and laboratory studies, our observed, seasonally variable, spatially resolved abundance patterns are capable of providing new insights into photochemical production and transport in primitive planetary atmospheres in the Solar System and beyond.
Voyager Outreach Compilation

NASA Technical Reports Server (NTRS)

1998-01-01

This NASA JPL (Jet Propulsion Laboratory) video presents a collection of the best videos that have been published of the Voyager mission. Computer animation/simulations comprise the largest portion of the video and include outer planetary magnetic fields, outer planetary lunar surfaces, and the Voyager spacecraft trajectory. Voyager visited the four outer planets: Jupiter, Saturn, Uranus, and Neptune. The video contains some live shots of Jupiter (actual), the Earth's moon (from orbit), Saturn (actual), Neptune (actual) and Uranus (actual), but is mainly comprised of computer animations of these planets and their moons. Some of the individual short videos that are compiled are entitled: The Solar System; Voyage to the Outer Planets; A Tour of the Solar System; and the Neptune Encounter. Computerized simulations of Viewing Neptune from Triton, Diving over Neptune to Meet Triton, and Catching Triton in its Retrograde Orbit are included. Several animations of Neptune's atmosphere, rotation and weather features as well as significant discussion of the planet's natural satellites are also presented.
Is there an Alternative for the Huge Impact-Generated Atmosphere?

NASA Astrophysics Data System (ADS)

Gerasimov, M. V.; Dikov, Y. P.; Yakovlev, O. I.; Wlotzka, F.

1998-01-01

The Earth's primordial atmosphere is considered to be the result of impact degassing during planetary accretion. Experiments on the decomposition of a serpentine and calcite during a shock wave loading showed that a rather efficient decomposition could be achieved beginning with the impact velocities that corresponded to escape velocities of a relatively small (about Moon-sized) planetary embryo. During further accumulation of planetary mass, the decomposition of serpentine and carbonates with the release of H2O and CO2 (gases considered to be the main product of impact degassing) into the primordial atmosphere was considered to be complete. The sink rate of H2O and CO2 from the primordial atmosphere was evaluated mainly as atmospheric impact erosion, thermal and EW-driven escape from the atmosphere, hydration and carboniza60n of surface minerals, dissolution of gases in magma ocean, loss of water for oxidation of Fe, etc. The growth of the atmosphere was considered to be a result of source and sink processes during each impact event. The rehydration of 100% of degassed material during an impact is considered to be an end effect when no hydrous atmosphere is formed. But even a small efficiency of impact degassing (the ratio of volatiles that remain in the atmosphere after an impact to the amount delivered by a planetesimal) was calculated to produce an abundant H2O-CO2 atmosphere. During a set of impact simulation experiments we have investigated the chemistry of volatiles and their interaction behavior with condensing silicates at conditions similar to impact vaporization. First, the experiments showed that the gas mixture was not limited only by H20 and CO2 during high-temperature vaporization of silicates, a wide variety of gases were formed, including oxides [SO2, CO2, CO (CO/CO2 approximately 1), H20] and reduced gas components (H2, H2S, CS2, COS, and hydrocarbons). Second, experiments on high-temperature vaporization of mafic and ultramafic rocks and minerals in water and/or CO2 containing atmospheres showed that condensing silicates provide intense trapping of water and/or CO2 during the hot stage of vapor cloud expansion. The amount of water trapped by formation of different hydroxides could be about 10 wt% of silicate mass. The trapping of atmospheric CO2 is proceeded by the formation of carbonates, carbides, hydrocarbons, and elemental C phases. Preliminary results indicate that Ni is also trapped by formation of -NO3, -H2N, and -CN phases. The maximum concentrations of trapped CO2 and N were measured up to 4 wt% and 0.1 wt% respectively. Trapping is efficient even at low partial gas pressures. Impact-induced trapping of atmospheric gases was not accounted for by theoretical models, but it seems to be an efficient process controlling the atmospheric mass. The ratio of volatiles added to the atmosphere after an impact to the amount delivered by a planetesimal can only be positive but sufficiently negative as well. During the impact of a planetesimal analogous to an ordinary chondrite on the growing Earth with a dense atmosphere, the removal of gases from the atmosphere seems to be more probable as a result of release and trapping processes. The capacity of the sink buffer exceeds the whole planetary volatile inventory. The trapping efficiency of gases inside the vapor plume suggests a model for the formation of a primordial atmosphere of moderate density.
MGS Radio Science Measurements of Atmospheric Dynamics on Mars

NASA Astrophysics Data System (ADS)

Hinson, D. P.

2001-12-01

The Sun-synchronous, polar orbit of Mars Global Surveyor (MGS) provides frequent opportunities for radio occultation sounding of the neutral atmosphere. The basic result of each experiment is a profile of pressure and temperature versus planetocentric radius and geopotential. More than 4000 profiles were obtained during the 687-day mapping phase of the mission, and additional observations are underway. These measurements allow detailed characterization of planetary-scale dynamics, including stationary planetary (or Rossby) waves and transient waves produced by instability. For example, both types of dynamics were observed near 67° S during midwinter of the southern hemisphere (Ls=134° --160° ). Planetary waves are the most prominent dynamical feature in this subset of data. At zonal wave number s=1, both the temperature and geopotential fields tilt westward with increasing height, as expected for vertically-propagating planetary waves forced at the surface. The wave-2 structure is more nearly barotropic. The amplitude in geopotential height at Ls=150° increases from ~200 m near the surface to ~700 m at 10 Pa. The corresponding meridional wind speed increases from ~5 m s-1 near the surface to ~20 m s-1 at 10 Pa. Traveling ``baroclinic'' waves also appear intermittently during this interval. The dominant mode has a period of ~2 sols, s=3, and a peak amplitude of ~7 K at 300 Pa. Stong zonal variations in eddy amplitude signal the presence of a possible ``storm zone'' at 150° --330° E longitude. This talk will include other examples of these phenomena as well as comparisons with computer simulations by a Martian general circulation model (MGCM).
Numerical simulation of wave interactions during sudden stratospheric warming

NASA Astrophysics Data System (ADS)

Gavrilov, N. M.; Koval, A. V.; Pogoreltsev, A. I.; Savenkova, E. N.

2017-11-01

Parameterizations of normal atmospheric modes (NAMs) and orographic gravity waves (OGWs) are implemented into the mechanistic general circulation model of the middle and upper atmosphere (MUA). Numerical experiments of sudden stratospheric warming (SSW) events are performed for climatological conditions typical for January and February using meteorological reanalysis data from the UK MET Office in the MUA model averaged over the years 1992-2011 with the easterly phase of quasi-biennial oscillation (QBO). The simulation shows that an increase in the OGW amplitudes occurs at altitudes higher than 30 km in the Northern Hemisphere after SSW. The OGW amplitudes have maximums at altitudes of about 50 km over the North American and European mountain systems before and during SSW, as well as over the Himalayas after SSW. At high latitudes of the Northern Hemisphere, significant (up to 50-70%) variations in the amplitudes of stationary planetary waves (SPWs) are observed during and after the SSW. Westward travelling NAMs have local amplitude maximums not only in the Northern Hemisphere, but also in the Southern Hemisphere, where there are waveguides for the propagation of these modes. Calculated variations of SPW and NAM amplitudes correspond to changes in the mean temperature and wind fields, as well as the Eliassen-Palm flux and atmospheric refractive index for the planetary waves, during SSW. Including OGW thermal and dynamical effects leads to an increase in amplitude (by 30-70%) of almost all SPWs before and during SSW and to a decrease (up to 20-100%) after the SSW at middle and high latitudes of the Northern Hemisphere.
Crossing the Boundaries in Planetary Atmospheres - From Earth to Exoplanets

NASA Technical Reports Server (NTRS)

Simon-Miller, Amy A.; Genio, Anthony Del

2013-01-01

The past decade has been an especially exciting time to study atmospheres, with a renaissance in fundamental studies of Earths general circulation and hydrological cycle, stimulated by questions about past climates and the urgency of projecting the future impacts of humankinds activities. Long-term spacecraft and Earth-based observation of solar system planets have now reinvigorated the study of comparative planetary climatology. The explosion in discoveries of planets outside our solar system has made atmospheric science integral to understanding the diversity of our solar system and the potential habitability of planets outside it. Thus, the AGU Chapman Conference Crossing the Boundaries in Planetary Atmospheres From Earth to Exoplanets, held in Annapolis, MD from June 24-27, 2013 gathered Earth, solar system, and exoplanet scientists to share experiences, insights, and challenges from their individual disciplines, and discuss areas in which thinking broadly might enhance our fundamental understanding of how atmospheres work.
Regarding tracer transport in Mars' winter atmosphere in the presence of nearly stationary, forced planetary waves

NASA Technical Reports Server (NTRS)

Hollingsworth, Jeffrey L.; Haberle, R. M.; Houben, Howard C.

1993-01-01

Large-scale transport of volatiles and condensates on Mars, as well as atmospheric dust, is ultimately driven by the planet's global-scale atmospheric circulation. This circulation arises in part from the so-called mean meridional (Hadley) circulation that is associated with rising/poleward motion in low latitudes and sinking/equatorward motion in middle and high latitudes. Intimately connected to the mean circulation is an eddy-driven component due to large-scale wave activity in the planet's atmosphere. During winter this wave activity arises both from traveling weather systems (i.e., barotropic and baroclinic disturbances) and from 'forced' disturbances (e.g., the thermal tides and surface-forced planetary waves). Possible contributions to the effective (net) transport circulation from forced planetary waves are investigated.
Atmospheric planetary wave response to external forcing

NASA Technical Reports Server (NTRS)

Stevens, D. E.; Reiter, E. R.

1985-01-01

The tools of observational analysis, complex general circulation modeling, and simpler modeling approaches were combined in order to attack problems on the largest spatial scales of the earth's atmosphere. Two different models were developed and applied. The first is a two level, global spectral model which was designed primarily to test the effects of north-south sea surface temperature anomaly (SSTA) gradients between the equatorial and midlatitude north Pacific. The model is nonlinear, contains both radiation and a moisture budget with associated precipitation and surface evaporation, and utilizes a linear balance dynamical framework. Supporting observational analysis of atmospheric planetary waves is briefly summarized. More extensive general circulation models have also been used to consider the problem of the atmosphere's response, especially in the horizontal propagation of planetary scale waves, to SSTA.
Hot planetary winds near a star: dynamics, wind-wind interactions, and observational signatures

NASA Astrophysics Data System (ADS)

Carroll-Nellenback, Jonathan; Frank, Adam; Liu, Baowei; Quillen, Alice C.; Blackman, Eric G.; Dobbs-Dixon, Ian

2017-04-01

Signatures of 'evaporative' winds from exoplanets on short (hot) orbits around their host star have been observed in a number of systems. In this paper, we present global adaptive mesh refinement simulations that track the launching of the winds, their expansion through the circumstellar environment, and their interaction with a stellar wind. We focus on purely hydrodynamic flows including the anisotropy of the wind launching and explore the orbital/fluid dynamics of the resulting flows in detail. In particular, we find that a combination of the tidal and Coriolis forces strongly distorts the planetary 'Parker' wind creating 'up-orbit' and 'down-orbit' streams. We characterize the flows in terms of their orbital elements that change depending on their launch position on the planet. We find that the anisotropy in the atmospheric temperature leads to significant backflow on to the planet. The planetary wind interacts strongly with the stellar wind creating instabilities that may cause eventual deposition of planetary gas on to the star. We present synthetic observations of both transit and absorption line-structure for our simulations. For our initial conditions, we find that the orbiting wind material produces absorption signatures at significant distances from the planet and substantial orbit-to-orbit variability. Lyα absorption shows red- and blueshifted features out to 70 km s-1. Finally, using semi-analytic models we constrain the effect of radiation pressure, given the approximation of uniform stellar absorption.
Planetary quarantine. Space research and technology

NASA Technical Reports Server (NTRS)

1973-01-01

Planetary quarantine strategies for advanced spacecraft consider effects of satellite encounter, Jupiter atmosphere entry, space radiation, and cleaning and decontamination techniques on microbiological growth probability. Analytical restructuring is developed for microbial burden prediction and planetary contamination.
Detection techniques for tenuous planetary atmospheres

NASA Technical Reports Server (NTRS)

Hoenig, S. A.

1972-01-01

The research for the development of new types of detectors for analysis of planetary atmospheres is summarized. Topics discussed include: corona discharge humidity detector, surface catalysis and exo-electron emission, and analysis of soil samples by means of exo-electron emission. A report on the exo-electron emission during heterogeneous catalysis is included.
Planetary Geology: A Teacher's Guide with Activities in Physical and Earth Sciences.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Washington, DC.

This educator's guide discusses planetary geology. Exercises are grouped into five units: (1) introduction to geologic processes; (2) impact cratering activities; (3) planetary atmospheres; (4) planetary surfaces; and (5) geologic mapping. Suggested introductory exercises are noted at the beginning of each exercise. Each activity includes an…
Origin and evolution of planetary atmospheres

NASA Technical Reports Server (NTRS)

Pollack, J. B.; Yung, Y. L.

1980-01-01

The current understanding of the origin and evolution of the atmospheres of solar system objects is reviewed. Physical processes that control this evolution are described in an attempt to develop a set of general principles that can help guide studies of specific objects. Particular emphasis is placed on the planetary and satellite atmospheres of the inner solar system objects; current hypotheses on the origin and evolution of these objects are critically considered.
Remote Thermal IR Spectroscopy of our Solar System

NASA Technical Reports Server (NTRS)

Kostiuk, Theodor; Hewagama, Tilak; Goldstein, Jeffrey; Livengood, Timothy; Fast, Kelly

1999-01-01

Indirect methods to detect extrasolar planets have been successful in identifying a number of stars with companion planets. No direct detection of an extrasolar planet has yet been reported. Spectroscopy in the thermal infrared region provides a potentially powerful approach to detection and characterization of planets and planetary systems. We can use knowledge of our own solar system, its planets and their atmospheres to model spectral characteristics of planets around other stars. Spectra derived from modeling our own solar system seen from an extrasolar perspective can be used to constrain detection strategies, identification of planetary class (terrestrial vs. gaseous) and retrieval of chemical, thermal and dynamical information. Emission from planets in our solar system peaks in the thermal infrared region, approximately 10 - 30 microns, substantially displaced from the maximum of the much brighter solar emission in the visible near 0.5 microns. This fact provides a relatively good contrast ratio to discriminate between stellar (solar) and planetary emission and optimize the delectability of planetary spectra. Important molecular constituents in planetary atmospheres have rotational-vibrational spectra in the thermal infrared region. Spectra from these molecules have been well characterized in the laboratory and studied in the atmospheres of solar system planets from ground-based and space platforms. The best example of such measurements are the studies with Fourier transform spectrometers, the Infrared Interferometer Spectrometers (IRIS), from spacecraft: Earth observed from NIMBUS 8, Mars observed from Mariner 9, and the outer planets observed from Voyager spacecraft. An Earth-like planet is characterized by atmospheric spectra of ozone, carbon dioxide, and water. Terrestrial planets have oxidizing atmospheres which are easily distinguished from reducing atmospheres of gaseous giant planets which lack oxygen-bearing species and are characterized by spectra containing hydrocarbons such as methane and ethane. Spectroscopic information on extrasolar planets thus can permit their classification. Spectra and spectral lines contain information on the temperature structure of the atmosphere. Line and band spectra can be used to identify the molecular constituents and retrieve species abundances, thereby classifying and characterizing the planet. At high enough spectral resolution characteristic planetary atmospheric dynamics and unique phenomena such as failure of local thermodynamic equilibrium can be identified. Dynamically induced effects such as planetary rotation and orbital velocity shift and change the shape of spectral features and must be modeled in detailed spectral studies. We will use our knowledge of the compositional, thermal and dynamical characteristics of planetary atmospheres in our own solar system to model spectra observed remotely on similar planets in extrasolar planetary systems. We will use a detailed radiative transfer and beam integration program developed for the modeling and interpretation of thermal infrared spectra measured from nearby planet planets to generate models of an extra-solar "Earth" and "Jupiter". From these models we will show how key spectral features distinguish between terrestrial and gaseous planets, what information can be obtained with different spectral resolution, what spectral features can be used to search for conditions for biogenic activity, and how dynamics and distance modify the observed spectra. We also will look at unique planetary phenomena such as atmospheric lasing and discuss their utility as probes for detection and identification of planets. Results of such studies will provide information to constrain design for instrumentation needed to directly detect extrasolar planets.
Modeling Io's Sublimation-Driven Atmosphere: Gas Dynamics and Radiation Emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Andrew C.; Goldstein, David B.; Varghese, Philip L.

2008-12-31

Io's sublimation-driven atmosphere is modeled using the direct simulation Monte Carlo method. These rarefied gas dynamics simulations improve upon earlier models by using a three-dimensional domain encompassing the entire planet computed in parallel. The effects of plasma impact heating, planetary rotation, and inhomogeneous surface frost are investigated. Circumplanetary flow is predicted to develop from the warm subsolar region toward the colder night-side. The non-equilibrium thermal structure of the atmosphere, including vibrational and rotational temperatures, is also presented. Io's rotation leads to an asymmetric surface temperature distribution which is found to strengthen circumplanetary flow near the dusk terminator. Plasma heating ismore » found to significantly inflate the atmosphere on both day- and night-sides. The plasma energy flux also causes high temperatures at high altitudes but permits relatively cooler temperatures at low altitudes near the dense subsolar point due to plasma energy depletion. To validate the atmospheric model, a radiative transfer model was developed utilizing the backward Monte Carlo method. The model allows the calculation of the atmospheric radiation from emitting/absorbing and scattering gas using an arbitrary scattering law and an arbitrary surface reflectivity. The model calculates the spectra in the {nu}{sub 2} vibrational band of SO{sub 2} which are then compared to the observational data.« less
Photochemical aerosol formation in planetary atmospheres: A comparison between Pluto and Titan

NASA Astrophysics Data System (ADS)

Lavvas, Panayotis; Strobel, Darrell F.; Lellouch, Emmanuel; Gurwell, Mark A.; Cheng, Andrew F.; Summers, Michael; Gladstone, Randy

2016-10-01

The New Horizons mission observations have revealed us that Pluto's atmosphere is rich in photochemical hazes that extend to high altitudes above its surface [1], apparently similar to those observed in Titan's atmosphere [2].We use detailed models combining photochemistry and microphysics in order to simulate the aerosol formation and growth in Pluto's atmosphere, as performed for Titan's atmosphere [3]. Here we discuss the possible mechanisms leading to the formation of haze particles in Pluto's atmosphere, and we evaluate the contribution of different growth processes (e.g. coagulation vs. condensation) to the resulting particle properties.Moreover we investigate the role of these particles in the radiative balance of Pluto's atmosphere and we compare the resulting particle properties, with those retrieved for Titan's upper atmosphere based on Cassini observations [4]. We discuss the similarities and difference between Pluto's and Titan's aerosols.[1] Gladstone et al., 2016, Science, 351, 6271[2] West et al., 2015, Titan's Haze, in Titan, Interior, Surface, Atmosphere and Space environment, Cambridge University Press[3] Lavvas et al., 2013, PNAS, pnas.1217059110[4] Lavvas et al., 2015, DPS47, id.205.08

Fourier transform spectroscopy for future planetary missions

NASA Astrophysics Data System (ADS)

Brasunas, John C.; Hewagama, Tilak; Kolasinski, John R.; Kostiuk, Theodor

2015-11-01

Thermal-emission infrared spectroscopy is a powerful tool for exploring the composition, temperature structure, and dynamics of planetary atmospheres; and the temperature of solid surfaces. A host of Fourier transform spectrometers (FTS) such as Mariner IRIS, Voyager IRIS, and Cassini CIRS from NASA Goddard have made and continue to make important new discoveries throughout the solar system.Future FTS instruments will have to be more sensitive (when we concentrate on the colder, outer reaches of the solar system), and less massive and less power-hungry as we cope with decreasing resource allotments for future planetary science instruments. With this in mind, NASA Goddard was funded via the Planetary Instrument Definition and Development Progrem (PIDDP) to develop CIRS-lite, a smaller version of the CIRS FTS for future planetary missions. Following the initial validation of CIRS-lite operation in the laboratory, we have been acquiring atmospheric data in the 8-12 micron window at the 1.2 m telescope at the Goddard Geophysical and Astronomical Observatory (GGAO) in Greenbelt, MD. Targets so far have included Earth's atmosphere (in emission, and in absorption against the moon), and Venus.We will present the roadmap for making CIRS-lite a viable candidate for future planetary missions.
Airships for Planetary Exploration

NASA Technical Reports Server (NTRS)

Colozza, Anthony

2004-01-01

The feasibility of utilizing an airship for planetary atmospheric exploration was assessed. The environmental conditions of the planets and moons within our solar system were evaluated to determine their applicability for airship flight. A station-keeping mission of 50 days in length was used as the baseline mission. Airship sizing was performed utilizing both solar power and isotope power to meet the baseline mission goal at the selected planetary location. The results show that an isotope-powered airship is feasible within the lower atmosphere of Venus and Saturn s moon Titan.
The atmospheric escape at Mars: complementing the scenario

NASA Astrophysics Data System (ADS)

Lilensten, Jean; Simon, Cyril; Barthélémy, Mathieu; Thissen, Roland; Ehrenreich, David; Gronoff, Guillaume; Witasse, Olivier

2013-04-01

In the recent years, the presence of dications in the atmospheres of Mars, Venus, Earth and Titan has been modeled and assessed. These studies also suggested that these ions could participate to the escape of the planetary atmospheres because a large fraction of them is unstable and highly ener- getic. When they dissociate, their internal energy is transformed into kinetic energy which may be larger than the escape energy. This study assesses the impact of the doubly-charged ions in the escape of CO2-dominated planetary atmospheres and to compare it to the escape of thermal photo-ions.We solve a Boltzmann transport equation at daytime taking into account the dissociative states of CO++ for a simplified single constituent atmosphere of a 2 case-study planet. We compute the escape of fast ions using a Beer-Lambert approach. We study three test-cases. On a Mars-analog planet in today's conditions, we retrieve the measured electron escape flux. When comparing the two mechanisms (i.e. excluding solar wind effects, sputtering ...), the escape due to the fast ions issuing from the dissociation of dications may account for up to 6% of the total and the escape of thermal ions for the remaining. We show that these two mechanisms cannot explain the escape of the atmosphere since the magnetic field vanished but complement the other processes and allow writing the scenario of the Mars escape. We show that the atmosphere of a Mars analog planet would empty in another giga years and a half. At Venus orbit, the contribution of the dications in the escape rate is negligible.When simulating the hot Jupiter HD209458b, the two processes cannot explain the measured escape flux of C+.
Atmospheric circulations required for thick high-altitude clouds and featureless transit spectra

NASA Astrophysics Data System (ADS)

Wang, H.; Wordsworth, R. D.

2017-12-01

The transmission spectra of exoplanet GJ 1214b and GJ 436b are featureless as measured by current instruments. According to the measured density of these planets, we have reason to believe these planets have atmospheres, and the spectroscopy features of the atmospheres are unexpectedly not shown in the transit spectra. An explanation is high-altitude clouds or hazes are optically thick enough to make the transit spectra flat in the current observed wavelength range. We analyze the atmospheric circulations and vertical mixing that are crucial for the possible existence of the thick high-altitude clouds. We perform a series of GCM simulations with different atmospheric compositions and planetary parameters to reveal the conditions that are required for showing featureless spectra, and study the dynamical processes. We also study the role of cloud particles with different sizes, compositions and spectral characteristics with a radiative transfer model and cloud physics models. Varying the compositions and sizes of the cloud particles results in different requirements for the atmospheric circulations.
Chemical kinetics and modeling of planetary atmospheres

NASA Technical Reports Server (NTRS)

Yung, Yuk L.

1990-01-01

A unified overview is presented for chemical kinetics and chemical modeling in planetary atmospheres. The recent major advances in the understanding of the chemistry of the terrestrial atmosphere make the study of planets more interesting and relevant. A deeper understanding suggests that the important chemical cycles have a universal character that connects the different planets and ultimately link together the origin and evolution of the solar system. The completeness (or incompleteness) of the data base for chemical kinetics in planetary atmospheres will always be judged by comparison with that for the terrestrial atmosphere. In the latter case, the chemistry of H, O, N, and Cl species is well understood. S chemistry is poorly understood. In the atmospheres of Jovian planets and Titan, the C-H chemistry of simple species (containing 2 or less C atoms) is fairly well understood. The chemistry of higher hydrocarbons and the C-N, P-N chemistry is much less understood. In the atmosphere of Venus, the dominant chemistry is that of chlorine and sulfur, and very little is known about C1-S coupled chemistry. A new frontier for chemical kinetics both in the Earth and planetary atmospheres is the study of heterogeneous reactions. The formation of the ozone hole on Earth, the ubiquitous photochemical haze on Venus and in the Jovian planets and Titan all testify to the importance of heterogeneous reactions. It remains a challenge to connect the gas phase chemistry to the production of aerosols.
Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

NASA Technical Reports Server (NTRS)

Steffes, Paul G.

1988-01-01

In the first half of this grant year, laboratory measurements were conducted on the millimeter-wave properties of atmospheric gases under simulated conditions for the outer planet. Significant improvements in the current system have made it possible to accurately characterize the opacity from gaseous NH3 at longer millimeter wavelengths (7 to 10 mm) under simulated Jovian conditions. In the second half of the grant year, it is hoped to extend such measurements to even shorter millimeter-wavelengths. Further analysis and application of the laboratory results to microwave and millimeter-wave absorption data for the outer planets, such as results from Voyager Radio Occultation experiments and earth-based radio astronomical observations will be continued. The analysis of available multispectral microwave opacity data from Venus, including data from the most recent radio astronomical ovservations in the 1.3 to 3.6 cm wavelength range and newly obtained Pioneer-Venus Radio Occulatation measurements at 13 cm, using the laboratory measurements as an interpretative tool will be pursued.
Elemental Analysis of the JSC Mars-1 Soil Simulant using Laser Ablation and Magnetic Separation

NASA Technical Reports Server (NTRS)

Nasab, Ahab S.

2005-01-01

Future long-duration missions to Mars require capabilities in terms of manufacture of structures and chemical compounds essential for human habitat and exploratory activities. Currently, it is not feasible to import all the required raw and finished materials from Earth. In fact, essential items such as structural members as well as various gases for human consumption and material processing need to be largely extracted from the available planetary resources. The resources on Mars include its soil and rocks, its atmosphere and the polar caps. Mars atmosphere consists of 95% carbon dioxide and the balance contains small percentages of oxygen, nitrogen, and argon. The Mars regolith contains many metal oxides in various mineralogical forms. Presently, Martian soil samples are not available. However, a closely matched Martian soil simulant developed by the Johnson Space Center has been available for scientific research and engineering studies. The chemical makeup of this simulant is compared with the data from Viking Lander and Path Finder missions are shown..
Resistance of Bacterial Endospores to Outer Space for Planetary Protection Purposes—Experiment PROTECT of the EXPOSE-E Mission

PubMed Central

Moeller, Ralf; Cadet, Jean; Douki, Thierry; Mancinelli, Rocco L.; Nicholson, Wayne L.; Panitz, Corinna; Rabbow, Elke; Rettberg, Petra; Spry, Andrew; Stackebrandt, Erko; Vaishampayan, Parag; Venkateswaran, Kasthuri J.

2012-01-01

Abstract Spore-forming bacteria are of particular concern in the context of planetary protection because their tough endospores may withstand certain sterilization procedures as well as the harsh environments of outer space or planetary surfaces. To test their hardiness on a hypothetical mission to Mars, spores of Bacillus subtilis 168 and Bacillus pumilus SAFR-032 were exposed for 1.5 years to selected parameters of space in the experiment PROTECT during the EXPOSE-E mission on board the International Space Station. Mounted as dry layers on spacecraft-qualified aluminum coupons, the “trip to Mars” spores experienced space vacuum, cosmic and extraterrestrial solar radiation, and temperature fluctuations, whereas the “stay on Mars” spores were subjected to a simulated martian environment that included atmospheric pressure and composition, and UV and cosmic radiation. The survival of spores from both assays was determined after retrieval. It was clearly shown that solar extraterrestrial UV radiation (λ≥110 nm) as well as the martian UV spectrum (λ≥200 nm) was the most deleterious factor applied; in some samples only a few survivors were recovered from spores exposed in monolayers. Spores in multilayers survived better by several orders of magnitude. All other environmental parameters encountered by the “trip to Mars” or “stay on Mars” spores did little harm to the spores, which showed about 50% survival or more. The data demonstrate the high chance of survival of spores on a Mars mission, if protected against solar irradiation. These results will have implications for planetary protection considerations. Key Words: Planetary protection—Bacterial spores—Space experiment—Simulated Mars mission. Astrobiology 12, 445–456. PMID:22680691
Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems.

PubMed

Shin, Kyuchul; Kumar, Rajnish; Udachin, Konstantin A; Alavi, Saman; Ripmeester, John A

2012-09-11

There is interest in the role of ammonia on Saturn's moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons' atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods.
Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems

PubMed Central

Shin, Kyuchul; Kumar, Rajnish; Udachin, Konstantin A.; Alavi, Saman; Ripmeester, John A.

2012-01-01

There is interest in the role of ammonia on Saturn’s moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons’ atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods. PMID:22908239
Astrobiological Implications of Titan Tholin in Methane Lakes

NASA Astrophysics Data System (ADS)

Khare, Bishun N.; McKay, C. P.; McPherson, S.; Cruikshank, D.; Nna-Mvondo, D.; Sekine, Y.

2010-10-01

We report here on our ongoing research in the Laboratory for Planetary Studies at NASA Ames Research Center dedicated to determine the degree of solubility of Titan tholin in the methane-ethane lakes. Our work is also directed toward confirming the presence of any astrobiologically significant molecules via hydrolysis and pyrolysis of a simulated lake sample. Our previous work conducted at Cornell University and subsequently in the Laboratory for Planetary Studies at NASA Ames Research Center has established that Titan tholin produces amino acids (Khare et al. Icarus 1986) on hydrolysis, and many compounds including adenine on pyrolysis (Khare et al. Adv. Space Res. 1984). Also, our previous work by Thompson et al. (Icarus 1991) has clearly indicated that when energy is supplied to Titan's atmospheric composition (methane and nitrogen), tholin results from hundreds of contemporary compounds, including highly reactive compounds such as azides and isocyanides. Cassini showed that photolysis of methane produces benzene and many polycyclic aromatic hydrocarbons, along with compounds with very high molecular weights (up to 10000 amu), resulting from the photolytic reactions of CH4 with nitrogen. These heavy aerosols, termed "tholins” by Sagan and Khare (Nature 1979), are also synthesized when Titan intercepts charged particles from the magnetosphere of Saturn. Tholins resulting from both of these syntheses eventually descend to the surface of Titan, where some quantity collects in the methane-ethane lakes. This research is supported by a grant from Planetary Atmospheres.
The Planetary and Space Simulation Facilities at DLR Cologne

NASA Astrophysics Data System (ADS)

Rabbow, Elke; Parpart, André; Reitz, Günther

2016-06-01

Astrobiology strives to increase our knowledge on the origin, evolution and distribution of life, on Earth and beyond. In the past centuries, life has been found on Earth in environments with extreme conditions that were expected to be uninhabitable. Scientific investigations of the underlying metabolic mechanisms and strategies that lead to the high adaptability of these extremophile organisms increase our understanding of evolution and distribution of life on Earth. Life as we know it depends on the availability of liquid water. Exposure of organisms to defined and complex extreme environmental conditions, in particular those that limit the water availability, allows the investigation of the survival mechanisms as well as an estimation of the possibility of the distribution to and survivability on other celestial bodies of selected organisms. Space missions in low Earth orbit (LEO) provide access for experiments to complex environmental conditions not available on Earth, but studies on the molecular and cellular mechanisms of adaption to these hostile conditions and on the limits of life cannot be performed exclusively in space experiments. Experimental space is limited and allows only the investigation of selected endpoints. An additional intensive ground based program is required, with easy to access facilities capable to simulate space and planetary environments, in particular with focus on temperature, pressure, atmospheric composition and short wavelength solar ultraviolet radiation (UV). DLR Cologne operates a number of Planetary and Space Simulation facilities (PSI) where microorganisms from extreme terrestrial environments or known for their high adaptability are exposed for mechanistic studies. Space or planetary parameters are simulated individually or in combination in temperature controlled vacuum facilities equipped with a variety of defined and calibrated irradiation sources. The PSI support basic research and were recurrently used for pre-flight test programs for several astrobiological space missions. Parallel experiments on ground provided essential complementary data supporting the scientific interpretation of the data received from the space missions.
Global Environmental Multiscale model - a platform for integrated environmental predictions

NASA Astrophysics Data System (ADS)

Kaminski, Jacek W.; Struzewska, Joanna; Neary, Lori; Dearden, Frank

2017-04-01

The Global Environmental Multiscale model was developed by the Government of Canada as an operational weather prediction model in the mid-1990s. Subsequently, it was used as the host meteorological model for an on-line implementation of air quality chemistry and aerosols from global to the meso-gamma scale. Further model developments led to the vertical extension of the modelling domain to include stratospheric chemistry, aerosols, and formation of polar stratospheric clouds. In parallel, the modelling platform was used for planetary applications where dynamical, radiative transfer and chemical processes in the atmosphere of Mars were successfully simulated. Undoubtedly, the developed modelling platform can be classified as an example capable of the seamless and coupled modelling of the dynamics and chemistry of planetary atmospheres. We will present modelling results for global, regional, and local air quality episodes and the long-term air quality trends. Upper troposphere and lower stratosphere modelling results will be presented in terms of climate change and subsonic aviation emissions modelling. Model results for the atmosphere of Mars will be presented in the context of the 2016 ExoMars mission and the anticipated observations from the NOMAD instrument. Also, we will present plans and the design to extend the GEM model to the F region with further coupling with a magnetospheric model that extends to 15 Re.
Dynamics of the middle atmosphere as observed by the ARISE project

NASA Astrophysics Data System (ADS)

Blanc, Elisabeth

2015-04-01

The atmosphere is a complex system submitted to disturbances in a wide range of scales, including high frequency sources as volcanoes, thunderstorms, tornadoes and at larger scales, gravity waves from deep convection or wind over mountains, atmospheric tides and planetary waves. These waves affect the different atmospheric layers submitted to different temperature and wind systems which strongly control the general atmospheric circulation. The full description of gravity and planetary waves constitutes a challenge for the development of future models of atmosphere and climate. The objective of this paper is to present a review of recent advances obtained in this topic, especially in the framework of the ARISE (Atmospheric dynamics Research InfraStructure in Europe) project
A Prototype Two-Decade Fully-Coupled Fine-Resolution CCSM Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

McClean, Julie L.; Bader, David C; Bryan, Frank O.

2011-01-01

A fully coupled global simulation using the Community Climate System Model (CCSM) was configured using grid resolutions of 0.1{sup o} for the ocean and sea-ice, and 0.25{sup o} for the atmosphere and land, and was run under present-day greenhouse gas conditions for 20 years. It represents one of the first efforts to simulate the planetary system at such high horizontal resolution. The climatology of the circulation of the atmosphere and the upper ocean were compared with observational data and reanalysis products to identify persistent mean climate biases. Intensified and contracted polar vortices, and too cold sea surface temperatures (SSTs) inmore » the subpolar and mid-latitude Northern Hemisphere were the dominant biases produced by the model. Intense category 4 cyclones formed spontaneously in the tropical North Pacific. A case study of the ocean response to one such event shows the realistic formation of a cold SST wake, mixed layer deepening, and warming below the mixed layer. Too many tropical cyclones formed in the North Pacific however, due to too high SSTs in the tropical eastern Pacific. In the North Atlantic anomalously low SSTs lead to a dearth of hurricanes. Agulhas eddy pathways are more realistic than in equivalent stand-alone ocean simulations forced with atmospheric reanalysis.« less
Structural and Trajectory Control of Variable Geometry Planetary Entry Systems

NASA Technical Reports Server (NTRS)

Quadrelli, Marco; Kwok, Kawai; Pellegrino, Sergio

2009-01-01

The results presented in this paper apply to a generic vehicle entering a planetary atmosphere which makes use of a variable geometry change to modulate the heat, drag, and acceleration loads. Two structural concepts for implementing the cone angle variation, namely a segmented shell and a corrugated shell, are presented. A structural analysis of these proposed structural configuration shows that the stress levels are tolerable during entry. The analytic expressions of the longitudinal aerodynamic coefficients are also derived, and guidance laws that track reference heat flux, drag, and aerodynamic acceleration loads are also proposed. These guidance laws have been tested in an integrated simulation environment, and the results indicate that use of variable geometry is feasible to track specific profiles of dynamic load conditions during reentry.
Challenges to Constraining Exoplanet Masses via Transmission Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batalha, Natasha E.; Kempton, Eliza M.-R.; Mbarek, Rostom, E-mail: neb149@psu.edu

MassSpec , a method for determining the mass of a transiting exoplanet from its transmission spectrum alone, was proposed by de Wit and Seager. The premise of this method relies on the planet’s surface gravity being extracted from the transmission spectrum via its effect on the atmospheric scale height, which in turn determines the strength of absorption features. Here, we further explore the applicability of MassSpec to low-mass exoplanets—specifically those in the super-Earth size range for which radial velocity determinations of the planetary mass can be extremely challenging and resource intensive. Determining the masses of these planets is of themore » utmost importance because their nature is otherwise highly unconstrained. Without knowledge of the mass, these planets could be rocky, icy, or gas-dominated. To investigate the effects of planetary mass on transmission spectra, we present simulated observations of super-Earths with atmospheres made up of mixtures of H{sub 2}O and H{sub 2}, both with and without clouds. We model their transmission spectra and run simulations of each planet as it would be observed with James Webb Space Telescope using the NIRISS, NIRSpec, and MIRI instruments. We find that significant degeneracies exist between transmission spectra of planets with different masses and compositions, making it impossible to unambiguously determine the planet’s mass in many cases.« less
Probing clouds in planets with a simple radiative transfer model: the Jupiter case

NASA Astrophysics Data System (ADS)

Mendikoa, Iñigo; Pérez-Hoyos, Santiago; Sánchez-Lavega, Agustín

2012-11-01

Remote sensing of planets evokes using expensive on-orbit satellites and gathering complex data from space. However, the basic properties of clouds in planetary atmospheres can be successfully estimated with small telescopes even from an urban environment using currently available and affordable technology. This makes the process accessible for undergraduate students while preserving most of the physics and mathematics involved. This paper presents the methodology for carrying out a photometric study of planetary atmospheres, focused on the planet Jupiter. The method introduces the basics of radiative transfer in planetary atmospheres, some notions on inverse problem theory and the fundamentals of planetary photometry. As will be shown, the procedure allows the student to derive the spectral reflectivity and top altitude of clouds from observations at different wavelengths by applying a simple but enlightening ‘reflective layer model’. In this way, the planet's atmospheric structure is estimated by students as an inverse problem from the observed photometry. Web resources are also provided to help those unable to obtain telescopic observations of the planets.
The Next Generation of Planetary Atmospheric Probes

NASA Technical Reports Server (NTRS)

Houben, Howard

2005-01-01

Entry probes provide useful insights into the structures of planetary atmospheres, but give only one-dimensional pictures of complex four-dimensional systems that vary on all temporal and spatial scales. This makes the interpretation of the results quite challenging, especially as regards atmospheric dynamics. Here is a planetary meteorologist's vision of what the next generation of atmospheric entry probe missions should be: Dedicated sounding instruments get most of the required data from orbit. Relatively simple and inexpensive entry probes are released from the orbiter, with low entry velocities, to establish ground truth, to clarify the vertical structure, and for adaptive observations to enhance the dataset in preparation for sensitive operations. The data are assimilated onboard in real time. The products, being immediately available, are of immense benefit for scientific and operational purposes (aerobraking, aerocapture, accurate payload delivery via glider, ballooning missions, weather forecasts, etc.).
Spacecraft Radio Scintillation and Solar System Exploration

NASA Technical Reports Server (NTRS)

Woo, Richard

1993-01-01

When a wave propagates through a turbulent medium, scattering by the random refractive index inhomogeneities can lead to a wide variety of phenomena that have been the subject of extensive study. The observed scattering effects include amplitude or intensity scintillation, phase scintillation, angular broadening, and spectral broadening, among others. In this paper, I will refer to these scattering effects collectively as scintillation. Although the most familiar example is probably the twinkling of stars (light wave intensity scintillation by turbulence in the Earth's atmosphere), scintillation has been encountered and investigated in such diverse fields as ionospheric physics, oceanography, radio astronomy, and radio and optical communications. Ever since planetary spacecraft began exploring the solar system, scintillation has appeared during the propagation of spacecraft radio signals through planetary atmospheres, planetary ionospheres, and the solar wind. Early studies of these phenomena were motivated by the potential adverse effects on communications and navigation, and on experiments that use the radio link to conduct scientific investigations. Examples of the latter are radio occultation measurements (described below) of planetary atmospheres to deduce temperature profiles, and the search for gravitational waves. However,these concerns soon gave way to the emergence of spacecraft radio scintillation as a new scientific tool for exploring small-scale dynamics in planetary atmospheres and structure in the solar wind, complementing in situ and other remote sensing spacecraft measurements, as well as scintillation measurements using natural (celestial) radio sources. The purpose of this paper is to briefly describe and review the solar system spacecraft radio scintillation observations, to summarize the salient features of wave propagation analyses employed in interpreting them, to underscore the unique remote sensing capabilities and scientific relevance of the scintillation measurements, and to highlight some of the scientific results obtained to date. Special emphasis is placed on comparing the remote sensing features of planetary and terrestrial scintillation measurements, and on contrasting spacecraft and natural radio source scintillation measurements. I will first discuss planetary atmospheres and ionospheres, and then the solar wind.

Planetary Magnetic Fields and Climate Evolution

NASA Astrophysics Data System (ADS)

Brain, D. A.; Leblanc, F.; Luhmann, J. G.; Moore, T. E.; Tian, F.

We explore the possible connections between magnetic fields and climate at the terrestrial bodies Venus, Earth, Mars, and Titan. Magnetic fields are thought to have negligible effects on the processes that change a planet's climate, except for processes that alter the abundance of atmospheric gases. Particles can be added or removed at the top of an atmosphere, where collisions are infrequent and a more substantial fraction of particles are ionized (and therefore subject to magnetic forces) than at lower altitudes. The absence of a global magnetic field at Mars for much of its history may have contributed to the removal of a substantial fraction of its atmosphere to space. The persistence of a global magnetic field should have decreased both ionization and removal of atmospheric ions by several processes, and may have indirectly decreased the loss rate of neutral particles as well. While it is convenient to think of magnetic fields as shields for planetary atmospheres from impinging plasma (such as the solar wind), observations of ions escaping from Earth's polar cusp regions suggest that magnetic shielding effects may not be as effective as previously thought. One explanation that requires further testing is that magnetic fields transfer momentum and energy from incident plasma to localized regions of the atmosphere, resulting in similar (or possibly greater) escape rates than if the momentum and energy were imparted more globally to the atmosphere in the absence of a magnetic field. Trace gases can be important for climate despite their low relative abundance in planetary atmospheres. At Venus, removal of O+ over the history of the planet has likely contributed to the loss of water from the atmosphere, leading to a runaway greenhouse situation and having implications for the chemistry of atmosphere-surface interactions. Conversely, Titan's robust atmospheric chemistry may result from the addition of trace amounts of oxygen from Saturn's magnetosphere, which then participate in chemical reactions that produce carbon monoxide (CO) and carbon dioxide (CO2). Models of the entire atmosphere system (including planetary plasma interactions) should continue to shed light on the connections between magnetic fields and climate, as well as models that consider a single planetary body in both magnetized and unmagnetized states. Future measurements, such as those that will be made by the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft to Mars, will provide better constraints on the importance of magnetic fields in the evolution of atmospheres.
Building Better Planet Populations for EXOSIMS

NASA Astrophysics Data System (ADS)

Garrett, Daniel; Savransky, Dmitry

2018-01-01

The Exoplanet Open-Source Imaging Mission Simulator (EXOSIMS) software package simulates ensembles of space-based direct imaging surveys to provide a variety of science and engineering yield distributions for proposed mission designs. These mission simulations rely heavily on assumed distributions of planetary population parameters including semi-major axis, planetary radius, eccentricity, albedo, and orbital orientation to provide heuristics for target selection and to simulate planetary systems for detection and characterization. The distributions are encoded in PlanetPopulation modules within EXOSIMS which are selected by the user in the input JSON script when a simulation is run. The earliest written PlanetPopulation modules available in EXOSIMS are based on planet population models where the planetary parameters are considered to be independent from one another. While independent parameters allow for quick computation of heuristics and sampling for simulated planetary systems, results from planet-finding surveys have shown that many parameters (e.g., semi-major axis/orbital period and planetary radius) are not independent. We present new PlanetPopulation modules for EXOSIMS which are built on models based on planet-finding survey results where semi-major axis and planetary radius are not independent and provide methods for sampling their joint distribution. These new modules enhance the ability of EXOSIMS to simulate realistic planetary systems and give more realistic science yield distributions.
Filter Media Tests Under Simulated Martian Atmospheric Conditions

NASA Technical Reports Server (NTRS)

Agui, Juan H.

2016-01-01

Human exploration of Mars will require the optimal utilization of planetary resources. One of its abundant resources is the Martian atmosphere that can be harvested through filtration and chemical processes that purify and separate it into its gaseous and elemental constituents. Effective filtration needs to be part of the suite of resource utilization technologies. A unique testing platform is being used which provides the relevant operational and instrumental capabilities to test articles under the proper simulated Martian conditions. A series of tests were conducted to assess the performance of filter media. Light sheet imaging of the particle flow provided a means of detecting and quantifying particle concentrations to determine capturing efficiencies. The media's efficiency was also evaluated by gravimetric means through a by-layer filter media configuration. These tests will help to establish techniques and methods for measuring capturing efficiency and arrestance of conventional fibrous filter media. This paper will describe initial test results on different filter media.
Parametric Simulations of the Great Dark Spots of Neptune

NASA Astrophysics Data System (ADS)

Deng, Xiaolong; Le Beau, R.

2006-09-01

Observations by Voyager II and the Hubble Space Telescope of the Great Dark Spots (GDS) of Neptune suggest that large vortices with lifespans of years are not uncommon occurrences in the atmosphere of Neptune. The variability of these features over time, in particular the complex motions of GDS-89, make them challenging candidates to simulate in atmospheric models. Previously, using the Explicit Planetary Isentropic-Coordinate (EPIC) General Circulation Model, LeBeau and Dowling (1998) simulated the GDS-like vortex features. Qualitatively, the drift, oscillation, and tail-like features of GDS-89 were recreated, although precise numerical matches were only achieved for the meridional drift rate. In 2001, Stratman et al. applied EPIC to simulate the formation of bright companion clouds to the Great Dark Spots. In 2006, Dowling et al. presented a new version of EPIC, which includes hybrid vertical coordinate, cloud physics, advanced chemistry, and new turbulence models. With the new version of EPIC, more observation results, and more powerful computers, it is the time to revisit CFD simulations of the Neptune's atmosphere and do more detailed work on GDS-like vortices. In this presentation, we apply the new version of EPIC to simulate GDS-89. We test the influences of different parameters in the EPIC model: potential vorticity gradient, wind profile, initial latitude, vortex shape, and vertical structure. The observed motions, especially the latitudinal drift and oscillations in orientation angle and aspect ratio, are used as diagnostics of these unobserved atmospheric conditions. Increased computing power allows for more refined and longer simulations and greater coverage of the parameter space than previous efforts. Improved quantitative results have been achieved, including voritices with near eight-day oscillations and comparable variations in shape to GDS-89. This research has been supported by Kentucky NASA EPSCoR.
Seeing the Invisible: Educating the Public on Planetary Magnetic Fields and How they Affect Atmospheres

NASA Astrophysics Data System (ADS)

Fillingim, M. O.; Brain, D. A.; Peticolas, L. M.; Schultz, G.; Yan, D.; Guevara, S.; Randol, S.

2010-08-01

Magnetic fields and charged particles are difficult for school children, the general public, and scientists alike to visualize. But studies of planetary magnetospheres and ionospheres have broad implications for planetary evolution, from the deep interior to the ancient climate, that are important to communicate to each of these audiences. This presentation will highlight the visualization materials that we are developing to educate audiences on the magnetic fields of planets and how they affect the atmosphere. The visualization materials that we are developing consist of simplified data sets that can be displayed on spherical projection systems and portable 3-D rigid models of planetary magnetic fields.
A New Perspective on Trapped Radiation Belts in Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Diaz, A.; Lodhi, M. A. K.; Wilson, T. L.

2005-01-01

The charged particle fluxes trapped in the magnetic dipole fields of certain planets in our Solar System are interesting signatures of planetary properties in space physics. They also represent a source of potentially hazardous radiation to spacecraft during planetary and interplanetary exploration. The Earth s trapped radiation belts have been studied for years and the physical mechanisms by which primary radiation from the Sun and Galaxy is captured is well understood. The higher-energy particles collide with molecules in the planetary atmosphere and initiate large cascades of secondary radiation which itself becomes trapped by the magnetic dipole field of the planet. Some of it is even backscattered as albedo neutrons.
SHINE, The SpHere INfrared survey for Exoplanets

NASA Astrophysics Data System (ADS)

Chauvin, G.; Desidera, S.; Lagrange, A.-M.; Vigan, A.; Feldt, M.; Gratton, R.; Langlois, M.; Cheetham, A.; Bonnefoy, M.; Meyer, M.

2017-12-01

The SHINE survey for SPHERE High-contrast ImagiNg survey for Exoplanets, is a large near-infrared survey of 400-600 young, nearby stars and represents a significant component of the SPHERE consortium Guaranteed Time Observations consisting in 200 observing nights. The scientific goals are: i) to characterize known planetary systems (architecture, orbit, stability, luminosity, atmosphere); ii) to search for new planetary systems using SPHERE's unprecedented performance; and finally iii) to determine the occurrence and orbital and mass function properties of the wide-orbit, giant planet population as a function of the stellar host mass and age. Combined, the results will increase our understanding of planetary atmospheric physics and the processes of planetary formation and evolution.
Martian Atmospheric and Ionospheric plasma Escape

NASA Astrophysics Data System (ADS)

Lundin, Rickard

2016-04-01

Solar forcing is responsible for the heating, ionization, photochemistry, and erosion processes in the upper atmosphere throughout the lifetime of the terrestrial planets. Of the four terrestrial planets, the Earth is the only one with a fully developed biosphere, while our kin Venus and Mars have evolved into arid inhabitable planets. As for Mars, there are ample evidences for an early Noachian, water rich period on Mars. The question is, what made Mars evolve so differently compared to the Earth? Various hydrosphere and atmospheric evolution scenarios for Mars have been forwarded based on surface morphology, chemical composition, simulations, semi-empiric (in-situ data) models, and the long-term evolution of the Sun. Progress has been made, but the case is still open regarding the changes that led to the present arid surface and tenuous atmosphere at Mars. This presentation addresses the long-term variability of the Sun, the solar forcing impact on the Martian atmosphere, and its interaction with the space environment - an electromagnetic wave and particle interaction with the upper atmosphere that has implications for its photochemistry, composition, and energization that governs thermal and non-thermal escape. Non-thermal escape implies an electromagnetic upward energization of planetary ions and molecules to velocities above escape velocity, a process governed by a combination of solar EUV radiation (ionization), and energy and momentum transfer by the solar wind. The ion escape issue dates back to the early Soviet and US-missions to Mars, but the first more accurate estimates of escape rates came with the Phobos-2 mission in 1989. Better-quality ion composition measurement results of atmospheric/ionospheric ion escape from Mars, obtained from ESA Mars Express (MEX) instruments, have improved our understanding of the ion escape mechanism. With the NASA MAVEN spacecraft orbiting Mars since Sept. 2014, dual in-situ measurement with plasma instruments are now carried out in the Martian planetary realm. Of particular interest from a planetary atmospheric escape point of view is the long-term implications of solar forcing. From ASPERA-data on MEX it has been possible to cover the transition from cycle 23 up to the cycle 24 maximum, data displaying clear solar cycle dependence. The planetary ion escape rate increased from solar minimum to solar maximum by a factor of 10. From a regression analysis using ion escape fluxes and solar forcing proxies, a "back-casting" tool is developed [1], enabling determination of the planetary ion escape back in time based on long-term solar forcing proxies (F10.7, sunspot number). The tool may be applied to other long-term solar proxies, such as the radiogenic isotopes in the Earth's atmosphere, 10Be and 14C. The cosmic-ray production of these long-lifetime (>10000 year) isotopes is modulated by the solar-heliospheric magnetic flux, i.e. an indirect measure of solar magnetic activity. Beyond that there is so far only one additional rough "back-casting" tool, the "Sun-in-time", a method whereby the age of, EUV/UV radiation, and mass-loss of other sun-like stars are determined [2, 3]. [1] Lundin et al., Geophys. Res. Lett., 40, 23, pp. 6028-6032, 2013. [2] Wood et al., ApJ, 574:412-425, 2002. [3] Ribas et al., ApJ., 622:680-694, 2005
Equations of State: Gateway to Planetary Origin and Evolution (Invited)

NASA Astrophysics Data System (ADS)

Melosh, J.

2013-12-01

Research over the past decades has shown that collisions between solid bodies govern many crucial phases of planetary origin and evolution. The accretion of the terrestrial planets was punctuated by planetary-scale impacts that generated deep magma oceans, ejected primary atmospheres and probably created the moons of Earth and Pluto. Several extrasolar planetary systems are filled with silicate vapor and condensed 'tektites', probably attesting to recent giant collisions. Even now, long after the solar system settled down from its violent birth, a large asteroid impact wiped out the dinosaurs, while other impacts may have played a role in the origin of life on Earth and perhaps Mars, while maintaining a steady exchange of small meteorites between the terrestrial planets and our moon. Most of these events are beyond the scale at which experiments are possible, so that our main research tool is computer simulation, constrained by the laws of physics and the behavior of materials during high-speed impact. Typical solar system impact velocities range from a few km/s in the outer solar system to 10s of km/s in the inner system. Extrasolar planetary systems expand that range to 100s of km/sec typical of the tightly clustered planetary systems now observed. Although computer codes themselves are currently reaching a high degree of sophistication, we still rely on experimental studies to determine the Equations of State (EoS) of materials critical for the correct simulation of impact processes. The recent expansion of the range of pressures available for study, from a few 100 GPa accessible with light gas guns up to a few TPa from current high energy accelerators now opens experimental access to the full velocity range of interest in our solar system. The results are a surprise: several groups in both the USA and Japan have found that silicates and even iron melt and vaporize much more easily in an impact than previously anticipated. The importance of these findings is illustrated by the impact origin of our Moon. Computer simulations that do not take account of the liquid/vapor phase change are unable to retain any material in orbit around the Earth after a planetary impact. A purely gaseous disk around the Earth is wracked by gravitational instabilities and soon collapses back onto the Earth. Only if the silicate EoS also includes a liquid phase can a disk remain stable long enough to condense into a moon. The implications of this new-found ease of vaporization have yet to be fully explored, but it seems clear that current ideas must undergo extensive revision. More melt and vapor production in impacts implies much larger volume changes of the impacted materials and hence more energetic post-impact expansion. EoSs are thus of vital importance to our understanding of the evolution of planetary systems. Computer simulations can (and must!) substitute for experiments for many aspects of large planetary collisions, but so far experiments are leading theory in accurate determination of equations of state. Yet, the fidelity of the computer simulations to Nature can be only as good as the accuracy of the inputs, making further experimental study of EoS a central task in the exploration and elucidation of our solar system and of planetary systems in general.
Modeling the Surface Temperature of Earth-like Planets

NASA Astrophysics Data System (ADS)

Vladilo, Giovanni; Silva, Laura; Murante, Giuseppe; Filippi, Luca; Provenzale, Antonello

2015-05-01

We introduce a novel Earth-like planet surface temperature model (ESTM) for habitability studies based on the spatial-temporal distribution of planetary surface temperatures. The ESTM adopts a surface energy balance model (EBM) complemented by: radiative-convective atmospheric column calculations, a set of physically based parameterizations of meridional transport, and descriptions of surface and cloud properties more refined than in standard EBMs. The parameterization is valid for rotating terrestrial planets with shallow atmospheres and moderate values of axis obliquity (ɛ ≲ 45{}^\\circ ). Comparison with a 3D model of atmospheric dynamics from the literature shows that the equator-to-pole temperature differences predicted by the two models agree within ≈ 5 K when the rotation rate, insolation, surface pressure and planet radius are varied in the intervals 0.5≲ {Ω }/{{{Ω }}\\oplus }≲ 2, 0.75≲ S/{{S}\\circ }≲ 1.25, 0.3≲ p/(1 bar)≲ 10, and 0.5≲ R/{{R}\\oplus }≲ 2, respectively. The ESTM has an extremely low computational cost and can be used when the planetary parameters are scarcely known (as for most exoplanets) and/or whenever many runs for different parameter configurations are needed. Model simulations of a test-case exoplanet (Kepler-62e) indicate that an uncertainty in surface pressure within the range expected for terrestrial planets may impact the mean temperature by ˜ 60 K. Within the limits of validity of the ESTM, the impact of surface pressure is larger than that predicted by uncertainties in rotation rate, axis obliquity, and ocean fractions. We discuss the possibility of performing a statistical ranking of planetary habitability taking advantage of the flexibility of the ESTM.
PROBABILITY OF CME IMPACT ON EXOPLANETS ORBITING M DWARFS AND SOLAR-LIKE STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kay, C.; Opher, M.; Kornbleuth, M., E-mail: ckay@bu.edu

2016-08-01

Solar coronal mass ejections (CMEs) produce adverse space weather effects at Earth. Planets in the close habitable zone of magnetically active M dwarfs may experience more extreme space weather than at Earth, including frequent CME impacts leading to atmospheric erosion and leaving the surface exposed to extreme flare activity. Similar erosion may occur for hot Jupiters with close orbits around solar-like stars. We have developed a model, Forecasting a CME's Altered Trajectory (ForeCAT), which predicts a CME's deflection. We adapt ForeCAT to simulate CME deflections for the mid-type M dwarf V374 Peg and hot Jupiters with solar-type hosts. V374 Peg'smore » strong magnetic fields can trap CMEs at the M dwarfs's Astrospheric Current Sheet, that is, the location of the minimum in the background magnetic field. Solar-type CMEs behave similarly, but have much smaller deflections and do not become trapped at the Astrospheric Current Sheet. The probability of planetary impact decreases with increasing inclination of the planetary orbit with respect to the Astrospheric Current Sheet: 0.5–5 CME impacts per day for M dwarf exoplanets, 0.05–0.5 CME impacts per day for solar-type hot Jupiters. We determine the minimum planetary magnetic field necessary to shield a planet's atmosphere from CME impacts. M dwarf exoplanets require values between tens and hundreds of Gauss. Hot Jupiters around a solar-type star, however, require a more reasonable <30 G. These values exceed the magnitude required to shield a planet from the stellar wind, suggesting that CMEs may be the key driver of atmospheric losses.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Patnaik, P. C.

The SIGMET mesoscale meteorology simulation code represents an extension, in terms of physical modelling detail and numerical approach, of the work of Anthes (1972) and Anthes and Warner (1974). The code utilizes a finite difference technique to solve the so-called primitive equations which describe transient flow in the atmosphere. The SIGMET modelling contains all of the physics required to simulate the time dependent meteorology of a region with description of both the planetary boundary layer and upper level flow as they are affected by synoptic forcing and complex terrain. The mathematical formulation of the SIGMET model and the various physicalmore » effects incorporated into it are summarized.« less
Scaling up Planetary Dynamo Modeling to Massively Parallel Computing Systems: The Rayleigh Code at ALCF

NASA Astrophysics Data System (ADS)

Featherstone, N. A.; Aurnou, J. M.; Yadav, R. K.; Heimpel, M. H.; Soderlund, K. M.; Matsui, H.; Stanley, S.; Brown, B. P.; Glatzmaier, G.; Olson, P.; Buffett, B. A.; Hwang, L.; Kellogg, L. H.

2017-12-01

In the past three years, CIG's Dynamo Working Group has successfully ported the Rayleigh Code to the Argonne Leadership Computer Facility's Mira BG/Q device. In this poster, we present some our first results, showing simulations of 1) convection in the solar convection zone; 2) dynamo action in Earth's core and 3) convection in the jovian deep atmosphere. These simulations have made efficient use of 131 thousand cores, 131 thousand cores and 232 thousand cores, respectively, on Mira. In addition to our novel results, the joys and logistical challenges of carrying out such large runs will also be discussed.
On Star-Planet Interaction: Magnetospheric Dynamics and Atmospheric Evolution

NASA Astrophysics Data System (ADS)

Tilley, Matthew Tilley

With the explosion of exoplanetary discoveries, the question of planetary habitability is at the forefront, and generates many interesting and complex questions. One of those questions: Are planetary global magnetic fields necessary for the development of complex surface organics and the development of life? Does a global field protect planetary atmospheres? What detection signatures can be gleaned from a planet or moon with a global field as opposed to one without? We have a wealth of in situ magnetospheric data from Earth, as well as solar system planets and their moons from several vital satellite missions, such as the Voyager missions, the Pioneer missions, Galileo, Cassini, Messenger, MAVEN, and New Horizons. Due to the distances involved, it is not tenable to send satellites to obtain data at exoplanetary bodies, so we rely on simulations and using solar system data as analog environments to help set ground truth validation for the numerical work. In this dissertation, I use a multifluid plasma model for gas giant magnetospheres to predict the potential dynamical consequences and detection signatures for giant exoplanets in a warm orbit (˜0.2 AU). I discuss the dynamics of plasma loss from an exomoon injected torus, and how the total mass flux out of the system is altered by increased stellar wind forcing as a function of orbital semi-major axis. Detection signatures for such a planet, including transit depth modifications due to plasma densities and radio emissions, show promise for further detecting and characterizing future systems. I also improve the multifluid model by implementing a full treatment of pressure anisotropy at Saturn, with a focus on the dynamics and structure of the magnetosphere. The improvements to the physics of the model generate more accurate system when compared to Cassini data; the anisotropic simulations show stronger current confinement of the Enceladus torus, consistent and well-structure flux interchange events, and global corotational convection that match more closely with the Cassini data than the isotropic model. Turning from giant planets to terrestrial, I use a coupled one-dimensional photochemical and radiative-convective climate model to investigate the effects of M dwarf stellar flare activity on an Earth-like atmosphere for an unmagnetized planet in the nominal habitable zone. I find that EM-only activity - even to the level of some of the most active stars yet observed - is insufficient at the age of the universe to reduce the ozone column to the point that UV-C radiation can reach the surface. However, repeated proton events from frequent daily flare activity, which has been observed on several M dwarfs, can erode the ozone column by several orders of magnitude, allowing the surface of the planet to be bathed in UV-C, which is sterilizing and detrimental to the development of complex organic structures. The ability of a strong planetary magnetic field to deflect incoming stellar wind and flare-energized protons seems to be of import to maintain surface habitability. I also use scaling laws to predict a potential atomic oxygen auroral signal from Proxima Centauri b, the detection of which would constrain the presence of an atmosphere and point to the presence of a magnetic field. The increased forcing from Proxima Centauri's stellar wind is expected to drive powerful emissions, orders of magnitude stronger than at Earth, and within easy reach of the next generation of observational telescopic instruments. Magnetic fields do seem to be important for both detection and potential shielding of the atmosphere of exoplanets, but much work remains to be performed. Future observations combined with simulations validated against solar system star-planet interactions will likely provide answers to these questions, and perhaps lead to a focus on specific planetary targets for extensive investigation of astrobiological interest.
Combining VPL tools with NEMESIS to Probe Hot Jupiter Exoclimes for JWST

NASA Astrophysics Data System (ADS)

Afrin Badhan, Mahmuda; Kopparapu, Ravi Kumar; Domagal-Goldman, Shawn; Hébrard, Eric; Deming, Drake; Barstow, Joanna; Claire, Mark; Irwin, Patrick GJ; Mandell, Avi; Batalha, Natasha; Garland, Ryan

2016-06-01

Hot Jupiters are the most readily detected exoplanets by present technology. Since the scorching temperatures (>1000K) from high stellar irradiation levels do not allow for cold traps to form in their atmospheres, we can constrain their envelope’s elemental composition with greater confidence compared to our own Jupiter. Thus highly irradiated giant exoplanets hold keys to advancing our understanding of the origin and evolution of planetary systems.Constraining the atmospheric constituents through retrieval methods demands high-precision spectroscopic measurements and robust models to match those measurements. The former will be provided by NASA’s upcoming missions such as JWST. We meet the latter by producing self-consistent retrievals. Here I present modeling results for the temperature structure and photochemical gas abundances of water, methane, carbon dioxide and carbon monoxide, in the dayside atmospheres of selected H2-dominated hot Jupiters observed by present space missions and JWST/NIRSpec simulations, for two [C]/[O] metallicity ratios.The photochemical models were computed using a recently upgraded version of the NASA Astrobiology Institute’s VPL/Atmos software suite. For the radiative transfer and retrieval work, I have utilized a combination of two different numerical approaches in the extensively validated NEMESIS Atmospheric Retrieval Algorithm (Oxford Planetary Group). I have also represented the temperature profile in an analytical radiative equilibrium form to ascertain their physical plausibility. Finally, high-temperature (T> 1000K) spectroscopic opacity databases are slowly but continually being improved. Since this carries the potential of impacting irradiated atmospheric models quite significantly, I also talk about the potential observable impact of such improvements on the retrieval results.
Impact of clouds in the JWST and LUVOIR simulated transmission spectra of TRAPPIST-1 planets in the habitable zone

NASA Astrophysics Data System (ADS)

Fauchez, Thomas; Turbet, Martin; Mandell, Avi; Kopparapu, Ravi Kumar; Arney, Giada; Domagal-Goldman, Shawn

2018-06-01

M-dwarfs are the most common type of stars in our galaxy. Ultra-cool dwarfs (T < 2700 K) are a sub-stellar class of late M-dwarfs and represent nearly ~ 15% of astronomical objects in the stellar neighborhood of the Sun. Their smaller size than regular M-dwarfs allows easier detection of rocky exoplanets in close orbits, and this potential was recently realized by the discovery of the TRAPPIST-1 system. Located about 12 pc away, TRAPPIST-1 has seven known planets, and it is one of the most promising rocky-planet systems for follow-up observations due to the depths of the transit signals. Transit-timing variation (TTVs) measurements of the TRAPPIST-1 planets suggest terrestrial or volatile-rich composition. Also, it has been found that three planets (TRAPPIST-1 e, f and g) are in the Habitable Zone (HZ) where surface temperatures would allow surface water to exist. These planets will be prime targets for atmospheric characterization with JWST owing to their relative proximity to Earth and frequent planetary transits.Atmospheric properties are major components of planet habitability. However, the detectability of gaseous features on rocky planets in the HZ may be severely impacted by the presence of clouds and/or hazes in their atmosphere. We have already seen this phenomenon in the “flat” transit transmission spectra of larger exoplanets such as GJ 1214b, WASP-31b, WASP-12b and HATP-12b.In this work, we use the LMDG global climate model to simulate several possibilities of atmospheres for TRAPPIST-1 e, f and 1g: 1) Archean Earth, 2) modern Earth and 3) CO2-dominated atmospheres. We also calculate synthetic transit spectra using the GSFC Planetary Spectrum Generator (PSG), and determine the number of transits needed to observe key spectral features for both JWST and future telescopes (ARIEL, LUVOIR, HabEx). We will identify differences in the spectra of cloudy vs non-cloudy, and determine how much information on spatial variability in atmosphere characteristics can be extracted from time-resolved transit and eclipse mapping. A particular attention will be given to the impact of the atmospheric variability when adding transit spectra, and how this may affect atmospheric parameter retrievals.
Scale Interactions in the Tropics from a Simple Multi-Cloud Model

NASA Astrophysics Data System (ADS)

Niu, X.; Biello, J. A.

2017-12-01

Our lack of a complete understanding of the interaction between the moisture convection and equatorial waves remains an impediment in the numerical simulation of large-scale organization, such as the Madden-Julian Oscillation (MJO). The aim of this project is to understand interactions across spatial scales in the tropics from a simplified framework for scale interactions while a using a simplified framework to describe the basic features of moist convection. Using multiple asymptotic scales, Biello and Majda[1] derived a multi-scale model of moist tropical dynamics (IMMD[1]), which separates three regimes: the planetary scale climatology, the synoptic scale waves, and the planetary scale anomalies regime. The scales and strength of the observed MJO would categorize it in the regime of planetary scale anomalies - which themselves are forced from non-linear upscale fluxes from the synoptic scales waves. In order to close this model and determine whether it provides a self-consistent theory of the MJO. A model for diabatic heating due to moist convection must be implemented along with the IMMD. The multi-cloud parameterization is a model proposed by Khouider and Majda[2] to describe the three basic cloud types (congestus, deep and stratiform) that are most responsible for tropical diabatic heating. We implement a simplified version of the multi-cloud model that is based on results derived from large eddy simulations of convection [3]. We present this simplified multi-cloud model and show results of numerical experiments beginning with a variety of convective forcing states. Preliminary results on upscale fluxes, from synoptic scales to planetary scale anomalies, will be presented. [1] Biello J A, Majda A J. Intraseasonal multi-scale moist dynamics of the tropical atmosphere[J]. Communications in Mathematical Sciences, 2010, 8(2): 519-540. [2] Khouider B, Majda A J. A simple multicloud parameterization for convectively coupled tropical waves. Part I: Linear analysis[J]. Journal of the atmospheric sciences, 2006, 63(4): 1308-1323. [3] Dorrestijn J, Crommelin D T, Biello J A, et al. A data-driven multi-cloud model for stochastic parametrization of deep convection[J]. Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 2013, 371(1991): 20120374.
Computation of the Transmitted and Polarized Scattered Fluxes by the Exoplanet HD 189733b in X-Rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marin, Frédéric; Grosso, Nicolas, E-mail: frederic.marin@astro.unistra.fr

2017-02-01

Thousands of exoplanets have been detected, but only one exoplanetary transit was potentially observed in X-rays from HD 189733A. What makes the detection of exoplanets so difficult in this band? To answer this question, we run Monte-Carlo radiative transfer simulations to estimate the amount of X-ray flux reprocessed by HD 189733b. Despite its extended evaporating atmosphere, we find that the X-ray absorption radius of HD 189733b at 0.7 keV, which is the mean energy of the photons detected in the 0.25–2 keV energy band by XMM-Newton , is ∼1.01 times the planetary radius for an atmosphere of atomic hydrogen andmore » helium (including ions), and produces a maximum depth of ∼2.1% at ∼±46 minutes from the center of the planetary transit on the geometrically thick and optically thin corona. We compute numerically in the 0.25–2 keV energy band that this maximum depth is only of ∼1.6% at ∼±47 minutes from the transit center, and not very sensitive to the metal abundance, assuming that adding metals in the atmosphere would not dramatically change the density–temperature profile. Regarding a direct detection of HD 189733b in X-rays, we find that the amount of flux reprocessed by the exoplanetary atmosphere varies with the orbital phase, spanning between three and five orders of magnitude fainter than the flux of the primary star. Additionally, the degree of linear polarization emerging from HD 189733b is <0.003%, with maximums detected near planetary greatest elongations. This implies that both the modulation of the X-ray flux with the orbital phase and the scatter-induced continuum polarization cannot be observed with current X-ray facilities.« less
Research at the Stanford Center for Radar Astronomy

NASA Technical Reports Server (NTRS)

1973-01-01

Theoretical and experimental radio and radar studies are presented concerning lunar and planetary atmospheres and surfaces; the sun and interplanetary medium; and software and hardware conceived while doing research. Emphasis is given to probe and radio accumulation measurements of planetary atmospheres. A list is included of recent publications, technical and scientific reports, and symposia with papers.
Ultraviolet emissions from the upper atmospheres of the planets

NASA Technical Reports Server (NTRS)

Moos, H. W.

1981-01-01

Some recent results on planetary upper atmospheres obtained by means of orbiting ultraviolet observatories are reviewed with emphasis on Jupiter and Io torus. Consideration is given to long-term variation in Jovian Ly alpha emission, UV polar auroras on Jupiter, and UV emission from the Io torus. Requirements for UV planetary astronomy are briefly discussed.

Soft X-Ray Emissions from Planets and Moons

NASA Technical Reports Server (NTRS)

Bhardwaj, A.; Gladstone, G. R.; Elsner, R. F.; Waite, J. H., Jr.; Grodent, D.; Cravens, T. E.; Howell, R. R.; Metzger, A. E.; Ostgaard, N.; Maurellis, A.;

2002-01-01

A wide variety of solar system planetary bodies are now known to radiate in the soft x-ray energy (<5 keV) regime. These include planets (Earth, Jupiter, Venus, Saturn): bodies having thick atmosphere and with/without intrinsic magnetic field; planetary satellites (Moon, Io, Europa, Ganymede): bodies with no/thin atmosphere; and comets and Io plasma torus: bodies having extended tenuous atmosphere. Several different mechanisms have been proposed to explain the generation of soft x-rays from these objects. whereas in the hard x-ray energy range (>10 keV) x-rays mainly result from electron bremsstrahlung process. In this paper we present a brief review of the x-ray observations on each of the planetary bodies and discuss their characteristics and proposed source mechanisms.

Radiative transfer in spherical shell atmospheres. I - Rayleigh scattering

NASA Technical Reports Server (NTRS)

Adams, C. N.; Kattawar, G. W.

1978-01-01

The plane-parallel approximation and the more realistic spherical shell approximation for the radiance reflected from a planetary atmosphere are compared and are applied to the study of a planet the size of the earth with a homogeneous conservative Rayleigh scattering atmosphere extending to a height of 100 km. Inadequacies of the approximations are considered. Radiance versus height distributions for both single and multiple scattering are presented, as are results for the fractional radiance from altitudes in the atmosphere which contribute to the total unidirectional reflected radiance at the top of the atmosphere. The data can be used for remote sensing applications and planetary spectroscopy.
Investigation of the small-scale structure and dynamics of Uranus' atmosphere

NASA Technical Reports Server (NTRS)

Eshleman, Von R.; Hinson, David P.

1991-01-01

This document constitutes the final technical report of the Uranus Analysis Program. Papers and/or abstracts resulting from this research are presented. The following topics are covered: (1) past and future of radio occultation studies of planetary atmospheres; (2) equatorial waves in the stratosphere of Uranus; (3) the atmosphere of Uranus- results of radio occultation measurements with Voyager 2; (4) Uranus' atmospheric dynamics and circulation; (5) small-scale structure and dynamics in the atmosphere of Uranus; (6) evidence for inertia-gravity waves in the stratosphere of Uranus derived from Voyager 2 radio occultation data; and (7) planetary waves in the equatorial stratosphere of Uranus.
Escape and fractionation of volatiles and noble gases: from Mars-sized planetary embryos to growing protoplanets

NASA Astrophysics Data System (ADS)

Odert, Petra; Lammer, Helmut; Erkaev, Nikolai V.; Nikolaou, Athanasia; Lichtenegger, Herbert I. M.; Johnstone, Colin P.; Kislyakova, Kristina G.; Leitzinger, Martin; Tosi, Nicola

2017-04-01

Planetary embryos form larger planetary objects via collisions. Such Moon- to Mars-sized bodies can have magma oceans. During the solidification of their magma oceans planetary embryos may therefore degas significant amounts of their volatiles, forming H2O/CO2 dominated steam atmospheres. Such atmospheres may escape efficiently due to the low gravity of these objects and the high EUV emission of the young host star. Planets forming from such building blocks could therefore be drier than expected. We model the energy-limited outflow of hydrogen which is able to drag along heavier species such as O and CO2. We take into account different stellar EUV evolution tracks to investigate the loss of steam atmospheres from Mars-sized planetary embryos at different orbital distances. We find that the estimated envelopes are typically lost within a few to a few tens of Myr. Moreover, we address the influence on protoplanet evolution using Venus as an example. We investigate different early evolution scenarios and constrain realistic cases by comparing modeled noble gas isotope ratios with presently observed ones. We are able to reproduce current ratios by assuming either a pure steam atmosphere or a mixture with accreted hydrogen from the protoplanetary nebula. Despite being able to find solutions for different parameter combinations, our results favor a low-activity Sun with possibly a small amount of residual H from the protoplanetary nebula. In other cases too much CO2 is lost during evolution, which is inconsistent with Venus' present atmosphere. A critical issue is likely the time at which the initial steam atmosphere is outgassed.
Exploring JWST's Capability to Constrain Habitability on Simulated Terrestrial TESS Planets

NASA Astrophysics Data System (ADS)

Tremblay, Luke; Britt, Amber; Batalha, Natasha; Schwieterman, Edward; Arney, Giada; Domagal-Goldman, Shawn; Mandell, Avi; Planetary Systems Laboratory; Virtual Planetary Laboratory

2017-01-01

In the following, we have worked to develop a flexible "observability" scale of biologically relevant molecules in the atmospheres of newly discovered exoplanets for the instruments aboard NASA's next flagship mission, the James Webb Space Telescope (JWST). We sought to create such a scale in order to provide the community with a tool with which to optimize target selection for JWST observations based on detections of the upcoming Transiting Exoplanet Satellite Survey (TESS). Current literature has laid the groundwork for defining both biologically relevant molecules as well as what characteristics would make a new world "habitable", but it has so far lacked a cohesive analysis of JWST's capabilities to observe these molecules in exoplanet atmospheres and thereby constrain habitability. In developing our Observability Scale, we utilized a range of hypothetical planets (over planetary radii and stellar insolation) and generated three self-consistent atmospheric models (of dierent molecular compositions) for each of our simulated planets. With these planets and their corresponding atmospheres, we utilized the most accurate JWST instrument simulator, created specically to process transiting exoplanet spectra. Through careful analysis of these simulated outputs, we were able to determine the relevant parameters that effected JWST's ability to constrain each individual molecular bands with statistical accuracy and therefore generate a scale based on those key parameters. As a preliminary test of our Observability Scale, we have also applied it to the list of TESS candidate stars in order to determine JWST's observational capabilities for any soon-to-be-detected planet in those solar systems.
Atmospheric escape from the TRAPPIST-1 planets and implications for habitability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Chuanfei; Jin, Meng; Lingam, Manasvi

Here, the presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question of whether the seven Earth-sized planets transiting the recently discovered ultracool dwarf star TRAPPIST-1 are capable of retaining their atmospheres. To this effect, we carry out numerical simulations to characterize the stellar wind of TRAPPIST-1 and the atmospheric ion escape rates for all of the seven planets. We also estimate the escape rates analytically and demonstrate that they are in good agreement with the numerical results. We conclude that themore » outer planets of the TRAPPIST-1 system are capable of retaining their atmospheres over billion-year timescales. The consequences arising from our results are also explored in the context of abiogenesis, biodiversity, and searches for future exoplanets. In light of the many unknowns and assumptions involved, we recommend that these conclusions must be interpreted with due caution.« less
Atmospheric escape from the TRAPPIST-1 planets and implications for habitability

DOE PAGES

Dong, Chuanfei; Jin, Meng; Lingam, Manasvi; ...

2018-01-09

Here, the presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question of whether the seven Earth-sized planets transiting the recently discovered ultracool dwarf star TRAPPIST-1 are capable of retaining their atmospheres. To this effect, we carry out numerical simulations to characterize the stellar wind of TRAPPIST-1 and the atmospheric ion escape rates for all of the seven planets. We also estimate the escape rates analytically and demonstrate that they are in good agreement with the numerical results. We conclude that themore » outer planets of the TRAPPIST-1 system are capable of retaining their atmospheres over billion-year timescales. The consequences arising from our results are also explored in the context of abiogenesis, biodiversity, and searches for future exoplanets. In light of the many unknowns and assumptions involved, we recommend that these conclusions must be interpreted with due caution.« less
Atmospheric escape from the TRAPPIST-1 planets and implications for habitability

NASA Astrophysics Data System (ADS)

Dong, Chuanfei; Jin, Meng; Lingam, Manasvi; Airapetian, Vladimir S.; Ma, Yingjuan; van der Holst, Bart

2018-01-01

The presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question of whether the seven Earth-sized planets transiting the recently discovered ultracool dwarf star TRAPPIST-1 are capable of retaining their atmospheres. To this effect, we carry out numerical simulations to characterize the stellar wind of TRAPPIST-1 and the atmospheric ion escape rates for all of the seven planets. We also estimate the escape rates analytically and demonstrate that they are in good agreement with the numerical results. We conclude that the outer planets of the TRAPPIST-1 system are capable of retaining their atmospheres over billion-year timescales. The consequences arising from our results are also explored in the context of abiogenesis, biodiversity, and searches for future exoplanets. In light of the many unknowns and assumptions involved, we recommend that these conclusions must be interpreted with due caution.
Atmospheric escape from the TRAPPIST-1 planets and implications for habitability.

PubMed

Dong, Chuanfei; Jin, Meng; Lingam, Manasvi; Airapetian, Vladimir S; Ma, Yingjuan; van der Holst, Bart

2018-01-09

The presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question of whether the seven Earth-sized planets transiting the recently discovered ultracool dwarf star TRAPPIST-1 are capable of retaining their atmospheres. To this effect, we carry out numerical simulations to characterize the stellar wind of TRAPPIST-1 and the atmospheric ion escape rates for all of the seven planets. We also estimate the escape rates analytically and demonstrate that they are in good agreement with the numerical results. We conclude that the outer planets of the TRAPPIST-1 system are capable of retaining their atmospheres over billion-year timescales. The consequences arising from our results are also explored in the context of abiogenesis, biodiversity, and searches for future exoplanets. In light of the many unknowns and assumptions involved, we recommend that these conclusions must be interpreted with due caution.
Galactic cosmic ray-induced radiation dose on terrestrial exoplanets.

PubMed

Atri, Dimitra; Hariharan, B; Grießmeier, Jean-Mathias

2013-10-01

This past decade has seen tremendous advancements in the study of extrasolar planets. Observations are now made with increasing sophistication from both ground- and space-based instruments, and exoplanets are characterized with increasing precision. There is a class of particularly interesting exoplanets that reside in the habitable zone, which is defined as the area around a star where the planet is capable of supporting liquid water on its surface. Planetary systems around M dwarfs are considered to be prime candidates to search for life beyond the Solar System. Such planets are likely to be tidally locked and have close-in habitable zones. Theoretical calculations also suggest that close-in exoplanets are more likely to have weaker planetary magnetic fields, especially in the case of super-Earths. Such exoplanets are subjected to a high flux of galactic cosmic rays (GCRs) due to their weak magnetic moments. GCRs are energetic particles of astrophysical origin that strike the planetary atmosphere and produce secondary particles, including muons, which are highly penetrating. Some of these particles reach the planetary surface and contribute to the radiation dose. Along with the magnetic field, another factor governing the radiation dose is the depth of the planetary atmosphere. The higher the depth of the planetary atmosphere, the lower the flux of secondary particles will be on the surface. If the secondary particles are energetic enough, and their flux is sufficiently high, the radiation from muons can also impact the subsurface regions, such as in the case of Mars. If the radiation dose is too high, the chances of sustaining a long-term biosphere on the planet are very low. We have examined the dependence of the GCR-induced radiation dose on the strength of the planetary magnetic field and its atmospheric depth, and found that the latter is the decisive factor for the protection of a planetary biosphere.
Aeolian geomorphology from the global perspective

NASA Technical Reports Server (NTRS)

Greeley, R.

1985-01-01

Any planet or satellite having a dynamic atmosphere and a solid surface has the potential for experiencing aeolian (wind) processes. A survey of the Solar System shows at least four planetary objects which potentially meet these criteria: Earth, Mars, Venus, and possibly Titan, the largest satellite of Saturn. While the basic process is the same among these four objects, the movement of particles by the atmosphere, the aeolian environment is drastically different. It ranges from the hot (730 K), dense atmosphere of Venus to the extremely cold desert (218 K) environment of Mars where the atmospheric surface pressure is only approximately 7.5 mb. In considering aeolian processes in the planetary perspective, all three terrestrial planets share some common areas of attention for research, especially in regard to wind erosion and dust storms. Relevant properties of planetary objects potentially subject to aeolian processes are given in tabular form.
Pico Reentry Probes: Affordable Options for Reentry Measurements and Testing

NASA Technical Reports Server (NTRS)

Ailor, William H.; Kapoor, Vinod B.; Allen, Gay A., Jr.; Venkatapathy, Ethiraj; Arnold, James O.; Rasky, Daniel J.

2005-01-01

It is generally very costly to perform in-space and atmospheric entry experiments. This paper presents a new platform - the Pico Reentry Probe (PREP) - that we believe will make targeted flight-tests and planetary atmospheric probe science missions considerably more affordable. Small, lightweight, self-contained, it is designed as a "launch and forget" system, suitable for experiments that require no ongoing communication with the ground. It contains a data recorder, battery, transmitter, and user-customized instrumentation. Data recorded during reentry or space operations is returned at end-of-mission via transmission to Iridium satellites (in the case of earth-based operations) or a similar orbiting communication system for planetary missions. This paper discusses possible applications of this concept for Earth and Martian atmospheric entry science. Two well-known heritage aerodynamic shapes are considered as candidates for PREP: the shape developed for the Planetary Atmospheric Experiment Test (PAET) and that for the Deep Space II Mars Probe.
Algorithm for astronomical, point source, signal to noise ratio calculations

NASA Technical Reports Server (NTRS)

Jayroe, R. R.; Schroeder, D. J.

1984-01-01

An algorithm was developed to simulate the expected signal to noise ratios as a function of observation time in the charge coupled device detector plane of an optical telescope located outside the Earth's atmosphere for a signal star, and an optional secondary star, embedded in a uniform cosmic background. By choosing the appropriate input values, the expected point source signal to noise ratio can be computed for the Hubble Space Telescope using the Wide Field/Planetary Camera science instrument.
Challenges to Computational Aerothermodynamic Simulation and Validation for Planetary Entry Vehicle Analysis

DTIC Science & Technology

2010-04-01

than 0.6 metric tons. They have landed at low elevation sites (below 1 km Mars Orbiter Laser Altimeter ( MOLA )). All accepted a relatively large...Martian atmosphere, and small scale height of obstacles on the ground limit accessible landing sites to those below - 1.0km MOLA . So far the southern...landing to date is MER-Opportunity at Meridiani Planum (-1km MOLA ). Mars Science Lab (MSL) is attempting to develop an EDL system capable of delivering
The Whole Atmosphere Community Climate Model

NASA Astrophysics Data System (ADS)

Boville, B. A.; Garcia, R. R.; Sassi, F.; Kinnison, D.; Roble, R. G.

The Whole Atmosphere Community Climate Model (WACCM) is an upward exten- sion of the National Center for Atmospheric Research Community Climate System Model. WACCM simulates the atmosphere from the surface to the lower thermosphere (140 km) and includes both dynamical and chemical components. The salient points of the model formulation will be summarized and several aspects of its performance will be discussed. Comparison with observations indicates that WACCM produces re- alistic temperature and zonal wind distributions. Both the mean state and interannual variability will be summarized. Temperature inversions in the midlatitude mesosphere have been reported by several authors and are also found in WACCM. These inver- sions are formed primarily by planetary wave forcing, but the background state on which they form also requires gravity wave forcing. The response to sea surface temperature (SST) anomalies will be examined by com- paring simulations with observed SSTs for 1950-1998 to a simulation with clima- tological annual cycle of SSTs. The response to ENSO events is found to extend though the winter stratosphere and mesosphere and a signal is also found at the sum- mer mesopause. The experimental framework allows the ENSO signal to be isolated, because no other forcings are included (e.g. solar variability and volcanic eruptions) which complicate the observational record. The temperature and wind variations asso- ciated with ENSO are large enough to generate significant perturbations in the chem- ical composition of the middle atmosphere, which will also be discussed.
A solar escalator on Mars: Self-lifting of dust layers by radiative heating

NASA Astrophysics Data System (ADS)

Daerden, F.; Whiteway, J. A.; Neary, L.; Komguem, L.; Lemmon, M. T.; Heavens, N. G.; Cantor, B. A.; Hébrard, E.; Smith, M. D.

2015-09-01

Dust layers detected in the atmosphere of Mars by the light detection and ranging (LIDAR) instrument on the Phoenix Mars mission are explained using an atmospheric general circulation model. The layers were traced back to observed dust storm activity near the edge of the north polar ice cap where simulated surface winds exceeded the threshold for dust lifting by saltation. Heating of the atmospheric dust by solar radiation caused buoyant instability and mixing across the top of the planetary boundary layer (PBL). Differential advection by wind shear created detached dust layers above the PBL that ascended due to radiative heating and arrived at the Phoenix site at heights corresponding to the LIDAR observations. The self-lifting of the dust layers is similar to the "solar escalator" mechanism for aerosol layers in the Earth's stratosphere.
A Design Study of Onboard Navigation and Guidance During Aerocapture at Mars. M.S. Thesis

NASA Technical Reports Server (NTRS)

Fuhry, Douglas Paul

1988-01-01

The navigation and guidance of a high lift-to-drag ratio sample return vehicle during aerocapture at Mars are investigated. Emphasis is placed on integrated systems design, with guidance algorithm synthesis and analysis based on vehicle state and atmospheric density uncertainty estimates provided by the navigation system. The latter utilizes a Kalman filter for state vector estimation, with useful update information obtained through radar altimeter measurements and density altitude measurements based on IMU-measured drag acceleration. A three-phase guidance algorithm, featuring constant bank numeric predictor/corrector atmospheric capture and exit phases and an extended constant altitude cruise phase, is developed to provide controlled capture and depletion of orbital energy, orbital plane control, and exit apoapsis control. Integrated navigation and guidance systems performance are analyzed using a four degree-of-freedom computer simulation. The simulation environment includes an atmospheric density model with spatially correlated perturbations to provide realistic variations over the vehicle trajectory. Navigation filter initial conditions for the analysis are based on planetary approach optical navigation results. Results from a selection of test cases are presented to give insight into systems performance.
Space and planetary environment criteria guidelines for use in space vehicle development. Volume 1: 1982 revision

NASA Technical Reports Server (NTRS)

Smith, R. E. (Compiler); West, G. S. (Compiler)

1983-01-01

Guidelines on space and planetary environment criteria for use in space vehicle development are provided. Information is incorporated in the disciplinary areas of atmospheric and ionospheric properties, radiation, geomagnetic field, astrodynamic constants, and meteoroids for the Earth's atmosphere above 90 km, interplanetary space, and the atmosphere and surfaces (when available) of the Moon and the planets (other than Earth) of this solar system. The Sun, Terrestrial Space, the Moon, Mercury, Venus, and Mars are covered.
Data catalog series for space science and applications flight missions. Volume 1A: Brief descriptions of planetary and heliocentric spacecraft and investigations

NASA Technical Reports Server (NTRS)

Cameron, W. S. (Editor); Vostreys, R. W. (Editor)

1982-01-01

Planetary and heliocentric spacecraft, including planetary flybys and probes, are described. Imaging, particles and fields, ultraviolet, infrared, radio science and celestial mechanics, atmospheres, surface chemistry, biology, and polarization are discussed.
Scientific Value of a Saturn Atmospheric Probe Mission

NASA Technical Reports Server (NTRS)

Simon-Miller, A. A.; Lunine, J. I.; Atreya, S. K.; Spilker, T. R.; Coustenis, A.; Atkinson, D. H.

2012-01-01

Atmospheric entry probe mISSions to the giant planets can uniquely discriminate between competing theories of solar system formation and the origin and evolution of the giant planets and their atmospheres. This provides for important comparative studies of the gas and ice giants, and to provide a laboratory for studying the atmospheric chemistries, dynamics, and interiors of all the planets including Earth. The giant planets also represent a valuable link to extrasolar planetary systems. As outlined in the recent Planetary Decadal Survey, a Saturn Probe mission - with a shallow probe - ranks as a high priority for a New Frontiers class mission [1].

The Atmospheres of the Terrestrial Planets:Clues to the Origins and Early Evolution of Venus, Earth, and Mars

NASA Technical Reports Server (NTRS)

Baines, Kevin H.; Atreya, Sushil K.; Bullock, Mark A.; Grinspoon, David H,; Mahaffy, Paul; Russell, Christopher T.; Schubert, Gerald; Zahnle, Kevin

2015-01-01

We review the current state of knowledge of the origin and early evolution of the three largest terrestrial planets - Venus, Earth, and Mars - setting the stage for the chapters on comparative climatological processes to follow. We summarize current models of planetary formation, as revealed by studies of solid materials from Earth and meteorites from Mars. For Venus, we emphasize the known differences and similarities in planetary bulk properties and composition with Earth and Mars, focusing on key properties indicative of planetary formation and early evolution, particularly of the atmospheres of all three planets. We review the need for future in situ measurements for improving our understanding of the origin and evolution of the atmospheres of our planetary neighbors and Earth, and suggest the accuracies required of such new in situ data. Finally, we discuss the role new measurements of Mars and Venus have in understanding the state and evolution of planets found in the habitable zones of other stars.
Molecules of significance in planetary aeronomy

NASA Technical Reports Server (NTRS)

Mohan, H.

1979-01-01

This monograph is basically devoted to spectroscopic information of the molecules of planetary interest. Only those molecules have been dealt with which have been confirmed spectroscopically to be present in the atmosphere of major planets of our solar system and play an important role in the aeronomy of the respective planets. An introduction giving the general conditions of planets and their atmospheres including the gaseous molecules is given. Some typical planetary spectra is presented and supported with a discussion on some basic concepts of optical absorption and molecular parameters that are important to the study of planetary atmospheres. Quantities like dipole moments, transition probabilities, Einstein coefficients and line strengths, radiative life times, absorption cross sections, oscillator strengths, line widths and profiles, equivalent widths, growth curves, bond strengths, electronic transition moments, Franck-Condon factors and r-centroids, etc., are discussed. Spectroscopic information and relevant data of 6 diatomic (HF, HCL, CO, H2, O2, N2) and 6 polyatomic (CO2, N2), O3, HeO, NH3, CH4) molecules are presented.
Transient behavior of vertical scaling of mesoscale winds in the light of atmospheric turbulence transfer in and between synoptic and mesoscales

NASA Astrophysics Data System (ADS)

Barros, A. P.; Eghdami, M.

2017-12-01

High-resolution ( 1 km) numerical weather prediction models are capable of producing atmospheric spectra over synoptic and mesoscale ranges. Nogueira and Barros (2015) showed using high-resolution simulations in the Andes that the horizontal scale invariant behavior of atmospheric wind and water fields in the model is a process-dependent transient property that varies with the underlying dynamics. They found a sharp transition in the scaling parameters between non-convective and convective conditions. Spectral slopes around 2-2.3 arise under non-convective or very weak convective conditions, whereas in convective situations the transient scaling exponents remain under -5/3. Based on these results, Nogueira and Barros (2015) proposed a new sub-grid scale parameterization of clouds obtained from coarse resolution states alone. High Reynolds number direct numerical simulations of two-dimensional turbulence transfer shows that atmospheric flows involve concurrent direct (downscale) enstrophy transfer in the synoptic scales and inverse (upscale) kinetic energy transfer from the meso- to the synoptic-scales. In this study we use an analogy to investigate the transient behavior of kinetic energy spectra of winds over the Andes and Southern Appalachian Mountains representative of high and middle mountains, respectively. In the unstable conditions and particularly in the Planetary Boundary Layer (PBL) the spectral slopes approach -5/3 associated with the upscale KE turbulence transfer. However, in the stable conditions and above the planetary boundary layer, the spectra slopes approach steeper slopes about -3 associated with the downscale KE transfer. The underlying topography, surface roughness, diurnal heating and cooling and moist processes add to the complexity of the problem by introducing anisotropy and sources and sinks of energy. A comprehensive analysis and scaling of flow behavior conditional on stability regime for both KE and moist processes (total water, cloud water, rainfall) is necessary to elucidate scale-interactions among different processes.
Preservation of Biomarkers from Cyanobacteria Mixed with Mars-Like Regolith Under Simulated Martian Atmosphere and UV Flux.

PubMed

Baqué, Mickael; Verseux, Cyprien; Böttger, Ute; Rabbow, Elke; de Vera, Jean-Pierre Paul; Billi, Daniela

2016-06-01

The space mission EXPOSE-R2 launched on the 24th of July 2014 to the International Space Station is carrying the BIOMEX (BIOlogy and Mars EXperiment) experiment aimed at investigating the endurance of extremophiles and stability of biomolecules under space and Mars-like conditions. In order to prepare the analyses of the returned samples, ground-based simulations were carried out in Planetary and Space Simulation facilities. During the ground-based simulations, Chroococcidiopsis cells mixed with two Martian mineral analogues (phyllosilicatic and sulfatic Mars regolith simulants) were exposed to a Martian simulated atmosphere combined or not with UV irradiation corresponding to the dose received during a 1-year-exposure in low Earth orbit (or half a Martian year on Mars). Cell survival and preservation of potential biomarkers such as photosynthetic and photoprotective pigments or DNA were assessed by colony forming ability assays, confocal laser scanning microscopy, Raman spectroscopy and PCR-based assays. DNA and photoprotective pigments (carotenoids) were detectable after simulations of the space mission (570 MJ/m(2) of UV 200-400 nm irradiation and Martian simulated atmosphere), even though signals were attenuated by the treatment. The fluorescence signal from photosynthetic pigments was differently preserved after UV irradiation, depending on the thickness of the samples. UV irradiation caused a high background fluorescence of the Martian mineral analogues, as revealed by Raman spectroscopy. Further investigation will be needed to ensure unambiguous identification and operations of future Mars missions. However, a 3-month exposure to a Martian simulated atmosphere showed no significant damaging effect on the tested cyanobacterial biosignatures, pointing out the relevance of the latter for future investigations after the EXPOSE-R2 mission. Data gathered during the ground-based simulations will contribute to interpret results from space experiments and guide our search for life on Mars.
Preservation of Biomarkers from Cyanobacteria Mixed with MarsLike Regolith Under Simulated Martian Atmosphere and UV Flux

NASA Astrophysics Data System (ADS)

Baqué, Mickael; Verseux, Cyprien; Böttger, Ute; Rabbow, Elke; de Vera, Jean-Pierre Paul; Billi, Daniela

2016-06-01

The space mission EXPOSE-R2 launched on the 24th of July 2014 to the International Space Station is carrying the BIOMEX (BIOlogy and Mars EXperiment) experiment aimed at investigating the endurance of extremophiles and stability of biomolecules under space and Mars-like conditions. In order to prepare the analyses of the returned samples, ground-based simulations were carried out in Planetary and Space Simulation facilities. During the ground-based simulations, Chroococcidiopsis cells mixed with two Martian mineral analogues (phyllosilicatic and sulfatic Mars regolith simulants) were exposed to a Martian simulated atmosphere combined or not with UV irradiation corresponding to the dose received during a 1-year-exposure in low Earth orbit (or half a Martian year on Mars). Cell survival and preservation of potential biomarkers such as photosynthetic and photoprotective pigments or DNA were assessed by colony forming ability assays, confocal laser scanning microscopy, Raman spectroscopy and PCR-based assays. DNA and photoprotective pigments (carotenoids) were detectable after simulations of the space mission (570 MJ/m2 of UV 200-400 nm irradiation and Martian simulated atmosphere), even though signals were attenuated by the treatment. The fluorescence signal from photosynthetic pigments was differently preserved after UV irradiation, depending on the thickness of the samples. UV irradiation caused a high background fluorescence of the Martian mineral analogues, as revealed by Raman spectroscopy. Further investigation will be needed to ensure unambiguous identification and operations of future Mars missions. However, a 3-month exposure to a Martian simulated atmosphere showed no significant damaging effect on the tested cyanobacterial biosignatures, pointing out the relevance of the latter for future investigations after the EXPOSE-R2 mission. Data gathered during the ground-based simulations will contribute to interpret results from space experiments and guide our search for life on Mars.
Upcoming planetary missions and the applicability of high temperature superconductor bolometers

NASA Technical Reports Server (NTRS)

Brasunas, J.; Kunde, V.; Moseley, H.; Lakew, B.

1990-01-01

Past and present planetary exploration is briefly reviewed, and the planned 1996 Cassini mission to Saturn and Titan is examined. The CIRS experiment aboard Cassini, which will retrieve information on the atmospheres of Titan and Saturn, is discussed. Ongoing efforts to build a high-sensitivity, high-Tc bolometer that would greatly improve detection in Titan's atmosphere are addressed.
Science goals and concepts of a Saturn probe for the future L2/L3 ESA call

NASA Astrophysics Data System (ADS)

Schmider, F.-X.; Mousis, O.; Fletcher, L. N.; Altwegg, K.; André, N.; Blanc, M.; Coustenis, A.; Gautier, D.; Geppert, W. D.; Guillot, T.; Irwin, P.; Lebreton, J.-P.; Marty, B.; Sánchez-Lavega, A.; Waite, J. H.; Wurz, P.

2013-11-01

Comparative studies of the elemental enrichments and isotopic abundances measured on Saturn can provide unique insights into the processes at work within our planetary system and are related to the time and location of giant planet formation. In situ measurements via entry probes remain the only reliable, unambiguous method for determining the atmospheric composition from the thermosphere to the deep cloud-forming regions of their complex weather layers. Furthermore, in situ experiments can reveal the meteorological properties of planetary atmospheres to provide ``ground truth'' for orbital remote sensing. Following the orbital reconnaissance of the Galileo and Cassini spacecraft, and the single-point in situ measurement of the Galileo probe to Jupiter, we believe that an in situ measurement of Saturn's atmospheric composition should be an essential element of ESA's future cornerstone missions, providing the much-needed comparative planetology to reveal the origins of our outer planets. This quest for understanding the origins of our solar system and the nature of planetary atmospheres is in the heart of ESA's Cosmic Vision, and has vast implications for the origins of planetary systems around other stars.
Water Partitioning in Planetary Embryos and Protoplanets with Magma Oceans

NASA Astrophysics Data System (ADS)

Ikoma, M.; Elkins-Tanton, L.; Hamano, K.; Suckale, J.

2018-06-01

The water content of magma oceans is widely accepted as a key factor that determines whether a terrestrial planet is habitable. Water ocean mass is determined as a result not only of water delivery and loss, but also of water partitioning among several reservoirs. Here we review our current understanding of water partitioning among the atmosphere, magma ocean, and solid mantle of accreting planetary embryos and protoplanets just after giant collisions. Magma oceans are readily formed in planetary embryos and protoplanets in their accretion phase. Significant amounts of water are partitioned into magma oceans, provided the planetary building blocks are water-rich enough. Particularly important but still quite uncertain issues are how much water the planetary building blocks contain initially and how water goes out of the solidifying mantle and is finally degassed to the atmosphere. Constraints from both solar-system explorations and exoplanet observations and also from laboratory experiments are needed to resolve these issues.
Polarized scattered light from self-luminous exoplanets. Three-dimensional scattering radiative transfer with ARTES

NASA Astrophysics Data System (ADS)

Stolker, T.; Min, M.; Stam, D. M.; Mollière, P.; Dominik, C.; Waters, L. B. F. M.

2017-11-01

Context. Direct imaging has paved the way for atmospheric characterization of young and self-luminous gas giants. Scattering in a horizontally-inhomogeneous atmosphere causes the disk-integrated polarization of the thermal radiation to be linearly polarized, possibly detectable with the newest generation of high-contrast imaging instruments. Aims: We aim to investigate the effect of latitudinal and longitudinal cloud variations, circumplanetary disks, atmospheric oblateness, and cloud particle properties on the integrated degree and direction of polarization in the near-infrared. We want to understand how 3D atmospheric asymmetries affect the polarization signal in order to assess the potential of infrared polarimetry for direct imaging observations of planetary-mass companions. Methods: We have developed a three-dimensional Monte Carlo radiative transfer code (ARTES) for scattered light simulations in (exo)planetary atmospheres. The code is applicable to calculations of reflected light and thermal radiation in a spherical grid with a parameterized distribution of gas, clouds, hazes, and circumplanetary material. A gray atmosphere approximation is used for the thermal structure. Results: The disk-integrated degree of polarization of a horizontally-inhomogeneous atmosphere is maximal when the planet is flattened, the optical thickness of the equatorial clouds is large compared to the polar clouds, and the clouds are located at high altitude. For a flattened planet, the integrated polarization can both increase or decrease with respect to a spherical planet which depends on the horizontal distribution and optical thickness of the clouds. The direction of polarization can be either parallel or perpendicular to the projected direction of the rotation axis when clouds are zonally distributed. Rayleigh scattering by submicron-sized cloud particles will maximize the polarimetric signal whereas the integrated degree of polarization is significantly reduced with micron-sized cloud particles as a result of forward scattering. The presence of a cold or hot circumplanetary disk may also produce a detectable degree of polarization (≲1%) even with a uniform cloud layer in the atmosphere.
Preliminary studies on the planetary entry to Jupiter by aerocapture technique

NASA Astrophysics Data System (ADS)

Aso, Shigeru; Yasaka, Tetsuo; Hirayama, Hiroshi; Poetro, Ridanto Eko; Hatta, Shinji

2006-10-01

Preliminary studies on the planetary entry to Jupiter by aerocapture technique are studied in order to complete technological challenges to deliver scientific probe with low cost and smaller mass of the spacecraft to Jupiter. Jupiter aerocapture corridor determination based on maximum deceleration limit of 5g (lower corridor) and aerocapture capability (upper corridor) at Jupiter are carefully considered and calculated. The results show about 1700 m/s of saving velocity due to aerocapture could be possible in some cases for the spacecraft to be captured by Jovian gravitational field. However, the results also show that Jovian aerocapture is not available in some cases. Hence, careful selection is needed to realize Jovian aerocapture. Also the numerical simulation of aerodynamic heating to the spacecraft has been conducted. DSMC method is used for the simulation of flow fields around the spacecraft. The transient changes of drag due to Jovian atmosphere and total heat loads to the spacecraft are obtained. The results show that the estimated heat loads could be within allowable amount heat load when some ablation heat shield technique is applied.
Preliminary studies on the planetary entry to Jupiter by aerocapture technique

NASA Astrophysics Data System (ADS)

Aso, Shigeru; Yasaka, Tetsuo; Hirayama, Hiroshi; Eko Poetro, Ridanto; Hatta, Shinji

2003-11-01

Preliminary studies on the planetary entry to Jupiter by aerocapture technique are studied in order to complete technological challenges to deliver scientific probe with low cost and smaller mass of the spacecraft to Jupiter. Jupiter aerocapture corridor determination based on maximum deceleration limit of 5g (lower corridor) and aerocapture capability (upper corridor) at Jupiter are carefully considered and calculated. The results show about 1700 m/s of saving velocity due to aerocapture could be possible in some cases for the spacecraft to be captured by Jovian gravitational field. However, the results also show that Jovian aerocapture is not available in some cases. Hence, careful selection is needed to realise Jovian aerocapture. Also the numerical simulation of aerodynamic heating to the spacecraft has been conducted. DSMC method is used for the simulation of flow fields around the spacecraft. The transient changes of drag due to Jovian atmosphere and total heat loads to the spacecraft are obtained. The results show the estimated heat loads could be within allowable amount heat load when some ablation heat shield technique is applied.
Gas-Grain Simulation Facility (GGSF). Volume 2: Conceptual design definition

NASA Technical Reports Server (NTRS)

Zamel, James M.

1993-01-01

This document is Volume 2 of the Final Report for the Phase A Study of the Gas-Grain Simulation Facility (GGSF), and presents the GGSF Conceptual Design. It is a follow-on to the Volume 1 Facility Definition Study, NASA report CR 177606. The development of a conceptual design for a Space Station Freedom (SSF) facility that will be used for investigating particle interactions in varying environments, including various gas mixtures, pressures, and temperatures is delineated. It's not possible to study these experiments on earth due to the long reaction times associated with this type of phenomena, hence the need for extended periods of microgravity. The particle types will vary in composition (solids and liquids), sizes (from submicrons to centimeters), and concentrations (from single particles to 10(exp 10) per cubic centimeter). The results of the experiments pursued in the GGSF will benefit a variety of scientific inquiries. These investigations span such diverse topics as the formation of planets and planetary rings, cloud and haze processes in planetary atmospheres, the composition and structure of astrophysical objects, and the viability of airborne microbes (e.g., in a manned spacecraft).
Upper atmospheric planetary-wave and gravity-wave observations

NASA Technical Reports Server (NTRS)

Justus, C. G.; Woodrum, A.

1973-01-01

Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily-difference method, and results on the magnitude of atmospheric perturbations interpreted as gravity waves and planetary waves are presented. Traveling planetary-wave contributions in the 25-85 km range were found to have significant height and latitudinal variation. It was found that observed gravity-wave density perturbations and wind are related to one another in the manner predicted by gravity-wave theory. It was determined that, on the average, gravity-wave energy deposition or reflection occurs at all altitudes except the 55-75 km region of the mesosphere.
Planetary astronomy

NASA Technical Reports Server (NTRS)

Morrison, David; Hunten, Donald; Ahearn, Michael F.; Belton, Michael J. S.; Black, David; Brown, Robert A.; Brown, Robert Hamilton; Cochran, Anita L.; Cruikshank, Dale P.; Depater, Imke

1991-01-01

The authors profile the field of astronomy, identify some of the key scientific questions that can be addressed during the decade of the 1990's, and recommend several facilities that are critically important for answering these questions. Scientific opportunities for the 1990' are discussed. Areas discussed include protoplanetary disks, an inventory of the solar system, primitive material in the solar system, the dynamics of planetary atmospheres, planetary rings and ring dynamics, the composition and structure of the atmospheres of giant planets, the volcanoes of IO, and the mineralogy of the Martian surface. Critical technology developments, proposed projects and facilities, and recommendations for research and facilities are discussed.
Aerial Vehicle Surveys of other Planetary Atmospheres and Surfaces: Imaging, Remote-sensing, and Autonomy Technology Requirements

NASA Technical Reports Server (NTRS)

Young, Larry A.; Pisanich, Gregory; Ippolito, Corey; Alena, Rick

2005-01-01

The objective of this paper is to review the anticipated imaging and remote-sensing technology requirements for aerial vehicle survey missions to other planetary bodies in our Solar system that can support in-atmosphere flight. In the not too distant future such planetary aerial vehicle (a.k.a. aerial explorers) exploration missions will become feasible. Imaging and remote-sensing observations will be a key objective for these missions. Accordingly, it is imperative that optimal solutions in terms of imaging acquisition and real-time autonomous analysis of image data sets be developed for such vehicles.
Simulation of tracer dispersion from elevated and surface releases in complex terrain

NASA Astrophysics Data System (ADS)

Hernández, J. F.; Cremades, L.; Baldasano, J. M.

A new version of an advanced mesoscale dispersion modeling system for simulating passive air pollutant dispersion in the real atmospheric planetary boundary layer (PBL), is presented. The system comprises a diagnostic mass-consistent meteorological model and a Lagrangian particle dispersion model (LADISMO). The former version of LADISMO, developed according to Zannetti (Air pollution modelling, 1990), was based on the Monte Carlo technique and included calculation of higher-order moments of vertical random forcing for convective conditions. Its ability to simulate complex flow dispersion has been stated in a previous paper (Hernández et al. 1995, Atmospheric Environment, 29A, 1331-1341). The new version follows Thomson's scheme (1984, Q. Jl Roy. Met. Soc.110, 1107-1120). It is also based on Langevin equation and follows the ideas given by Brusasca et al. (1992, Atmospheric Environment26A, 707-723) and Anfossi et al. (1992, Nuovo Cemento 15c, 139-158). The model is used to simulate the dispersion and predict the ground level concentration (g.l.c.) of a tracer (SF 6) released from both an elevated source ( case a) and a ground level source ( case b) in a highly complex mountainous terrain during neutral and synoptically dominated conditions ( case a) and light and apparently stable conditions ( case b). The last case is considered as being a specially difficult task to simulate. In fact, few works have reported situations with valley drainage flows in complex terrains and real stable atmospheric conditions with weak winds. The model assumes that nearly calm situations associated to strong stability and air stagnation, make the lowest layers of PBL poorly diffusive (Brusasca et al., 1992, Atmospheric Environment26A, 707-723). Model results are verified against experimental data from Guardo-90 tracer experiments, an intensive field campaign conducted in the Carrion river valley (Northern Spain) to study atmospheric diffusion within a steep walled valley in mountainous terrain (Ibarra, 1992, Energia, No. 1, 74-85).
Zero potential vorticity envelopes for the zonal-mean velocity of the Venus/Titan atmospheres

NASA Technical Reports Server (NTRS)

Allison, Michael; Del Genio, Anthony D.; Zhou, Wei

1994-01-01

The diagnostic analysis of numerical simulations of the Venus/Titan wind regime reveals an overlooked constraint upon the latitudinal structure of their zonal-mean angular momentum. The numerical experiments, as well as the limited planetary observations, are approximately consistent with the hypothesis that within the latitudes bounded by the wind maxima the total Ertel potential vorticity associated with the zonal-mean motion is approximately well mixed with respect to the neutral equatorial value for a stable circulation. The implied latitudinal profile of angular momentum is of the form M equal to or less than M(sub e)(cos lambda)(exp 2/Ri), where lambda is the latitude and Ri the local Richardson number, generally intermediate between the two extremes of uniform angular momentum (Ri approaches infinity) and uniform angular velocity (Ri = 1). The full range of angular momentum profile variation appears to be realized within the observed meridional - vertical structure of the Venus atmosphere, at least crudely approaching the implied relationship between stratification and zonal velocity there. While not itself indicative of a particular eddy mechanism or specific to atmospheric superrotation, the zero potential vorticity (ZPV) constraint represents a limiting bound for the eddy - mean flow adjustment of a neutrally stable baroclinic circulation and may be usefully applied to the diagnostic analysis of future remote sounding and in situ measurements from planetary spacecraft.
Incorporation of the planetary boundary layer in atmospheric models

NASA Technical Reports Server (NTRS)

Moeng, Chin-Hoh; Wyngaard, John; Pielke, Roger; Krueger, Steve

1993-01-01

The topics discussed include the following: perspectives on planetary boundary layer (PBL) measurements; current problems of PBL parameterization in mesoscale models; and convective cloud-PBL interactions.
The Role of Remote Sensing Displays in Earth Climate and Planetary Atmospheric Research

NASA Technical Reports Server (NTRS)

DelGenio, Anthony D.; Hansen, James E. (Technical Monitor)

2001-01-01

The communities of scientists who study the Earth's climate and the atmospheres of the other planets barely overlap, but the types of questions they pose and the resulting implications for the use and interpretation of remote sensing data sets have much in common. Both seek to determine the characteristic behavior of three-dimensional fluids that also evolve in time. Climate researchers want to know how and why the general patterns that define our climate today might be different in the next century. Planetary scientists try to understand why circulation patterns and clouds on Mars, Venus, or Jupiter are different from those on Earth. Both disciplines must aggregate large amounts of data covering long time periods and several altitudes to have a representative picture of the rapidly changing atmosphere they are studying. This emphasis separates climate scientists from weather forecasters, who focus at any one time on a limited number of images. Likewise, it separates planetary atmosphere researchers from planetary geologists, who rely primarily on single images (or mosaics of images covering the globe) to study two-dimensional planetary surfaces that are mostly static over the duration of a spacecraft mission yet reveal dynamic processes acting over thousands to millions of years. Remote sensing displays are usually two-dimensional projections that capture an atmosphere at an instant in time. How scientists manipulate and display such data, how they interpret what they see, and how they thereby understand the physical processes that cause what they see, are the challenges I discuss in this chapter. I begin by discussing differences in how novices and experts in the field relate displays of data to the real world. This leads to a discussion of the use and abuse of image enhancement and color in remote sensing displays. I then show some examples of techniques used by scientists in climate and planetary research to both convey information and design research strategies using remote sensing displays.
STUDYING ATMOSPHERE-DOMINATED HOT JUPITER KEPLER PHASE CURVES: EVIDENCE THAT INHOMOGENEOUS ATMOSPHERIC REFLECTION IS COMMON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shporer, Avi; Hu, Renyu

2015-10-15

We identify three Kepler transiting planets, Kepler-7b, Kepler-12b, and Kepler-41b, whose orbital phase-folded light curves are dominated by planetary atmospheric processes including thermal emission and reflected light, while the impact of non-atmospheric (i.e., gravitational) processes, including beaming (Doppler boosting) and tidal ellipsoidal distortion, is negligible. Therefore, those systems allow a direct view of their atmospheres without being hampered by the approximations used in the inclusion of both atmospheric and non-atmospheric processes when modeling the phase-curve shape. We present here the analysis of Kepler-12b and Kepler-41b atmosphere based on their Kepler phase curve, while the analysis of Kepler-7b was already presentedmore » elsewhere. The model we used efficiently computes reflection and thermal emission contributions to the phase curve, including inhomogeneous atmospheric reflection due to longitudinally varying cloud coverage. We confirm Kepler-12b and Kepler-41b show a westward phase shift between the brightest region on the planetary surface and the substellar point, similar to Kepler-7b. We find that reflective clouds located on the west side of the substellar point can explain the phase shift. The existence of inhomogeneous atmospheric reflection in all three of our targets, selected due to their atmosphere-dominated Kepler phase curve, suggests this phenomenon is common. Therefore, it is also likely to be present in planetary phase curves that do not allow a direct view of the planetary atmosphere as they contain additional orbital processes. We discuss the implications of a bright-spot shift on the analysis of phase curves where both atmospheric and gravitational processes appear, including the mass discrepancy seen in some cases between the companion’s mass derived from the beaming and ellipsoidal photometric amplitudes. Finally, we discuss the potential detection of non-transiting but otherwise similar planets, whose mass is too small to show a gravitational photometric signal, but their atmosphere is reflective enough to show detectable phase modulations.« less

Modeling the interaction between plant canopies and the planetary boundary layer using a new 1D multi-layer soil- vegetation-atmosphere transfer (SVAT) scheme combined with a non-local turbulence closure model

NASA Astrophysics Data System (ADS)

Yetzer, Kenneth H.

A new one-dimensional (1D) soil-vegetation-atmospheric transport (SVAT) scheme is coupled to a nonlocal turbulence closure model in order to simulate the interactions between a forested canopy and the planetary boundary layer. The SVAT consists of mechanistic models for both physiological (photosynthesis, stomatal conductance and soil/root and bole respiration) and micrometeorological (radiative transfer and surface energy exchanges) processes. The turbulence closure model is a first-order, nonlocal turbulence closure called transilient turbulence theory (Stull, 1993; Inclan et al., 1995) which includes the effects of form drag, wake turbulence, and interference to vertical mixing by the plant elements. The submodel that accounts for radiative transfer inside the forest has been taken from Norman (1979) and Baldocchi (1989). It includes the effect of varying mean leaf inclination angle with height and it also accounts for leaf clumping The photosynthesis submodel is taken from Nikolov and others (1995). It accounts for both differences between shaded and sunlit leaves and the variation of photosynthetic capacity with height. The model was tested with data obtained from a deciduous forest in Pennsylvania. The results show reasonable agreement with the observations. They also demonstrate the model's ability to simulate phenomena that is characteristic of tall canopies like forests, including counter gradient-fluxes and local wind speed maxima in the trunk space.
A CHEMICAL KINETICS NETWORK FOR LIGHTNING AND LIFE IN PLANETARY ATMOSPHERES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rimmer, P. B.; Helling, Ch, E-mail: pr33@st-andrews.ac.uk

2016-05-01

There are many open questions about prebiotic chemistry in both planetary and exoplanetary environments. The increasing number of known exoplanets and other ultra-cool, substellar objects has propelled the desire to detect life and prebiotic chemistry outside the solar system. We present an ion–neutral chemical network constructed from scratch, Stand2015, that treats hydrogen, nitrogen, carbon, and oxygen chemistry accurately within a temperature range between 100 and 30,000 K. Formation pathways for glycine and other organic molecules are included. The network is complete up to H6C2N2O3. Stand2015 is successfully tested against atmospheric chemistry models for HD 209458b, Jupiter, and the present-day Earth usingmore » a simple one-dimensional photochemistry/diffusion code. Our results for the early Earth agree with those of Kasting for CO{sub 2}, H{sub 2}, CO, and O{sub 2}, but do not agree for water and atomic oxygen. We use the network to simulate an experiment where varied chemical initial conditions are irradiated by UV light. The result from our simulation is that more glycine is produced when more ammonia and methane is present. Very little glycine is produced in the absence of any molecular nitrogen and oxygen. This suggests that the production of glycine is inhibited if a gas is too strongly reducing. Possible applications and limitations of the chemical kinetics network are also discussed.« less
Planetary atmospheric physics and solar physics research

NASA Technical Reports Server (NTRS)

1973-01-01

An overview is presented on current and planned research activities in the major areas of solar physics, planetary atmospheres, and space astronomy. The approach to these unsolved problems involves experimental techniques, theoretical analysis, and the use of computers to analyze the data from space experiments. The point is made that the research program is characterized by each activity interacting with the other activities in the laboratory.
The importance of dunes on a variety of planetary surfaces

USGS Publications Warehouse

Titus, Timothy N.; Zimbelman, James R.; Radebaugh, Jani

2015-01-01

Scientists observe aeolian bed forms, or dune-like structures, throughout the solar system in a range of locations, from bodies with only transient atmospheres, such as comets, to places with thick atmospheres, such as Venus and the Earth’s ocean floor. Determining the source of sand and the different dune formations that result are thus important to understanding solar system and planetary evolution.
Planetary Research Center. [astronomical photography of planetary surfaces and atmospheres

NASA Technical Reports Server (NTRS)

Baum, W. A.; Millis, R. L.; Bowell, E. L. G.

1974-01-01

Extensive Earth-based photography of Mars, Jupiter, and Venus is presented which monitors the atmospheric and/or surface changes that take place day to day. Color pictures are included of the 1973 dust storm on Mars, showing the daily cycle of the storm's regeneration. Martian topography, and the progress of the storm is examined. Areas most affected by the storm are summarized.
Teaching Planetary Sciences at the Universidad del País Vasco in Spain: The Aula Espazio Gela and its Master in Space Science and Technology

NASA Astrophysics Data System (ADS)

Hueso, R.; Sanchez-Lavega, A.; Pérez-Hoyos, S.

2011-12-01

Planetary science is a highly multidisciplinary field traditionally associated to Astronomy, Physics or Earth Sciences Departments. Spanish universities do not generally offer planetary sciences courses but some departments give courses associated to studies on Astronomy or Geology. We show a different perspective obtained at the Engeneering School at the Universidad del País Vasco in Bilbao, Spain, which offers a Master in Space Science and Technology to graduates in Engineering or Physics. Here we detail the experience acquired in two years of this master which offers several planetary science courses: Solar System Physics, Astronomy, Planetary Atmospheres & Space Weather together with more technical courses. The university also owns an urban observatory in the Engineering School which is used for practical exercises and student projects. The planetary science courses have also resulted in motivating part of the students to do their master thesis in scientific subjects in planetary sciences. Since the students have very different backgrounds their master theses have been quite different: From writing open software tools to detect bolides in video observations of Jupiter atmosphere to the photometric calibration and scientific use or their own Jupiter and Saturn images or the study of atmospheric motions of the Venus' South Polar Vortex using data from the Venus Express spacecraft. As a result of this interaction with the students some of them have been engaged to initiate Ph.D.s in planetary sciences enlarging a relative small field in Spain. Acknowledgements: The Master in Space Science and Technology is offered by the Aula Espazio Gela at the Universidad del País Vasco Engineer School in Bilbao, Spain and is funded by Diputación Foral de Bizkaia.
Energetic Neutral Atom Emissions From Venus: VEX Observations and Theoretical Modeling

NASA Technical Reports Server (NTRS)

Fok, M.-C.; Galli, A.; Tanaka, T.; Moore, T. E.; Wurz, P.; Holmstrom, M.

2007-01-01

Venus has almost no intrinsic magnetic field to shield itself from its surrounding environment. The solar wind thus directly interacts with the planetary ionosphere and atmosphere. One of the by-products of this close encounter is the production of energetic neutral atom (ENA) emissions. Theoretical studies have shown that significant amount of ENAs are emanated from the planet. The launch of the Venus Express (VEX) in 2005 provided the first light ever of the Venus ENA emissions. The observed ENA flux level and structure are in pretty good agreement with the theoretical studies. In this paper, we present VEX ENA data and the comparison with numerical simulations. We seek to understand the solar wind interaction with the planet and the impacts on its atmospheres.
Laboratory Simulations of Haze Formation in the Atmospheres of Super-Earths and Mini-Neptunes: Particle Color and Size Distribution

NASA Astrophysics Data System (ADS)

He, Chao; Hörst, Sarah M.; Lewis, Nikole K.; Yu, Xinting; Moses, Julianne I.; Kempton, Eliza M.-R.; McGuiggan, Patricia; Morley, Caroline V.; Valenti, Jeff A.; Vuitton, Véronique

2018-03-01

Super-Earths and mini-Neptunes are the most abundant types of planets among the ∼3500 confirmed exoplanets, and are expected to exhibit a wide variety of atmospheric compositions. Recent transmission spectra of super-Earths and mini-Neptunes have demonstrated the possibility that exoplanets have haze/cloud layers at high altitudes in their atmospheres. However, the compositions, size distributions, and optical properties of these particles in exoplanet atmospheres are poorly understood. Here, we present the results of experimental laboratory investigations of photochemical haze formation within a range of planetary atmospheric conditions, as well as observations of the color and size of produced haze particles. We find that atmospheric temperature and metallicity strongly affect particle color and size, thus altering the particles’ optical properties (e.g., absorptivity, scattering, etc.); on a larger scale, this affects the atmospheric and surface temperature of the exoplanets, and their potential habitability. Our results provide constraints on haze formation and particle properties that can serve as critical inputs for exoplanet atmosphere modeling, and guide future observations of super-Earths and mini-Neptunes with the Transiting Exoplanet Survey Satellite, the James Webb Space Telescope, and the Wide-Field Infrared Survey Telescope.
Simulations of Global Flows in Io’s Rarefied Atmosphere

NASA Astrophysics Data System (ADS)

Hoey, William A.; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M.; Walker, A. C.

2013-10-01

The sulfur-rich Ionian atmosphere is populated through a number of mechanisms, the most notable of which include sublimation from insolated surface frost deposits, material sputtering due to the impact of energetic ions from the Jovian plasma torus, and plume emission related to volcanic activity. While local flows are collisional at low altitudes on portions of the moon’s dayside, densities rapidly tend toward the free-molecular limit with altitude, necessitating non-continuum (rarefied gas dynamic) modeling and analysis. While recent work has modestly constrained the relative contributions of sputtering, sublimation, and volcanism to Io’s atmosphere, dynamic wind patterns driven by dayside sublimation and nightside condensation remain poorly understood. This work moves toward the explanation of mid-infrared observations that indicate an apparent super-rotating wind in Io’s atmosphere. In the present work, the Direct Simulation Monte Carlo method is employed in the modeling of Io’s rarefied atmosphere; simulations are computed in parallel, on a three-dimensional domain that spans the moon’s entire surface and extends hundreds of kilometers vertically, into the exobase. A wide range of physical phenomena have been incorporated into the atmospheric model, including: [1] the effects of planetary rotation; [2] surface temperature, surface frost inhomogeneity, and thermal inertia; [3] plasma heating and sputtering; [4] gas plumes from superimposed volcanic hot spots; and [5] multi-species chemistry. Furthermore, this work improves upon previous efforts by correcting for non-inertial effects in a moon-fixed reference frame. The influence of such effects on the development of global flow patterns and cyclonic wind is analyzed. The case in which Io transits Jupiter is considered, with the anti-Jovian hemisphere as the dayside. We predict that a circumlunar flow develops that is asymmetric about the subsolar point, and drives atmosphere from the warmer, dayside hemisphere toward the colder nightside. The resultant flow patterns, column densities, species concentrations, and temperatures are discussed in relation to previous simulations of Io in a pre-eclipse configuration. This research is supported via NASA-PATM.
Mars Science Laboratory Entry, Descent, and Landing Trajectory and Atmosphere Reconstruction

NASA Technical Reports Server (NTRS)

Karlgaard, Christopher D.; Kutty, Prasad; Schoenenberer, Mark; Shidner, Jeremy D.

2013-01-01

On August 5th 2012, The Mars Science Laboratory entry vehicle successfully entered Mars atmosphere and landed the Curiosity rover on its surface. A Kalman filter approach has been implemented to reconstruct the entry, descent, and landing trajectory based on all available data. The data sources considered in the Kalman filtering approach include the inertial measurement unit accelerations and angular rates, the terrain descent sensor, the measured landing site, orbit determination solutions for the initial conditions, and a new set of instrumentation for planetary entry reconstruction consisting of forebody pressure sensors, known as the Mars Entry Atmospheric Data System. These pressure measurements are unique for planetary entry, descent, and landing reconstruction as they enable a reconstruction of the freestream atmospheric conditions without any prior assumptions being made on the vehicle aerodynamics. Moreover, the processing of these pressure measurements in the Kalman filter approach enables the identification of atmospheric winds, which has not been accomplished in past planetary entry reconstructions. This separation of atmosphere and aerodynamics allows for aerodynamic model reconciliation and uncertainty quantification, which directly impacts future missions. This paper describes the mathematical formulation of the Kalman filtering approach, a summary of data sources and preprocessing activities, and results of the reconstruction.
Atmospheric Convective Organization: Self-Organized Criticality or Homeostasis?

NASA Astrophysics Data System (ADS)

Yano, Jun-Ichi

2015-04-01

Atmospheric convection has a tendency organized on a hierarchy of scales ranging from the mesoscale to the planetary scales, with the latter especially manifested by the Madden-Julian oscillation. The present talk examines two major possible mechanisms of self-organization identified in wider literature from a phenomenological thermodynamic point of view by analysing a planetary-scale cloud-resolving model simulation. The first mechanism is self-organized criticality. A saturation tendency of precipitation rate with the increasing column-integrated water, reminiscence of critical phenomena, indicates self-organized criticality. The second is a self-regulation mechanism that is known as homeostasis in biology. A thermodynamic argument suggests that such self-regulation maintains the column-integrated water below a threshold by increasing the precipitation rate. Previous analyses of both observational data as well as cloud-resolving model (CRM) experiments give mixed results. A satellite data analysis suggests self-organized criticality. Some observational data as well as CRM experiments support homeostasis. Other analyses point to a combination of these two interpretations. In this study, a CRM experiment over a planetary-scale domain with a constant sea-surface temperature is analyzed. This analysis shows that the relation between the column-integrated total water and precipitation suggests self-organized criticality, whereas the one between the column-integrated water vapor and precipitation suggests homeostasis. The concurrent presence of these two mechanisms are further elaborated by detailed statistical and budget analyses. These statistics are scale invariant, reflecting a spatial scaling of precipitation processes. These self-organization mechanisms are most likely be best theoretically understood by the energy cycle of the convective systems consisting of the kinetic energy and the cloud-work function. The author has already investigated the behavior of this cycle system under a zero-dimensional configuration. Preliminary simulations of this cycle system over a two-dimensional domain will be presented.
Models of Mars' atmosphere (1974)

NASA Technical Reports Server (NTRS)

1974-01-01

Atmospheric models for support of design and mission planning of space vehicles that are to orbit the planet Mars, enter its atmosphere, or land on the surface are presented. Quantitative data for the Martian atmosphere were obtained from Earth-base observations and from spacecraft that have orbited Mars or passed within several planetary radii. These data were used in conjunction with existing theories of planetary atmospheres to predict other characteristics of the Martian atmosphere. Earth-based observations provided information on the composition, temperature, and optical properties of Mars with rather coarse spatial resolution, whereas spacecraft measurements yielded data on composition, temperature, pressure, density, and atmospheric structure with moderately good spatial resolution. The models provide the temperature, pressure, and density profiles required to perform basic aerodynamic analyses. The profiles are supplemented by computed values of viscosity, specific heat, and speed of sound.
Planetary Differentiation by Aerial Metasomatism

NASA Astrophysics Data System (ADS)

Baker, D. R.

2018-05-01

Dissolution of surficial rocks will occur on planetary bodies with steam atmospheres. Although the amount of dissolved material is small, metasomatism of chondritic compositions produces siliceous crustal materials and enriches residual rocks.
Atmospheric Environments for Entry, Descent and Landing (EDL)

NASA Technical Reports Server (NTRS)

Justus, Carl G.; Braun, Robert D.

2007-01-01

Scientific measurements of atmospheric properties have been made by a wide variety of planetary flyby missions, orbiters, and landers. Although landers can make in-situ observations of near-surface atmospheric conditions (and can collect atmospheric data during their entry phase), the vast majority of data on planetary atmospheres has been collected by remote sensing techniques from flyby and orbiter spacecraft (and to some extent by Earth-based remote sensing). Many of these remote sensing observations (made over a variety of spectral ranges), consist of vertical profiles of atmospheric temperature as a function of atmospheric pressure level. While these measurements are of great interest to atmospheric scientists and modelers of planetary atmospheres, the primary interest for engineers designing entry descent and landing (EDL) systems is information about atmospheric density as a function of geometric altitude. Fortunately, as described in in this paper, it is possible to use a combination of the gas-law relation and the hydrostatic balance relation to convert temperature-versus-pressure, scientific observations into density-versus-altitude data for use in engineering applications. The following section provides a brief introduction to atmospheric thermodynamics, as well as constituents, and winds for EDL. It also gives methodology for using atmospheric information to do "back-of-the-envelope" calculations of various EDL aeroheating parameters, including peak deceleration rate ("g-load"), peak convective heat rate. and total heat load on EDL spacecraft thermal protection systems. Brief information is also provided about atmospheric variations and perturbations for EDL guidance and control issues, and atmospheric issues for EDL parachute systems. Subsequent sections give details of the atmospheric environments for five destinations for possible EDL missions: Venus. Earth. Mars, Saturn, and Titan. Specific atmospheric information is provided for these destinations, and example results are presented for the "back-of-the-envelope" calculations mentioned above.
Orbit-spin coupling and the circulation of the Martian atmosphere

NASA Astrophysics Data System (ADS)

Shirley, James H.

2017-07-01

The physical origins of the observed interannual variability of weather and climate on Mars are poorly understood. In this paper we introduce a deterministic physical mechanism that may account for much of the variability of the circulation of the Mars atmosphere on seasonal and longer timescales. We focus on a possible coupling between the planetary orbital angular momentum and the angular momentum of the planetary rotation. We suspect that the planetary atmosphere may participate in an exchange of momentum between these two reservoirs. Nontrivial changes in the circulation of the atmosphere are likely to occur, as the atmospheric system gains and loses angular momentum, during this exchange. We derive a coupling expression linking orbital and rotational motions that produces an acceleration field varying with position and with time on and within a subject body. The spatially and temporally varying accelerations may interfere constructively or destructively with large-scale flows of geophysical fluids that are established and maintained by other means. This physical hypothesis predicts cycles of intensification and relaxation of circulatory flows of atmospheres on seasonal and longer timescales that are largely independent of solar forcing. The predictions of this hypothesis may be tested through numerical modeling. Examples from investigations of the atmospheric circulation of Mars are provided to illustrate qualitative features and quantitative aspects of the coupling mechanism proposed.
Exhaust-gas measurements from NASAs HYMETS arc jet.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Paul Albert

Arc-jet wind tunnels produce conditions simulating high-altitude hypersonic flight such as occurs upon entry of space craft into planetary atmospheres. They have traditionally been used to study flight in Earth's atmosphere, which consists mostly of nitrogen and oxygen. NASA is presently using arc jets to study entry into Mars' atmosphere, which consists of carbon dioxide and nitrogen. In both cases, a wide variety of chemical reactions take place among the gas constituents and with test articles placed in the flow. In support of those studies, we made measurements using a residual gas analyzer (RGA) that sampled the exhaust stream ofmore » a NASA arc jet. The experiments were conducted at the HYMETS arc jet (Hypersonic Materials Environmental Test System) located at the NASA Langley Research Center, Hampton, VA. This report describes our RGA measurements, which are intended to be used for model validation in combination with similar measurements on other systems.« less
Planetary atmospheres minor species sensor balloon flight test to near space

NASA Astrophysics Data System (ADS)

Peale, Robert E.; Fredricksen, Christopher J.; Muraviev, Andrei V.; Maukonen, Douglas; Quddusi, Hajrah M.; Calhoun, Seth; Colwell, Joshua E.; Lachenmeier, Timothy A.; Dewey, Russell G.; Stern, Alan; Padilla, Sebastian; Bode, Rolfe

2015-05-01

The Planetary Atmospheres Minor Species Sensor (PAMSS) is an intracavity laser absorption spectrometer that uses a mid-infrared quantum cascade laser in an open external cavity for sensing ultra-trace gases with parts-per-billion sensitivity. PAMSS was flown on a balloon by Near Space Corporation from Madras OR to 30 km on 17 July 2014. Based on lessons learned, it was modified and was flown a second time to 32 km by World View Enterprises from Pinal AirPark AZ on 8 March 2015. Successes included continuous operation and survival of software, electronics, optics, and optical alignment during extreme conditions and a rough landing. Operation of PAMSS in the relevant environment of near space has significantly elevated its Technical Readiness Level for trace-gas sensing with potential for planetary and atmospheric science in harsh environments.
Analytical design of sensors for measuring during terminal phase of atmospheric temperature planetary entry

NASA Technical Reports Server (NTRS)

Millard, J. P.; Green, M. J.; Sommer, S. C.

1972-01-01

An analytical study was conducted to develop a sensor for measuring the temperature of a planetary atmosphere from an entry vehicle traveling at supersonic speeds and having a detached shock. Such a sensor has been used in the Planetary Atmosphere Experiments Test Probe (PAET) mission and is planned for the Viking-Mars mission. The study specifically considered butt-welded thermocouple sensors stretched between two support posts; however, the factors considered are sufficiently general to apply to other sensors as well. This study included: (1) an investigation of the relation between sensor-measured temperature and free-stream conditions; (2) an evaluation of the effects of extraneous sources of heat; (3) the development of a computer program for evaluating sensor response during entry; and (4) a parametric study of sensor design characteristics.
Interannual Variability In the Atmospheric CO2 Rectification Over Boreal Forests Based On A Coupled Ecosystem-Atmosphere Model

NASA Astrophysics Data System (ADS)

Chen, B.; Chen, J. M.; Worthy, D.

2004-05-01

Ecosystem CO2 exchange and the planetary boundary layer (PBL) are correlated diurnally and seasonally. The simulation of this atmospheric rectifier effect is important in understanding the global CO2 distribution pattern. A 12-year (1990-1996, 1999-2003), continuous CO2 measurement record from Fraserdale, Ontario (located ~150 km north of Timmons), along with a coupled Vertical Diffusion Scheme (VDS) and ecosystem model (Boreal Ecosystem Productivity Simulator, BEPS), is used to investigate the interannual variability in this effect over a boreal forest region. The coupled model performed well in simulating CO2 vertical diffusion processes. Simulated annual atmospheric rectifier effects, (including seasonal and diurnal), quantified as the variation in the mean CO2 concentration from the surface to the top of the PBL, varied from 2.8 to 4.1 ppm, even though the modeled seasonal variations in the PBL depth were similar throughout the 12-year period. The differences in the interannual rectifier effect primarily resulted from changes in the biospheric CO2 uptake and heterotrophic respiration. Correlations in the year-to year variations of the CO2 rectification were found with mean annual air temperatures, simulated gross primary productivity (GPP) and heterotrophic respiration (Rh) (r2=0.5, 0.46, 0.42, respectively). A small increasing trend in the CO2 rectification was also observed. The year-to-year variation in the vertical distribution of the monthly mean CO2 mixing ratios (reflecting differences in the diurnal rectifier effect) was related to interannual climate variability, however, the seasonal rectifier effects were found to be more sensitive to climate variability than the diurnal rectifier effects.
Dynamics of large scale impacts on Venus and Earth

NASA Technical Reports Server (NTRS)

Okeefe, John D.; Ahrens, Thomas J.

1993-01-01

Large scale impacts are a key aspect of the accretion and growth of the planets, the evolution of their atmospheres, and the viability of their life forms. We have performed an extensive series of numerical calculations that examined the mechanics of impacts over a broad range of conditions and are now extending these to account for the effects of the planetary atmosphere. We have examined the effects of large scale impacts in which the trapping and compression of an atmosphere during impact is a significant factor in the transfer of energy to the atmosphere. The various energy transfer regimes and where conventional drag and trapping and subsequent compression of atmosphere between the bolide and planetary surface are significant are shown.

Rocky Planetary Debris Around Young WDs

NASA Astrophysics Data System (ADS)

Gaensicke, B.

2014-04-01

The vast majority of all known planet host stars, including the Sun, will eventually evolve into red giants and finally end their lives as white dwarfs: extremely dense Earth-sized stellar embers. Only close-in planets will be devoured during the red-giant phase. In the solar system, Mars, the asteroid belt, and all the giant planets will escape evaporation, and the same is true for many of the known exo-planets. It is hence certain that a significant fraction of the known white dwarfs were once host stars to planets, and it is very likely that many of them still have remnants of planetary systems. The detection of metals in the atmospheres of white dwarfs is the unmistakable signpost of such evolved planetary systems. The strong surface gravity of white dwarfs causes metals to sink out of the atmosphere on time-scales much shorter than their cooling ages, leading unavoidably to pristine H/He atmospheres. Therefore any metals detected in the atmosphere of a white dwarf imply recent or ongoing accretion of planetary debris. In fact, planetary debris is also detected as circumstellar dust and gas around a number of white dwarfs. These debris disks are formed from the tidal disruption of asteroids or Kuiper belt-like objects, stirred up by left-over planets, and are subsequently accreted onto the white dwarf, imprinting their abundance pattern into its atmosphere. Determining the photospheric abundances of debris-polluted white dwarfs is hence entirely analogue to the use of meteorites, "rocks that fell from the sky", for measuring the abundances of planetary material in the solar system. I will briefly review this new field of exo-planet science, and then focus on the results of a large, unbiased COS snapshot survey of relatively young ( 20-100Myr) white dwarfs that we carried out in Cycle 18/19. * At least 30% of all white dwarfs in our sample are accreting planetary debris, and that fraction may be as high as 50%. * In most cases where debris pollution is detected, the low C/Si ratio demonstrates that the planetary material is of rocky nature. * None of the 9 systems where we measure the C/O ratio shows evidence for carbon-dominated chemistry, implying that "carbon planets" are not common. * In the most polluted white dwarfs, we measure the debris abundances of up to 11 elements, enabling a detailed comparison between the chemistry of exo-planetary material with that of solar system meteorites. We find that the exo-planetary debris shares many characteristics of solar-system material, i.e. a wide spread in the relative abundances of Mg, Fe, Si, and O, a constant Al/Ca ratio, and evidence for differentiation in the form of Fe over-abundances All of the above is suggestive that thermal and collisional processing of planetary material in those systems might have been similar to that in the solar system.
An overview on Bernese projects in planetary geodesy and deep-space orbit determination

NASA Astrophysics Data System (ADS)

Bertone, S.; Jaeggi, A.; Arnold, D.; Girardin, V.; Hosseini, A.; Desprats, W.; Inamdar, J.

2017-12-01

The Astronomical Institute of the University of Bern (AIUB) is still a rather new player in the field of planetary geodesy and orbit determination using deep-space radio-tracking data. Nevertheless, our latest developments in the in-house Bernese GNSS Software (BSW) and the experience gained with the processing of GRAIL data opened the way to many research and collaboration opportunities. In this presentation, we give an overview on our current projects and advances, as well as on our ongoing collaborations. We will present closed-loop simulations of BepiColombo Mercury Planetary Orbiter (MPO) Doppler and altimetry data, including realistic noise models. We use our newly established simulation environment in the BSW and calibration results of the BepiColombo Laser Altimeter (BELA) performed by the Space Research and Planetary Sciences division of the University of Bern. The ultimate goal of these activities is to test different realistic scenarios of the BELA in-orbit performance to improve the recovery of Mercury geodesy and geophysical parameters. We recently started to work on the combined re-processing of all historical missions to Venus to improve their orbits and hence Venus gravity field using new available data (e.g., new atmospheric models), processing tools and techniques and computational power. We shall present our latest advances in processing Magellan data and towards a rigorous solution for the Venus gravity field, e.g., avoiding a step-wise processing as used by Konopliv et al. (1999). The AIUB is currently involved in the Joint Europa Mission proposal. In this framework we present our results for a realistic orbit and gravity field recovery based on simulated Doppler radio-tracking data from the planned scenario of a three months low altitude polar orbit around Europa. We describe our efforts in adapting our simulation tools to the peculiar environment of the Jovian satellite system. Eventually we briefly present the highlights of our latest results in Moon geodesy, including our latest gravity field and tidal parameters solutions from GRAIL data. A separate presentation will be dedicated to detail our Moon-related activities within this session.
Innovative Technique for Noise Reduction in Spacecraft Doppler Tracking for Planetary Interior Studies

NASA Astrophysics Data System (ADS)

Notaro, V.; Armstrong, J. W.; Asmar, S.; Di Ruscio, A.; Iess, L.; Mariani, M., Jr.

2017-12-01

Precise measurements of spacecraft range rate, enabled by two-way microwave links, are used in radio science experiments for planetary geodesy including the determination of planetary gravitational fields for the purpose of modeling the interior structure. The final accuracies in the estimated gravity harmonic coefficients depend almost linearly on the Doppler noise in the link. We ran simulations to evaluate the accuracy improvement attainable in the estimation of the gravity harmonic coefficients of Venus (with a representative orbiter) and Mercury (with the BepiColombo spacecraft), using our proposed innovative noise-cancellation technique. We showed how the use of an additional, smaller and stiffer, receiving-only antenna could reduce the leading noise sources in a Ka-band two-way link such as tropospheric and antenna mechanical noises. This is achieved through a suitable linear combination (LC) of Doppler observables collected at the two antennas at different times. In our simulations, we considered a two-way link either from NASA's DSS 25 antenna in California or from ESA's DSA-3 antenna in Malargüe (Argentina). Moreover, we selected the 12-m Atacama Pathfinder EXperiment (APEX) in Chile as the three-way antenna and developed its tropospheric noise model using available atmospheric data and mechanical stability specifications. For an 8-hour Venus orbiter tracking pass in Chajnantor's winter/night conditions, the accuracy of the simulated LC Doppler observable at 10-s integration time is 6 mm/s, to be compared to 23 mm/s for the two-way link. For BepiColombo, we obtained 16.5 mm/s and 35 mm/s, respectively for the LC and two-way links. The benefits are even larger at longer time scales. Numerical simulations indicate that such noise reduction would provide significant improvements in the determination of Venus's and Mercury's gravity field coefficients. If implemented, this noise-reducing technique will be valuable for planetary geodesy missions, where the accuracy in the estimation of high-order gravity harmonic coefficients is limited by tropospheric and antenna mechanical noises that are difficult to reduce at short integration times. Benefits are however expected in all precision radio science experiments with deep space probes.
Construction of Hierarchical Models for Fluid Dynamics in Earth and Planetary Sciences : DCMODEL project

NASA Astrophysics Data System (ADS)

Takahashi, Y. O.; Takehiro, S.; Sugiyama, K.; Odaka, M.; Ishiwatari, M.; Sasaki, Y.; Nishizawa, S.; Ishioka, K.; Nakajima, K.; Hayashi, Y.

2012-12-01

Toward the understanding of fluid motions of planetary atmospheres and planetary interiors by performing multiple numerical experiments with multiple models, we are now proceeding ``dcmodel project'', where a series of hierarchical numerical models with various complexity is developed and maintained. In ``dcmodel project'', a series of the numerical models are developed taking care of the following points: 1) a common ``style'' of program codes assuring readability of the software, 2) open source codes of the models to the public, 3) scalability of the models assuring execution on various scales of computational resources, 4) stressing the importance of documentation and presenting a method for writing reference manuals. The lineup of the models and utility programs of the project is as follows: Gtool5, ISPACK/SPML, SPMODEL, Deepconv, Dcpam, and Rdoc-f95. In the followings, features of each component are briefly described. Gtool5 (Ishiwatari et al., 2012) is a Fortran90 library, which provides data input/output interfaces and various utilities commonly used in the models of dcmodel project. A self-descriptive data format netCDF is adopted as a IO format of Gtool5. The interfaces of gtool5 library can reduce the number of operation steps for the data IO in the program code of the models compared with the interfaces of the raw netCDF library. Further, by use of gtool5 library, procedures for data IO and addition of metadata for post-processing can be easily implemented in the program codes in a consolidated form independent of the size and complexity of the models. ``ISPACK'' is the spectral transformation library and ``SPML (SPMODEL library)'' (Takehiro et al., 2006) is its wrapper library. Most prominent feature of SPML is a series of array-handling functions with systematic function naming rules, and this enables us to write codes with a form which is easily deduced from the mathematical expressions of the governing equations. ``SPMODEL'' (Takehiro et al., 2006) is a collection of various sample programs using ``SPML''. These sample programs provide the basekit for simple numerical experiments of geophysical fluid dynamics. For example, SPMODEL includes 1-dimensional KdV equation model, 2-dimensional barotropic, shallow water, Boussinesq models, 3-dimensional MHD dynamo models in rotating spherical shells. These models are written in the common style in harmony with SPML functions. ``Deepconv'' (Sugiyama et al., 2010) and ``Dcpam'' are a cloud resolving model and a general circulation model for the purpose of applications to the planetary atmospheres, respectively. ``Deepconv'' includes several physical processes appropriate for simulations of Jupiter and Mars atmospheres, while ``Dcpam'' does for simulations of Earth, Mars, and Venus-like atmospheres. ``Rdoc-f95'' is a automatic generator of reference manuals of Fortran90/95 programs, which is an extension of ruby documentation tool kit ``rdoc''. It analyzes dependency of modules, functions, and subroutines in the multiple program source codes. At the same time, it can list up the namelist variables in the programs.
Does an Intrinsic Magnetic Field Inhibit or Enhance Planetary Ionosphere Outflow and Loss?

NASA Astrophysics Data System (ADS)

Strangeway, R. J.; Russell, C. T.; Luhmann, J. G.; Moore, T. E.; Foster, J. C.; Barabash, S. V.; Nilsson, H.

2017-12-01

A characteristic feature of the planets Earth, Venus and Mars is the observation of the outflow of ionospheric ions, most notably oxygen. The oxygen ion outflow is frequently assumed to be a proxy for the loss of water from the planetary atmosphere. In terms of global outflow rates for the Earth the rate varies from 1025 to 1026 s-1, depending on geomagnetic activity. For both Venus and Mars global rates of the order 5x1024 s-1 have been reported. Venus and Mars do not have a large-scale intrinsic magnetic field, and there are several pathways for atmospheric and ionospheric loss. At Mars, because of its low gravity, neutral oxygen can escape through dissociative recombination. At Venus only processes related to the solar wind interaction with the planet such as sputtering and direct scavenging of the ionosphere by the solar wind can result in oxygen escape. At the Earth the intrinsic magnetic field forms a barrier to the solar wind, but reconnection of the Earth's magnetic field with the Interplanetary Magnetic Field allows solar wind energy and momentum to be transferred into the magnetosphere, resulting in ionospheric outflows. Observations of oxygen ions at the dayside magnetopause suggest that at least some of these ions escape. In terms of the evolution of planetary atmospheres how the solar-wind driven escape rates vary for magnetized versus umagnetized planets is also not clear. An enhanced solar wind dynamic pressure will increase escape from the unmagnetized planets, but it may also result in enhanced reconnection at the Earth, increasing outflow and loss rates for the Earth as well. Continued improvement in our understanding of the different pathways for ionospheric and atmospheric loss will allow us to determine how effective an intrinsic planetary field is in preserving a planetary atmosphere, or if we have to look for other explanations as to why the atmospheres of Venus and Mars have evolved to their desiccated state.
Energy Dissipation in the Upper Atmospheres of TRAPPIST-1 Planets

NASA Astrophysics Data System (ADS)

Cohen, Ofer; Glocer, Alex; Garraffo, Cecilia; Drake, Jeremy J.; Bell, Jared M.

2018-03-01

We present a method to quantify the upper limit of the energy transmitted from the intense stellar wind to the upper atmospheres of three of the TRAPPIST-1 planets (e, f, and g). We use a formalism that treats the system as two electromagnetic regions, where the efficiency of the energy transmission between one region (the stellar wind at the planetary orbits) to the other (the planetary ionospheres) depends on the relation between the conductances and impedances of the two regions. Since the energy flux of the stellar wind is very high at these planetary orbits, we find that for the case of high transmission efficiency (when the conductances and impedances are close in magnitude), the energy dissipation in the upper planetary atmospheres is also very large. On average, the Ohmic energy can reach 0.5–1 W m‑2, about 1% of the stellar irradiance and 5–15 times the EUV irradiance. Here, using constant values for the ionospheric conductance, we demonstrate that the stellar wind energy could potentially drive large atmospheric heating in terrestrial planets, as well as in hot Jupiters. More detailed calculations are needed to assess the ionospheric conductance and to determine more accurately the amount of heating the stellar wind can drive in close-orbit planets.
Detecting tree-like multicellular life on extrasolar planets.

PubMed

Doughty, Christopher E; Wolf, Adam

2010-11-01

Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems.
A dynamical perspective on the energetic particles precipitation-middle atmosphere interaction

NASA Astrophysics Data System (ADS)

Karami, Khalil; Sinnhuber, Miriam; Versick, Stefan; Braesicke, Peter

2015-04-01

Energetic particles including protons, electrons and heavier ions, enter the Earth's atmosphere over polar region of both hemispheres, where the geomagnetic lines are considered to be open and connected to the interplanetary medium. This condition allows direct access for energetic particles of solar or galactic origin to directly deposit their own energy into the middle and upper atmosphere. Such particle precipitations can greatly disturb the chemical composition of the upper and middle atmosphere. At polar latitudes, these particles have the potential to penetrate from thermosphere deep into the mesosphere and in rare occasions into the stratosphere. The most important are changes to the budget of atmospheric nitric oxides, NOy, and to atmospheric reactive hydrogen oxides, HOx, which both contribute to ozone loss in the stratosphere and mesosphere. The chemistry-climate general circulation model ECHAM5/MESSy is used to investigate the impact of changed ozone concentration due to energetic particles precipitation on temperatures and wind fields. The simulated anomalies of both zonal mean temperature and zonal wind suggest that these changes are very unlikely to be caused in situ by ozone depletion and indirect dynamical condition is important. The results of our simulations suggests that ozone perturbation is a starting point for a chain of processes resulting in temperature and circulation changes in many areas of the atmosphere. Different dynamical analysis (e.g., frequency of sudden stratospheric warming, dates of stratospheric final warming, divergence of Eliassen-Palm flux and refractive index of planetary waves) are performed to investigate the impact of ozone anomaly originated from high energetic particle precipitation on middle atmospheric temperature and circulation.
A high-resolution model of the planetary boundary layer - Sensitivity tests and comparisons with SESAME-79 data

NASA Technical Reports Server (NTRS)

Zhang, D.; Anthes, R. A.

1982-01-01

A one-dimensional, planetary boundary layer (PBL) model is presented and verified using April 10, 1979 SESAME data. The model contains two modules to account for two different regimes of turbulent mixing. Separate parameterizations are made for stable and unstable conditions, with a predictive slab model for surface temperature. Atmospheric variables in the surface layer are calculated with a prognostic model, with moisture included in the coupled surface/PBL modeling. Sensitivity tests are performed for factors such as moisture availability, albedo, surface roughness, and thermal capacity, and a 24 hr simulation is summarized for day and night conditions. The comparison with the SESAME data comprises three hour intervals, using a time-dependent geostrophic wind. Close correlations were found with daytime conditions, but not in nighttime thermal structure, while the turbulence was faithfully predicted. Both geostrophic flow and surface characteristics were shown to have significant effects on the model predictions
Three dimensional simulation of spatial and temporal variability of stratospheric hydrogen chloride

NASA Technical Reports Server (NTRS)

Kaye, Jack A.; Rood, Richard B.; Jackman, Charles H.; Allen, Dale J.; Larson, Edmund M.

1989-01-01

Spatial and temporal variability of atmospheric HCl columns are calculated for January 1979 using a three-dimensional chemistry-transport model designed to provide the best possible representation of stratospheric transport. Large spatial and temporal variability of the HCl columns is shown to be correlated with lower stratospheric potential vorticity and thus to be of dynamical origin. Systematic longitudinal structure is correlated with planetary wave structure. These results can help place spatially and temporally isolated column and profile measurements in a regional and/or global perspective.
The solar system: Importance of research to the biological sciences

NASA Technical Reports Server (NTRS)

Klein, Harold P.

1992-01-01

An attempt is made to describe the scope of scientific areas that comprise the current field of exobiology in the United States. From investigations of astrophysical phenomena that deal with the birth of stars and planetary systems to questions of molecular biology involving phylogenetic relationships among organisms, from attempts to simulate the synthesis of biological precursor molecules in the chemistry laboratory to making measurements of the organic constituents of Titan's atmosphere, these researches all converge toward a common objective--answering the question of how life came about in the universe.
Evaluating Mesoscale Simulations of the Coastal Flow Using Lidar Measurements

NASA Astrophysics Data System (ADS)

Floors, R.; Hahmann, A. N.; Peña, A.

2018-03-01

The atmospheric flow in the coastal zone is investigated using lidar and mast measurements and model simulations. Novel dual-Doppler scanning lidars were used to investigate the flow over a 7 km transect across the coast, and vertically profiling lidars were used to study the vertical wind profile at offshore and onshore positions. The Weather, Research and Forecasting model is set up in 12 different configurations using 2 planetary boundary layer schemes, 3 horizontal grid spacings and varied sources of land use, and initial and lower boundary conditions. All model simulations describe the observed mean wind profile well at different onshore and offshore locations from the surface up to 500 m. The simulated mean horizontal wind speed gradient across the shoreline is close to that observed, although all simulations show wind speeds that are slightly higher than those observed. Inland at the lowest observed height, the model has the largest deviations compared to the observations. Taylor diagrams show that using ERA-Interim data as boundary conditions improves the model skill scores. Simulations with 0.5 and 1 km horizontal grid spacing show poorer model performance compared to those with a 2 km spacing, partially because smaller resolved wave lengths degrade standard error metrics. Modeled and observed velocity spectra were compared and showed that simulations with the finest horizontal grid spacing resolved more high-frequency atmospheric motion.
Simulated CO2 Snowfalls and Baroclinic Waves in the Northern Winter Polar Atmosphere on Mars: Feasibility of Forecasts

NASA Astrophysics Data System (ADS)

Kuroda, T.; Medvedev, A. S.; Kasaba, Y.; Hartogh, P.

2013-12-01

The seasonal CO2 polar cap is formed from ice particles that have fallen from the atmosphere as well as those condensed directly on the surface. The possible occurrence of CO2 snowfall in the winter polar regions have been observed, and previous simulation studies have indicated that the longitudinal irregularities of CO2 ice clouds in the northern polar region seemed to be linked to local weather phenomena. Transient planetary waves are the prominent dynamical feature during northern winters in the martian atmosphere, and this study focuses on revealing the mechanism of how the dynamical influence of transient planetary waves affects the occurrences of CO2 ice clouds, snowfalls and formations of seasonal CO2 polar cap in high latitudes during northern winters. The DRAMATIC (Dynamics, RAdiation, MAterial Transport and their mutual InteraCtions) MGCM, which is used for this study, is based on a Japanese terrestrial model (CCSR/NIES/FRCGC MIROC) with a spectral solver for the three-dimensional primitive equations. In this simulation the horizontal resolution is set at about 5.6° × 5.6° (~333 km at equator), the vertical grid consists of 69 σ-levels with the top of the model at about 100 km. Realistic topography, albedo, thermal inertia and roughness data for the Mars surface are included. Radiative effects of CO2 gas (considering only LTE) and dust, in solar and infrared wavelengths, are taken into account. We have implemented a simple scheme representing the formation and transport of CO2 ice clouds into our MGCM, and investigated snowfall in high latitudes during northern winters. The MGCM simulations showed that the CO2 ice clouds are formed at altitudes of up to ~40 km in the northern polar region (northward of 70° N) during winter, which is consistent with the observations (MRO-MCS and MGS-MOLA). In addition, we found that the occurrence of the CO2 ice clouds correlated to a large degree with the cold phases of transient planetary waves. In the altitudes above ~15 km, the cloud formations are very much aligned with the baroclinic waves with zonal wavenumber of 1 and 5-6 sols period. In the lower altitudes the baroclinic waves components with shorter periods (~3 sols) also affect the cloud formations. The fate of ice particles during sedimentation depends on the thermal structure below because it takes ~0.2 sols for particles to descend from 25 km to the surface, which is much shorter than the periods of the transient waves. We found that ice particles formed up to ~20 km can reach the surface in the form of snowfall in certain longitude regions (in 30° W-60° E), while in others these particles likely sublimate in the lower warmer atmospheric layers. Given the regular nature of such atmospheric waves on Mars, the results of this study suggest that the snowstorms may be predicted several weeks in advance. It is simply impossible to predict the snowfall somewhere on Earth in such a long time ahead, but this may be different on Mars. For missions to Mars aiming to explore these regions with rovers, such weather forecasts would offer the possibility of choosing a route that avoids heavy snow storms.
Seeing the Invisible: Educating the Public on Planetary Magnetic Fields and How they Affect Atmospheres

NASA Astrophysics Data System (ADS)

Fillingim, M. O.; Brain, D. A.; Peticolas, L. M.; Schultz, G.; Yan, D.; Guevara, S.; Randol, S.

2009-12-01

Magnetic fields and charged particles are difficult for school children, the general public, and scientists alike to visualize. But studies of planetary magnetospheres and ionospheres have broad implications for planetary evolution, from the deep interior to the ancient climate, that are important to communicate to each of these audiences. This presentation will highlight the visualization materials that we are developing to educate audiences on the magnetic fields of planets and how they affect atmospheres. The visualization materials that we are developing consist of simplified data sets that can be displayed on spherical projection systems and portable 3-D rigid models of planetary magnetic fields.We are developing presentations for science museums and classrooms that relate fundamental information about the Martian magnetic field, how it differs from Earth’s, and why the differences are significant.
Atmospheric Modeling of Mars Methane Plumes

NASA Astrophysics Data System (ADS)

Mischna, Michael A.; Allen, M.; Lee, S.

2010-10-01

We present two complementary methods for isolating and modeling surface source releases of methane in the martian atmosphere. From recent observations, there is strong evidence that periodic releases of methane occur from discrete surface locations, although the exact location and mechanism of release is still unknown. Numerical model simulations with the Mars Weather Research and Forecasting (MarsWRF) general circulation model (GCM) have been applied to the ground-based observations of atmospheric methane by Mumma et al., (2009). MarsWRF simulations reproduce the natural behavior of trace gas plumes in the martian atmosphere, and reveal the development of the plume over time. These results provide constraints on the timing and location of release of the methane plume. Additional detections of methane have been accumulated by the Planetary Fourier Spectrometer (PFS) on board Mars Express. For orbital observations, which generally have higher frequency and resolution, an alternate approach to source isolation has been developed. Drawing from the concept of natural selection within biology, we apply an evolutionary computational model to this problem of isolating source locations. Using genetic algorithms that `reward’ best-fit matches between observations and GCM plume simulations (also from MarsWRF) over many generations, we find that we can potentially isolate source locations to within tens of km, which is within the roving capabilities of future Mars rovers. Together, these methods present viable numerical approaches to restricting the timing, duration and size of methane release events, and can be used for other trace gas plumes on Mars as well as elsewhere in the solar system.
Stellar occultation studies of the solar system

NASA Technical Reports Server (NTRS)

Elliot, J. L.

1979-01-01

The paper covers the principles, observational procedures, and results relating to occultations of stars by solar system bodies other than the moon. Physical processes involved in occultations are presented including (1) extinction by ring material, (2) differential refraction by a planetary atmosphere, (3) extinction by a planetary atmosphere, and (4) Fresnel diffraction by sharp edges. It is noted that from a sufficient number of immersion and emersion timings of a stellar occultation, the radius and ellipticity of the occulting body can be accurately determined. From an occultation by a planet having an atmosphere, temperature, pressure, and number density profiles can be obtained along with information about the composition of the atmosphere and the extinction.
Understanding the formation and composition of hazes in planetary atmospheres that contain carbon monoxide

NASA Astrophysics Data System (ADS)

Hörst, S. M.; Yoon, Y. H.; Hicks, R. K.; Tolbert, M. A.

2012-09-01

Measurements from the Cassini Plasma Spectrometer (CAPS) have revealed the presence of molecules in Titan's ionosphere with masses in excess of hundreds of amu. Negative ions with mass/charge (m/z) up to 10,000 amu/q [1] and positive ions with m/z up to 400 amu/q [2] have been detected. CAPS has also observed O+ flowing into Titan's upper atmosphere [3], which appears to originate from Enceladus and is likely the source of oxygen bearing molecules in Titan's atmosphere [4]. The observed O+ is deposited in the region now known to contain large organic molecules. A recent Titan atmosphere simulation experiment has shown that incorporation of oxygen into Titan aerosol analogues results in the formation of all five nucleotide bases and the two smallest amino acids, glycine and alanine [5]. Similar chemical processes may have occurred in the atmosphere of the early Earth, or in the atmospheres of extrasolar planets; atmospheric aerosols may be an important source of the building blocks of life. Atmospheric aerosols play an important role in determining the radiation budget of an atmosphere and can also provide a wealth of organic material to the surface. The presence of atmospheric aerosols has been invoked to explain the relatively featureless spectrum of HD 189773b, including the lack of predicted atmospheric Na and K spectral lines [9]. The majority of the O+ precipitating into Titan's atmosphere forms CO (O(3P)+CH3 -> CO+H2+H) [4]. CO has also been detected in the atmospheres of a number of exoplanets including HD 189733b, HD 209458b, and WASP-12b [6-8]. It is therefore important to understand the role CO plays in the formation and composition of hazes in planetary atmospheres. Using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) (see e.g. [10]) we have obtained in situ composition measurements of aerosol particles (so-called "tholins") produced in N2/CH4/CO gas mixtures subjected to either FUV radiation (deuterium lamp, 115-400 nm) or a spark discharge for a range of initial CO mixing ratios. A comparison of the composition of tholins produced using the two different energy sources will be presented. The effect of variation of CO mixing ratio on aerosol production and composition will also be discussed.
State of the Haze: The Causes and Consequences of a Hydrocarbon-rich Neoarchean Atmosphere

NASA Astrophysics Data System (ADS)

Zerkle, A.; Izon, G. J.; Claire, M.

2016-12-01

Atmospheric oxygen is thought to have rose irreversibly during the Great Oxidation Event (GOE) 2.4 billion-years-ago, though recent evidence shows that dynamic planetary transitions were also occurring prior to the oxidation of the atmosphere. We've recently documented perturbations in the reducing Neoarchean atmosphere, whereby the planet was periodically enshrouded in a CH4-rich haze. This scenario is based on coupled C- and S-isotope records from two continents, spanning a period of 200 million years [1-3]. A re-evaluation of these data at high resolution alongside additional proxies for trace element and nutrient analyses reveals that haze formed geologically rapidly, as a transient response to top-down stimulation of the biosphere. Net methane fluxes were ultimately controlled by the relative availability of organic-carbon and sulfate, with methanogenesis able to out-pace anaerobic methane oxidation in the low sulfate world of the Neoarchean. In addition, elevated CH4 flux to the atmosphere would have accelerated planetary hydrogen loss, expediting planetary oxidation and paving the way for the GOE [4]. These records suggest that the Neoarchean likely represented a unique state of the Earth System where links between the sulfur and methane cycles played a pivotal role in planetary oxidation and the contingent biological innovations that followed. [1] Zerkle et al. (2012) Nature Geoscience; [2] Farquhar et al. (2013) PNAS; [3] Izon et al. (2015) EPSL; [4] Izon et al. (in review).
The Dependence of the Ice-Albedo Feedback on Atmospheric Properties

PubMed Central

Selsis, F.; Kitzmann, D.; Rauer, H.

2013-01-01

Abstract Ice-albedo feedback is a potentially important destabilizing effect for the climate of terrestrial planets. It is based on the positive feedback between decreasing surface temperatures, an increase of snow and ice cover, and an associated increase in planetary albedo, which then further decreases surface temperature. A recent study shows that for M stars, the strength of the ice-albedo feedback is reduced due to the strong spectral dependence of stellar radiation and snow/ice albedos; that is, M stars primarily emit in the near IR, where the snow and ice albedo is low, and less in the visible, where the snow/ice albedo is high. This study investigates the influence of the atmosphere (in terms of surface pressure and atmospheric composition) on this feedback, since an atmosphere was neglected in previous studies. A plane-parallel radiative transfer model was used for the calculation of planetary albedos. We varied CO2 partial pressures as well as the H2O, CH4, and O3 content in the atmosphere for planets orbiting Sun-like and M type stars. Results suggest that, for planets around M stars, the ice-albedo effect is significantly reduced, compared to planets around Sun-like stars. Including the effects of an atmosphere further suppresses the sensitivity to the ice-albedo effect. Atmospheric key properties such as surface pressure, but also the abundance of radiative trace gases, can considerably change the strength of the ice-albedo feedback. For dense CO2 atmospheres of the order of a few to tens of bar, atmospheric rather than surface properties begin to dominate the planetary radiation budget. At high CO2 pressures, the ice-albedo feedback is strongly reduced for planets around M stars. The presence of trace amounts of H2O and CH4 in the atmosphere also weakens the ice-albedo effect for both stellar types considered. For planets around Sun-like stars, O3 could also lead to a very strong decrease of the ice-albedo feedback at high CO2 pressures. Key Words: Atmospheric compositions—Extrasolar terrestrial planets—Snowball Earth—Planetary atmospheres—Radiative transfer. Astrobiology 13, 899–909. PMID:24111995
S.A.M., the Italian Martian Simulation Chamber

NASA Astrophysics Data System (ADS)

Galletta, G.; Ferri, F.; Fanti, G.; D'Alessandro, M.; Bertoloni, G.; Pavarin, D.; Bettanini, C.; Cozza, P.; Pretto, P.; Bianchini, G.; Debei, S.

2006-12-01

The Martian Environment Simulator (SAM “Simulatore di Ambiente Marziano”) is a interdisciplinary project of Astrobiology done at University of Padua. The research is aimed to the study of the survival of the microorganisms exposed to the “extreme” planetary environment. The facility has been designed in order to simulate Mars’ environmental conditions in terms of atmospheric pressure, temperature cycles and UV radiation dose. The bacterial cells, contained into dedicated capsules, will be exposed to thermal cycles simulating diurnal and seasonal Martian cycles. The metabolism of the different biological samples will be analysed at different phases of the experiment, to study their survival and eventual activity of protein synthesis (mortality, mutations and capability of DNA reparing). We describe the experimental facility and provide the perspectives of the biological experiments we will perform in order to provide hints on the possibility of life on Mars either autochthonous or imported from Earth.

Rugged, no-moving-parts windspeed and static pressure probe designs for measurements in planetary atmospheres

NASA Technical Reports Server (NTRS)

Bedard, A. J., Jr.; Nishiyama, R. T.

1993-01-01

Instruments developed for making meteorological observations under adverse conditions on Earth can be applied to systems designed for other planetary atmospheres. Specifically, a wind sensor developed for making measurements within tornados is capable of detecting induced pressure differences proportional to wind speed. Adding strain gauges to the sensor would provide wind direction. The device can be constructed in a rugged form for measuring high wind speeds in the presence of blowing dust that would clog bearings and plug passages of conventional wind speed sensors. Sensing static pressure in the lower boundary layer required development of an omnidirectional, tilt-insensitive static pressure probe. The probe provides pressure inputs to a sensor with minimum error and is inherently weather-protected. The wind sensor and static pressure probes have been used in a variety of field programs and can be adapted for use in different planetary atmospheres.
An assessment of thermal, wind, and planetary wave changes in the middle and lower atmosphere due to 11-year UV flux variations

NASA Technical Reports Server (NTRS)

Callis, L. B.; Alpert, J. C.; Geller, M. A.

1985-01-01

Hines (1974) speculated that solar-induced modifications of the middle and upper atmosphere may alter the transmissivity of the stratosphere to upwardly propagating atmospheric waves. It was suggested that subsequent constructive or destructive interference may result in a change of phase or amplitude of these waves in the troposphere leading to weather or climate changes. The present investigation has the objective to bring together both radiative transfer and planetary wave studies in an effort to assess specifically whether Hines mechanism can be initiated by the solar ultraviolet flux variability assumed to be associated with the 11-year solar cycle. The obtained results suggest that the presently studied mechanism, which links solar-induced zonal wind changes in the stratosphere and mesosphere to planetary wave changes in the troposphere, is not strong enough to cause substantive changes in the troposphere.
Middle Atmosphere Dynamics with Gravity Wave Interactions in the Numerical Spectral Model: Tides and Planetary Waves

NASA Technical Reports Server (NTRS)

Mayr, Hans G.; Mengel, J. G.; Chan, K. L.; Huang, F. T.

2010-01-01

As Lindzen (1981) had shown, small-scale gravity waves (GW) produce the observed reversals of the zonal-mean circulation and temperature variations in the upper mesosphere. The waves also play a major role in modulating and amplifying the diurnal tides (DT) (e.g., Waltersheid, 1981; Fritts and Vincent, 1987; Fritts, 1995a). We summarize here the modeling studies with the mechanistic numerical spectral model (NSM) with Doppler spread parameterization for GW (Hines, 1997a, b), which describes in the middle atmosphere: (a) migrating and non-migrating DT, (b) planetary waves (PW), and (c) global-scale inertio gravity waves. Numerical experiments are discussed that illuminate the influence of GW filtering and nonlinear interactions between DT, PW, and zonal mean variations. Keywords: Theoretical modeling, Middle atmosphere dynamics, Gravity wave interactions, Migrating and non-migrating tides, Planetary waves, Global-scale inertio gravity waves.
DETECTING PLANETARY GEOCHEMICAL CYCLES ON EXOPLANETS: ATMOSPHERIC SIGNATURES AND THE CASE OF SO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaltenegger, L.; Sasselov, D., E-mail: lkaltene@cfa.harvard.ed

2010-01-10

We study the spectrum of a planetary atmosphere to derive detectable features in low resolution of different global geochemical cycles on exoplanets-using the sulfur cycle as our example. We derive low-resolution detectable features for first generation space- and ground-based telescopes as a first step in comparative planetology. We assume that the surfaces and atmospheres of terrestrial exoplanets (Earth-like and super-Earths) will most often be dominated by a specific geochemical cycle. Here we concentrate on the sulfur cycle driven by outgassing of SO{sub 2} and H{sub 2}S followed by their transformation to other sulfur-bearing species, which is clearly distinguishable from themore » carbon cycle, which is driven by outgassing of CO{sub 2}. Due to increased volcanism, the sulfur cycle is potentially the dominant global geochemical cycle on dry super-Earths with active tectonics. We calculate planetary emission, reflection, and transmission spectrum from 0.4 mum to 40 mum with high and low resolution to assess detectable features using current and Archean Earth models with varying SO{sub 2} and H{sub 2}S concentrations to explore reducing and oxidizing habitable environments on rocky planets. We find specific spectral signatures that are observable with low resolution in a planetary atmosphere with high SO{sub 2} and H{sub 2}S concentration. Therefore, first generation space- and ground-based telescopes can test our understanding of geochemical cycles on rocky planets and potentially distinguish planetary environments dominated by the carbon and sulfur cycles.« less
Lunar tidal effects during the 2013 stratospheric sudden warming as simulated by the TIME-GCM

NASA Astrophysics Data System (ADS)

Maute, A. I.; Forbes, J. M.; Zhang, X.; Fejer, B. G.; Yudin, V. A.; Pedatella, N. M.

2015-12-01

Stratospheric Sudden Warmings (SSW) are associated with strong planetary wave activity in the winterpolar stratosphere which result in a very disturbed middle atmosphere. The changes in the middle atmospherealter the propagation conditions and the nonlinear interactions of waves and tides, and result in SSW signals in the upper atmosphere in e.g., neutral winds, electric fields, ionospheric currents and plasma distribution. The upper atmosphere changes can be significant at low-latitudes even during medium solar flux conditions. Observationsalso reveal a strong lunar signal during SSW periods in the low latitude vertical drifts and in ionospheric quantities. Forbes and Zhang [2012] demonstrated that during the 2009 SSW period the Pekeris resonance peak of the atmosphere was altered such that the M2 and N2 lunar tidal componentsgot amplified. This study focuses on the effect of the lunar tidal forcing on the thermosphere-ionosphere system during theJanuary 2013 SSW period. We employthe NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM)with a nudging scheme using the Whole-Atmosphere-Community-Climate-Model-Extended (WACCM-X)/Goddard Earth Observing System Model, Version 5 (GEOS5) results to simulate the effects of meteorological forcing on the upper atmosphere. Additionally lunar tidal forcingis included at the lower boundary of the model. To delineate the lunar tidal effects a base simulation without lunar forcingis employed. Interestingly, Jicamarca observations of that period reveal a suppression of the daytime vertical drift before and after the drift enhancement due the SSW. The simulation suggests that the modulation of the vertical driftmay be caused by the interplay of the migrating solar and lunar semidiurnal tide, and therefore can only be reproduced by the inclusion of both lunar and solar tidal forcings in the model. In this presentation the changes due to the lunar tidal forcing will be quantified, and compared to observations.
Evaluation of NASA GISS post-CMIP5 single column model simulated clouds and precipitation using ARM Southern Great Plains observations

NASA Astrophysics Data System (ADS)

Zhang, Lei; Dong, Xiquan; Kennedy, Aaron; Xi, Baike; Li, Zhanqing

2017-03-01

The planetary boundary layer turbulence and moist convection parameterizations have been modified recently in the NASA Goddard Institute for Space Studies (GISS) Model E2 atmospheric general circulation model (GCM; post-CMIP5, hereafter P5). In this study, single column model (SCM P5) simulated cloud fractions (CFs), cloud liquid water paths (LWPs) and precipitation were compared with Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) groundbased observations made during the period 2002-08. CMIP5 SCM simulations and GCM outputs over the ARM SGP region were also used in the comparison to identify whether the causes of cloud and precipitation biases resulted from either the physical parameterization or the dynamic scheme. The comparison showed that the CMIP5 SCM has difficulties in simulating the vertical structure and seasonal variation of low-level clouds. The new scheme implemented in the turbulence parameterization led to significantly improved cloud simulations in P5. It was found that the SCM is sensitive to the relaxation time scale. When the relaxation time increased from 3 to 24 h, SCM P5-simulated CFs and LWPs showed a moderate increase (10%-20%) but precipitation increased significantly (56%), which agreed better with observations despite the less accurate atmospheric state. Annual averages among the GCM and SCM simulations were almost the same, but their respective seasonal variations were out of phase. This suggests that the same physical cloud parameterization can generate similar statistical results over a long time period, but different dynamics drive the differences in seasonal variations. This study can potentially provide guidance for the further development of the GISS model.
Understanding the Early Evolution of M dwarf Extreme Ultraviolet Radiation

NASA Astrophysics Data System (ADS)

Peacock, Sarah; Barman, Travis; Shkolnik, Evgenya

2015-11-01

The chemistry and evolution of planetary atmospheres depends on the evolution of high-energy radiation emitted by its host star. High levels of extreme ultraviolet (EUV) radiation can drastically alter the atmospheres of terrestrial planets through ionizing, heating, expanding, chemically modifying and eroding them during the first few billion years of a planetary lifetime. While there is evidence that stars emit their highest levels of far and near ultraviolet (FUV; NUV) radiation in the earliest stages of their evolution, we are currently unable to directly measure the EUV radiation. Most previous stellar atmosphere models under-predict FUV and EUV emission from M dwarfs; here we present new models for M stars that include prescriptions for the hot, lowest density atmospheric layers (chromosphere, transition region and corona), from which this radiation is emitted. By comparing our model spectra to GALEX near and far ultraviolet fluxes, we are able to predict the evolution of EUV radiation for M dwarfs from 10 Myr to a few Gyr. This research is the next major step in the HAZMAT (HAbitable Zones and M dwarf Activity across Time) project to analyze how the habitable zone evolves with the evolving properties of stellar and planetary atmospheres.
3D MODELING OF GJ1214b's ATMOSPHERE: FORMATION OF INHOMOGENEOUS HIGH CLOUDS AND OBSERVATIONAL IMPLICATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charnay, B.; Meadows, V.; Misra, A.

2015-11-01

The warm sub-Neptune GJ1214b has a featureless transit spectrum that may be due to the presence of high and thick clouds or haze. Here, we simulate the atmosphere of GJ1214b with a 3D General Circulation Model for cloudy hydrogen-dominated atmospheres, including cloud radiative effects. We show that the atmospheric circulation is strong enough to transport micrometric cloud particles to the upper atmosphere and generally leads to a minimum of cloud at the equator. By scattering stellar light, clouds increase the planetary albedo to 0.4–0.6 and cool the atmosphere below 1 mbar. However, the heating by ZnS clouds leads to themore » formation of a stratospheric thermal inversion above 10 mbar, with temperatures potentially high enough on the dayside to evaporate KCl clouds. We show that flat transit spectra consistent with Hubble Space Telescope observations are possible if cloud particle radii are around 0.5 μm, and that such clouds should be optically thin at wavelengths >3 μm. Using simulated cloudy atmospheres that fit the observed spectra we generate transit, emission, and reflection spectra and phase curves for GJ1214b. We show that a stratospheric thermal inversion would be readily accessible in near- and mid-infrared atmospheric spectral windows. We find that the amplitude of the thermal phase curves is strongly dependent on metallicity, but only slightly impacted by clouds. Our results suggest that primary and secondary eclipses and phase curves observed by the James Webb Space Telescope in the near- to mid-infrared should provide strong constraints on the nature of GJ1214b's atmosphere and clouds.« less
Profile inversion in presence of ray bending

NASA Technical Reports Server (NTRS)

Wallio, H. A.; Grossi, M. D.

1972-01-01

Inversion of radio occultation data for planetary atmospheres and ionospheres has been performed using the seismological Herglotz-Wiechert method, as adapted by Phinney and Anderson to the radio-occultation case. Profile reconstruction performed in computer simulated experiments with this approach have been compared with the ones obtained with the straight-ray Abel transform. For a thin atmosphere and ionosphere, like the ones encountered on Mars, microwave occultation data can be inverted accurately with both methods. For a dense ionosphere like the sun's corona, ray bending of microwaves is severe, and recovered refractivity by the Herglotz-Wiechert method provides significant improvement over the straight-ray Abel transform: the error reduces from more than 60% to less than 20% at a height of 60,000 km above the base of the corona.
Effects of orography on planetary scale flow

NASA Technical Reports Server (NTRS)

Smith, R. B.

1986-01-01

The earth's orography is composed of a wide variety of scales, each contributing to the spectrum of atmospheric motions. A well studied subject (originating with Charney and Eliassen) is the direct forcing of planetary scale waves by the planetary scale orography: primarily the Tibetan plateau and the Rockies. However, because of the non-linear terms in the equations of dynamic meteorology, even the smallest scales of mountain induced flow can contribute to the planetary scale if the amplitude of the small scale disturbance is sufficintly large. Two possible mechanisms for this are illustrated. First, preferentially located lee cyclones can force planetary waves by their meridional transport of heat and momentum (Hansen and Chen). Recent theories are helping to explain the phenomena of lee cyclogenesis (e.g., Smith, 1984, J.A.S.). Second, mesoscale mountain wave and severe downslope wind phenomena produce such a large local drag, that planetary scale waves can be produced. The mechanism of upscale transfer is easy to understand in this case as the standing planetary scale wave has a wavelength which depends on the mean structure of the atmosphere, and not on the width of the mountain (just as in small scale lee wave theory). An example of a theoretical description of a severe wind flow with very large drag is shown.
Composition of early planetary atmospheres - II. Coupled Dust and chemical evolution in protoplanetary discs

NASA Astrophysics Data System (ADS)

Cridland, A. J.; Pudritz, Ralph E.; Birnstiel, Tilman; Cleeves, L. Ilsedore; Bergin, Edwin A.

2017-08-01

We present the next step in a series of papers devoted to connecting the composition of the atmospheres of forming planets with the chemistry of their natal evolving protoplanetary discs. The model presented here computes the coupled chemical and dust evolution of the disc and the formation of three planets per disc model. Our three canonical planet traps produce a Jupiter near 1 AU, a Hot Jupiter and a Super-Earth. We study the dependence of the final orbital radius, mass, and atmospheric chemistry of planets forming in disc models with initial disc masses that vary by 0.02 M⊙ above and below our fiducial model (M_{disc,0} = 0.1 M_{⊙}). We compute C/O and C/N for the atmospheres formed in our three models and find that C/Oplanet ˜ C/O_{disc}, which does not vary strongly between different planets formed in our model. The nitrogen content of atmospheres can vary in planets that grow in different disc models. These differences are related to the formation history of the planet, the time and location that the planet accretes its atmosphere, and are encoded in the bulk abundance of NH3. These results suggest that future observations of atmospheric NH3 and an estimation of the planetary C/O and C/N can inform the formation history of particular planetary systems.
Mesoscale acid deposition modeling studies

NASA Technical Reports Server (NTRS)

Kaplan, Michael L.; Proctor, F. H.; Zack, John W.; Karyampudi, V. Mohan; Price, P. E.; Bousquet, M. D.; Coats, G. D.

1989-01-01

The work performed in support of the EPA/DOE MADS (Mesoscale Acid Deposition) Project included the development of meteorological data bases for the initialization of chemistry models, the testing and implementation of new planetary boundary layer parameterization schemes in the MASS model, the simulation of transport and precipitation for MADS case studies employing the MASS model, and the use of the TASS model in the simulation of cloud statistics and the complex transport of conservative tracers within simulated cumuloform clouds. The work performed in support of the NASA/FAA Wind Shear Program included the use of the TASS model in the simulation of the dynamical processes within convective cloud systems, the analyses of the sensitivity of microburst intensity and general characteristics as a function of the atmospheric environment within which they are formed, comparisons of TASS model microburst simulation results to observed data sets, and the generation of simulated wind shear data bases for use by the aviation meteorological community in the evaluation of flight hazards caused by microbursts.
A Department of Atmospheric and Planetary Sciences at Hampton University

NASA Astrophysics Data System (ADS)

Paterson, W. R.; McCormick, M. P.; Russell, J. M.; Anderson, J.; Kireev, S.; Loughman, R. P.; Smith, W. L.

2006-12-01

With this presentation we discuss the status of plans for a Department of Atmospheric and Planetary Sciences at Hampton University. Hampton University is a privately endowed, non-profit, non-sectarian, co-educational, and historically black university with 38 baccalaureate, 14 masters, and 4 doctoral degree programs. The graduate program in physics currently offers advanced degrees with concentration in Atmospheric Science. The 10 students now enrolled benefit substantially from the research experience and infrastructure resident in the university's Center for Atmospheric Sciences (CAS), which is celebrating its tenth anniversary. Promoting a greater diversity of participants in geosciences is an important objective for CAS. To accomplish this, we require reliable pipelines of students into the program. One such pipeline is our undergraduate minor in Space, Earth, and Atmospheric Sciences (SEAS minor). This minor concentraton of study is contributing to awareness of geosciences on the Hampton University campus, and beyond, as our students matriculate and join the workforce, or pursue higher degrees. However, the current graduate program, with its emphasis on physics, is not necessarily optimal for atmospheric scientists, and it limits our ability to recruit students who do not have a physics degree. To increase the base of candidate students, we have proposed creation of a Department of Atmospheric and Planetary Sciences, which could attract students from a broader range of academic disciplines. The revised curriculum would provide for greater concentration in atmospheric and planetary sciences, yet maintain a degree of flexibility to allow for coursework in physics or other areas to meet the needs of individual students. The department would offer the M.S. and Ph.D. degrees, and maintain the SEAS minor. The university's administration and faculty have approved our plan for this new department pending authorization by the university's board of trustees, which will consider the matter during their October, 2006 meeting.
Infrared line parameters at low temperatures relevant to planetary atmospheres

NASA Technical Reports Server (NTRS)

Varanasi, Prasad

1990-01-01

Employing the techniques that were described in several publications for measuring infrared lineshifts, linewidths and line intensities with a tunable diode laser, these parameters were measures for lines in the important infrared bands of several molecules of interest to the planetary astronomer at low temperatures that are relevant to planetary atmospheres using He, Ne, Ar, H2, N2, O2, and air as the perturbers. In addition to obtaining the many original data on the temperature dependence of the intensities and linewidths, it was also the first measurement of the same for the collision-induced lineshift of an infrared line and it showed that it was markedly different from that of the corresponding collision-broadened linewidth.
ATMOSPHERIC CIRCULATION OF BROWN DWARFS: JETS, VORTICES, AND TIME VARIABILITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xi; Showman, Adam P., E-mail: xiz@lpl.arizona.edu

2014-06-10

A variety of observational evidence demonstrates that brown dwarfs exhibit active atmospheric circulations. In this study we use a shallow-water model to investigate the global atmospheric dynamics in the stratified layer overlying the convective zone on these rapidly rotating objects. We show that the existence and properties of the atmospheric circulation crucially depend on key parameters including the energy injection rate and radiative timescale. Under conditions of strong internal heat flux and weak radiative dissipation, a banded flow pattern comprised of east-west jet streams spontaneously emerges from the interaction of atmospheric turbulence with the planetary rotation. In contrast, when themore » internal heat flux is weak and/or radiative dissipation is strong, turbulence injected into the atmosphere damps before it can self-organize into jets, leading to a flow dominated by transient eddies and isotropic turbulence instead. The simulation results are not very sensitive to the form of the forcing. Based on the location of the transition between jet-dominated and eddy-dominated regimes, we suggest that many brown dwarfs may exhibit atmospheric circulations dominated by eddies and turbulence (rather than jets) due to the strong radiative damping on these worlds, but a jet structure is also possible under some realistic conditions. Our simulated light curves capture important features from observed infrared light curves of brown dwarfs, including amplitude variations of a few percent and shapes that fluctuate between single-peak and multi-peak structures. More broadly, our work shows that the shallow-water system provides a useful tool to illuminate fundamental aspects of the dynamics on these worlds.« less
The Geology of the Terrestrial Planets

NASA Technical Reports Server (NTRS)

Carr, M. H. (Editor); Saunders, R. S.; Strom, R. G.; Wilhelms, D. E.

1984-01-01

The geologic history of the terrestrial planets is outlined in light of recent exploration and the revolution in geologic thinking. Among the topics considered are planet formation; planetary craters, basins, and general surface characteristics; tectonics; planetary atmospheres; and volcanism.
Identifying Planetary Biosignature Impostors: Spectral Features of CO and O4 Resulting from Abiotic O2/O3 Production

NASA Astrophysics Data System (ADS)

Schwieterman, Edward W.; Meadows, Victoria S.; Domagal-Goldman, Shawn D.; Deming, Drake; Arney, Giada N.; Luger, Rodrigo; Harman, Chester E.; Misra, Amit; Barnes, Rory

2016-03-01

O2 and O3 have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described. However, these abiotic planetary mechanisms modify the environment in potentially identifiable ways. Here we briefly discuss two of the most detectable spectral discriminants for abiotic O2/O3: CO and O4. We produce the first explicit self-consistent simulations of these spectral discriminants as they may be seen by James Webb Space Telescope (JWST). If JWST-NIRISS and/or NIRSpec observe CO (2.35, 4.6 μm) in conjunction with CO2 (1.6, 2.0, 4.3 μm) in the transmission spectrum of a terrestrial planet it could indicate robust CO2 photolysis and suggest that a future detection of O2 or O3 might not be biogenic. Strong O4 bands seen in transmission at 1.06 and 1.27 μm could be diagnostic of a post-runaway O2-dominated atmosphere from massive H-escape. We find that for these false positive scenarios, CO at 2.35 μm, CO2 at 2.0 and 4.3 μm, and O4 at 1.27 μm are all stronger features in transmission than O2/O3 and could be detected with S/Ns ≳ 3 for an Earth-size planet orbiting a nearby M dwarf star with as few as 10 transits, assuming photon-limited noise. O4 bands could also be sought in UV/VIS/NIR reflected light (at 0.345, 0.36, 0.38, 0.445, 0.475, 0.53, 0.57, 0.63, 1.06, and 1.27 μm) by a next generation direct-imaging telescope such as LUVOIR/HDST or HabEx and would indicate an oxygen atmosphere too massive to be biologically produced.
Maturation of the Asteroid Threat Assessment Project

NASA Technical Reports Server (NTRS)

Arnold, J. O..; Burkhard, C. D.

2017-01-01

As described at IPPW 12 [1], NASA initiated a new research activity focused on Planetary Defense (PD) on October 1, 2014. The overarching function of the Asteroid Threat Assessment Project (ATAP) is to provide capabilities to assess impact damage of any Near-Earth Object (NEO) that could inflict on the Earth. The activity includes four interrelated efforts: Initial Conditions (at the atmospheric entry interface); Entry Modeling (energy deposition in the atmosphere); Hazards (on the surface including winds, over pressures, thermal exposures, craters, tsunami and earthquakes) and Risk (physics-based). This paper outlines progress by ATAP and highlights achievements that are complimentary to activities of interest to the International Planetary Probe community. The ATAPs work is sponsored by NASAs Planetary Defense Coordination Office (PDCO), a part of the agency's Science Mission Directorate [1] Arnold, J. O., et. al., Overview of a New NASA Activity Focused on Planetary Defense, IPPW 12 Cologne Germany, June 15-19. 2015.
Origin and evolution of planetary atmospheres

NASA Technical Reports Server (NTRS)

Lewis, John S.

1992-01-01

This report concerns several research tasks related to the origin and evolution of planetary atmospheres and the large-scale distribution of volatile elements in the Solar System. These tasks and their present status are as follows: (1) we have conducted an analysis of the volatility and condensation behavior of compounds of iron, aluminum, and phosphorus in the atmosphere of Venus in response to publish interpretations of the Soviet Venera probe XRF experiment data, to investigate the chemistry of volcanic gases, injection of volatiles by cometary and asteroidal impactors, and reactions in the troposphere; (2) we have completed and are now writing up our research on condensation-accretion modeling of the terrestrial planets; (3) we have laid the groundwork for a detailed study of the effects of water transport in the solar nebula on the bulk composition, oxidation state, and volatile content of preplanetary solids; (4) we have completed an extensive laboratory study of cryovolcanic materials in the outer solar system; (5) we have begun to study the impact erosion and shock alteration of the atmosphere of Mars resulting from cometary and asteroidal bombardment; and (6) we have developed a new Monte Carlo model of the cometary and asteroidal bombardment flux on the terrestrial planets, including all relevant chemical and physical processes associated with atmospheric entry and impact, to assess both the hazards posed by this bombardment to life on Earth and the degree of cross-correlation between the various phenomena (NO(x) production, explosive yield, crater production, iridium signature, etc.) that characterize this bombardment. The purpose of these investigations has been to contribute to the developing understanding of both the dynamics of long-term planetary atmosphere evolution and the short-term stability of planetary surface environments.
Using Laboratory Methods to Better Understand Refractory Cloud Formation in Exoplanet Atmospheres

NASA Astrophysics Data System (ADS)

Kohler, E.; Ferguson, F.

2017-12-01

The high number of extrasolar planets found in recent years has brought a new importance to planetary atmospheres. These recently discovered planets show a large diversity in their masses, temperatures, orbital periods, and other properties. With such a diverse mix of planetary parameters, it is safe to assume that the atmospheric properties are just as varied. Recent literature suggests silicates and metals as possible condensates in extrasolar planetary atmospheres as well as the atmospheres of brown dwarfs. While theoretical studies have laid the foundation of cloud formation analysis, their findings still need to be validated via experiments. A verification of the condensation and vaporization predictions of refractory materials needs to be found in order to assist global circulation models in being as accurate as possible. The stability of minerals identified in the literature as potential candidates, will be tested in a thermogravimetric balance. The minerals will be pumped under vacuum for twenty-four hours under room temperature and then heated to a predetermined high temperature, dependent on the expected vaporization temperature of that sample. If there is apparent mass loss, then the temperature will be lowered at preset durations and mass measurements will be taken in similar measured increments. The data will be processed by a computer program in order to calculate the mass loss as a function of temperature. The current cloud formation and global circulation models are very important to the field of planetary science but their accuracy is hindered by the lack of experimental data. The aim of this work is to investigate the mineral stability of potential condensates in an effort to explain the formation of refractory clouds in the atmospheres of extrasolar planets and brown dwarfs.

Activities in planetary geology for the physical and earth sciences

NASA Technical Reports Server (NTRS)

Dalli, R.; Greeley, R.

1982-01-01

A users guide for teaching activities in planetary geology, and for physical and earth sciences is presented. The following topics are discussed: cratering; aeolian processes; planetary atmospheres, in particular the Coriolis Effect and storm systems; photogeologic mapping of other planets, Moon provinces and stratigraphy, planets in stereo, land form mapping of Moon, Mercury and Mars, and geologic features of Mars.
The importance of planetary rotation period for ocean heat transport.

PubMed

Cullum, J; Stevens, D; Joshi, M

2014-08-01

The climate and, hence, potential habitability of a planet crucially depends on how its atmospheric and ocean circulation transports heat from warmer to cooler regions. However, previous studies of planetary climate have concentrated on modeling the dynamics of atmospheres, while dramatically simplifying the treatment of oceans, which neglects or misrepresents the effect of the ocean in the total heat transport. Even the majority of studies with a dynamic ocean have used a simple so-called aquaplanet that has no continental barriers, which is a configuration that dramatically changes the ocean dynamics. Here, the significance of the response of poleward ocean heat transport to planetary rotation period is shown with a simple meridional barrier--the simplest representation of any continental configuration. The poleward ocean heat transport increases significantly as the planetary rotation period is increased. The peak heat transport more than doubles when the rotation period is increased by a factor of ten. There are also significant changes to ocean temperature at depth, with implications for the carbon cycle. There is strong agreement between the model results and a scale analysis of the governing equations. This result highlights the importance of both planetary rotation period and the ocean circulation when considering planetary habitability.
Estimation of Eddy Dissipation Rates from Mesoscale Model Simulations

NASA Technical Reports Server (NTRS)

Ahmad, Nashat N.; Proctor, Fred H.

2012-01-01

The Eddy Dissipation Rate is an important metric for representing the intensity of atmospheric turbulence and is used as an input parameter for predicting the decay of aircraft wake vortices. In this study, the forecasts of eddy dissipation rates obtained from the current state-of-the-art mesoscale model are evaluated for terminal area applications. The Weather Research and Forecast mesoscale model is used to simulate the planetary boundary layer at high horizontal and vertical mesh resolutions. The Bougeault-Lacarrer and the Mellor-Yamada-Janji schemes implemented in the Weather Research and Forecast model are evaluated against data collected during the National Aeronautics and Space Administration s Memphis Wake Vortex Field Experiment. Comparisons with other observations are included as well.
Observing the ExoEarth: Simulating the Retrieval of Exoplanet Parameters Using DSCOVR

NASA Astrophysics Data System (ADS)

Kane, S.; Cowan, N. B.; Domagal-Goldman, S. D.; Herman, J. R.; Robinson, T.; Stine, A.

2017-12-01

The field of exoplanets has rapidly expanded from detection to include exoplanet characterization. This has been enabled by developments such as the detection of terrestrial-sized planets and the use of transit spectroscopy to study exoplanet atmospheres. Studies of rocky planets are leading towards the direct imaging of exoplanets and the development of techniques to extract their intrinsic properties. The importance of properties such as rotation, albedo, and obliquity are significant since they inform planet formation theories and are key input parameters for Global Circulation Models used to determine surface conditions, including habitability. Thus, a complete characterization of exoplanets for understanding habitable climates requires the ability to measure these key planetary parameters. The retrieval of planetary rotation rates, albedos, and obliquities from highly undersampled imaging data can be honed using satellites designed to study the Earth's atmosphere. In this talk I will describe how the Deep Space Climate Observatory (DSCOVR) provides a unique opportunity to test such retrieval methods using data for the sunlit hemisphere of the Earth. Our methods use the high-resolution DSCOVR-EPIC images to simulate the Earth as an exoplanet, by deconvolving the images to match a variety of expected exoplanet mission requirements, and by comparing EPIC data with the cavity radiometer data from DSCOVR-NISTAR that views the Earth as a single pixel. Through this methodology, we are creating a grid of retrieval states as a function of image resolution, observing cadence, passband, etc. Our modeling of the DSCOVR data will provide an effective baseline from which to develop tools that can be applied to a variety of exoplanet imaging data.
Atmospheric, climatic and environmental research

NASA Technical Reports Server (NTRS)

Broecker, Wallace S.; Gornitz, Vivien M.

1992-01-01

Work performed on the three tasks during the report period is summarized. The climate and atmospheric modeling studies included work on climate model development and applications, paleoclimate studies, climate change applications, and SAGE II. Climate applications of Earth and planetary observations included studies on cloud climatology and planetary studies. Studies on the chemistry of the Earth and the environment are briefly described. Publications based on the above research are listed; two of these papers are included in the appendices.
MAGNETIC SCALING LAWS FOR THE ATMOSPHERES OF HOT GIANT EXOPLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menou, Kristen

2012-02-01

We present scaling laws for advection, radiation, magnetic drag, and ohmic dissipation in the atmospheres of hot giant exoplanets. In the limit of weak thermal ionization, ohmic dissipation increases with the planetary equilibrium temperature (T{sub eq} {approx}> 1000 K) faster than the insolation power does, eventually reaching values {approx}> 1% of the insolation power, which may be sufficient to inflate the radii of hot Jupiters. At higher T{sub eq} values still magnetic drag rapidly brakes the atmospheric winds, which reduces the associated ohmic dissipation power. For example, for a planetary field strength B = 10 G, the fiducial scaling lawsmore » indicate that ohmic dissipation exceeds 1% of the insolation power over the equilibrium temperature range T{sub eq} {approx} 1300-2000 K, with a peak contribution at T{sub eq} {approx} 1600 K. Evidence for magnetically dragged winds at the planetary thermal photosphere could emerge in the form of reduced longitudinal offsets for the dayside infrared hotspot. This suggests the possibility of an anticorrelation between the amount of hotspot offset and the degree of radius inflation, linking the atmospheric and interior properties of hot giant exoplanets in an observationally testable way. While providing a useful framework to explore the magnetic scenario, the scaling laws also reveal strong parameter dependencies, in particular with respect to the unknown planetary magnetic field strength.« less
Planetary Atmospheres and the Search for Life.

ERIC Educational Resources Information Center

Owen, Tobias

1982-01-01

Different ways in which the atmospheres of different planets have originated and evolved are discussed. Includes tables on the atmospheric composition of: (1) Earth; (2) Mars; (3) Venus; (4)Titan (Saturn's Satellite); and (5) the outer planets. (SK)
Broadening of spectral lines of CO2, N2O , H2CO, HCN, and H2S by pressure of gases dominant in planetary atmospheres (H2, He and CO2)

NASA Astrophysics Data System (ADS)

Samuels, Shanelle; Gordon, Iouli; Tan, Yan

2018-01-01

HITRAN1,2 is a compilation of spectroscopic parameters that a variety of computer codes use to predict and simulate the transmission and emission of light in planetary atmospheres. The goal of this project is to add to the potential of the HITRAN database towards the exploration of the planetary atmospheres by including parameters describing broadening of spectral lines by H2, CO2, and He. These spectroscopic data are very important for the study of the hydrogen and helium-rich atmospheres of gas giants as well as rocky planets with volcanic activities, including Venus and Mars, since their atmospheres are dominated by CO2. First step in this direction was accomplished by Wilzewski et al.3 where this was done for SO2, NH3, HF, HCl, OCS and C2H2. The molecules investigated in this work were CO2, N2O, H2CO, HCN and H2S. Line-broadening coefficients, line shifts and temperature-dependence exponents for transitions of these molecules perturbed by H2, CO2 and He have been assembled from available peer-reviewed experimental and theoretical sources. The data was evaluated and the database was populated with these data and their extrapolations/interpolations using semi-empirical models that were developed to this end.Acknowledgements: Financial support from NASA PDART grant NNX16AG51G and the Smithsonian Astrophysical Observatory Latino Initiative Program from the Latino Initiatives Pool, administered by the Smithsonian Latino Center is gratefully acknowledged.References: 1. HITRAN online http://hitran.org/2. Gordon, I.E., Rothman, L.S., Hill, C., Kochanov, R.V., Tan, Y., et al., 2017. The HITRAN2016 Molecular Spectroscopic Database. J. Quant. Spectrosc. Radiat. Transf. doi:10.1016/j.jqsrt.2017.06.0383. Wilzewski, J.S., Gordon, I.E., Kochanov, R. V., Hill, C., Rothman, L.S., 2016. H2, He, and CO2 line-broadening coefficients, pressure shifts and temperature-dependence exponents for the HITRAN database. Part 1: SO2, NH3, HF, HCl, OCS and C2H2. J. Quant. Spectrosc. Radiat. Transf. 168, 193–206. doi:10.1016/j.jqsrt.2015.09.003
Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces

NASA Astrophysics Data System (ADS)

Plane, John M. C.; Flynn, George J.; Määttänen, Anni; Moores, John E.; Poppe, Andrew R.; Carrillo-Sanchez, Juan Diego; Listowski, Constantino

2018-02-01

Recent advances in interplanetary dust modelling provide much improved estimates of the fluxes of cosmic dust particles into planetary (and lunar) atmospheres throughout the solar system. Combining the dust particle size and velocity distributions with new chemical ablation models enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; and the effects of the surface deposition of micrometeorites and cosmic spherules. There is discussion of impacts on all the planets, as well as on Pluto, Triton and Titan.
Dynamics and Statistical Mechanics of Rotating and non-Rotating Vortical Flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Chjan

Three projects were analyzed with the overall aim of developing a computational/analytical model for estimating values of the energy, angular momentum, enstrophy and total variation of fluid height at phase transitions between disordered and self-organized flow states in planetary atmospheres. It is believed that these transitions in equilibrium statistical mechanics models play a role in the construction of large-scale, stable structures including super-rotation in the Venusian atmosphere and the formation of the Great Red Spot on Jupiter. Exact solutions of the spherical energy-enstrophy models for rotating planetary atmospheres by Kac's method of steepest descent predicted phase transitions to super-rotating solid-bodymore » flows at high energy to enstrophy ratio for all planetary spins and to sub-rotating modes if the planetary spin is large enough. These canonical statistical ensembles are well-defined for the long-range energy interactions that arise from 2D fluid flows on compact oriented manifolds such as the surface of the sphere and torus. This is because in Fourier space available through Hodge theory, the energy terms are exactly diagonalizable and hence has zero range, leading to well-defined heat baths.« less
A Planetary Protection Strategy for the Mars Aerial Regional-Scale Environmental Survey (ARES) Mission Concept

NASA Technical Reports Server (NTRS)

Kuhl, Christopher A.

2008-01-01

The Aerial Regional-scale Environmental Survey (ARES) is a Mars exploration mission concept designed to send an airplane to fly through the lower atmosphere of Mars, with the goal of taking scientific measurements of the atmosphere, surface, and subsurface phenomenon. ARES was first proposed to the Mars Scout program in December 2002 for a 2007 launch opportunity and was selected to proceed with a Phase A study, step-2 proposal which was submitted in May 2003. ARES was not selected for the Scout mission, but efforts continued on risk reduction of the atmospheric flight system in preparation for the next Mars Scout opportunity in 2006. The ARES concept was again proposed in July 2006 to the Mars Scout program but was not selected to proceed into Phase A. This document describes the Planetary Protection strategy that was developed in ARES Pre Phase-A activities to help identify, early in the design process, certain hardware, assemblies, and/or subsystems that will require unique design considerations based on constraints imposed by Planetary Protection requirements. Had ARES been selected as an exploration project, information in this document would make up the ARES Project Planetary Protection Plan.
Exoplanets: A New Era of Comparative Planetology

NASA Astrophysics Data System (ADS)

Meadows, Victoria

2014-11-01

We now know of over 1700 planets orbiting other stars, and several thousand additional planetary candidates. These discoveries have the potential to revolutionize our understanding of planet formation and evolution, while providing targets for the search for life beyond the Solar System. Exoplanets display a larger diversity of planetary types than those seen in our Solar System - including low-density, low-mass objects. They are also found in planetary system architectures very different from our own, even for stars similar to our Sun. Over 20 potentially habitable planets are now known, and half of the M dwarfs stars in our Galaxy may harbor a habitable planet. M dwarfs are plentiful, and they are therefore the most likely habitable planet hosts, but their planets will have radiative and gravitational interactions with their star and sibling planets that are unlike those in our Solar System. Observations to characterize the atmospheres and surfaces of exoplanets are extremely challenging, and transit transmission spectroscopy has been used to measure atmospheric composition for a handful of candidates. Frustratingly, many of the smaller exoplanets have flat, featureless spectra indicative of planet-wide haze or clouds. The James Webb Space Telescope and future ground-based telescopes will improve transit transmission characterization, and enable the first search for signs of life in terrestrial exoplanet atmospheres. Beyond JWST, planned next-generation space telescopes will directly image terrestrial exoplanets, allowing surface and atmospheric characterization that is more robust to haze. Until these observations become available, there is a lot that we can do as planetary scientists to inform required measurements and future data interpretation. Solar System planets can be used as validation targets for extrasolar planet observations and models. The rich heritage of planetary science models can also be used to explore the potential diversity of exoplanet environments and star-planet interactions. And planetary remote-sensing can inform new techniques to identify environmental characteristics and biosignatures in exoplanet spectra.
Earth as an Exoplanet: Lessons in Recognizing Planetary Habitability

NASA Astrophysics Data System (ADS)

Meadows, Victoria; Robinson, Tyler; Misra, Amit; Ennico, Kimberly; Sparks, William B.; Claire, Mark; Crisp, David; Schwieterman, Edward; Bussey, D. Ben J.; Breiner, Jonathan

2015-01-01

Earth will always be our best-studied example of a habitable world. While extrasolar planets are unlikely to look exactly like Earth, they may share key characteristics, such as oceans, clouds and surface inhomogeneity. Earth's globally-averaged characteristics can therefore help us to recognize planetary habitability in data-limited exoplanet observations. One of the most straightforward ways to detect habitability will be via detection of 'glint', specular reflectance from an ocean (Robinson et al., 2010). Other methods include undertaking a census of atmospheric greenhouse gases, or attempting to measure planetary surface temperature and pressure, to determine if liquid water would be feasible on the planetary surface. Here we present recent research on detecting planetary habitability, led by the NASA Astrobiology Institute's Virtual Planetary Laboratory Team. This work includes a collaboration with the NASA Lunar Science Institute on the detection of ocean glint and ozone absorption using Lunar Crater Observation and Sensing Satellite (LCROSS) Earth observations (Robinson et al., 2014). This data/model comparison provides the first observational test of a technique that could be used to determine exoplanet habitability from disk-integrated observations at visible and near-infrared wavelengths. We find that the VPL spectral Earth model is in excellent agreement with the LCROSS Earth data, and can be used to reliably predict Earth's appearance at a range of phases relevant to exoplanet observations. Determining atmospheric surface pressure and temperature directly for a potentially habitable planet will be challenging due to the lack of spatial-resolution, presence of clouds, and difficulty in spectrally detecting many bulk constituents of terrestrial atmospheres. Additionally, Rayleigh scattering can be masked by absorbing gases and absorption from the underlying surface. However, new techniques using molecular dimers of oxygen (Misra et al., 2014) and nitrogen (Schwieterman et al., 2014) may provide an alternative means to determine terrestrial atmospheric pressure for both transit transmission and direct imaging observations.
Experimental and theoretical studies on the gas/solid/gas transformation cycle in extraterrestrial environments

NASA Astrophysics Data System (ADS)

Cottin, Hervé; Gazeau, Marie-Claire; Chaquin, Patrick; Raulin, François; Bénilan, Yves

2001-12-01

The ubiquity of molecular material in the universe, from hydrogen to complex organic matter, is the result of intermixed physicochemical processes that have occurred throughout history. In particular, the gas/solid/gas phase transformation cycle plays a key role in chemical evolution of organic matter from the interstellar medium to planetary systems. This paper focuses on two examples that are representative of the diversity of environments where such transformations occur in the Solar System: (1) the photolytic evolution from gaseous to solid material in methane containing planetary atmospheres and (2) the degradation of high molecular weight compounds into gas phase molecules in comets. We are currently developing two programs which couple experimental and theoretical studies. The aim of this research is to provide data necessary to build models in order to better understand (1) the photochemical evolution of Titan's atmosphere, through a laboratory program to determine quantitative spectroscopic data on long carbon chain molecules (polyynes) obtained in the SCOOP program (French acronym for Spectroscopy of Organic Compounds Oriented for Planetology), and (2) the extended sources in comets, through a laboratory program of quantitative studies of photochemical and thermal degradation processes on relevant polymers (e.g., Polyoxymethylene) by the SEMAPhOrE Cometaire program (French acronym for Experimental Simulation and Modeling Applied to Organic Chemistry in Cometary Environment).
Arctic Sea Ice Export Through Fram Strait and Atmospheric Planetary Waves

NASA Technical Reports Server (NTRS)

Cavalieri, Donald J.; Koblinsky, Chester (Technical Monitor)

2001-01-01

A link is found between the variability of Arctic sea ice export through Ram Strait and the phase of the longest atmospheric planetary wave (zonal wave 1) in SLP for the period 1958-1997. Previous studies have identified a link between From Strait ice export and the North Atlantic Oscillation (NAO), but this link has been described as unstable because of a lack of consistency over time scales longer than the last two decades. Inconsistent and low correlations are also found between From Strait ice export and the Arctic Oscillation (AD) index. This paper shows that the phase of zonal wave 1 explains 60% - 70% of the simulated From Strait ice export variance over the Goodyear period 1958 - 1997. Unlike the NAB and AD links, these high variances are consistent for both the first and second halves of the Goodyear period. This consistency is attributed to the sensitivity of the wave I phase at high latitudes to the presence of secondary low pressure systems in the Barents Sea that serve to drive sea ice southward through From Strait. These results provide further evidence that the phase of zonal wave 1 in SLP at high latitudes drives regional as well as hemispheric low frequency Arctic Ocean and sea ice variability.
The Implications of 3D Thermal Structure on 1D Atmospheric Retrieval

NASA Astrophysics Data System (ADS)

Blecic, Jasmina; Dobbs-Dixon, Ian; Greene, Thomas

2017-10-01

Using the atmospheric structure from a 3D global radiation-hydrodynamic simulation of HD 189733b and the open-source Bayesian Atmospheric Radiative Transfer (BART) code, we investigate the difference between the secondary-eclipse temperature structure produced with a 3D simulation and the best-fit 1D retrieved model. Synthetic data are generated by integrating the 3D models over the Spitzer, the Hubble Space Telescope (HST), and the James Web Space Telescope (JWST) bandpasses, covering the wavelength range between 1 and 11 μm where most spectroscopically active species have pronounced features. Using the data from different observing instruments, we present detailed comparisons between the temperature-pressure profiles recovered by BART and those from the 3D simulations. We calculate several averages of the 3D thermal structure and explore which particular thermal profile matches the retrieved temperature structure. We implement two temperature parameterizations that are commonly used in retrieval to investigate different thermal profile shapes. To assess which part of the thermal structure is best constrained by the data, we generate contribution functions for our theoretical model and each of our retrieved models. Our conclusions are strongly affected by the spectral resolution of the instruments included, their wavelength coverage, and the number of data points combined. We also see some limitations in each of the temperature parametrizations, as they are not able to fully match the complex curvatures that are usually produced in hydrodynamic simulations. The results show that our 1D retrieval is recovering a temperature and pressure profile that most closely matches the arithmetic average of the 3D thermal structure. When we use a higher resolution, more data points, and a parametrized temperature profile that allows more flexibility in the middle part of the atmosphere, we find a better match between the retrieved temperature and pressure profile and the arithmetic average. The Spitzer and HST simulated observations sample deep parts of the planetary atmosphere and provide fewer constraints on the temperature and pressure profile, while the JWST observations sample the middle part of the atmosphere, providing a good match with the middle and most complex part of the arithmetic average of the 3D temperature structure.
Uranus atmospheric dynamics and circulation

NASA Technical Reports Server (NTRS)

Allison, Michael; Beebe, Reta F.; Conrath, Barney J.; Hinson, David P.; Ingersoll, Andrew P.

1991-01-01

The observations, models, and theories relevant to the atmospheric dynamics and meteorology of Uranus are discussed. The available models for the large-scale heat transport and atmospheric dynamics as well as diagnostic interpretations of the Voyager data are reviewed. Some pertinent ideas and questions regarding the global circulation balance are considered, partly in comparison with other planetary atmospheres. The available data indicate atmospheric rotation at midlatitudes nearly 200 m/s faster than that of the planetary magnetic field. Analysis of the dynamical deformation of the shape and size of isobaric surfaces measured by the Voyager radio-occultation experiment suggests a subrotating equator at comparable altitudes. Infrared temperature retrievals above the cloud deck indicate a smaller equator-to-pole contrast than expected for purely radiative-convective equilibrium, but show local variations implying a latitudinally correlated decrease with altitude in the cloud-tracked wind.
Space Dust Collisions as a Planetary Escape Mechanism

NASA Astrophysics Data System (ADS)

Berera, Arjun

2017-12-01

It is observed that hypervelocity space dust, which is continuously bombarding Earth, creates immense momentum flows in the atmosphere. Some of this fast space dust inevitably will interact with the atmospheric system, transferring energy and moving particles around, with various possible consequences. This paper examines, with supporting estimates, the possibility that by way of collisions the Earth-grazing component of space dust can facilitate planetary escape of atmospheric particles, whether they are atoms and molecules that form the atmosphere or larger-sized particles. An interesting outcome of this collision scenario is that a variety of particles that contain telltale signs of Earth's organic story, including microbial life and life-essential molecules, may be "afloat" in Earth's atmosphere. The present study assesses the capability of this space dust collision mechanism to propel some of these biological constituents into space.
Formation of amino acids and nucleotide bases in a Titan atmosphere simulation experiment.

PubMed

Hörst, S M; Yelle, R V; Buch, A; Carrasco, N; Cernogora, G; Dutuit, O; Quirico, E; Sciamma-O'Brien, E; Smith, M A; Somogyi, A; Szopa, C; Thissen, R; Vuitton, V

2012-09-01

The discovery of large (>100 u) molecules in Titan's upper atmosphere has heightened astrobiological interest in this unique satellite. In particular, complex organic aerosols produced in atmospheres containing C, N, O, and H, like that of Titan, could be a source of prebiotic molecules. In this work, aerosols produced in a Titan atmosphere simulation experiment with enhanced CO (N(2)/CH(4)/CO gas mixtures of 96.2%/2.0%/1.8% and 93.2%/5.0%/1.8%) were found to contain 18 molecules with molecular formulae that correspond to biological amino acids and nucleotide bases. Very high-resolution mass spectrometry of isotopically labeled samples confirmed that C(4)H(5)N(3)O, C(4)H(4)N(2)O(2), C(5)H(6)N(2)O(2), C(5)H(5)N(5), and C(6)H(9)N(3)O(2) are produced by chemistry in the simulation chamber. Gas chromatography-mass spectrometry (GC-MS) analyses of the non-isotopic samples confirmed the presence of cytosine (C(4)H(5)N(3)O), uracil (C(5)H(4)N(2)O(2)), thymine (C(5)H(6)N(2)O(2)), guanine (C(5)H(5)N(5)O), glycine (C(2)H(5)NO(2)), and alanine (C(3)H(7)NO(2)). Adenine (C(5)H(5)N(5)) was detected by GC-MS in isotopically labeled samples. The remaining prebiotic molecules were detected in unlabeled samples only and may have been affected by contamination in the chamber. These results demonstrate that prebiotic molecules can be formed by the high-energy chemistry similar to that which occurs in planetary upper atmospheres and therefore identifies a new source of prebiotic material, potentially increasing the range of planets where life could begin.
Simulated JWST/NIRISS Transit Spectroscopy of Anticipated TESS Planets Compared to Select Discoveries from Space-Based and Ground-Based Surveys

NASA Astrophysics Data System (ADS)

Louie, Dana; Deming, Drake; Albert, Loic; Bouma, Luke; Bean, Jacob; Lopez-Morales, Mercedes

2018-01-01

The Transiting Exoplanet Survey Satellite (TESS) will embark in 2018 on a 2-year wide-field survey mission of most of the celestial sky, discovering over a thousand super-Earth and sub-Neptune-sized exoplanets potentially suitable for follow-up observations using the James Webb Space Telescope (JWST). Bouma et al. (2017) and Sullivan et al. (2015) used Monte Carlo simulations to predict the properties of the planetary systems that TESS is likely to detect, basing their simulations upon Kepler-derived planet occurrence rates and photometric performance models for the TESS cameras. We employed a JWST Near InfraRed Imager and Slitless Spectrograph (NIRISS) simulation tool to estimate the signal-to-noise (S/N) that JWST/NIRISS will attain in transmission spectroscopy of these anticipated TESS discoveries, and we then compared the S/N for anticipated TESS discoveries to our estimates of S/N for 18 known exoplanets. We analyzed the sensitivity of our results to planetary composition, cloud cover, and presence of an observational noise floor. We find that only a few anticipated TESS discoveries in the terrestrial planet regime will result in better JWST/NIRISS S/N than currently known exoplanets, such as the TRAPPIST-1 planets, GJ1132b, or LHS1140b. However, we emphasize that this outcome is based upon Kepler-derived occurrence rates, and that co-planar compact systems (e.g. TRAPPIST-1) were not included in predicting the anticipated TESS planet yield. Furthermore, our results show that several hundred anticipated TESS discoveries in the super-Earth and sub-Neptune regime will produce S/N higher than currently known exoplanets such as K2-3b or K2-3c. We apply our results to estimate the scope of a JWST follow-up observation program devoted to mapping the transition region between high molecular weight and primordial planetary atmospheres.

Chemical evolution of Titan’s aerosol analogues under VUV irradiation

NASA Astrophysics Data System (ADS)

Carrasco, Nathalie; Gavilan, Lisseth; Tigrine, Sarah; Vettier, Ludovic; Nahon, Laurent; Pernot, Pascal

2017-10-01

Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan’s ionosphere [1].After production in the ionosphere, Titan’s aerosols evolve through microphysics during their sedimentation down to Titan’s surface [2]. Starting with a few nanomers size in the upper atmosphere, they reach a fractal structure of a few hundreds nanometers close to the surface [3]. During sedimentation, aerosols are also submitted to solar irradiation. As laboratory analogs of Titan’s atmospheric aerosols (tholins) show a strong UV absorption [4], we suspect that VUV irradiation could also induce a chemical evolution of Titan’s aerosols during their descent in Titan’s atmosphere.The aim of this work ist to simulate the irradiation process occuring on the aerosols in Titan’s atmosphere and to address whether this irradiation impacts the chemical composition of the organic solids. First aerosol analogues were produced in a N2-CH4 plasma discharge as thin organic films of a few hundreds of nanometers thick [5]. Then those were irradiated at Lyman-α wavelength, the strongest VUV line in the solar spectrum, with a high photon flux on a synchrotron VUV beamline. We will present and discuss the significant chemical evolutions observed on the analogues after VUV irradiation by mid-IR absorption spectroscopy.[1] Waite et al. (2009) Science , 316, p. 870[2] Lavvas et al. (2011) Astrophysical Journal, 728:80[3] Tomasko et al. (2008) Planetary and Space Science, 56, p. 669[4] Mahjoub et al. (2012) Icarus 221, P. 670[5] Carrasco et al. (2016) Planetary and Space Science, 128, p. 52
The Next Generation of Mars-GRAM and Its Role in the Autonomous Aerobraking Development Plan

NASA Technical Reports Server (NTRS)

Justh, Hilary L.; Justus, Carl G.; Ramey, Holly S.

2011-01-01

The Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM 2010 is currently being used to develop the onboard atmospheric density estimator that is part of the Autonomous Aerobraking Development Plan. In previous versions, Mars-GRAM was less than realistic when used for sensitivity studies for Thermal Emission Spectrometer (TES) MapYear=0 and large optical depth values, such as tau=3. A comparison analysis has been completed between Mars-GRAM, TES and data from the Planetary Data System (PDS) resulting in updated coefficients for the functions relating density, latitude, and longitude of the sun. The adjustment factors are expressed as a function of height (z), Latitude (Lat) and areocentric solar longitude (Ls). The latest release of Mars-GRAM 2010 includes these adjustment factors that alter the in-put data from MGCM and MTGCM for the Mapping Year 0 (user-controlled dust) case. The greatest adjustment occurs at large optical depths such as tau greater than 1. The addition of the adjustment factors has led to better correspondence to TES Limb data from 0-60 km as well as better agreement with MGS, ODY and MRO data at approximately 90-135 km. Improved simulations utilizing Mars-GRAM 2010 are vital to developing the onboard atmospheric density estimator for the Autonomous Aerobraking Development Plan. Mars-GRAM 2010 was not the only planetary GRAM utilized during phase 1 of this plan; Titan-GRAM and Venus-GRAM were used to generate density data sets for Aerobraking Design Reference Missions. These data sets included altitude profiles (both vertical and along a trajectory), GRAM perturbations (tides, gravity waves, etc.) and provided density and scale height values for analysis by other Autonomous Aero-braking team members.
Earth as an extrasolar planet: Earth model validation using EPOXI earth observations.

PubMed

Robinson, Tyler D; Meadows, Victoria S; Crisp, David; Deming, Drake; A'hearn, Michael F; Charbonneau, David; Livengood, Timothy A; Seager, Sara; Barry, Richard K; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Wellnitz, Dennis D

2011-06-01

The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be used to simulate Earth's time-dependent brightness and spectral properties for wavelengths from the far ultraviolet to the far infrared. Key Words: Astrobiology-Extrasolar terrestrial planets-Habitability-Planetary science-Radiative transfer. Astrobiology 11, 393-408.
Modeling light scattering by mineral dust particles using spheroids

NASA Astrophysics Data System (ADS)

Merikallio, Sini; Nousiainen, Timo

Suspended dust particles have a considerable influence on light scattering in both terrestrial and planetary atmospheres and can therefore have a large effect on the interpretation of remote sensing measurements. Assuming dust particles to be spherical is known to produce inaccurate results when modeling optical properties of real mineral dust particles. Yet this approximation is widely used for its simplicity. Here, we simulate light scattering by mineral dust particles using a distribution of model spheroids. This is done by comparing scattering matrices calculated from a dust optical database of Dubovik et al. [2006] with those measured in the laboratory by Volten et al. [2001]. Wavelengths of 441,6 nm and 632,8 nm and refractive indexes of Re = 1.55 -1.7 and Im = 0.001i -0.01i were adopted in this study. Overall, spheroids are found to fit the measurements significantly better than Mie spheres. Further, we confirm that the shape distribution parametrization developed in Nousiainen et al. (2006) significantly improves the accuracy of simulated single-scattering for small mineral dust particles. The spheroid scheme should therefore yield more reliable interpretations of remote sensing data from dusty planetary atmospheres. While the spheroidal scheme is superior to spheres in remote sensing applications, its performance is far from perfect especially for samples with large particles. Thus, additional advances are clearly possible. Further studies of the Martian atmosphere are currently under way. Dubovik et al. (2006) Application of spheroid models to account for aerosol particle nonspheric-ity in remote sensing of desert dust, JGR, Vol. 111, D11208 Volten et al. (2001) Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm, JGR, Vol. 106, No. D15, pp. 17375-17401 Nousiainen et al. (2006) Light scattering modeling of small feldspar aerosol particles using polyhedral prisms and spheroids, JQSRT 101, pp. 471-487
Supporting ITM Missions by Observing System Simulation Experiments: Initial Design, Challenges and Perspectives

NASA Astrophysics Data System (ADS)

Yudin, V. A.; England, S.; Matsuo, T.; Wang, H.; Immel, T. J.; Eastes, R.; Akmaev, R. A.; Goncharenko, L. P.; Fuller-Rowell, T. J.; Liu, H.; Solomon, S. C.; Wu, Q.

2014-12-01

We review and discuss the capability of novel configurations of global community (WACCM-X and TIME-GCM) and planned-operational (WAM) models to support current and forthcoming space-borne missions to monitor the dynamics and composition of the Ionosphere-Thermosphere-Mesosphere (ITM) system. In the specified meteorology model configuration of WACCM-X, the lower atmosphere is constrained by operational analyses and/or short-term forecasts provided by the Goddard Earth Observing System (GEOS-5) of GMAO/NASA/GSFC. With the terrestrial weather of GEOS-5 and updated model physics, WACCM-X simulations are capable to reproduce the observed signatures of the perturbed wave dynamics and ion-neutral coupling during recent (2006-2013) stratospheric warming events, short-term, annual and year-to-year variability of prevailing flows, planetary waves, tides, and composition. With assimilation of the NWP data in the troposphere and stratosphere the planned-operational configuration of WAM can also recreate the observed features of the ITM day-to-day variability. These "terrestrial-weather" driven whole atmosphere simulations, with day-to-day variable solar and geomagnetic inputs, can provide specification of the background state (first guess) and errors for the inverse algorithms of forthcoming NASA ITM missions, such as ICON and GOLD. With two different viewing geometries (sun-synchronous, for ICON and geostationary for GOLD) these missions promise to perform complimentary global observations of temperature, winds and constituents to constrain the first-principle space weather forecast models. The paper will discuss initial designs of Observing System Simulation Experiments (OSSE) in the coupled simulations of TIME-GCM/WACCM-X/GEOS5 and WAM/GIP. As recognized, OSSE represent an excellent learning tool for designing and evaluating observing capabilities of novel sensors. The choice of assimilation schemes, forecast and observational errors will be discussed along with challenges and perspectives to constrain fast-varying dynamics of tides and planetary waves by observations made from sun-synchronous and geostationary space-borne platforms. We will also discuss how correlative space-borne and ground-based observations can evaluate OSSE results.
Formation of solar system analogues - I. Looking for initial conditions through a population synthesis analysis

NASA Astrophysics Data System (ADS)

Ronco, M. P.; Guilera, O. M.; de Elía, G. C.

2017-11-01

Population synthesis models of planetary systems developed during the last ˜15 yr could reproduce several of the observables of the exoplanet population, and also allowed us to constrain planetary formation models. We present our planet formation model, which calculates the evolution of a planetary system during the gaseous phase. The code incorporates relevant physical phenomena for the formation of a planetary system, like photoevaporation, planet migration, gas accretion, water delivery in embryos and planetesimals, a detailed study of the orbital evolution of the planetesimal population, and the treatment of the fusion between embryos, considering their atmospheres. The main goal of this work, unlike other works of planetary population synthesis, is to find suitable scenarios and physical parameters of the disc to form Solar system analogues. We are specially interested in the final planet distributions, and in the final surface density, eccentricity and inclination profiles for the planetesimal population. These final distributions will be used as initial conditions for N-body simulations to study the post-oligarchic formation in a second work. We then consider different formation scenarios, with different planetesimal sizes and different type I migration rates. We find that Solar system analogues are favoured in massive discs, with low type I migration rates, and small planetesimal sizes. Besides, those rocky planets within their habitables zones are dry when discs dissipate. At last, the final configurations of Solar system analogues include information about the mass and semimajor axis of the planets, water contents, and the properties of the planetesimal remnants.
Wakefield acceleration in planetary atmospheres: A possible source of MeV electrons. The collisionless case

NASA Astrophysics Data System (ADS)

Arrayás, M.; Cubero, D.; Montanya, J.; Seviour, R.; Trueba, J. L.

2018-07-01

Intense electromagnetic pulses interacting with a plasma can create a wake of plasma oscillations. Electrons trapped in such oscillations can be accelerated under certain conditions to very high energies. We study the optimal conditions for the wakefield acceleration to produce MeV electrons in planetary plasmas under collisionless conditions. The conditions for the optimal plasma densities can be found in the Earth atmosphere at higher altitudes than 10-15 km, which are the altitudes where lightning leaders can take place.
The Behavior of the Atmosphere in the Desert Planetary Boundary Layer.

DTIC Science & Technology

1983-06-30

i5962 THE BEHAVIOR OF THE ATMOSPHERE IN THE DESERT PL NET RY 1/i. BOUNDARY LAVERMU BEN-GURION UNIV OF THE NEGEV SEDE BOGER (ISRAEL) JACOB BLAUST...DESERT PLANETARY BOUNDARY LAYER Louis Berkofsky The Jacob Blaustein Institute for Desert Research Ben-Gurion University of the Negev Sede Boqer Campus...TASK- nm insl1tute for esert Research AREA A WORK UNiT NUMBERS Ben-Gurion University of the Negev Sede Boqer Campus 84990, Israel F- 3 / St
Model-Atmosphere Spectra of Central Stars of Planetary Nebulae - Access via the Virtual Observatory Service TheoSSA

NASA Astrophysics Data System (ADS)

Rauch, T.; Reindl, N.

2014-04-01

In the framework of the Virtual Observatory (VO), the German Astrophysical Virtual Observatory GAVO project provides easy access to theoretical spectral energy distributions (SEDs) within the registered GAVO service TheoSSA (http://dc.g-vo.org/theossa). TheoSSA is based on the well established Tübingen NLTE Model-Atmosphere Package (TMAP) for hot, compact stars. This includes central stars of planetary nebulae. We show examples of TheoSSA in operation.
Spectroscopy and reactions of molecules important in chemical evolution

NASA Technical Reports Server (NTRS)

Becker, R. S.

1974-01-01

The research includes: (1) hot hydrogen atom reactions in terms of the nature of products produced, mechanism of the reactions and the implication and application of such reactions for molecules existing in interstellar clouds, in planetary atmospheres, and in chemical evolution; (2) photochemical reactions that can lead to molecules important in chemical evolution, interstellar clouds and as constituents in planetary atmospheres; and (3) spectroscopic and theoretical properties of biomolecules and their precursors and where possible, use these to understand their photochemical behavior.
Automatic quality assessment of planetary images

NASA Astrophysics Data System (ADS)

Sidiropoulos, P.; Muller, J.-P.

2015-10-01

A significant fraction of planetary images are corrupted beyond the point that much scientific meaning can be extracted. For example, transmission errors result in missing data which is unrecoverable. The available planetary image datasets include many such "bad data", which both occupy valuable scientific storage resources and create false impressions about planetary image availability for specific planetary objects or target areas. In this work, we demonstrate a pipeline that we have developed to automatically assess the quality of planetary images. Additionally, this method discriminates between different types of image degradation, such as low-quality originating from camera flaws or low-quality triggered by atmospheric conditions, etc. Examples of quality assessment results for Viking Orbiter imagery will be also presented.
Process engineering with planetary ball mills.

PubMed

Burmeister, Christine Friederike; Kwade, Arno

2013-09-21

Planetary ball mills are well known and used for particle size reduction on laboratory and pilot scales for decades while during the last few years the application of planetary ball mills has extended to mechanochemical approaches. Processes inside planetary ball mills are complex and strongly depend on the processed material and synthesis and, thus, the optimum milling conditions have to be assessed for each individual system. The present review focuses on the insight into several parameters like properties of grinding balls, the filling ratio or revolution speed. It gives examples of the aspects of grinding and illustrates some general guidelines to follow for modelling processes in planetary ball mills in terms of refinement, synthesis' yield and contamination from wear. The amount of energy transferred from the milling tools to the powder is significant and hardly measurable for processes in planetary ball mills. Thus numerical simulations based on a discrete-element-method are used to describe the energy transfer to give an adequate description of the process by correlation with experiments. The simulations illustrate the effect of the geometry of planetary ball mills on the energy entry. In addition the imaging of motion patterns inside a planetary ball mill from simulations and video recordings is shown.
Probability of US Heat Waves Affected by a Subseasonal Planetary Wave Pattern

NASA Technical Reports Server (NTRS)

Teng, Haiyan; Branstator, Grant; Wang, Hailan; Meehl, Gerald A.; Washington, Warren M.

2013-01-01

Heat waves are thought to result from subseasonal atmospheric variability. Atmospheric phenomena driven by tropical convection, such as the Asian monsoon, have been considered potential sources of predictability on subseasonal timescales. Mid-latitude atmospheric dynamics have been considered too chaotic to allow significant prediction skill of lead times beyond the typical 10-day range of weather forecasts. Here we use a 12,000-year integration of an atmospheric general circulation model to identify a pattern of subseasonal atmospheric variability that can help improve forecast skill for heat waves in the United States. We find that heat waves tend to be preceded by 15-20 days by a pattern of anomalous atmospheric planetary waves with a wavenumber of 5. This circulation pattern can arise as a result of internal atmospheric dynamics and is not necessarily linked to tropical heating.We conclude that some mid-latitude circulation anomalies that increase the probability of heat waves are predictable beyond the typical weather forecast range.
How Does the Shape of the Stellar Spectrum Affect the Raman Scattering Features in the Albedo of Exoplanets?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oklopčić, Antonija; Hirata, Christopher M.; Heng, Kevin, E-mail: oklopcic@astro.caltech.edu

The diagnostic potential of the spectral signatures of Raman scattering, imprinted in planetary albedo spectra at short optical wavelengths, has been demonstrated in research on planets in the solar system, and has recently been proposed as a probe of exoplanet atmospheres, complementary to albedo studies at longer wavelengths. Spectral features caused by Raman scattering offer insight into the properties of planetary atmospheres, such as the atmospheric depth, composition, and temperature, as well as the possibility of detecting and spectroscopically identifying spectrally inactive species, such as H{sub 2} and N{sub 2}, in the visible wavelength range. Raman albedo features, however, dependmore » on both the properties of the atmosphere and the shape of the incident stellar spectrum. Identical planetary atmospheres can produce very different albedo spectra depending on the spectral properties of the host star. Here we present a set of geometric albedo spectra calculated for atmospheres with H{sub 2}/He, N{sub 2}, and CO{sub 2} composition, irradiated by different stellar types ranging from late A to late K stars. Prominent albedo features caused by Raman scattering appear at different wavelengths for different types of host stars. We investigate how absorption due to the alkali elements sodium and potassium may affect the intensity of Raman features, and we discuss the preferred strategies for detecting Raman features in future observations.« less
Sensitivity of turbine-height wind speeds to parameters in planetary boundary-layer and surface-layer schemes in the weather research and forecasting model

DOE PAGES

Yang, Ben; Qian, Yun; Berg, Larry K.; ...

2016-07-21

We evaluate the sensitivity of simulated turbine-height wind speeds to 26 parameters within the Mellor–Yamada–Nakanishi–Niino (MYNN) planetary boundary-layer scheme and MM5 surface-layer scheme of the Weather Research and Forecasting model over an area of complex terrain. An efficient sampling algorithm and generalized linear model are used to explore the multiple-dimensional parameter space and quantify the parametric sensitivity of simulated turbine-height wind speeds. The results indicate that most of the variability in the ensemble simulations is due to parameters related to the dissipation of turbulent kinetic energy (TKE), Prandtl number, turbulent length scales, surface roughness, and the von Kármán constant. Themore » parameter associated with the TKE dissipation rate is found to be most important, and a larger dissipation rate produces larger hub-height wind speeds. A larger Prandtl number results in smaller nighttime wind speeds. Increasing surface roughness reduces the frequencies of both extremely weak and strong airflows, implying a reduction in the variability of wind speed. All of the above parameters significantly affect the vertical profiles of wind speed and the magnitude of wind shear. Lastly, the relative contributions of individual parameters are found to be dependent on both the terrain slope and atmospheric stability.« less
Sensitivity of turbine-height wind speeds to parameters in planetary boundary-layer and surface-layer schemes in the weather research and forecasting model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Ben; Qian, Yun; Berg, Larry K.

We evaluate the sensitivity of simulated turbine-height wind speeds to 26 parameters within the Mellor–Yamada–Nakanishi–Niino (MYNN) planetary boundary-layer scheme and MM5 surface-layer scheme of the Weather Research and Forecasting model over an area of complex terrain. An efficient sampling algorithm and generalized linear model are used to explore the multiple-dimensional parameter space and quantify the parametric sensitivity of simulated turbine-height wind speeds. The results indicate that most of the variability in the ensemble simulations is due to parameters related to the dissipation of turbulent kinetic energy (TKE), Prandtl number, turbulent length scales, surface roughness, and the von Kármán constant. Themore » parameter associated with the TKE dissipation rate is found to be most important, and a larger dissipation rate produces larger hub-height wind speeds. A larger Prandtl number results in smaller nighttime wind speeds. Increasing surface roughness reduces the frequencies of both extremely weak and strong airflows, implying a reduction in the variability of wind speed. All of the above parameters significantly affect the vertical profiles of wind speed and the magnitude of wind shear. Lastly, the relative contributions of individual parameters are found to be dependent on both the terrain slope and atmospheric stability.« less
Sensitivity of the Atmospheric Response to Warm Pool El Nino Events to Modeled SSTs and Future Climate Forcings

NASA Technical Reports Server (NTRS)

Hurwitz, Margaret M.; Garfinkel, Chaim I.; Newman, Paul A.; Oman, Luke D.

2013-01-01

Warm pool El Nino (WPEN) events are characterized by positive sea surface temperature (SST) anomalies in the central equatorial Pacific. Under present-day climate conditions, WPEN events generate poleward propagating wavetrains and enhance midlatitude planetary wave activity, weakening the stratospheric polar vortices. The late 21st century extratropical atmospheric response to WPEN events is investigated using the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM), version 2. GEOSCCM simulations are forced by projected late 21st century concentrations of greenhouse gases (GHGs) and ozone-depleting substances (ODSs) and by SSTs and sea ice concentrations from an existing ocean-atmosphere simulation. Despite known ocean-atmosphere model biases, the prescribed SST fields represent a best estimate of the structure of late 21st century WPEN events. The future Arctic vortex response is qualitatively similar to that observed in recent decades but is weaker in late winter. This response reflects the weaker SST forcing in the Nino 3.4 region and subsequently weaker Northern Hemisphere tropospheric teleconnections. The Antarctic stratosphere does not respond to WPEN events in a future climate, reflecting a change in tropospheric teleconnections: The meridional wavetrain weakens while a more zonal wavetrain originates near Australia. Sensitivity simulations show that a strong poleward wavetrain response to WPEN requires a strengthening and southeastward extension of the South Pacific Convergence Zone; this feature is not captured by the late 21st century modeled SSTs. Expected future increases in GHGs and decreases in ODSs do not affect the polar stratospheric responses to WPEN.
Julie Lundquist | NREL

Science.gov Websites

professor in the Department of Atmospheric and Oceanic Sciences at the University of Colorado at Boulder . Her research group uses observational and computational approaches to understand atmospheric M.S., Astrophysical, Planetary, and Atmospheric Science, University of Colorado at Boulder
Atmospheric Excitation of Planetary Normal Modes

NASA Technical Reports Server (NTRS)

Tanimoto, Toshiro

2001-01-01

The objectives of this study were to: (1) understand the phenomenon of continuous free oscillations of the Earth and (2) examine the idea of using this phenomenon for planetary seismology. We first describe the results on (1) and present our evaluations of the idea (2) in the final section. In 1997, after almost forty years since the initial attempt by Benioff et al, continuous free oscillations of the Earth were discovered. Spheroidal fundamental modes between 2 and 7 millihertz are excited continuously with acceleration amplitudes of about 0.3-0.5 nanogals. The signal is now commonly found in virtually all data recorded by STS-1 type broadband seismometers at quiet sites. Seasonal variation in amplitude and the existence of two coupled modes between the atmosphere and the solid Earth support that these oscillations are excited by the atmosphere. Stochastic excitation due to atmospheric turbulence is a favored mechanism, providing a good match between theory and data. The atmosphere has ample energy to support this theory because excitation of these modes require only 500-10000 W whereas the atmosphere contains about 117 W of kinetic energy. An application of this phenomenon includes planetary seismology, because other planets may be oscillating due to atmospheric excitation. The interior structure of planets could be learned by determining the eigenfrequencies in the continuous free oscillations. It is especially attractive to pursue this idea for tectonically quiet planets, since quakes may be too infrequent to be recorded by seismic instruments.
Laboratory studies, analysis, and interpretation of the spectra of hydrocarbons present in planetary atmospheres including cyanoacetylene, acetylene, propane, and ethane

NASA Technical Reports Server (NTRS)

Blass, William E.; Daunt, Stephen J.; Peters, Antoni V.; Weber, Mark C.

1990-01-01

Combining broadband Fourier transform spectrometers (FTS) from the McMath facility at NSO and from NRC in Ottawa and narrow band TDL data from the laboratories with computational physics techniques has produced a broad range of results for the study of planetary atmospheres. Motivation for the effort flows from the Voyager/IRIS observations and the needs of Voyager analysis for laboratory results. In addition, anticipation of the Cassini mission adds incentive to pursue studies of observed and potentially observable constituents of planetary atmospheres. Current studies include cyanoacetylene, acetylene, propane, and ethane. Particular attention is devoted to cyanoacetylen (H3CN) which is observed in the atmosphere of Titan. The results of a high resolution infrared laboratory study of the line positions of the 663, 449, and 22.5/cm fundamental bands are presented. Line position, reproducible to better than 5 MHz for the first two bands, are available for infrared astrophysical searches. Intensity and broadening studies are in progress. Acetylene is a nearly ubiquitous atmospheric constituent of the outer planets and Titan due to the nature of methane photochemistry. Results of ambient temperature absolute intensity measurements are presented for the fundamental and two two-quantum hotband in the 730/cm region. Low temperature hotband intensity and linewidth measurements are planned.

On the Causes of and Long Term Changes in Eurasian Heat Waves

NASA Technical Reports Server (NTRS)

Schubert, Siegfried; Wang, Hailan; Koster, Randal; Suarez, Max

2012-01-01

The MERRA reanalysis, other observations, and the GEOS-S model have been used to diagnose the causes of Eurasian heat waves including the recent extreme events that occurred in Europe during 2003 and in Russia during 2010. The results show that such extreme events are an amplification of natural patterns of atmospheric variability (in this case a particular large-scale atmospheric planetary wave) that develop over the Eurasian continent as a result of internal atmospheric forcing. The amplification occurs when the wave occasionally becomes locked in place for several weeks to months resulting in extreme heat and drying with the location depending on the phase of the upper atmospheric wave. Model experiments suggest that forcing from both the ocean (SST) and land playa role phase-locking the waves. An ensemble of very long GEOS-S model simulations (spanning the 20th century) forced with observed SST and greenhouse gases show that the model is capable of generating very similar heat waves, and that they have become more extreme in the last thirty years as a result of the overall warming of the Asian continent.
GRAM-86 - FOUR DIMENSIONAL GLOBAL REFERENCE ATMOSPHERE MODEL

NASA Technical Reports Server (NTRS)

Johnson, D.

1994-01-01

The Four-D Global Reference Atmosphere program was developed from an empirical atmospheric model which generates values for pressure, density, temperature, and winds from surface level to orbital altitudes. This program can be used to generate altitude profiles of atmospheric parameters along any simulated trajectory through the atmosphere. The program was developed for design applications in the Space Shuttle program, such as the simulation of external tank re-entry trajectories. Other potential applications would be global circulation and diffusion studies, and generating profiles for comparison with other atmospheric measurement techniques, such as satellite measured temperature profiles and infrasonic measurement of wind profiles. The program is an amalgamation of two empirical atmospheric models for the low (25km) and the high (90km) atmosphere, with a newly developed latitude-longitude dependent model for the middle atmosphere. The high atmospheric region above 115km is simulated entirely by the Jacchia (1970) model. The Jacchia program sections are in separate subroutines so that other thermosphericexospheric models could easily be adapted if required for special applications. The atmospheric region between 30km and 90km is simulated by a latitude-longitude dependent empirical model modification of the latitude dependent empirical model of Groves (1971). Between 90km and 115km a smooth transition between the modified Groves values and the Jacchia values is accomplished by a fairing technique. Below 25km the atmospheric parameters are computed by the 4-D worldwide atmospheric model of Spiegler and Fowler (1972). This data set is not included. Between 25km and 30km an interpolation scheme is used between the 4-D results and the modified Groves values. The output parameters consist of components for: (1) latitude, longitude, and altitude dependent monthly and annual means, (2) quasi-biennial oscillations (QBO), and (3) random perturbations to partially simulate the variability due to synoptic, diurnal, planetary wave, and gravity wave variations. Quasi-biennial and random variation perturbations are computed from parameters determined by various empirical studies and are added to the monthly mean values. The UNIVAC version of GRAM is written in UNIVAC FORTRAN and has been implemented on a UNIVAC 1110 under control of EXEC 8 with a central memory requirement of approximately 30K of 36 bit words. The GRAM program was developed in 1976 and GRAM-86 was released in 1986. The monthly data files were last updated in 1986. The DEC VAX version of GRAM is written in FORTRAN 77 and has been implemented on a DEC VAX 11/780 under control of VMS 4.X with a central memory requirement of approximately 100K of 8 bit bytes. The GRAM program was originally developed in 1976 and later converted to the VAX in 1986 (GRAM-86). The monthly data files were last updated in 1986.
Prediction of Rare Transitions in Planetary Atmosphere Dynamics Between Attractors with Different Number of Zonal Jets

NASA Astrophysics Data System (ADS)

Bouchet, F.; Laurie, J.; Zaboronski, O.

2012-12-01

We describe transitions between attractors with either one, two or more zonal jets in models of turbulent atmosphere dynamics. Those transitions are extremely rare, and occur over times scales of centuries or millennia. They are extremely hard to observe in direct numerical simulations, because they require on one hand an extremely good resolution in order to simulate accurately the turbulence and on the other hand simulations performed over an extremely long time. Those conditions are usually not met together in any realistic models. However many examples of transitions between turbulent attractors in geophysical flows are known to exist (paths of the Kuroshio, Earth's magnetic field reversal, atmospheric flows, and so on). Their study through numerical computations is inaccessible using conventional means. We present an alternative approach, based on instanton theory and large deviations. Instanton theory provides a way to compute (both numerically and theoretically) extremely rare transitions between turbulent attractors. This tool, developed in field theory, and justified in some cases through the large deviation theory in mathematics, can be applied to models of turbulent atmosphere dynamics. It provides both new theoretical insights and new type of numerical algorithms. Those algorithms can predict transition histories and transition rates using numerical simulations run over only hundreds of typical model dynamical time, which is several order of magnitude lower than the typical transition time. We illustrate the power of those tools in the framework of quasi-geostrophic models. We show regimes where two or more attractors coexist. Those attractors corresponds to turbulent flows dominated by either one or more zonal jets similar to midlatitude atmosphere jets. Among the trajectories connecting two non-equilibrium attractors, we determine the most probable ones. Moreover, we also determine the transition rates, which are several of magnitude larger than a typical time determined from the jet structure. We discuss the medium-term generalization of those results to models with more complexity, like primitive equations or GCMs.
Midwinter Disturbances in the Middle Atmosphere

NASA Technical Reports Server (NTRS)

Labitzke, K.

1984-01-01

The Middle Atmosphere is coupled to the troposphere during winter because planetary scale waves can propagate upwards if the prevailing winds are from the west. It is during this time of the year that the well-known midwinter disturbances are observed which ultimately affect the whole of the Middle Atmosphere. The mechanism of these disturbances is not completely understood. The large-scale circulation features up to the upper mesosphere are investigated to demonstrate the synoptic-scale behavior of the midwinter disturbances. Ground-based and satellite observations are combined. The interannual variability of the disturbances is discussed briefly. It is shown that the QBO (Quasi Biennial Oscillation) of the equatorial stratosphere appears to modulate the planetary waves during the northern winters, in the troposphere as well as in the Middle Atmosphere.
On the role of electron-driven processes in planetary atmospheres and comets

NASA Astrophysics Data System (ADS)

Campbell, L.; Brunger, M. J.

2009-11-01

After the presence of ionized layers in the Earth's atmosphere was inferred, it took 50 years to quantitatively understand them. The electron density could not be accounted for until Sir David Bates first suggested (along with Sir Harrie Massey) that the main electron-loss process was dissociative recombination with molecular ions, and he and colleagues then developed a theory to predict those rates of dissociative recombination. However, electron impact processes, particularly excitation, have been considered insignificant in most situations, in both planetary and cometary atmospheres. Here we describe cases where recent calculations have shown that electron impact excitation of molecules is important, suggesting that, just as in the time of Sir David Bates, electron-driven processes remain fundamental to our quantitative understanding of atmospheric and cometary phenomena.
A study of planetary meteorology

NASA Technical Reports Server (NTRS)

Ohring, G.

1973-01-01

Inversion techniques are applied to the few earth based observations of the Jovian emission spectrum to obtain directly the profiles of atmospheric temperature and ammonia abundance. The temperature profile is characterized by a definite tropopause region with a temperature of about 115K and a stratospheric region in which the temperature slowly increases with altitude. The derived ammonia profile indicates the presence of a saturated ammonia layer with a base temperature of approximately 14OK. The concept is described deducing the temperature and constituent profile of a planetary atmosphere from orbiter measurements of the planet's IR limb radiance profile. Analysis of the weighting functions for the Martian atmosphere indicates that a limb radiance profile in the 15 micron CO2 band can be used to determine the Martian atmospheric temperature profile from 20 to 60 km.
Tools to Manage and Access the NOMAD Data

NASA Astrophysics Data System (ADS)

Trompet, L.; Vandaele, A. C.; Thomas, I. R.

2018-04-01

The NOMAD instrument on-board the ExoMars spacecraft will generate a large amount of data of the atmosphere of Mars. The Planetary Aeronomy Division at IASB is willing to make their tools and these data available to the whole planetary science community.
Development of artificial meteor for observation of upper atmosphere

NASA Astrophysics Data System (ADS)

Watanabe, Masaki; Sahara, Hironori; Abe, Shinsuke; Watanabe, Takeo; Nojiri, Yuta; Okajima, Lena

2016-04-01

This study proposes a method for the observation of the upper atmosphere using an artificial meteor injected by a mass driver installed on a microsatellite. The mass driver injects a pill at a velocity of 200 m/s and deorbits it into the atmosphere. The emission of the pill can then be observed from the ground at the necessary time and location. This approach could contribute to a better understanding of the global environment as well as different aspects of astronomy and planetary science. To realize the proposed method, the required size and emission of the pill have to be determined. Therefore, we conducted flow-field simulations, spectroscopic estimations, and an experiment on an artificial meteor in the arc heater wind tunnel at the Institute of Space and Astronautical Science in the Japan Aerospace Exploration Agency (ISAS/JAXA). From the results, we confirmed that the light emission could be observed as a shooting star by the naked eye and thus verified the feasibility of the method.
Climate warming due to increasing atmospheric CO2 - Simulations with a multilayer coupled atmosphere-ocean seasonal energy balance model

NASA Technical Reports Server (NTRS)

Li, Peng; Chou, Ming-Dah; Arking, Albert

1987-01-01

The transient response of the climate to increasing CO2 is studied using a modified version of the multilayer energy balance model of Peng et al. (1982). The main characteristics of the model are described. Latitudinal and seasonal distributions of planetary albedo, latitude-time distributions of zonal mean temperatures, and latitudinal distributions of evaporation, water vapor transport, and snow cover generated from the model and derived from actual observations are analyzed and compared. It is observed that in response to an atmospheric doubling of CO2, the model reaches within 1/e of the equilibrium response of global mean surface temperature in 9-35 years for the probable range of vertical heat diffusivity in the ocean. For CO2 increases projected by the National Research Council (1983), the model's transient response in annually and globally averaged surface temperatures is 60-75 percent of the corresponding equilibrium response, and the disequilibrium increases with increasing heat diffusivity of the ocean.
Prospect of life on cold planets with low atmospheric pressures

NASA Astrophysics Data System (ADS)

Pavlov, A. A.; Vdovina, M.

2009-12-01

Stable liquid water on the surface of a planet has been viewed as the major requirement for a habitable planet. Such approach would exclude planets with low atmospheric pressures and cold mean surface temperatures (like present Mars) as potential candidates for extraterrestrial life search. Here we explore a possibility of the liquid water formation in the extremely shallow (1-3 cm) subsurface layer under low atmospheric pressures (0.1-10 mbar) and low average surface temperatures (~-30 C). During brief periods of simulated daylight warming the shallow subsurface ice sublimates, the water vapor can diffuse through the porous surface layer of soil temporarily producing supersaturated conditions in the soil, which lead to the formation of liquid films. We show that non-extremophile terrestrial microorganisms (Vibrio sp.) can grow and reproduce under such conditions. The necessary conditions for metabolism and reproduction are the sublimation of ground ice through a thin layer of soil and short episodes of warm temperatures at the planetary surface.
Climate, ecosystems, and planetary futures: The challenge to predict life in Earth system models.

PubMed

Bonan, Gordon B; Doney, Scott C

2018-02-02

Many global change stresses on terrestrial and marine ecosystems affect not only ecosystem services that are essential to humankind, but also the trajectory of future climate by altering energy and mass exchanges with the atmosphere. Earth system models, which simulate terrestrial and marine ecosystems and biogeochemical cycles, offer a common framework for ecological research related to climate processes; analyses of vulnerability, impacts, and adaptation; and climate change mitigation. They provide an opportunity to move beyond physical descriptors of atmospheric and oceanic states to societally relevant quantities such as wildfire risk, habitat loss, water availability, and crop, fishery, and timber yields. To achieve this, the science of climate prediction must be extended to a more multifaceted Earth system prediction that includes the biosphere and its resources. Copyright © 2018, American Association for the Advancement of Science.
CFD applications in hypersonic flight

NASA Technical Reports Server (NTRS)

Edwards, T. A.

1992-01-01

Design studies are underway for a variety of hypersonic flight vehicles. The National Aero-Space Plane will provide a reusable, single-stage-to-orbit capability for routine access to low earth orbit. Flight-capable satellites will dip into the atmosphere to maneuver to new orbits, while planetary probes will decelerate at their destination by atmospheric aerobraking. To supplement limited experimental capabilities in the hypersonic regime, CFD is being used to analyze the flow about these configurations. The governing equations include fluid dynamic as well as chemical species equations, which are solved with robust upwind differencing schemes. Examples of CFD applications to hypersonic vehicles suggest an important role this technology will play in the development of future aerospace systems. The computational resources needed to obtain solutions are large, but various strategies are being exploited to reduce the time required for complete vehicle simulations.
Dynamics of atmospheres with a non-dilute condensible component

PubMed Central

Ding, Feng

2016-01-01

The diversity of characteristics for the host of recently discovered exoplanets opens up a great deal of fertile new territory for geophysical fluid dynamics, particularly when the fluid flow is coupled to novel thermodynamics, radiative transfer or chemistry. In this paper, we survey one of these new areas—the climate dynamics of atmospheres with a non-dilute condensible component, defined as the situation in which a condensible component of the atmosphere makes up a substantial fraction of the atmospheric mass within some layer. Non-dilute dynamics can occur for a wide range of condensibles, generically applying near both the inner and the outer edges of the conventional habitable zone and in connection with runaway greenhouse phenomena. It also applies in a wide variety of other planetary circumstances. We first present a number of analytical results developing some key features of non-dilute atmospheres, and then show how some of these features are manifest in simulations with a general circulation model adapted to handle non-dilute atmospheres. We find that non-dilute atmospheres have weak horizontal temperature gradients even for rapidly rotating planets, and that their circulations are largely barotropic. The relative humidity of the condensible component tends towards 100% as the atmosphere becomes more non-dilute, which has important implications for runaway greenhouse thresholds. Non-dilute atmospheres exhibit a number of interesting organized convection features, for which there is not yet any adequate theoretical understanding. PMID:27436980
IN SITU ACCRETION OF HYDROGEN-RICH ATMOSPHERES ON SHORT-PERIOD SUPER-EARTHS: IMPLICATIONS FOR THE KEPLER-11 PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikoma, M.; Hori, Y., E-mail: ikoma@eps.s.u-tokyo.ac.jp, E-mail: yasunori.hori@nao.ac.jp

2012-07-01

Motivated by recent discoveries of low-density super-Earths with short orbital periods, we have investigated in situ accretion of H-He atmospheres on rocky bodies embedded in dissipating warm disks, by simulating quasi-static evolution of atmospheres that connect to the ambient disk. We have found that the atmospheric evolution has two distinctly different outcomes, depending on the rocky body's mass: while the atmospheres on massive rocky bodies undergo runaway disk-gas accretion, those on light rocky bodies undergo significant erosion during disk dispersal. In the atmospheric erosion, the heat content of the rocky body that was previously neglected plays an important role. Wemore » have also realized that the atmospheric mass is rather sensitive to disk temperature in the mass range of interest in this study. Our theory is applied to recently detected super-Earths orbiting Kepler-11 to examine the possibility that the planets are rock-dominated ones with relatively thick H-He atmospheres. The application suggests that the in situ formation of the relatively thick H-He atmospheres inferred by structure modeling is possible only under restricted conditions, namely, relatively slow disk dissipation and/or cool environments. This study demonstrates that low-density super-Earths provide important clues to understanding of planetary accretion and disk evolution.« less
Dynamics of atmospheres with a non-dilute condensible component.

PubMed

Pierrehumbert, Raymond T; Ding, Feng

2016-06-01

The diversity of characteristics for the host of recently discovered exoplanets opens up a great deal of fertile new territory for geophysical fluid dynamics, particularly when the fluid flow is coupled to novel thermodynamics, radiative transfer or chemistry. In this paper, we survey one of these new areas-the climate dynamics of atmospheres with a non-dilute condensible component, defined as the situation in which a condensible component of the atmosphere makes up a substantial fraction of the atmospheric mass within some layer. Non-dilute dynamics can occur for a wide range of condensibles, generically applying near both the inner and the outer edges of the conventional habitable zone and in connection with runaway greenhouse phenomena. It also applies in a wide variety of other planetary circumstances. We first present a number of analytical results developing some key features of non-dilute atmospheres, and then show how some of these features are manifest in simulations with a general circulation model adapted to handle non-dilute atmospheres. We find that non-dilute atmospheres have weak horizontal temperature gradients even for rapidly rotating planets, and that their circulations are largely barotropic. The relative humidity of the condensible component tends towards 100% as the atmosphere becomes more non-dilute, which has important implications for runaway greenhouse thresholds. Non-dilute atmospheres exhibit a number of interesting organized convection features, for which there is not yet any adequate theoretical understanding.
Reflection spectra of solids of planetary interest

NASA Technical Reports Server (NTRS)

Sill, G. T.

1973-01-01

The spectra of solids are reproduced which might be found on the surfaces of planetary bodies or as solid condensates in the upper planetary atmosphere. Among these are spectra of various iron compounds of interest in the study of the clouds of Venus. Other spectra are included of various sulfides, some at low temperature, relevant to the planet Jupiter. Meteorite and coal abstracts are also included, to illustrate dark carbon compounds.
Reflection spectra of solids of planetary interest

NASA Technical Reports Server (NTRS)

Sill, G. T.; Carm, O.

1973-01-01

This paper reproduces the spectra of solids which might be found on the surfaces of planetary bodies or as solid condensates in the upper planetary atmosphere. Among these are spectra of various iron compounds of interest in the study of the clouds of Venus. Other spectra (some at low temperature) are included for various sulfides relevant to the planet Jupiter. Meteorite and coal spectra are also included to illustrate dark carbon compounds.
Space and planetary environment criteria guidelines for use in space vehicle development, 1971 revision

NASA Technical Reports Server (NTRS)

Smith, R. E. (Editor)

1971-01-01

A consolidation of natural environment data is presented for use as design criteria guidelines in space and planetary exploration vehicle development programs. In addition to information in the disciplinary areas of aeronomy, radiation, geomagnetism, astrodynamic constants, and meteoroids for the earth's environment above 90 kilometers, interplanetary space, and the planetary environments, the upper atmosphere model currently recommended for use at MSFC is discussed in detail.
The Importance of Planetary Rotation Period for Ocean Heat Transport

PubMed Central

Stevens, D.; Joshi, M.

2014-01-01

Abstract The climate and, hence, potential habitability of a planet crucially depends on how its atmospheric and ocean circulation transports heat from warmer to cooler regions. However, previous studies of planetary climate have concentrated on modeling the dynamics of atmospheres, while dramatically simplifying the treatment of oceans, which neglects or misrepresents the effect of the ocean in the total heat transport. Even the majority of studies with a dynamic ocean have used a simple so-called aquaplanet that has no continental barriers, which is a configuration that dramatically changes the ocean dynamics. Here, the significance of the response of poleward ocean heat transport to planetary rotation period is shown with a simple meridional barrier—the simplest representation of any continental configuration. The poleward ocean heat transport increases significantly as the planetary rotation period is increased. The peak heat transport more than doubles when the rotation period is increased by a factor of ten. There are also significant changes to ocean temperature at depth, with implications for the carbon cycle. There is strong agreement between the model results and a scale analysis of the governing equations. This result highlights the importance of both planetary rotation period and the ocean circulation when considering planetary habitability. Key Words: Exoplanet—Oceans—Rotation—Climate—Habitability. Astrobiology 14, 645–650. PMID:25041658
Planetary Protection Considerations for Life Support and Habitation Systems

NASA Technical Reports Server (NTRS)

Barta, Daniel J.; Hogan, John A.

2010-01-01

Life support systems for future human missions beyond low Earth orbit may include a combination of existing hardware components and advanced technologies. Discipline areas for technology development include atmosphere revitalization, water recovery, solid waste management, crew accommodations, food production, thermal systems, environmental monitoring, fire protection and radiation protection. Life support systems will be influenced by in situ resource utilization (ISRU), crew mobility and the degree of extravehicular activity. Planetary protection represents an additional set of requirements that technology developers have generally not considered. Planetary protection guidelines will affect the kind of operations, processes, and functions that can take place during future exploration missions, including venting and discharge of liquids and solids, ejection of wastes, use of ISRU, requirements for cabin atmospheric trace contaminant concentrations, cabin leakage and restrictions on what materials, organisms, and technologies that may be brought on missions. Compliance with planetary protection requirements may drive development of new capabilities or processes (e.g. in situ sterilization, waste containment, contaminant measurement) and limit or prohibit certain kinds of operations or processes (e.g. unfiltered venting). Ultimately, there will be an effect on mission costs, including the mission trade space. Planetary protection requirements need to be considered early in technology development programs. It is expected that planetary protection will have a major impact on technology selection for future missions.

Development of an autonomous unmanned aerial system for atmospheric data collection and research

NASA Astrophysics Data System (ADS)

Lee, Andrew; Hanlon, David; Sakai, Ricardo; Morris, Vernon; Demoz, Belay; Gadsden, S. Andrew

2016-05-01

This paper addresses the use of unmanned aerial systems (UAS) to carry out atmospheric data collection and studies. An important area of research is the study of the chemistry and physics of Earth's planetary boundary layer (PBL). The PBL, also known as the atmospheric boundary layer (ABL), is the lowest part of the atmosphere and its behavior is directly influenced by its contact with the planetary surface. Sampling of the PBL is performed in a timely and periodic manner. Currently, sensors and uncontrollable balloons are used to obtain relevant data and information. This method is cumbersome and can be ineffective in obtaining consistent environmental data. This paper proposes the use of autonomous UAS' to study the atmosphere in an effort to improve the efficiency and accuracy of the sampling process. The UAS setup and design is provided, and preliminary data collection information is shared.
Planetary Evolution, Habitability and Life

NASA Astrophysics Data System (ADS)

Tilman, Spohn; Breuer, Doris; de Vera, Jean-Pierre; Jaumann, Ralf; Kuehrt, Ekkehard; Möhlmann, Diedrich; Rauer, Heike; Richter, Lutz

A Helmholtz Alliance has been established to study the interactions between life and the evo-lution of planets. The approach goes beyond current studies in Earth-System Sciences by including the entire planet from the atmosphere to the deep interior, going beyond Earth to include other Earth-like planets such as Mars and Venus and satellites in the solar system where ecosystems may exist underneath thick ice shells,considering other solar systems. The approach includes studies of the importance of plate tectonics and other tectonic regimes such as single plate tectonics for the development and for sustaining life and asks the question: If life can adapt to a planet, can a planet adapt to life? Can life be seen as a geological process and if so, can life shape the conditions on a planet such that life can flourish? The vision goes beyond the solar system by including the challenges that life would face in other solar systems. The Alliance uses theoretical modelling of feedback cycles and coupled planetary atmosphere and interior processes. These models are based on the results of remote sensing of planetary surfaces and atmospheres, laboratory studies on (meteorite) samples from other planets and on studies of life under extreme conditions. The Alliance uses its unique capabilities in remote sensing and in-situ exploration to prepare for empirical studies of the parameters affecting habitability. The Alliance aims to establish a network infrastructure in Germany to enable the most ad-vanced research in planetary evolution studies by including life as a planetary process. Finding extraterrestrial life is a task of fundamental importance to mankind, and its fulfilment will be philosophically profound. Evaluating the interactions between planetary evolution and life will help to put the evolution of our home planet (even anthropogenic effects) into perspective.
No One's Home: the Fate of Carbon on Lifeless Earths

NASA Astrophysics Data System (ADS)

Neveu, Marc

Although several thousands of exoplanets are now known, including many terrestrial planets, their possible geology and climates remain poorly understood and understudied. Yet, understanding how elements such as carbon are cycled between a planet's interior, surface, and atmosphere is crucial to predict how lifeless planets operate and, by contrast, be able to detect deviations from abiotic backgrounds due to biology, the holy grail of exoplanet science. As a first, feasible step towards the difficult, long-term goal of understanding how key reactive elements (H, C, N, O, S) are cycled in the atmospheres, surfaces, and interiors of terrestrial exoplanets through time, we propose to carry out a self-consistent theoretical study of the fate of carbon in the atmospheres and at the surfaces of Earth-like, lifeless exoplanets. We will: 1. Model the near-surface geochemistry and geophysics of the carbon cycle to determine net carbon gas fluxes as a function of terrestrial planet size and redox conditions; 2. Model the atmospheric fate of carbon species as a function of stellar input; 3. Perform simulations that self-consistently combine geological and atmospheric processes; 4. Convert resulting atmospheric compositions to spectra to be archived as a public database for use by observers. We will track the abiotic fate of carbon and its atmospheric expression on Earth-like planets as a function of three key parameters: planet size, surface and atmospheric redox conditions, and stellar irradiation. To do so, we will further develop and use state-of-theart planetary geological ("Geo") and atmospheric ("Atmos") models. We have previously developed a code that couples geophysical evolution and water-rock geochemistry (Neveu et al. 2015, GRL 42, 10197). Using this code, we will calculate the speciation of carbon species versus depth in subaerial oceans, their possible incorporation into the crust by water-rock interaction at the seafloor or by subduction of sediments, and outgassing as a function of temperature, pressure, and fluid/rock composition. We will expand this code with benchmarked parameterizations of land and seafloor weathering and outgassing rates. This modeling will result in detailed boundary conditions to be implemented into an existing atmospheric photochemical-climate model (DomagalGoldman et al. 2014, ApJ 792, 90). The atmospheric model will be used to predict species mixing ratios from net surface fluxes, given planetary and stellar parameters. The models will be benchmarked against what is known of the surfaces and atmospheres of the Earth (present and prior to atmospheric oxygenation) and Titan. Atmospheric model outputs will be fed back into the geological model in combined simulations of carbon cycling. We will investigate in detail the mutual feedbacks between geological and atmospheric processes, so far understudied for terrestrial exoplanets. The resulting atmospheric compositions will be converted to predicted exoplanet spectra using the Spectral Mapping Atmospheric Radiative Transfer model (SMART; Meadows & Crisp 1996, JGR 101, 4595). This grid of spectra will be made freely available to the exoplanet community. This proposal is relevant to the Exoplanets Research Program (E.3) objectives, as it "supports directly the scientific goals of advancing our knowledge and understanding of exoplanetary systems." It involves the "characterization of exoplanets (including their surfaces, interiors, and atmospheres) [...] including the determination of their compositions, dynamics, energetics, and chemical behaviors." This investigation will also advance "understanding the chemical and physical processes of exoplanets (including the state and evolution of their surfaces, interiors, and atmospheres)." Furthermore, this proposal is not "aimed at investigating the habitability of an exoplanet" and therefore not relevant to the Habitable Worlds program element (E.4).
Entry, Descent, and Landing With Propulsive Deceleration: Supersonic Retropropulsion Wind Tunnel Testing

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2012-01-01

The future exploration of the Solar System will require innovations in transportation and the use of entry, descent, and landing (EDL) systems at many planetary landing sites. The cost of space missions has always been prohibitive, and using the natural planetary and planet s moons atmosphere for entry, descent, and landing can reduce the cost, mass, and complexity of these missions. This paper will describe some of the EDL ideas for planetary entry and survey the overall technologies for EDL that may be attractive for future Solar System missions. Future EDL systems may include an inflatable decelerator for the initial atmospheric entry and an additional supersonic retro-propulsion (SRP) rocket system for the final soft landing. As part of those efforts, NASA began to conduct experiments to gather the experimental data to make informed decisions on the "best" EDL options. A model of a three engine retro-propulsion configuration with a 2.5 in. diameter sphere-cone aeroshell model was tested in the NASA Glenn 1- by 1-Foot Supersonic Wind Tunnel (SWT). The testing was conducted to identify potential blockage issues in the tunnel, and visualize the rocket flow and shock interactions during supersonic and hypersonic entry conditions. Earlier experimental testing of a 70 Viking-like (sphere-cone) aeroshell was conducted as a baseline for testing of a supersonic retro-propulsion system. This baseline testing defined the flow field around the aeroshell and from this comparative baseline data, retro-propulsion options will be assessed. Images and analyses from the SWT testing with 300- and 500-psia rocket engine chamber pressures are presented here. The rocket engine flow was simulated with a non-combusting flow of air.
Planetary Astronomy

NASA Technical Reports Server (NTRS)

Stern, S. Alan

1998-01-01

This 1-year project was an augmentation grant to my NASA Planetary Astronomy grant. With the awarded funding, we accomplished the following tasks: (1) Conducted two NVK imaging runs in conjunction with the ILAW (International Lunar Atmosphere Week) Observing Campaigns in 1995 and 1997. In the first run, we obtained repeated imaging sequences of lunar Na D-line emission to better quantify the temporal variations detected in earlier runs. In the second run we obtained extremely high resolution (R=960.000) Na line profiles using the 4m AAT in Australia. These data are being analyzed under our new 3-year Planetary Astronomy grant. (2) Reduced, analyzed, and published our March 1995 spectroscopic dataset to detect (or set stringent upper limits on) Rb. Cs, Mg. Al. Fe, Ba, Ba. OH, and several other species. These results were reported in a talk at the LPSC and in two papers: (1) A Spectroscopic Survey of Metallic Abundances in the Lunar Atmosphere. and (2) A Search for Magnesium in the Lunar Atmosphere. Both reprints are attached. Wrote up an extensive, invited Reviews of Geophysics review article on advances in the study of the lunar atmosphere. This 70-page article, which is expected to appear in print in 1999, is also attached.
Studies of Tidal and Planetary Wave Variability in the Middle Atmosphere using UARS and Correlative MF Radar Data

NASA Technical Reports Server (NTRS)

Fritts, David C.

1996-01-01

The goals of this research effort have been to use MF radar and UARS/HRDI wind measurements for correlative studies of large-scale atmospheric dynamics, focusing specifically on the tidal and various planetary wave structures occurring in the middle atmosphere. We believed that the two data sets together would provide the potential for much more comprehensive studies than either by itself, since they jointly would allow the removal of ambiguities in wave structure that are difficult to resolve with either data set alone. The joint data were to be used for studies of wave structure, variability, and the coupling of these motions to mean and higher-frequency motions.
High Resolution Infrared Spectroscopy of Molecules of Terrestrial and Planetary Interest

NASA Technical Reports Server (NTRS)

Freedman, Richard S.

2001-01-01

In collaboration with the laboratory spectroscopy group of the Ames Atmospheric Physics Research Branch (SGP), high resolution infrared spectra of molecules that are of importance for the dynamics of the earth's and other planets' atmospheres were acquired using the SGP high resolution Fourier transform spectrometer and gas handling apparatus. That data, along with data acquired using similar instrumentation at the Kitt Peak National Observatory was analyzed to determine the spectral parameters for each of the rotationally resolved transitions for each molecule. Those parameters were incorporated into existing international databases (e.g. HITRANS and GEISA) so that field measurements could be converted into quantitative information regarding the physical and chemical structures of earth and planetary atmospheres.
Comparison of ocean surface solar irradiance in the GLA General Circulation Model and satellite-based calculations

NASA Technical Reports Server (NTRS)

Chertock, Beth; Sud, Y. C.

1993-01-01

A global, 7-year satellite-based record of ocean surface solar irradiance (SSI) is used to assess the realism of ocean SSI simulated by the nine-layer Goddard Laboratory for Atmospheres (GLA) General Circulation Model (GCM). January and July climatologies of net SSI produced by the model are compared with corresponding satellite climatologies for the world oceans between 54 deg N and 54 deg S. This comparison of climatologies indicates areas of strengths and weaknesses in the GCM treatment of cloud-radiation interactions, the major source of model uncertainty. Realism of ocean SSI is also important for applications such as incorporating the GLA GCM into a coupled ocean-atmosphere GCM. The results show that the GLA GCM simulates too much SSI in the extratropics and too little in the tropics, especially in the summer hemisphere. These discrepancies reach magnitudes of 60 W/sq m and more. The discrepancies are particularly large in the July case off the western coast of North America. Positive and negative discrepancies in SSI are shown to be consistent with discrepancies in planetary albedo.
Constraints on Wave Drag Parameterization Schemes for Simulating the Quasi-Biennial Oscillation. Part I: Gravity Wave Forcing.

NASA Astrophysics Data System (ADS)

Campbell, Lucy J.; Shepherd, Theodore G.

2005-12-01

Parameterization schemes for the drag due to atmospheric gravity waves are discussed and compared in the context of a simple one-dimensional model of the quasi-biennial oscillation (QBO). A number of fundamental issues are examined in detail, with the goal of providing a better understanding of the mechanism by which gravity wave drag can produce an equatorial zonal wind oscillation. The gravity wave driven QBOs are compared with those obtained from a parameterization of equatorial planetary waves. In all gravity wave cases, it is seen that the inclusion of vertical diffusion is crucial for the descent of the shear zones and the development of the QBO. An important difference between the schemes for the two types of waves is that in the case of equatorial planetary waves, vertical diffusion is needed only at the lowest levels, while for the gravity wave drag schemes it must be included at all levels. The question of whether there is downward propagation of influence in the simulated QBOs is addressed. In the gravity wave drag schemes, the evolution of the wind at a given level depends on the wind above, as well as on the wind below. This is in contrast to the parameterization for the equatorial planetary waves in which there is downward propagation of phase only. The stability of a zero-wind initial state is examined, and it is determined that a small perturbation to such a state will amplify with time to the extent that a zonal wind oscillation is permitted.
The Planetary Virtual Observatory and Laboratory (PVOL) and its integration into the Virtual European Solar and Planetary Access (VESPA)

NASA Astrophysics Data System (ADS)

Hueso, R.; Juaristi, J.; Legarreta, J.; Sánchez-Lavega, A.; Rojas, J. F.; Erard, S.; Cecconi, B.; Le Sidaner, Pierre

2018-01-01

Since 2003 the Planetary Virtual Observatory and Laboratory (PVOL) has been storing and serving publicly through its web site a large database of amateur observations of the Giant Planets (Hueso et al., 2010a). These images are used for scientific research of the atmospheric dynamics and cloud structure on these planets and constitute a powerful resource to address time variable phenomena in their atmospheres. Advances over the last decade in observation techniques, and a wider recognition by professional astronomers of the quality of amateur observations, have resulted in the need to upgrade this database. We here present major advances in the PVOL database, which has evolved into a full virtual planetary observatory encompassing also observations of Mercury, Venus, Mars, the Moon and the Galilean satellites. Besides the new objects, the images can be tagged and the database allows simple and complex searches over the data. The new web service: PVOL2 is available online in http://pvol2.ehu.eus/.
Emergence of life from multicomponent mixtures of chemicals: the case for experiments with cycling physicochemical gradients.

PubMed

Spitzer, Jan

2013-04-01

The emergence of life from planetary multicomponent mixtures of chemicals is arguably the most complicated and least understood natural phenomenon. The fact that living cells are non-equilibrium systems suggests that life can emerge only from non-equilibrium chemical systems. From an astrobiological standpoint, non-equilibrium chemical systems arise naturally when solar irradiation strikes rotating surfaces of habitable planets: the resulting cycling physicochemical gradients persistently drive planetary chemistries toward "embryonic" living systems and an eventual emergence of life. To better understand the factors that lead to the emergence of life, I argue for cycling non-equilibrium experiments with multicomponent chemical systems designed to represent the evolving chemistry of Hadean Earth ("prebiotic soups"). Specifically, I suggest experimentation with chemical engineering simulators of Hadean Earth to observe and analyze (i) the appearances and phase separations of surface active and polymeric materials as precursors of the first "cell envelopes" (membranes) and (ii) the accumulations, commingling, and co-reactivity of chemicals from atmospheric, oceanic, and terrestrial locations.
United States Temperature and Precipitation Extremes: Phenomenology, Large-Scale Organization, Physical Mechanisms and Model Representation

NASA Astrophysics Data System (ADS)

Black, R. X.

2017-12-01

We summarize results from a project focusing on regional temperature and precipitation extremes over the continental United States. Our project introduces a new framework for evaluating these extremes emphasizing their (a) large-scale organization, (b) underlying physical sources (including remote-excitation and scale-interaction) and (c) representation in climate models. Results to be reported include the synoptic-dynamic behavior, seasonality and secular variability of cold waves, dry spells and heavy rainfall events in the observational record. We also study how the characteristics of such extremes are systematically related to Northern Hemisphere planetary wave structures and thus planetary- and hemispheric-scale forcing (e.g., those associated with major El Nino events and Arctic sea ice change). The underlying physics of event onset are diagnostically quantified for different categories of events. Finally, the representation of these extremes in historical coupled climate model simulations is studied and the origins of model biases are traced using new metrics designed to assess the large-scale atmospheric forcing of local extremes.
Convection driven zonal flows and vortices in the major planets.

PubMed

Busse, F. H.

1994-06-01

The dynamical properties of convection in rotating cylindrical annuli and spherical shells are reviewed. Simple theoretical models and experimental simulations of planetary convection through the use of the centrifugal force in the laboratory are emphasized. The model of columnar convection in a cylindrical annulus not only serves as a guide to the dynamical properties of convection in rotating sphere; it also is of interest as a basic physical system that exhibits several dynamical properties in their most simple form. The generation of zonal mean flows is discussed in some detail and examples of recent numerical computations are presented. The exploration of the parameter space for the annulus model is not yet complete and the theoretical exploration of convection in rotating spheres is still in the beginning phase. Quantitative comparisons with the observations of the dynamics of planetary atmospheres will have to await the consideration in the models of the effects of magnetic fields and the deviations from the Boussinesq approximation.
Evaluating Models Of The Neutral, Barotropic Planetary Boundary Layer Using Integral Measures: Part Ii. Modelling Observed Conditions

NASA Astrophysics Data System (ADS)

Hess, G. D.; Garratt, J. R.

The steady-state, horizontally homogeneous, neutral, barotropiccase forms the foundation of our theoretical understanding of the planetary boundary layer (PBL).While simple analytical models and first-order closure models simulate atmospheric observationsof this case well, more sophisticated models, in general, do not. In this paperwe examine how well three higher-order closure models, E - - l, E - l, and LRR - l,which have been especially modified for PBL applications, perform in predicting the behaviour of thecross-isobaric angle 0, the geostrophic drag coefficient Cg, and the integral of the dissipationrate over the boundary layer, as a function of the surface Rossby number Ro. For comparison we alsoexamine the performance of three first-order closure mixing-length models, two proposed byA. K. Blackadar and one by H. H. Lettau, and the performance of the standard model forsecond-order closure and a modification of it designed to reduce the overprediction of turbulence inthe upper part of the boundary layer.
Thermal shallow water models of geostrophic turbulence in Jovian atmospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warneford, Emma S., E-mail: emma.warneford@maths.ox.ac.uk; Dellar, Paul J., E-mail: dellar@maths.ox.ac.uk

2014-01-15

Conventional shallow water theory successfully reproduces many key features of the Jovian atmosphere: a mixture of coherent vortices and stable, large-scale, zonal jets whose amplitude decreases with distance from the equator. However, both freely decaying and forced-dissipative simulations of the shallow water equations in Jovian parameter regimes invariably yield retrograde equatorial jets, while Jupiter itself has a strong prograde equatorial jet. Simulations by Scott and Polvani [“Equatorial superrotation in shallow atmospheres,” Geophys. Res. Lett. 35, L24202 (2008)] have produced prograde equatorial jets through the addition of a model for radiative relaxation in the shallow water height equation. However, their modelmore » does not conserve mass or momentum in the active layer, and produces mid-latitude jets much weaker than the equatorial jet. We present the thermal shallow water equations as an alternative model for Jovian atmospheres. These equations permit horizontal variations in the thermodynamic properties of the fluid within the active layer. We incorporate a radiative relaxation term in the separate temperature equation, leaving the mass and momentum conservation equations untouched. Simulations of this model in the Jovian regime yield a strong prograde equatorial jet, and larger amplitude mid-latitude jets than the Scott and Polvani model. For both models, the slope of the non-zonal energy spectra is consistent with the classic Kolmogorov scaling, and the slope of the zonal energy spectra is consistent with the much steeper spectrum observed for Jupiter. We also perform simulations of the thermal shallow water equations for Neptunian parameter values, with a radiative relaxation time scale calculated for the same 25 mbar pressure level we used for Jupiter. These Neptunian simulations reproduce the broad, retrograde equatorial jet and prograde mid-latitude jets seen in observations. The much longer radiative time scale for the colder planet Neptune explains the transition from a prograde to a retrograde equatorial jet, while the broader jets are due to the deformation radius being a larger fraction of the planetary radius.« less
Emission and Chemical Transformation of Biogenic Volatile Organic Compounds (echo)

NASA Astrophysics Data System (ADS)

Koppmann, R.; Hoffmann, T.; Kesselmeier, J.; Schatzmann, M.

Forests are complex sources of biogenic volatile organic compounds (VOC) in the planetary boundary layer. The impact of biogenic VOC on tropospheric photochem- istry, air quality, and the formation of secondary products affects our climate on a regional and global scale but is far from being understood. A considerable lack of knowledge exists concerning a forest stand as a net source of reactive trace com- pounds, which are transported directly into the planetary boundary layer (PBL). In particular, little is known about the amounts of VOC which are processed within the canopy. The goal of ECHO, which is presented in this poster, is to investigate these questions and to improve our understanding of biosphere-atmosphere interactions and their effects on the PBL. The investigation of emissions, chemical processing and vertical transport of biogenic VOC will be carried out in and above a mixed forest stand in Jülich, Germany. A large set of trace gases, free radicals and meteorologi- cal parameters will be measured at different heights in and above the canopy, covering concentrations of VOC, CO, O3, organic nitrates und NOx as well as organic aerosols. For the first time concentration profiles of OH, HO2, RO2 und NO3 radicals will be measured as well together with the actinic UV radiation field and photolysis frequen- cies of all relevant radical precursors (O3, NO2, peroxides, oxygenated VOC). The different tasks of the field experiments will be supported by simulation experiments investigating the primary emission and the uptake of VOC by the plants in stirred tank reactors, soil parameters and soil emissions in lysimeter experiments, and the chem- ical processing of the trace gases as observed in and above the forest stand in the atmosphere simulation chamber SAPHIR. The planning and interpretation of the field experiments is supported by simulations of the field site in a wind tunnel.
Sensitivity of the Mid-Winter Arctic Stratosphere to QBO Width in a Simplified Chemistry-Climate Model

NASA Technical Reports Server (NTRS)

Hurwitz, M. M.; Braesicke., P.; Pyle, J. A.

2011-01-01

In the stratosphere, equatorial winds continually alternate between easterly (westward) and westerly (eastward). This phenomenon is called the quasi-biennial oscillation (QBO). The average QBO cycle (Le. easterly to westerly to easterly) lasts approximately 27 months. Large-scale 'planetary' waves can only travel upward through the atmosphere when equatorial winds are westerly, and below a critical threshold. Thus, the amount of wave energy that reaches the middle atmosphere depends on the wind direction. When equatorial winds are easterly, wave energy is concentrated at higher latitudes, weakening the high-latitude eastward wind feature known as the 'polar jet' during the Northern Hemisphere winter season. Holton and Tan (1980) used atmospheric observations to show the dependence of the strength of the northern polar jet on the phase (easterly vs. westerly) of the QBO. This modeling study finds that the width of the quasi-biennial oscillation (QBO) varies from one cycle to the next, and that variation in QBO width may exert equal influence on the Arctic stratosphere as does the QBO wind direction. High latitude winds are weaker and ozone values are higher in a wide-QBO model simulation, as compared with a realistic simulation. This result implies that a relatively wider QBO acts like a preferential shift toward the easterly phase of the QBO.
Testing Atmospheric Retrieval Modeling Assumptions for Transiting Planet Atmospheres: Preparatory science for the James Webb Space Telescope and beyond.

NASA Astrophysics Data System (ADS)

Line, Michael

The field of transiting exoplanet atmosphere characterization has grown considerably over the past decade given the wealth of photometric and spectroscopic data from the Hubble and Spitzer space telescopes. In order to interpret these data, atmospheric models combined with Bayesian approaches are required. From spectra, these approaches permit us to infer fundamental atmospheric properties and how their compositions can relate back to planet formation. However, such approaches must make a wide range of assumptions regarding the physics/parameterizations included in the model atmospheres. There has yet to be a comprehensive investigation exploring how these model assumptions influence our interpretations of exoplanetary spectra. Understanding the impact of these assumptions is especially important since the James Webb Space Telescope (JWST) is expected to invest a substantial portion of its time observing transiting planet atmospheres. It is therefore prudent to optimize and enhance our tools to maximize the scientific return from the revolutionary data to come. The primary goal of the proposed work is to determine the pieces of information we can robustly learn from transiting planet spectra as obtained by JWST and other future, space-based platforms, by investigating commonly overlooked model assumptions. We propose to explore the following effects and how they impact our ability to infer exoplanet atmospheric properties: 1. Stellar/Planetary Uncertainties: Transit/occultation eclipse depths and subsequent planetary spectra are measured relative to their host stars. How do stellar uncertainties, on radius, effective temperature, metallicity, and gravity, as well as uncertainties in the planetary radius and gravity, propagate into the uncertainties on atmospheric composition and thermal structure? Will these uncertainties significantly bias our atmospheric interpretations? Is it possible to use the relative measurements of the planetary spectra to provide additional constraints on the stellar properties? 2. The "1D" Assumption: Atmospheres are inherently three-dimensional. Many exoplanet atmosphere models, especially within retrieval frameworks, assume 1D physics and chemistry when interpreting spectra. How does this "1D" atmosphere assumption bias our interpretation of exoplanet spectra? Do we have to consider global temperature variations such as day-night contrasts or hot spots? What about spatially inhomogeneous molecular abundances and clouds? How will this change our interpretations of phase resolved spectra? 3. Clouds/Hazes: Understanding how clouds/hazes impact transit spectra is absolutely critical if we are to obtain proper estimates of basic atmospheric quantities. How do the assumptions in cloud physics bias our inferences of molecular abundances in transmission? What kind of data (wavelengths, signal-to-noise, resolution) do we need to infer cloud composition, vertical extent, spatial distribution (patchy or global), and size distributions? The proposed work is relevant and timely to the scope of the NASA Exoplanet Research program. The proposed work aims to further develop the critical theoretical modeling tools required to rigorously interpret transiting exoplanet atmosphere data in order to maximize the science return from JWST and beyond. This work will serve as a benchmark study for defining the data (wavelength ranges, signal-to-noises, and resolutions) required from a modeling perspective to "characterize exoplanets and their atmospheres in order to inform target and operational choices for current NASA missions, and/or targeting, operational, and formulation data for future NASA observatories". Doing so will allow us to better "understand the chemical and physical processes of exoplanets (their atmospheres)" which will ultimately " improve understanding of the origins of exoplanetary systems" through robust planetary elemental abundance determinations.
The aurora as a source of planetary-scale waves in the middle atmosphere. [atmospheric turbulence caused by auroral energy absorption

NASA Technical Reports Server (NTRS)

Chiu, Y. T.; Straus, J. M.

1974-01-01

Photographs of global scale auroral forms taken by scanning radiometers onboard weather satellites in 1972 show that auroral bands exhibit well organized wave motion with typical zonal wave number of 5 or so. The scale size of these waves is in agreement with that of well organized neutral wind fields in the 150- to 200-km region during the geomagnetic storm of May 27, 1967. Further, the horizontal scale size revealed by these observations are in agreement with that of high altitude traveling ionospheric disturbances. It is conjectured that the geomagnetic storm is a source of planetary and synoptic scale neutral atmospheric waves in the middle atmosphere. Although there is, at present, no observation of substorm related waves of this scale size at mesospheric and stratospheric altitudes, the possible existence of a new source of waves of the proper scale size to trigger instabilities in middle atmospheric circulation systems may be significant in the study of lower atmospheric response to geomagnetic activity.
Composition/Structure/Dynamics of comet and planetary satellite atmospheres

NASA Technical Reports Server (NTRS)

Combi, Michael R. (Principal Investigator)

1995-01-01

This research program addresses two cases of tenuous planetary atmospheres: comets and Io. The comet atmospheric research seeks to analyze a set of spatial profiles of CN in comet Halley taken in a 7.4-day period in April 1986; to apply a new dust coma model to various observations; and to analyze observations of the inner hydrogen coma, which can be optically thick to the resonance scattering of Lyman-alpha radiation, with the newly developed approach that combines a spherical radiative transfer model with our Monte Carlo H coma model. The Io research seeks to understand the atmospheric escape from Io with a hybrid-kinetic model for neutral gases and plasma given methods and algorithms developed for the study of neutral gas cometary atmospheres and the earth's polar wind and plasmasphere. Progress is reported on cometary Hydrogen Lyman-alpha studies; time-series analysis of cometary spatial profiles; model analysis of the dust comae of comets; and a global kinetic atmospheric model of Io.

A survey of bimolecular ion-molecule reactions for use in modeling the chemistry of planetary atmospheres, cometary comae, and interstellar clouds

NASA Technical Reports Server (NTRS)

Anicich, V. G.; Huntress, W. T., Jr.

1986-01-01

All bimolecular positive ion-molecule reactions reported from 1965 to 1985 for temperatures below 1000 K are included in the present survey of those ion-molecule reactions pertinent to the chemistries of planetary atmospheres, cometary comae, and interstellar clouds. This survey is intended as an update of the first, by Huntress (1977). The tabular presentation is organized according to reactant ion, with cross-references for both the ionic and the neutral reactants as well as the ionic and neutral products.
From H.G. Wells to Unmanned Planetary Exploration

NASA Technical Reports Server (NTRS)

Boyd, John W.

2005-01-01

The possibility of planetary exploration has been a dream of the human race since Galileo discovered the moons of Jupiter in 1610. Visual sightings of bodies entering Earth s atmosphere have been made by Earth s inhabitants over the centuries. Over time, the many meteor showers (Leonid, Perseid) have provided dramatic evidence of the intense heat generated by a body entering Earth s atmosphere at hypervelocity speeds. More recently (in 1908), few viewed the Tunguska meteor that impacted in Siberia, but the destructive power on the countryside was awesome.
Analytical solution of the optimal three dimensional reentry problem using Chapman's exact equations

NASA Technical Reports Server (NTRS)

Vinh, N. X.; Busemann, A.; Culp, R. D.

1974-01-01

This paper presents the general solution for the optimal three dimensional aerodynamic control of a lifting vehicle entering a planetary atmosphere. A set of dimensionless variables is introduced, and the resulting exact equations of motion have the distinctive advantage that they are completely free of the physical characteristics of the vehicle. Furthermore, a general lift-drag polar is used to define the aerodynamic control. Hence, the results obtained apply to any type of vehicle of arbitrary weight, dimensions and shape, having an arbitrary polar and entering any planetary atmosphere.
Planetary entry experiments

NASA Technical Reports Server (NTRS)

Craig, Roger A.

1994-01-01

The final report summarizes the results from three research areas: (1) window design for the radiometric measurement of the forebody radiative heating experienced by atmospheric entry spaceraft; (2) survey of the current understanding of chemical species on selected solar system bodies and assess the importance of measurements with regard to vehicle environment and with regard to understanding of planetary atmospheres with emphasis on Venus, Mars, and Titan; and (3) measure and analyze the radiation (VUV to near-IR) from the shock heated gas cap of a blunt body in an Ames arc Jet wind-tunnel facility.
Regolith-Derived Heat Shield for Planetary Body Entry and Descent System with In-Situ Fabrication

NASA Technical Reports Server (NTRS)

Hogue, Michael D.; Mueller, Robert P.; Sibille, Laurent; Hintze, Paul E.; Rasky, Daniel J.

2012-01-01

High-mass planetary surface access is one of NASA's Grand Challenges involving entry, descent, and landing (EDL). Heat shields fabricated in-situ can provide a thermal protection system for spacecraft that routinely enter a planetary atmosphere. Fabricating the heat shield from extraterrestrial regolith will avoid the costs of launching the heat shield mass from Earth. This project will investigate three methods to fabricate heat shield using extraterrestrial regolith.
Origin of the solar system

NASA Technical Reports Server (NTRS)

Cameron, A. G. W.

1988-01-01

The current status of the classical model of solar-system formation is surveyed, reviewing the results of recent observational and theoretical investigations. Topics addressed include interstellar clouds, the collapse of interstellar gas, the primitive solar nebula, the formation of the sun, planetesimal accumulation, planetary accumulation, major planetary collisions, the development of planetary atmospheres, and comets. The relative merits of conflicting theories on many key problems are indicated, with reference to more detailed reviews in the literature.
Radiation Beamline Testbeds for the Simulation of Planetary and Spacecraft Environments for Human and Robotic Mission Risk Assessment

NASA Technical Reports Server (NTRS)

Wilkins, Richard

2010-01-01

The Center for Radiation Engineering and Science for Space Exploration (CRESSE) at Prairie View A&M University, Prairie View, Texas, USA, is establishing an integrated, multi-disciplinary research program on the scientific and engineering challenges faced by NASA and the international space community caused by space radiation. CRESSE focuses on space radiation research directly applicable to astronaut health and safety during future long term, deep space missions, including Martian, lunar, and other planetary body missions beyond low earth orbit. The research approach will consist of experimental and theoretical radiation modeling studies utilizing particle accelerator facilities including: 1. NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory; 2. Proton Synchrotron at Loma Linda University Medical Center; and 3. Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory. Specifically, CRESSE investigators are designing, developing, and building experimental test beds that simulate the lunar and Martian radiation environments for experiments focused on risk assessment for astronauts and instrumentation. The testbeds have been designated the Bioastronautics Experimental Research Testbeds for Environmental Radiation Nostrum Investigations and Education (BERT and ERNIE). The designs of BERT and ERNIE will allow for a high degree of flexibility and adaptability to modify experimental configurations to simulate planetary surface environments, planetary habitats, and spacecraft interiors. In the nominal configuration, BERT and ERIE will consist of a set of experimental zones that will simulate the planetary atmosphere (Solid CO2 in the case of the Martian surface.), the planetary surface, and sub-surface regions. These experimental zones can be used for dosimetry, shielding, biological, and electronic effects radiation studies in support of space exploration missions. BERT and ERNIE are designed to be compatible with the experimental areas associated with the above facilities. CRESSE has broad expertise in space radiation in the areas of space radiation environment modeling, Monte-Carlo radiation transport modeling, space radiation instrumentation and dosimetry, radiation effects on electronics, and multi-functional composite shielding materials. The BERT and ERNIE testbeds will be utilized in individual and collaborative research incorporating this expertise. The research goal is to maximize the technical readiness level (TRL) of radiation instrumentation for human and robotic missions, optimizing the return value of CRESSE for NASA exploration and international co-operative missions. Outcomes and knowledge from research utilizing BERT and ERNIE will be applied to a variety of scientific and engineering disciplines vital for safe and reliable execution of future space exploration missions, which can be negatively impacted by the space radiation environment. The testbeds will be central to a variety of university educational activities and educational goals of NASA. Specifically, BERT and ERNIE will enhance educational opportunities in science, technology, engineering and mathematics (STEM) disciplines for engineering and science students at PVAMU, a historically black college/university. Preliminary data on prototype testbed configurations, including simulated lunar regolith (JSC-1A stimulant based on Apollo 11 samples), regolith/polyethylene composites, and dry ice, will be presented to demonstrate the usefulness of BERT and ERNIE in radiation beam line experiments.
Radiation beamline testbeds for the simulation of planetary and spacecraft environments for human and robotic mission risk assessment

NASA Astrophysics Data System (ADS)

Wilkins, Richard

The Center for Radiation Engineering and Science for Space Exploration (CRESSE) at Prairie View A&M University, Prairie View, Texas, USA, is establishing an integrated, multi-disciplinary research program on the scientific and engineering challenges faced by NASA and the inter-national space community caused by space radiation. CRESSE focuses on space radiation research directly applicable to astronaut health and safety during future long term, deep space missions, including Martian, lunar, and other planetary body missions beyond low earth orbit. The research approach will consist of experimental and theoretical radiation modeling studies utilizing particle accelerator facilities including: 1. NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory; 2. Proton Synchrotron at Loma Linda University Med-ical Center; and 3. Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory. Specifically, CRESSE investigators are designing, developing, and building experimental test beds that simulate the lunar and Martian radiation environments for experiments focused on risk assessment for astronauts and instrumentation. The testbeds have been designated the Bioastronautics Experimental Research Testbeds for Environmental Radiation Nostrum Investigations and Education (BERT and ERNIE). The designs of BERT and ERNIE will allow for a high degree of flexibility and adaptability to modify experimental configurations to simulate planetary surface environments, planetary habitats, and spacecraft interiors. In the nominal configuration, BERT and ERIE will consist of a set of experimental zones that will simulate the planetary atmosphere (Solid CO2 in the case of the Martian surface.), the planetary surface, and sub-surface regions. These experimental zones can be used for dosimetry, shielding, biological, and electronic effects radiation studies in support of space exploration missions. BERT and ERNIE are designed to be compatible with the experimental areas associated with the above facilities. CRESSE has broad expertise in space radiation in the areas of space radiation environment modeling, Monte-Carlo radiation transport modeling, space radiation instrumentation and dosimetry, radiation effects on electronics, and multi-functional composite shielding materi-als. The BERT and ERNIE testbeds will be utilized in individual and collaborative research incorporating this expertise. The research goal is to maximize the technical readiness level (TRL) of radiation instrumentation for human and robotic missions, optimizing the return value of CRESSE for NASA exploration and international co-operative missions. Outcomes and knowledge from research utilizing BERT and ERNIE will be applied to a variety of scien-tific and engineering disciplines vital for safe and reliable execution of future space exploration missions, which can be negatively impacted by the space radiation environment. The testbeds will be central to a variety of university educational activities and educational goals of NASA. Specifically, BERT and ERNIE will enhance educational opportunities in science, technol-ogy, engineering and mathematics (STEM) disciplines for engineering and science students at PVAMU, a historically black college/university. Preliminary data on prototype testbed configurations, including simulated lunar regolith (JSC-1A stimulant based on Apollo 11 samples), regolith/polyethylene composites, and dry ice, will be presented to demonstrate the usefulness of BERT and ERNIE in radiation beam line experiments.
The final fate of planetary systems

NASA Astrophysics Data System (ADS)

Gaensicke, Boris

2015-12-01

The discovery of the first extra-solar planet around a main-sequence star in 1995 has changed the way we think about the Universe: our solar system is not unique. Twenty years later, we know that planetary systems are ubiquitous, orbit stars spanning a wide range in mass, and form in an astonishing variety of architectures. Yet, one fascinating aspect of planetary systems has received relatively little attention so far: their ultimate fate.Most planet hosts will eventually evolve into white dwarfs, Earth-sized stellar embers, and the outer parts of their planetary systems (in the solar system, Mars and beyond) can survive largely intact for billions of years. While scattered and tidally disrupted planetesimals are directly detected at a small number of white dwarfs in the form infrared excess, the most powerful probe for detecting evolved planetary systems is metal pollution of the otherwise pristine H/He atmospheres.I will present the results of a multi-cycle HST survey that has obtained COS observations of 136 white dwarfs. These ultraviolet spectra are exquisitely sensitive to the presence of metals contaminating the white atmosphere. Our sophisticated model atmosphere analysis demonstrates that at least 27% of all targets are currently accreting planetary debris, and an additional 29% have very likely done so in the past. These numbers suggest that planet formation around A-stars (the dominant progenitors of today's white dwarf population) is similarly efficient as around FGK stars.In addition to post-main sequence planetary system demographics, spectroscopy of the debris-polluted white dwarf atmospheres provides a direct window into the bulk composition of exo-planetesimals, analogous to the way we use of meteorites to determine solar-system abundances. Our ultraviolet spectroscopy is particularly sensitive to the detection of Si, a dominant rock-forming species, and we identify up to ten additional volatile and refractory elements in the most strongly contaminated white dwarfs. The derived bulk abundances unambiguously demonstrate the predominantly rocky nature of the accreted material, with two exceptions where we detect volatile-rich debris. The relative abundance ratios suggest a wide range of parent bodies, including both primitive asteroids and fragments from differentiated planetesimals. The growing number of detailed debris abundances can provide important observational constraints on planet formation models.
A Theoretical and Experimental Study of Emission Spectroscopy of Planetary Surfaces

NASA Astrophysics Data System (ADS)

Henderson, Bradley Gray

1995-01-01

This thesis explores the spectral emissivity of particulate materials on planetary surfaces through theoretical modeling and supporting laboratory and field investigations. In the first part of the thesis, I develop a Monte Carlo ray tracing model to calculate the directional and spectral emissivity and the polarization state of the radiation emitted from a particulate, isothermal surface for emission angles 0^circ-90^ circ and wavelengths 7-16 mu m. The results show that roughness and scattering significantly affect the character of the emitted radiation field and should be taken into account when interpreting the physical properties of a planetary surface from IR spectrophotometry or spectropolarimetry. The remainder of the thesis focuses on understanding near-surface thermal gradients and their effects on emission spectra for different planetary environments. These gradients are formed by radiative cooling in the top few hundred microns of low conductivity particulate materials on planetary surfaces with little or no atmosphere. I model the heat transfer by conduction and radiation in the top few millimeters of a planetary regolith for scattering and non-scattering media. In conjunction with the modeling, I measure emission spectra of fine-grained quartz in an environment chamber designed to simulate the conditions on other planetary surfaces. The results show that significant thermal gradients will form in the near surface of materials on the surface of the Moon and Mercury. Their presence increases spectral contrast and creates emission maxima in the transparent regions of the spectrum. Thermal gradients are shown to be responsible for the observed wavelength shifts of the Christiansen emission peak with variations in thermal conductivity and grain size. The results are also used to analyze recent telescopic spectra of the Moon and Mercury and can explain certain features seen in those data. Thermal gradients are shown to be minor for the surface of Mars and negligible on Earth. I conclude that the spectral effects created by near-surface thermal gradients are predictable and might even provide an extra source of information about the physical nature of a planetary surface, and mid-IR emission spectroscopy should therefore prove to be useful for remote sensing of airless bodies.
Potential biosignatures in super-Earth atmospheres II. Photochemical responses.

PubMed

Grenfell, J L; Gebauer, S; Godolt, M; Palczynski, K; Rauer, H; Stock, J; von Paris, P; Lehmann, R; Selsis, F

2013-05-01

Spectral characterization of super-Earth atmospheres for planets orbiting in the habitable zone of M dwarf stars is a key focus in exoplanet science. A central challenge is to understand and predict the expected spectral signals of atmospheric biosignatures (species associated with life). Our work applies a global-mean radiative-convective-photochemical column model assuming a planet with an Earth-like biomass and planetary development. We investigated planets with gravities of 1g and 3g and a surface pressure of 1 bar around central stars with spectral classes from M0 to M7. The spectral signals of the calculated planetary scenarios have been presented by in an earlier work by Rauer and colleagues. The main motivation of the present work is to perform a deeper analysis of the chemical processes in the planetary atmospheres. We apply a diagnostic tool, the Pathway Analysis Program, to shed light on the photochemical pathways that form and destroy biosignature species. Ozone is a potential biosignature for complex life. An important result of our analysis is a shift in the ozone photochemistry from mainly Chapman production (which dominates in Earth's stratosphere) to smog-dominated ozone production for planets in the habitable zone of cooler (M5-M7)-class dwarf stars. This result is associated with a lower energy flux in the UVB wavelength range from the central star, hence slower planetary atmospheric photolysis of molecular oxygen, which slows the Chapman ozone production. This is important for future atmospheric characterization missions because it provides an indication of different chemical environments that can lead to very different responses of ozone, for example, cosmic rays. Nitrous oxide, a biosignature for simple bacterial life, is favored for low stratospheric UV conditions, that is, on planets orbiting cooler stars. Transport of this species from its surface source to the stratosphere where it is destroyed can also be a key process. Comparing 1g with 3g scenarios, our analysis suggests it is important to include the effects of interactive chemistry.
Fourier transform spectrometers for remote sensing of planetary atmospheres and surfaces

NASA Astrophysics Data System (ADS)

Shakun, Alexey; Korablev, Oleg; Moshkin, Boris; Grigoriev, Alexey; Ignatiev, Nikolay; Maslov, Igor; Sazonov, Oleg; Patsaev, Dmitry; Kungurov, Andrey; Santos-Skripko, Alexander; Zharkov, Alexander; Stupin, Igor; Merzlyakov, Dmitry; Makarov, Vladislav; Martinovich, Fedor; Nikolskiy, Yuri; Shashkin, Victor

2017-12-01

In planetary research, Fourier transform infrared spectrometers (FTIR) solve a number of important scientific goals related both to the atmosphere and to the surface sounding. For remote orbital measurements, these goals are the thermal sounding of the atmosphere using, in particular, the 15-µm CO2 band, sensitive detections of minor gaseous species and aerosol characterization. FTIR can address similar atmospheric science goals when observing from a planetary surface allowing for better-resolved boundary layer and achieving greater accuracy (longer integration) for minor species detection. For studies of planetary surfaces, characterization of mineralogical composition in a wide IR range including sensitive measurements of hydration of the soil on airless bodies can be done. We outline a family of FTIR instruments dedicated to studies of Mars and the Moon. TIRVIM is a channel of ACS on ExoMars TGO (in orbit around Mars since October 2016). It is a 2-inch interferometer for nadir and solar occultation measurements of Mars' atmosphere. It covers a spectral range of 1.7-17 µm with spectral resolution up to 0.13 cm-1. LUMIS is a similar instrument for Luna-Resource Orbiter (Luna-26) Roscosmos mission dedicated to the search for hydration of the lunar regolith in the 6-µm band. The spectral range of LUMIS is broad (1.7-17 µm), but its sensitivity is optimized for the 4-8 µm region. The spectral resolution is 50 cm-1. We also describe recent developments focused on technical solutions for miniaturized FTIR instruments with a very high spectral resolution (0.05 cm-1 and higher). The prototype targets measurements of minor atmospheric species from the surface of Mars using the Sun tracking. One important task is to provide a high precision of interferometer's mirror movement. Another task is the development of a precise two-coordinate mechanism to seek for and follow the Sun.
Honors

NASA Astrophysics Data System (ADS)

2011-05-01

Among the new members elected to the U.S. National Academy of Sciences in May are five AGU members: Richard Edwards, George and Orpha Gibson Chair of Earth Systems Sciences and Distinguished McKnight University Professor, Department of Geology and Geophysics, University of Minnesota, Minneapolis; T. Mark Harrison, director, Institute of Geophysics and Planetary Physics, and professor of geology, Department of Earth and Space Sciences, University of California, Los Angeles; David Sandwell, professor of geophysics, Institute for Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, La Jolla (president of the AGU Geodesy section); Benjamin Santer, physicist and atmospheric scientist, Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, Calif.; and Steven Wofsy, Abbott Lawrence Rotch Professor of Atmospheric and Environmental Science, Department of Earth and Planetary Sciences, Harvard University, Cambridge, Mass. Four AGU members are among the 2011 prizewinners announced by the Division for Planetary Sciences (DPS) of the American Astronomical Society on 19 May. The prizes will be presented at the joint meeting of DPS and the European Planetary Science Congress in October. William Ward of the Southwest Research Institute, San Antonio, Tex., is the recipient of the Gerard P. Kuiper Prize for outstanding contributions to the field of planetary science. DPS indicated that Ward originally proposed and evaluated “many dynamical processes that are now cornerstones of current theories of how planets form and evolve” and that his “visionary ideas form the foundation for a significant portion of current work in planetary formation and dynamics.”
Applying Multiagent Simulation to Planetary Surface Operations

NASA Technical Reports Server (NTRS)

Sierhuis, Maarten; Sims, Michael H.; Clancey, William J.; Lee, Pascal; Swanson, Keith (Technical Monitor)

2000-01-01

This paper describes a multiagent modeling and simulation approach for designing cooperative systems. Issues addressed include the use of multiagent modeling and simulation for the design of human and robotic operations, as a theory for human/robot cooperation on planetary surface missions. We describe a design process for cooperative systems centered around the Brahms modeling and simulation environment being developed at NASA Ames.
Impact erosion of planetary atmospheres

NASA Astrophysics Data System (ADS)

Shuvalov, Valery

1999-06-01

The problem of planetary atmospheres evolution due to impacts of large cosmic bodies was investigated by Ahrens, O'Keefe, Cameron, Hunten and others. These studies were focused mainly on the atmosphere growth under impact devolatilization and atmosphere losses due to escape of high velocity ejecta. Most of the results concerning atmosphere erosion were based on assumption that atmosphere itself does not influence significantly on the ejecta evolution. However more detailed investigations show that atmospheric drag is important at least for 1-10km impactors. From the other hand the theory of large explosions in an exponential atmosphere is not applicable in the case under consideration because of the influence of a trail created during the body flight through the atmosphere. In the present study the problem of 1-10km asteroid impacts against the Earth is investigated with the use of multi-material hydrocode SOVA. This code is similar to the widely used CTH system and allows to model all stages of the impact (penetration into the atmosphere, collision with the ground surface covered by water basin, ejecta evolution). The air mass ejected from each altitude depending on impactor size and velocity is determined. Apart from the impacts into the present-day atmosphere, the erosion of the dense Proto-Atmosphere is also considered.
Simulation of Venus polar vortices with the non-hydrostatic general circulation model

NASA Astrophysics Data System (ADS)

Rodin, Alexander V.; Mingalev, Oleg; Orlov, Konstantin

2012-07-01

The dynamics of Venus atmosphere in the polar regions presents a challenge for general circulation models. Numerous images and hyperspectral data from Venus Express mission shows that above 60 degrees latitude atmospheric motion is substantially different from that of the tropical and extratropical atmosphere. In particular, extended polar hoods composed presumably of fine haze particles, as well as polar vortices revealing mesoscale wave perturbations with variable zonal wavenumbers, imply the significance of vertical motion in these circulation elements. On these scales, however, hydrostatic balance commonly used in the general circulation models is no longer valid, and vertical forces have to be taken into account to obtain correct wind field. We present the first non-hydrostatic general circulation model of the Venus atmosphere based on the full set of gas dynamics equations. The model uses uniform grid with the resolution of 1.2 degrees in horizontal and 200 m in the vertical direction. Thermal forcing is simulated by means of relaxation approximation with specified thermal profile and time scale. The model takes advantage of hybrid calculations on graphical processors using CUDA technology in order to increase performance. Simulations show that vorticity is concentrated at high latitudes within planetary scale, off-axis vortices, precessing with a period of 30 to 40 days. The scale and position of these vortices coincides with polar hoods observed in the UV images. The regions characterized with high vorticity are surrounded by series of small vortices which may be caused by shear instability of the zonal flow. Vertical velocity component implies that in the central part of high vorticity areas atmospheric flow is downwelling and perturbed by mesoscale waves with zonal wavenumbers 1-4, resembling observed wave structures in the polar vortices. Simulations also show the existence of areas with strong vertical flow, concentrated in spiral branches extending from low latitude to the circumpolar vortex. Qualitatively this pattern suggest that the dynamics of the polar Venus atmosphere resembles that of terrestrial hurricanes, but is characterized with preferentially poleward and downwelling motions.
NASA Planetary Astronomy Lunar Atmospheric Imaging Study

NASA Technical Reports Server (NTRS)

Stern, S. Alan

1996-01-01

Authors have conducted a program of research focused on studies of the lunar atmosphere. Also present preliminary results of an ongoing effort to determine the degree that metal abundances in the lunar atmosphere are stoichiometric, that is, reflective of the lunar surface composition. We make the first-ever mid-ultraviolet spectroscopic search for emission from the lunar atmosphere.
Los Angeles megacity: a high-resolution land–atmosphere modelling system for urban CO 2 emissions

DOE PAGES

Feng, Sha; Lauvaux, Thomas; Newman, Sally; ...

2016-07-22

Megacities are major sources of anthropogenic fossil fuel CO 2 (FFCO 2) emissions. The spatial extents of these large urban systems cover areas of 10 000 km 2 or more with complex topography and changing landscapes. We present a high-resolution land–atmosphere modelling system for urban CO 2 emissions over the Los Angeles (LA) megacity area. The Weather Research and Forecasting (WRF)-Chem model was coupled to a very high-resolution FFCO 2 emission product, Hestia-LA, to simulate atmospheric CO 2 concentrations across the LA megacity at spatial resolutions as fine as ~1 km. We evaluated multiple WRF configurations, selecting one that minimizedmore » errors in wind speed, wind direction, and boundary layer height as evaluated by its performance against meteorological data collected during the CalNex-LA campaign (May–June 2010). Our results show no significant difference between moderate-resolution (4 km) and high-resolution (1.3 km) simulations when evaluated against surface meteorological data, but the high-resolution configurations better resolved planetary boundary layer heights and vertical gradients in the horizontal mean winds. We coupled our WRF configuration with the Vulcan 2.2 (10 km resolution) and Hestia-LA (1.3 km resolution) fossil fuel CO 2 emission products to evaluate the impact of the spatial resolution of the CO 2 emission products and the meteorological transport model on the representation of spatiotemporal variability in simulated atmospheric CO 2 concentrations. We find that high spatial resolution in the fossil fuel CO 2 emissions is more important than in the atmospheric model to capture CO 2 concentration variability across the LA megacity. Finally, we present a novel approach that employs simultaneous correlations of the simulated atmospheric CO 2 fields to qualitatively evaluate the greenhouse gas measurement network over the LA megacity. Spatial correlations in the atmospheric CO 2 fields reflect the coverage of individual measurement sites when a statistically significant number of sites observe emissions from a specific source or location. We conclude that elevated atmospheric CO 2 concentrations over the LA megacity are composed of multiple fine-scale plumes rather than a single homogenous urban dome. Furthermore, we conclude that FFCO 2 emissions monitoring in the LA megacity requires FFCO 2 emissions modelling with ~1 km resolution because coarser-resolution emissions modelling tends to overestimate the observational constraints on the emissions estimates.« less
Los Angeles megacity: a high-resolution land–atmosphere modelling system for urban CO 2 emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Sha; Lauvaux, Thomas; Newman, Sally

Megacities are major sources of anthropogenic fossil fuel CO 2 (FFCO 2) emissions. The spatial extents of these large urban systems cover areas of 10 000 km 2 or more with complex topography and changing landscapes. We present a high-resolution land–atmosphere modelling system for urban CO 2 emissions over the Los Angeles (LA) megacity area. The Weather Research and Forecasting (WRF)-Chem model was coupled to a very high-resolution FFCO 2 emission product, Hestia-LA, to simulate atmospheric CO 2 concentrations across the LA megacity at spatial resolutions as fine as ~1 km. We evaluated multiple WRF configurations, selecting one that minimizedmore » errors in wind speed, wind direction, and boundary layer height as evaluated by its performance against meteorological data collected during the CalNex-LA campaign (May–June 2010). Our results show no significant difference between moderate-resolution (4 km) and high-resolution (1.3 km) simulations when evaluated against surface meteorological data, but the high-resolution configurations better resolved planetary boundary layer heights and vertical gradients in the horizontal mean winds. We coupled our WRF configuration with the Vulcan 2.2 (10 km resolution) and Hestia-LA (1.3 km resolution) fossil fuel CO 2 emission products to evaluate the impact of the spatial resolution of the CO 2 emission products and the meteorological transport model on the representation of spatiotemporal variability in simulated atmospheric CO 2 concentrations. We find that high spatial resolution in the fossil fuel CO 2 emissions is more important than in the atmospheric model to capture CO 2 concentration variability across the LA megacity. Finally, we present a novel approach that employs simultaneous correlations of the simulated atmospheric CO 2 fields to qualitatively evaluate the greenhouse gas measurement network over the LA megacity. Spatial correlations in the atmospheric CO 2 fields reflect the coverage of individual measurement sites when a statistically significant number of sites observe emissions from a specific source or location. We conclude that elevated atmospheric CO 2 concentrations over the LA megacity are composed of multiple fine-scale plumes rather than a single homogenous urban dome. Furthermore, we conclude that FFCO 2 emissions monitoring in the LA megacity requires FFCO 2 emissions modelling with ~1 km resolution because coarser-resolution emissions modelling tends to overestimate the observational constraints on the emissions estimates.« less
A bibliography of planetary geology principal investigators and their associates, 1982 - 1983

NASA Technical Reports Server (NTRS)

Plescia, J. B.

1984-01-01

This bibliography cites recent publications by principal investigators and their associates, supported through NASA's Office of Space Science and Applications, Earth and Planetary Exploration Division, Planetary Geology Program. It serves as a companion piece to NASA TM-85127, ""Reports of Planetary Programs, 1982". Entries are listed under the following subject areas: solar system, comets, asteroids, meteorites and small bodies; geologic mapping, geomorphology, and stratigraphy; structure, tectonics, and planetary and satellite evolutions; impact craters; volcanism; fluvial, mass wasting, glacial and preglacial studies; Eolian and Arid climate studies; regolith, volatiles, atmosphere, and climate, radar; remote sensing and photometric studies; and cartography, photogrammetry, geodesy, and altimetry. An author index is provided.

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