The "Horns" of FK Comae and the Complex Structure of its Outer Atmosphere

NASA Astrophysics Data System (ADS)

Saar, Steven H.; Ayres, T. R.; Kashyap, V.

2014-01-01

As part of a large multiwavelength campaign (COCOA-PUFS*) to explore magnetic activity in the unusual, single, rapidly rotating giant FK Comae, we have taken a time series of moderate resolution FUV spectra of the star with the COS spectrograph on HST. We find that the star has unusual, time-variable emission profiles in the chromosphere and transition region which show horn-like features. We use simple spatially inhomogeneous models to explain the variable line shapes. Modeling the lower chromospheric Cl I 1351 Å line, we find evidence for a very extended, spatial inhomogeneous outer atmosphere, likely composed of many huge "sling-shot" prominences of cooler material with embedded in a rotationally distended corona. We compare these results with hotter hotter transition region lines (Si IV) and optical spectra of the chromospheric He I D3 line. We also employ the model Cl I profiles, and data-derived empirical models, to fit the complex spectral region around the coronal Fe XXI 1354.1 Å line. We place limits on the flux of this line, and show these limits are consistent with expectations from the observed X-ray spectrum. *Campaign for Observation of the Corona and Outer Atmosphere of the Fast-rotating Star, FK Comae This work was supported by HST grant GO-12376.01-A.

An Integrated Modeling Study for Coordinated Observations of H, O, OH, and H2O(+) Emissions in the Coma and Ion Tail of the Comet Hale-Bopp

NASA Technical Reports Server (NTRS)

Smyth, William H.

2001-01-01

This project has two overall objectives. One objective is to advance our general understanding of both the comet neutral atmosphere and the cometary plasma in the atmosphere and ion tall. The other objective is to obtain specific key information about comet Hale-Bopp that is generally important for Hale-Bopp studies. The primary emphasis in this project is to analyze, in a self-consistent manner, excellent quality high resolution image and line profile observations obtained by the University of Wisconsin for H, O, OH, and H2O+ emissions from the inner coma, outer coma, and ion tail of Hale-Bopp. The information on the spatial and velocity distributions of H2O neutral and ionized photo-products in the inner coma, outer coma, and in the H2O+ ion tail is of substantial and direct importance in the development of an integrated understanding of the complex structure and dynamics of the neutral and plasma species in the atmosphere of Hale-Bopp in particular and comets in general. The H2O production rate of Hale-Bopp is determined and, together with the other information related to the structure and dynamics of the neutral and plasma atmospheres obtained in this study, provide critical information important for a wide variety of research conducted by other groups.

Comparative atmosphere structure experiment

NASA Technical Reports Server (NTRS)

Sommer, S.

1974-01-01

Atmospheric structure of outer planets as determined by pressure, temperature, and accelerometers is reviewed and results obtained from the PAET earth entry are given. In order to describe atmospheric structure, entry is divided into two regimes, high and low speed. Acceleration is then measured: from these measurements density is determined as a function of time. The equations of motion are integrated to determine velocity, flight path angle, and altitude as a function of time. Density is then determined as a function of altitude from the previous determinations of density and altitude as a function of time. Hydrostatic equilibrium was assumed to determine pressure as a function of altitude. Finally the equation of space applied to determine temperature as a function of altitude, if the mean molecular weight is known. The mean molecular weight is obtained independently from either the low speed experiment or from the composition experiments.

Sodars and their application for investigation of the turbulent structure of the lower atmosphere

NASA Astrophysics Data System (ADS)

Krasnenko, N. P.; Shamanaeva, L. G.

2016-11-01

Possibilities of sodar application for investigation of the spatiotemporal dynamics of three components of wind velocity vector, longitudinal and transverse structural functions of wind velocity field, structural characteristics of temperature and wind velocity, turbulent kinetic energy dissipation rate, and outer scales of temperature and dynamic turbulence in the atmospheric boundary layer are analyzed. The original closed iterative algorithm of sodar data processing taking into account the classical and molecular absorption and the turbulent sound attenuation on the propagation path is used that allows the vertical profiles of the characteristics of temperature and wind velocity field to be reconstructed simultaneously and their interrelations to be investigated. It is demonstrated how the structure of temperature and wind turbulence is visualised in real time.

Stellar Occultation Studies of Pluto, Triton, Charon, and Chiron

NASA Technical Reports Server (NTRS)

Elliot, James L.

2002-01-01

Bodies inhabiting the outer solar system are of interest because, due to the colder conditions, they exhibit unique physical processes. Also, some of the lessons learned from them can be applied to understanding what occurred in the outer solar system during its formation and early evolution. The thin atmospheres of Pluto and Triton have structure that is not yet understood, and they have been predicted to undergo cataclysmic seasonal changes. Charon may have an atmosphere - we don't know. Chiron exhibits cometary activity so far from the sun (much further than most comets), so that H2O sublimation cannot be the driving mechanism. Probing these bodies from Earth with a spatial resolution of a few kilometers can be accomplished only with the stellar occultation technique. In this program we find and predict stellar occultation events by small outer-solar system bodies and then attempt observations of the ones that can potentially answer interesting questions. We also develop new methods of data analysis for occultations and secure other observations that are necessary for interpretation of the occultation data.

The Giant Planet Satellite Exospheres

NASA Technical Reports Server (NTRS)

McGrath, Melissa A.

2014-01-01

Exospheres are relatively common in the outer solar system among the moons of the gas giant planets. They span the range from very tenuous, surface-bounded exospheres (e.g., Rhea, Dione) to quite robust exospheres with exobase above the surface (e.g., lo, Triton), and include many intermediate cases (e.g., Europa, Ganymede, Enceladus). The exospheres of these moons exhibit an interesting variety of sources, from surface sputtering, to frost sublimation, to active plumes, and also well illustrate another common characteristic of the outer planet satellite exospheres, namely, that the primary species often exists both as a gas in atmosphere, and a condensate (frost or ice) on the surface. As described by Yelle et al. (1995) for Triton, "The interchange of matter between gas and solid phases on these bodies has profound effects on the physical state of the surface and the structure of the atmosphere." A brief overview of the exospheres of the outer planet satellites will be presented, including an inter-comparison of these satellites exospheres with each other, and with the exospheres of the Moon and Mercury.

Magnetic tornadoes as energy channels into the solar corona.

PubMed

Wedemeyer-Böhm, Sven; Scullion, Eamon; Steiner, Oskar; van der Voort, Luc Rouppe; de la Cruz Rodriguez, Jaime; Fedun, Viktor; Erdélyi, Robert

2012-06-27

Heating the outer layers of the magnetically quiet solar atmosphere to more than one million kelvin and accelerating the solar wind requires an energy flux of approximately 100 to 300 watts per square metre, but how this energy is transferred and dissipated there is a puzzle and several alternative solutions have been proposed. Braiding and twisting of magnetic field structures, which is caused by the convective flows at the solar surface, was suggested as an efficient mechanism for atmospheric heating. Convectively driven vortex flows that harbour magnetic fields are observed to be abundant in the photosphere (the visible surface of the Sun). Recently, corresponding swirling motions have been discovered in the chromosphere, the atmospheric layer sandwiched between the photosphere and the corona. Here we report the imprints of these chromospheric swirls in the transition region and low corona, and identify them as observational signatures of rapidly rotating magnetic structures. These ubiquitous structures, which resemble super-tornadoes under solar conditions, reach from the convection zone into the upper solar atmosphere and provide an alternative mechanism for channelling energy from the lower into the upper solar atmosphere.

Planetary/DOD entry technology flight experiments. Volume 2: Planetary entry flight experiments

NASA Technical Reports Server (NTRS)

Christensen, H. E.; Krieger, R. J.; Mcneilly, W. R.; Vetter, H. C.

1976-01-01

The technical feasibility of launching a high speed, earth entry vehicle from the space shuttle to advance technology for the exploration of the outer planets' atmospheres was established. Disciplines of thermodynamics, orbital mechanics, aerodynamics propulsion, structures, design, electronics and system integration focused on the goal of producing outer planet environments on a probe shaped vehicle during an earth entry. Major aspects of analysis and vehicle design studied include: planetary environments, earth entry environment capability, mission maneuvers, capabilities of shuttle upper stages, a comparison of earth entry planetary environments, experiment design and vehicle design.

Atmospheric Mining in the Outer Solar System: Resource Capturing, Storage, and Utilization

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2014-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as helium 3 and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate for hydrogen helium 4 and helium 3, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues.

Definition and empirical structure of the range of stellar chromospheres-coronae across the H-R diagram: Cool stars

NASA Technical Reports Server (NTRS)

Linsky, J. L.

1986-01-01

Major advances in our understanding of non-radiative heating and other activity in stars cooler than T sub eff = 10,000K has occured in the last few years. This observational evidence is reviewed and the trends that are now becoming apparent are discussed. The evidence for non-radiatively heated outer atmospheric layers (chromospheres, transition regions, and coronae) in dwarf stars cooler than spectral type A7, in F and G giants, pre-main sequence stars, and close bindary systems is unambiguous, as is the evidence for chromospheres in the K and M giants and supergiants. The existence of non-radiative heating in the outer layers of the A stars remains undetermined despite repeated searches at all wavelengths. Two important trends in the data are the decrease in plasma emission measure with age on the main sequence and decreasing rotational velocity. Variability and atmospheric inhomogeneity are commonly seen, and there is considerable evidence that magnetic fields define the geometry and control the energy balance in the outer atmospheric layers. In addition, the microwave observations imply that non-thermal electrons are confined in coronal magnetic flux tubes in at least the cool dwarfs and RS CVn systems. The chromospheres in the K and M giants and supergiants are geometrically extended, as are the coronae in the RS CVn systems and probably also in other stars.

Three-dimensional structure of wind turbine wakes as measured by scanning lidar

NASA Astrophysics Data System (ADS)

Bodini, Nicola; Zardi, Dino; Lundquist, Julie K.

2017-08-01

The lower wind speeds and increased turbulence that are characteristic of turbine wakes have considerable consequences on large wind farms: turbines located downwind generate less power and experience increased turbulent loads. The structures of wakes and their downwind impacts are sensitive to wind speed and atmospheric variability. Wake characterization can provide important insights for turbine layout optimization in view of decreasing the cost of wind energy. The CWEX-13 field campaign, which took place between June and September 2013 in a wind farm in Iowa, was designed to explore the interaction of multiple wakes in a range of atmospheric stability conditions. Based on lidar wind measurements, we extend, present, and apply a quantitative algorithm to assess wake parameters such as the velocity deficits, the size of the wake boundaries, and the location of the wake centerlines. We focus on wakes from a row of four turbines at the leading edge of the wind farm to explore variations between wakes from the edge of the row (outer wakes) and those from turbines in the center of the row (inner wakes). Using multiple horizontal scans at different elevations, a three-dimensional structure of wakes from the row of turbines can be created. Wakes erode very quickly during unstable conditions and can in fact be detected primarily in stable conditions in the conditions measured here. During stable conditions, important differences emerge between the wakes of inner turbines and the wakes of outer turbines. Further, the strong wind veer associated with stable conditions results in a stretching of the wake structures, and this stretching manifests differently for inner and outer wakes. These insights can be incorporated into low-order wake models for wind farm layout optimization or for wind power forecasting.

Three-dimensional structure of wind turbine wakes as measured by scanning lidar

DOE PAGES

Bodini, Nicola; Zardi, Dino; Lundquist, Julie K.

2017-08-14

The lower wind speeds and increased turbulence that are characteristic of turbine wakes have considerable consequences on large wind farms: turbines located downwind generate less power and experience increased turbulent loads. The structures of wakes and their downwind impacts are sensitive to wind speed and atmospheric variability. Wake characterization can provide important insights for turbine layout optimization in view of decreasing the cost of wind energy. The CWEX-13 field campaign, which took place between June and September 2013 in a wind farm in Iowa, was designed to explore the interaction of multiple wakes in a range of atmospheric stability conditions.more » Based on lidar wind measurements, we extend, present, and apply a quantitative algorithm to assess wake parameters such as the velocity deficits, the size of the wake boundaries, and the location of the wake centerlines. We focus on wakes from a row of four turbines at the leading edge of the wind farm to explore variations between wakes from the edge of the row (outer wakes) and those from turbines in the center of the row (inner wakes). Using multiple horizontal scans at different elevations, a three-dimensional structure of wakes from the row of turbines can be created. Wakes erode very quickly during unstable conditions and can in fact be detected primarily in stable conditions in the conditions measured here. During stable conditions, important differences emerge between the wakes of inner turbines and the wakes of outer turbines. Further, the strong wind veer associated with stable conditions results in a stretching of the wake structures, and this stretching manifests differently for inner and outer wakes. As a result, these insights can be incorporated into low-order wake models for wind farm layout optimization or for wind power forecasting.« less

Three-dimensional structure of wind turbine wakes as measured by scanning lidar

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

Bodini, Nicola; Zardi, Dino; Lundquist, Julie K.

The lower wind speeds and increased turbulence that are characteristic of turbine wakes have considerable consequences on large wind farms: turbines located downwind generate less power and experience increased turbulent loads. The structures of wakes and their downwind impacts are sensitive to wind speed and atmospheric variability. Wake characterization can provide important insights for turbine layout optimization in view of decreasing the cost of wind energy. The CWEX-13 field campaign, which took place between June and September 2013 in a wind farm in Iowa, was designed to explore the interaction of multiple wakes in a range of atmospheric stability conditions.more » Based on lidar wind measurements, we extend, present, and apply a quantitative algorithm to assess wake parameters such as the velocity deficits, the size of the wake boundaries, and the location of the wake centerlines. We focus on wakes from a row of four turbines at the leading edge of the wind farm to explore variations between wakes from the edge of the row (outer wakes) and those from turbines in the center of the row (inner wakes). Using multiple horizontal scans at different elevations, a three-dimensional structure of wakes from the row of turbines can be created. Wakes erode very quickly during unstable conditions and can in fact be detected primarily in stable conditions in the conditions measured here. During stable conditions, important differences emerge between the wakes of inner turbines and the wakes of outer turbines. Further, the strong wind veer associated with stable conditions results in a stretching of the wake structures, and this stretching manifests differently for inner and outer wakes. As a result, these insights can be incorporated into low-order wake models for wind farm layout optimization or for wind power forecasting.« less

Outer atmospheres of giant and supergiant stars

NASA Technical Reports Server (NTRS)

Brown, A.

1984-01-01

The properties of the chromospheres, transition regions and coronas of cool evolved stars are reviewed based primarily on recent ultraviolet and X-ray studies. Determinations of mass loss rates using new observational techniques in the ultraviolet and radio spectral regions are discussed and observations indicating general atmospheric motions are considered. The techniques available for the quantitative modeling of these atmospheres are outlined and recent results discussed. Finally, the current rudimentary understanding of the evolution of these outer atmospheres and its causes are considered.

Review of the outer scale of the atmospheric turbulence

NASA Astrophysics Data System (ADS)

Ziad, Aziz

2016-07-01

Outer scale is a relevant parameter for the experimental performance evaluation of large telescopes. Different techniques have been used for the outer scale estimation. In situ measurements with radiosounding balloons have given very small values of outer scale. This latter has also been estimated directly at the ground level from the wavefront analysis with High Angular Resolution (HAR) techniques using interferometric or Shack-Hartmann or more generally AO systems data. Dedicated instruments have been also developed for the outer scale monitoring such as the Generalized Seeing Monitor (GSM) and the Monitor of Outer Scale Profile (MOSP). The measured values of outer scale from HAR techniques, GSM and MOSP are somewhat coherent and are larger than the in situ results. The main explanation of this difference comes from the definition of the outer scale itself. This paper aims to give a review in a non-exhaustive way of different techniques and instruments for the measurement of the outer scale. Comparisons of outer scale measurements will be discussed in the light of the different definitions of this parameter, the associated observable quantities and the atmospheric turbulence model as well.

Atmospheric Mining in the Outer Solar System: Resource Capturing, Storage, and Utilization

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2012-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate for hydrogen helium 4 and helium 3, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues.

Atmospheric Mining in the Outer Solar System: Aerial Vehicle Mission and Design Issues

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2015-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists. The mining aerospacecraft (ASC) could fly through the outer planet atmospheres, for global weather observations, localized storm or other disturbance investigations, wind speed measurements, polar observations, etc. Analyses of orbital transfer vehicles (OTVs), landers, and in-situ resource utilization (ISRU) mining factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points.

On the outer scale of turbulence in the atmospheric surface layer

NASA Astrophysics Data System (ADS)

de Bruin, H. A. R.; Beyrich, F.

2009-09-01

The well-known Kolmogorov and Tatarskii similarity relations for spectra in the atmospheric surface layer are derived for an eddy-size region between the outer and inner scale (L0 and l0 respectively). Remarkably few studies are devoted to the outer scale L0. Tatarski (1992) defined it through the ratio of twice the variance and the structure parameter of temperature to the power 3/2. In most studies L0 is assumed to be proportional to the height z (Wheelon, 2001, pag. 79). In our study we will introduce an alternative definition for L0.. Next, its behavior will be investigated analyzing different data sets gathered under a wide range of conditions and observations height. During daytime, L0 appears to vary with z indeed, but with lot of scatter and systematic differences. The consequences of these findings for different remote sensing techniques such a scintillometry will be discussed. Tatarskii, V.I., 1992: Review of scintillation phenomena, in: Tatarskii et al. (Eds.): Wave Propagation in Random Media (Scintillation), Spie Press, 2-16. Wheelon, A.D., 2001: Electromagnetic Scintillation, part I Geometrical Optics, Cambridge University Press, 455 pp

Investigation of feasibility of wind turbulence measurement by a pulsed coherent doppler lidar in the atmospheric boundary layer

NASA Astrophysics Data System (ADS)

Smalikho, Igor; Banakh, Viktor

2018-04-01

Feasibilities of determination of the wind turbulence parameters from data measured by the Stream Line coherent Doppler lidar under different atmospheric conditions have been studied experimentally. It has been found that the spatial structure of the turbulence is described well by the von Karman model in the layer of intensive mixing. From the lidar measurements at night under stable conditions the estimation of the outer scale of turbulence with the use of the von Karman model is not possible.

A simple approach for estimating the refractive index structure parameter (Cn²) profile in the atmosphere.

PubMed

Basu, Sukanta

2015-09-01

Utilizing the so-called Thorpe scale as a measure of the turbulence outer scale, we propose a physically-based approach for the estimation of Cn2 profiles in the lower atmosphere. This approach only requires coarse-resolution temperature profiles (a.k.a., soundings) as input, yet it has the intrinsic ability to capture layers of high optical turbulence. The prowess of this computationally inexpensive approach is demonstrated by validations against observational data from a field campaign over Mauna Kea, Hawaii.

ATLAS-SOHO: Satellite Arrival and Uncrating, Uncrating of the Propulsion Unit and Electric Module

NASA Technical Reports Server (NTRS)

1995-01-01

The SOHO satellite, part of the International Solar-Terrestrial Physics Program (ISTP), is a solar observatory designed to study the structure, chemical composition, and dynamics of the solar interior. It will also observe the structure (density, temperature and velocity fields), dynamics and composition of the outer solar atmosphere, and the solar wind and its relation to the solar atmosphere. The spacecraft was launched on December 2, 1995. This video shows the unloading of the satellite from the transport plane at the Kennedy Space Station and the lowering to an awaiting flatbed truck. The video also shows the uncrating of the satellite, the propulsion unit and the electric module in a clean room.

High-voltage electrical apparatus utilizing an insulating gas of sulfur hexafluoride and helium

DOEpatents

Wootton, Roy E.

1980-01-01

High-voltage electrical apparatus includes an outer housing at low potential, an inner electrode disposed within the outer housing at high potential with respect thereto, and support means for insulatably supporting the inner electrode within the outer housing. Conducting particles contaminate the interior of the outer housing, and an insulating gas electrically insulates the inner electrode from the outer housing even in the presence of the conducting particles. The insulating gas is comprised of sulfur hexafluoride at a partial pressure of from about 2.9 to about 3.4 atmospheres absolute, and helium at a partial pressure from about 1.1 to about 11.4 atmospheres absolute. The sulfur hexafluoride comprises between 20 and 65 volume percent of the insulating gas.

Atmospheric turbulence chamber for optical transmission experiment Characterization by thermal method

NASA Technical Reports Server (NTRS)

Gamo, H.; Majumdar, A. K.

1978-01-01

Consideration is given to an atmospheric turbulence chamber designed for optical wave propagation experiments. The chamber consists of ten small electric heater/blowers with an aluminum foil screen and three screens of 2-mm aluminum wire meshes. Calculations are made of the temperature structure constant squared on the basis of temperature structure function measurements derived from a differential microthermocouple system. Values are presented for the refractive-index structure constant squared. The average wind velocity and temperature are found to be, respectively, 0.41 m/sec and 53 C. The inner and outer scales of turbulence are 5.0 mm and 6.5 cm. It is shown that the measured temperature structure function and the power spectrum of temperature fluctuations satisfy, respectively, the 2/3 and -5/3 power similarity laws in the inertial subrange. Possible chamber improvements are discussed.

Method and system for control of upstream flowfields of vehicle in supersonic or hypersonic atmospheric flight

NASA Technical Reports Server (NTRS)

Daso, Endwell O. (Inventor); Pritchett, II, Victor E. (Inventor); Wang, Ten-See (Inventor); Farr, Rebecca Ann (Inventor)

2012-01-01

The upstream flowfield of a vehicle traveling in supersonic or hypersonic atmospheric flight is actively controlled using attribute(s) experienced by the vehicle. Sensed attribute(s) include pressure along the vehicle's outer mold line, temperature along the vehicle's outer mold line, heat flux along the vehicle's outer mold line, and/or local acceleration response of the vehicle. A non-heated, non-plasma-producing gas is injected into an upstream flowfield of the vehicle from at least one surface location along the vehicle's outer mold line. The pressure of the gas so-injected is adjusted based on the attribute(s) so-sensed.

Wigner distribution function and kurtosis parameter of vortex beams propagating through turbulent atmosphere

NASA Astrophysics Data System (ADS)

Suo, Qiangbo; Han, Yiping; Cui, Zhiwei

2017-09-01

Based on the extended Huygens-Fresnel integral, the analytical expressions for the Wigner distribution function (WDF) and kurtosis parameter of partially coherent flat-topped vortex (PCFTV) beams propagating through atmospheric turbulence and free space are derived. The WDF and kurtosis parameter of PCFTV beams through turbulent atmosphere are discussed with numerical examples. The numerical results show that the beam quality depends on the structure constants, the inner scale turbulence, the outer scale turbulence, the spatial correlation length, the wave length and the beam order. PCFTV beams are less affected by turbulence than partially flat-topped coherent (PCFT) beams under the same conditions, and will be useful in free-space optical communications.

The thermodynamic evolution of the hurricane boundary layer during eyewall replacement cycles

NASA Astrophysics Data System (ADS)

Williams, Gabriel J.

2017-12-01

Eyewall replacement cycles (ERCs) are frequently observed during the lifecycle of mature tropical cyclones. Although the kinematic structure and intensity changes during an ERC have been well-documented, comparatively little research has been done to examine the evolution of the tropical cyclone boundary layer (TCBL) during an ERC. This study will examine how the inner core thermal structure of the TCBL is affected by the presence of multiple concentric eyewalls using a high-resolution moist, hydrostatic, multilayer diagnostic boundary layer model. Within the concentric eyewalls above the cloud base, latent heat release and vertical advection (due to the eyewall updrafts) dominate the heat and moisture budgets, whereas vertical advection (due to subsidence) and vertical diffusion dominate the heat and moisture budgets for the moat region. Furthermore, it is shown that the development of a moat region within the TCBL depends sensitively on the moat width in the overlying atmosphere and the relative strength of the gradient wind field in the overlying atmosphere. These results further indicate that the TCBL contributes to outer eyewall formation through a positive feedback process between the vorticity in the nascent outer eyewall, boundary layer convergence, and boundary layer moist convection.

Evolution of Initial Atmospheric Corrosion of Carbon Steel in an Industrial Atmosphere

NASA Astrophysics Data System (ADS)

Pan, Chen; Han, Wei; Wang, Zhenyao; Wang, Chuan; Yu, Guocai

2016-12-01

The evolution of initial corrosion of carbon steel exposed to an industrial atmosphere in Shenyang, China, has been investigated by gravimetric, XRD, SEM/EDS and electrochemical techniques. The kinetics of the corrosion process including the acceleration and deceleration processes followed the empirical equation D = At n . The rust formed on the steel surface was bi-layered, comprised of an inner and outer layer. The outer layer was formed within the first 245 days and had lower iron content compared to the inner layer. However, the outer layer disappeared after 307 days of exposure, which is considered to be associated with the depletion of Fe3O4. The evolution of the rust layer formed on the carbon steel has also been discussed.

Radiative Transfer Analysis of Neptune’s New Dark Vortex

NASA Astrophysics Data System (ADS)

Tollefson, Joshua; Luszcz-Cook, Statia H.; Wong, Michael H.; de Pater, Imke

2017-10-01

A new dark spot on Neptune was discovered in late 2015, named: "SDS-2015" for "Southern Dark Spot discovered in 2015". Subsequent observations from Hubble Space Telescope Mid-Cycle 23 (PI: Wong) and the Outer Planetary Atmospheres Legacy (OPAL) programs (PI: Simon-Miller) took the first multispectral data over multiple viewing geometries of a Neptunian dark spot, spanning wavelengths from 336 to 763nm. SDS-2015 is visible at blue wavelengths, with contrast from the background atmosphere peaking at 467nm. In this abstract, we present a radiative transfer analysis of the dark spot and surrounding background atmosphere. We summarize our retrieved properties of Neptune's background atmosphere, including its aerosol structure and methane profile, and compare our findings in the optical wavelengths to those in the near-infrared. We then discuss various hypotheses about the make up of SDS-2015 and its interaction with the background atmosphere.

Effects of turbulence in the atmosphere of Venus on Pioneer Venus radio, phase 1

NASA Technical Reports Server (NTRS)

Woo, R.; Kendall, W.; Ishimaru, A.; Berwin, R.

1973-01-01

The prediction of the turbulence effects in the Venus atmosphere on Pioneer Venus radio was investigated. A careful investigation based on a theoretical and experimental study of the power spectrum of the Mariner 5 amplitude fluctuations is carried out and the results contribute considerably to our scientific knowledge of turbulence in the atmosphere of Venus. Fully developed turbulence is seen to exist predominantly in the altitude range of 41 - 49 km. This result is consistent with the high wind shear and wind velocities observed by Venera 4 for altitudes higher than 40 km. The outer scale size of turbulence is on the order of 100 m, the structure constant for the dayside atmosphere 3.9 x 10 to the -7 power m to the -1/3rd power, and that for the nightside atmosphere 2.9 x 10 to the -7 power m to the -1/3rd power.

A Volcanic Hydrogen Habitable Zone

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

Ramirez, Ramses M.; Kaltenegger, Lisa, E-mail: rmr277@cornell.edu

The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N{sub 2}–CO{sub 2}–H{sub 2}O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO{sub 2} outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H{sub 2} can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N{sub 2}–CO{sub 2}–H{sub 2}O–H{sub 2}) can be sustained as long as volcanic H{submore » 2} output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H{sub 2} warming is reduced in dense H{sub 2}O atmospheres. The atmospheric scale heights of such volcanic H{sub 2} atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.« less

Self sterilization of bodies during outer planet entry. [atmospheric temperature effects

NASA Technical Reports Server (NTRS)

Hoffman, A. R.; Jaworski, W.; Taylor, D. M.

1975-01-01

As a body encounters the atmosphere of an outer planet, whether accidentally or by plan, it will be subjected to heat loads which could result in high temperature conditions that render terrestrial organisms on or within the body non-viable. To determine whether an irregularly shaped entering body, consisting of several different materials, would be sterilized during inadvertent entry at high velocity, the thermal response of a typical outer planet spacecraft instrument was studied. The results indicate that the Teflon-insulated cable and electronic circuit boards may not experience sterilizing temperatures during a Jupiter, Saturn, or Titan entry. Another conclusion of the study is that small plastic particles entering Saturn from outer space have wider survival corridors than do those at Jupiter.

Jupiter's evolution with primordial composition gradients

NASA Astrophysics Data System (ADS)

Vazan, Allona; Helled, Ravit; Guillot, Tristan

2018-02-01

Recent formation and structure models of Jupiter suggest that the planet can have composition gradients and not be fully convective (adiabatic). This possibility directly affects our understanding of Jupiter's bulk composition and origin. In this Letter we present Jupiter's evolution with a primordial structure consisting of a relatively steep heavy-element gradient of 40 M⊕. We show that for a primordial structure with composition gradients, most of the mixing occurs in the outer part of the gradient during the early evolution (several 107 yr), leading to an adiabatic outer envelope (60% of Jupiter's mass). We find that the composition gradient in the deep interior persists, suggesting that 40% of Jupiter's mass can be non-adiabatic with a higher temperature than the one derived from Jupiter's atmospheric properties. The region that can potentially develop layered convection in Jupiter today is estimated to be limited to 10% of the mass. Movies associated to Figs. 1-3 are available at http://https://www.aanda.org

Fine Structure of Plasmaspheric Hiss

NASA Astrophysics Data System (ADS)

Summers, D.; Omura, Y.; Nakamura, S.; Kletzing, C.

2014-12-01

Plasmaspheric hiss plays a key role in controlling the structure and dynamics of Earth's radiation belts.The quiet time slot region between the inner and outer belts can be explained as a steady-state balance between earthward radial diffusion and pitch-angle scattering loss of energetic electrons to the atmosphere induced by plasmaspheric hiss. Plasmaspheric hiss can also induce gradual precipitation loss of MeV electrons from the outer radiation belt. Plasmaspheric hiss has been widely regarded as a broadband,structureless,incoherent emission. Here, by examining burst-mode vector waveform data from the EMFISIS instrument on the Van Allen Probes mission,we show that plasmaspheric hiss is a coherent emission with complex fine structure. Specifically, plasmaspheric hiss appears as discrete rising tone and falling tone elements. By means of waveform analysis we identify typical amplitudes,phase profiles,and sweep rates of the rising and falling tone elements. The new observations reported here can be expected to fuel a re-examination of the properties of plasmaspheric hiss, including a further re-analysis of the generation mechanism for hiss.

Performance analysis of a Hartmann wavefront sensor used for sensing atmospheric turbulence statistics

NASA Astrophysics Data System (ADS)

Welsh, Byron M.; Reeves, Toby D.; Roggemann, Michael C.

1997-09-01

The ability to measure atmospheric turbulence characteristics such as Fried's coherence diameter, the outer scale of turbulence, and the turbulence power law are critical for the optimized operation of adaptive optical telescopes. One approach for sensing these turbulence parameters is to use a Hartmann wavefront sensor (H-WFS) array to measure the wavefront slope structure function (SSF) . The SSF is defined as the second moment of the wavefront slope difference between any two subapertures separated in time and/or space. Accurate knowledge of the SSF allows turbulence parameters to be estimated. The H-WFS slope measurements, composed of a true slope signal corrupted by noise, are used to estimate the SSF by computing a mean square difference of slope signals from different subapertures. This computation is typically performed over a large number of H-WFS measurement frames. The quality of the SSF estimate is quantified by the signal-to-noise ratio (SNR) of the estimator. The quality of the SSF estimate then can in turn be related to the quality of the atmospheric turbulence parameter estimates. This research develops a theoretical SNR expression for the SSF estimator. This SNR is a function of H-WFS geometry, the number of temporal measurement frames, the outer scale of turbulence, the turbulence spectrum power law, and the temporal properties of the turbulence. Results are presented for various H-WFS configurations and atmospheric turbulence properties.

Atmospheric Mining in the Outer Solar System: Outer Planet In-Space Bases and Moon Bases for Resource Processing

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2017-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. The propulsion and transportation requirements for all of the major moons of Uranus and Neptune are presented. Analyses of orbital transfer vehicles (OTVs), landers, factories, and the issues with in-situ resource utilization (ISRU) low gravity processing factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points. Several artificial gravity in-space base designs and orbital sites at Uranus and Neptune and the OTV requirements to support them are also addressed.

Test evaluation of potential heatshield contamination of an outer planet probe's gas sampling system

NASA Technical Reports Server (NTRS)

Kessler, W. C.

1975-01-01

The feasibility of retaining the heat shield for outer planet probes was investigated as a potential source of atmospheric sample contamination by outgassing. The onboard instruments which are affected by the concept are the pressure sensor, temperature sensor, IR detector, nephelometer, and gas sampling instruments. It was found that: (1) The retention of the charred heatshield and the baseline atmospheric sampling concepts are compatible with obtaining noncontaminated atmospheric samples. (2) Increasing the sampling tube length so that it extends beyond the viscous boundary layer eliminates contamination of the atmospheric sample. (3) The potential for contamination increases with angle of attack.

Ten bar probe technical summary. [feasibility of outer planet common atmospheric probe

NASA Technical Reports Server (NTRS)

Ellis, T. R.

1974-01-01

The feasibility of an outer planet common atmospheric probe is studied with emphasis on entry heating rates and improved ephemeris. It is concluded that a common probe design is possible except for Jupiter; the basic technology exists except for Jupiter heat shielding. A Mariner class bus provides for better bus science and probe bus communications than a Pioneer class bus.

Hydrogen dimer structures in the far-infrared spectra of Jupiter and Saturn

NASA Technical Reports Server (NTRS)

Frommhold, L.; Samuelson, R.; Birnbaum, G.

1984-01-01

On the basis of a spectral line shape computation and radiative transfer calculations, it is shown that the unexplained, diminutive structures seen in the Voyager IRIS Jovian spectra near the hydrogen S0(0) and S0(1) rotational frequencies are due to bound-free transitions involving hydrogen dimers. The absorption intensities of these transitions, as well as of the collision-induced background, are given. These dimer structures may possibly prove to be useful for determining the helium/hydrogen ratio and the para-hydrogen fraction in the atmospheres of the outer planets.

Clearing the Air: New Approaches to Life Support in Outer Space

NASA Technical Reports Server (NTRS)

Knox, J.; Howard, D.

2008-01-01

This article reports on research into atmospheric revitalization systems for long-term space travel and the use ofCOMSOL Multiphysics to understand how structured sorbents can be used to improve the performance of adsorption processes via thermal management. We are developing the next generation of atmosphere revitalization systems, which will reach for new levels of resource conservation via a high percentage of loop closure. For example, a high percentage of carbon dioxide, exhaled by crew, can be converted via reaction to drinking water, closing the loop from human metabolic waste to supply. Adsorption processes play a lead role in these new/closed loop systems.

Method and System for Weakening Shock Wave Strength at Leading Edge Surfaces of Vehicle in Supersonic Atmospheric Flight

NASA Technical Reports Server (NTRS)

Pritchett, Victor E., II (Inventor); Wang, Ten-See (Inventor); Blankson, Isaiah M. (Inventor); Daso, Endwell O. (Inventor); Farr, Rebecca Ann (Inventor); Auslender, Aaron Howard (Inventor); Plotkin, Kenneth J. (Inventor)

2015-01-01

A method and system are provided to weaken shock wave strength at leading edge surfaces of a vehicle in atmospheric flight. One or more flight-related attribute sensed along a vehicle's outer mold line are used to control the injection of a non-heated, non-plasma-producing gas into a local external flowfield of the vehicle from at least one leading-edge surface location along the vehicle's outer mold line. Pressure and/or mass flow rate of the gas so-injected is adjusted in order to cause a Rankine-Hugoniot Jump Condition along the vehicle's outer mold line to be violated.

GHRS Observations of Cool, Low-Gravity Stars. 5; The Outer Atmosphere and Wind of the Nearby K Supergiant Lambda Velorum

NASA Technical Reports Server (NTRS)

Carpenter, Kenneth G.; Robinson, Richard D.; Harper, Graham M.; Bennett, Philip D.; Brown, Alexander; Mullan, Dermott J.

1999-01-01

UV spectra of lambda Velorum taken with the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope are used to probe the structure of the outer atmospheric layers and wind and to estimate the mass-loss rate from this K5 lb-II supergiant. VLA radio observations at lambda = 3.6 cm are used to obtain an independent check on the wind velocity and mass-loss rate inferred from the UV observations, Parameters of the chromospheric structure are estimated from measurements of UV line widths, positions, and fluxes and from the UV continuum flux distribution. The ratios of optically thin C II] emission lines indicate a mean chromospheric electron density of log N(sub e) approximately equal 8.9 +/- 0.2 /cc. The profiles of these lines indicate a chromospheric turbulence (v(sub 0) approximately equal 25-36 km/s), which greatly exceeds that seen in either the photosphere or wind. The centroids of optically thin emission lines of Fe II and of the emission wings of self-reversed Fe II lines indicate that they are formed in plasma approximately at rest with respect to the photosphere of the star. This suggests that the acceleration of the wind occurs above the chromospheric regions in which these emission line photons are created. The UV continuum detected by the GHRS clearly traces the mean flux-formation temperature as it increases with height in the chromosphere from a well-defined temperature minimum of 3200 K up to about 4600 K. Emission seen in lines of C III] and Si III] provides evidence of material at higher than chromospheric temperatures in the outer atmosphere of this noncoronal star. The photon-scattering wind produces self-reversals in the strong chromospheric emission lines, which allow us to probe the velocity field of the wind. The velocities to which these self-absorptions extend increase with intrinsic line strength, and thus height in the wind, and therefore directly map the wind acceleration. The width and shape of these self-absorptions reflect a wind turbulence of approximately equal 9-21 km/s. We further characterize the wind by comparing the observations with synthetic profiles generated with the Lamers et al. Sobolev with Exact Integration (SEI) radiative transfer code, assuming simple models of the outer atmospheric structure. These comparisons indicate that the wind in 1994 can be described by a model with a wind acceleration parameter beta approximately 0.9, a terminal velocity of 29-33 km/s, and a mass-loss rate approximately 3 x 10(exp -9) solar M/yr. Modeling of the 3.6 cm radio flux observed in 1997 suggests a more slowly accelerating wind (higher beta) and/or a higher mass-loss rate than inferred from the UV line profiles. These differences may be due to temporal variations in the wind or from limitations in one or both of the models. The discrepancy is currently under investigation.

A Massively Parallel Particle Code for Rarefied Ionized and Neutral Gas Flows in Earth and Planetary Atmospheres, Ionospheres and Magnetospheres

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.

The Physics and Diagnostic Potential of Ultraviolet Spectropolarimetry

NASA Astrophysics Data System (ADS)

Trujillo Bueno, Javier; Landi Degl'Innocenti, Egidio; Belluzzi, Luca

2017-09-01

The empirical investigation of the magnetic field in the outer solar atmosphere is a very important challenge in astrophysics. To this end, we need to identify, measure and interpret observable quantities sensitive to the magnetism of the upper chromosphere, transition region and corona. This paper provides an overview of the physics and diagnostic potential of spectropolarimetry in permitted spectral lines of the ultraviolet solar spectrum, such as the Mg ii h and k lines around 2800 Å, the hydrogen Lyman-α line at 1216 Å, and the Lyman-α line of He ii at 304 Å. The outer solar atmosphere is an optically pumped vapor and the linear polarization of such spectral lines is dominated by the atomic level polarization produced by the absorption and scattering of anisotropic radiation. Its modification by the action of the Hanle and Zeeman effects in the inhomogeneous and dynamic solar atmosphere needs to be carefully understood because it encodes the magnetic field information. The circular polarization induced by the Zeeman effect in some ultraviolet lines (e.g., Mg ii h & k) is also of diagnostic interest, especially for probing the outer solar atmosphere in plages and more active regions. The few (pioneering) observational attempts carried out so far to measure the ultraviolet spectral line polarization produced by optically pumped atoms in the upper chromosphere, transition region and corona are also discussed. We emphasize that ultraviolet spectropolarimetry is a key gateway to the outer atmosphere of the Sun and of other stars.

Atmospheric turbulence characterization with the Keck adaptive optics systems. I. Open-loop data.

PubMed

Schöck, Matthias; Le Mignant, David; Chanan, Gary A; Wizinowich, Peter L; van Dam, Marcos A

2003-07-01

We present a detailed investigation of different methods of the characterization of atmospheric turbulence with the adaptive optics systems of the W. M. Keck Observatory. The main problems of such a characterization are the separation of instrumental and atmospheric effects and the accurate calibration of the devices involved. Therefore we mostly describe the practical issues of the analysis. We show that two methods, the analysis of differential image motion structure functions and the Zernike decomposition of the wave-front phase, produce values of the atmospheric coherence length r0 that are in excellent agreement with results from long-exposure images. The main error source is the calibration of the wave-front sensor. Values determined for the outer scale L0 are consistent between the methods and with typical L0 values found at other sites, that is, of the order of tens of meters.

The Atmospheric Dynamics of alpha Tau (K5 III) - Clues to Understanding the Magnetic Dynamo in Late-Type Giant Stars

NASA Technical Reports Server (NTRS)

Carpenter, Kenneth G.; Airapetian, Vladimir

2008-01-01

Using HST/GHRS, HST/STIS and FUSE archival data for alpha Tau and the CHIANTI spectroscopic code, we have derived line shifts, volumetric emission measures, and plasma density estimates, and calculated filling factors for a number of UV lines forming between 10,000 K and 300,000 K in the outer atmosphere of this red giant star. The data suggest the presence of low-temperature extended regions and high-temperature compact regions, associated with magnetically open and closed structures in the stellar atmosphere, respectively. The signatures of UV lines from alpha Tau can be consistently understood via a model of upward-traveling Alfven waves in a gravitationally stratified atmosphere. These waves cause non-thermal broadening in UV lines due to unresolved wave motions and downward plasma motions in compact magnetic loops heated by resonant Alfven wave heating.

The Atmospheric Dynamics of Alpha Tau (K5 III) - Clues to Understanding the Magnetic Dynamo in Late-Type Giant Stars

NASA Technical Reports Server (NTRS)

Carpenter, Kenneth G.; Airapetian, Vladimir

2008-01-01

Using HST/GHRS, HST/STIS and FUSE archival data for a Tau and the CHIANTI spectroscopic code, we have derived line shifts, volumetric emission measures, and plasma density estimates, and calculated filling factors for a number of UV lines forming between 10,000 K and 300,000 K in the outer atmosphere of this red giant star. The data suggest the presence of low-temperature extended regions and high-temperature compact regions, associated with magnetically open and closed structures in the stellar atmosphere, respectively. The signatures of UV lines from a Tau can be consistently understood via a model of upward-traveling Alfv6n waves in a gravitationally stratified atmosphere. These waves cause nonthermal broadening in UV lines due to unresolved wave motions and downward plasma motions in compact magnetic loops heated by resonant Alfven wave heating.

Origin and evolution of outer solar system atmospheres

NASA Technical Reports Server (NTRS)

Lunine, J. I.

1989-01-01

The origin and evolution of the atmospheres of bodies in the outer solar system is studied on the basis of the abundances of key molecular species. Formation models in which significant infall of icy and rocky planetesimals accompanies planet formation is supported by the enrichment of methane and deuterated species from Jupiter and Neptune. The chemistry of the solar nebula and Titan are discussed. The prospects for obtaining information on the atmosphere of Triton from the Voyager 2 mission are considered. It is found that the mean density of the Pluto-Charon system implies an origin in the rather water-poor solar nebula.

Jupiter's outer atmosphere.

NASA Technical Reports Server (NTRS)

Brice, N. M.

1973-01-01

The current state of the theory of Jupiter's outer atmosphere is briefly reviewed. The similarities and dissimilarities between the terrestrial and Jovian upper atmospheres are discussed, including the interaction of the solar wind with the planetary magnetic fields. Estimates of Jovian parameters are given, including magnetosphere and auroral zone sizes, ionospheric conductivity, energy inputs, and solar wind parameters at Jupiter. The influence of the large centrifugal force on the cold plasma distribution is considered. The Jovian Van Allen belt is attributed to solar wind particles diffused in toward the planet by dynamo electric fields from ionospheric neutral winds, and the consequences of this theory are indicated.

Extended atmospheres of outer planet satellites and comets

NASA Technical Reports Server (NTRS)

Smyth, W. H.; Combi, M. R.

1985-01-01

Model analysis of the extended atmospheres of outer planet satellites and comets are discussed. Understanding the neutral hydrogen distribution in the Saturn system concentrated on assessing the spatial dependence of the lifetime of hydrogen atoms and on obtaining appropriately sorted Lyman ALPHA data from the Voyager 1 UVS instrument. Progress in the area of the extended cometary atmospheres included analysis of Pioneer Venus Layman alpha observations of Comet P/Encke with the fully refined hydrogen cloud model, development of the basic carbon and oxygen models, and planning for the Pioneer Venus UVS observations of Comets P/Giacobini-Zinner and P/Halley.

Formation of a White-Light Jet Within a Quadrupolar Magnetic Configuration

NASA Astrophysics Data System (ADS)

Filippov, Boris; Koutchmy, Serge; Tavabi, Ehsan

2013-08-01

We analyze multi-wavelength and multi-viewpoint observations of a large-scale event viewed on 7 April 2011, originating from an active-region complex. The activity leads to a white-light jet being formed in the outer corona. The topology and evolution of the coronal structures were imaged in high resolution using the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). In addition, large field-of-view images of the corona were obtained using the Sun Watcher using Active Pixel System detector and Image Processing (SWAP) telescope onboard the PRoject for Onboard Autonomy (PROBA2) microsatellite, providing evidence for the connectivity of the coronal structures with outer coronal features that were imaged with the Large Angle Spectrometric Coronagraph (LASCO) C2 on the S olar and Heliospheric Observatory (SOHO). The data sets reveal an Eiffel-tower type jet configuration extending into a narrow jet in the outer corona. The event starts from the growth of a dark area in the central part of the structure. The darkening was also observed in projection on the disk by the Solar TErrestrial RElations Observatory-Ahead (STEREO-A) spacecraft from a different point of view. We assume that the dark volume in the corona descends from a coronal cavity of a flux rope that moved up higher in the corona but still failed to erupt. The quadrupolar magnetic configuration corresponds to a saddle-like shape of the dark volume and provides a possibility for the plasma to escape along the open field lines into the outer corona, forming the white-light jet.

Thermal reactor for afterburning automotive internal combustion engine exhaust gases

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

Masaki, K.; Nagaishi, H.

1974-08-08

A thermal reactor for burning unburned components in exhaust gases of an internal combustion engine before emission to the atmosphere is described. An outer casing has an exhaust gas inlet connected to the exhaust ports, and an inner casing divides the reactor into an outer chamber and an inner chamber. The inner casing has an inlet from the outer chamber, an outlet to the atmosphere, and perforations opening to the outer chamber. An oxidation catalyst in the inner chamber promotes oxidation of the unburned components in the exhaust gases to generate oxidation reaction heat. A first secondary air injection nozzlemore » in the inner chamber between the oxidation catalyst and the outlet and a second secondary air injection nozzle in a portion upstream of the oxidation catalyst inject secondary air into oxidation catalyst.« less

Studies of Elementary Reactions of Chemical Importance in the Atmospheres of Planets

NASA Technical Reports Server (NTRS)

Nesbitt, Fred L.

2003-01-01

The paper discusses the following: 1. F + Cl2 Kinetics. Absolute rate constant for the reaction F(P-2) with Cl2 has been measured using the discharge flow kinetics technique coupled to mass spectrometric detection at T = 180 - 360 K and 1 Torr He nominal pressure. 2. Vapor pressure system. The main effort on the vapor pressure system involved the design and construction of an insulated enclosure ("Bakeout Box") to improve the uniformity of heating during the bakeout process. 3. Sunphotometer System. This period saw the completion of the two-channel sunphotometer, its calibration, and two field deployments. 4. Vibrational-to-translation (V-T) transfer rates for light hydrocarbons at low temperatures are important parameters in thermal-structure models of the upper atmospheres of the outer planets and their satellites. However, the required data are either simply not available or do not extend to the low temperatures found in those systems. Because methane is such an important constituent in outer planet atmospheres, we have initiated a program to measure the temperature dependence of (V-T) rates for its relaxation by appropriate collision partners. 5. The central focus of this research has been the vapor phase nucleation and growth of metals/refractory species into small particles and the aggregation of these primary particles into larger structures. These topics are part of the broader goal of understanding the conditions under which interstellar dust grains condense from stellar outflows and how these small dust grains coagulate into larger bodies such as planetesimals or planets.

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)

The solar-terrestrial environment. An introduction to geospace - the science of the terrestrial upper atmosphere, ionosphere and magnetosphere.

NASA Astrophysics Data System (ADS)

Hargreaves, J. K.

This textbook is a successor to "The upper atmosphere and solar-terrestrial relations" first published in 1979. It describes physical conditions in the upper atmosphere and magnetosphere of the Earth. This geospace environment begins 70 kilometres above the surface of the Earth and extends in near space to many times the Earth's radius. It is the region of near-Earth environment where the Space Shuttle flies, the aurora is generated, and the outer atmosphere meets particles streaming out of the sun. The account is introductory. The intent is to present basic concepts, and for that reason the mathematical treatment is not complex. There are three introductory chapters that give basic physics and explain the principles of physical investigation. The principal material contained in the main part of the book covers the neutral and ionized upper atmosphere, the magetosphere, and structures, dynamics, disturbances and irregularities. The concluding chapter deals with technological applications.

Roles of silica and lignin in horsetail (Equisetum hyemale), with special reference to mechanical properties

NASA Astrophysics Data System (ADS)

Yamanaka, Shigeru; Sato, Kanna; Ito, Fuyu; Komatsubara, Satoshi; Ohata, Hiroshi; Yoshino, Katsumi

2012-02-01

This research deals with detailed analyses of silica and lignin distribution in horsetail with special reference to mechanical strength. Scanning electron images of a cross-section of an internode showed silica deposited densely only around the outer epidermis. Detailed histochemical analyses of lignin showed no lignin deposition in the silica-rich outer internodes of horsetail, while a characteristic lignin deposition was noticed in the vascular bundle in inner side of internodes. To analyze the structure of horsetail from a mechanical viewpoint, we calculated the response of a model structure of horsetail to a mechanical force applied perpendicularly to the long axis by a finite element method. We found that silica distributed in the outer epidermis may play the major structural role, with lignin's role being limited ensuring that the vascular bundle keep waterproof. These results were in contrast to more modern tall trees like gymnosperms, for which lignin provides mechanical strength. Lignin has the advantage of sticking to cellulose, hemicellulose, and other materials. Such properties make it possible for plants containing lignin to branch. Branching of tree stems aids in competing for light and other atmospheric resources. This type of branching was impossible for ancient horsetails, which relied on the physical properties of silica. From the evolutional view points, over millennia in trees with high lignin content, true branching, and many chlorophyll-containing leaves developed.

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.

Atmospheric Mining in the Outer Solar System: Outer Planet Orbital Transfer and Lander Analyses

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2016-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. Analyses of orbital transfer vehicles (OTVs), landers, and the issues with in-situ resource utilization (ISRU) mining factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points. For analyses of round trip OTV flights from Uranus to Miranda or Titania, a 10-Megawatt electric (MWe) OTV power level and a 200-metric ton (MT) lander payload were selected based on a relative short OTV trip time and minimization of the number of lander flights. A similar optimum power level is suggested for OTVs flying from low orbit around Neptune to Thalassa or Triton. Several moon base sites at Uranus and Neptune and the OTV requirements to support them are also addressed.

Atmospheric Mining in the Outer Solar System: Outer Planet Orbital Transfer and Lander Analyses

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2016-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. Analyses of orbital transfer vehicles (OTVs), landers, and the issues with in-situ resource utilization (ISRU) mining factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points. For analyses of round trip OTV flights from Uranus to Miranda or Titania, a 10- Megawatt electric (MWe) OTV power level and a 200 metricton (MT) lander payload were selected based on a relative short OTV trip time and minimization of the number of lander flights. A similar optimum power level is suggested for OTVs flying from low orbit around Neptune to Thalassa or Triton. Several moon base sites at Uranus and Neptune and the OTV requirements to support them are also addressed.

A Sounding Rocket Experiment for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

NASA Technical Reports Server (NTRS)

Kubo, M.; Kano, R.; Kobayashi, K.; Ishikawa, R.; Bando, T.; Narukage, N.; Katsukawa, Y.; Ishikawa, S.; Suematsu, Y.; Hara, H.;

Atmospheric Mining in the Outer Solar System: Resource Capturing, Exploration, and Exploitation

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2015-01-01

Atmospheric mining in the outer solar system (AMOSS) has been investigated as a means of fuel production for high-energy propulsion and power. Fusion fuels such as helium 3 (He-3) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. 3He and hydrogen (deuterium, etc.) were the primary gases of interest, with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of AMOSS. These analyses included the gas capturing rate, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues. While capturing 3He, large amounts of hydrogen and helium 4 (He-4) are produced. With these two additional gases, the potential exists for fueling small and large fleets of additional exploration and exploitation vehicles. Additional aerospacecraft or other aerial vehicles (UAVs, balloons, rockets, etc.) could fly through the outer-planet atmosphere to investigate cloud formation dynamics, global weather, localized storms or other disturbances, wind speeds, the poles, and so forth. Deep-diving aircraft (built with the strength to withstand many atmospheres of pressure) powered by the excess hydrogen or 4He may be designed to probe the higher density regions of the gas giants.

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.

Ground Based Studies of the Outer Planets

NASA Technical Reports Server (NTRS)

Trafton, Laurence M.

2005-01-01

This report covers progress to date under this grant on our continuing program to conduct ground based studies of the outer solar system planets and satellites, with emphasis on spectroscopy and atmospheric phenomena. The research continues under our new PAST grant, NNG04G131G beginning 5/1/2004. The original period of performance of the subject grant was 3/1/2001 to 2/28/2004, but was extended one year at no cost. Although there is some overlap in the scientific projects conducted during the extended year with those of the new grant, this report is confined to the portion of the work funded under NAG5-10435. The primary goals for this grant period were a comparative study of outer planet thermospheres/ionospheres near solar maximum, extended to the mid-IR, and the investigation of molecular dimers in outer solar system atmospheres. This project supports NASA's planned space missions, Jupiter Polar Orbiter, outer Planet Microprobes, and the recent Cassini flyby of Jupiter. It also supports the OSS strategic plan themes, The Exploration of the Solar System and The Sun-Earth Connection/ Understanding comparative planetary space environments.

Wearable Atmospheric Pressure Plasma Fabrics Produced by Knitting Flexible Wire Electrodes for the Decontamination of Chemical Warfare Agents

PubMed Central

Jung, Heesoo; Seo, Jin Ah; Choi, Seungki

2017-01-01

One of the key reasons for the limited use of atmospheric pressure plasma (APP) is its inability to treat non-flat, three-dimensional (3D) surface structures, such as electronic devices and the human body, because of the rigid electrode structure required. In this study, a new APP system design—wearable APP (WAPP)—that utilizes a knitting technique to assemble flexible co-axial wire electrodes into a large-area plasma fabric is presented. The WAPP device operates in ambient air with a fully enclosed power electrode and grounded outer electrode. The plasma fabric is flexible and lightweight, and it can be scaled up for larger areas, making it attractive for wearable APP applications. Here, we report the various plasma properties of the WAPP device and successful test results showing the decontamination of toxic chemical warfare agents, namely, mustard (HD), soman (GD), and nerve (VX) agents. PMID:28098192

Wearable Atmospheric Pressure Plasma Fabrics Produced by Knitting Flexible Wire Electrodes for the Decontamination of Chemical Warfare Agents

NASA Astrophysics Data System (ADS)

Jung, Heesoo; Seo, Jin Ah; Choi, Seungki

2017-01-01

One of the key reasons for the limited use of atmospheric pressure plasma (APP) is its inability to treat non-flat, three-dimensional (3D) surface structures, such as electronic devices and the human body, because of the rigid electrode structure required. In this study, a new APP system design—wearable APP (WAPP)—that utilizes a knitting technique to assemble flexible co-axial wire electrodes into a large-area plasma fabric is presented. The WAPP device operates in ambient air with a fully enclosed power electrode and grounded outer electrode. The plasma fabric is flexible and lightweight, and it can be scaled up for larger areas, making it attractive for wearable APP applications. Here, we report the various plasma properties of the WAPP device and successful test results showing the decontamination of toxic chemical warfare agents, namely, mustard (HD), soman (GD), and nerve (VX) agents.

Wearable Atmospheric Pressure Plasma Fabrics Produced by Knitting Flexible Wire Electrodes for the Decontamination of Chemical Warfare Agents.

PubMed

Jung, Heesoo; Seo, Jin Ah; Choi, Seungki

2017-01-18

One of the key reasons for the limited use of atmospheric pressure plasma (APP) is its inability to treat non-flat, three-dimensional (3D) surface structures, such as electronic devices and the human body, because of the rigid electrode structure required. In this study, a new APP system design-wearable APP (WAPP)-that utilizes a knitting technique to assemble flexible co-axial wire electrodes into a large-area plasma fabric is presented. The WAPP device operates in ambient air with a fully enclosed power electrode and grounded outer electrode. The plasma fabric is flexible and lightweight, and it can be scaled up for larger areas, making it attractive for wearable APP applications. Here, we report the various plasma properties of the WAPP device and successful test results showing the decontamination of toxic chemical warfare agents, namely, mustard (HD), soman (GD), and nerve (VX) agents.

Outer atmospheres of cool stars. XII - A survey of IUE ultraviolet emission line spectra of cool dwarf stars

NASA Technical Reports Server (NTRS)

Linsky, J. L.; Bornmann, P. L.; Carpenter, K. G.; Hege, E. K.; Wing, R. F.; Giampapa, M. S.; Worden, S. P.

1982-01-01

Quantitative information is obtained on the chromospheres and transition regions of M dwarf stars, in order to determine how the outer atmospheres of dMe stars differ from dM stars and how they compare with the outer atmospheres of quiet and active G and K type dwarfs. IUE spectra of six dMe and four dM stars, together with ground-based photometry and spectroscopy of the Balmer and Ca II H and K lines, show no evidence of flares. It is concluded, regarding the quiescent behavior of these stars, that emission-line spectra resemble that of the sun and contain emission lines formed in regions with 4000-20,000 K temperatures that are presumably analogous to the solar chromosphere, as well as regions with temperatures of 20,000-200,000 K that are presumably analogous to the solar transition region. Emission-line surface fluxes are proportional to the emission measure over the range of temperatures at which the lines are formed.

Photochemical Studies of Chemistry in the Outer Solar System

NASA Technical Reports Server (NTRS)

Yung, Yuk L.

2003-01-01

The goal of the proposed science investigation is to gain a quantitative understanding of chemical processes and their coupling with atmospheric dynamics in the reducing atmospheres of the outer solar system, with a particular focus on Infrared Space Observatory (ISO) observations and future experiments such as the Cassini Mission to Saturn and Titan. The proposed work is divided into two related tasks. We have carried out a systematic comparison between atmospheric models for every giant planet and Titan, which employ a consistent set of photochemical reactions. Combined with recent observations of hydrocarbon species by ISO, this can provide the most rigorous test of our current understanding of the photochemistry of hydrocarbon in the outer solar system. The emphasis will be on the methyl radical (CH3), first detected by IS0 in the atmospheres of Saturn and Neptune (Bezard et al. 1998). CH3 is one of the most important radicals in the hydrocarbon photochemistry because it is the primary product of methane photolysis and plays an essential role in forming C2H6, the most abundant and stable C2 species. A fundamental understanding of the distribution of CH3 provides unique insights into the chemistry of hydrocarbons as well as comparative planetology.

The Thermal States of Accreting Planets: From Mars-like Embryos to a MAD Earth

NASA Astrophysics Data System (ADS)

Stewart, S. T.; Lock, S. J.

2015-12-01

The thermal states of rocky planets can vary widely during the process of accretion. The thermal structure affects several major processes on the growing planet, including the mechanics of core formation, pressure-temperature conditions for metal-silicate equilibration, mixing, and atmospheric erosion. Because impact energy is distributed heterogeneously, accretional energy is preferentially deposited in the gravitationally re-equilibrated outer layers of the planet for both small and giant impacts. The resulting stably stratified structure inhibits complete mixing within the mantle. Initially, the specific energy of giant impacts between Mars-mass embryos leads to melting of the mantle. However, as planet formation progresses, the specific energies of giant impacts increase and can drive the mantle into a transient supercritical state. In the hottest regions of the planet, metal and silicates are miscible, and metal exsolution occurs as the structure cools. The cooling time of the supercritical structure is typically longer than the timescale for metal segregation to the core. Thus, these high temperature excursions during planet formation are significant for understanding metal-silicate equilibration. Furthermore, when a supercritical planet is also rapidly rotating, the mantle, atmosphere and disk (MAD) form a continuous dynamic and thermodynamic structure. Lunar origin by condensation from a MAD Earth can explain the major characteristics of the Moon (Lock et al., this meeting). One of the greatest uncertainties in understanding the thermal states of planets during accretion is the changing composition and mass of the atmosphere. After the dispersal of the solar nebula, the thermal boundary condition imposed by the atmosphere can vary between silicate vapor and condensed ices. The coupled problem of atmospheric origin and planetary accretion can be used to constrain the many uncertainties in the growth and divergence of the terrestrial planets in our solar system.

Earth Science

NASA Image and Video Library

1995-12-02

The Solar Heliospheric Observatory (SOHO) is launched atop an ATLAS-IIAS expendable launch vehicle. Liftoff from launch complex 36B at Cape Canaveral Air Station marked the 10th Atlas launch from the Eastern range for 1995. SOHO is a cooperative effort involving NASA and the European Space Agency (ESA) within the framework of the International Solar-Terrestrial Physics Program. During its 2-year mission, the SOHO spacecraft gathered data on the internal structure of the Sun, its extensive outer atmosphere and the origin of the solar wind.

Computational and experimental study of atmospheric moisture in ceramic blocks filled with waste fibres in winter season

NASA Astrophysics Data System (ADS)

Stastnik, S.

2016-06-01

Development of materials for vertical outer building structures tends to application of hollow clay blocks filled with some appropriate insulation material. Ceramic fittings provide high thermal resistance, but the walls built from them suffer from condensation of air humidity in winter season frequently. The paper presents the computational simulation and experimental laboratory validation of moisture behaviour of such masonry with insulation prepared from waste fibres under the Central European climatic conditions.

The Atmospheric Dynamics of Alpha Tau (K5 III) -- Clues to Understanding the Magnetic Dynamo

NASA Technical Reports Server (NTRS)

Carpenter Kenneth G.

2008-01-01

Using HST/GHRS, HST/STIS and FUSE archival data for (alpha) Tau and the CHIANTI spectroscopic code, we have derived line shifts, volumetric emission measures, and plasma density estimates, and calculated filling factors for a number of UV lines forming between 10,000 K and 300,000 K in the outer atmosphere of this red giant star. The data suggest the presence of low-temperature extended regions and high-temperature compact regions, associated with magnetically open and closed structures in the stellar atmosphere, respectively. The signatures of UV lines from Alpha Tau can be consistently understood via a model of upward-traveling Alfven waves in a gravitationally stratified atmosphere. These wakes cause non-thermal broadening in UV lines due to unresolved wave motions and downward plasma motions in compact magnetic loops heated by resonant .4lf\\en wave heating. We discuss implications of this interpretation for understanding the nature of magnetic dynamos operating in late-type giants.

Effect of artificial length scales in large eddy simulation of a neutral atmospheric boundary layer flow: A simple solution to log-layer mismatch

NASA Astrophysics Data System (ADS)

Chatterjee, Tanmoy; Peet, Yulia T.

2017-07-01

A large eddy simulation (LES) methodology coupled with near-wall modeling has been implemented in the current study for high Re neutral atmospheric boundary layer flows using an exponentially accurate spectral element method in an open-source research code Nek 5000. The effect of artificial length scales due to subgrid scale (SGS) and near wall modeling (NWM) on the scaling laws and structure of the inner and outer layer eddies is studied using varying SGS and NWM parameters in the spectral element framework. The study provides an understanding of the various length scales and dynamics of the eddies affected by the LES model and also the fundamental physics behind the inner and outer layer eddies which are responsible for the correct behavior of the mean statistics in accordance with the definition of equilibrium layers by Townsend. An economical and accurate LES model based on capturing the near wall coherent eddies has been designed, which is successful in eliminating the artificial length scale effects like the log-layer mismatch or the secondary peak generation in the streamwise variance.

EMERGENCE OF GRANULAR-SIZED MAGNETIC BUBBLES THROUGH THE SOLAR ATMOSPHERE. II. NON-LTE CHROMOSPHERIC DIAGNOSTICS AND INVERSIONS

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

Rodríguez, Jaime de la Cruz; Hansteen, Viggo; Ortiz, Ada

Magnetic flux emergence into the outer layers of the Sun is a fundamental mechanism for releasing energy into the chromosphere and the corona. In this paper, we study the emergence of granular-sized flux concentrations and the structuring of the corresponding physical parameters and atmospheric diagnostics in the upper photosphere and in the chromosphere. We make use of a realistic 3D MHD simulation of the outer layers of the Sun to study the formation of the Ca ii 8542 line. We also derive semi-empirical 3D models from non-LTE inversions of our observations. These models contain information on the line-of-sight stratifications ofmore » temperature, velocity, and the magnetic field. Our analysis explains the peculiar Ca ii 8542 Å profiles observed in the flux emerging region. Additionally, we derive detailed temperature and velocity maps describing the ascent of a magnetic bubble from the photosphere to the chromosphere. The inversions suggest that, in active regions, granular-sized bubbles emerge up to the lower chromosphere where the existing large-scale field hinders their ascent. We report hints of heating when the field reaches the chromosphere.« less

Outer planet entry probe system study. Volume 4: Common Saturn/Uranus probe studies

NASA Technical Reports Server (NTRS)

1973-01-01

Results are summarized of a common scientific probe study to explore the atmospheres of Saturn and Uranus. This was a three-month follow-on effort to the Outer Planet Entry Probe System study. The report presents: (1) a summary, conclusions and recommendations of this study, (2) parametric analysis conducted to support the two system definitions, (3) common Saturn/Uranus probe system definition using the Science Advisory Group's exploratory payload and, (4) common Saturn/Uranus probe system definition using an expanded science complement. Each of the probe system definitions consists of detailed discussions of the mission, science, system and subsystems including telecommunications, data handling, power, pyrotechnics, attitude control, structures, propulsion, thermal control and probe-to-spacecraft integration. References are made to the contents of the first three volumes where it is feasible to do so.

Double-Layered Atmospheric Pressure Plasma Jet

NASA Astrophysics Data System (ADS)

Choi, Jaegu; Matsuo, Keita; Yoshida, Hidekazu; Namihira, Takao; Katsuki, Sunao; Akiyama, Hidenori

2009-08-01

In this paper, we present a double-layered atmospheric pressure plasma jet (DLAPPJ) that is expected to improve conventional single-layered atmospheric pressure plasma jets. With the additional introduction of nitrogen gas into the outer nozzle between the inner and outer tubes, the plasma plume is boosted, resulting in a brighter and longer plasma torch, which may have more radicals and which may broaden the application range of atmospheric pressure plasma jets. The characteristics of the proposed device were investigated with the measurement of the visible torch length, wettability tests and optical emission spectroscopy. The results obtained imply that the DLAPPJ can be used for target-based plasma treatments, that is, (a) oxidation-related applications, such as surface treatment, biological decontamination and apoptosis induction, and (b) nitrification-related applications such as NO generation for wound healing and surface modification, by controlling radicals in plasmas.

The atmosphere of a dirty-clathrate cometary nucleus - A two-phase, multifluid model

NASA Astrophysics Data System (ADS)

Marconi, M. L.; Mendis, D. A.

1983-10-01

The dynamical and thermal structure of a dirty-clathrate cometary nucleus' gas atmosphere is presently given a self-consistent, transonic multifluid solution in which, although the heavy neutron and ion species are treated as a single fluid in the collision-dominated region, the photoproduced H is treated separately. The thermal profile of the atmosphere thus obtained is entirely different from those predicted by the earlier, single-fluid models as well as the multifluid models which assumed equipartition of energy between electrons and ions. While the electron gas, like the neutrals and the ions, cools due to expansion, its main mode of energy loss in the inner coma is by way of inelastic collisions with the predominant H2O molecule. The high electron temperature in the outer coma also decreases the efficiency of electron removal by dissociative recombination, thereby increasing electron density throughout the coma.

Titan Upper Atmosphere: A factory of hydrocarbons

NASA Image and Video Library

2005-04-22

During its closest flyby of Saturn's moon Titan on April 16, the Cassini spacecraft came within 1,025 kilometers (637 miles) of the moon's surface and found that the outer layer of the thick, hazy atmosphere is brimming with complex hydrocarbons. This figure shows a mass spectrum of Titan's ionosphere near 1,200 kilometers (746 miles) above its surface. The mass range covered goes from hydrogen at 1 atomic mass unit per elementary charge (Dalton) to 99 Daltons. This mass range includes compounds with 1, 2, 3, 4, 5, 6, and 7 carbons as the base structure (as indicated in the figure label). The identified compounds include multiple carbon molecules and carbon-nitrogen bearing species as well. http://photojournal.jpl.nasa.gov/catalog/PIA07865

Hubble 2020: Outer Planet Atmospheres Legacy (OPAL) Program

NASA Astrophysics Data System (ADS)

Simon, Amy

2017-08-01

Long time base observations of the outer planets are critical in understanding the atmospheric dynamics and evolution of the gas giants. We propose yearly monitoring of each giant planet for the remainder of Hubble's lifetime to provide a lasting legacy of increasingly valuable data for time-domain studies. The Hubble Space Telescope is a unique asset to planetary science, allowing high spatial resolution data with absolute photometric knowledge. For the outer planets, gas/ice giant planets Jupiter, Saturn, Uranus and Neptune, many phenomena happen on timescales of years to decades, and the data we propose are beyond the scope of a typical GO program. Hubble is the only platform that can provide high spatial resolution global studies of cloud coloration, activity, and motion on a consistent time basis to help constrain the underlying mechanics.

Toxicokinetic Study for Investigation of Sex Differences in Internal Dosimetry of Jet Propulsion Fuel 8 (JP-8) in the Laboratory Rat

DTIC Science & Technology

2013-07-26

8 (2000 mg/m 3 ) may have produced transient impairment of rat cochlear outer hair cell function in the absence of noise (Fechter et al., 2010); the...system is a dynamic, non- rebreathing system. In this system, an exposure atmosphere flow rate of approximately 0.5 L/min per open port was maintained...exposure atmosphere flow to the chamber or the exhaust. The outer plenum of the nose-only exposure system carried the animals’ exhaled breath and excess

Modeling mass loss from B(e) stars

NASA Technical Reports Server (NTRS)

Cassinelli, J. P.; Schulte-Ladbeck, R. E.; Abbott, M.; Poe, C. H.

1989-01-01

It was suggested by Zickgraf et al. (1986) that the outer atmospheres of some B(e) stars have a two-component structure: a fast, radiation-driven wind from the pole, and a dense, slow outflow from the equator. Poe et al. (1989) developed this theory to explain the momentum problem associated with WR stars. This paper uses the multiforce wind theory of Poe et al. to model the B(e) outflow phenomenon. Two general questions are investigated: (1) whether B(e) stars can be rotating near critical speed, and if so, (2) what constraints can be placed on the parameters that determine the two-component flow structure.

Energetic neutral atom emissions from Titan interaction with Saturn's magnetosphere.

PubMed

Mitchell, D G; Brandt, P C; Roelof, E C; Dandouras, J; Krimigis, S M; Mauk, B H

2005-05-13

The Cassini Magnetospheric Imaging Instrument (MIMI) observed the interaction of Saturn's largest moon, Titan, with Saturn's magnetosphere during two close flybys of Titan on 26 October and 13 December 2004. The MIMI Ion and Neutral Camera (INCA) continuously imaged the energetic neutral atoms (ENAs) generated by charge exchange reactions between the energetic, singly ionized trapped magnetospheric ions and the outer atmosphere, or exosphere, of Titan. The images reveal a halo of variable ENA emission about Titan's nearly collisionless outer atmosphere that fades at larger distances as the exospheric density decays exponentially. The altitude of the emissions varies, and they are not symmetrical about the moon, reflecting the complexity of the interactions between Titan's upper atmosphere and Saturn's space environment.

Atmosphere Explorer set for launch

NASA Technical Reports Server (NTRS)

1975-01-01

The Atmosphere Explorer-D (Explorer-54) is described which will explore in detail an area of the earth's outer atmosphere where important energy transfer, atomic and molecular processes, and chemical reactions occur that are critical to the heat balance of the atmosphere. Data are presented on the mission facts, launch vehicle operations, AE-D/Delta flight events, spacecraft description, scientific instruments, tracking, and data acquisition.

Solar System Exploration Augmented by Lunar and Outer Planet Resource Utilization: Historical Perspectives and Future Possibilities

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2014-01-01

Establishing a lunar presence and creating an industrial capability on the Moon may lead to important new discoveries for all of human kind. Historical studies of lunar exploration, in-situ resource utilization (ISRU) and industrialization all point to the vast resources on the Moon and its links to future human and robotic exploration. In the historical work, a broad range of technological innovations are described and analyzed. These studies depict program planning for future human missions throughout the solar system, lunar launched nuclear rockets, and future human settlements on the Moon, respectively. Updated analyses based on the visions presented are presented. While advanced propulsion systems were proposed in these historical studies, further investigation of nuclear options using high power nuclear thermal propulsion, nuclear surface power, as well as advanced chemical propulsion can significantly enhance these scenarios. Robotic and human outer planet exploration options are described in many detailed and extensive studies. Nuclear propulsion options for fast trips to the outer planets are discussed. To refuel such vehicles, atmospheric mining in the outer solar system has also been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses have investigated resource capturing aspects of atmospheric mining in the outer solar system. These analyses included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists.

Solar System Exploration Augmented by Lunar and Outer Planet Resource Utilization: Historical Perspectives and Future Possibilities

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2014-01-01

Establishing a lunar presence and creating an industrial capability on the Moon may lead to important new discoveries for all of human kind. Historical studies of lunar exploration, in-situ resource utilization (ISRU) and industrialization all point to the vast resources on the Moon and its links to future human and robotic exploration. In the historical work, a broad range of technological innovations are described and analyzed. These studies depict program planning for future human missions throughout the solar system, lunar launched nuclear rockets, and future human settlements on the Moon, respectively. Updated analyses based on the visions presented are presented. While advanced propulsion systems were proposed in these historical studies, further investigation of nuclear options using high power nuclear thermal propulsion, nuclear surface power, as well as advanced chemical propulsion can significantly enhance these scenarios. Robotic and human outer planet exploration options are described in many detailed and extensive studies. Nuclear propulsion options for fast trips to the outer planets are discussed. To refuel such vehicles, atmospheric mining in the outer solar system has also been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as helium 3 (3He) and hydrogen (H2) can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and H2 (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses have investigated resource capturing aspects of atmospheric mining in the outer solar system. These analyses included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists.

Chemistry of the outer planets

NASA Technical Reports Server (NTRS)

Scattergood, Thomas W.

1992-01-01

Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

Electron impact cross-sections and cooling rates for methane. [in thermal balance of electrons in atmospheres and ionospheres of planets and satellites in outer solar system

NASA Technical Reports Server (NTRS)

Gan, L.; Cravens, T. E.

1992-01-01

Energy transfer between electrons and methane gas by collisional processes plays an important role in the thermal balance of electrons in the atmospheres and ionospheres of planets and satellites in the outer solar system. The literature is reviewed for electron impact cross-sections for methane in this paper. Energy transfer rates are calculated for elastic and inelastic processes using a Maxwellian electron distribution. Vibrational, rotational, and electronic excitation and ionization are included. Results are presented for a wide range of electron temperatures and neutral temperatures.

Evidence for a temperature rise in the outer layers of alpha Lyrae, from Copernicus observations of Lyman-alpha

NASA Technical Reports Server (NTRS)

Praderie, F.; Simonneau, E.; Snow, T. P., Jr.

1975-01-01

Copernicus satellite observations of the Ly-alpha profiles in alpha Lyrae (Vega) are used to determine whether classical radiative-equilibrium LTE model atmospheres can fit the thermal structure in the outer layers of that star. Two plane-parallel LTE model photospheres of alpha Lyrae are considered: a line-blanketed radiative-equilibrium model with an effective temperature of 9650 K and log g of 4.05, and the same model with a temperature of 9500 K and log g of 4.0. The profiles of the Ly-alpha wings are computed, and it is found that classical LTE models are unable to predict either the observed violet wing or the red wing longwards of 1239 A, regardless of the line source function. It is concluded that the electron temperature must increase outwards over the surface value reached in radiative equilibrium.

Nature, theory and modelling of geophysical convective planetary boundary layers

NASA Astrophysics Data System (ADS)

Zilitinkevich, Sergej

2015-04-01

Geophysical convective planetary boundary layers (CPBLs) are still poorly reproduced in oceanographic, hydrological and meteorological models. Besides the mean flow and usual shear-generated turbulence, CPBLs involve two types of motion disregarded in conventional theories: 'anarchy turbulence' comprised of the buoyancy-driven plumes, merging to form larger plumes instead of breaking down, as postulated in conventional theory (Zilitinkevich, 1973), large-scale organised structures fed by the potential energy of unstable stratification through inverse energy transfer in convective turbulence (and performing non-local transports irrespective of mean gradients of transporting properties). C-PBLs are strongly mixed and go on growing as long as the boundary layer remains unstable. Penetration of the mixed layer into the weakly turbulent, stably stratified free flow causes turbulent transports through the CPBL outer boundary. The proposed theory, taking into account the above listed features of CPBL, is based on the following recent developments: prognostic CPBL-depth equation in combination with diagnostic algorithm for turbulence fluxes at the CPBL inner and outer boundaries (Zilitinkevich, 1991, 2012, 2013; Zilitinkevich et al., 2006, 2012), deterministic model of self-organised convective structures combined with statistical turbulence-closure model of turbulence in the CPBL core (Zilitinkevich, 2013). It is demonstrated that the overall vertical transports are performed mostly by turbulence in the surface layer and entrainment layer (at the CPBL inner and outer boundaries) and mostly by organised structures in the CPBL core (Hellsten and Zilitinkevich, 2013). Principal difference between structural and turbulent mixing plays an important role in a number of practical problems: transport and dispersion of admixtures, microphysics of fogs and clouds, etc. The surface-layer turbulence in atmospheric and marine CPBLs is strongly enhanced by the velocity shears in horizontal branches of organised structures. This mechanism (Zilitinkevich et al., 2006), was overlooked in conventional local theories, such as the Monin-Obukhov similarity theory, and convective heat/mass transfer law: Nu~Ra1/3, where Nu and Ra are the Nusselt number and Raleigh numbers. References Hellsten A., Zilitinkevich S., 2013: Role of convective structures and background turbulence in the dry convective boundary layer. Boundary-Layer Meteorol. 149, 323-353. Zilitinkevich, S.S., 1973: Shear convection. Boundary-Layer Meteorol. 3, 416-423. Zilitinkevich, S.S., 1991: Turbulent Penetrative Convection, Avebury Technical, Aldershot, 180 pp. Zilitinkevich S.S., 2012: The Height of the Atmospheric Planetary Boundary layer: State of the Art and New Development - Chapter 13 in 'National Security and Human Health Implications of Climate Change', edited by H.J.S. Fernando, Z. Klaić, J.L. McKulley, NATO Science for Peace and Security Series - C: Environmental Security (ISBN 978-94-007-2429-7), Springer, 147-161. Zilitinkevich S.S., 2013: Atmospheric Turbulence and Planetary Boundary Layers. Fizmatlit, Moscow, 248 pp. Zilitinkevich, S.S., Hunt, J.C.R., Grachev, A.A., Esau, I.N., Lalas, D.P., Akylas, E., Tombrou, M., Fairall, C.W., Fernando, H.J.S., Baklanov, and A., Joffre, S.M., 2006: The influence of large convective eddies on the surface layer turbulence. Quart. J. Roy. Met. Soc. 132, 1423-1456. Zilitinkevich S.S., Tyuryakov S.A., Troitskaya Yu. I., Mareev E., 2012: Theoretical models of the height of the atmospheric planetary boundary layer and turbulent entrainment at its upper boundary. Izvestija RAN, FAO, 48, No.1, 150-160 Zilitinkevich, S.S., Elperin, T., Kleeorin, N., Rogachevskii, I., Esau, I.N., 2013: A hierarchy of energy- and flux-budget (EFB) turbulence closure models for stably stratified geophysical flows. Boundary-Layer Meteorol. 146, 341-373.

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.

MAVEN - Mars Atmosphere and Volatile EvolutioN Mission

NASA Technical Reports Server (NTRS)

Grebowsky, Joseph M.; Jakosky, Bruce M.

2011-01-01

NASA's MAVEN mission (to be launched in late 2013) is the first mission to Mars devoted to sampling all of the upper atmosphere neutral and plasma environments, including the well-mixed atmosphere, the exosphere, ionosphere, outer magnetosphere and near-Mars solar wind. It will fill in some measurement gaps remaining from the successful Mars Global Surveyor and the on-going Mars Express missions. The primary science objectives of MAVEN are: 1. Provide a comprehensive picture of the present state of the upper atmosphere and ionosphere of Mars; 2. Understand the processes controlling the present state; and 3. Determine how loss of volatiles to outer space in the present epoch varies with changing solar condition - EUY, solar wind and interplanetary magnetic field measurements will provide the varying solar energy inputs into the system. Knowing how these processes respond to the Sun's energy inputs in the current epoch will provide a framework for projecting atmospheric processes back in time to profile MARS' atmospheric evolution and to explore "where the water went", A description will be given of the science objectives, the instruments, and the current status of the project, emphasizing the value of having collaborations between the MAVEN project and the Mars upper atmosphere science community.

Earth Science

NASA Image and Video Library

1995-12-01

The reflection of the Atlas IIAS expendable launch vehicle with the Solar Heliospheric Observatory (SOHO) inside its payload fairing can be seen on the surface of a retention pond at Launch Pad 36B on Cape Canaveral Air Station just hours before liftoff. SOHO is a cooperative effort involving NASA and the European Space Agency (ESA) within the framework of the International Solar-Terrestrial Physics Program. During its 2-year mission, the SOHO spacecraft will gather data on the internal structure of the Sun, its extensive outer atmosphere and the origin of the solar wind.

Asteroid volatiles inventory

NASA Technical Reports Server (NTRS)

Lebofsky, L. A.; Jones, T. D.; Herbert, F.

1989-01-01

Asteroids appear in light of telescopic and meteority studies to be the most accessible repositories of early solar system history available. In the cooler regions of the outer asteroid belt, apparently unaffected by severe heating, the C, P, and D populations appear to harbor significant inventories of volatiles; the larger primordial belt population may have had an even greater percentage of volatile-rich, low-albedo asteroids, constituting a potent asteroid for veneering early terrestrial planet atmospheres. The volatile-rich asteroids contain carbon, structurally bound and adsorbed water, as well as remnants of interstellar material predating the solar system.

Momentum and energy balance in late-type stellar winds

NASA Technical Reports Server (NTRS)

Macgregor, K. B.

1981-01-01

Observations at ultraviolet and X-ray wavelengths indicate that the classical picture of a static stellar atmosphere containing a radiative equilibrium temperature distribution is inapplicable to the majority of late type stars. Mass loss and the presence of atmospheric regions characterized by gas temperatures in excess of the stellar effective temperature appear to be almost ubiquitous throughout the HR diagram. Evidence pertaining to the thermal and dynamical structure of the outer envelopes of cool stars is summarized. These results are compared with the predictions of several theoretical models which were proposed to account for mass loss from latetype stars. Models in which the outflow is thermally radiatively, or wave driven are considered for identification of the physical processes responsible for the observed wind properties. The observed variation of both the wind, thermal and dynamical structure as one proceeds from the supergiant branch toward the main sequence in the cool portion of the HR diagram give consideration to potential mechanisms for heating and cooling the flow from low gravity stars.

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.

Experimental evaluation of outer planets probe thermal insulation concepts

NASA Technical Reports Server (NTRS)

Grote, M. G.; Mezines, S. A.

1976-01-01

An experimental program was conducted to evaluate various thermal insulation concepts for use in the Outer Planets Probe (OPP) during entry and descent into the atmospheres of Jupiter, Saturn, and Uranus. Phenolic fiberglass honeycomb specimens representative of the OPP structure were packed and tested with various fillers: Thermal conductivity measurements were made over a temperature range of 300 K to 483 K and pressures from vacuum up to 10 atmospheres in helium and nitrogen gas environments. The conductivity results could not be fully explained so new test specimens were designed with improved venting characteristics, and tested to determine the validity of the original data. All of the conductivity data showed results that were substantially higher than expected. The original test data in helium were lower than the data from the redesigned specimens, probably due to inadequate venting of nitrogen gas from the original specimens. The thermal conductivity test results show only a marginal improvement in probe thermal protection performance for a filled honeycomb core compared to an unfilled core. In addition, flatwise tension tests showed a severe bond strength degradation due to the inclusion of either the powder or foam fillers. In view of these results, it is recommended that the baseline OPP design utilize an unfilled core.

Theoretical studies of volatile processes in the outer solar system

NASA Technical Reports Server (NTRS)

Lunine, Jonathan I.

1991-01-01

Four studies of volatile processes in the outer solar system are discussed. Researchers suggest that the convective and conductive regions of Triton's atmosphere join at the tropopause near 10 km. A model of volatile transport on Triton's surface was constructed that predicts that Triton's surface north of 15 degrees north latitude is experiencing deposition of nitrogen frosts, as are the bright portions of the south polar cap near the equator. Also discussed are numerical models of the evolution of Titan's surface and atmosphere. Results of a study of the rheology of ammonia-water liquids were applied to the icy satellites of the outer solar system. Finally, the researchers examined the frictional heating, sublimation, and re-condensation of grains free-falling into the solar nebula from a surrounding interstellar cloud. The sublimation model includes the effect of various volatile species and accounts for the poor radiating properties of small grains using Mie theory.

On the structure of solar and stellar coronae - Loops and loop heat transport

NASA Technical Reports Server (NTRS)

Litwin, Christof; Rosner, Robert

1993-01-01

We discuss the principal constraints on mechanisms for structuring and heating the outer atmospheres - the coronae - of stars. We argue that the essential cause of highly localized heating in the coronae of stars like the sun is the spatially intermittent nature of stellar surface magnetic fields, and that the spatial scale of the resulting coronal structures is related to the spatial structure of the photospheric fields. We show that significant constraints on coronal heating mechanisms derive from the observed variations in coronal emission, and, in addition, show that the observed structuring perpendicular to coronal magnetic fields imposes severe constraints on mechanisms for heat dispersal in the low-beta atmosphere. In particular, we find that most of commonly considered mechanisms for heat dispersal, such as anomalous diffusion due to plasma turbulence or magnetic field line stochasticity, are much too slow to account for the observed rapid heating of coronal loops. The most plausible mechanism appears to be reconnection at the interface between two adjacent coronal flux bundles. Based on a model invoking hyperresistivity, we show that such a mechanism naturally leads to dominance of isolated single bright coronal loops and to bright coronal plasma structures whose spatial scale transverse to the local magnetic field is comparable to observed dimensions of coronal X-ray loops.

X-Ray, UV and Optical Observations of Classical Cepheids: New Insights into Cepheid Evolution, and the Heating and Dynamics of Their Atmospheres

NASA Astrophysics Data System (ADS)

Engle, Scott G.; Guinan, Edward F.

2012-06-01

To broaden the understanding of classical Cepheid structure, evolution and atmospheres, we have extended our continuing secret lives of Cepheids program by obtaining XMM/Chandra X-ray observations, and Hubble space telescope (HST) / cosmic origins spectrograph (COS) FUV-UV spectra of the bright, nearby Cepheids Polaris, δ Cep and β Dor. Previous studies made with the international ultraviolet explorer (IUE) showed a limited number of UV emission lines in Cepheids. The well-known problem presented by scattered light contamination in IUE spectra for bright stars, along with the excellent sensitivity & resolution combination offered by HST/COS, motivated this study, and the spectra obtained were much more rich and complex than we had ever anticipated. Numerous emission lines, indicating 10^4 K up to ~3 x 10^5 K plasmas, have been observed, showing Cepheids to have complex, dynamic outer atmospheres that also vary with the photospheric pulsation period. The FUV line emissions peak in the phase range φ ∼ 0.8-1.0 and vary by factors as large as 10x. A more complete picture of Cepheid outer atmospheres is accomplished when the HST/COS results are combined with X-ray observations that we have obtained of the same stars with XMM-Newton & Chandra. The Cepheids detected to date have X-ray luminosities of log Lx ~ 28.5-29.1 ergs/sec, and plasma temperatures in the 2-8 x 10^6 K range. Given the phase-timing of the enhanced emissions, the most plausible explanation is the formation of a pulsation-induced shocks that excite (and heat) the atmospheric plasmas surrounding the photosphere. A pulsation-driven α^2 equivalent dynamo mechanism is also a viable and interesting alternative. However, the tight phase-space of enhanced emission (peaking near 0.8-1.0 φ) favor the shock heating mechanism hypothesis.

Influence of non-Kolmogorov atmospheric turbulence on the beam quality of vortex beams.

PubMed

Li, Jinhong; Wang, Weiwei; Duan, Meiling; Wei, Jinlin

2016-09-05

Based on the extended Huygens-Fresnel principle and the definition of second-order moments of the Wigner distribution function (WDF), the analytical expressions for the propagation factors (M²-factors) and Strehl ratio S_R of the Gaussian Schell-model (GSM) vortex beams and GSM non-vortex beams propagation through non-Kolmogorov atmospheric turbulence are derived, and used to study the influence of non-Kolmogorov atmospheric turbulence on beam quality of the GSM vortex beams. It is shown that the smaller the generalized structure constant and the outer scale of turbulence are, and the bigger the inner scale of turbulence is, the smaller the normalized propagation factor is, the bigger the Strehl ratio is, and the better the beam quality of GSM vortex beams in atmospheric turbulence is. The variation of beam quality with the generalized exponent α is nonmonotonic, when α = 3.11, the beam quality of the GSM vortex beams is the poorest through non-Kolmogorov atmospheric turbulence. GSM vortex beams is less affected by turbulence than GSM non-vortex beams under certain condition, and will be useful in long-distance free-space optical communications.

Atmospheric, Ionospheric, and Energetic Radiation Environments of Saturn's Rings

NASA Astrophysics Data System (ADS)

Cooper, J. F.; Kollmann, P.; Sittler, E. C., Jr.; Johnson, R. E.; Sturner, S. J.

2015-12-01

Planetary magnetospheric and high-energy cosmic ray interactions with Saturn's rings were first explored in-situ during the Pioneer 11 flyby in 1979. The following Voyager flybys produced a wealth of new information on ring structure and mass, and on spatial structure of the radiation belts beyond the main rings. Next came the Cassini Orbiter flyover of the rings during Saturn Orbital Insertion in 2004 with the first in-situ measurements of the ring atmosphere and plasma ionosphere. Cassini has since fully explored the radiation belt and magnetospheric plasma region beyond the main rings, discovering how Enceladus acts as a source of water group neutrals and water ions for the ion plasma. But do the main rings also substantially contribute by UV photolysis to water group plasma (H+, O+, OH+, H2O+, H3O+, O2+) and neutrals inwards from Enceladus? More massive rings, than earlier inferred from Pioneer 11 and Voyager observations, would further contribute by bulk ring ice radiolysis from interactions of galactic cosmic ray particles. Products of these interactions include neutron-decay proton and electron injection into the radiation belts beyond the main rings. How does radiolysis from moon and ring sweeping of the radiation belt particles compare with direct gas and plasma sources from the main rings and Enceladus? Can the magnetospheric ion and electron populations reasonably be accounted for by the sum of the ring-neutron-decay and outer magnetospheric inputs? Pioneer 11 made the deepest radial penetration into the C-ring, next followed by Cassini SOI. What might Cassini's higher-inclination proximal orbits reveal about the atmospheric, ionospheric, and energetic radiation environments in the D-ring and the proximal gap region? Recent modeling predicts a lower-intensity innermost radiation belt extending from the gap to the inner D-ring. Other remaining questions include the lifetimes of narrow and diffuse dust rings with respect to plasma and energetic particle irradiation processes, the mass flux of water group ions along planetary magnetic field lines into the Saturn planetary atmosphere, seasonal dust charging dynamics of the now-reappeared Saturn ring spokes, and the exchange of energy via energetic neutral atoms between the outer magnetosphere and the rings.

Atmospheric entry probes for outer planet exploration. Outer planet entry probe technical summary

NASA Technical Reports Server (NTRS)

1974-01-01

The use of unmanned space probes for investigating the conditions existing on and around the outer planets of the solar system is discussed. The subjects included in the report are: (1) the design of a common entry probe for outer planet missions, (2) the significant trades related to the development of a common probe design, (3) the impact of bus selection on probe design, (4) the impact of probe requirements on bus modifications, and (5) the key technology elements recommended for advanced development. Drawings and illustrations of typical probes are included to show the components and systems used in the space probes.

NASA's Solar Eclipse Composite Image July 11, 2010

NASA Image and Video Library

2017-12-08

Eclipse 2010 Composite A solar eclipse photo (gray and white) from the Williams College Expedition to Easter Island in the South Pacific (July 11, 2010) was embedded with an image of the Sun’s outer corona taken by the Large Angle Spectrometric Coronagraph (LASCO) on the SOHO spacecraft and shown in red false color. LASCO uses a disk to blot out the bright sun and the inner corona so that the faint outer corona can be monitored and studied. Further, the dark silhouette of the moon was covered with an image of the Sun taken in extreme ultraviolet light at about the same time by the Atmospheric Imaging Assembly on Solar Dynamics Observatory (SDO). The composite brings out the correlation of structures in the inner and outer corona. Credits: Williams College Eclipse Expedition -- Jay M. Pasachoff, Muzhou Lu, and Craig Malamut; SOHO’s LASCO image courtesy of NASA/ESA; solar disk image from NASA’s SDO; compositing by Steele Hill, NASA Goddard Space Flight Center. NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Laboratory studies of low temperature rate coefficients: The atmospheric chemistry of the outer planets

NASA Technical Reports Server (NTRS)

Leone, Stephen R.

1992-01-01

The purpose of the project is to perform laboratory measurements of reaction rate coefficients at low temperature. The reactions and temperatures of interest are those that are important in the chemistry of the hydrocarbon rich atmospheres of the outer planets and their satellites. In this stage of the study we are investigating reactions of ethynyl radicals, C2H, with acetylene (C2H2), methane (CH4), and hydrogen (H2). In the previous status report from 24 Jan. 1992, we reported on the development of the experimental apparatus and the first, preliminary data for the C2H + C2H2 reaction.

Studies on possible propagation of microbial contamination in planetary clouds

NASA Technical Reports Server (NTRS)

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

1973-01-01

Current U.S. planetary quarantine standards based on international agreements require consideration of the probability of contamination (Pc) of the outer planets, Venus, Jupiter, Saturn, etc. One of the key parameters in estimation of the Pc of these planets is the probability of growth (Pg) of terrestrial microorganisms on or near these planets. For example, Jupiter and Saturn appear 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 plants.

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.

Definition phase of Grand Tour missions/radio science investigations study for outer planets missions

NASA Technical Reports Server (NTRS)

Tyler, G. L.

1972-01-01

Scientific instrumentation for satellite communication and radio tracking systems in the outer planet exploration mission is discussed. Mission planning considers observations of planetary and satellite-masses, -atmospheres, -magnetic fields, -surfaces, -gravitational fields, solar wind composition, planetary radio emissions, and tests of general relativity in time delay and ray bending experiments.

On the possibility of space objects invasion observations into the Earth's atmosphere with the help of a multifunctional polarimeter

NASA Astrophysics Data System (ADS)

Nevodovskyi, P. V.; Steklov, A. F.; Vidmachenko, A. P.

2018-05-01

Relevance of the tasks associated with the observation of the invasion of space objects into the Earth's atmosphere increases with each passing year. We used astronomical panoramic polarimeter for carrying out of polarimetric observations of objects, that flying into the atmosphere of the Earth from the surrounding outer space.

Observations and modeling of cool, evolved stars: from chromospheric to wind regions

NASA Astrophysics Data System (ADS)

Rau, Gioia; Carpenter, Ken G.; Nielsen, Krister E.; Kober, Gladys V.; Josef Hron, Bernard Aringer, Kjell Eriksson, Paola Marigo, Claudia Paladini

2018-01-01

Evolved stars are fundamental contributors to the enrichment of the interstellar medium, via their mass loss, with heavy elements produced in their interior, and with the dust formed in their envelope. We present the results of the first systematic comparison (Rau et al. 2017, 2015) of multi-technique observations of a sample of C-rich Mira, semi-regular and irregular stars with the predictions from dynamic model atmospheres (Mattsson et al. 2010) and simpler models based on hydrostatic atmospheres combined with dusty envelopes. The chromosphere, located in the outer atmosphere of these stars, plays a crucial role in driving the mass loss in evolved K-M giant stars (see e.g. Carpenter et al. 2014, 1988). Despite recent efforts, details of the mass-loss scenario remain mysterious, as well as a complete understanding of the dynamic line formation regions, profiles, and structures. To solve these riddles, we present observation of flow and turbulent velocities, together with preliminary derivation of thermodynamic constraints for theoretical models (Rau, Carpenter, et al., in prep).

Infrared spectra of molecules and materials of astrophysical interest

NASA Technical Reports Server (NTRS)

Durig, J. R.

1976-01-01

The vibrational spectra from 4,000 to 33/cm of several molecules which may be present in the atmosphere of the Jovian planets or exist in outer space were studied. These studies have been made to provide vibrational frequencies which can be used to: (1) determine the composition of the cloud covers of several of the planets, (2) provide structural information under favorable circumstances, (3) provide necessary data from which accurate thermodynamic data can be calculated, and (4) furnish information as to the nature of the potential energy function of the molecules and forces acting within them. Some of the molecules studied can be produced photochemically from methane, ammonia, and hydrogen sulfide which are thought to be constituents of the planets with reducing atmospheres. Some of the compounds will polymerize under ultraviolet radiation and drop out of the atmospheres. However, planets with a hot base, like that of Jupiter, may rebuild molecules destroyed photochemically. These criteria were used in selecting the compounds under study.

Further analysis of scintillation index for a laser beam propagating through moderate-to-strong non-Kolmogorov turbulence based on generalized effective atmospheric spectral model

NASA Astrophysics Data System (ADS)

Ma, Jing; Fu, Yu-Long; Yu, Si-Yuan; Xie, Xiao-Long; Tan, Li-Ying

2018-03-01

A new expression of the scintillation index (SI) for a Gaussian-beam wave propagating through moderate-to-strong non-Kolmogorov turbulence is derived, using a generalized effective atmospheric spectrum and the extended Rytov approximation theory. Finite inner and outer scale parameters and high wave number “bump” are considered in the spectrum with a generalized spectral power law in the range of 3–4, instead of the fixed classical Kolmogorov power law of 11/3. The obtained SI expression is then used to analyze the effects of the spectral power law and the inner scale and outer scale on SI under various non-Kolmogorov fluctuation conditions. These results will be useful in future investigations of optical wave propagation through atmospheric turbulence.

Haze and cloud distribution in Uranus' atmosphere based on high-contrast spatially resolved polarization measurements

NASA Astrophysics Data System (ADS)

Kostogryz, Nadiia; Berdyugina, Svetlana; Gisler, Daniel; Berkefeld, Thomas

2017-04-01

In planetary atmospheres, main sources of opacity are molecular absorption and scattering on molecules, hazes and aerosols. Hence, light reflected from a planetary atmosphere can be linearly polarized. Polarization study of inner solar system planets and exoplanets is a powerful method to characterize their atmospheres, because of a wide range of observable phase angles. For outer solar system planets, observable phase angles are very limited. For instance, Uranus can only be observed up to 3.2 degrees away from conjunctions, and its disk-integrated polarization is close to zero due to the back-scattering geometry. However, resolving the disk of Uranus and measuring the center-to-limb polarization can help constraining the vertical atmospheric structure and the nature of scattering aerosols and particles. In October 2016, we carried out polarization measurements of Uranus in narrow-band filters centered at methane bands and the adjacent continuum using the GREGOR Planet Polarimeter (GPP). The GPP is a high-precision polarimeter and is mounted at the 1.5-m GREGOR solar telescope, which is suitable for observing at night. In order to reach a high spatial resolution, the instrument uses an adaptive-optics system of the telescope. To interpret our measurements, we solve the polarized radiative transfer problem taking into account different scattering and absorption opacities. We calculate the center-to-limb variation of polarization of Uranus' disk in the continuum spectrum and in methane bands. By varying the vertical distribution of haze and cloud layers, we derive the vertical structure of the best-fit Uranus atmosphere.

Global 3D radiation-hydrodynamics models of AGB stars. Effects of convection and radial pulsations on atmospheric structures

NASA Astrophysics Data System (ADS)

Freytag, B.; Liljegren, S.; Höfner, S.

2017-04-01

Context. Observations of asymptotic giant branch (AGB) stars with increasing spatial resolution reveal new layers of complexity of atmospheric processes on a variety of scales. Aims: To analyze the physical mechanisms that cause asymmetries and surface structures in observed images, we use detailed 3D dynamical simulations of AGB stars; these simulations self-consistently describe convection and pulsations. Methods: We used the CO5BOLD radiation-hydrodynamics code to produce an exploratory grid of global "star-in-a-box" models of the outer convective envelope and the inner atmosphere of AGB stars to study convection, pulsations, and shock waves and their dependence on stellar and numerical parameters. Results: The model dynamics are governed by the interaction of long-lasting giant convection cells, short-lived surface granules, and strong, radial, fundamental-mode pulsations. Radial pulsations and shorter wavelength, traveling, acoustic waves induce shocks on various scales in the atmosphere. Convection, waves, and shocks all contribute to the dynamical pressure and, thus, to an increase of the stellar radius and to a levitation of material into layers where dust can form. Consequently, the resulting relation of pulsation period and stellar radius is shifted toward larger radii compared to that of non-linear 1D models. The dependence of pulsation period on luminosity agrees well with observed relations. The interaction of the pulsation mode with the non-stationary convective flow causes occasional amplitude changes and phase shifts. The regularity of the pulsations decreases with decreasing gravity as the relative size of convection cells increases. The model stars do not have a well-defined surface. Instead, the light is emitted from a very extended inhomogeneous atmosphere with a complex dynamic pattern of high-contrast features. Conclusions: Our models self-consistently describe convection, convectively generated acoustic noise, fundamental-mode radial pulsations, and atmospheric shocks of various scales, which give rise to complex changing structures in the atmospheres of AGB stars.

The variance of angle-of-arrival fluctuation of partially coherent Gaussian-Schell Model beam propagations in slant atmospheric turbulence

NASA Astrophysics Data System (ADS)

Tan, Zhenkun; Ke, Xizheng

2017-10-01

The variance of angle-of-arrival fluctuation of the partially coherent Gaussian-Schell Model (GSM) beam propagations in the slant path, based on the extended Huygens-Fresnel principle and the model of atmospheric refraction index structural constant proposed by the international telecommunication union-radio (ITU-R), has been investigated under the modified Hill turbulence model. The expression of that has been obtained. Firstly, the effects of optical wavelength, the inner-and-outer scale of the turbulence and turbulence intensity on the variance of angle-of-arrival fluctuation have been analyzed by comparing with the partially coherent GSM beam and the completely coherent Gaussian beam. Secondly, the variance of angle-of-arrival fluctuation has been compared with the von Karman spectrum and the modified Hill spectrum under the partially coherent GSM beam. Finally, the effects of beam waist radius and partial coherence length on the variance of angle-of-arrival of the collimated (focused) beam have been analyzed under the modified Hill turbulence model. The results show that the influence of the variance of angle-of-arrival fluctuation for the inner scale effect is larger than that of the outer scale effect. The variance of angle-of-arrival fluctuation under the modified Hill spectrum is larger than that of the von Karman spectrum. The influence of the waist radius on the variance of angle-of-arrival for the collimated beam is less than focused the beam. This study will provide a necessary theoretical basis for the experiments of partially coherent GSM beam propagation through atmosphere turbulence.

Overview of the Mars Sample Return Earth Entry Vehicle

NASA Technical Reports Server (NTRS)

Dillman, Robert; Corliss, James

2008-01-01

NASA's Mars Sample Return (MSR) project will bring Mars surface and atmosphere samples back to Earth for detailed examination. Langley Research Center's MSR Earth Entry Vehicle (EEV) is a core part of the mission, protecting the sample container during atmospheric entry, descent, and landing. Planetary protection requirements demand a higher reliability from the EEV than for any previous planetary entry vehicle. An overview of the EEV design and preliminary analysis is presented, with a follow-on discussion of recommended future design trade studies to be performed over the next several years in support of an MSR launch in 2018 or 2020. Planned topics include vehicle size for impact protection of a range of sample container sizes, outer mold line changes to achieve surface sterilization during re-entry, micrometeoroid protection, aerodynamic stability, thermal protection, and structural materials selection.

New Insights in the Long-Term Atmospheric Corrosion Mechanisms of Low Alloy Steel Reinforcements of Cultural Heritage Buildings

PubMed Central

Bouchar, Marie; Dillmann, Philippe; Neff, Delphine

2017-01-01

Reinforcing clamps made of low alloy steel from the Metz cathedral and corroded outdoors during 500 years were studied by OM, FESEM/EDS, and micro-Raman spectroscopy. The corrosion product layer is constituted of a dual structure. The outer layer is mainly constituted of goethite and lepidocrocite embedding exogenous elements such as Ca and P. The inner layer is mainly constituted of ferrihydrite. The behaviour of the inner layer under conditions simulating the wetting stage of the RH wet/dry atmospheric corrosion cycle was observed by in situ micro-Raman spectroscopy. The disappearance of ferrihydrite near the metal/oxide interface strongly suggests a mechanism of reductive dissolution caused by the oxidation of the metallic substrate and was observed for the first time in situ on an archaeological system. PMID:28773030

PVOL: The Planetary Virtual Observatory & Laboratory. An online database of the Outer Planets images.

NASA Astrophysics Data System (ADS)

Morgado, A.; Sánchez-Lavega, A.; Rojas, J. F.; Hueso, R.

2005-08-01

The collaboration between amateurs astronomers and the professional community has been fruitful on many areas of astronomy. The development of the Internet has allowed a better than ever capability of sharing information worldwide and access to other observers data. For many years now the International Jupiter Watch (IJW) Atmospheric discipline has coordinated observational efforts for long-term studies of the atmosphere of Jupiter. The International Outer Planets Watch (IOPW) has extended its labours to the four Outer Planets. Here we present the Planetary Virtual Observatory & Laboratory (PVOL), a website database where we integer IJW and IOPW images. At PVOL observers can submit their data and professionals can search for images under a wide variety of useful criteria such as date and time, filters used, observer, or central meridian longitude. PVOL is aimed to grow as an organized easy to use database of amateur images of the Outer Planets. The PVOL web address is located at http://www.pvol.ehu.es/ and coexists with the traditional IOPW site: http://www.ehu.es/iopw/ Acknowledgements: This work has been funded by Spanish MCYT PNAYA2003-03216, fondos FEDER and Grupos UPV 15946/2004. R. Hueso acknowledges a post-doc fellowship from Gobierno Vasco.

Self-sterilization of bodies during outer planet entry

NASA Technical Reports Server (NTRS)

Hoffman, A. R.; Jaworski, W.; Taylor, D. M.

1974-01-01

A body encountering the atmosphere of an outer planet is subjected to heat loads which could result in high temperature conditions that render terrestrial organisms on or within the body nonviable. To determine whether an irregularly shaped entering body, consisting of several different materials, would be sterilized during inadvertent entry at high velocity, the thermal response of a typical outer planet spacecraft instrument was studied. The results indicate that the Teflon insulated cable and electronic circuit boards may not experience sterilizing temperatures during a Jupiter, Saturn, or Titan entry. Another conclusion of the study is that small plastic particles entering Saturn from outer space have wider survival corridors than do those at Jupiter.

(abstract) A Low-Cost Mission to 2060 Chiron Based on the Pluto Fast Flyby

NASA Technical Reports Server (NTRS)

Stern, S. A.; Salvo, C. G.; Wallace, R. A.; Weinstein, S. S.; Weissman, P. R.

1994-01-01

The Pluto Fast Flyby-based mission to Chiron described in this paper is a low cost, scientifically rewarding, focused mission in the outer solar system. The proposed mission will make a flyby of 2060 Chiron, an active 'comet' with over 10(sup 4) times the mass of Halley, and an eccentric, Saturn-crossing orbit which ranges from 8.5 to 19 AU. This mission concept achieves the flyby 4.2 years after launch on a direct trajectory from Earth, is independent of Jupiter launch windows, and fits within Discovery cost guidelines. This mission offers the scientific opportunity to examine a class of object left unsampled by the trail-blazing Mariners, Pioneers, Voyagers, and missions to Halley. Spacecraft reconnaissance of Chiron addresses unique objectives relating to cometary science, other small bodies, the structure of quasi-bound atmospheres on modest-sized bodies, and the origin of primitive bodies and the giant planets. Owing to Chiron's large size (180

Simulation of the Processes of Formation of a Dust Cloud in a Vacuum and in the Absence of Gravitation

NASA Astrophysics Data System (ADS)

Avdeev, A. V.; Boreisho, A. S.; Ivakin, S. V.; Moiseev, A. A.; Savin, A. V.; Sokolov, E. I.; Smirnov, P. G.

2018-01-01

This article is devoted to the simulation of the processes of formation of dust clouds in the absence of gravitation, which is necessary for understanding the processes proceeding in dust clusters in outer space, upper planetary atmosphere, and on the surface of space objects, as well as for evaluating the possibilities of creating disperse structures with given properties. The chief aim of the simulation is to determine the general laws of the dynamics of the dust cloud at the initial stage of its formation. With the use of the original approach based on the particle-in-cell method that permits investigating the mechanics of large ensembles of particles on contemporary computational platforms, we consider the mechanics of a dusty medium in the process of its excitation in a closed container due to the vibration of the walls, and then in the process of particle scattering when the container opens in outer space. The main formation mechanisms of a dust formation have been elucidated, and the possibilities of mathematical simulation for predicting spatial and time characteristics of disperse structures have been shown.

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

Maniwa, Yutaka; Fujiwara, Ryuji; Kira, Hiroshi

X-ray diffraction study of multiwalled carbon nanotube (MWNT) grown by arc discharge in hydrogen atmosphere is presented. It is found that the thermal-expansion coefficient along the radial direction of MWNT is widely distributed in a range from 1.6 x 10{sup -5} K{sup -1} to 2.6 x 10{sup -5} K{sup -1}, indicating the existence of both of Russian doll MWNT and highly defective MWNT. Russian doll MWNT is suggested to have the outer diameter less than {approx}100 Aa. Thicker MWNT's are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains.

Global Magnetohydrodynamic Modeling of the Solar Corona

NASA Technical Reports Server (NTRS)

Linker, Jon A.; Wagner, William (Technical Monitor)

2001-01-01

The solar corona, the hot, tenuous outer atmosphere of the Sun, exhibits many fascinating phenomena on a wide range of scales. One of the ways that the Sun can affect us here at Earth is through the large-scale structure of the corona and the dynamical phenomena associated with it, as it is the corona that extends outward as the solar wind and encounters the Earth's magnetosphere. The goal of our research sponsored by NASA's Supporting Research and Technology Program in Solar Physics is to develop increasingly realistic models of the large-scale solar corona, so that we can understand the underlying properties of the coronal magnetic field that lead to the observed structure and evolution of the corona. We describe the work performed under this contract.

Vadose zone isobaric well

DOEpatents

Hubbell, Joel M.; Sisson, James B.

2001-01-01

A deep tensiometer is configured with an outer guide tube having a vented interval along a perforate section at its lower end, which is isolated from atmospheric pressure at or above grade. A transducer having a monitoring port and a reference port is located within a coaxial inner guide tube. The reference port of the transducer is open to the vented interval of the outer guide tube, which has the same gas pressure as in the sediment surrounding the tensiometer. The reference side of the pressure transducer is thus isolated from the effects of atmospheric pressure changes and relative to pressure changes in the material surrounding the tensiometer measurement location and so it is automatically compensated for such pressure changes.

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

Semi-empirical models of the wind in cool supergiant stars

NASA Technical Reports Server (NTRS)

Kuin, N. P. M.; Ahmad, Imad A.

1988-01-01

A self-consistent semi-empirical model for the wind of the supergiant in zeta Aurigae type systems is proposed. The damping of the Alfven waves which are assumed to drive the wind is derived from the observed velocity profile. Solution of the ionization balance and energy equation gives the temperature structure for given stellar magnetic field and wave flux. Physically acceptable solutions of the temperature structure place limits on the stellar magnetic field. A crude formula for a critical mass loss rate is derived. For a mass loss rate below the critical value the wind cannot be cool. Comparison between the observed and the critical mass loss rate suggests that the proposed theory may provide an explanation for the coronal dividing line in the Hertzsprung-Russell diagram. The physical explanation may be that the atmosphere has a cool wind, unless it is physically impossible to have one. Stars which cannot have a cool wind release their nonthermal energy in an outer atmosphere at coronal temperatures. It is possible that in the absence of a substantial stellar wind the magnetic field has less incentive to extend radially outward, and coronal loop structures may become more dominant.

Apparatus for integrating a rigid structure into a flexible wall of an inflatable structure

NASA Technical Reports Server (NTRS)

Johnson, Christopher J. (Inventor); Patterson, Ross M. (Inventor); Spexarth, Gary R. (Inventor)

2009-01-01

For an inflatable structure having a flexible outer shell or wall structure having a flexible restraint layer comprising interwoven, load-bearing straps, apparatus for integrating one or more substantially rigid members into the flexible shell. For each rigid member, a corresponding opening is formed through the flexible shell for receiving the rigid member. A plurality of connection devices are mounted on the rigid member for receiving respective ones of the load-bearing straps. In one embodiment, the connection devices comprise inner connecting mechanisms and outer connecting mechanisms, the inner and outer connecting mechanisms being mounted on the substantially rigid structure and spaced along a peripheral edge portion of the structure in an interleafed array in which respective outer connecting mechanisms are interposed between adjacent pairs of inner connecting mechanisms, the outer connecting mechanisms projecting outwardly from the peripheral edge portion of the substantially rigid structure beyond the adjacent inner connecting mechanisms to form a staggered array of connecting mechanisms extending along the panel structure edge portion. In one embodiment, the inner and outer connecting mechanisms form part of an integrated, structure rotatably mounted on the rigid member peripheral edge portion.

Flow rate measurement in a volume

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

Galvez, Cristhian

A system for measuring flow rate within a volume includes one or more transmission devices that transmit one or more signals through fluid contained within the volume. The volume may be bounded, at least in part, by an outer structure and by an object at least partially contained within the outer structure. A transmission device located at a first location of the outer structure transmits a first signal to a second location of the outer structure. A second signal is transmitted through the fluid from the second location to a third location of the outer structure. The flow rate ofmore » the fluid within the volume may be determined based, at least in part, on the time of flight of both the first signal and the second signal.« less

Jet formation and equatorial superrotation in Jupiter's atmosphere: Numerical modelling using a new efficient parallel code

NASA Astrophysics Data System (ADS)

Rivier, Leonard Gilles

Using an efficient parallel code solving the primitive equations of atmospheric dynamics, the jet structure of a Jupiter like atmosphere is modeled. In the first part of this thesis, a parallel spectral code solving both the shallow water equations and the multi-level primitive equations of atmospheric dynamics is built. The implementation of this code called BOB is done so that it runs effectively on an inexpensive cluster of workstations. A one dimensional decomposition and transposition method insuring load balancing among processes is used. The Legendre transform is cache-blocked. A "compute on the fly" of the Legendre polynomials used in the spectral method produces a lower memory footprint and enables high resolution runs on relatively small memory machines. Performance studies are done using a cluster of workstations located at the National Center for Atmospheric Research (NCAR). BOB performances are compared to the parallel benchmark code PSTSWM and the dynamical core of NCAR's CCM3.6.6. In both cases, the comparison favors BOB. In the second part of this thesis, the primitive equation version of the code described in part I is used to study the formation of organized zonal jets and equatorial superrotation in a planetary atmosphere where the parameters are chosen to best model the upper atmosphere of Jupiter. Two levels are used in the vertical and only large scale forcing is present. The model is forced towards a baroclinically unstable flow, so that eddies are generated by baroclinic instability. We consider several types of forcing, acting on either the temperature or the momentum field. We show that only under very specific parametric conditions, zonally elongated structures form and persist resembling the jet structure observed near the cloud level top (1 bar) on Jupiter. We also study the effect of an equatorial heat source, meant to be a crude representation of the effect of the deep convective planetary interior onto the outer atmospheric layer. We show that such heat forcing is able to produce strong equatorial superrotating winds, one of the most striking feature of the Jovian circulation.

The solar system/interstellar medium connection - Gas phase abundances

NASA Technical Reports Server (NTRS)

Lutz, Barry L.

1987-01-01

Gas-phase abundances in the outer solar system are presented as diagnostics of the interstellar medium at the time of the solar system formation, some 4.55 billion years ago. Possible influences of the thermal and chemical histories of the primitive solar nebula and of the processes which led to the formation and evolution of the outer planets and comets on the elemental and molecular composition of the primordial matter are outlined. The major components of the atmospheres of the outer planets and of the comae of comets are identified, and the cosmogonical and cosmological implications are discussed.

Outer planet probe cost estimates: First impressions

NASA Technical Reports Server (NTRS)

Niehoff, J.

1974-01-01

An examination was made of early estimates of outer planetary atmospheric probe cost by comparing the estimates with past planetary projects. Of particular interest is identification of project elements which are likely cost drivers for future probe missions. Data are divided into two parts: first, the description of a cost model developed by SAI for the Planetary Programs Office of NASA, and second, use of this model and its data base to evaluate estimates of probe costs. Several observations are offered in conclusion regarding the credibility of current estimates and specific areas of the outer planet probe concept most vulnerable to cost escalation.

A photometric mode identification method, including an improved non-adiabatic treatment of the atmosphere

NASA Astrophysics Data System (ADS)

Dupret, M.-A.; De Ridder, J.; De Cat, P.; Aerts, C.; Scuflaire, R.; Noels, A.; Thoul, A.

2003-02-01

We present an improved version of the method of photometric mode identification of Heynderickx et al. (\\cite{hey}). Our new version is based on the inclusion of precise non-adiabatic eigenfunctions determined in the outer stellar atmosphere according to the formalism recently proposed by Dupret et al. (\\cite{dup}). Our improved photometric mode identification technique is therefore no longer dependent on ad hoc parameters for the non-adiabatic effects. It contains the complete physical conditions of the outer atmosphere of the star, provided that rotation does not play a key role. We apply our method to the two slowly pulsating B stars HD 74560 and HD 138764 and to the beta Cephei star EN (16) Lac. Besides identifying the degree l of the pulsating stars, our method is also a tool for improving the knowledge of stellar interiors and atmospheres, by imposing constraints on parameters such as the metallicity and the mixing-length parameter alpha (a procedure we label non-adiabatic asteroseismology). The non-adiabatic eigenfunctions needed for the mode identification are available upon request from the authors.

Definition of a metrology servo-system for a solar imaging fourier transform spectrometer working in the far UV (IFTSUV)

NASA Astrophysics Data System (ADS)

Ruiz de Galarreta Fanju, C.; Philippon, A.; Bouzit, M.; Appourchaux, T.; Vial, J.-C.; Maillard, J.-P.; Lemaire, P.

2017-11-01

The understanding of the solar outer atmosphere requires a simultaneous combination of imaging and spectral observations concerning the far UV lines that arise from the high chromospheres up to the corona. These observations must be performed with enough spectral, spatial and temporal resolution to reveal the small atmospheric structures and to resolve the solar dynamics. An Imaging Fourier Transform Spectrometer working in the far-UV (IFTSUV, Figure 1) is an attractive instrumental solution to fulfill these requirements. However, due to the short wavelength, to preserve IFTSUV spectral precision and Signal to Noise Ratio (SNR) requires a high optical surface quality and a very accurate (linear and angular) metrology to maintain the optical path difference (OPD) during the entire scanning process by: optical path difference sampling trigger; and dynamic alignment for tip/tilt compensation (Figure 2).

Ultra-fine-scale filamentary structures in the Outer Corona and the Solar Magnetic Field

NASA Technical Reports Server (NTRS)

Woo, Richard

2006-01-01

Filamentary structures following magnetic field lines pervade the Sun's atmosphere and offer us insight into the solar magnetic field. Radio propagation measurements have shown that the smallest filamentary structures in the solar corona are more than 2 orders of magnitude finer than those seen in solar imaging. Here we use radio Doppler measurements to characterize their transverse density gradient and determine their finest scale in the outer corona at 20-30 R(circled dot operator), where open magnetic fields prevail. Filamentary structures overly active regions have the steepest gradient and finest scale, while those overlying coronal holes have the shallowest gradient and least finest scale. Their organization by the underlying corona implies that these subresolution structures extend radially from the entire Sun, confirming that they trace the coronal magnetic field responsible for the radial expansion of the solar wind. That they are rooted all over the Sun elucidates the association between the magnetic field of the photosphere and that of the corona, as revealed by the similarity between the power spectra of the photospheric field and the coronal density fluctuations. This association along with the persistence of filamentary structures far from the Sun demonstrate that subresolution magnetic fields must play an important role not only in magnetic coupling of the photosphere and corona, but also in coronal heating and solar wind acceleration through the process of small-scale magnetic reconnection. They also explain why current widely used theoretical models that extrapolate photospheric magnetic fields into the corona do not predict the correct source of the solar wind.

Rapid Loss of Radiation Belt Relativistic Electrons by EMIC Waves

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

Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan

How relativistic electrons are lost is an important question surrounding the complex dynamics of the Earth's outer radiation belt. Radial loss to the magnetopause and local loss to the atmosphere are two main competing paradigms. Here on the basis of the analysis of a radiation belt storm event on 27 February 2014, we present new evidence for the electromagnetic ion cyclotron (EMIC) wave-driven local precipitation loss of relativistic electrons in the heart of the outer radiation belt. During the main phase of this storm, the radial profile of relativistic electron phase space density was quasi-monotonic, qualitatively inconsistent with the predictionmore » of radial loss theory. The local loss at low L shells was required to prevent the development of phase space density peak resulting from the radial loss process at high L shells. The rapid loss of relativistic electrons in the heart of outer radiation belt was observed as a dip structure of the electron flux temporal profile closely related to intense EMIC waves. Our simulations further confirm that the observed EMIC waves within a quite limited longitudinal region were able to reduce the off-equatorially mirroring relativistic electron fluxes by up to 2 orders of magnitude within about 1.5 h.« less

Rapid Loss of Radiation Belt Relativistic Electrons by EMIC Waves

DOE PAGES

Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan; ...

2017-08-31

How relativistic electrons are lost is an important question surrounding the complex dynamics of the Earth's outer radiation belt. Radial loss to the magnetopause and local loss to the atmosphere are two main competing paradigms. Here on the basis of the analysis of a radiation belt storm event on 27 February 2014, we present new evidence for the electromagnetic ion cyclotron (EMIC) wave-driven local precipitation loss of relativistic electrons in the heart of the outer radiation belt. During the main phase of this storm, the radial profile of relativistic electron phase space density was quasi-monotonic, qualitatively inconsistent with the predictionmore » of radial loss theory. The local loss at low L shells was required to prevent the development of phase space density peak resulting from the radial loss process at high L shells. The rapid loss of relativistic electrons in the heart of outer radiation belt was observed as a dip structure of the electron flux temporal profile closely related to intense EMIC waves. Our simulations further confirm that the observed EMIC waves within a quite limited longitudinal region were able to reduce the off-equatorially mirroring relativistic electron fluxes by up to 2 orders of magnitude within about 1.5 h.« less

Turbine nozzle/nozzle support structure

DOEpatents

Boyd, Gary L.; Shaffer, James E.

1997-01-01

An axial flow turbine's nozzle/nozzle support structure having a cantilevered nozzle outer structure including an outer shroud and airfoil vanes extending radially inwardly therefrom, an inner shroud radially adjacent the inner end of the airfoil vanes and cooperatively disposed relative to the outer shroud to provide an annular fluid flow path, an inner and an outer support ring respectively arranged radially inside the inner shroud and axially adjacent a portion of the outer shroud, and pins extending through such portion and into the outer support ring. The inner support ring or inner shroud has a groove therein bounded by end walls for receiving and being axially abuttable with a locating projection from the adjacent airfoil vane, inner shroud, or inner support ring. The nozzle outer structure may comprise segments each of which has a single protrusion which is axially engageable with the outer support ring or, alternatively, a first and second protrusion which are arcuately and axially separated and which include axial openings therein whereby first and second protrusions on respective, arcuately adjacent nozzle segments have axial openings therein which are alignable with connector openings in the outer support ring and within each of such aligned openings a pin is receivable. The inner shroud may, likewise, comprise segments which, when assembled in operating configuration, have a 360 degree expanse.

Turbine nozzle/nozzle support structure

DOEpatents

Boyd, G.L.; Shaffer, J.E.

1997-01-07

An axial flow turbine`s nozzle/nozzle support structure is described having a cantilevered nozzle outer structure including an outer shroud and airfoil vanes extending radially inwardly therefrom, an inner shroud radially adjacent the inner end of the airfoil vanes and cooperatively disposed relative to the outer shroud to provide an annular fluid flow path, an inner and an outer support ring respectively arranged radially inside the inner shroud and axially adjacent a portion of the outer shroud, and pins extending through such portion and into the outer support ring. The inner support ring or inner shroud has a groove therein bounded by end walls for receiving and being axially abuttable with a locating projection from the adjacent airfoil vane, inner shroud, or inner support ring. The nozzle outer structure may comprise segments each of which has a single protrusion which is axially engageable with the outer support ring or, alternatively, a first and second protrusion which are arcuately and axially separated and which include axial openings therein whereby first and second protrusions on respective, arcuately adjacent nozzle segments have axial openings therein which are alignable with connector openings in the outer support ring and within each of such aligned openings a pin is receivable. The inner shroud may, likewise, comprise segments which, when assembled in operating configuration, have a 360 degree expanse. 6 figs.

Turbine nozzle/nozzle support structure

DOEpatents

Boyd, Gary L.; Shaffer, James E.

1996-01-01

An axial flow turbine's nozzle/nozzle support structure having a cantilevered nozzle outer structure including an outer shroud and airfoil vanes extending radially inwardly therefrom, an inner shroud radially adjacent the inner end of the airfoil vanes and cooperatively disposed relative to the outer shroud to provide an annular fluid flow path, an inner and an outer support ring respectively arranged radially inside the inner shroud and axially adjacent a portion of the outer shroud, and pins extending through such portion and into the outer support ring. The inner support ring or inner shroud has a groove therein bounded by end walls for receiving and being axially abuttable with a locating projection from the adjacent airfoil vane, inner shroud, or inner support ring. The nozzle outer structure may comprise segments each of which has a single protrusion which is axially engageable with the outer support ring or, alternatively, a first and second protrusion which are arcuately and axially separated and which include axial openings therein whereby first and second protrusions on respective, arcuately adjacent nozzle segments have axial openings therein which are alignable with connector openings in the outer support ring and within each of such aligned openings a pin is receivable. The inner shroud may, likewise, comprise segments which, when assembled in operating configuration, have a 360 degree expanse.

Turbine nozzle/nozzle support structure

DOEpatents

Boyd, G.L.; Shaffer, J.E.

1996-09-10

An axial flow turbine`s nozzle/nozzle support structure is described having a cantilevered nozzle outer structure including an outer shroud and airfoil vanes extending radially inwardly therefrom, an inner shroud radially adjacent the inner end of the airfoil vanes and cooperatively disposed relative to the outer shroud to provide an annular fluid flow path, an inner and an outer support ring respectively arranged radially inside the inner shroud and axially adjacent a portion of the outer shroud, and pins extending through such portion and into the outer support ring. The inner support ring or inner shroud has a groove therein bounded by end walls for receiving and being axially abuttable with a locating projection from the adjacent airfoil vane, inner shroud, or inner support ring. The nozzle outer structure may comprise segments each of which has a single protrusion which is axially engageable with the outer support ring or, alternatively, a first and second protrusion which are arcuately and axially separated and which include axial openings therein whereby first and second protrusions on respective, arcuately adjacent nozzle segments have axial openings therein which are alignable with connector openings in the outer support ring and within each of such aligned openings a pin is receivable. The inner shroud may, likewise, comprise segments which, when assembled in operating configuration, have a 360 degree expanse. 6 figs.

Turbine nozzle/nozzle support structure

DOEpatents

Boyd, Gary L.; Shaffer, James E.

1995-01-01

An axial flow turbine's nozzle/nozzle support structure having a cantilevered nozzle outer structure including an outer shroud and airfoil vanes extending radially inwardly therefrom, an inner shroud radially adjacent the inner end of the airfoil vanes and cooperatively disposed relative to the outer shroud to provide an annular fluid flow path, an inner and an outer support ring respectively arranged radially inside the inner shroud and axially adjacent a portion of the outer shroud, and pins extending through such portion and into the outer support ring. The inner support ring or inner shroud has a groove therein bounded by end walls for receiving and being axially abuttable with a locating projection from the adjacent airfoil vane, inner shroud, or inner support ring. The nozzle outer structure may comprise segments each of which has a single protrusion which is axially engageable with the outer support ring or, alternatively, a first and second protrusion which are arcuately and axially separated and which include axial openings therein whereby first and second protrusions on respective, arcuately adjacent nozzle segments have axial openings therein which are alignable with connector openings in the outer support ring and within each of such aligned openings a pin is receivable. The inner shroud may, likewise, comprise segments which, when assembled in operating configuration, have a 360 degree expanse.

Turbine nozzle/nozzle support structure

DOEpatents

Boyd, G.L.; Shaffer, J.E.

1995-08-15

An axial flow turbine`s nozzle/nozzle support structure is described having a cantilevered nozzle outer structure including an outer shroud and airfoil vanes extending radially inwardly therefrom, an inner shroud radially adjacent the inner end of the airfoil vanes and cooperatively disposed relative to the outer shroud to provide an annular fluid flow path, an inner and an outer support ring respectively arranged radially inside the inner shroud and axially adjacent a portion of the outer shroud, and pins extending through such portion and into the outer support ring. The inner support ring or inner shroud has a groove therein bounded by end walls for receiving and being axially abuttable with a locating projection from the adjacent airfoil vane, inner shroud, or inner support ring. The nozzle outer structure may comprise segments each of which has a single protrusion which is axially engageable with the outer support ring or, alternatively, a first and second protrusion which are arcuately and axially separated and which include axial openings therein whereby first and second protrusions on respective, arcuately adjacent nozzle segments have axial openings therein which are alignable with connector openings in the outer support ring and within each of such aligned openings a pin is receivable. The inner shroud may, likewise, comprise segments which, when assembled in operating configuration, have a 360 degree expanse. 6 figs.

Long-life mission reliability for outer planet atmospheric entry probes

NASA Technical Reports Server (NTRS)

Mccall, M. T.; Rouch, L.; Maycock, J. N.

1976-01-01

The results of a literature analysis on the effects of prolonged exposure to deep space environment on the properties of outer planet atmospheric entry probe components are presented. Materials considered included elastomers and plastics, pyrotechnic devices, thermal control components, metal springs and electronic components. The rates of degradation of each component were determined and extrapolation techniques were used to predict the effects of exposure for up to eight years to deep space. Pyrotechnic devices were aged under accelerated conditions to an equivalent of eight years in space and functionally tested. Results of the literature analysis of the selected components and testing of the devices indicated that no severe degradation should be expected during an eight year space mission.

Electric discharge for treatment of trace contaminants

NASA Technical Reports Server (NTRS)

Flamm, D. L.; Wydeven, T. J. (Inventor)

1978-01-01

A radio frequency glow discharge reactor is described for removing trace oxidizable contaminants from an oxygen bearing atmosphere. The reaction chamber is defined by an inner metal electrode facing a dielectric backed by an outer conductive electrode. In one embodiment, a conductive liquid forms the conductor of an outer electrode and cools the dielectric. A resonator coupled to a variable radio frequency source generates the high voltages for creating a glow discharge in the chamber at a predetermined pressure whereby the trace contaminants are oxidized into a few simple non-toxic products that may be easily recovered. The corresponding process for removal of trace contaminants from an oxygen-bearing atmosphere with high efficiency independent of the concentration level is also disclosed.

TPS for Outer Planets

NASA Technical Reports Server (NTRS)

Venkatapathy, Ethiraj; Ellerby, D.; Gage, P.; Gasch, M.; Hwang, H.; Prabhu, D.; Stackpoole, M.; Wercinski, Paul

2018-01-01

This invited talk will provide an assessment of the TPS needs for Outer Planet In-situ missions to destinations with atmosphere. The talk will outline the drivers for TPS from destination, science, mission architecture and entry environment. An assessment of the readiness of the TPS, both currently available and under development, for Saturn, Titan, Uranus and Neptune are provided. The challenges related to sustainability of the TPS for future missions are discussed.

A Fragment-Cloud Approach for Modeling Atmospheric Breakup of Asteroids with Varied Internal Structures

NASA Astrophysics Data System (ADS)

Wheeler, Lorien; Mathias, Donovan; NASA Engineering Risk Assessment Team, NASA Asteroid Threat Assessment Project

2016-10-01

As an asteroid descends toward Earth, it deposits energy in the atmosphere through aerodynamic drag and ablation. Asteroid impact risk assessments rely on energy deposition estimates to predict blast overpressures and ground damage that may result from an airburst, such as the one that occurred over Chelyabinsk, Russia in 2013. The rates and altitudes at which energy is deposited along the entry trajectory depend upon how the bolide fragments, which in turn depends upon its internal structure and composition. In this work, an analytic asteroid fragmentation model has been developed to model the atmospheric breakup and resulting energy deposition of asteroids with a range of internal structures. The modeling approach combines successive fragmentation of larger independent pieces with aggregate debris clouds released with each fragmentation event. The model can vary the number and masses of fragments produced, the amount of mass released as debris clouds, and the size-strength scaling used to increase the robustness of smaller fragments. The initial asteroid body can be seeded with a distribution of independent fragment sizes amid a remaining debris mass to represent loose rubble pile conglomerations, or can be defined as a monolith with an outer regolith layer. This approach enables the model to represent a range of breakup behaviors and reproduce detailed energy deposition features such as multiple flares due to successive burst events, high-altitude regolith blow-off, or initial disruption of rubble piles followed by more energetic breakup of the constituent boulders. These capabilities provide a means to investigate sensitivities of ground damage to potential variations in asteroid structure.

Spherical Cryogenic Hydrogen Tank Preliminary Design Trade Studies

NASA Technical Reports Server (NTRS)

Arnold, Steven M.; Bednarcyk, Brett A.; Collier, Craig S.; Yarrington, Phillip W.

2007-01-01

A structural analysis, sizing optimization, and weight prediction study was performed by Collier Research Corporation and NASA Glenn on a spherical cryogenic hydrogen tank. The tank consisted of an inner and outer wall separated by a vacuum for thermal insulation purposes. HyperSizer (Collier Research and Development Corporation), a commercial automated structural analysis and sizing software package was used to design the lightest feasible tank for a given overall size and thermomechanical loading environment. Weight trade studies were completed for different panel concepts and metallic and composite material systems. Extensive failure analyses were performed for each combination of dimensional variables, materials, and layups to establish the structural integrity of tank designs. Detailed stress and strain fields were computed from operational temperature changes and pressure loads. The inner tank wall is sized by the resulting biaxial tensile stresses which cause it to be strength driven, and leads to an optimum panel concept that need not be stiffened. Conversely, the outer tank wall is sized by a biaxial compressive stress field, induced by the pressure differential between atmospheric pressure and the vacuum between the tanks, thereby causing the design to be stability driven and thus stiffened to prevent buckling. Induced thermal stresses become a major sizing driver when a composite or hybrid composite/metallic material systems are used for the inner tank wall for purposes such as liners to contain the fuel and reduce hydrogen permeation.

Heavy metals in bark of Pinus massoniana (Lamb.) as an indicator of atmospheric deposition near a smeltery at Qujiang, China.

PubMed

Kuang, Yuan Wen; Zhou, Guo Yi; Da Wen, Zhi; Liu, Shi Zhong

2007-06-01

Rapid urbanization and the expansion of industrial activities in the past several decades have led to large increases in emissions of pollutants in the Pearl River Delta of south China. Recent reports have suggested that industrial emission is a major factor contributing to the damages in current natural ecosystem in the Delta area. Tree barks have been used successfully to monitor the levels of atmospheric metal deposition in many areas, but rarely in China. This study aimed at determining whether atmospheric heavy metal deposition from a Pb-Zn smeltery at Qujiang, Guangdong province, could be accurately reflected both in the inner bark and the outer bark of Masson pine (Pinus massoniana L.). The impact of the emission from smeltery on the soils beneath the trees and the relationships of the concentrations between the soils and the barks were also analyzed. Barks around the bole of Pinus massoniana from a pine forest near a Pb-Zn smeltery at Qujiang and a reference forest at Dinghushan natural reserve were sampled with a stainless knife at an average height of 1.5 m above the ground. Mosses and lichens on the surface barks were cleaned prior to sampling. The samples were carefully divided into the inner bark (living part) and the outer bark (dead part) in the laboratory, and dried and ground, respectively. After being dry-ashed, the powder of the barks was dissolved in HNO3. The solutions were analyzed for iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni) and cobalt (Co) by inductively coupled plasmas emission spectrometry (ICP, PS-1000AT, USA) and Cadmium (Cd) and lead (Pb) by graphite furnace atomic absorption spectrometry (GFAAS, ZEENIT 60, Germany). Surface soils (0-10 cm) beneath the sample trees were also collected and analyzed for the selected metals. Concentrations of the selected metals in soils at Qujiang were far above their environmental background values in the area, except for Fe and Mn, whilst at Dinghushan, they were far below their background values, except for Cd and Co. Levels of the metals, in particular Pb and Zn, in the soils beneath the sample trees at Qujiang were higher than those at Dinghushan with statistical significance. The result suggested that the pine forest soils at Qujiang had a great input of heavy metals from wet and dry atmospheric deposition, with the Pb-Zn smeltery most probably being the source. Levels of Cu, Fe, Mn, Zn, Ni and Pb at Qujiang, both in the inner and the outer bark, were statistically higher than those at Dinghushan. Higher concentrations of Pb, Fe, Zn and Cu may come from the stem-flow of elements leached from the canopy, soil splash on the 1.5 m height and sorption of metals in the mosses and lichens growing on the bark, which were direct or indirect results from the atmospheric deposition. Levels of heavy metals in the outer barks were associated well with the metal concentrations in the soil, reflecting the close relationships between the metal atmospheric deposition and their accumulation in the outer bark of Masson pine. The significant (p<0.01) correlations of Fe-Cu, Fe-Cr, Fe-Pb, Fe-Ni, Pb-Ni, and Pb-Zn in the outer barks at Qujiang again suggested a common source for the metals. The correlation only occurred between Pb and Ni, Cd and Co in the outer barks at Dinghushan, which suggested that those metals must possibly have other uncommon sources. Atmospheric deposition of the selected metals was great at Qujiang, based on the levels in the bark of Pinus massoniana and on the concentrations in the soils beneath the trees compared with that at Dinghushan. Bark of Pinus massoniana, especially the outer bark, was an indicator of metal loading at least at the time of sampling. The results from this study and the techniques employed constituted a new contribution to the development of biogeochemical methods for environmental monitoring particularly in areas with high frequency of pollution in China. The method would be of value for follow up studies aimed at the assessment of industrial pollution in other areas similar with the Pearl River Delta.

Adaptive Modeling, Engineering Analysis and Design of Advanced Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Mukhopadhyay, Vivek; Hsu, Su-Yuen; Mason, Brian H.; Hicks, Mike D.; Jones, William T.; Sleight, David W.; Chun, Julio; Spangler, Jan L.; Kamhawi, Hilmi; Dahl, Jorgen L.

2006-01-01

This paper describes initial progress towards the development and enhancement of a set of software tools for rapid adaptive modeling, and conceptual design of advanced aerospace vehicle concepts. With demanding structural and aerodynamic performance requirements, these high fidelity geometry based modeling tools are essential for rapid and accurate engineering analysis at the early concept development stage. This adaptive modeling tool was used for generating vehicle parametric geometry, outer mold line and detailed internal structural layout of wing, fuselage, skin, spars, ribs, control surfaces, frames, bulkheads, floors, etc., that facilitated rapid finite element analysis, sizing study and weight optimization. The high quality outer mold line enabled rapid aerodynamic analysis in order to provide reliable design data at critical flight conditions. Example application for structural design of a conventional aircraft and a high altitude long endurance vehicle configuration are presented. This work was performed under the Conceptual Design Shop sub-project within the Efficient Aerodynamic Shape and Integration project, under the former Vehicle Systems Program. The project objective was to design and assess unconventional atmospheric vehicle concepts efficiently and confidently. The implementation may also dramatically facilitate physics-based systems analysis for the NASA Fundamental Aeronautics Mission. In addition to providing technology for design and development of unconventional aircraft, the techniques for generation of accurate geometry and internal sub-structure and the automated interface with the high fidelity analysis codes could also be applied towards the design of vehicles for the NASA Exploration and Space Science Mission projects.

Saturn meteorology - A diagnostic assessment of thin-layer configurations for the zonal flow

NASA Technical Reports Server (NTRS)

Allison, M.; Stone, P. H.

1983-01-01

Voyager imaging, infrared, and radio observations for Saturn have been recently interpreted by Smith et al. (1982) as an indication that the jet streams observed at the cloud tops extend to depths greater than the 10,000-bar level. This analysis assumes a maximum latitudinal temperature contrast of a few percent, a mean atmospheric rotation rate at depth given by Saturn's ratio period, and no variation with latitude of the bottom pressure level for the zonal flow system. These assumptions are not, however, firmly constrained by observation. The diagnostic analysis of plausible alternative configurations for Saturn's atmospheric structure demonstrates that a thin weather layer system (confined at mid to high latitudes to levels above 200 bar) cannot be excluded by any of the available observations. A quantitative estimate of the effects of moisture condensation (including the differentiation of mean molecular weight) suggests that these might provide the buoyancy contrasts necessary to support a thin-layer flow provided that Saturn's outer envelope is enriched approximately 10 times in water abundance relative to a solar composition atmosphere and strongly differentiated with latitude at the condensation level.

Delimitation of air space and outer space - Is such a boundary needed now?

NASA Technical Reports Server (NTRS)

Hosenball, S. N.

1983-01-01

A discussion is presented of the question of establishing a boundary between air space and outer space. Four theories and approaches for establishing a delimitation between air space and outer space are examined. Spatial approaches include demarcation based on the division of the atmosphere into layers, demarcation based on aerodynamic characteristics of flight instrumentalities (von Karman Line), demarcation according to the lowest perigee of an orbiting satellite, and demarcation based upon the earth's gravitational effects. The functionalist approach is based on the delimitation or definition of the air space/outer space regime by the purpose and activities for which an object is designed in air space or outer space. The arbitrarist approach is supported by those who wish to draw an arbitrary line between air space and outer space. It is proposed that a pragmatist approach will be more useful than the other three approaches. The pragmatist approach advocates not establishing a boundary between air space and outer space at the present time or in the immediate future. It is argued that there are at present no serious problems that can be resolved by the definition/delimitation of air space and outer space.

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.

Mass and energy flows between the Solar chromosphere, transition region, and corona

NASA Astrophysics Data System (ADS)

Hansteen, V. H.

2017-12-01

A number of increasingly sophisticated numerical simulations spanning the convection zone to corona have shed considerable insight into the role of the magnetic field in the structure and energetics of the Sun's outer atmosphere. This development is strengthened by the wealth of observational data now coming on-line from both ground based and space borne observatories. We discuss what numerical models can tell us about the mass and energy flows in the region of the upper chromosphere and lower corona, using a variety of tools, including the direct comparison with data and the use of passive tracer particles (so-called 'corks') inserted into the simulated flows.

Empirical scaling laws for coronal heating

NASA Technical Reports Server (NTRS)

Golub, L.

1983-01-01

The origins and uses of scaling laws in studies of stellar outer atmospheres are reviewed with particular emphasis on the properties of coronal loops. Some evidence is presented for a fundamental structuring of the solar corona and the thermodynamics of scaling laws are discussed. It is found that magnetic field-related scaling laws can be obtained by relating coronal pressure, temperature, and magnetic field strength. Available data validate this method. Some parameters of the theory, however, must be treated as adjustable, and it is considered necessary to examine data from other stars in order to determine the validity of the parameters. Using detailed observational data, the applicability of single loop models is examined.

Turbine exhaust diffuser with region of reduced flow area and outer boundary gas flow

DOEpatents

Orosa, John

2014-03-11

An exhaust diffuser system and method for a turbine engine. The outer boundary may include a region in which the outer boundary extends radially inwardly toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. At least one gas jet is provided including a jet exit located on the outer boundary. The jet exit may discharge a flow of gas downstream substantially parallel to an inner surface of the outer boundary to direct a portion of the exhaust flow in the diffuser toward the outer boundary to effect a radially outward flow of at least a portion of the exhaust gas flow toward the outer boundary to balance an aerodynamic load between the outer and inner boundaries.

Dual-Band Optical Bench for Terahertz Radiometer for Outer Planet Atmospheres (TROPA)

NASA Technical Reports Server (NTRS)

Schlecht, Erich; Jamnejad, Vahraz

2012-01-01

We have developed a wide-band dual frequency spectrometer for use in deep space planetary atmospheric spectroscopy. The instrument uses a dual-band architecture, both to be able to observe spectral lines from a wide range of atmospheric species, and to allow a higher precision retrieval of temperature/pressure/partial pressure and wind profiles. This dual-band approach requires a new design for the optical bench to couple both frequencies into their respective receivers.

The development and test of a deformable diffraction grating for a stigmatic EUV spectroheliometer

NASA Technical Reports Server (NTRS)

Timothy, J. Gethyn; Walker, A. B. C., Jr.; Morgan, J. S.; Huber, M. C. E.; Tondello, G.

1992-01-01

The objectives were to address currently unanswered fundamental questions concerning the fine scale structure of the chromosphere, transition region, and corona. The unique characteristics of the spectroheliometer was used in combination with plasma diagnostic techniques to study the temperature, density, and velocity structures of specific features in the solar outer atmosphere. A unified understanding was sought of the interplay between the time dependent geometry of the magnetic field structure and the associated flows of mass and energy, the key to which lies in the smallest spatial scales that are unobservable with current EUV instruments. Toroidal diffraction gratings were fabricated and tested by a new technique using an elastically deformable substrate. The toroidal diffraction gratings was procured and tested to be used for the evaluation of the Multi-Anode Microchannel Array (MAMA) detector systems for the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) and UV Coronagraph Spectrometer (UVCS) instruments on the SOHO mission.

A numerical study of active structural acoustic control in a stiffened, double wall cylinder

NASA Technical Reports Server (NTRS)

Grosveld, Ferdinand W.; Coats, T. J.; Lester, H. C.; Silcox, R. J.

1994-01-01

It is demonstrated that active structural acoustic control of complex structural/acoustic coupling can be numerically modeled using finite element and boundary element techniques in conjunction with an optimization procedure to calculate control force amplitudes. Appreciable noise reduction is obtained when the structure is excited at a structural resonance of the outer shell or an acoustic resonance of the inner cavity. Adding ring stiffeners as a connection between the inner and outer shells provides an additional structural transmission path to the interior cavity and coupled the modal behavior of the inner and outer shells. For the case of excitation at the structural resonance of the unstiffened outer shell, adding the stiffeners raises the structural resonance frequencies. The effectiveness of the control forces is reduced due to the off resonance structural response. For excitation at an acoustic cavity resonance, the controller effectiveness is enhanced.

Structural heat pipe. [for spacecraft wall thermal insulation system

NASA Technical Reports Server (NTRS)

Ollendorf, S. (Inventor)

1974-01-01

A combined structural reinforcing element and heat transfer member is disclosed for placement between a structural wall and an outer insulation blanket. The element comprises a heat pipe, one side of which supports the outer insulation blanket, the opposite side of which is connected to the structural wall. Heat penetrating through the outer insulation blanket directly reaches the heat pipe and is drawn off, thereby reducing thermal gradients in the structural wall. The element, due to its attachment to the structural wall, further functions as a reinforcing member.

Sprayed skin turbine component

DOEpatents

Allen, David B

2013-06-04

Fabricating a turbine component (50) by casting a core structure (30), forming an array of pits (24) in an outer surface (32) of the core structure, depositing a transient liquid phase (TLP) material (40) on the outer surface of the core structure, the TLP containing a melting-point depressant, depositing a skin (42) on the outer surface of the core structure over the TLP material, and heating the assembly, thus forming both a diffusion bond and a mechanical interlock between the skin and the core structure. The heating diffuses the melting-point depressant away from the interface. Subsurface cooling channels (35) may be formed by forming grooves (34) in the outer surface of the core structure, filling the grooves with a fugitive filler (36), depositing and bonding the skin (42), then removing the fugitive material.

Preface to the special issue of PSS on "Surfaces, atmospheres and magnetospheres of the outer planets, their satellites and ring systems: Part XII″

NASA Astrophysics Data System (ADS)

Coustenis, A.; Atreya, S.; Castillo-Rogez, J.; Mueller-Wodarg, I.; Spilker, L.; Strazzulla, G.

2018-06-01

This issue contains six articles on original research and review papers presented in the past year in sessions organized during several international meetings and congresses including the European Geosciences Union (EGU), European Planetary Science Congress (EPSC) and others. The manuscripts cover recent observations and models of the atmospheres, magnetospheres and surfaces of the giant planets and their satellites based on ongoing and recent planetary missions. Concepts of architecture and payload for future space missions are also presented. The six articles in this special issue cover a variety of objects in the outer solar system ranging from Jupiter to Neptune and the possibilities for their exploration. A brief introductory summary of their findings follows.

Plasma Flow Past Cometary and Planetary Satellite Atmospheres

NASA Technical Reports Server (NTRS)

Combi, Michael R.; Gombosi, Tamas I.; Kabin, Konstantin

2000-01-01

The tenuous atmospheres and ionospheres of comets and outer planet satellites share many common properties and features. Such similarities include a strong interaction with their outer radiation, fields and particles environs. For comets the interaction is with the magnetized solar wind plasma, whereas for satellites the interaction is with the strongly magnetized and corotating planetary magnetospheric plasma. For this reason there are many common or analogous physical regimes, and many of the same modeling techniques are used to interpret remote sensing and in situ measurements in order to study the important underlying physical phenomena responsible for their appearances. We present here a review of various modeling approaches which are used to elucidate the basic properties and processes shaping the energetics and dynamics of these systems which are similar in many respects.

Structurally compliant microbearing devices and methods thereof

NASA Technical Reports Server (NTRS)

Boedo, Stephen (Inventor); Grande, William (Inventor)

2011-01-01

A microbearing device includes at least one inner bearing structure, at least one outer bearing structure, and one or more fasteners. Each of the one or more fasteners is connected between the inner bearing structure and the outer bearing structure and the inner bearing structure is substantially elastic.

Elemental concentrations in foliage of red maple, red oak, and white oak in relation to atmospheric deposition in Pennsylvania

Treesearch

D. D. Davis; J. M. Skelly; B. L. Nash

1995-01-01

Foliage was sampled in June and late August-early September in 1988 and 1989 from the outer crowns of codominant red maple (Acer rubrum L.), northern red oak (Quercus rubra L.), and white oak (Q. alba L.) trees in forest stands along an atmospheric deposition gradient in north-central Pennsylvania. Leaf samples...

Two-axis tracker for solar panels and the like

DOEpatents

Liao, Henry H.

2013-04-16

A tracker including an outer post having elongated bore and a lower end mounted on a sub-structure, an inner pole rotatably received in the elongated bore, a lower bearing in the bore adjacent a lower end of the outer post and attached thereto to be constrained from lateral movement and mounted on the sub-structure such that a lower end of the inner pole rests on and is supported by the lower bearing, an upper bearing near an upper end of the outer post, a circumferential drive supported on the outer post for rotating the inner pole relative to the outer post, such that substantially a full weight of a load on the inner pole is directly transmitted to the sub-structure and lateral force and torque leverage are placed on a full length of the outer post by way of the upper and lower bearing.

Turbine airfoil with dual wall formed from inner and outer layers separated by a compliant structure

DOEpatents

Campbell,; Christian X. , Morrison; Jay, A [Oviedo, FL

2011-12-20

A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a compliant structure. The compliant structure may be configured such that the outer layer may thermally expand without limitation by the inner layer. The compliant structure may be formed from a plurality of pedestals positioned generally parallel with each other. The pedestals may include a first foot attached to a first end of the pedestal and extending in a first direction aligned with the outer layer, and may include a second foot attached to a second end of the pedestal and extending in a second direction aligned with the inner layer.

NUMERICAL SIMULATIONS OF CORONAL HEATING THROUGH FOOTPOINT BRAIDING

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

Hansteen, V.; Pontieu, B. De; Carlsson, M.

2015-10-01

Advanced three-dimensional (3D) radiative MHD simulations now reproduce many properties of the outer solar atmosphere. When including a domain from the convection zone into the corona, a hot chromosphere and corona are self-consistently maintained. Here we study two realistic models, with different simulated areas, magnetic field strength and topology, and numerical resolution. These are compared in order to characterize the heating in the 3D-MHD simulations which self-consistently maintains the structure of the atmosphere. We analyze the heating at both large and small scales and find that heating is episodic and highly structured in space, but occurs along loop-shaped structures, andmore » moves along with the magnetic field. On large scales we find that the heating per particle is maximal near the transition region and that widely distributed opposite-polarity field in the photosphere leads to a greater heating scale height in the corona. On smaller scales, heating is concentrated in current sheets, the thicknesses of which are set by the numerical resolution. Some current sheets fragment in time, this process occurring more readily in the higher-resolution model leading to spatially highly intermittent heating. The large-scale heating structures are found to fade in less than about five minutes, while the smaller, local, heating shows timescales of the order of two minutes in one model and one minutes in the other, higher-resolution, model.« less

The presence of OMP inclusion bodies in a Escherichia coli K-12 mutated strain is not related to lipopolysaccharide structure.

PubMed

Corsaro, M Michela; Parrilli, Ermenegilda; Lanzetta, Rosa; Naldi, Teresa; Pieretti, Giuseppina; Lindner, Buko; Carpentieri, Andrea; Parrilli, Michelangelo; Tutino, M Luisa

2009-08-01

The role of lipopolysaccharides (LPSs) in the biogenesis of outer membrane proteins have been investigated in several studies. Some of these analyses showed that LPS is required for correct and efficient folding of outer membrane proteins; other studies support the idea of independence of outer membrane proteins biogenesis from LPS structure. In this article, we investigated the involvement of LPS structure in the anomalous aggregation of outer membrane proteins in a E. coli mutant strain (S17-1(lambdapir)). To achieve this aim, the LPS structure of the mutant strain was carefully determined and compared with the E. coli K-12 one. It turned out that LPS of these two strains differs in the inner core for the absence of a heptose residue (HepIII). We demonstrated that this difference is due to a mutation in waaQ, a gene encoding the transferase for the branch heptose HepIII residue. The mutation was complemented to find out if the restoration of LPS structure influenced the observed outer membrane proteins aggregation. Data reported in this work demonstrated that, in E. coli S17-1(lambdapir) there is no influence of LPS structure on the outer membrane proteins inclusion bodies formation.

Steamworlds: Atmospheric Structure and Critical Mass of Planets Accreting Icy Pebbles

NASA Astrophysics Data System (ADS)

Chambers, John

2017-11-01

In the core accretion model, gas-giant planets first form a solid core, which then accretes gas from a protoplanetary disk when the core exceeds a critical mass. Here, we model the atmosphere of a core that grows by accreting ice-rich pebbles. The ice fraction of pebbles evaporates in warm regions of the atmosphere, saturating it with water vapor. Excess water precipitates to lower altitudes. Beneath an outer radiative region, the atmosphere is convective, following a moist adiabat in saturated regions due to water condensation and precipitation. Atmospheric mass, density, and temperature increase with core mass. For nominal model parameters, planets with core masses (ice + rock) between 0.08 and 0.16 Earth masses have surface temperatures between 273 and 647 K and form an ocean. In more massive planets, water exists as a supercritical convecting fluid mixed with gas from the disk. Typically, the core mass reaches a maximum (the critical mass) as a function of the total mass when the core is 2-5 Earth masses. The critical mass depends in a complicated way on pebble size, mass flux, and dust opacity due to the occasional appearance of multiple core-mass maxima. The core mass for an atmosphere of 50% hydrogen and helium may be a more robust indicator of the onset of gas accretion. This mass is typically 1-3 Earth masses for pebbles that are 50% ice by mass, increasing with opacity and pebble flux and decreasing with pebble ice/rock ratio.

Planetary Entry Probes and Mass Spectroscopy: Tools and Science Results from In Situ Studies of Planetary Atmospheres and Surfaces

NASA Technical Reports Server (NTRS)

Niemann, Hasso B.

2007-01-01

Probing the atmospheres and surfaces of the planets and their moons with fast moving entry probes has been a very useful and essential technique to obtain in situ or quasi in situ scientific data (ground truth) which could not otherwise be obtained from fly by or orbiter only missions and where balloon, aircraft or lander missions are too complex and costly. Planetary entry probe missions have been conducted successfully on Venus, Mars, Jupiter and Titan after having been first demonstrated in the Earth's atmosphere. Future missions will hopefully also include more entry probe missions back to Venus and to the outer planets. 1 he success of and science returns from past missions, the need for more and better data, and a continuously advancing technology generate confidence that future missions will be even more successful with respect to science return and technical performance. I'he pioneering and tireless work of Al Seiff and his collaborators at the NASA Ames Research Center had provided convincing evidence of the value of entry probe science and how to practically implement flight missions. Even in the most recent missions involving entry probes i.e. Galileo and Cassini/Huygens A1 contributed uniquely to the science results on atmospheric structure, turbulence and temperature on Jupiter and Titan.

Seamless metal-clad fiber-reinforced organic matrix composite structures and process for their manufacture

NASA Technical Reports Server (NTRS)

Bluck, Raymond M. (Inventor); Bush, Harold G. (Inventor); Johnson, Robert R. (Inventor)

1990-01-01

A metallic outer sleeve is provided which is capable of enveloping a hollow metallic inner member having continuous reinforcing fibers attached to the distal end thereof. The inner member is then introduced into outer sleeve until inner member is completely enveloped by outer sleeve. A liquid matrix member is then injected into space between inner member and outer sleeve. A pressurized heat transfer medium is flowed through the inside of inner member, thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. The novelty of this invention resides in the development of a efficient method of producing seamless metal clad fiber reinforced organic matrix composite structures.

15 CFR 923.32 - Lakeward or seaward boundary.

Code of Federal Regulations, 2013 CFR

2013-01-01

... or Pacific Ocean, or the Gulf of Mexico, the seaward boundary is the outer limit of state title and...) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL RESOURCE...

In situ 3-D mapping of pore structures and hollow grains of interplanetary dust particles with phase contrast X-ray nanotomography

NASA Astrophysics Data System (ADS)

Hu, Z. W.; Winarski, R. P.

2016-09-01

Unlocking the 3-D structure and properties of intact chondritic porous interplanetary dust particles (IDPs) in nanoscale detail is challenging, which is also complicated by atmospheric entry heating, but is important for advancing our understanding of the formation and origins of IDPs and planetary bodies as well as dust and ice agglomeration in the outer protoplanetary disk. Here, we show that indigenous pores, pristine grains, and thermal alteration products throughout intact particles can be noninvasively visualized and distinguished morphologically and microstructurally in 3-D detail down to ~10 nm by exploiting phase contrast X-ray nanotomography. We have uncovered the surprisingly intricate, submicron, and nanoscale pore structures of a ~10-μm-long porous IDP, consisting of two types of voids that are interconnected in 3-D space. One is morphologically primitive and mostly submicron-sized intergranular voids that are ubiquitous; the other is morphologically advanced and well-defined intragranular nanoholes that run through the approximate centers of ~0.3 μm or lower submicron hollow grains. The distinct hollow grains exhibit complex 3-D morphologies but in 2-D projections resemble typical organic hollow globules observed by transmission electron microscopy. The particle, with its outer region characterized by rough vesicular structures due to thermal alteration, has turned out to be an inherently fragile and intricately submicron- and nanoporous aggregate of the sub-μm grains or grain clumps that are delicately bound together frequently with little grain-to-grain contact in 3-D space.

Heliophysics: The Solar and Space Physics of a New Era. Recommended Roadmap for Science and Technology 2009-2030

NASA Technical Reports Server (NTRS)

Christensen, Andrew B.; Spann, James; Cyr, O. C.; Cummings, Alan; Heelis, Roderick; Hill, Frank; Immel, Thomas; Kasper, Justin; Kistler, Lynn; Kuhn, Jeffrey;

Mass spectrometric measurements of atmospheric composition

NASA Technical Reports Server (NTRS)

Hoffman, J. H.

1974-01-01

The development of a magnetic sector field analyzer for continuous sampling and measurement of outer planetary atmospheres is discussed. Special features of the analyzer include a dynamic range of 10 to the minus 7th power, a mass range from 1 to 48 AMU, two ion sensitivities, a special scan time of 35 sec at 14 BPS, and the use of ion counting techniques for analysis.

The Role of Spectroscopy in Research on the Neutral Atmospheres of the Outer Solar System

NASA Astrophysics Data System (ADS)

Orton, Glenn S.

2013-06-01

Remote-sensing observations of Jupiter, Saturn, Uranus and Neptune, as well as Titan - Saturn's largest satellite, and the spectroscopic information required to interpret these observations play a pivotal role in the exploration of the atmospheres of the outer solar system. We rely on well-mixed constituents to derive temperatures unambiguously, with only the collision-induced absorption and quadrupole transitions of H_2 and CH_4 in Jupiter and Saturn fulfilling that role. Condensate and chemically disequilibrated molecules (e.g. NH_3 and PH_3) act as indirect tracers that inform us of the strength of vertical winds. Higher-order hydrocarbons are present in all these atmospheres and their abundances and distribution acts as a tracer for stratospheric circulation and chemistry. The platforms on which planetary spectroscopy is done include a variety of ground-based facilities that observe the planets from the visible through radio regions. Airborne facilities, such as NASA's SOFIA, together with Earth-proximal facilities in space, allow both increased sensitivity and wider spectral access. Spectrometers on interplanetary missions have allowed us to examine the spatial and temporal variability of atmospheric properties that are not possible from the Earth. Several needs and challenges remain, and a constant dialog between those in the planetary exploration community and laboratory spectroscopists and theorists has been and will continue to be an important component of progress in atmospheric research. -

Influence of the outer boundary condition on models of AGB stars

NASA Astrophysics Data System (ADS)

Wagstaff, G.; Weiss, A.

2018-07-01

Current implementations of the stellar atmosphere typically derive boundary conditions for the interior model from either grey plane-parallel atmospheres or scaled solar atmospheres, neither of which can be considered to have appropriate underlying assumptions for the Thermally Pulsing Asymptotic Giant Branch (TP-AGB). This paper discusses the treatment and influence of the outer boundary condition within stellar evolution codes, and the resulting effects on the AGB evolution. The complex interaction of processes, such as the third dredge up and mass-loss, governing the TP-AGB can be affected by varying the treatment of this boundary condition. Presented here are the results from altering the geometry, opacities, and the implementation of a grid of MARCS/COMARCS model atmospheres in order to improve this treatment. Although there are changes in the TP-AGB evolution, observable quantities, such as the final core mass, are not significantly altered as a result of the change of atmospheric treatment. During the course of the investigation, a previously unseen phenomenon in the AGB models was observed and further investigated. This is believed to be physical, although arising from specific conditions which make its presence unlikely. If it were present in stars, this phenomenon would increase the carbon-star lifetime above 10 Myr and increase the final core mass by ˜0.1 M⊙ in the narrow initial-mass range where it was observed (˜2-2.3 M⊙).

Influence of the Outer Boundary Condition on models of AGB stars

NASA Astrophysics Data System (ADS)

Wagstaff, G.; Weiss, A.

2018-04-01

Current implementations of the stellar atmosphere typically derive boundary conditions for the interior model from either grey plane-parallel atmospheres or scaled solar atmospheres, neither of which can be considered to have appropriate underlying assumptions for the Thermally Pulsing Asymptotic Giant Branch (TP-AGB). This paper discusses the treatment and influence of the outer boundary condition within stellar evolution codes, and the resulting effects on the AGB evolution. The complex interaction of processes, such as the third dredge up and mass loss, governing the TP-AGB can be affected by varying the treatment of this boundary condition. Presented here are the results from altering the geometry, opacities and the implementation of a grid of MARCS/COMARCS model atmospheres in order to improve this treatment. Although there are changes in the TP-AGB evolution, observable quantities, such as the final core mass, are not significantly altered as a result of the change of atmospheric treatment. During the course of the investigation, a previously unseen phenomena in the AGB models was observed and further investigated. This is believed to be physical, although arising from specific conditions which make its presence unlikely. If it were present in stars, this phenomenon would increase the carbon-star lifetime above 10Myr and increase the final core mass by ˜0.1M⊙ in the narrow initial-mass range where it was observed (˜2 - 2.3M⊙).

Direct Communication to Earth from Probes

NASA Technical Reports Server (NTRS)

Bolton, Scott J.; Folkner, William M.; Abraham, Douglas S.

2005-01-01

A viewgraph presentation on outer planetary probe communications to Earth is shown. The topics include: 1) Science Rational for Atmospheric Probes to the Outer Planets; 2) Controlling the Scientific Appetite; 3) Learning more about Jupiter before we send more probes; 4) Sample Microwave Scan From Juno; 5) Jupiter s Deep Interior; 6) The Square Kilometer Array (SKA): A Breakthrough for Radio Astronomy; 7) Deep Space Array-based Network (DSAN); 8) Probe Direct-to-Earth Data Rate Calculations; 9) Summary; and 10) Enabling Ideas.

Dynamics of the Outer Planets

DTIC Science & Technology

1992-01-01

30 PM A Dark Side Atmosphere on Io? Ray LeBeau viii rJar 𔃻 L7 ~ E > E 2t m E L 91, -l- IN0. Table of Contents Lectures 1 - An Overview of the Outer...fields, with evidence of cotmiderable complexity at higher haruwucn. The interactwo of charged partieles with the~ e magnetic fields prtoduces p-rmodic...latitutd Two p,•ihble e -xplanatti’ I for thins •re ither that the atmxospherir cirrultmon s w) efficewnt as to r-dmjribute al the rnrriry in the

Monodeurated methane in the outer solar system. 2. Its detection on Uranus at 1.6 microns

NASA Technical Reports Server (NTRS)

Debergh, C.; Lutz, B. L.; Owen, T.; Brault, J.; Chauville, J.

1985-01-01

Deuterium in the atmosphere of Uranus has been studied only via measurements of the exceedingly weak dipole lines of hydrogen-deuteride (HD) seen in the visible region of the spectrum. The other sensitive indicator of deuterium in the outer solar system is monodeuterated methane (CH3D) but the two bands normally used ot study this molecule, NU sub 2 near 2200 1/cm and NU sub 6 near 1161 1/cm, have not been detected in Uranus.

Phobos/Deimos sample return via solar sail.

PubMed

Matloff, Gregory L; Taylor, Travis; Powell, Conley; Moton, Tryshanda

2005-12-01

A sample-return mission to the Martian satellites using a con-temporary solar sail for all post-Earth-escape propulsion is proposed. The 0.015 kg/m(2) areal mass-thickness sail unfurls after launch and injection onto a Mars-bound Hohmann-transfer ellipse. Structure and payload increase spacecraft areal mass thickness to 0.028 kg/m(2). During the Mars encounter, the sail functions as a parachute in the outer atmosphere of Mars to accomplish aerocapture. On-board thrusters or the sail maneuver the spacecraft into an orbit with periapsis near Mars and apoapsis near Phobos. The orbit is circularized for Phobos-rendezvous; surface samples are collected. The sail then raises the orbit for Deimos-rendezvous and sample collection. The sail next places the spacecraft on an Earth-bound Hohmann-transfer ellipse. During Earth encounter, the sail accomplishes Earth-aerocapture or partially decelerates the sample container for entry into the Earth's atmosphere. Mission mass budget is about 218 grams and mission duration is less than five years.

Novel Hybrid Ablative/Ceramic Heatshield for Earth Atmospheric Re-Entry

NASA Astrophysics Data System (ADS)

Barcena, J.; Florez, S.; Perez, B.; Pinaud, G.; Bouilly, J.-M.; Fischer, W. P. P.; de Montburn, A.; Descomps, M.; Zuber, C.; Rotaermel, W.; Hald, H.; Pereira, C.; Mergia, K.; Triantou, K.; Marinou, A.; Vekinis, G.; Ionescu, G.; Ban, C.; Stefan, A.; Leroy, V.; Bernard, D.; Massuti, B.; Herdrich, G.

2014-06-01

Original approaches based on ablative materials and novel TPS solutions are required for space applications, where resistance to extreme oxidative environments and high temperatures are required. For future space exploration the demands for the thermal shield go beyond the current state-of-the-art. Therefore, the development of new thermal protection materials and systems at a reasonable mass budget is absolutely essential to ensure European non-dependence on corresponding restricted technologies. The three year long FP7 project HYDRA aims at the development of a novel thermal protection system through the integration of a low density ablative outer-shield on top of an advanced thermo-structural ceramic composite layer and will provide an innovative technology solution consistent with the capabilities of European technologies and material providers. This paper summarizes the current status of the scientific activities carried out after two years of progress in terms of design, integration and verification of a robust and lightweight thermal shield solution for atmospheric earth re-entry.

Phobos/Deimos Sample Return via Solar Sail

NASA Technical Reports Server (NTRS)

Matloff, Gregory L.; Taylor, Travis; Powell, Conley; Moton, Tryshanda

2004-01-01

Abstract A sample-return mission to the martian satellites using a contemporary solar sail for all post-Earth-escape propulsion is proposed. The 0.015 kg/sq m areal mass-thickness sail unfurls after launch and injection onto a Mars-bound Hohmann-transfer ellipse. Structure and pay!oad increase spacecraft areal mass thickness to 0.028 kg/sq m. During Mars-encounter, the sail functions parachute-like in Mars s outer atmosphere to accomplish aerocapture. On-board thrusters or the sail maneuver the spacecraft into an orbit with periapsis near Mars and apoapsis near Phobos. The orbit is circularized for Phobos-rendezvous; surface samples are collected. The sail then raises the orbit for Deimos-rendezvous and sample collection. The sail next places the spacecraft on an Earth-bound Hohmann-transfer ellipse. During Earth-encounter, the sail accomplishes Earth-aerocapture or partially decelerates the sample container for entry into Earth s atmosphere. Mission mass budget is about 218 grams and; mission duration is <5 years.

Process for the manufacture of seamless metal-clad fiber-reinforced organic matrix composite structures

NASA Technical Reports Server (NTRS)

Bluck, Raymond M. (Inventor); Bush, Harold G. (Inventor); Johnson, Robert R. (Inventor)

1991-01-01

A process for producing seamless metal-clad composite structures includes providing a hollow, metallic inner member and an outer sleeve to surround the inner member and define an inner space therebetween. A plurality of continuous reinforcing fibers is attached to the distal end of the outside diameter of the inner member, and the inner member is then introduced, distal end first, into one end of the outer sleeve. The inner member is then moved, distal end first, into the outer sleeve until the inner member is completely enveloped by the outer sleeve. A liquid matrix material is then injected into the space containing the reinforcing fibers between the inner member and the outer sleeve. Next a pressurized heat transfer medium is passed through the inner member to cure the liquid matrix material. Finally, the wall thickness of both the inner member and the outer sleeve are reduced to desired dimensions by chemical etching, which adjusts the thermal expansion coefficient of the metal-clad composite structure to a desired value.

Effects of Complex Interplanetary Structures on the Dynamics of the Earth's Outer Radiation Belt During the 16-30 September 2014 Period: II) Corotating Solar Wind Stream

NASA Astrophysics Data System (ADS)

Souza, V. M. C. E. S.; Da Silva, L. A.; Sibeck, D. G.; Alves, L. R.; Jauer, P. R.; Dias Silveira, M. V.; Medeiros, C.; Marchezi, J.; Rockenbach, M.; Baker, D. N.; Kletzing, C.; Kanekal, S. G.; Georgiou, M.; Mendes, O., Jr.; Dal Lago, A.; Vieira, L. E. A.

2015-12-01

We present a case study describing the dynamics of the outer radiation belt for two different solar wind conditions. First, we discuss a dropout of outer belt energetic electron fluxes corresponding to the arrival of an interplanetary coronal mass ejection (ICME) followed by a corotating stream in September 2014. Second, we discuss the reformation of the outer radiation belt that began on September 22nd. We find that the arrival of the ICME and the corotating interaction region that preceded the stream cause a long-duration (many day) dropout of high-energy electrons. The recovery in radiation belt fluxes only begins when the high-speed stream begins to develop IMF Bz fluctuations and auroral activity resumes. Furthermore, during periods in which several consecutive solar wind structures appear, the first structure primes the outer radiation belt prior to the interaction of the subsequent solar wind structures with the magnetosphere. Consequently, the evolution of the outer radiation belt through the solar cycle is significantly affected by the dominant structure of each phase of the cycle. We use energetic electron and magnetic field observations provided by the Van Allen Probes, THEMIS, and GOES missions.

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.

Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors

PubMed Central

McWilliams, R. Stewart; Dalton, D. Allen; Konôpková, Zuzana; Mahmood, Mohammad F.; Goncharov, Alexander F.

2015-01-01

The noble gases are elements of broad importance across science and technology and are primary constituents of planetary and stellar atmospheres, where they segregate into droplets or layers that affect the thermal, chemical, and structural evolution of their host body. We have measured the optical properties of noble gases at relevant high pressures and temperatures in the laser-heated diamond anvil cell, observing insulator-to-conductor transformations in dense helium, neon, argon, and xenon at 4,000–15,000 K and pressures of 15–52 GPa. The thermal activation and frequency dependence of conduction reveal an optical character dominated by electrons of low mobility, as in an amorphous semiconductor or poor metal, rather than free electrons as is often assumed for such wide band gap insulators at high temperatures. White dwarf stars having helium outer atmospheres cool slower and may have different color than if atmospheric opacity were controlled by free electrons. Helium rain in Jupiter and Saturn becomes conducting at conditions well correlated with its increased solubility in metallic hydrogen, whereas a deep layer of insulating neon may inhibit core erosion in Saturn. PMID:26080401

Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors

DOE PAGES

McWilliams, R. Stewart; Dalton, D. Allen; Konopkova, Zuzana; ...

2015-06-16

The noble gases are elements of broad importance across science and technology, and are primary constituents of planetary and stellar atmospheres, where they segregate into droplets or layers that affect the thermal, chemical, and structural evolution of their host body. We have measured the optical properties of noble gases at relevant high pressures and temperatures in the laser-heated diamond anvil cell, observing insulator-to-conductor transformations in dense helium, neon, argon, and xenon at 4,000 to 15,000 K and pressures of 15-52 GPa. The thermal activation and frequency-dependence of conduction reveal an optical character dominated by electrons of low mobility, as inmore » an amorphous semiconductor or poor metal, rather than free electrons as is often assumed for such wide band gap insulators at high temperatures. White dwarf stars having helium outer atmospheres cool slower and may have different color than if atmospheric opacity were controlled by free-electrons. As a result, helium rain in Jupiter and Saturn becomes conducting at conditions well correlated with increased solubility in metallic hydrogen, while a deep layer of insulating neon may inhibit core erosion in Saturn.« less

Spherically symmetric, expanding, non-LTE model atmospheres for novae during their early stages

NASA Technical Reports Server (NTRS)

Hauschildt, P. H.; Wehrse, R.; Starrfield, S.; Shaviv, G.

1992-01-01

In the continuum and line-blanketed models presented here, nova atmospheres are characterized by a very slow decrease of density with increasing radius. This feature leads to very large geometrical extensions so that there are large temperature differences between the inner and outer parts of the line-forming regions. The theoretical spectra show a large IR excess and a small Balmer jump which may be either in absorption or in emission. For the parameters considered (effective temperature of about 10 exp 4 K, L = 2 x 10 exp 4 solar luminosities, outer boundary density of about 3 x 10 exp -15 g cm exp -3, mass-loss rate of 10 exp -5 solar masses/yr), most lines are in absorption. The effects of changes in the abundances of the heavy elements on the emergent spectra are discussed. The strong unidentified features observed in ultraviolet spectra of novae are found in actuality to be regions of transparency within the Fe 'forest'. Ultraviolet spectra obtained from the IUE archives are displayed, and spectral synthesis of these spectra is done using the theoretical atmospheres.

STRUCTURAL ASSESSMENT OF HYPERAUTOFLUORESCENT RING IN PATIENTS WITH RETINITIS PIGMENTOSA

PubMed Central

LIMA, LUIZ H.; CELLA, WENER; GREENSTEIN, VIVIENNE C.; WANG, NAN-KAI; BUSUIOC, MIHAI; THEODORE SMITH, R.; YANNUZZI, LAWRENCE A.; TSANG, STEPHEN H.

2009-01-01

Purpose To analyze the retinal structure underlying the hyperautofluorescent ring visible on fundus autofluorescence in patients with retinitis pigmentosa. Methods Twenty-four eyes of 13 patients with retinitis pigmentosa, aged 13 years to 67 years, were studied. The integrity of the photoreceptor cilia, also known as the inner/outer segment junction of the photoreceptors, the outer nuclear layer, and retinal pigment epithelium, was evaluated outside, across, and inside the ring with spectral-domain optical coherence tomography (OCT). Results Inside the foveal area, fundus autofluorescence did not detect abnormalities. Outside the ring, fundus autofluorescence revealed hypoautofluorescence compatible with the photoreceptor/retinal pigment epithelium degeneration. Spectral-domain OCT inside the ring, in the area of normal foveal fundus autofluorescence, revealed an intact retinal structure in all eyes and total retinal thickness values that were within normal limits. Across the ring, inner/outer segment junction disruption was observed and the outer nuclear layer was decreased in thickness in a centrifugal direction in all eyes. Outside the hyperautofluorescent ring, the inner/outer segment junction and the outer nuclear layer appeared to be absent and there were signs of retinal pigment epithelium degeneration. Conclusion Disruption of the inner/outer segment junction and a decrease in outer retinal thickness were found across the central hyperautofluorescent ring seen in retinitis pigmentosa. Outer segment phagocytosis by retinal pigment epithelium is necessary for the formation of an hyperautofluorescent ring. PMID:19584660

Simulation study of communication link for Pioneer Saturn/Uranus atmospheric entry probe. [signal acquisition by candidate modem for radio link

NASA Technical Reports Server (NTRS)

Hinrichs, C. A.

1974-01-01

A digital simulation is presented for a candidate modem in a modeled atmospheric scintillation environment with Doppler, Doppler rate, and signal attenuation typical of the radio link conditions for an outer planets atmospheric entry probe. The results indicate that the signal acquisition characteristics and the channel error rate are acceptable for the system requirements of the radio link. The simulation also outputs data for calculating other error statistics and a quantized symbol stream from which error correction decoding can be analyzed.

BBSome function is required for both the morphogenesis and maintenance of the photoreceptor outer segment

PubMed Central

Hsu, Ying; Kim, Gunhee; Zhang, Qihong; Datta, Poppy; Seo, Seongjin

2017-01-01

Genetic mutations disrupting the structure and function of primary cilia cause various inherited retinal diseases in humans. Bardet-Biedl syndrome (BBS) is a genetically heterogeneous, pleiotropic ciliopathy characterized by retinal degeneration, obesity, postaxial polydactyly, intellectual disability, and genital and renal abnormalities. To gain insight into the mechanisms of retinal degeneration in BBS, we developed a congenital knockout mouse of Bbs8, as well as conditional mouse models in which function of the BBSome (a protein complex that mediates ciliary trafficking) can be temporally inactivated or restored. We demonstrate that BBS mutant mice have defects in retinal outer segment morphogenesis. We further demonstrate that removal of Bbs8 in adult mice affects photoreceptor function and disrupts the structural integrity of the outer segment. Notably, using a mouse model in which a gene trap inhibiting Bbs8 gene expression can be removed by an inducible FLP recombinase, we show that when BBS8 is restored in immature retinas with malformed outer segments, outer segment extension can resume normally and malformed outer segment discs are displaced distally by normal outer segment structures. Over time, the retinas of the rescued mice become morphologically and functionally normal, indicating that there is a window of plasticity when initial retinal outer segment morphogenesis defects can be ameliorated. PMID:29049287

Method for adhering a coating to a substrate structure

DOEpatents

Taxacher, Glenn Curtis; Crespo, Andres Garcia; Roberts, III, Herbert Chidsey

2015-02-17

A method for adhering a coating to a substrate structure comprises selecting a substrate structure having an outer surface oriented substantially parallel to a direction of radial stress, modifying the outer surface to provide a textured region having steps to adhere a coating thereto, and applying a coating to extend over at least a portion of the textured region, wherein the steps are oriented substantially perpendicular to the direction of radial stress to resist deformation of the coating relative to the substrate structure. A rotating component comprises a substrate structure having an outer surface oriented substantially parallel to a direction of radial stress. The outer surface defines a textured region having steps to adhere a coating thereto, and a coating extends over at least a portion of the textured region. The steps are oriented substantially perpendicular to the direction of radial stress to resist creep.

Turbine exhaust diffuser with a gas jet producing a coanda effect flow control

DOEpatents

Orosa, John; Montgomery, Matthew

2014-02-11

An exhaust diffuser system and method for a turbine engine includes an inner boundary and an outer boundary with a flow path defined therebetween. The inner boundary is defined at least in part by a hub structure that has an upstream end and a downstream end. The outer boundary may include a region in which the outer boundary extends radially inward toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. The hub structure includes at least one jet exit located on the hub structure adjacent to the upstream end of the tail cone. The jet exit discharges a flow of gas substantially tangential to an outer surface of the tail cone to produce a Coanda effect and direct a portion of the exhaust flow in the diffuser toward the inner boundary.

Computations and estimates of rate coefficients for hydrocarbon reactions of interest to the atmospheres of outer solar system

NASA Technical Reports Server (NTRS)

Laufer, A. H.; Gardner, E. P.; Kwok, T. L.; Yung, Y. L.

1983-01-01

The rate coefficients, including Arrhenius parameters, have been computed for a number of chemical reactions involving hydrocarbon species for which experimental data are not available and which are important in planetary atmospheric models. The techniques used to calculate the kinetic parameters include the Troe and semiempirical bond energy-bond order (BEBO) or bond strength-bond length (BSBL) methods.

Characterization of airborne ice-nucleation-active bacteria and bacterial fragments

NASA Astrophysics Data System (ADS)

Šantl-Temkiv, Tina; Sahyoun, Maher; Finster, Kai; Hartmann, Susan; Augustin-Bauditz, Stefanie; Stratmann, Frank; Wex, Heike; Clauss, Tina; Nielsen, Niels Woetmann; Sørensen, Jens Havskov; Korsholm, Ulrik Smith; Wick, Lukas Y.; Karlson, Ulrich Gosewinkel

2015-05-01

Some bacteria have the unique capacity of synthesising ice-nucleation-active (INA) proteins and exposing them at their outer membrane surface. As INA bacteria enter the atmosphere, they may impact the formation of clouds and precipitation. We studied members of airborne bacterial communities for their capacity to catalyse ice formation and we report on the excretion of INA proteins by airborne Pseudomonas sp. We also observed for the first time that INA biological fragments <220 nm were present in precipitation samples (199 and 482 INA fragments per L of precipitation), which confirms the presence of submicron INA biological fragments in the atmosphere. During 14 precipitation events, strains affiliated with the genus Pseudomonas, which are known to carry ina genes, were dominant. A screening for INA properties revealed that ∼12% of the cultivable bacteria caused ice formation at ≤-7 °C. They had likely been emitted to the atmosphere from terrestrial surfaces, e.g. by convective transport. We tested the ability of isolated INA strains to produce outer membrane vesicles and found that two isolates could do so. However, only very few INA vesicles were released per INA cell. Thus, the source of the submicron INA proteinaceous particles that we detected in the atmosphere remains to be elucidated.

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.

OBSERVING CASCADES OF SOLAR BULLETS AT HIGH RESOLUTION. II

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

Scullion, E.; Engvold, O.; Lin, Y.

High resolution observations from the Swedish 1-m Solar Telescope revealed bright, discrete, blob-like structures (which we refer to as solar bullets) in the Hα 656.28 nm line core that appear to propagate laterally across the solar atmosphere as clusters in active regions (ARs). These small-scale structures appear to be field aligned and many bullets become triggered simultaneously and traverse collectively as a cluster. Here, we conduct a follow-up study on these rapidly evolving structures with coincident observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly. With the co-aligned data sets, we reveal (a) an evolving multithermal structure in the bullet clustermore » ranging from chromospheric to at least transition region temperatures, (b) evidence for cascade-like behavior and corresponding bidirectional motions in bullets within the cluster, which indicate that there is a common source of the initial instability leading to bullet formation, and (c) a direct relationship between co-incident bullet velocities observed in Hα and He ii 30.4 nm and an inverse relationship with respect to bullet intensity in these channels. We find evidence supporting that bullets are typically composed of a cooler, higher density core detectable in Hα with a less dense, hotter, and fainter co-moving outer sheath. Bullets unequivocally demonstrate the finely structured nature of the AR corona. We have no clear evidence for bullets being associated with locally heated (or cooled), fast flowing plasma. Fast MHD pulses (such as solitons) could best describe the dynamic properties of bullets whereas the presence of a multithermal structure is new.« less

Outer Retinal Tubulation in Degenerative Retinal Disorders

PubMed Central

Goldberg, Naomi R.; Greenberg, Jonathan P.; Laud, Ketan; Tsang, Stephen; Freund, K. Bailey

2013-01-01

Objective To demonstrate outer retinal tubulation (ORT) in various degenerative retinal disorders. Methods This was a retrospective review of the multimodal imaging of 29 eyes of 15 patients with various retinal dystrophies and inflammatory maculopathies manifesting ORT. The morphologic features of ORT and its evolution over time were analyzed using spectral-domain optical coherence tomography (SD-OCT) data. Results Outer retinal tubulation was identified as round or ovoid structures with hyper-reflective borders in pattern dystrophy (6 eyes), acute zonal occult outer retinopathy (5 eyes), retinitis pigmentosa (4 eyes), Stargardt disease (4 eyes), gyrate atrophy (2 eyes), choroideremia (2 eyes), and various other degenerative conditions. These structures appeared to develop from the invagination of photoreceptors at the junction of intact and atrophic outer retina. During follow-up, the number and distribution of ORT largely remained stable. As zones of atrophy enlarged, the frequency of ORT appeared to increase. The ORT structures were found in fewer than 10% of patients with retinitis pigmentosa, Stargardt, or pattern dystrophy. Conclusion Outer retinal tubulation is found in various degenerative retinal disorders that share in common damage to the outer retina and/or retinal pigment epithelium. The presence of ORT may be in an indicator of underlying disease stage and severity. PMID:23676993

Thermal Protection System with Staggered Joints

NASA Technical Reports Server (NTRS)

Simon, Xavier D. (Inventor); Robinson, Michael J. (Inventor); Andrews, Thomas L. (Inventor)

2014-01-01

The thermal protection system disclosed herein is suitable for use with a spacecraft such as a reentry module or vehicle, where the spacecraft has a convex surface to be protected. An embodiment of the thermal protection system includes a plurality of heat resistant panels, each having an outer surface configured for exposure to atmosphere, an inner surface opposite the outer surface and configured for attachment to the convex surface of the spacecraft, and a joint edge defined between the outer surface and the inner surface. The joint edges of adjacent ones of the heat resistant panels are configured to mate with each other to form staggered joints that run between the peak of the convex surface and the base section of the convex surface.

Polarimetry Of Planetary Atmospheres: From The Solar System Gas Giants To Extrasolar Planets

NASA Astrophysics Data System (ADS)

Buenzli, Esther; Bazzon, A.; Schmid, H. M.

2011-09-01

The polarization of light reflected from a planet provides unique information on the atmosphere structure and scattering properties of particles in the upper atmosphere. The solar system planets show a large variety of atmospheric polarization properties, from the thick, highly polarizing haze on Titan and the poles of Jupiter, Rayleigh scattering by molecules on Uranus and Neptune, to clouds in the equatorial region of Jupiter or on Venus. Polarimetry is also a promising differential technique to search for and characterize extra-solar planets, e.g. with the future VLT planet finder instrument SPHERE. For the preparation of the SPHERE planet search program we have made a suite of polarimetric observations and models for the solar system gas giants. The phase angles for the outer planets are small for Earth bound observations and the integrated polarization is essentially zero due to the symmetric backscattering situation. However, a second order scattering effect produces a measurable limb polarization for resolved planetary disks. We have made a detailed model for the spectropolarimetric signal of the limb polarization of Uranus between 520 and 935 nm to derive scattering properties of haze and cloud particles and to predict the polarization signal from an extra-solar point of view. We are also investigating imaging polarimetry of the thick haze layers on Titan and the poles of Jupiter. Additionally, we have calculated a large grid of intensity and polarization phase curves for simpler atmosphere models of extrasolar planets.

Efficiency of planetesimal ablation in giant planetary envelopes

NASA Astrophysics Data System (ADS)

Pinhas, Arazi; Madhusudhan, Nikku; Clarke, Cathie

2016-12-01

Observations of exoplanetary spectra are leading to unprecedented constraints on their atmospheric elemental abundances, particularly O/H, C/H, and C/O ratios. Recent studies suggest that elemental ratios could provide important constraints on formation and migration mechanisms of giant exoplanets. A fundamental assumption in such studies is that the chemical composition of the planetary envelope represents the sum-total of compositions of the accreted gas and solids during the formation history of the planet. We investigate the efficiency with which accreted planetesimals ablate in a giant planetary envelope thereby contributing to its composition rather than sinking to the core. From considerations of aerodynamic drag causing `frictional ablation' and the envelope temperature structure causing `thermal ablation', we compute mass ablations for impacting planetesimals of radii 30 m to 1 km for different compositions (ice to iron) and a wide range of velocities and impact angles, assuming spherical symmetry. Icy impactors are fully ablated in the outer envelope for a wide range of parameters. Even for Fe impactors substantial ablation occurs in the envelope for a wide range of sizes and velocities. For example, iron impactors of sizes below ˜0.5 km and velocities above ˜30 km s-1 are found to ablate by ˜60-80 per cent within the outer envelope at pressures below 103 bar due to frictional ablation alone. For deeper pressures (˜107 bar), substantial ablation happens over a wider range of parameters. Therefore, our exploratory study suggests that atmospheric abundances of volatile elements in giant planets reflect their accretion history during formation.

Exoplanet Meteorology: Characterizing the Atmospheres of Directly Imaged Sub-Stellar Objects

NASA Astrophysics Data System (ADS)

Rajan, Abhijith; Gemini Planet Imager, Extrasolar Planets and Systems Imaging Group

2018-01-01

I study the structure, composition and dynamic evolution of directly imaged exoplanet and brown dwarf atmospheres, using spectrophotometric data collected from a range of ground and space based instrumentation. As part of my dissertation, I led studies exploring the atmospheres of brown dwarfs to search for weather variations, and characterized the near and mid infrared SEDs of imaged exoplanets to estimate their fundamental parameters. To understand the evolution of weather on brown dwarfs we conducted a multi-epoch study monitoring of 4 ultracool, T5 - Y0, brown dwarfs in the J-band to search for photometric variability. These cool brown dwarfs are predicted to have salt and sulfide clouds condensing in their upper atmosphere. The study found that cool brown dwarfs, fit with higher opacity clouds, were more likely to be variable. Through data taken with the Hubble Space Telescope and Gemini telescope we characterized the atmospheres of directly imaged exoplanets. For HR 8799, in near IR wavelengths unobservable from the ground, we constrained the presence of clouds in the outer planets. As a member of the Gemini Planet Imager Exoplanet Survey team, I analyzed archival HST data and examined the near-infrared colors of HD 106906b as seen with GPI, concluding that the companion shows weak evidence of a circumplanetary dust disk or cloud. Finally, by combining data spanning 1 - 5 um for the low mass Jupiter-like exoplanet, 51 Eri b, we found a cool effective temperature best fit by a patchy cloud atmosphere. This makes the planet an excellent candidate for future variability studies with the James Webb Space Telescope.

Steamworlds: Atmospheric Structure and Critical Mass of Planets Accreting Icy Pebbles

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

Chambers, John, E-mail: jchambers@carnegiescience.edu

In the core accretion model, gas-giant planets first form a solid core, which then accretes gas from a protoplanetary disk when the core exceeds a critical mass. Here, we model the atmosphere of a core that grows by accreting ice-rich pebbles. The ice fraction of pebbles evaporates in warm regions of the atmosphere, saturating it with water vapor. Excess water precipitates to lower altitudes. Beneath an outer radiative region, the atmosphere is convective, following a moist adiabat in saturated regions due to water condensation and precipitation. Atmospheric mass, density, and temperature increase with core mass. For nominal model parameters, planetsmore » with core masses (ice + rock) between 0.08 and 0.16 Earth masses have surface temperatures between 273 and 647 K and form an ocean. In more massive planets, water exists as a supercritical convecting fluid mixed with gas from the disk. Typically, the core mass reaches a maximum (the critical mass) as a function of the total mass when the core is 2–5 Earth masses. The critical mass depends in a complicated way on pebble size, mass flux, and dust opacity due to the occasional appearance of multiple core-mass maxima. The core mass for an atmosphere of 50% hydrogen and helium may be a more robust indicator of the onset of gas accretion. This mass is typically 1–3 Earth masses for pebbles that are 50% ice by mass, increasing with opacity and pebble flux and decreasing with pebble ice/rock ratio.« less

Imaging spectroscopy of solar radio burst fine structures.

PubMed

Kontar, E P; Yu, S; Kuznetsov, A A; Emslie, A G; Alcock, B; Jeffrey, N L S; Melnik, V N; Bian, N H; Subramanian, P

2017-11-15

Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio wave propagation has long been a major challenge in solar physics. Here we report quantitative spatial and frequency characterization of solar radio burst fine structures observed with the Low Frequency Array, an instrument with high-time resolution that also permits imaging at scales much shorter than those corresponding to radio wave propagation in the corona. The observations demonstrate that radio wave propagation effects, and not the properties of the intrinsic emission source, dominate the observed spatial characteristics of radio burst images. These results permit more accurate estimates of source brightness temperatures, and open opportunities for quantitative study of the mechanisms that create the turbulent coronal medium through which the emitted radiation propagates.

Open cycle ocean thermal energy conversion system

DOEpatents

Wittig, J. Michael

1980-01-01

An improved open cycle ocean thermal energy conversion system including a flash evaporator for vaporizing relatively warm ocean surface water and an axial flow, elastic fluid turbine having a vertical shaft and axis of rotation. The warm ocean water is transmitted to the evaporator through a first prestressed concrete skirt-conduit structure circumferentially situated about the axis of rotation. The unflashed warm ocean water exits the evaporator through a second prestressed concrete skirt-conduit structure located circumferentially about and radially within the first skirt-conduit structure. The radially inner surface of the second skirt conduit structure constitutes a cylinder which functions as the turbine's outer casing and obviates the need for a conventional outer housing. The turbine includes a radially enlarged disc element attached to the shaft for supporting at least one axial row of radially directed blades through which the steam is expanded. A prestressed concrete inner casing structure of the turbine has upstream and downstream portions respectively situated upstream and downstream from the disc element. The radially outer surfaces of the inner casing portions and radially outer periphery of the axially interposed disc cooperatively form a downwardly radially inwardly tapered surface. An annular steam flowpath of increasing flow area in the downward axial direction is radially bounded by the inner and outer prestressed concrete casing structures. The inner casing portions each include a transversely situated prestressed concrete circular wall for rotatably supporting the turbine shaft and associated structure. The turbine blades are substantially radially coextensive with the steam flowpath and receive steam from the evaporator through an annular array of prestressed concrete stationary vanes which extend between the inner and outer casings to provide structural support therefor and impart a desired flow direction to the steam.

Visible and Near-IR Imaging of Giant Planets: Outer Manifestations of Deeper Secrets

NASA Astrophysics Data System (ADS)

Hammel, Heidi B.

1996-09-01

Visible and near-infrared imaging of the giant planets -- Jupiter, Saturn, Uranus, and Neptune -- probes the outermost layers of clouds in these gaseous atmospheres. Not only are the images beautiful and striking in their color and diversity of detail, they also provide quantitative clues to the dynamical and chemical processes taking place both at the cloud tops and deeper in the interior: zonal wind profiles can be extracted; wavelength-dependent center-to-limb brightness variations yield valuable data for modeling vertical aerosol structure; the presence of planetary-scale atmospheric waves can sometimes be deduced; variations of cloud color and brightness with latitude provide insight into the underlying mechanisms driving circulation; development and evolution of discrete atmospheric features trace both exogenic and endogenic events. During the 1980's, our understanding of the giant planets was revolutionized by detailed visible-wavelength images taken by the Voyager spacecraft of these planets' atmospheres. However, those images were static: brief snapshots in time of four complex and dynamic atmospheric systems. In short, those images no longer represent the current appearance of these planets. Recently, our knowledge of the atmospheres of the gas giant planets has undergone major new advances, due in part to the excellent imaging capability and longer-term temporal sampling of the Hubble Space Telescope (HST) and the Galileo Mission to Jupiter. In this talk, I provide an update on our current understanding of the gas giants based on recent visible and near-infrared imaging, highlighting results from the collision of Comet Shoemaker-Levy 9 with Jupiter, Saturn's White Spots, intriguing changes in the atmosphere of Uranus, and Neptune's peripatetic clouds.

46 CFR 154.170 - Outer hull steel plating.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the outer hull steel plating, including the shell and deck plating must meet the material standards of the... 46 Shipping 5 2014-10-01 2014-10-01 false Outer hull steel plating. 154.170 Section 154.170...

46 CFR 154.170 - Outer hull steel plating.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the outer hull steel plating, including the shell and deck plating must meet the material standards of the... 46 Shipping 5 2012-10-01 2012-10-01 false Outer hull steel plating. 154.170 Section 154.170...

46 CFR 154.170 - Outer hull steel plating.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the outer hull steel plating, including the shell and deck plating must meet the material standards of the... 46 Shipping 5 2013-10-01 2013-10-01 false Outer hull steel plating. 154.170 Section 154.170...

15 CFR 930.81 - Multiple permit review.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL RESOURCE MANAGEMENT FEDERAL CONSISTENCY WITH APPROVED COASTAL MANAGEMENT PROGRAMS Consistency for Outer Continental... applicable to OCS-related federal license or permit activities affecting any coastal use or resource which...

15 CFR 930.81 - Multiple permit review.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL RESOURCE MANAGEMENT FEDERAL CONSISTENCY WITH APPROVED COASTAL MANAGEMENT PROGRAMS Consistency for Outer Continental... applicable to OCS-related federal license or permit activities affecting any coastal use or resource which...

15 CFR 930.81 - Multiple permit review.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL RESOURCE MANAGEMENT FEDERAL CONSISTENCY WITH APPROVED COASTAL MANAGEMENT PROGRAMS Consistency for Outer Continental... applicable to OCS-related federal license or permit activities affecting any coastal use or resource which...

15 CFR 930.81 - Multiple permit review.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL RESOURCE MANAGEMENT FEDERAL CONSISTENCY WITH APPROVED COASTAL MANAGEMENT PROGRAMS Consistency for Outer Continental... applicable to OCS-related federal license or permit activities affecting any coastal use or resource which...

15 CFR 930.81 - Multiple permit review.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL RESOURCE MANAGEMENT FEDERAL CONSISTENCY WITH APPROVED COASTAL MANAGEMENT PROGRAMS Consistency for Outer Continental... applicable to OCS-related federal license or permit activities affecting any coastal use or resource which...

Optimization of a Hot Structure Aeroshell and Nose Cap for Mars Atmospheric Entry

NASA Technical Reports Server (NTRS)

Langston, Sarah L.; Lang, Christapher G.; Samareh, Jamshid A.; Daryabeigi, Kamran

2016-01-01

The National Aeronautics and Space Administration (NASA) is preparing to send humans beyond Low Earth Orbit and eventually to the surface of Mars. As part of the Evolvable Mars Campaign, different vehicle configurations are being designed and considered for delivering large payloads to the surface of Mars. Weight and packing volume are driving factors in the vehicle design, and the thermal protection system (TPS) for planetary entry is a technology area which can offer potential weight and volume savings. The feasibility and potential benefits of a ceramic matrix composite hot structure concept for different vehicle configurations are explored in this paper, including the nose cap for a Hypersonic Inflatable Aerodynamic Decelerator (HIAD) and an aeroshell for a mid lift-to-drag (Mid L/D) concept. The TPS of a planetary entry vehicle is a critical component required to survive the severe aerodynamic heating environment during atmospheric en- try. The current state-of-the-art is an ablative material to protect the vehicle from the heat load. The ablator is bonded to an underlying structure, which carries the mechanical loads associated with entry. The alternative hot structure design utilizes an advanced carbon-carbon material system on the outer surface of the vehicle, which is exposed to the severe heating and acts as a load carrying structure. The preliminary design using the hot structure concept and the ablative concept is determined for the spherical nose cap of the HIAD entry vehicle and the aeroshell of the Mid L/D entry vehicle. The results of the study indicate that the use of hot structures for both vehicle concepts leads to a feasible design with potential weight and volume savings benefits over current state-of-the-art TPS technology that could enable future missions.

Turbine airfoil with a compliant outer wall

DOEpatents

Campbell, Christian X [Oviedo, FL; Morrison, Jay A [Oviedo, FL

2012-04-03

A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation in the outer layer is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a support structure. The outer layer may be a compliant layer configured such that the outer layer may thermally expand and thereby reduce the stress within the outer layer. The outer layer may be formed from a nonplanar surface configured to thermally expand. In another embodiment, the outer layer may be planar and include a plurality of slots enabling unrestricted thermal expansion in a direction aligned with the outer layer.

Saturn/Titan Rendezvous: A Solar-Sail Aerocapture Mission

NASA Technical Reports Server (NTRS)

Matloff, Gregory L.; Taylor, Travis; Powell, Conley

2004-01-01

A low-mass Titan orbiter is proposed that uses conservative or optimistic solar sails for all post-Earth-escape propulsion. After accelerating the probe onto a trans-Saturn trajectory, the sail is used parachute style for Saturn capture during a pass through Saturn's outer atmosphere. If the apoapsis of the Saturn-capture orbit is appropriate, the aerocapture maneuver can later be repeated at Titan so that the spacecraft becomes a satellite of Titan. An isodensity-atmosphere model is applied to screen aerocapture trajectories. Huygens/Cassini should greatly reduce uncertainties regarding the upper atmospheres of Saturn and Titan.

Engineering-Level Model Atmospheres for Titan and Neptune

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta; Johnson, D. L.

2003-01-01

Engineering-level atmospheric models for Titan and Neptune have been developed for use in NASA s systems analysis studies of aerocapture applications in missions to the outer planets. Analogous to highly successful Global Reference Atmospheric Models for Earth (GRAM, Justus et al., 2000) and Mars (Mars-GRAM, Justus and Johnson, 2001, Justus et al., 2002) the new models are called Titan-GRAM and Neptune-GRAM. Like GRAM and Mars-GRAM, an important feature of Titan-GRAM and Neptune-GRAM is their ability to simulate quasi-random perturbations for Monte- Carlo analyses in developing guidance, navigation and control algorithms, and for thermal systems design.

Lightweight Thermal Protection System for Atmospheric Entry

NASA Technical Reports Server (NTRS)

Stewart, David; Leiser, Daniel

2007-01-01

TUFROC (Toughened Uni-piece Fibrous Reinforced Oxidation-resistant Composite) has been developed as a new thermal protection system (TPS) material for wing leading edge and nose cap applications. The composite withstands temperatures up to 1,970 K, and consists of a toughened, high-temperature surface cap and a low-thermal-conductivity base, and is applicable to both sharp and blunt leading edge vehicles. This extends the possible application of fibrous insulation to the wing leading edge and/or nose cap on a hypersonic vehicle. The lightweight system comprises a treated carbonaceous cap composed of ROCCI (Refractory Oxidation-resistant Ceramic Carbon Insulation), which provides dimensional stability to the outer mold line, while the fibrous base material provides maximum thermal insulation for the vehicle structure.

Carbon phenolic heat shields for Jupiter/Saturn/Uranus entry probes

NASA Technical Reports Server (NTRS)

Mezines, S.

1974-01-01

Carbon phenolic heat shield technology is reviewed. Heat shield results from the outer planetary probe mission studies are summarized along with results of plasma jet testing of carbon phenolic conducted in a ten megawatt facility. Missile flight data is applied to planetary entry conditions. A carbon phenolic heat shield material is utilized and tailored to accommodate each of the probe missions. An integral heat shield approach is selected over in order to eliminate a high temperature interface problem and permit direct bonding of the carbon phenolic to the structural honeycomb sandwich. The sandwich is filled with a very fine powder to minimize degradation of its insulation properties by the high conductive hydrogen/helium gases during the long atmospheric descent phase.

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

Spatially resolving the outer atmosphere of the M giant BK Virginis in the CO first overtone lines with VLTI/AMBER

NASA Astrophysics Data System (ADS)

Ohnaka, K.; Hofmann, K.-H.; Schertl, D.; Weigelt, G.; Malbet, F.; Massi, F.; Meilland, A.; Stee, Ph.

2012-01-01

Context. The mass-loss mechanism in normal K-M giant stars with small variability amplitudes is not yet understood, although the majority among red giant stars are precisely of this type. Aims: We present high-spatial and high-spectral resolution observations of the M7 giant BK Vir with AMBER at the Very Large Telescope Interferometer (VLTI). Our aim is to probe the physical properties of the outer atmosphere by spatially resolving the star in the individual CO first overtone lines. Methods: BK Vir was observed between 2.26 and 2.31 μm using the 16-32-48 m telescope configuration with an angular resolution of 9.8 mas and a spectral resolution of 12 000. Results: The uniform-disk diameters observed in the CO first overtone lines are 12 - 31% larger than those measured in the continuum. We also detected asymmetry in the CO line-forming region, which manifests itself as non-zero/non-π differential and closure phases. The data taken 1.5 months apart show possible time variation on a spatial scale of 30 mas (corresponding to 3 × stellar diameter) at the CO band head. Comparison of the observed data with the MARCS photospheric model shows that whereas the observed CO line spectrum can be satisfactorily reproduced by the model, the angular sizes observed in the CO lines are much larger than predicted by the model. Our model with two additional CO layers above the MARCS photosphere reproduces the observed spectrum and interferometric data in the CO lines simultaneously. This model suggests that the inner CO layer at ~1.2 R⋆ is very dense and warm with a CO column density of ~1022 cm-2 and temperatures of 1900 - 2100 K, while the outer CO layer at 2.5-3.0 R⋆ is characterized by column densities of 1019-1020 cm-2 and temperatures of 1500 - 2100 K. Conclusions: Our AMBER observations of BK Vir have spatially resolved the extended molecular outer atmosphere of a normal M giant in the individual CO lines for the first time. The temperatures derived for the CO layers are higher than, or equal to, the uppermost layer of the MARCS photospheric model, implying the operation of some heating mechanism in the outer atmosphere. This study also illustrates that testing photospheric models only with the spectra of strong molecular or atomic features can be misleading. Based on AMBER observations made with the Very Large Telescope Interferometer of the European Southern Observatory. Program ID: 081.D-0233(A) (AMBER Guaranteed Time Observation).

The evolution of forearc structures along an oblique convergent margin, central Aleutian Arc

USGS Publications Warehouse

Ryan, H.F.; Scholl, D. W.

1989-01-01

Multichannel seismic reflection data were used to determine the evolutionary history of the forearc region of the central Aleutian Ridge. Since at least late Miocene time this sector of the ridge has been obliquely underthrust 30?? west of orthogonal convergence by the northwestward converging Pacific plate at a rate of 80-90 km/m.y. Our data indicate that prior to late Eocene time the forearc region was composed of rocks of the arc massif thinly mantled by slope deposits. Beginning in latest Miocene or earliest Pliocene time, a zone of outer-arc structural highs and a forearc basin began to form. Initial structures of the zone of outer-arc highs formed as the thickening wedge underran, compressively deformed, and uplifted the seaward edge of the arc massive above a landward dipping backstop thrust. Forearc basin strata ponded arcward of the elevating zone of outer-arc highs. However, most younger structures of the zone of outer-arc highs cannot be ascribed simply to the orthogonal effects of an underrunning wedge. Oblique convergence created a major right-lateral shear zone (the Hawley Ridge shear zone) that longitudinally disrupted the zone of outer-arc highs, truncating the seaward flank of the forearc basin and shearing the southern limb of Hawley Ridge, an exceptionally large antiformal outer-arc high structure. Uplift of Hawley Ridge may be related to the thickening of the arc massif by westward directed basement duplexes. Great structural complexity, including the close juxtaposition of coeval structures recording compression, extension, differential vertical movements, and strike-slip displacement, should be expected, even within areas of generally kindred tectonostratigraphic terranes. -from Authors

A CCD comparison of outer Jovian satellites and Trojan asteroids

NASA Technical Reports Server (NTRS)

Luu, Jane X.

1991-01-01

The eight small outer Jovian satellites are not as well known as the brighter, more illustrious Galilean satellites. They are divided into two groups, each containing four satellites; the inner group travels in prograde orbits while the outer group travels in retrograde orbits. From the distinct orbital characteristics of the two groups, most of the theories of their origin involve the capture and breakup of two planetesimals upon entry into the atmosphere of proto-Jupiter. Their proximity to the Trojans asteroids has led to conjectures of a link between them and the Trojans. However, Tholen and Zellner (1984) found no red spectrum among six of the satellites and postulated that they were all C-type objects; therefore, they were unlikely to be derivatives of the Trojan population. Charge-coupled device (CCD) photometry and spectroscopy of the eight outer Jovian satellites obtained from 1987 to 1989 and a comparison between these eight satellites and the Trojan asteroids are presented.

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.

Earth's Outer Core Properties Estimated Using Bayesian Inversion of Normal Mode Eigenfrequencies

NASA Astrophysics Data System (ADS)

Irving, J. C. E.; Cottaar, S.; Lekic, V.

2016-12-01

The outer core is arguably Earth's most dynamic region, and consists of an iron-nickel liquid with an unknown combination of lighter alloying elements. Frequencies of Earth's normal modes provide the strongest constraints on the radial profiles of compressional wavespeed, VΦ, and density, ρ, in the outer core. Recent great earthquakes have yielded new normal mode measurements; however, mineral physics experiments and calculations are often compared to the Preliminary reference Earth model (PREM), which is 35 years old and does not provide uncertainties. Here we investigate the thermo-elastic properties of the outer core using Earth's free oscillations and a Bayesian framework. To estimate radial structure of the outer core and its uncertainties, we choose to exploit recent datasets of normal mode centre frequencies. Under the self-coupling approximation, centre frequencies are unaffected by lateral heterogeneities in the Earth, for example in the mantle. Normal modes are sensitive to both VΦ and ρ in the outer core, with each mode's specific sensitivity depending on its eigenfunctions. We include a priori bounds on outer core models that ensure compatibility with measurements of mass and moment of inertia. We use Bayesian Monte Carlo Markov Chain techniques to explore different choices in parameterizing the outer core, each of which represents different a priori constraints. We test how results vary (1) assuming a smooth polynomial parametrization, (2) allowing for structure close to the outer core's boundaries, (3) assuming an Equation-of-State and adiabaticity and inverting directly for thermo-elastic parameters. In the second approach we recognize that the outer core may have distinct regions close to the core-mantle and inner core boundaries and investigate models which parameterize the well mixed outer core separately from these two layers. In the last approach we seek to map the uncertainties directly into thermo-elastic parameters including the bulk modulus, its pressure derivative, and molar mass and volume, with particular attention paid to the (inherent) trade-offs between the different coefficients. We discuss our results in terms of added uncertainty to the light element composition of the outer core and the potential existence of anomalous structure near the outer core's boundaries.

Deuterium Labeling Strategies for Creating Contrast in Structure-Function Studies of Model Bacterial Outer Membranes Using Neutron Reflectometry.

PubMed

Le Brun, Anton P; Clifton, Luke A; Holt, Stephen A; Holden, Peter J; Lakey, Jeremy H

2016-01-01

Studying the outer membrane of Gram-negative bacteria is challenging due to the complex nature of its structure. Therefore, simplified models are required to undertake structure-function studies of processes that occur at the outer membrane/fluid interface. Model membranes can be created by immobilizing bilayers to solid supports such as gold or silicon surfaces, or as monolayers on a liquid support where the surface pressure and fluidity of the lipids can be controlled. Both model systems are amenable to having their structure probed by neutron reflectometry, a technique that provides a one-dimensional depth profile through a membrane detailing its thickness and composition. One of the strengths of neutron scattering is the ability to use contrast matching, allowing molecules containing hydrogen and those enriched with deuterium to be highlighted or matched out against the bulk isotopic composition of the solvent. Lipopolysaccharides, a major component of the outer membrane, can be isolated for incorporation into model membranes. Here, we describe the deuteration of lipopolysaccharides from rough strains of Escherichia coli for incorporation into model outer membranes, and how the use of deuterated materials enhances structural analysis of model membranes by neutron reflectometry. © 2016 Elsevier Inc. All rights reserved.

Photochemical Modeling of CH3 Abundances in the Outer Solar System

NASA Technical Reports Server (NTRS)

Lee, Anthony Y. T.; Yung, Yuk L.; Moses, Julianne

2000-01-01

Recent measurements of methyl radicals (CH3) in the upper atmospheres of Saturn and Neptune by the Infrared Space Observatory (ISO) provide new constraints to photochemical models of hydrocarbon chemistry in the outer solar system. The derived column abundances of CH3 on Saturn above 10 mbar and Neptune above the 0.2 mbar pressure level are (2.5 - 6.0) x 10(exp 13) / sq cm and (0.7 - 2.8) x 10(exp 13) / sq cm, respectively. We use the updated Caltech/Jet Propulsion Laboratory photochemical model, which incorporates hydrocarbon photochemistry, vertical molecular and bulk atmospheric eddy diffusion, and realistic radiative transfer modeling, to study the CH3 abundances in the upper atmosphere of the giant planets and Titan. We identify the key reactions that control the concentrations of CH3 in the model, such as the three-body recombination reaction, CH3 + CH3 + M yields C2H6 + M. We evaluate and extrapolate the three-body rate constant of this reaction to the low-temperature limit (1.8 x 10(exp -16) T(sup -3.75) e(sup -300/T), T < 300 K) and compare methyl radical abundances in five atmospheres: Jupiter, Saturn, Uranus, Neptune, and Titan. The sensitivity of our models to the rate coefficients for the reactions H + CH3 + M yields CH4 + M, H + C2H3 yields C2H2 + H2, (sup 1)CH2 + H2 yields CH3 + H, and H + C2H5 yields 2CH3, the branching ratios of CH4 photolysis, vertical mixing in the five atmospheres, and Lyman alpha photon enhancement at the orbit of Neptune have all been tested. The results of our model CH3 abundances for both Saturn (5.1 x 10(exp 13) / sq cm) and Neptune (2.2 x 10(exp 13) / sq cm) show good agreement with ISO Short Wavelength Spectrometer measurements. Using the same chemical reaction set, our calculations also successfully generate vertical profiles of stable hydrocarbons consistent with Voyager and ground-based measurements in these outer solar system atmospheres. Predictions of CH3 column concentrations (for p <= 0.2 mbar) in the atmospheres of Jupiter (3.3 x 10(exp 13) /sq cm), Uranus (2.5 x 10(exp 12) / sq cm), and Titan (1.9 x 10(exp 15) / sq cm) may be checked by future observations.

Phase Behaviour of Methane Hydrate Under Conditions Relevant to Titan's Interior

NASA Astrophysics Data System (ADS)

Sclater, G.; Fortes, A. D.; Crawford, I. A.

2018-06-01

The high-pressure behaviour Clathrate hydrates, thought to be abundant in the outer solar system, underpins planetary modelling efforts of the interior of Titan, where clathrates are hypothesised to be the source of the dense N2, CH4 atmosphere.

Scientific rationale for Uranus and Neptune in situ explorations

NASA Astrophysics Data System (ADS)

Mousis, O.; Atkinson, D. H.; Cavalié, T.; Fletcher, L. N.; Amato, M. J.; Aslam, S.; Ferri, F.; Renard, J.-B.; Spilker, T.; Venkatapathy, E.; Wurz, P.; Aplin, K.; Coustenis, A.; Deleuil, M.; Dobrijevic, M.; Fouchet, T.; Guillot, T.; Hartogh, P.; Hewagama, T.; Hofstadter, M. D.; Hue, V.; Hueso, R.; Lebreton, J.-P.; Lellouch, E.; Moses, J.; Orton, G. S.; Pearl, J. C.; Sánchez-Lavega, A.; Simon, A.; Venot, O.; Waite, J. H.; Achterberg, R. K.; Atreya, S.; Billebaud, F.; Blanc, M.; Borget, F.; Brugger, B.; Charnoz, S.; Chiavassa, T.; Cottini, V.; d'Hendecourt, L.; Danger, G.; Encrenaz, T.; Gorius, N. J. P.; Jorda, L.; Marty, B.; Moreno, R.; Morse, A.; Nixon, C.; Reh, K.; Ronnet, T.; Schmider, F.-X.; Sheridan, S.; Sotin, C.; Vernazza, P.; Villanueva, G. L.

2018-06-01

The ice giants Uranus and Neptune are the least understood class of planets in our solar system but the most frequently observed type of exoplanets. Presumed to have a small rocky core, a deep interior comprising ∼70% heavy elements surrounded by a more dilute outer envelope of H2 and He, Uranus and Neptune are fundamentally different from the better-explored gas giants Jupiter and Saturn. Because of the lack of dedicated exploration missions, our knowledge of the composition and atmospheric processes of these distant worlds is primarily derived from remote sensing from Earth-based observatories and space telescopes. As a result, Uranus's and Neptune's physical and atmospheric properties remain poorly constrained and their roles in the evolution of the Solar System not well understood. Exploration of an ice giant system is therefore a high-priority science objective as these systems (including the magnetosphere, satellites, rings, atmosphere, and interior) challenge our understanding of planetary formation and evolution. Here we describe the main scientific goals to be addressed by a future in situ exploration of an ice giant. An atmospheric entry probe targeting the 10-bar level, about 5 scale heights beneath the tropopause, would yield insight into two broad themes: i) the formation history of the ice giants and, in a broader extent, that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. In addition, possible mission concepts and partnerships are presented, and a strawman ice-giant probe payload is described. An ice-giant atmospheric probe could represent a significant ESA contribution to a future NASA ice-giant flagship mission.

Extended atmospheres of outer planet satellites and comets

NASA Technical Reports Server (NTRS)

Smyth, William H.; Combi, Michael R.

1988-01-01

In the third year of this 3-year project, research accomplishments are discussed and related to the overall objective. In the area of the distribution of hydrogen in the Saturn system, new Voyager UVS data have been discovered and are discussed. The data suggest that both Titan's hydrogen torus and Saturn's hydrogen corona play a major role in the circumplanetary gas source. Modeling analysis of this new data establishes a strong basis for continuing studies to be undertaken in a new NASA-sponsored project. In the area of the cometary atmospheres, observational data for H, O, C, and OH acquired with the Pioneer Venus Orbiter are evaluated and preliminary modeling analysis for some of the hydrogen Lyman-alpha data is presented. In addition, the importance of collisional thermalization in spatial properties and structure of the inner and extended comae of comets has been demonstrated using the recently developed particle trajectory model. The successful simulation by this model of the hydrogen Lyman-alpha image for Comet Kohoutec near perihelion, an extreme case for collisional thermalization, is particularly noteworthy.

Atmospheric propagation at larger lateral distances from the flight track

NASA Technical Reports Server (NTRS)

Pierce, Allan D.

1994-01-01

Sonic booms received on the ground tend to be restricted to a region of finite lateral extent below the flight track. This occurs because of refraction and because the effective speed of sound, even with winds taken into account, decreases with altitude in the lower atmosphere. Not all rays proceeding initially downwards from the flight track within an allowable range of initial directions will reach the ground. The restricted region which can be reached by rays impacting the ground is known as the primary carpet. However, weak rumbles are heard in the nominal shadow zone beyond the edge of this carpet. A full wave theory is necessary for explaining waveforms in that region, and the present paper gives a matched asymptotic expansion technique for a suitable approximate full wave theory that involves a relatively small number of parameters. The outer solution is derived from the structure of the system of rays that impact near the corridor edge; the inner solution involves a solution of the parabolic equation and results in the special functions encountered in the diffraction of sound over the tops of hills.

Eddy Current for Sizing Cracks in Canisters for Dry Storage of Used Nuclear Fuel

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

Meyer, Ryan M.; Jones, Anthony M.; Pardini, Allan F.

2014-01-01

The storage of used nuclear fuel (UNF) in dry canister storage systems (DCSSs) at Independent Spent Fuel Storage Installations (ISFSI) sites is a temporary measure to accommodate UNF inventory until it can be reprocessed or transferred to a repository for permanent disposal. Policy uncertainty surrounding the long-term management of UNF indicates that DCSSs will need to store UNF for much longer periods than originally envisioned. Meanwhile, the structural and leak-tight integrity of DCSSs must not be compromised. The eddy current technique is presented as a potential tool for inspecting the outer surfaces of DCSS canisters for degradation, particularly atmospheric stressmore » corrosion cracking (SCC). Results are presented that demonstrate that eddy current can detect flaws that cannot be detected reliably using standard visual techniques. In addition, simulations are performed to explore the best parameters of a pancake coil probe for sizing of SCC flaws in DCSS canisters and to identify features in frequency sweep curves that may potentially be useful for facilitating accurate depth sizing of atmospheric SCC flaws from eddy current measurements.« less

Aerocapture Technology Development Needs for Outer Planet Exploration

NASA Technical Reports Server (NTRS)

Wercinski, Paul; Munk, Michelle; Powell, Richard; Hall, Jeff; Graves, Claude; Partridge, Harry (Technical Monitor)

2002-01-01

The purpose of this white paper is to identify aerocapture technology and system level development needs to enable NASA future mission planning to support Outer Planet Exploration. Aerocapture is a flight maneuver that takes place at very high speeds within a planet's atmosphere that provides a change in velocity using aerodynamic forces (in contrast to propulsive thrust) for orbit insertion. Aerocapture is very much a system level technology where individual disciplines such as system analysis and integrated vehicle design, aerodynamics, aerothermal environments, thermal protection systems (TPS), guidance, navigation and control (GN&C) instrumentation need to be integrated and optimized to meet mission specific requirements. This paper identifies on-going activities, their relevance and potential benefit to outer planet aerocapture that include New Millennium ST7 Aerocapture concept definition study, Mars Exploration Program aeroassist project level support, and FY01 Aeroassist In-Space Guideline tasks. The challenges of performing aerocapture for outer planet missions such as Titan Explorer or Neptune Orbiter require investments to advance the technology readiness of the aerocapture technology disciplines for the unique application of outer planet aerocapture. This white paper will identify critical technology gaps (with emphasis on aeroshell concepts) and strategies for advancement.

Organic matter in the Saturn system

NASA Technical Reports Server (NTRS)

Sagan, C.; Khare, B. N.; Lewis, J. S.

1984-01-01

Theoretical and experimental predictions of the formation (and outgassing) of organic molecules in the outer solar system are compared with Voyager IRIS spectral data for the Titan atmosphere. The organic molecules of Titan are of interest because the species and processes within the atmosphere of that moon may have had analogs in the early earth atmosphere 4 Gyr ago. The spacecraft data confirmed the presence of alkanes, ethane, propane, ethylene, alkynes, acetylene, butadiene, methylacetylene, nitriles, hydrogen cyanide, cyanoacetylene, and cyanogen, all heavier than the dominant CH4. Experimental simulation of the effects of UV photolysis, alpha and gamma ray irradiation, electrical discharges and proton and electron bombardment of similar gas mixtures has shown the best promise for modeling the reactions producing the Titan atmosphere chemicals.

Deviations from LTE in a stellar atmosphere

NASA Technical Reports Server (NTRS)

Kalkofen, W.; Klein, R. I.; Stein, R. F.

1979-01-01

Deviations for LTE are investigated in an atmosphere of hydrogen atoms with one bound level, satisfying the equations of radiative, hydrostatic, and statistical equilibrium. The departure coefficient and the kinetic temperature as functions of the frequency dependence of the radiative cross section are studied analytically and numerically. Near the outer boundary of the atmosphere, the departure coefficient is smaller than unity when the radiative cross section grows with frequency faster than with the square of frequency; it exceeds unity otherwise. Far from the boundary the departure coefficient tends to exceed unity for any frequency dependence of the radiative cross section. Overpopulation always implies that the kinetic temperature in the statistical-equilibrium atmosphere is higher than the temperature in the corresponding LTE atmosphere. Upper and lower bounds on the kinetic temperature are given for an atmosphere with deviations from LTE only in the optically shallow layers when the emergent intensity can be described by a radiation temperature.

Energetic particle influences in Earth's atmosphere

NASA Astrophysics Data System (ADS)

Aplin, Karen; Harrison, R. Giles; Nicoll, Keri; Rycroft, Michael; Briggs, Aaron

2016-04-01

Energetic particles from outer space, known as galactic cosmic rays, constantly ionise the entire atmosphere. During strong solar storms, solar energetic particles can also reach the troposphere and enhance ionisation. Atmospheric ionisation generates cluster ions. These facilitate current flow in the global electric circuit, which arises from charge separation in thunderstorms driven by meteorological processes. Energetic particles, whether solar or galactic in origin, may influence the troposphere and stratosphere through a range of different mechanisms, each probably contributing a small amount. Some of the suggested processes potentially acting over a wide spatial area in the troposphere include enhanced scavenging of charged aerosol particles, modification of droplet or droplet-droplet behavior by charging, and the direct absorption of infra-red radiation by the bending and stretching of hydrogen bonds inside atmospheric cluster-ions. As well as reviewing the proposed mechanisms by which energetic particles modulate atmospheric properties, we will also discuss new instrumentation for measurement of energetic particles in the atmosphere.

Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

NASA Technical Reports Server (NTRS)

Nelson, H. F.

1982-01-01

The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiative heating of probes entering the hydrogen-helium atmosphere of the major plants was investigated. Two opposing conclusions were reached as to how the ionization rate assumption affects the radiative transfer. Hydrogen-helium shock waves with a cold nonblowing wall boundary condition at the probe heat shield are emphasized. The study is limited to the stagnation shock layer.

Technology requirements for a generic aerocapture system. [for atmospheric entry

NASA Technical Reports Server (NTRS)

Cruz, M. I.

1980-01-01

The technology requirements for the design of a generic aerocapture vehicle system are summarized. These spacecraft have the capability of completely eliminating fuel-costly retropropulsion for planetary orbit capture through a single aerodynamically controlled atmospheric braking pass from a hyperbolic trajectory into a near circular orbit. This generic system has application at both the inner and outer planets. Spacecraft design integration, navigation, communications, and aerothermal protection system design problems were assessed in the technology requirements study and are discussed in this paper.

First generation atmospheric probes (10-BARS) for Uranus and Neptune

NASA Technical Reports Server (NTRS)

Sullivan, R. J.; Waters, J. I.; Dunkin, J. H.

1972-01-01

The feasibility of atmospheric entry probe missions to Uranus and Neptune is studied, and preliminary estimates of missions parameters are presented. Most of the study results are applicable, with only minor modifications, to Uranus-Neptune entry probes included on any type of outer planet mission. Trajectory dynamics is discussed first because it imposes some important constraints upon the total time available for data transmission, which in turn determines the descent rate. This last quantity provides important information for the design of the scientific payload.

Scintillation index and performance analysis of wireless optical links over non-Kolmogorov weak turbulence based on generalized atmospheric spectral model.

PubMed

Cang, Ji; Liu, Xu

2011-09-26

Based on the generalized spectral model for non-Kolmogorov atmospheric turbulence, analytic expressions of the scintillation index (SI) are derived for plane, spherical optical waves and a partially coherent Gaussian beam propagating through non-Kolmogorov turbulence horizontally in the weak fluctuation regime. The new expressions relate the SI to the finite turbulence inner and outer scales, spatial coherence of the source and spectral power-law and then used to analyze the effects of atmospheric condition and link length on the performance of wireless optical communication links. © 2011 Optical Society of America

Effects of long-term elevated CO 2 treatment on the inner and outer bark chemistry of sweetgum (Liquidambar styraciflua L.) trees

DOE PAGES

Eberhardt, Thomas L.; Labbé, Nicole; So, Chi-Leung; ...

2015-07-23

Long-term exposure of sweetgum trees to elevated atmospheric CO 2 concentrations significantly shifted inner bark (phloem) and outer bark (rhytidome) chemical compositions, having implications for both defense and nutrient cycling. Changes in plant tissue chemistry due to increasing atmospheric carbon dioxide (CO 2) concentrations have direct implications for tissue resistance to abiotic and biotic stress while living, and soil nutrient cycling when senesced as litter. Although the effects of elevated CO 2 concentrations on tree foliar chemistry are well documented, the effects on tree bark chemistry are largely unknown. The objective of our study was to determine the effects ofmore » a long-term elevated CO 2 treatment on the contents of individual elements, extractives, ash, lignin, and polysaccharide sugars of sweetgum (Liquidambar styraciflua L.) bark. Trees were harvested from sweetgum plots equipped with the Free-Air CO 2 Enrichment (FACE) apparatus, receiving either elevated or ambient CO 2 treatments over a 12-year period. Whole bark sections were partitioned into inner bark (phloem) and outer bark (rhytidome) samples before analysis. Moreover, principal component analysis, coupled with either Fourier transform infrared spectroscopy or pyrolysis-gas chromatography-mass spectrometry data, was also used to screen for differences. Elevated CO 2 reduced the N content (0.42 vs. 0.35 %) and increased the C:N ratio (109 vs. 136 %) of the outer bark. For the inner bark, elevated CO 2 increased the Mn content (470 vs. 815 mg kg -1), total extractives (13.0 vs. 15.6 %), and residual ash content (8.1 vs. 10.8 %) as compared to ambient CO 2; differences were also observed for some hemicellulosic sugars, but not lignin. Shifts in bark chemistry can affect the success of herbivores and pathogens in living trees, and as litter, bark can affect the biogeochemical cycling of nutrients within the forest floor. Our results demonstrate that increasing atmospheric CO 2 concentrations have the potential to impact the chemistry of temperate, deciduous tree bark such as sweetgum.« less

Effects of long-term elevated CO 2 treatment on the inner and outer bark chemistry of sweetgum (Liquidambar styraciflua L.) trees

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

Eberhardt, Thomas L.; Labbé, Nicole; So, Chi-Leung

Long-term exposure of sweetgum trees to elevated atmospheric CO 2 concentrations significantly shifted inner bark (phloem) and outer bark (rhytidome) chemical compositions, having implications for both defense and nutrient cycling. Changes in plant tissue chemistry due to increasing atmospheric carbon dioxide (CO 2) concentrations have direct implications for tissue resistance to abiotic and biotic stress while living, and soil nutrient cycling when senesced as litter. Although the effects of elevated CO 2 concentrations on tree foliar chemistry are well documented, the effects on tree bark chemistry are largely unknown. The objective of our study was to determine the effects ofmore » a long-term elevated CO 2 treatment on the contents of individual elements, extractives, ash, lignin, and polysaccharide sugars of sweetgum (Liquidambar styraciflua L.) bark. Trees were harvested from sweetgum plots equipped with the Free-Air CO 2 Enrichment (FACE) apparatus, receiving either elevated or ambient CO 2 treatments over a 12-year period. Whole bark sections were partitioned into inner bark (phloem) and outer bark (rhytidome) samples before analysis. Moreover, principal component analysis, coupled with either Fourier transform infrared spectroscopy or pyrolysis-gas chromatography-mass spectrometry data, was also used to screen for differences. Elevated CO 2 reduced the N content (0.42 vs. 0.35 %) and increased the C:N ratio (109 vs. 136 %) of the outer bark. For the inner bark, elevated CO 2 increased the Mn content (470 vs. 815 mg kg -1), total extractives (13.0 vs. 15.6 %), and residual ash content (8.1 vs. 10.8 %) as compared to ambient CO 2; differences were also observed for some hemicellulosic sugars, but not lignin. Shifts in bark chemistry can affect the success of herbivores and pathogens in living trees, and as litter, bark can affect the biogeochemical cycling of nutrients within the forest floor. Our results demonstrate that increasing atmospheric CO 2 concentrations have the potential to impact the chemistry of temperate, deciduous tree bark such as sweetgum.« less

A Fragment-Cloud Model for Breakup of Asteroids with Varied Internal Structures

NASA Technical Reports Server (NTRS)

Wheeler, Lorien; Mathias, Donovan; Stokan, Ed; Brown, Peter

2016-01-01

As an asteroid descends toward Earth, it deposits energy in the atmosphere through aerodynamic drag and ablation. Asteroid impact risk assessments rely on energy deposition estimates to predict blast overpressures and ground damage that may result from an airburst, such as the one that occurred over Chelyabinsk, Russia in 2013. The rates and altitudes at which energy is deposited along the entry trajectory depend upon how the bolide fragments, which in turn depends upon its internal structure and composition. In this work, we have developed an analytic asteroid fragmentation model to assess the atmospheric energy deposition of asteroids with a range of structures and compositions. The modeling approach combines successive fragmentation of larger independent pieces with aggregate debris clouds released with each fragmentation event. The model can vary the number and masses of fragments produced, the amount of mass released as debris clouds, the size-strength scaling used to increase the robustness of smaller fragments, and other parameters. The initial asteroid body can be seeded with a distribution of independent fragment sizes amid a remaining debris mass to represent loose rubble pile conglomerations, can be given an outer regolith later, or can be defined as a coherent or fractured monolith. This approach enables the model to represent a range of breakup behaviors and reproduce detailed energy deposition features such as multiple flares due to successive burst events, high-altitude regolith blow-off, or initial disruption of rubble piles followed by more energetic breakup of the constituent boulders. These capabilities provide a means to investigate sensitivities of ground damage to potential variations in asteroid structure.

Stellar Occultation Studies of the Solar System

NASA Technical Reports Server (NTRS)

Elliot, James L.

1998-01-01

Earth-based observations of stellar occultations provide extremely high spatial resolution for bodies in the outer solar system, about 10,000 times better than that of traditional imaging observations. Stellar occultation data can be used to establish the structure of atmospheres and rings of solar system bodies at high spatial resolution. Airborne occultation observations are particularly effective, since the controlled mobility of the observing platform allows the observer to fly within the optimum part of the occultation shadow for most events that are visible from Earth. Airborne observations are carried out above any clouds and are nearly free of scintillation noise from the Earth's atmosphere. KAO occultation observations resulted in the first detection of gravity waves in the Martian atmosphere, discovery of the Uranian rings, the first detection of Pluto's atmosphere, the first Earth-based investigations of Triton's atmosphere, and the discovery of narrow jets from Chiron's nucleus. The first SOFIA occultation opportunity will be an investigation of Pluto's atmospheric structure in November, 2002, and will resolve a problem that has lingered since the KAO discovery observation fourteen years earlier. We plan to continue our successful airborne occultation program with the greatly enhanced capability provided by SOFIA. We propose here to replace our KAO occultation photometer with one having twice the throughput, half the noise, a somewhat wider wavelength range, four times the field of view, and ten times the frame rate to optimize its performance and to capitalize on the larger collecting area offered by SOFIA. It will also allow for simultaneous visible and IR occultation observations, greatly enriching the results that we can obtain from occultations. We call this new imaging occultation photometer HOPI (High-speed Occultation Photometer and Imager). HOPI will provide a signal-to-noise ratio two to four times that of our present photometer for a given event, will permit useful observations of the more numerous events involving fainter stars, and will allow higher time resolution observations to be made. HOPI's characteristics also make it an ideal instrument for initial and ongoing evaluations of the SOFIA telescope's performance.

The ultraviolet spectrum of noncoronal late-type stars - The Gamma Crucis (M3.4 III) reference spectrum

NASA Technical Reports Server (NTRS)

Carpenter, Kenneth G.; Pesce, Joseph E.; Stencel, Robert E.; Brown, Alexander; Johansson, Sveneric

1988-01-01

A guide is presented to the UV spectrum of M-type giants and supergiants whose outer atmospheres contain warm chromospheres but not coronae. The M3 giant Gamma Crucis is taken as the archetype of the cooler, oxygen-rich, noncoronal stars. Line identifications and integrated line flux measurements of the chromospheric emission features seen in the 1200-3200 A range of IUE high-resolution spectra are presented. The major fluorescence processes operating in the outer atmosphere of Gamma Crucis, including eight previously unknown pumping processes and 21 new fluorescent line products, are summarized, and the enhancements of selected line strengths by 'line leakage' is discussed. A set of absorption features toward the longer wavelength end of this range is identified which can be used to characterize the radial velocity of the stellar photospheres. The applicability of the results to the spectra of noncoronal stars with different effective temperatures and gravities is discussed.

Noble Gas Inventory of Micrometeorites Collected at the Transantarctic Mountains (TAM) and Indications for Their Provenance

NASA Technical Reports Server (NTRS)

Ott, U.; Baecker, B.; Folco, L.; Cordier, C.

2016-01-01

A variety of processes have been considered possibly contributing the volatiles including noble gases to the atmospheres of the terrestrial planets (e.g., [1-3]). Special consideration has been given to the concept of accretion of volatile-rich materials by the forming planets. This might include infalling planetesimals and dust, and could include material from the outer asteroid belt, as well as cometary material from the outer solar system. Currently, the dominant source of extraterrestrial material accreted by the Earth is represented by micrometeorites (MMs) with sizes mostly in the 100-300 micron range [3, 4]). Their role has been assessed by [3], who conclude that accretion of early micrometeorites played a major role in the formation of the terrestrial atmosphere and oceans. We have therefore set out to investigate in more detail the inventory of noble gases in MMs. Here we summarize some of our results obtained on MMs collected in micrometeorite traps of the Transantarctic Mountains [5].

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.

Structural Loading on the QCM/SAW Instrument Aboard the ER-2 Used for Atmospheric Testing

NASA Technical Reports Server (NTRS)

Bainum, Peter M.; Jones, Phyllis D.; Irish, Sandra M.; Xing, Guang-Qian

1998-01-01

Several experiments have been proposed to capture and evaluate samples of the atmosphere where SST's travel. One means to achieve this is to utilize the quartz crystal microbalance (QCM) / surface acoustical wave (SAW) instrument installed aboard the ER-2, formerly the U-2 reconnaissance aircraft. The QCM is a cascade impactor designed to perform in-situ, real-time measurements of aerosols and chemical vapors at an altitude of 60,000-70,000 feet. The primary use of the ER-2 is by NASA for Earth resources to test new sensor systems before being placed aboard satellites. One of the main reasons the ER-2 is used for this flight experiment is its capability to fly approximately twelve miles above the sea level (can reach an altitude of 78,000 feet). Because the ER-2 operates at such a high altitude, it is of special interest to scientists interested in space exploration or supersonic aircraft. The purpose of some of the experiments is to extinct data from the atmosphere around the ER-2. For the current CSTEA flight experiment, the housing of the QCM is in a frame that connects to an outer pod that attaches to the fuselage of the ER-2. Due to the location of the QCM within the housing frame and the location of the pod on the ER-2, the pod and its contents are subject to structural loads. In addition to structural loads, structural vibrations are also of importance because the QCM output data is based on the determination of beat frequencies between a pair of oscillators (one coated, the second uncoated, according to the chemical reaction being monitored). A structural analysis of this system can indicate whether potential resonances may exist between the (higher) structural modal frequencies and the beat frequencies. In addition undesirable deformations may result due to maximum expected static or dynamic loads during typical flight conditions. If the deformations are excessive they may adversely affect the accuracy the instrumentation output.

Purification and Bicelle Crystallization for Structure Determination of the E. coli Outer Membrane Protein TamA.

PubMed

Gruss, Fabian; Hiller, Sebastian; Maier, Timm

2015-01-01

TamA is an Omp85 protein involved in autotransporter assembly in the outer membrane of Escherichia coli. It comprises a C-terminal 16-stranded transmembrane β-barrel as well as three periplasmic POTRA domains, and is a challenging target for structure determination. Here, we present a method for crystal structure determination of TamA, including recombinant expression in E. coli, detergent extraction, chromatographic purification, and bicelle crystallization in combination with seeding. As a result, crystals in space group P21212 are obtained, which diffract to 2.3 Å resolution. This protocol also serves as a template for structure determination of other outer membrane proteins, in particular of the Omp85 family.

Superficial Macromolecular Arrays on the Cell Wall of Spirillum putridiconchylium

PubMed Central

Beveridge, T. J.; Murray, R. G. E.

1974-01-01

Electron microscopy of the cell envelope of Spirillum putridiconchylium, using negatively stained, thin-sectioned, and replicated freeze-etched preparations, showed two superficial wall layers forming a complex macromolecular pattern on the external surface. The outer structured layer was a linear array of particles overlying an inner tetragonal array of larger subunits. They were associated in a very regular fashion, and the complex was bonded to the outer, pitted surface of the lipopolysaccharide tripartite layer of the cell wall. The relationship of the components of the two structured layers was resolved with the aid of optical diffraction, combined with image filtering and reconstruction and linear and rotary integration techniques. The outer structural layer consisted of spherical 1.5-nm units set in double lines determined by the size and arrangement of 6- by 3-nm inner structural layer subunits, which bore one outer structural layer unit on each outer corner. The total effect of this arrangement was a double-ridged linear structure that was evident in surface replicas and negatively stained fragments of the whole wall. The packing of these units was not square but skewed by 2° off the perpendicular so that the “unit array” described by optical diffraction and linear integration appeared to be a deformed tetragon. The verity of the model was checked by using a photographically reduced image to produce an optical diffraction pattern for comparison with that of the actual layers. The correspondence was nearly perfect. Images PMID:4137219

Characterization of polymer chain fractions of kiwifruit starch.

PubMed

Li, Dongxing; Zhu, Fan

2018-02-01

In this report, the amylose composition and molecular structure of starches from the core and outer pericarp of 3 golden kiwifruit varieties were characterised, using enzymatic and chromatographic techniques. Starches from the core tissues of kiwifruit tend to have higher amylose contents (by ∼3-5%) and longer unit chains of both amylopectins and their φ, β-limit dextrins (LDs) than those of the outer pericarp starches. The contents of short B-chains of the φ, β-LDs of amylopectins from the outer pericarp were higher (by ∼3%) than those of φ, β-LDs of the core amylopectins. Overall, the composition and structure of starches from the outer pericarp and core tissues of a golden kiwifruit were different. This study provides a structural basis to further investigate the starch degradation in kiwifruit, which may be of importance for the storage and eating quality of the fruit. Copyright © 2017 Elsevier Ltd. All rights reserved.

Space Infrared Telescope Facility (SIRTF) science instruments

NASA Technical Reports Server (NTRS)

Ramos, R.; Hing, S. M.; Leidich, C. A.; Fazio, G.; Houck, J. R.

1989-01-01

Concepts of scientific instruments designed to perform infrared astronomical tasks such as imaging, photometry, and spectroscopy are discussed as part of the Space Infrared Telescope Facility (SIRTF) project under definition study at NASA/Ames Research Center. The instruments are: the multiband imaging photometer, the infrared array camera, and the infrared spectograph. SIRTF, a cryogenically cooled infrared telescope in the 1-meter range and wavelengths as short as 2.5 microns carrying multiple instruments with high sensitivity and low background performance, provides the capability to carry out basic astronomical investigations such as deep search for very distant protogalaxies, quasi-stellar objects, and missing mass; infrared emission from galaxies; star formation and the interstellar medium; and the composition and structure of the atmospheres of the outer planets in the solar sytem.

The interpretation of optical light variations of Centaurus X-3

NASA Technical Reports Server (NTRS)

Mauder, H.

1976-01-01

The interpretation of optical light variations of X-ray binaries is discussed for the case of negligible reflection effect. The limiting cases of synchronous rotation of the visible star (Roche configuration) and of no rotation (pure tidal deformation) are considered. The theoretical results are compared with the available light curves of Cen X-3. X-ray data of the Copernicus satellite are used to get an impression of the atmospheric structure of the outer layers of the visible component. It is shown, that the X-ray eclipse duration is in good agreement with the mass ration derived from the optical variations. The X-ray eclipse duration is discussed with respect to the extended low states, and a possible correlation of the extended lows with the appearance of the optical light curves is considered.

Atmospheric NLTE models for the spectroscopic analysis of blue stars with winds. III. X-ray emission from wind-embedded shocks

NASA Astrophysics Data System (ADS)

Carneiro, L. P.; Puls, J.; Sundqvist, J. O.; Hoffmann, T. L.

2016-05-01

Context. Extreme ultraviolet (EUV) and X-ray radiation emitted from wind-embedded shocks in hot, massive stars can affect the ionization balance in their outer atmospheres and can be the mechanism responsible for producing highly ionized atomic species detected in stellar wind UV spectra. Aims: To allow for these processes in the context of spectral analysis, we have implemented the emission from wind-embedded shocks and related physics into our unified, NLTE model atmosphere/spectrum synthesis code FASTWIND. Methods: The shock structure and corresponding emission is calculated as a function of user-supplied parameters (volume filling factor, radial stratification of shock strength, and radial onset of emission). We account for a temperature and density stratification inside the postshock cooling zones, calculated for radiative and adiabatic cooling in the inner and outer wind, respectively. The high-energy absorption of the cool wind is considered by adding important K-shell opacities, and corresponding Auger ionization rates have been included in the NLTE network. To test our implementation and to check the resulting effects, we calculated a comprehensive model grid with a variety of X-ray emission parameters. Results: We tested and verified our implementation carefully against corresponding results from various alternative model atmosphere codes, and studied the effects from shock emission for important ions from He, C, N, O, Si, and P. Surprisingly, dielectronic recombination turned out to play an essential role for the ionization balance of O iv/O v (particularly in dwarfs with Teff~ 45 000 K). Finally, we investigated the frequency dependence and radial behavior of the mass absorption coefficient, κν(r), which is important in the context of X-ray line formation in massive star winds. Conclusions: In almost all of the cases considered, direct ionization is of major influence because of the enhanced EUV radiation field, and Auger ionization only affects N vi and O vi significantly. The approximation of a radially constant κν is justified for r ≳ 1.2 R∗ and λ ≲ 18 Å and also for many models at longer wavelengths. To estimate the actual value of this quantity, however, the He II opacities need to be calculated from detailed NLTE modeling, at least for wavelengths longer than 18 to 20 Å, and information on the individual CNO abundances has to be present.

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).

Structural Analysis of the QCM Aboard the ER-2

NASA Technical Reports Server (NTRS)

Jones, Phyllis D.; Bainum, Peter M.; Xing, Guangqian

1997-01-01

As a result of recent supersonic transport (SST) studies on the effect they may have on the atmosphere, several experiments have been proposed to capture and evaluate samples of the stratosphere where SST's travel. One means to achieve this is to utilize the quartz crystal microbalance (QCM) installed aboard the ER-2, formerly the U-2 reconnaissance aircraft. The QCM is a cascade impactor designed to perform in-situ, real-time measurements of aerosols and chemical vapors at an altitude of 60,000 - 70,000 feet. The ER-2 is primarily used by NASA for Earth resources to test new sensor systems before they are placed aboard satellites. One of the main reasons the ER-2 is used for this flight experiment is its capability to fly approximately twelve miles above sea level (can reach an altitude of 78,000 feet). Because the ER-2 operates at such a high altitude, it is of special interest to scientists interested in space exploration or supersonic aircraft. Some of the experiments are designed to extract data from the atmosphere around the ER-2. For the current flight experiment, the QCM is housed in a frame that is connected to an outer pod that is attached to the fuselage of the ER-2. Due to the location of the QCM within the housing frame and the location of the pod on the ER-2, the pod and its contents are subject to structural loads. In addition to structural loads, structural vibrations are also of importance because the QCM is a frequency induced instrument. Therefore, a structural analysis of the instrument within the frame is imperative to determine if resonance and/or undesirable deformations occur.

Sub-nm 3D observation of human hair melanin by high-voltage STEM.

PubMed

Imai, Takehito; Higuchi, Kimitaka; Yamamoto, Yuta; Arai, Shigeo; Nakano, Takashi; Tanaka, Nobuo

2016-04-01

The ultrastructure of melanin granules in human hair was studied using 1,000 kV high-voltage scanning transmission electron microscopy to successfully reconstruct three-dimensional images of the whole melanin granule. It was revealed that the melanin granule was composed of a membrane-like outer structure that included many spherical vesicles, and an inner matrix containing a sheet-like structure in the elongated direction of the melanin granule and a sheet-like arrays structure in the cross direction. The outer structure of the melanin granule was maintained even after exposure to hair-bleaching agents to decompose the melanin granule, suggesting that the outer structure was a highly robust structure and composition compared with the inner matrix . © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Dust inflated accretion disc as the origin of the broad line region in active galactic nuclei

NASA Astrophysics Data System (ADS)

Baskin, Alexei; Laor, Ari

2018-02-01

The broad line region (BLR) in active galactic nuclei (AGNs) is composed of dense gas (˜1011 cm-3) on sub-pc scale, which absorbs about 30 per cent of the ionizing continuum. The outer size of the BLR is likely set by dust sublimation, and its density by the incident radiation pressure compression (RPC). But, what is the origin of this gas, and what sets its covering factor (CF)? Czerny & Hryniewicz (2011) suggested that the BLR is a failed dusty wind from the outer accretion disc. We explore the expected dust properties, and the implied BLR structure. We find that graphite grains sublimate only at T ≃ 2000 K at the predicted density of ˜1011 cm-3, and therefore large graphite grains (≥0.3 μm) survive down to the observed size of the BLR, RBLR. The dust opacity in the accretion disc atmosphere is ˜50 times larger than previously assumed, and leads to an inflated torus-like structure, with a predicted peak height at RBLR. The illuminated surface of this torus-like structure is a natural place for the BLR. The BLR CF is mostly set by the gas metallicity, the radiative accretion efficiency, a dynamic configuration and ablation by the incident optical-UV continuum. This model predicts that the BLR should extend inwards of RBLR to the disc radius where the surface temperature is ≃2000 K, which occurs at Rin ≃ 0.18RBLR. The value of Rin can be tested by reverberation mapping of the higher ionization lines, predicted by RPC to peak well inside RBLR. The dust inflated disc scenario can also be tested based on the predicted response of RBLR and the CF to changes in the AGN luminosity and accretion rate.

Legal Implications of Nuclear Propulsion for Space Objects

NASA Astrophysics Data System (ADS)

Pop, V.

2002-01-01

This paper is intended to examine nuclear propulsion concepts such as "Project Orion", "Project Daedalus", NERVA, VASIMIR, from the legal point of view. The UN Principles Relevant to the Use of Nuclear Power Sources in Outer Space apply to nuclear power sources in outer space devoted to the generation of electric power on board space objects for non-propulsive purposes, and do not regulate the use of nuclear energy as a means of propulsion. However, nuclear propulsion by means of detonating atomic bombs (ORION) is, in principle, banned under the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space, and Under Water. The legality of use of nuclear propulsion will be analysed from different approaches - historical (i.e. the lawfulness of these projects at the time of their proposal, at the present time, and in the future - in the light of the mutability and evolution of international law), spatial (i.e. the legal regime governing peaceful nuclear explosions in different spatial zones - Earth atmosphere, Earth orbit, Solar System, and interstellar space), and technical (i.e, the legal regime applicable to different nuclear propulsion techniques, and to the various negative effects - e.g. damage to other space systems as an effect of the electromagnetic pulse, etc). The paper will analyse the positive law, and will also come with suggestions "de lege ferenda".

Laboratory studies of low temperature rate coefficients: The atmospheric chemistry of the outer planets

NASA Technical Reports Server (NTRS)

Leone, Stephen R.

1995-01-01

The objectives of the research are to measure low temperature laboratory rate coefficients for key reactions relevant to the atmospheres of Titan and Saturn. These reactions are, for example, C2H + H2, CH4, C2H2, and other hydrocarbons which need to be measured at low temperatures, down to approximately 150 K. The results of this work are provided to NASA specialists who study modeling of the hydrocarbon chemistry of the outer planets. The apparatus for this work consists of a pulsed laser photolysis system and a tunable F-center probe laser to monitor the disappearance of C2H. A low temperature cell with a cryogenic circulating fluid in the outer jacket provides the gas handling system for this work. These elements have been described in detail in previous reports. Several new results are completed and the publications are just being prepared. The reaction of C2H with C2H2 has been measured with an improved apparatus down to 154 K. An Arrhenius plot indicates a clear increase in the rate coefficient at the lowest temperatures, most likely because of the long-lived (C4H3) intermediate. The capability to achieve the lowest temperatures in this work was made possible by construction of a new cell and addition of a multipass arrangement for the probe laser, as well as improvements to the laser system.

Harvesting a Sea of Data

ERIC Educational Resources Information Center

Busey, Amy; Krumhansl, Ruth; Mueller-Northcott, Julianne; Louie, Josephine; Kochevar, Randy; Krumhansl, Kira; Zetterlind, Virgil

2015-01-01

Scientific research is undergoing a "big data" revolution, as probes deployed in oceans, the atmosphere, and outer space provide near real-time data streams. As more and more data sets such as Ocean Tracks become available online, opportunities to engage students in the "Next Generation Science Standards" (NGSS Lead States…

Science with the solar optical telescope

NASA Technical Reports Server (NTRS)

Jordan, S. D.; Hogan, G. D.

1984-01-01

The Solar Optical Telescope (SOT) is designed to provide the solar physics community with the data necessary for solving several fundamental problems in the energetics and dynamics of the solar atmosphere. Among these problems are questions on the origin and evolution of the sun's magnetic field, heating of the outer solar atmosphere, and sources of the solar wind in the lower lying regions of the outer atmosphere. The SOT will be built under the management of NASA's Goddard Space Flight Center, with science instruments provided by teams led by Principal Investigators. The telescope will be built by the Perkin-Elmer Corporation, and the science instruments selected for the first flight will be provided by the Lockheed Palo Alto Research Laboratory (LPARL) and the California Institute of Technology, with actual construction of a combined science instrument taking place at the LPARL. The SOT has a 1.3-meter-diameter primary mirror that will be capable of achieving diffraction-limited viewing in the visible of 0.1 arc-second. This dimension is less than a hydrodynamic scale-height or a mean-free-path of a continuum photon in the solar atmosphere. Image stability will be achieved by a control system in the telescope, which moves both the primary and tertiary mirrors in tandem, and will be further enhanced by a correlation tracker in the combined science instrument. The SOT Facility is currently scheduled for its first flight on Spacelab at the beginning of the 1990's.

CHARACTERIZING THE ATMOSPHERES OF THE HR8799 PLANETS WITH HST/WFC3

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

Rajan, Abhijith; Patience, Jennifer; Barman, Travis

We present results from a Hubble Space Telescope (HST) program characterizing the atmospheres of the outer two planets in the HR8799 system. The images were taken over 15 orbits in three near-infrared (near-IR) medium-band filters—F098M, F127M, and F139M—using the Wide Field Camera 3. One of the three filters is sensitive to a water absorption band inaccessible from ground-based observations, providing a unique probe of the thermal emission from the atmospheres of these young giant planets. The observations were taken at 30 different spacecraft rolls to enable angular differential imaging (ADI), and the full data set was analyzed with the Karhunen–Loévemore » Image Projection routine, an advanced image processing algorithm adapted to work with HST data. To achieve the required high contrast at subarcsecond resolution, we utilized the pointing accuracy of HST in combination with an improved pipeline designed to combine the dithered ADI data with an algorithm designed to both improve the image resolution and accurately measure the photometry. The results include F127M (J) detections of the outer planets, HR8799b and c, and the first detection of HR8799b in the water-band (F139M) filter. The F127M photometry for HR8799c agrees well with fitted atmospheric models, resolving the longstanding difficulty in consistently modeling the near-IR flux of the planet.« less

Material with core-shell structure

DOEpatents

Luhrs, Claudia [Rio Rancho, NM; Richard, Monique N [Ann Arbor, MI; Dehne, Aaron [Maumee, OH; Phillips, Jonathan [Rio Rancho, NM; Stamm, Kimber L [Ann Arbor, MI; Fanson, Paul T [Brighton, MI

2011-11-15

Disclosed is a material having a composite particle, the composite particle including an outer shell and a core. The core is made from a lithium alloying material and the outer shell has an inner volume that is greater in size than the core of the lithium alloying material. In some instances, the outer mean diameter of the outer shell is less than 500 nanometers and the core occupies between 5 and 99% of the inner volume. In addition, the outer shell can have an average wall thickness of less than 100 nanometers.

Structure and Dynamics of Coronal Plasmas

NASA Technical Reports Server (NTRS)

Golub, Leon

1997-01-01

During the past year this grant has funded research in the interaction between magnetic fields and the hot plasma in the solar outer atmosphere. The following is a brief summary of the published papers, abstracts and talks which have been supported. The paper 'Coronal Structures Observed in X-rays and H-alpha Structures' was published in the Kofu Symposium proceedings. The study analyzes cool and hot behavior of two x-ray events, a small flare and a surge. We find that a large H-alpha surge appears in x-rays as a very weak event, while a weak H-alpha feature corresponds to the brightest x-ray emission on the disk at the time of the observation. Calculations of the heating necessary to produce these signatures, and implications for the driving and heating mechanisms of flares vs. surges are presented. A copy of the paper is appended to this report. The paper 'Differential Magnetic Field Shear in an Active Region' has been published in The Astrophysical Journal. We have compared the 3D extrapolation of magnetic fields with the observed coronal structure in an active region. Based on the fit between observed coronal structure throughout the volume of the region and the calculated magnetic field configurations, we propose a differential magnetic field shear model for this active region. The decreasing field shear in the outer portions of the AR may indicate a continual relaxation of the magnetic field with time, corresponding to a net transport of helicity outward. The paper 'Difficulties in Observing Coronal Structure' has been accepted for publication in the journal Solar Physics. In this paper we discuss the evidence that the temperature and density structure of the corona are far more complicated than had previously been thought. The discussion is based on five studies carried out by our group on coronal plasma properties, showing that any one x-ray instrument does see all of the plasma present in the corona, that hot and cool material may appear to be co-spatial at a given location in the corona, and that simple magnetic field extrapolations provide only a poor fit to the observed structure. A copy of the paper is appended to this report.

Sputtering of ices in the outer solar system

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

Johnson, R.E.

1996-01-01

Exploration of the outer solar system has led to studies in a new area of physics: electronically induced sputtering of low-temperature, condensed-gas solids (ices). Many of the icy bodies in the outer solar system were found to be bombarded by relatively intense fluxes of ions and electrons, causing both changes in their optical reflectance and ejection (sputtering) of molecules from their surfaces. The small cohesive energies of the condensed-gas solids afford relatively large sputtering rates from the electronic excitations produced in the solid by fast ions and electrons. Such sputtering produces an ambient gas about an icy body, often themore » source of the local plasma. This colloquium outlines the physics of the sputtering of ices and its relevance to several outer-solar-system phenomena: the sputter-produced plasma trapped in Saturn{close_quote}s magnetosphere; the O{sub 2} atmosphere on Europa; and optical absorption features such as SO{sub 2} in the surface of Europa and O{sub 2} and, possibly, O{sub 3} in the surface of Ganymede. {copyright} {ital 1996 The American Physical Society.}« less

Ablative shielding for hypervelocity projectiles

NASA Technical Reports Server (NTRS)

Rucker, Michelle A. (Inventor)

1993-01-01

A hypervelocity projectile shield which includes a hollow semi-flexible housing fabricated from a plastic like, or otherwise transparent membrane which is filled with a fluid (gas or liquid) is presented. The housing has a inlet valve, similar to that on a tire or basketball, to introduce an ablating fluid into the housing. The housing is attached by a Velcro mount or double-sided adhesive tape to the outside surface of a structure to be protected. The housings are arrayed in a side-by-side relationship for complete coverage of the surface to be protected. In use, when a hypervelocity projectile penetrates the outer wall of a housing it is broken up and then the projectile is ablated as it travels through the fluid, much like a meteorite 'burns up' as it enters the earth's atmosphere, and the housing is deflated. The deflated housing can be easily spotted for replacement, even from a distance. Replacement is then accomplished by simply pulling a deflated housing off the structure and installing a new housing.

Concrete Infrastructure Corrosion

NASA Astrophysics Data System (ADS)

Waanders, F. B.; Vorster, S. W.

2003-06-01

It is well known that many reinforced concrete structures are at risk of deterioration due to chloride ion contamination of the concrete or atmospheric carbon dioxide dissolving in water to form carbonic acid, which reacts with the concrete and the reinforcing steel. The environment within the concrete will determine the corrosion product layers, which might, inter alia, contain the oxides and/or hydroxides of iron. Tensile forces resulting from volume changes during their formation lead to the cracking and delamination of the concrete. In the present investigation the handrail of an outside staircase suffered rebar corrosion during 30 year's service, leading to severe delamination damage to the concrete structure. The railings had been sealed into the concrete staircase using a polysulphide sealant, Thiokol®. The corrosion products were identified by means of Mössbauer and SEM analyses, which indicated that the corrosion product composition varied from the original steel surface to the outer layers, the former being mainly iron oxides and the latter iron oxyhydroxide.

Jovian Small Orbiter for Magnetospheric and Auroral Studies

NASA Astrophysics Data System (ADS)

Takashima, T.; Kasaba, Y.; Misawa, H.; Kawaguchi, J.

2005-12-01

Solar-Sail Project to have been examined by ISAS/JAXA as an engineering mission has a possibility of a small probe into the Jovian orbit. This paper summarizes the basic design of Jovian magnetospheric and auroral studies by this small chance. The large-scale Jovian mission has been a hope since the 1970s when the examinations of planetary exploration were started in Japan. In the one of plans, the largest planet in the solar system would be solved by two main objectives: (1) Structure of a gas planet: the internal & atmospheric structures of a gas planet which could not become a star (following the objectives of Planet-C and BepiColombo). (2) Jovian-type magnetosphere: the process of a pulsar-like magnetosphere with the strongest magnetospheric activities in the solar system (following the objectives of BepiColombo and SCOPE). The small polar-orbit orbiter in Solar-Sail Project aims to establish the feasibility of such future outer planet missions by ISAS/JAXA. It aims the former target in its limited resources.

Drug discovery strategies to outer membrane targets in Gram-negative pathogens.

PubMed

Brown, Dean G

2016-12-15

This review will cover selected recent examples of drug discovery strategies which target the outer membrane (OM) of Gram-negative bacteria either by disruption of outer membrane function or by inhibition of essential gene products necessary for outer membrane assembly. Significant advances in pathway elucidation, structural biology and molecular inhibitor designs have created new opportunities for drug discovery within this target-class space. Copyright © 2016 Elsevier Ltd. All rights reserved.

Outer satellite atmospheres: Their nature and planetary interactions. [atmospheric models for Amalthea, Ganymede, Callisto, and Titan are presented

NASA Technical Reports Server (NTRS)

Smyth, W. H.

1978-01-01

Results show that Amalthea is likely to form a tightly-bound partial toroidal-shaped hydrogen cloud about its planet, while Ganymede, Callisto and Titan may have rather large, complete and nearly symmetric toroidal-shaped clouds. The toroidal cloud for Amalthea compares favorably with spacecraft data of Pioneer 10 for a satellite escape flux of order 10 to the 11th power atoms/sq cm/sec. Model results for Ganymede, Callisto and Titan suggest that these extended hydrogen atmospheres are likely to be detected by the Voyager spacecrafts and that Titan's cloud might also be detected by the Pioneer 11 spacecraft. Ions created because of atoms lost through ionization processes from these four extended hydrogen atmospheres and from the sodium cloud of Io are discussed.

Under Jupiter's Cloud Tops

NASA Image and Video Library

2017-05-25

NASA's Juno spacecraft carries an instrument called the Microwave Radiometer, which examines Jupiter's atmosphere beneath the planet's cloud tops. This image shows the instrument's view of the outer part of Jupiter's atmosphere. Before Juno began using this instrument, scientists expected the atmosphere to be uniform at depths greater than 60 miles (100 kilometers). But with the Microwave Radiometer, scientists have discovered that the atmosphere has variations down to at least 220 miles (350 kilometers), as deep as the instrument can see. In the cut-out image to the right, orange signifies high ammonia abundance and blue signifies low ammonia abundance. Jupiter appears to have a band around its equator high in ammonia abundance, with a column shown in orange. This is contrary to scientists' expectations that ammonia would be uniformly mixed. https://photojournal.jpl.nasa.gov/catalog/PIA21642

Strategy for exploration of the outer planets: 1986-1996

NASA Technical Reports Server (NTRS)

1986-01-01

Over the past decade COMPLEX has published three strategy reports which, taken together, encompass the entire planetary system and recommend a coherent program of planetary exploration. The highest priority for outer planet exploration during the next decade is intensive study of Saturn (the planet, satellites, rings, and magnetosphere) as a system. The Committee additionally recommends that NASA engage in the following supporting activities: increased support of laboratory and theoretical studies; pursuit of earth-based and earth-orbital observations; commitment to continued operation of productive spacecraft; implementation of the instrument development plan as appropriate for the outer solar system; studies of deep atmospheric probes; development of penetrators or other hard landers; development of radiation-hardened spacecraft; and development of low-thrust propulsion systems. Longer-term objectives include exploration and intensive study of: the Uranus and Neptune systems; planetology of the Galilean satellites and Titan; and the inner Jovian system.

46 CFR 154.170 - Outer hull steel plating.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Outer hull steel plating. 154.170 Section 154.170... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Hull Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the...

Catching Cosmic Rays with a DSLR

ERIC Educational Resources Information Center

Sibbernsen, Kendra

2010-01-01

Cosmic rays are high-energy particles from outer space that continually strike the Earth's atmosphere and produce cascades of secondary particles, which reach the surface of the Earth, mainly in the form of muons. These particles can be detected with scintillator detectors, Geiger counters, cloud chambers, and also can be recorded with commonly…

50 CFR 216.212 - Effective dates.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Effective dates. 216.212 Section 216.212 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION... Removal Operations on the Outer Continental Shelf in the U.S. Gulf of Mexico § 216.212 Effective dates...

Chromospheric Lyman-alpha spectro-polarimeter (CLASP)

NASA Astrophysics Data System (ADS)

Kano, Ryouhei; Bando, Takamasa; Narukage, Noriyuki; Ishikawa, Ryoko; Tsuneta, Saku; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Shin-nosuke; Hara, Hirohisa; Shimizu, Toshifumi; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Sakao, Taro; Goto, Motoshi; Kato, Yoshiaki; Imada, Shinsuke; Kobayashi, Ken; Holloway, Todd; Winebarger, Amy; Cirtain, Jonathan; De Pontieu, Bart; Casini, Roberto; Trujillo Bueno, Javier; Štepán, Jiří; Manso Sainz, Rafael; Belluzzi, Luca; Asensio Ramos, Andres; Auchère, Frédéric; Carlsson, Mats

2012-09-01

One of the biggest challenges in heliophysics is to decipher the magnetic structure of the solar chromosphere. The importance of measuring the chromospheric magnetic field is due to both the key role the chromosphere plays in energizing and structuring the outer solar atmosphere and the inability of extrapolation of photospheric fields to adequately describe this key boundary region. Over the last few years, significant progress has been made in the spectral line formation of UV lines as well as the MHD modeling of the solar atmosphere. It is found that the Hanle effect in the Lyman-alpha line (121.567 nm) is a most promising diagnostic tool for weaker magnetic fields in the chromosphere and transition region. Based on this groundbreaking research, we propose the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) to NASA as a sounding rocket experiment, for making the first measurement of the linear polarization produced by scattering processes and the Hanle effect in the Lyman-alpha line (121.567 nm), and making the first exploration of the magnetic field in the upper chromosphere and transition region of the Sun. The CLASP instrument consists of a Cassegrain telescope, a rotating 1/2-wave plate, a dual-beam spectrograph assembly with a grating working as a beam splitter, and an identical pair of reflective polarization analyzers each equipped with a CCD camera. We propose to launch CLASP in December 2014.

System protection from atmospheric electricity for aerostats with conducting tethers

NASA Astrophysics Data System (ADS)

Wheeler, M. S.; Beach, G. R.; Jakubowski, P. R.; Fisher, F. A.

1988-04-01

Aerostat power tethers have demonstrated survival of lightning strikes, but they usually have to be reterminated or replaced afterward. Two requirements are given for the prevention of lightning damage to the tether to about 100 kA: installation of a metal-to-metal contact on the outer tether surface to ground the tether at the base flying sheave at typical flying positions; and installation of a shielding band within the outer tether jacket with a weight of about 0.05 lb/ft for a half-inch tether. This determination was made in part by high current tests and in part by electrical modeling.

Gas hydrate potential of the mid Atlantic outer continental shelf

USGS Publications Warehouse

Shedd, William W.; Hutchinson, Deborah R.

2006-01-01

For the last two years, the Minerals Management Service (MMS) has been studying the resource potential of gas hydrates in federal offshore lands of the Outer Continental Shelf (OCS) off the Atlantic, Gulf of Mexico, Pacific, and Alaska in collaboration with the U.S. Geological Survey (USGS), the Department of Energy (DOE), the National Oceanic and Atmospheric Administration (NOAA), the Naval Research Lab (NRL) and academia. Utilizing its extensive seismic, well, and geochemical databases, the MMS will be reporting the in-place resource numbers within the next few months. Though the methodology of the study was not prospect oriented, discrete prospects have been recognized.

Mars Molniya Orbit Atmospheric Resource Mining

NASA Technical Reports Server (NTRS)

Mueller, Robert P.; Braun, Robert D.; Sibille, Laurent; Sforzo, Brandon; Gonyea, Keir; Ali, Hisham

2016-01-01

This NIAC (NASA Advanced Innovative Concepts) work will focus on Mars and will build on previous efforts at analyzing atmospheric mining at Earth and the outer solar system. Spacecraft systems concepts will be evaluated and traded, to assess feasibility. However the study will primarily examine the architecture and associated missions to explore the closure, constraints and critical parameters through sensitivity studies. The Mars atmosphere consists of 95.5 percent CO2 gas which can be converted to methane fuel (CH4) and Oxidizer (O2) for chemical rocket propulsion, if hydrogen is transported from electrolyzed water on the Mars surface or from Earth. By using a highly elliptical Mars Molniya style orbit, the CO2 atmosphere can be scooped, ram-compressed and stored while the spacecraft dips into the Mars atmosphere at periapsis. Successive orbits result in additional scooping of CO2 gas, which also serves to aerobrake the spacecraft, resulting in a decaying Molniya orbit.

Superconducting coil and method of stress management in a superconducting coil

DOEpatents

McIntyre, Peter M.; Shen, Weijun; Diaczenko, Nick; Gross, Dan A.

1999-01-01

A superconducting coil (12) having a plurality of superconducting layers (18) is provided. Each superconducting layer (18) may have at least one superconducting element (20) which produces an operational load. An outer support structure (24) may be disposed outwardly from the plurality of layers (18). A load transfer system (22) may be coupled between at least one of the superconducting elements (20) and the outer support structure (24). The load transfer system (22) may include a support matrix structure (30) operable to transfer the operational load from the superconducting element (20) directly to the outer support structure (24). A shear release layer (40) may be disposed, in part, between the superconducting element (20) and the support matrix structure (30) for relieving a shear stress between the superconducting element (20) and the support matrix structure (30). A compliant layer (42) may also be disposed, in part, between the superconducting element (20) and the support matrix structure (30) for relieving a compressive stress on the superconducting element (20).

From Hot to Hottest

NASA Image and Video Library

2017-10-31

This sequence of images shows the sun from its surface to its upper atmosphere all taken at about the same time (Oct. 27, 2017). The first shows the surface of the sun in filtered white light; the other seven images were taken in different wavelengths of extreme ultraviolet light. Note that each wavelength reveals somewhat different features. They are shown in order of temperature from the first one at 6,000 degree C. surface out to about 10 million degrees C. in the upper atmosphere. Yes, the sun's outer atmosphere is much, much hotter than the surface. Scientists are getting closer to solving the processes that generate this phenomenon. https://photojournal.jpl.nasa.gov/catalog/PIA22055

Multifocal microlens for bionic compound eye

NASA Astrophysics Data System (ADS)

Cao, Axiu; Wang, Jiazhou; Pang, Hui; Zhang, Man; Shi, Lifang; Deng, Qiling; Hu, Song

2017-10-01

Bionic compound eye optical element composed of multi-dimensional sub-eye microlenses plays an important role in miniaturizing the volume and weight of an imaging system. In this manuscript, we present a novel structure of the bionic compound eye with multiple focal lengths. By the division of the microlens into two concentric radial zones including the inner zone and the outer zone with independent radius, the sub-eye which is a multi-level micro-scale structure can be formed with multiple focal lengths. The imaging capability of the structure has been simulated. The results show that the optical information in different depths can be acquired by the structure. Meanwhile, the parameters including aperture and radius of the two zones, which have an influence on the imaging quality have been analyzed and discussed. With the increasing of the ratio of inner and outer aperture, the imaging quality of the inner zone is becoming better, and instead the outer zone will become worse. In addition, through controlling the radius of the inner and outer zone independently, the design of sub-eye with different focal lengths can be realized. With the difference between the radius of the inner and outer zone becoming larger, the imaging resolution of the sub-eye will decrease. Therefore, the optimization of the multifocal structure should be carried out according to the actual imaging quality demands. Meanwhile, this study can provide references for the further applications of multifocal microlens in bionic compound eye.

Effect of Steel Framing for Securing Drywall Panels on Thermal and Humidity Parameters of the Outer Walls

NASA Astrophysics Data System (ADS)

Major, Maciej; Kosiń, Mariusz

2017-12-01

The paper analyses the effect of steel framing used to secure drywall panels on thermal and humidity properties of outer walls. In the practice of building a light structure, the most popular components are steel and wood studs. They are used to obtain framing for building a wall (an outer wall in this study). Analysis presented in this study concerned the corner of the outer wall build using the technology of light steel framing. Computer simulation was used to perform thermal and humidity analysis for the joint of the outer wall.

Solar Observations with ALMA

NASA Astrophysics Data System (ADS)

Wedemeyer, Sven

2018-04-01

The continuum intensity at millimeter wavelengths can serve as an essentially linear thermometer of the plasma in a thin layer in the atmosphere of the Sun, whereas the polarisation of the received radiation is a measure for the longitudinal magnetic field component in the same layer. The enormous leap in terms of spatial resolution with the Atacama Large Millimeter/submillimeter Array (ALMA) now makes it possible to observe the intricate fine-structure of the solar atmosphere at sufficiently high spatial, temporal, and spectral resolution, thus enabling studies of a wide range of scientific topics in solar physics that had been inaccessible at millimeter wavelengths before. The radiation observed by ALMA originates mostly from the chromosphere - a complex and dynamic layer between the photosphere and corona, which plays a crucial role in the transport of energy and matter and, ultimately, the heating of the outer solar atmosphere. ALMA observations of the solar chromosphere, which are offered as a regular capability since 2016, therefore have the potential to make important contributions towards the solution of fundamental questions in solar physics with implications for our understanding of stars in general. In this presentation, I will give a short description of ALMA's solar observing mode, it challenges and opportunities, and selected science cases in combination with numerical simulations and coordinated observations at other wavelengths. ALMA's scientific potential for studying the dynamic small-scale pattern of the solar chromosphere is illustrated with first results from Cycle 4.

Noncircular outer disks in unbarred S0 galaxies: NGC 502 and NGC 5485

NASA Astrophysics Data System (ADS)

Sil'chenko, O. K.

2016-03-01

Highly noncircular outer stellar disks have been detected in two SA0 (unbarred) galaxies by comparing the spectroscopic data on the rotation of stars and the photometric data on the shape and orientation of isophotes. In NGC 502, the oval distortion of the disk is manifested in the shape of the inner and outer elliptical rings occupying wide radial zones between the bulge and the disk and at the outer disk edge; such a structure can be a consequence of the so-called "dry minor merger," multiple cannibalization of gas-free satellites. In NGC 5485, the stellar kinematics is absolutely unrelated to the orientation of isophotes in the disk region, and for this galaxy the conclusion about its global triaxial structure is unavoidable.

Structural and functional changes associated with normal and abnormal fundus autofluorescence in patients with retinitis pigmentosa.

PubMed

Greenstein, Vivienne C; Duncker, Tobias; Holopigian, Karen; Carr, Ronald E; Greenberg, Jonathan P; Tsang, Stephen H; Hood, Donald C

2012-02-01

To analyze the structure and visual function of regions bordering the hyperautofluorescent ring/arcs in retinitis pigmentosa. Twenty-one retinitis pigmentosa patients (21 eyes) with rings/arcs and 21 normal individuals (21 eyes) were studied. Visual sensitivity in the central 10° was measured with microperimetry. Retinal structure was evaluated with spectral-domain optical coherence tomography. The distance from the fovea to disruption/loss of the inner outer segment (IS/OS) junction and thicknesses of the total receptor plus retinal pigment epithelial complex and outer segment plus retinal pigment epithelial complex layers were measured. Results were compared with measurements of the distance from the fovea to the inner and outer borders of the ring/arc seen on fundus autofluorescence. Disruption/loss of the inner outer segment junction occurred closer to the inner border of the ring/arc and it was closer to the fovea in eight eyes. For 19 eyes, outer segment plus and receptor plus RPE complex thicknesses were significantly decreased at locations closer to the fovea than the appearance of the inner border of hyperautofluorescence. Mean visual sensitivity was decreased inside, across, and outside the ring/arc by 3.5 ± 3.8, 8.9 ± 4.8, and 17.0 ± 2.4 dB, respectively. Structural and functional changes can occur inside the hyperfluorescent ring/arc in retinitis pigmentosa.

The Properties of Outer Retinal Band Three Investigated With Adaptive-Optics Optical Coherence Tomography.

PubMed

Jonnal, Ravi S; Gorczynska, Iwona; Migacz, Justin V; Azimipour, Mehdi; Zawadzki, Robert J; Werner, John S

2017-09-01

Optical coherence tomography's (OCT) third outer retinal band has been attributed to the zone of interdigitation between RPE cells and cone outer segments. The purpose of this paper is to investigate the structure of this band with adaptive optics (AO)-OCT. Using AO-OCT, images were obtained from two subjects. Axial structure was characterized by measuring band 3 thickness and separation between bands 2 and 3 in segmented cones. Lateral structure was characterized by correlation of band 3 with band 2 and comparison of their power spectra. Band thickness and separation were also measured in a clinical OCT image of one subject. Band 3 thickness ranged from 4.3 to 6.4 μm. Band 2 correlations ranged between 0.35 and 0.41 and power spectra of both bands confirmed peak frequencies that agree with histologic density measurements. In clinical images, band 3 thickness was between 14 and 19 μm. Measurements of AO-OCT of interband distance were lower than our corresponding clinical OCT measurements. Band 3 originates from a structure with axial extent similar to a single surface. Correlation with band 2 suggests an origin within the cone photoreceptor. These two observations indicate that band 3 corresponds predominantly to cone outer segment tips (COST). Conventional OCT may overestimate both the thickness of band 3 and outer segment length.

The Properties of Outer Retinal Band Three Investigated With Adaptive-Optics Optical Coherence Tomography

PubMed Central

Jonnal, Ravi S.; Gorczynska, Iwona; Migacz, Justin V.; Azimipour, Mehdi; Zawadzki, Robert J.; Werner, John S.

2017-01-01

Purpose Optical coherence tomography's (OCT) third outer retinal band has been attributed to the zone of interdigitation between RPE cells and cone outer segments. The purpose of this paper is to investigate the structure of this band with adaptive optics (AO)-OCT. Methods Using AO-OCT, images were obtained from two subjects. Axial structure was characterized by measuring band 3 thickness and separation between bands 2 and 3 in segmented cones. Lateral structure was characterized by correlation of band 3 with band 2 and comparison of their power spectra. Band thickness and separation were also measured in a clinical OCT image of one subject. Results Band 3 thickness ranged from 4.3 to 6.4 μm. Band 2 correlations ranged between 0.35 and 0.41 and power spectra of both bands confirmed peak frequencies that agree with histologic density measurements. In clinical images, band 3 thickness was between 14 and 19 μm. Measurements of AO-OCT of interband distance were lower than our corresponding clinical OCT measurements. Conclusions Band 3 originates from a structure with axial extent similar to a single surface. Correlation with band 2 suggests an origin within the cone photoreceptor. These two observations indicate that band 3 corresponds predominantly to cone outer segment tips (COST). Conventional OCT may overestimate both the thickness of band 3 and outer segment length. PMID:28877320

Secretins revealed: structural insights into the giant gated outer membrane portals of bacteria.

PubMed

Majewski, Dorothy D; Worrall, Liam J; Strynadka, Natalie Cj

2018-03-23

The acquisition and evolution of customized and often highly complex secretion systems allows Gram-negative bacteria to efficiently passage large macromolecules across both inner and outer membranes and, in some cases, that of the infected host. Essential to the virulence and ultimate survival of the many pathogenic species that encode them, secretion systems export a wide variety of effector proteins and DNA as well as the downstream extracellular filaments of the secretion apparatus themselves. Although these customized secretion systems differ in their cytosolic and inner membrane components, several commonly rely on the secretin family of giant pores to allow these large substrates to traverse the outer membrane. Recently, several near-atomic resolution cryo-EM secretin structures have unveiled the first insights into the unique structural motifs required for outer membrane localization, assembly, hallmark ultrastable nature, spontaneous membrane insertion, and mechanism of action-including the requisite central gating needed to prevent deleterious passage of periplasmic contents to the extracellular space. Copyright © 2018. Published by Elsevier Ltd.

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.

Heated-Atmosphere Airship for the Titan Environment: Thermal Analysis

NASA Technical Reports Server (NTRS)

Heller, R. S.; Landis, G. A.; Hepp, A. F.; Colozza, A. J.

2012-01-01

Future exploration of Saturn's moon Titan can be carried out by airships. Several lighter-than-atmosphere gas airships and passive drifting heated-atmosphere balloon designs have been studied, but a heated-atmosphere airship could combine the best characteristics of both. This work analyses the thermal design of such a heated-atmosphere vehicle, and compares the result with a lighter-than-atmosphere (hydrogen) airship design. A design tool was created to enable iteration through different design parameters of a heated-atmosphere airship (diameter, number of layers, and insulating gas pocket thicknesses) and evaluate the feasibility of the resulting airship. A baseline heated-atmosphere airship was designed to have a diameter of 6 m (outer diameter of 6.2 m), three-layers of material, and an insulating gas pocket thickness of 0.05 m between each layer. The heated-atmosphere airship has a mass of 161.9 kg. A similar mission making use of a hydrogen-filled airship would require a diameter of 4.3 m and a mass of about 200 kg. For a long-duration mission, the heated-atmosphere airship appears better suited. However, for a mission lifetime under 180 days, the less complex hydrogen airship would likely be a better option.

Air gap winding method and support structure for a super conducting generator and method for forming the same

DOEpatents

Hopeck, James Frederick

2003-11-25

A method of forming a winding support structure for use with a superconducting rotor wherein the method comprises providing an inner support ring, arranging an outer support ring around the inner support ring, coupling first and second support blocks to the outer support ring and coupling a lamination to the first and second support blocks. A slot is defined between the support blocks and between the outer support ring and the lamination to receive a portion of a winding. An RTV fills any clearance space in the slot.

Regeneratively Cooled Porous Media Jacket

NASA Technical Reports Server (NTRS)

Mungas, Greg (Inventor); Fisher, David J. (Inventor); London, Adam Pollok (Inventor); Fryer, Jack Merrill (Inventor)

2013-01-01

The fluid and heat transfer theory for regenerative cooling of a rocket combustion chamber with a porous media coolant jacket is presented. This model is used to design a regeneratively cooled rocket or other high temperature engine cooling jacket. Cooling jackets comprising impermeable inner and outer walls, and porous media channels are disclosed. Also disclosed are porous media coolant jackets with additional structures designed to transfer heat directly from the inner wall to the outer wall, and structures designed to direct movement of the coolant fluid from the inner wall to the outer wall. Methods of making such jackets are also disclosed.

Distance Measurement on an Endogenous Membrane Transporter in E. coli Cells and Native Membranes Using EPR Spectroscopy.

PubMed

Joseph, Benesh; Sikora, Arthur; Bordignon, Enrica; Jeschke, Gunnar; Cafiso, David S; Prisner, Thomas F

2015-05-18

Membrane proteins may be influenced by the environment, and they may be unstable in detergents or fail to crystallize. As a result, approaches to characterize structures in a native environment are highly desirable. Here, we report a novel general strategy for precise distance measurements on outer membrane proteins in whole Escherichia coli cells and isolated outer membranes. The cobalamin transporter BtuB was overexpressed and spin-labeled in whole cells and outer membranes and interspin distances were measured to a spin-labeled cobalamin using pulse EPR spectroscopy. A comparative analysis of the data reveals a similar interspin distance between whole cells, outer membranes, and synthetic vesicles. This approach provides an elegant way to study conformational changes or protein-protein/ligand interactions at surface-exposed sites of membrane protein complexes in whole cells and native membranes, and provides a method to validate outer membrane protein structures in their native environment. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Space weather effects measured in atmospheric radiation on aircraft

NASA Astrophysics Data System (ADS)

Tobiska, W. K.; Bouwer, D.; Bailey, J. J.; Didkovsky, L. V.; Judge, K.; Wieman, S. R.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R. W.; Bell, L. D.; Mertens, C. J.; Xu, X.; Wiltberger, M. J.; Wiley, S.; Teets, E.; Shea, M. A.; Smart, D. F.; Jones, J. B. L.; Crowley, G.; Azeem, S. I.; Halford, A. J.

2016-12-01

Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Since 2013 Space Environment Technologies (SET) has been conducting observations of the atmospheric radiation environment at aviation altitudes using a small fleet of six instruments. The objective of this work is to improve radiation risk management in air traffic operations. Under the auspices of the Automated Radiation Measurements for Aerospace Safety (ARMAS) and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) projects our team is making dose rate measurements on multiple aircraft flying global routes. Over 174 ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the radiation environment resulting from Galactic Cosmic Rays (GCRs), Solar Energetic Protons (SEPs), and outer radiation belt energetic electrons. The real-time radiation exposure is measured as an absorbed dose rate in silicon and then computed as an ambient dose equivalent rate for reporting dose relevant to radiative-sensitive organs and tissue in units of microsieverts per hour. ARMAS total ionizing absorbed dose is captured on the aircraft, downlinked in real-time, processed on the ground into ambient dose equivalent rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users. Dose rates from flight altitudes up to 56,700 ft. are shown for flights across the planet under a variety of space weather conditions. We discuss several space weather effects on the atmospheric radiation environment, including the levels of GCR background radiation, small SEP events, and possible EMIC wave driven energetic electrons from the outer radiation belt creating "radiation" clouds in the troposphere.

Hybrid Composite Cryogenic Tank Structure

NASA Technical Reports Server (NTRS)

DeLay, Thomas

2011-01-01

A hybrid lightweight composite tank has been created using specially designed materials and manufacturing processes. The tank is produced by using a hybrid structure consisting of at least two reinforced composite material systems. The inner composite layer comprises a distinct fiber and resin matrix suitable for cryogenic use that is a braided-sleeve (and/or a filamentwound layer) aramid fiber preform that is placed on a removable mandrel (outfitted with metallic end fittings) and is infused (vacuum-assisted resin transfer molded) with a polyurethane resin matrix with a high ductility at low temperatures. This inner layer is allowed to cure and is encapsulated with a filamentwound outer composite layer of a distinct fiber resin system. Both inner and outer layer are in intimate contact, and can also be cured at the same time. The outer layer is a material that performs well for low temperature pressure vessels, and it can rely on the inner layer to act as a liner to contain the fluids. The outer layer can be a variety of materials, but the best embodiment may be the use of a continuous tow of carbon fiber (T-1000 carbon, or others), or other high-strength fibers combined with a high ductility epoxy resin matrix, or a polyurethane matrix, which performs well at low temperatures. After curing, the mandrel can be removed from the outer layer. While the hybrid structure is not limited to two particular materials, a preferred version of the tank has been demonstrated on an actual test tank article cycled at high pressures with liquid nitrogen and liquid hydrogen, and the best version is an inner layer of PBO (poly-pphenylenebenzobisoxazole) fibers with a polyurethane matrix and an outer layer of T-1000 carbon with a high elongation epoxy matrix suitable for cryogenic temperatures. A polyurethane matrix has also been used for the outer layer. The construction method is ideal because the fiber and resin of the inner layer has a high strain to failure at cryogenic temperatures, and will not crack or produce leaks. The outer layer serves as more of a high-performance structural unit for the inner layer, and can handle external environments.

Characterizing the propagation path in moderate to strong optical turbulence.

PubMed

Vetelino, Frida Strömqvist; Clare, Bradley; Corbett, Kerry; Young, Cynthia; Grant, Kenneth; Andrews, Larry

2006-05-20

In February 2005 a joint atmospheric propagation experiment was conducted between the Australian Defence Science and Technology Organisation and the University of Central Florida. A Gaussian beam was propagated along a horizontal 1500 m path near the ground. Scintillation was measured simultaneously at three receivers of diameters 1, 5, and 13 mm. Scintillation theory combined with a numerical scheme was used to infer the structure constant C2n, the inner scale l0, and the outer scale L0 from the optical measurements. At the same time, C2n measurements were taken by a commercial scintillometer, set up parallel to the optical path. The C2n values from the inferred scheme and the commercial scintillometer predict the same behavior, but the inferred scheme consistently gives slightly smaller C2n values.

Galileo's First Images of Jupiter and the Galilean Satellites

PubMed

Belton, M J S; Head, J W; Ingersoll, A P; Greeley, R; McEwen, A S; Klaasen, K P; Senske, D; Pappalardo, R; Collins, G; Vasavada, A R; Sullivan, R; Simonelli, D; Geissler, P; Carr, M H; Davies, M E; Veverka, J; Gierasch, P J; Banfield, D; Bell, M; Chapman, C R; Anger, C; Greenberg, R; Neukum, G; Pilcher, C B; Beebe, R F; Burns, J A; Fanale, F; Ip, W; Johnson, T V; Morrison, D; Moore, J; Orton, G S; Thomas, P; West, R A

1996-10-18

The first images of Jupiter, Io, Europa, and Ganymede from the Galileo spacecraft reveal new information about Jupiter's Great Red Spot (GRS) and the surfaces of the Galilean satellites. Features similar to clusters of thunderstorms were found in the GRS. Nearby wave structures suggest that the GRS may be a shallow atmospheric feature. Changes in surface color and plume distribution indicate differences in resurfacing processes near hot spots on Io. Patchy emissions were seen while Io was in eclipse by Jupiter. The outer margins of prominent linear markings (triple bands) on Europa are diffuse, suggesting that material has been vented from fractures. Numerous small circular craters indicate localized areas of relatively old surface. Pervasive brittle deformation of an ice layer appears to have formed grooves on Ganymede. Dark terrain unexpectedly shows distinctive albedo variations to the limit of resolution.

Galileo's first images of Jupiter and the Galilean satellites

USGS Publications Warehouse

Belton, M.J.S.; Head, J. W.; Ingersoll, A.P.; Greeley, R.; McEwen, A.S.; Klaasen, K.P.; Senske, D.; Pappalardo, R.; Collins, G.; Vasavada, A.R.; Sullivan, R.; Simonelli, D.; Geissler, P.; Carr, M.H.; Davies, M.E.; Veverka, J.; Gierasch, P.J.; Banfield, D.; Bell, M.; Chapman, C.R.; Anger, C.; Greenberg, R.; Neukum, G.; Pilcher, C.B.; Beebe, R.F.; Burns, J.A.; Fanale, F.; Ip, W.; Johnson, T.V.; Morrison, D.; Moore, J.; Orton, G.S.; Thomas, P.; West, R.A.

1996-01-01

The first images of Jupiter, Io, Europa, and Ganymede from the Galileo spacecraft reveal new information about Jupiter's Great Red Spot (GRS) and the surfaces of the Galilean satellites. Features similar to clusters of thunderstorms were found in the GRS. Nearby wave structures suggest that the GRS may be a shallow atmospheric feature. Changes in surface color and plume distribution indicate differences in resurfacing processes near hot spots on lo. Patchy emissions were seen while Io was in eclipse by Jupiter. The outer margins of prominent linear markings (triple bands) on Europa are diffuse, suggesting that material has been vented from fractures. Numerous small circular craters indicate localized areas of relatively old surface. Pervasive brittle deformation of an ice layer appears to have formed grooves on Ganymede. Dark terrain unexpectedly shows distinctive albedo variations to the limit of resolution.

Outer satellite atmospheres: Their extended nature and planetary interactions. [sodium cloud of Io, hydrogen torus of Titan, and comet atmospheres

NASA Technical Reports Server (NTRS)

Smyth, W. H.

1980-01-01

Highly developed numerical models are applied to interpret extended-atmosphere data for the sodium cloud of Io and the hydrogen torus of Titan. Solar radiation pressure was identified and verified by model calculations as the mechanism to explain two different east-west asymmetries observed in the sodium cloud. Analysis of sodium line profile data, suggesting that a Jupiter magnetospheric wind may be responsible for high speed sodium atoms emitted from Io, and preliminary modeling of the interaction of the Io plasma torus and Io's sodium cloud are also reported. Models presented for Titan's hydrogen torus are consistent both with the recent Pioneer 11 measurements and earlier Earth-orbiting observations by the Copernicus satellite. Progress is reported on developing models for extended gas and dust atmospheres of comets.

Equivalent refractive-index structure constant of non-Kolmogorov turbulence.

PubMed

Li, Yujie; Zhu, Wenyue; Wu, Xiaoqing; Rao, Ruizhong

2015-09-07

The relationship between the non-Kolmogorov refractive-index structure constant and the Kolmogorov refractive-index structure constant is derived by using the refractive-index structure function and the variance of refractive-index fluctuations. It shows that the non-Kolmogorov structure constant is proportional to the Kolmogorov structure constant and the scaling factor depends on the outer scale and the spectral power law. For a fixed Kolmogorov structure constant, the non-Kolmogorov structure constant increases with a increasing outer scale for the power law less than 11/3, the trend is opposite for the power law greater than 11/3. This equivalent relation provides a way of obtaining the non-Kolmogorov structure constant by using the Kolmogorov structure constant.

Energy structure of MHD flow coupling with outer resistance circuit

NASA Astrophysics Data System (ADS)

Huang, Z. Y.; Liu, Y. J.; Chen, Y. Q.; Peng, Z. L.

2015-08-01

Energy structure of MHD flow coupling with outer resistance circuit is studied to illuminate qualitatively and quantitatively the energy relation of this basic MHD flow system with energy input and output. Energy structure are analytically derived based on the Navier-Stocks equations for two-dimensional fully-developed flow and generalized Ohm's Law. The influences of applied magnetic field, Hall parameter and conductivity on energy structure are discussed based on the analytical results. Associated energies in MHD flow are deduced and validated by energy conservation. These results reveal that energy structure consists of two sub structures: electrical energy structure and internal energy structure. Energy structure and its sub structures provide an integrated theoretical energy path of the MHD system. Applied magnetic field and conductivity decrease the input energy, dissipation by fluid viscosity and internal energy but increase the ratio of electrical energy to input energy, while Hall parameter has the opposite effects. These are caused by their different effects on Bulk velocity, velocity profiles, voltage and current in outer circuit. Understanding energy structure helps MHD application designers to actively adjust the allocation of different parts of energy so that it is more reasonable and desirable.

Aerospace Environment. Aerospace Education I.

ERIC Educational Resources Information Center

Savler, D. S.; Smith, J. C.

This book is one in the series on Aerospace Education I. It briefly reviews current knowledge of the universe, the earth and its life-supporting atmosphere, and the arrangement of celestial bodies in outer space and their physical characteristics. Chapter 1 includes a brief survey of the aerospace environment. Chapters 2 and 3 examine the…

NASA Facts: an Educational Publication of the National Aeronautics and Space Administration. the Voyager Mission. [Jupiter probes

NASA Technical Reports Server (NTRS)

1979-01-01

The evolution of Jupiter, as well as its rotation, atmosphere and magnetosphere are described in this third in a series of publications on the exploration of the outer planets by the Voyager spacecraft. Activities for student participation are included with a selected reading list.

Thermodynamics of clathrate hydrate at low and high pressures with application to the outer solar system

NASA Technical Reports Server (NTRS)

Lunine, J. I.; Stevenson, D. J.

1985-01-01

The thermodynamic stability of clathrate hydrate is calculated to predict the formation conditions corresponding to a range of solar system parameters. The calculations were performed using the statistical mechanical theory developed by van der Waals and Platteeuw (1959) and existing experimental data concerning clathrate hydrate and its components. Dissociation pressures and partition functions (Langmuir constants) are predicted at low pressure for CO clathrate (hydrate) using the properties of chemicals similar to CO. It is argued that nonsolar but well constrained noble gas abundances may be measurable by the Galileo spacecraft in the Jovian atmosphere if the observed carbon enhancement is due to bombardment of the atmosphere by clathrate-bearing planetesimals sometime after planetary formation. The noble gas abundances of the Jovian satellite Titan are predicted, assuming that most of the methane in Titan is accreted as clathrate. It is suggested that under thermodynamically appropriate conditions, complete clathration of water ice could have occurred in high-pressure nebulas around giant planets, but probably not in the outer solar nebula. The stability of clathrate in other pressure ranges is also discussed.

Water in stars: expected and unexpected

NASA Astrophysics Data System (ADS)

Tsuji, T.; Aoki, W.; Ohnaka, K.

1999-03-01

We have confirmed the presence of water in the early M giant α Cet (M1.5III) and supergiant KK Per (M2Iab) by the highest resolution grating mode of SWS, but this result is quite unexpected from present model atmospheres. In late M giant and supergiant stars, water observed originates partly in the photosphere as expected by the model atmospheres, but ISO SWS has revealed that the 2.7 mic\\ absorption bands appear to be somewhat stronger than predicted while 6.5 mic\\ bands weaker, indicating the contamination by an emission component. In the mid-infrared region extending to 45 mic, pure rotation lines of hho\\ appear as distinct emission on the high resolution SWS spectra of 30g Her (M7III) and S Per (M4-7Ia), along with the dust emission at 10, 13, 20 mic\\ and a new unidentified feature at 30 mic. Thus, together with the dust, water contributes to the thermal balance of the outer atmosphere already in the mid-infrared. The excitation temperature of hho\\ gas is estimated to be 500 - 1000 K. In view of this result for late M (super)giants, unexpected water observed in early M (super)giants should also be of non-photospheric in origin. Thus, ISO has finally established the presence of a new component of the outer atmosphere - a warm molecular envelope - in red giant and supergiant stars from early to late types. Such a rather warm molecular envelope will be a site of various activities such as chemical reactions, dust formation, mass-outflow etc.

A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters

NASA Astrophysics Data System (ADS)

Muñoz, Ricardo R.; Côté, Patrick; Santana, Felipe A.; Geha, Marla; Simon, Joshua D.; Oyarzún, Grecco A.; Stetson, Peter B.; Djorgovski, S. G.

2018-06-01

We present structural parameters from a wide-field homogeneous imaging survey of Milky Way satellites carried out with the MegaCam imagers on the 3.6 m Canada–France–Hawaii Telescope and 6.5 m Magellan-Clay telescope. Our survey targets an unbiased sample of “outer halo” satellites (i.e., substructures having galactocentric distances greater than 25 kpc) and includes classical dSph galaxies, ultra-faint dwarfs, and remote globular clusters. We combine deep, panoramic gr imaging for 44 satellites and archival gr imaging for 14 additional objects (primarily obtained with the DECam instrument as part of the Dark Energy Survey) to measure photometric and structural parameters for 58 outer halo satellites. This is the largest and most uniform analysis of Milky Way satellites undertaken to date and represents roughly three-quarters (58/81 ≃ 72%) of all known outer halo satellites. We use a maximum-likelihood method to fit four density laws to each object in our survey: exponential, Plummer, King, and Sérsic models. We systematically examine the isodensity contour maps and color–magnitude diagrams for each of our program objects, present a comparison with previous results, and tabulate our best-fit photometric and structural parameters, including ellipticities, position angles, effective radii, Sérsic indices, absolute magnitudes, and surface brightness measurements. We investigate the distribution of outer halo satellites in the size–magnitude diagram and show that the current sample of outer halo substructures spans a wide range in effective radius, luminosity, and surface brightness, with little evidence for a clean separation into star cluster and galaxy populations at the faintest luminosities and surface brightnesses.

Role of subunit assembly in autosomal dominant retinitis pigmentosa linked to mutations in peripherin 2.

PubMed

Molday, Robert S; Molday, Laurie L; Loewen, Christopher J R

2004-01-01

Peripherin 2 is a photoreceptor-specific membrane protein implicated in outer segment disk morphogenesis and linked to various retinopathies including autosomal dominant retinitis pigmentosa (ADRP). Peripherin 2 and ROM1 assemble as a mixture of core noncovalent homomeric and heteromeric tetramers that further link together through disulfide bonds to form higher order oligomers. These complexes are critical for disk rim formation and outer segment structure through interaction with the cGMP-gated channel and other photoreceptor proteins. We have examined the role of subunit assembly in peripherin 2 targeting to disks, outer segment structure, and photoreceptor degeneration by examining molecular and cellular properties of peripherin 2 mutants in COS-1 cells and transgenic Xenopus laevis rod photoreceptors. Wild-type (WT) and the ADRP-linked P216L mutant were transported and incorporated into newly formed outer segment disks of transgenic X. laevis. The P216L mutant, however, induced progressive outer segment instability and photoreceptor degeneration possibly through the introduction of a new N-linked oligosaccharide chain. In contrast, the C214S and L185P disease-linked, tetramerization-defective mutants, were retained in the inner segment, but did not affect outer segment structure or induce photoreceptor degeneration. Together, these results indicate that peripherin 2 mutations can cause ADRP either through a deficiency in WT peripherin 2 (C214S, 1.185P) or by a dominant negative effect on disk stability (P216L).

Assembly Platform For Use In Outer Space

NASA Technical Reports Server (NTRS)

Rao, Niranjan S.; Buddington, Patricia A.

1995-01-01

Report describes conceptual platform or framework for use in assembling other structures and spacecraft in outer space. Consists of three fixed structural beams comprising central beam and two cross beams. Robotic manipulators spaced apart on platform to provide telerobotic operation of platform by either space-station or ground crews. Platform and attached vehicles function synergistically to achieve maximum performance for intended purposes.

Dissecting a supernova impostor's circumstellar medium: MUSEing about the SHAPE of η Carinae's outer ejecta

NASA Astrophysics Data System (ADS)

Mehner, A.; Steffen, W.; Groh, J. H.; Vogt, F. P. A.; Baade, D.; Boffin, H. M. J.; Davidson, K.; de Wit, W. J.; Humphreys, R. M.; Martayan, C.; Oudmaijer, R. D.; Rivinius, T.; Selman, F.

2016-11-01

Aims: The role of episodic mass loss is one of the outstanding questions in massive star evolution. The structural inhomogeneities and kinematics of their nebulae are tracers of their mass-loss history. We conduct a three-dimensional morpho-kinematic analysis of the ejecta of η Car outside its famous Homunculus nebula. Methods: We carried out the first large-scale integral field unit observations of η Car in the optical, covering a field of view of 1'× 1' centered on the star. Observations with the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) reveal the detailed three-dimensional structure of η Car's outer ejecta. Morpho-kinematic modeling of these ejecta is conducted with the code SHAPE. Results: The largest coherent structure in η Car's outer ejecta can be described as a bent cylinder with roughly the same symmetry axis as the Homunculus nebula. This large outer shell is interacting with the surrounding medium, creating soft X-ray emission. Doppler velocities of up to 3000 km s-1 are observed. We establish the shape and extent of the ghost shell in front of the southern Homunculus lobe and confirm that the NN condensation can best be modeled as a bowshock in the orbital/equatorial plane. Conclusions: The SHAPE modeling of the MUSE observations provides a significant gain in the study of the three-dimensional structure of η Car's outer ejecta. Our SHAPE modeling indicates that the kinematics of the outer ejecta measured with MUSE can be described by a spatially coherent structure, and that this structure also correlates with the extended soft X-ray emission associated with the outer debris field. The ghost shell immediately outside the southern Homunculus lobe hints at a sequence of eruptions within the time frame of the Great Eruption from 1837-1858 or possibly a later shock/reverse shock velocity separation. Our 3D morpho-kinematic modeling and the MUSE observations constitute an invaluable dataset to be confronted with future radiation-hydrodynamics simulations. Such a comparison may shed light on the yet elusive physical mechanism responsible for η Car-like eruptions. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 094.D-0215(A).

Miocene stratigraphy and structure of Sabine Pass, West Cameron, and East Cameron outer continental shelf areas, Louisiana

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

Yang, S.Y.; Watkins, J.S.

Mapping of Miocene stratigraphy and structure of the Sabine Pass, West Cameron, and East Cameron areas of the western Louisiana outer continental shelf - based on over 1300 mi of seismic data on a 4-mi grid, paleotops from 60 wells, and logs from 35 wells - resulted in time-structure and isochron maps at six intervals from the upper Pliocene to lower Miocene. The most pronounced structural features are the fault systems, which trend east-northeast to east along the Miocene stratigraphic trend. Isolated normal faults with small displacements characterize the inner inner shelf, whereas interconnected faults with greater displacements characterize themore » outer inner shelf. The inner inner shelf faults exhibit little growth, but expansion across the interconnected outer inner shelf fault ranges up to 1 sec two-way traveltime. The interconnected faults belong to two structurally independent fault families. The innermost shelf faults appear to root in the sediment column. A third set of faults located in the Sabine Pass area trends north-south. This fault set is thought to be related to basement movement and/or basement structure. Very little salt is evident in the area. A single diapir is located in West Cameron Block 110 and vicinity. There is little evidence of deep salt. Overall sediment thickness probably exceeds 20,000 ft, with the middle Miocene accounting for 8000 ft.« less

The carbon budget in the outer solar nebula.

PubMed

Simonelli, D P; Pollack, J B; McKay, C P; Reynolds, R T; Summers, A L

1989-01-01

Detailed models of the internal structures of Pluto and Charon, assuming rock and water ice as the only constituents, indicate that the mean silicate mass fraction of this two-body system is on the order of 0.7; thus the Pluto/Charon system is significantly "rockier" than the satellites of the giant planets (silicate mass fraction approximately 0.55). This compositional contrast reflects different formation mechanisms: it is likely that Pluto and Charon formed directly from the solar nebula, while the circumplanetary nebulae that produced the giant planet satellites were derived from envelopes that surrounded the forming giant planets (envelopes in which icy planetesimals dissolved more readily than rocky planetesimals). Simple cosmic abundance calculations, and the assumption that the Pluto/Charon system formed directly from solar nebula condensates, strongly suggest that the majority of the carbon in the outer solar nebula was in the form of carbon monoxide; these results are consistent with (1) inheritance from the dense molecular clouds in the interstellar medium (where CH4/CO < 10(-2) in the gas phase) and/or (2) of the Lewis and Prinn kinetic inhibition model of solar nebula chemistry. Theoretical predictions of the C/H enhancements in the atmospheres of the giant planets, when compared to the actual observed enhancements, suggest that 10%, or slightly more, of the carbon in the outer solar nebula was in the form of condensed materials (although the amount of condensed C may have dropped slightly with increasing heliocentric distance). Strict compositional limits computed for the Pluto/Charon system using the densities of CH4 and CO ices indicate that these pure ices are at best minor components in the interiors of these bodies, and imply that CH4 and CO ices were not the dominant C-bearing solids in the outer nebula. Clathrate-hydrates could not have appropriated enough CH4 or CO to be the major form of condensed carbon, although such clathrates may be necessary to explain the presence of methane on Pluto after its formation from a CO-rich nebula. Laboratory studies of carbonaceous chondrites, and spacecraft observations of Comet Halley, strongly suggest that of the remaining possibilities, organic material, rather than elemental carbon, is the most likely candidate for the dominant C-bearing solid in the outer solar nebula. We conclude that the majority of the carbon in the outer solar nebula was in gaseous CO; 10% to a few tens of percent of the C was in condensed organic materials; and at least a trace amount of carbon was in methane gas.

Testing of a femtosecond pulse laser in outer space

PubMed Central

Lee, Joohyung; Lee, Keunwoo; Jang, Yoon-Soo; Jang, Heesuk; Han, Seongheum; Lee, Sang-Hyun; Kang, Kyung-In; Lim, Chul-Woo; Kim, Young-Jin; Kim, Seung-Woo

2014-01-01

We report a test operation of an Er-doped fibre femtosecond laser which was conducted for the first time in outer space. The fibre-based ultrashort pulse laser payload was designed to meet space-use requirements, undergone through ground qualification tests and finally launched into a low-earth orbit early in 2013. Test results obtained during a one-year mission lifetime confirmed stable mode-locking all the way through although the radiation induced attenuation (RIA) in the Er-doped gain fibre caused an 8.6% reduction in the output power. This successful test operation would help facilitate diverse scientific and technological applications of femtosecond lasers in space and earth atmosphere in the near future. PMID:24875665

Testing of a femtosecond pulse laser in outer space.

PubMed

Lee, Joohyung; Lee, Keunwoo; Jang, Yoon-Soo; Jang, Heesuk; Han, Seongheum; Lee, Sang-Hyun; Kang, Kyung-In; Lim, Chul-Woo; Kim, Young-Jin; Kim, Seung-Woo

2014-05-30

We report a test operation of an Er-doped fibre femtosecond laser which was conducted for the first time in outer space. The fibre-based ultrashort pulse laser payload was designed to meet space-use requirements, undergone through ground qualification tests and finally launched into a low-earth orbit early in 2013. Test results obtained during a one-year mission lifetime confirmed stable mode-locking all the way through although the radiation induced attenuation (RIA) in the Er-doped gain fibre caused an 8.6% reduction in the output power. This successful test operation would help facilitate diverse scientific and technological applications of femtosecond lasers in space and earth atmosphere in the near future.

Engaging space: extraterrestrial architecture and the human psyche

NASA Astrophysics Data System (ADS)

Marie Seguin, Angel

2005-05-01

The human fascination with exploring and inhabiting the space that lies beyond Earth's atmosphere continues to grow. Nevertheless, 40 years of experience to date have clearly established that humans in outer space routinely suffer significant psychological impairment arising from their stressful extraterrestrial living conditions. This paper explores those extraterrestrial conditions through the interactions between the extraordinarily harsh environment of outer space, the sensations that humans encounter in space, and the qualities of a habitat that physically interposes itself between the two. The objective of this paper is to develop a habitat that expresses the extraterrestrial condition while supporting the mental health of its inhabitants, so as to augment the success of prolonged extraterrestrial residence and interplanetary travel.

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.

Adaptive imaging through far-field turbulence

NASA Astrophysics Data System (ADS)

Troxel, Steven E.; Welsh, Byron M.; Roggemann, Michael C.

1993-11-01

This paper presents a new method for calculating the field angle dependent average OTF of an adaptive optic system and compares this method to calculations based on geometric optics. Geometric optics calculations are shown to be inaccurate due to the diffraction effects created by far-field turbulence and the approximations made in the atmospheric parameters. Our analysis includes diffraction effects and properly accounts for the effect of the atmospheric turbulence scale sizes. We show that for any atmospheric C(superscript 2)(subscript n) profile, the actual OTF is always better than the OTF calculated using geometric optics. The magnitude of the difference between the calculation methods is shown to be dependent on the amount of far- field turbulence and the values of the outer scale dimension.

Segmented inlet nozzle for gas turbine, and methods of installation

DOEpatents

Klompas, Nicholas

1985-01-01

A gas turbine nozzle guide vane assembly is formed of individual arcuate nozzle segments. The arcuate nozzle segments are elastically joined to each other to form a complete ring, with edges abutted to prevent leakage. The resultant nozzle ring is included within the overall gas turbine stationary structure and secured by a mounting arrangement which permits relative radial movement at both the inner and outer mountings. A spline-type outer mounting provides circumferential retention. A complete rigid nozzle ring with freedom to "float" radially results. Specific structures are disclosed for the inner and outer mounting arrangements. A specific tie-rod structure is also disclosed for elastically joining the individual nozzle segments. Also disclosed is a method of assembling the nozzle ring subassembly-by-subassembly into a gas turbine employing temporary jacks.

Overview of the 6 Meter HIAD Inflatable Structure and Flexible TPS Static Load Test Series

NASA Technical Reports Server (NTRS)

Swanson, Greg; Kazemba, Cole; Johnson, Keith; Calomino, Anthony; Hughes, Steve; Cassell, Alan; Cheatwood, Neil

2014-01-01

To support NASAs long term goal of landing humans on Mars, technologies which enable the landing of heavy payloads are being developed. Current entry, decent, and landing technologies are not practical for this class of payloads due to geometric constraints dictated by current launch vehicle fairing limitations. Therefore, past and present technologies are now being explored to provide a mass and volume efficient solution to atmospheric entry, including Hypersonic Inflatable Aerodynamic Decelerators (HIADs). At the beginning of 2014, a 6m HIAD inflatable structure with an integrated flexible thermal protection system (TPS) was subjected to a static load test series to verify the designs structural performance. The 6m HIAD structure was constructed in a stacked toroid configuration using nine inflatable torus segments composed of fiber reinforced thin films, which were joined together using adhesives and high strength textile woven structural straps to help distribute the loads throughout the inflatable structure. The 6m flexible TPS was constructed using multiple layers of high performance materials to protect the inflatable structure from heat loads that would be seen during atmospheric entry. To perform the static load test series, a custom test fixture was constructed. The fixture consisted of a structural tub rim with enough height to allow for displacement of the inflatable structure as loads were applied. The bottom of the tub rim had an airtight seal with the floor. The centerbody of the inflatable structure was attached to a pedestal mount as seen in Figure 1. Using an impermeable membrane seal draped over the test article, partial vacuum was pulled beneath the HIAD, resulting in a uniform static pressure load applied to the outer surface. During the test series an extensive amount of instrumentation was used to provide many data sets including: deformed shape, shoulder deflection, strap loads, cord loads, inflation pressures, and applied static load.In this overview, the 6m HIAD static load test series will be discussed in detail, including the 6m HIAD inflatable structure and flexible TPS design, test setup and execution, and finally initial results and conclusions from the test series.

The Large-scale Coronal Structure of the 2017 August 21 Great American Eclipse: An Assessment of Solar Surface Flux Transport Model Enabled Predictions and Observations

NASA Astrophysics Data System (ADS)

Nandy, Dibyendu; Bhowmik, Prantika; Yeates, Anthony R.; Panda, Suman; Tarafder, Rajashik; Dash, Soumyaranjan

2018-01-01

On 2017 August 21, a total solar eclipse swept across the contiguous United States, providing excellent opportunities for diagnostics of the Sun’s corona. The Sun’s coronal structure is notoriously difficult to observe except during solar eclipses; thus, theoretical models must be relied upon for inferring the underlying magnetic structure of the Sun’s outer atmosphere. These models are necessary for understanding the role of magnetic fields in the heating of the corona to a million degrees and the generation of severe space weather. Here we present a methodology for predicting the structure of the coronal field based on model forward runs of a solar surface flux transport model, whose predicted surface field is utilized to extrapolate future coronal magnetic field structures. This prescription was applied to the 2017 August 21 solar eclipse. A post-eclipse analysis shows good agreement between model simulated and observed coronal structures and their locations on the limb. We demonstrate that slow changes in the Sun’s surface magnetic field distribution driven by long-term flux emergence and its evolution governs large-scale coronal structures with a (plausibly cycle-phase dependent) dynamical memory timescale on the order of a few solar rotations, opening up the possibility for large-scale, global corona predictions at least a month in advance.

Outer layer effects in wind-farm boundary layers: Coriolis forces and boundary layer height

NASA Astrophysics Data System (ADS)

Allaerts, Dries; Meyers, Johan

2015-11-01

In LES studies of wind-farm boundary layers, scale separation between the inner and outer region of the atmospheric boundary layer (ABL) is frequently assumed, i.e., wind turbines are presumed to fall within the inner layer and are not affected by outer layer effects. However, modern wind turbine and wind farm design tends towards larger rotor diameters and farm sizes, which means that outer layer effects will become more important. In a prior study, it was already shown for fully-developed wind farms that the ABL height influences the power performance. In this study, we use the in-house LES code SP-Wind to investigate the importance of outer layer effects on wind-farm boundary layers. In a suite of LES cases, the ABL height is varied by imposing a capping inversion with varying inversion strengths. Results indicate the growth of an internal boundary layer (IBL), which is limited in cases with low inversion layers. We further find that flow deceleration combined with Coriolis effects causes a change in wind direction throughout the farm. This effect increases with decreasing boundary layer height, and can result in considerable turbine wake deflection near the end of the farm. The authors are supported by the ERC (ActiveWindFarms, grant no: 306471). Computations were performed on VSC infrastructiure (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government-department EWI.

A New Perspective on Galaxy Evolution from the Low Density Outskirts of Galaxies

NASA Astrophysics Data System (ADS)

Emery Watkins, Aaron

2017-01-01

In order to investigate the nature of galaxy outskirts, we carried out a deep imaging campaign of several nearby ($D\\lesssim$10Mpc) galaxies, across a range of environments. We found that most of the galaxies we imaged show red and non-star-forming outer disks, implying evolved stellar populations. Such populations in outer disks are expected as the result of radial migration, yet through Fourier analysis we found no evidence of extended spiral structure in these galaxies. Without star formation or outer spiral structure, it is difficult to determine how these outer disks formed. To investigate the effects of interactions on outer disks, we also observed the Leo I Group; however, while group environments are expected to promote frequent interactions, we found only three extremely faint tidal streams, implying a calm interaction history. As Leo I is fairly low density, this implies that loose groups are ineffective at producing intragroup light (IGL). In the famous interacting system M51, we found that its extended tidal features show similarly red colors as the typical outer disks we observed, implying that M51 had a similar outer disk prior to the interaction, and that the interaction induced no extended star formation, including in the system's HI tail. Therefore, to investigate the nature of star formation in low-density environments, we carried out deep narrow-band H$\\alpha$ imaging of M101 and M51.

Cassini's Ring Grazing and Grand Finale Orbits: Topping Off an Awesome Mission

NASA Astrophysics Data System (ADS)

Edgington, Scott; Spilker, Linda; Coustenis, Athena

2017-04-01

The Cassini-Huygens mission, a joint collaboration between NASA, ESA, and the Italian Space Agency, is in its last year of operations after nearly 13 years in orbit around Saturn. Cassini will send back its final bits of unique data on September 15th, 2017 as it plunges into Saturn's atmosphere, vaporizing and satisfying planetary protection requirements. Before that time Cassini will continue its legacy of exploration and discovery in 2017 and return unique science data provided by orbits taking the spacecraft into unexplored regions near Saturn and its rings. From the new vantage points, Cassini will continue to study seasonal and temporal changes in the system as northern summer solstice approaches. With the exception of one remaining targeted Titan flyby, all of Cassini's close icy satellite flybys, including those of Enceladus, are now completed. In November 2016, Cassini transitioned to a series of orbits with peripases just outside Saturn's F ring. These 20 orbits include close flybys of some tiny ring moons and excellent views of the F ring and Saturn's outer A ring. The 126th and final close flyby of Titan will propel Cassini across Saturn's main rings and into its Grand Finale series of orbits. Cassini's Grand Finale, starting in April 2017, is comprised of 22 orbits at an inclination of 63 degrees. Cassini will repeatedly dive between Saturn's innermost rings and upper atmosphere providing insights into fundamental questions unattainable during the rest of the mission. Cassini will be the first spacecraft to explore this region. These close orbits provide the highest resolution observations of both the rings and Saturn, and direct in-situ sampling of the ring particles, composition, plasma, Saturn's exosphere and the innermost radiation belts. Saturn's gravitational field will be measured to unprecedented accuracy, providing information on the interior structure of the planet, winds in the outer layers of Saturn's atmosphere, and the mass distribution in the rings. Probing the magnetic field will give insight into the nature of the magnetic dynamo, telling us: why the magnetic field is weak; why it exhibits little, if any, axial tilt; and the true rotation rate of the planet. The ion and neutral mass spectrometer will sniff the exosphere and upper atmosphere for molecules that escape the atmosphere itself and water-based molecules originating from the rings. The cosmic dust analyzer will sample the composition of particles from different parts of the main rings. Until the execution of these final orbits, the answers to such new questions will remain mysteries. The science highlights of Cassini's Grand Finale orbits will be discussed. This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2017 California Institute of Technology. Government sponsorship is acknowledged.

Swirling structure for mixing two concentric fluid flows at nozzle outlet

DOEpatents

Mensink, Daniel L.

1993-01-01

A nozzle device for causing two fluids to mix together. In particular, a spray nozzle comprise two hollow, concentric housings, an inner housing and an outer housing. The inner housing has a channel formed therethrough for a first fluid. Its outer surface cooperates with the interior surface of the outer housing to define the second channel for a second fluid. The outer surface of the inner housing and the inner surface of the outer housing each carry a plurality of vanes that interleave but do not touch, each vane of one housing being between two vanes of the other housing. The vanes are curved and the inner surface of the outer housing and the outer surface of the inner housing converge to narrow the second channel. The shape of second channel results in a swirling, accelerating second fluid that will impact the first fluid just past the end of the nozzle where mixing will take place.

Solar activity during the deep minimum of 2009

NASA Astrophysics Data System (ADS)

Sylwester, Janusz; Siarkowski, Marek; Gburek, Szymon; Gryciuk, Magdalena; Kepa, Anna; Kowaliński, Mirosław; Mrozek, Tomek; Phillips, Kenneth J. H.; Podgórski, Piotr; Sylwester, Barbara

2014-12-01

We discuss the character of the unusually deep solar activity minimum of 2009 between Solar Cycles 23 and 24. Levels of solar activity in various parts of the solar atmosphere -- photosphere, chromosphere, transition region, and corona -- were observed to be at their lowest for a century. The soft X-ray emission from the corona (hot outer part of the Sun's atmosphere) was measured throughout most of 2009 with the Polish-built SphinX spectrophotometer. Unlike other X-ray monitoring spacecraft, this sensitive spacecraft-borne instrument was able to continue measurements throughout this extended period of low activity.

On the theory of coronal heating mechanisms

NASA Technical Reports Server (NTRS)

Kuperus, M.; Ionson, J. A.; Spicer, D. S.

1980-01-01

Theoretical models describing solar coronal heating mechanisms are reviewed in some detail. The requirements of chromospheric and coronal heating are discussed in the context of the fundamental constraints encountered in modelling the outer solar atmosphere. Heating by acoustic processes in the 'nonmagnetic' parts of the atmosphere is examined with particular emphasis on the shock wave theory. Also discussed are theories of heating by electrodynamic processes in the magnetic regions of the corona, either magnetohydrodynamic waves or current heating in the regions with large electric current densities (flare type heating). Problems associated with each of the models are addressed.

Forming Super-Puffs Beyond 1 AU

NASA Astrophysics Data System (ADS)

Lee, Eve J.; Chiang, Eugene

2017-06-01

Super-puffs are an uncommon class of short-period planets seemingly too voluminous for their small masses (4-10 Rearth, 2-6 Mearth). Super-puffs most easily acquire their thick atmospheres as dust-free, rapidly cooling worlds outside ˜1AU where nebular gas is colder, less dense, and therefore less opaque. These puffy planets probably migrated in to their current orbits; they are expected to form the outer links of mean-motion resonant chains, and to exhibit atmospheric characteristics consistent with formation at large distances. I will also discuss, in general, how densities of planets can be used to infer their formation locations.

REVIEWS OF TOPICAL PROBLEMS: Astrophysical and laboratory applications of self-alignment

NASA Astrophysics Data System (ADS)

Kazantsev, S. A.

1983-04-01

Self-alignment of excited atoms which is observed in the laboratory and in astrophysical situations is reviewed. It is described classically and in terms of quantum mechanics. Astrophysical manifestations of selfalignment of excited atoms in the solar atmosphere and applications of self-alignment in magnetometry are analyzed. Self-alignment in low-pressure gas-discharge plasmas in the laboratory is described in detail. The cross sections for depolarizing collisions measured by this method are tabulated along with the lifetimes of excited inert gas atoms. These atomic constants can be used in practical magnetometry of the outer solar atmosphere.

Evolution of space food in Nostoc sp. HK-01

NASA Astrophysics Data System (ADS)

Tomita-Yokotani, Kaori; Yamashita, Masamichi; Hashimoto, Hirofumi; Sato, Seigo; Kimura, Yasuko; Katoh, Hiroshi; Arai, Mayumi

2012-07-01

Habitation in outer space is one of our challenges. We have been studying future space agriculture to provide food and oxygen for the habitation area in the space environment, on Mars. A cyanobacteria, Nostoc sp. HK-01, has high several outer space environmental tolerance. We have already confirmed that Nostoc sp.HK-01 had an ability to grow for over several years on the Martian regolith simulant in a laboratory experiment. Nostoc sp HK-01 would have high contribution to change the atmosphere in Mars as a photosynthetic creature. In outer environment, all of materials have to circulate for all of creature living in artificial eco-systems on Mars. This material has several functions as the utilization in space agriculture. Here, we are proposing using them as a food after its growing on Mars. We are trying to determine the best conditions and evolution for space food using Nostoc sp.HK-01 and studying the proposal of utilization of cyanobacteria, Nostoc sp HK-01, for the variation of meal as space agriculture.

Freeform Deposition Method for Coolant Channel Closeout

NASA Technical Reports Server (NTRS)

Gradl, Paul R. (Inventor); Reynolds, David Christopher (Inventor); Walker, Bryant H. (Inventor)

2017-01-01

A method is provided for fabricating a coolant channel closeout jacket on a structure having coolant channels formed in an outer surface thereof. A line of tangency relative to the outer surface is defined for each point on the outer surface. Linear rows of a metal feedstock are directed towards and deposited on the outer surface of the structure as a beam of weld energy is directed to the metal feedstock so-deposited. A first angle between the metal feedstock so-directed and the line of tangency is maintained in a range of 20-90.degree.. The beam is directed towards a portion of the linear rows such that less than 30% of the cross-sectional area of the beam impinges on a currently-deposited one of the linear rows. A second angle between the beam and the line of tangency is maintained in a range of 5-65 degrees.

Aircraft engine with inter-turbine engine frame supported counter rotating low pressure turbine rotors

NASA Technical Reports Server (NTRS)

Seda, Jorge F. (Inventor); Dunbar, Lawrence W. (Inventor); Gliebe, Philip R. (Inventor); Szucs, Peter N. (Inventor); Brauer, John C. (Inventor); Johnson, James E. (Inventor); Moniz, Thomas (Inventor); Steinmetz, Gregory T. (Inventor)

2003-01-01

An aircraft gas turbine engine assembly includes an inter-turbine frame axially located between high and low pressure turbines. Low pressure turbine has counter rotating low pressure inner and outer rotors with low pressure inner and outer shafts which are at least in part rotatably disposed co-axially within a high pressure rotor. Inter-turbine frame includes radially spaced apart radially outer first and inner second structural rings disposed co-axially about a centerline and connected by a plurality of circumferentially spaced apart struts. Forward and aft sump members having forward and aft central bores are fixedly joined to axially spaced apart forward and aft portions of the inter-turbine frame. Low pressure inner and outer rotors are rotatably supported by a second turbine frame bearing mounted in aft central bore of aft sump member. A mount for connecting the engine to an aircraft is located on first structural ring.

Staged fuel and air injection in combustion systems of gas turbines

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

Hughes, Michael John; Berry, Jonathan Dwight

A gas turbine including a working fluid flowpath extending aftward from a forward injector in a combustor. The combustor may include an inner radial wall, an outer radial wall, and, therebetween, a flow annulus, and a third radial wall formed about the outer radial wall that forms an outer flow annulus. A staged injector may intersect the flow annulus so to attain an injection point within the working fluid flowpath by which aftward and forward annulus sections are defined. Air directing structure may include an aftward intake section corresponding to the aftward annulus section and a forward intake section correspondingmore » to the forward annulus section. The air directing structure may include a switchback coolant flowpath to direct air from the compressor discharge cavity to the staged injector. The switchback coolant flowpath may include an upstream section through the flow annulus, and a downstream section through the outer flow annulus.« less

Structure of Rotavirus Outer-Layer Protein VP7 Bound with a Neutralizing Fab

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

Aoki, Scott T.; Settembre, Ethan C.; Trask, Shane D.

2009-06-17

Rotavirus outer-layer protein VP7 is a principal target of protective antibodies. Removal of free calcium ions (Ca{sup 2+}) dissociates VP7 trimers into monomers, releasing VP7 from the virion, and initiates penetration-inducing conformational changes in the other outer-layer protein, VP4. We report the crystal structure at 3.4 angstrom resolution of VP7 bound with the Fab fragment of a neutralizing monoclonal antibody. The Fab binds across the outer surface of the intersubunit contact, which contains two Ca{sup 2+} sites. Mutations that escape neutralization by other antibodies suggest that the same region bears the epitopes of most neutralizing antibodies. The monovalent Fab ismore » sufficient to neutralize infectivity. We propose that neutralizing antibodies against VP7 act by stabilizing the trimer, thereby inhibiting the uncoating trigger for VP4 rearrangement. A disulfide-linked trimer is a potential subunit immunogen.« less

The Whole Heliosphere Interval: Campaign Summaries and Early Results

NASA Technical Reports Server (NTRS)

Thompson, Barbara J.; Gibson, Sarah E.; Kozyra, Janet U.

2008-01-01

The Whole Heliosphere Interval (WHI) is an internationally coordinated observing and modeling effort to characterize the 3-dimensional interconnected solar-heliospheric-planetary system - a.k.a. the "heliophysical" system. The heart of the WHI campaign is the study of the interconnected 3-D heliophysical domain, from the interior of the Sun, to the Earth, outer planets, and into interstellar space. WHI observing campaigns began with the 3-0 solar structure from solar Carrington Rotation 2068, which ran from March 20 - April 16, 2008. Observations and models of the outer heliosphere and planetary impacts extended beyond those dates as necessary; for example, the solar wind transit time to outer planets can take months. WHI occurs during solar minimum, which optimizes our ability to characterize the 3-D heliosphere and trace the structure to the outer limits of the heliosphere. A summary of some of the key results from the WHI first workshop in August 2008 will be given.

Uranus science planning. [considering Mariner Jupiter-Uranus mission

NASA Technical Reports Server (NTRS)

Moore, J.

1974-01-01

Recommendations for a 1979 Mariner Jupiter-Uranus mission are discussed with the possibility of launching the first outer planet atmospheric entry probe. Measurement categories considered for the mission include conducting imaging experiments, observations in both the IR and UV spectral range, experiments associated with magnetic fields, plasma, charged particles, and S- and X-band occultation measurements.

The lipopolysaccharide lipid-a long chain fatty acid is important for rhizobium leguminosarum growth and stress adaptation in free-living and nodule environments

USDA-ARS?s Scientific Manuscript database

Rhizobium bacteria live in soil and plant environments, are capable of inducing symbiotic nodules on legumes, invade these nodules, and develop into bacteroids that fix atmospheric nitrogen into ammonium. Lipopolysaccharide (LPS) is anchored in the bacterial outer membrane through a specialized lipi...

Polycyclic aromatic hydrocarbons in the atmospheres of Titan and Jupiter

NASA Technical Reports Server (NTRS)

Sagan, Carl; Khare, B. N.; Thompson, W. R.; Mcdonald, G. D.; Wing, Michael R.; Bada, Jeffrey L.; Vo-Dinh, Tuan; Arakawa, E. T.

1993-01-01

PAHs are important components of the interstellar medium and carbonaceous chondrites, but have never been identified in the reducing atmospheres of the outer solar system. Incompletely characterized complex organic solids (tholins) produced by irradiating simulated Titan atmospheres reproduce well the observed UV/visible/IR optical constants of the Titan stratospheric haze. Titan tholin and a tholin generated in a crude simulation of the atmosphere of Jupiter are examined by two-step laser desorption/multiphoton ionization mass spectrometry. A range of two- to four-ring PAHs, some with one to four alkylation sites, are identified, with a net abundance of about 0.0001 g/g (grams per gram) of tholins produced. Synchronous fluorescence techniques confirm this detection. Titan tholins have proportionately more one- and two-ring PAHs than do Jupiter tholins, which in turn have more four-ring and larger PAHs. The four-ringed PAH chrysene, prominent in some discussions of interstellar grains, is found in Jupiter tholins.

REVIEWS OF TOPICAL PROBLEMS: Gas lasers with solar excitation

NASA Astrophysics Data System (ADS)

Gordiets, B. F.; Panchenko, Vladislav Ya

1986-07-01

CONTENTS 1. Introduction 703 2. General requirements for laser media using solar excitation 704 3. Lasers with direct excitation by solar light 705 3.1. Basic characteristics of laser media. 3.2. Photodissociation Br2-CO2 lasers. 3.3. Interhalogen molecule lasers. 3.4. Iodine lasers. 3.5. Alkali metal vapor lasers. 4. Lasers with thermal conversion of solar pumping 709 4.1. General considerations. 4.2. CO2 laser with excitation in a black body cavity and with gas flow. 4.3. cw CO2 laser without gas flow. 5. Space laser media with solar excitation 713 5.1. Population inversion of molecular levels in the outer atmosphere of the Earth. 5.2. Laser effect in the atmospheres of Venus and Mars. 5.3. Terrestrial experimental technique for observing infrared emission in the atmospheres of planets. 5.4. Designs for laser systems in the atmospheres of Venus and Mars. 6. Conclusions 717 References 717

Theory of nanotube faraday cage

NASA Astrophysics Data System (ADS)

Roxana Margine, Elena; Nisoli, Cristiano; Kolmogorov, Aleksey; Crespi, Vincent H.

2003-03-01

Charge transfer between dopants and double-wall carbon nanotubes is examined theoretically. We model the system as a triple cylindrical capacitor with the dopants forming a shell around the outer wall of the nanotube. The total energy of the system contains three terms: the band structure energies of the inner and outer tube, calculated in a tight-binding model with rigid bands, and the electrostatic energy of the tri-layer distribution. Even for metallic inner and outer tube walls, wherein the diameter dependence of the bandgap does not favor the outer wall, nearly all of the dopant charge resides on the outer layer, a nanometer-scale Faraday cage. The calculated charge distribution is in agreement with recent experimental measurements.

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.

The Sun at high spatial resolution: The physics of small spatial structures in a magnetized medium

NASA Technical Reports Server (NTRS)

Rosner, R. T.

1986-01-01

An attempt is made to provide a perspective on the problem of spatial structuring on scales smaller than can presently be directly and regularly observed from the ground or with which current space-based instrumentation can be anticipated. There is abundant evidence from both observations and theory that such spatial structuring of the solar outer atmosphere is ubiquitous not only on the observed scales, but also on spatial scales down to (at least) the subarcsecond range. This is not to say that the results to be obtained from observations on these small scales can be anticipated: quite the opposite. What is clear instead is that many of the classic problems of coronal and chromospheric activity - involving the basic dissipative nature of magnetized plasmas - will be seen from a novel perspective at these scales, and that there are reasons for believing that dynamical processes of importance to activity on presently-resolved scales will themselves begin to be resolved on the sub-arcsecond level. Since the Sun is the only astrophysical laboratory for which there is any hope of studying these processes in any detail, this observatioinal opportunity is an exciting prospect for any student of magnetic activity in astrophysics.

The Nonbarred Double-Ringed Galaxy, PGC 1000714

NASA Astrophysics Data System (ADS)

Seigar, Marc; Mutlu Pakdil, Burcin; Mangedarage, Mithila; Treuthardt, Patrick M.

2017-01-01

Hoag-type galaxies are rare peculiar systems which bear strong resemblance to Hoag's Object with an elliptical-like core, a detached outer ring, and no signs of a bar or stellar disk. They represent extreme cases and help us understand the formation of galaxies in general by providing clues on formation mechanisms. The nature of outer rings in Hoag-type galaxies is still debated and may be related either to slow secular evolution, such as dissolution of a barlike structure or to environmental processes, such as galaxy-galaxy interactions or gas infall. Due to a fairly superficial resemblance to Hoag's Object, PGC 1000714 is a good target for detailed study of the peculiar structure of this type. We present the first photometric study of PGC 1000714 that has not yet been described in the literature. Our aim is to evaluate its structure and properties as well as understand the origin of outer rings in such galaxies. Surface photometry of the central body is performed using near-UV, BVRI and JHK images. Based on the photometric data, the nearly round central body follows a de Vaucouleurs profile almost all the way to the center. The detailed photometry reveals a reddish inner ring-shaped structure that shares the same center as the central body. However, no sign of a bar or stellar disk is detected. The outer ring appears as a bump in the surface brightness profile with a peak brightness of 25.8 mag/arcsec^{2} in the B-band and shows no sharp outer boundary. By reconstructing the observed SED for the central body and the rings, we recover the stellar population properties of the galaxy components. Our work suggests different formation histories for the inner and outer rings. We rule out the secular evolution model as being a formation mechanism for the outer ring. The colors of the outer ring are consistent with a feature that may have experienced a burst of star formation due to a possible recent accretion event. In addition, our work supports that the central body may be formed by a relatively dry major merger or in a single, short and highly effective star formation burst, and the inner ring may be formed as a result of intergalactic medium accretion or secular evolution of a possible gaseous disk

Brain oxygen tension controls the expansion of outer subventricular zone-like basal progenitors in the developing mouse brain.

PubMed

Wagenführ, Lisa; Meyer, Anne K; Braunschweig, Lena; Marrone, Lara; Storch, Alexander

2015-09-01

The mammalian neocortex shows a conserved six-layered structure that differs between species in the total number of cortical neurons produced owing to differences in the relative abundance of distinct progenitor populations. Recent studies have identified a new class of proliferative neurogenic cells in the outer subventricular zone (OSVZ) in gyrencephalic species such as primates and ferrets. Lissencephalic brains of mice possess fewer OSVZ-like progenitor cells and these do not constitute a distinct layer. Most in vitro and in vivo studies have shown that oxygen regulates the maintenance, proliferation and differentiation of neural progenitor cells. Here we dissect the effects of fetal brain oxygen tension on neural progenitor cell activity using a novel mouse model that allows oxygen tension to be controlled within the hypoxic microenvironment in the neurogenic niche of the fetal brain in vivo. Indeed, maternal oxygen treatment of 10%, 21% and 75% atmospheric oxygen tension for 48 h translates into robust changes in fetal brain oxygenation. Increased oxygen tension in fetal mouse forebrain in vivo leads to a marked expansion of a distinct proliferative cell population, basal to the SVZ. These cells constitute a novel neurogenic cell layer, similar to the OSVZ, and contribute to corticogenesis by heading for deeper cortical layers as a part of the cortical plate. © 2015. Published by The Company of Biologists Ltd.

Small Nuclear-powered Hot Air Balloons for the Exploration of the Deep Atmosphere of Uranus and Neptune

NASA Astrophysics Data System (ADS)

Van Cleve, J. E.; Grillmair, C. J.

2001-01-01

The Galileo probe gathered data in the Jovian atmosphere for about one hour before its destruction. For a wider perceptive on the atmospheres of the outer planets, multiple, long-lived observations platforms would be useful. In this paper we examine the basic physics of hot-air ballooning in a hydrogen atmosphere, using plutonium RTGs as a heat source. We find that such balloons are buoyant at a sufficiently great depth in these atmospheres, and derive equations for the balloon radius and mass of plutonium required as a function of atmospheric mass density and balloon material parameters. We solve for the buoyancy depth given the constraint that each probe may contain 1.0 kg of Pu, and find that the temperature at that depth is too great for conventional electronics (>70 C) for Jupiter and Saturn. However, the Pu mass constraint and the operating temperature constraint are consistent for Uranus and Neptune, and this concept may be applicable to those planets. Additional information is contained in the original extended abstract.

Glu-311 in External Loop 4 of the Sodium/Proline Transporter PutP Is Crucial for External Gate Closure.

PubMed

Bracher, Susanne; Guérin, Kamila; Polyhach, Yevhen; Jeschke, Gunnar; Dittmer, Sophie; Frey, Sabine; Böhm, Maret; Jung, Heinrich

2016-03-04

The available structural information on LeuT and structurally related transporters suggests that external loop 4 (eL4) and the outer end of transmembrane domain (TM) 10' participate in the reversible occlusion of the outer pathway to the solute binding sites. Here, the functional significance of eL4 and the outer region of TM10' are explored using the sodium/proline symporter PutP as a model. Glu-311 at the tip of eL4, and various amino acids around the outer end of TM10' are identified as particularly crucial for function. Substitutions at these sites inhibit the transport cycle, and affect in part ligand binding. In addition, changes at selected sites induce a global structural alteration in the direction of an outward-open conformation. It is suggested that interactions between the tip of eL4 and the peptide backbone at the end of TM10' participate in coordinating conformational alterations underlying the alternating access mechanism of transport. Together with the structural information on LeuT-like transporters, the results further specify the idea that common design and functional principles are maintained across different transport families. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Glu-311 in External Loop 4 of the Sodium/Proline Transporter PutP Is Crucial for External Gate Closure*

PubMed Central

Bracher, Susanne; Guérin, Kamila; Polyhach, Yevhen; Jeschke, Gunnar; Dittmer, Sophie; Frey, Sabine; Böhm, Maret; Jung, Heinrich

2016-01-01

The available structural information on LeuT and structurally related transporters suggests that external loop 4 (eL4) and the outer end of transmembrane domain (TM) 10′ participate in the reversible occlusion of the outer pathway to the solute binding sites. Here, the functional significance of eL4 and the outer region of TM10′ are explored using the sodium/proline symporter PutP as a model. Glu-311 at the tip of eL4, and various amino acids around the outer end of TM10′ are identified as particularly crucial for function. Substitutions at these sites inhibit the transport cycle, and affect in part ligand binding. In addition, changes at selected sites induce a global structural alteration in the direction of an outward-open conformation. It is suggested that interactions between the tip of eL4 and the peptide backbone at the end of TM10′ participate in coordinating conformational alterations underlying the alternating access mechanism of transport. Together with the structural information on LeuT-like transporters, the results further specify the idea that common design and functional principles are maintained across different transport families. PMID:26728461

Fourier transform spectroscopy for future planetary missions

NASA Astrophysics Data System (ADS)

Brasunas, John; Kolasinski, John; Kostiuk, Ted; Hewagama, Tilak

2017-01-01

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, we have developed CIRS-lite, a smaller version of the CIRS FTS for future planetary missions. We discuss the roadmap for making CIRS-lite a viable candidate for future planetary missions, including the recent increased emphasis on ocean worlds (Europa, Encelatus, Titan) and also on smaller payloads such as CubeSats and SmallSats.

Lunar and Planetary Science XXXV: Special Session: Oxygen in the Solar System, I

NASA Technical Reports Server (NTRS)

2004-01-01

The Special Session: Oxygen in the Solar System, I, included the following reports:Oxygen in the Solar System: Origins of Isotopic and Redox Complexity; The Origin of Oxygen Isotope Variations in the Early Solar System; Solar and Solar-Wind Oxygen Isotopes and the Genesis Mission; Solar 18O/17O and the Setting for Solar Birth; Oxygen Isotopes in Early Solar System Materials: A Perspective Based on Microbeam Analyses of Chondrules from CV Carbonaceous Chondrites; Insight into Primordial Solar System Oxygen Reservoirs from Returned Cometary Samples; Tracing Meteorites to Their Sources Through Asteroid Spectroscopy; Redox Conditions Among the Terrestrial Planets; Redox Complexity in Martian Meteorites: Implications for Oxygen in the Terrestrial Planets; Implications of Sulfur Isotopes for the Evolution of Atmospheric Oxygen; Oxygen in the Outer Solar System; and On the Oxidation States of the Galilean Satellites: Implications for Internal Structures.

Rapid Penumbra and Lorentz Force Changes in an X1.0 Solar Flare

NASA Astrophysics Data System (ADS)

Xu, Zhe; Jiang, Yunchun; Yang, Jiayang; Yang, Bo; Bi, Yi

2016-03-01

We present observations of the violent changes in photospheric magnetic structures associated with an X1.1 flare, which occurred in a compact δ-configuration region in the following part of AR 11890 on 2013 November 8. In both central and peripheral penumbra regions of the small δ sunspot, these changes took place abruptly and permanently in the reverse direction during the flare: the inner/outer penumbra darkened/disappeared, where the magnetic fields became more horizontal/vertical. Particularly, the Lorentz force (LF) changes in the central/peripheral region had a downward/upward and inward direction, meaning that the local pressure from the upper atmosphere was enhanced/released. It indicates that the LF changes might be responsible for the penumbra changes. These observations can be well explained as the photospheric response to the coronal field reconstruction within the framework of the magnetic implosion theory and the back reaction model of flares.

Non-Topographic Space-Based Laser Remote Sensing

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Abshire, James B.; Riris, Haris; Purucker, Michael; Janches, Diego; Getty, Stephanie; Krainak, Michael A.; Stephen, Mark A.; Chen, Jeffrey R.; Li, Steve X.;

On the Spectral Evolution of Helium-atmosphere White Dwarfs Showing Traces of Hydrogen

NASA Astrophysics Data System (ADS)

Rolland, B.; Bergeron, P.; Fontaine, G.

2018-04-01

We present a detailed spectroscopic analysis of 115 helium-line (DB) and 28 cool, He-rich hydrogen-line (DA) white dwarfs based on atmosphere fits to optical spectroscopy and photometry. We find that 63% of our DB population show hydrogen lines, making them DBA stars. We also demonstrate the persistence of pure DB white dwarfs with no detectable hydrogen feature at low effective temperatures. Using state-of-the art envelope models, we next compute the total quantity of hydrogen, M H, that is contained in the outer convection zone as a function of effective temperature and atmospheric H/He ratio. We find that some (T eff, M H) pairs cannot physically exist as a homogeneously mixed structure; such a combination can only occur as stratified objects of the DA spectral type. On that basis, we show that the values of M H inferred for the bulk of the DBA stars are too large and incompatible with the convective dilution scenario. We also present evidence that the hydrogen abundances measured in DBA and cool, helium-rich white dwarfs cannot be globally accounted for by any kind of accretion mechanism onto a pure DB star. We suggest that cool, He-rich DA white dwarfs are most likely created by the convective mixing of a DA star with a thin hydrogen envelope; they are not cooled down DBAs. We finally explore several scenarios that could account for the presence of hydrogen in DBA stars.

Mean square hydrogen fluctuations in chitosan/lecithin nanoparticles from elastic neutron scattering experiments

NASA Astrophysics Data System (ADS)

Sonvico, Fabio; Teresa Di Bari, Maria; Bove, Livia; Deriu, Antonio; Cavatorta, Fabrizio; Albanese, Gianfranco

2006-11-01

Recently, we have started a systematic study of the structure and dynamics of nano- and microparticles of interest as highly biocompatible drug carriers. For these particles, that are composed of polymeric and lipid material, a detailed understanding of the particle-solvent interactions is of key importance in order to tailor their characteristics for delivering drugs with specific chemical properties. Here we report results of elastic neutron scattering (ENS) investigations on lecithin/chitosan nanoparticles. They were first prepared by autoassembling the two components in aqueous solution; the samples were then freeze-dried and re-hydrated in a D 2O atmosphere. The experiments were performed in the temperature range of 20-50 K using the backscattering spectrometer IN13 at ILL (Grenoble, France). The comparison of samples in the dry state with similar ones at an hydration level of about 0.3-0.4 (g D 2O/g hydrated sample), indicates that the presence of an outer chitosan ‘‘coating’’ reduces the mean square fluctuations of the hydrogens in the lipid component, leading thus to a stiffer nanoparticle structure.

Hydration behavior of casein micelles in thin film geometry: a GISANS study?

PubMed

Metwalli, E; Moulin, J F; Gebhardt, R; Cubitt, R; Tolkach, A; Kulozik, U; Müller-Buschbaum, P

2009-04-07

The water content of casein micelle films in water vapor atmosphere is investigated using time-resolved grazing incidence small-angle neutron scattering (GISANS). Initial dry casein films are prepared with a spin-coating method. At 30 degrees C, the formation of a water-equilibrated casein protein film is reached after 11 min with a total content of 0.36 g of water/g of protein. With increasing water vapor temperature up to 70 degrees C, an increase in the water content is found. With GISANS, lateral structures on the nanometer scale are resolved during the swelling experiment at different temperatures and modeled using two types of spheres: micelles and mini-micelles. Upon water uptake, molecular assemblies in the size range of 15 nm (mini-micelles) are attributed to the formation of a high-contrast D2O outer shell on the small objects that already exist in the protein film. For large objects (>100 nm), the mean size increases at high D2O vapor temperature because of possible aggregation between hydrated micelles. These results are discussed and compared with various proposed models for casein micelle structures.

Improving the Corrosion Resistance of Biodegradable Magnesium Alloys by Diffusion Coating Process

NASA Astrophysics Data System (ADS)

Levy, Galit Katarivas; Aghion, Eli

Magnesium alloys suffer from accelerated corrosion in physiological environment and hence their use as a structural material for biodegradable implants is limited. The present study focuses on a diffusion coating treatment that amplifies the beneficial effect of Neodymium on the corrosion resistance of magnesium alloys. The diffusion coating layer was obtained by applying 1 µm Nd coating on EW10X04 magnesium alloy using Electron-gun evaporator and PVD process. The coated alloy was heat treated at 350°C for 3 hours in a protective atmosphere of N2+0.2%SF6. The micro structure characteristics were evaluated by SEM, XRD, and XPS; the corrosion resistance was examined by potentiodynamic polarization and EIS analysis. The corrosion resistance of the diffusion coated alloy was significantly improved compared to the uncoated material. This was related to: (i) formation of Nd2O3 in the outer scale, (ii) integration of Nd in the MgO oxide layer, and (iii) formation of secondary phase Mg41Nd5 along the grain boundaries of α-Mg.

Nozzle and shroud assembly mounting structure

DOEpatents

Faulder, Leslie J.; Frey, deceased, Gary A.; Nielsen, Engward W.; Ridler, Kenneth J.

1997-01-01

The present nozzle and shroud assembly mounting structure configuration increases component life and reduces maintenance by reducing internal stress between the mounting structure having a preestablished rate of thermal expansion and the nozzle and shroud assembly having a preestablished rate of thermal expansion being less than that of the mounting structure. The mounting structure includes an outer sealing portion forming a cradling member in which an annular ring member is slidably positioned. The mounting structure further includes an inner mounting portion to which a hooked end of the nozzle and shroud assembly is attached. As the inner mounting portion expands and contracts, the nozzle and shroud assembly slidably moves within the outer sealing portion.

Nozzle and shroud assembly mounting structure

DOEpatents

Faulder, L.J.; Frey, G.A.; Nielsen, E.W.; Ridler, K.J.

1997-08-05

The present nozzle and shroud assembly mounting structure configuration increases component life and reduces maintenance by reducing internal stress between the mounting structure having a preestablished rate of thermal expansion and the nozzle and shroud assembly having a preestablished rate of thermal expansion being less than that of the mounting structure. The mounting structure includes an outer sealing portion forming a cradling member in which an annular ring member is slidably positioned. The mounting structure further includes an inner mounting portion to which a hooked end of the nozzle and shroud assembly is attached. As the inner mounting portion expands and contracts, the nozzle and shroud assembly slidably moves within the outer sealing portion. 3 figs.

Numerical Comparison of Active Acoustic and Structural Noise Control in a Stiffened Double Wall Cylinder

NASA Technical Reports Server (NTRS)

Grosveld, Ferdinand W.

1996-01-01

The active acoustic and structural noise control characteristics of a double wall cylinder with and without ring stiffeners were numerically evaluated. An exterior monopole was assumed to acoustically excite the outside of the double wall cylinder at an acoustic cavity resonance frequency. Structural modal vibration properties of the inner and outer shells were analyzed by post-processing the results from a finite element analysis. A boundary element approach was used to calculate the acoustic cavity response and the coupled structural-acoustic interaction. In the frequency region of interest, below 500 Hz, all structural resonant modes were found to be acoustically slow and the nonresonant modal response to be dominant. Active sound transmission control was achieved by control forces applied to the inner or outer shell, or acoustic control monopoles placed just outside the inner or outer shell. A least mean square technique was used to minimize the interior sound pressures at the nodes of a data recovery mesh. Results showed that single acoustic control monopoles placed just outside the inner or outer shells resulted in better sound transmission control than six distributed point forces applied to either one of the shells. Adding stiffeners to the double wall structure constrained the modal vibrations of the shells, making the double wall stiffer with associated higher modal frequencies. Active noise control obtained for the stiffened double wall configurations was less than for the unstiffened cylinder. In all cases, the acoustic control monopoles controlled the sound transmission into the interior better than the structural control forces.

Formation of ZrO{sub 2} in coating on Mg–3 wt.%Al–1 wt.%Zn alloy via plasma electrolytic oxidation: Phase and structure of zirconia

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

Lee, Kang Min; Kim, Yeon Sung; Yang, Hae Woong

2015-01-15

An investigation of the coating structure formed on Mg–3 wt.%Al–1 wt.%Zn alloy sample subjected to plasma electrolytic oxidation was examined by field-emission transmission electron microscopy. The plasma electrolytic oxidation process was conducted in a phosphoric acid electrolyte containing K{sub 2}ZrF{sub 6} for 600 s. Microstructural observations showed that the coating consisting of MgO, MgF{sub 2}, and ZrO{sub 2} phases was divided into three distinctive parts, the barrier, intermediate, and outer layers. Nanocrystalline MgO and MgF{sub 2} compounds were observed mainly in the barrier layer of ~ 1 μm thick near to the substrate. From the intermediate to outer layers, variousmore » ZrO{sub 2} polymorphs appeared due to the effects of the plasma arcing temperature on the phase transition of ZrO{sub 2} compounds during the plasma electrolytic oxidation process. In the outer layer, MgO compound grew in the form of a dendrite-like structure surrounded by cubic ZrO{sub 2}. - Highlights: • The barrier layer containing MgO and MgF{sub 2} was observed near to the Mg substrate. • In the intermediate layer, m-, t-, and o-ZrO{sub 2} compounds were additionally detected. • The outer layer contained MgO with the dendrite-like structure surrounded by c-ZrO{sub 2}. • The grain sizes of compounds in oxide layer increased from barrier to outer layer.« less

Hubble’s Global View of Jupiter During the Juno Mission

NASA Astrophysics Data System (ADS)

Simon, Amy A.; Wong, Michael H.; Orton, Glenn S.; Cosentino, Richard; Tollefson, Joshua; Johnson, Perianne

2017-10-01

With two observing programs designed for mapping clouds and hazes in Jupiter's atmosphere during the Juno mission, the Hubble Space Telescope is acquiring an unprecedented set of global maps for study. The Outer Planet Atmospheres Legacy program (OPAL, PI: Simon) and the Wide Field Coverage for Juno program (WFCJ, PI: Wong) are designed to enable frequent multi-wavelength global mapping of Jupiter, with many maps timed specifically for Juno’s perijove passes. Filters span wavelengths from 212 to 894 nm. Besides offering global views for Juno observation context, they also reveal a wealth of information about interesting atmospheric dynamical features. We will summarize the latest findings from these global mapping programs, including changes in the Great Red Spot, zonal wind profile analysis, and persistent cyclone-generated waves in the North Equatorial Belt.

Insight into the product film formed on Ni-advanced weathering steel in a tropical marine atmosphere

NASA Astrophysics Data System (ADS)

Wu, Wei; Cheng, Xuequn; Hou, Huaxing; Liu, Bo; Li, Xiaogang

2018-04-01

The product film formed on Ni-advanced weathering steel in a tropical marine environment was investigated in detail through outdoor exposure by using diverse surface analysis techniques combined with electrochemical impedance spectroscopy and scanning kelvin probe measurements. The results showed that the product film was mainly composed of nanophasic goethite in the inner layer and maghemite, akaganeite, and hematite in the outer layer. Moreover, the resistance to atmospheric corrosion gradually increased from the outermost product film to the innermost film. Ni was significantly enriched in the inner layer in the form of the spinel phase NiFe2O4, which transformed lepidocrocite to fine-grained goethite, withstood the invasion of chloridion, and improved the corrosion potential of the product film in a tropical marine atmosphere.

Star Surface Polluted by Planetary Debris

NASA Astrophysics Data System (ADS)

2007-07-01

Looking at the chemical composition of stars that host planets, astronomers have found that while dwarf stars often show iron enrichment on their surface, giant stars do not. The astronomers think that the planetary debris falling onto the outer layer of the star produces a detectable effect in a dwarf star, but this pollution is diluted by the giant star and mixed into its interior. "It is a little bit like a Tiramisu or a Capuccino," says Luca Pasquini from ESO, lead-author of the paper reporting the results. "There is cocoa powder only on the top!' ESO PR Photo 29/07 ESO PR Photo 29/07 The Structure of Stars Just a few years after the discovery of the first exoplanet it became evident that planets are preferentially found around stars that are enriched in iron. Planet-hosting stars are on average almost twice as rich in metals than their counterparts with no planetary system. The immediate question is whether this richness in metals enhances planet formation, or whether it is caused by the presence of planets. The classic chicken and egg problem. In the first case, the stars would be metal-rich down to their centre. In the second case, debris from the planetary system would have polluted the star and only the external layers would be affected by this pollution. When observing stars and taking spectra, astronomers indeed only see the outer layers and can't make sure the whole star has the same composition. When planetary debris fall onto a star, the material will stay in the outer parts, polluting it and leaving traces in the spectra taken. A team of astronomers has decided to tackle this question by looking at a different kind of stars: red giants. These are stars that, as will the Sun in several billion years, have exhausted the hydrogen in their core. As a result, they have puffed up, becoming much larger and cooler. Looking at the distribution of metals in fourteen planet-hosting giants, the astronomers found that their distribution was rather different from normal planet-hosting stars. "We find that evolved stars are not enriched in metals, even when hosting planets," says Pasquini. "Thus, the anomalies found in planet-hosting stars seem to disappear when they get older and puff up!" Looking at the various options, the astronomers conclude that the most likely explanation lies in the difference in the structure between red giants and solar-like stars: the size of the convective zone, the region where all the gas is completely mixed. In the Sun, this convective zone comprises only 2% of the star's mass. But in red giants, the convective zone is huge, encompassing 35 times more mass. The polluting material would thus be 35 times more diluted in a red giant than in a solar-like star. "Although the interpretation of the data is not straightforward, the simplest explanation is that solar-like stars appear metal-rich because of the pollution of their atmospheres," says co-author Artie Hatzes, Director of the Thüringer Landessternwarte Tautenburg (Germany) where some of the data were obtained. When the star was still surrounded by a proto-planetary disc, material enriched in more heavy elements would fall onto the star, thereby polluting its surface. The metal excess produced by this pollution, while visible in the thin atmospheres of solar-like stars, is completely diluted in the extended, massive atmospheres of the giants.

High-Resolution NMR Reveals Secondary Structure and Folding of Amino Acid Transporter from Outer Chloroplast Membrane

PubMed Central

Zook, James D.; Molugu, Trivikram R.; Jacobsen, Neil E.; Lin, Guangxin; Soll, Jürgen; Cherry, Brian R.; Brown, Michael F.; Fromme, Petra

2013-01-01

Solving high-resolution structures for membrane proteins continues to be a daunting challenge in the structural biology community. In this study we report our high-resolution NMR results for a transmembrane protein, outer envelope protein of molar mass 16 kDa (OEP16), an amino acid transporter from the outer membrane of chloroplasts. Three-dimensional, high-resolution NMR experiments on the 13C, 15N, 2H-triply-labeled protein were used to assign protein backbone resonances and to obtain secondary structure information. The results yield over 95% assignment of N, HN, CO, Cα, and Cβ chemical shifts, which is essential for obtaining a high resolution structure from NMR data. Chemical shift analysis from the assignment data reveals experimental evidence for the first time on the location of the secondary structure elements on a per residue basis. In addition T 1Z and T2 relaxation experiments were performed in order to better understand the protein dynamics. Arginine titration experiments yield an insight into the amino acid residues responsible for protein transporter function. The results provide the necessary basis for high-resolution structural determination of this important plant membrane protein. PMID:24205117

Helium stars: Towards an understanding of Wolf-Rayet evolution

NASA Astrophysics Data System (ADS)

McClelland, Liam A. S.; Eldridge, J. J.

2017-11-01

Recent observational modelling of the atmospheres of hydrogen-free Wolf-Rayet stars have indicated that their stellar surfaces are cooler than those predicted by the latest stellar evolution models. We have created a large grid of pure helium star models to investigate the dependence of the surface temperatures on factors such as the rate of mass loss and the amount of clumping in the outer convection zone. Upon comparing our results with Galactic and LMC WR observations, we find that the outer convection zones should be clumped and that the mass-loss rates need to be slightly reduced. We discuss the implications of these findings in terms of the detectability of Type Ibc supernovae progenitors, and in terms of refining the Conti scenario.

Giant planets: Clues on current and past organic chemistry in the outer solar system

NASA Technical Reports Server (NTRS)

Pollack, James B.; Atreya, Sushil K.

1992-01-01

The giant planets of the outer solar system - Jupiter, Saturn, Uranus, and Neptune - were formed in the same flattened disk of gas and dust, the solar nebula, as the terrestrial planets were. Yet, the giant planets differ in some very fundamental ways from the terrestrial planets. Despite enormous differences, the giant planets are relevant to exobiology in general and the origin of life on the Earth in particular. The giant planets are described as they are today. Their basic properties and the chemistry occurring in their atmospheres is discussed. Theories of their origin are explored and aspects of these theories that may have relevance to exobiology and the origin of life on Earth are stressed.

Engaging space: extraterrestrial architecture and the human psyche.

PubMed

Sequin, Angel Marie

2005-01-01

The human fascination with exploring and inhabiting the space that lies beyond Earth's atmosphere continues to grow. Nevertheless, 40 years of experience to date have clearly established that humans in outer space routinely suffer significant psychological impairment arising from their stressful extraterrestrial living conditions. This paper explores those extraterrestrial conditions through the interactions between the extraordinarily harsh environment of outer space, the sensations that humans encounter in space, and the qualities of a habitat that physically interposes itself between the two. The objective of this paper is to develop a habitat that expresses the extraterrestrial condition while supporting the mental health of its inhabitants, so as to augment the success of prolonged extraterrestrial residence and interplanetary travel. c2005 Elsevier Ltd. All rights reserved.

Functional activity of plasmid DNA after entry into the atmosphere of earth investigated by a new biomarker stability assay for ballistic spaceflight experiments.

PubMed

Thiel, Cora S; Tauber, Svantje; Schütte, Andreas; Schmitz, Burkhard; Nuesse, Harald; Moeller, Ralf; Ullrich, Oliver

2014-01-01

Sounding rockets represent an excellent platform for testing the influence of space conditions during the passage of Earth's atmosphere and re-entry on biological, physical and chemical experiments for astrobiological purposes. We designed a robust functionality biomarker assay to analyze the biological effects of suborbital spaceflights prevailing during ballistic rocket flights. During the TEXUS-49 rocket mission in March 2011, artificial plasmid DNA carrying a fluorescent marker (enhanced green fluorescent protein: EGFP) and an antibiotic resistance cassette (kanamycin/neomycin) was attached on different positions of rocket exterior; (i) circular every 90 degree on the outer surface concentrical of the payload, (ii) in the grooves of screw heads located in between the surface application sites, and (iii) on the surface of the bottom side of the payload. Temperature measurements showed two major peaks at 118 and 130 °C during the 780 seconds lasting flight on the inside of the recovery module, while outer gas temperatures of more than 1000 °C were estimated on the sample application locations. Directly after retrieval and return transport of the payload, the plasmid DNA samples were recovered. Subsequent analyses showed that DNA could be recovered from all application sites with a maximum of 53% in the grooves of the screw heads. We could further show that up to 35% of DNA retained its full biological function, i.e., mediating antibiotic resistance in bacteria and fluorescent marker expression in eukaryotic cells. These experiments show that our plasmid DNA biomarker assay is suitable to characterize the environmental conditions affecting DNA during an atmospheric transit and the re-entry and constitute the first report of the stability of DNA during hypervelocity atmospheric transit indicating that sounding rocket flights can be used to model the high-speed atmospheric entry of organics-laden artificial meteorites.

Functional Activity of Plasmid DNA after Entry into the Atmosphere of Earth Investigated by a New Biomarker Stability Assay for Ballistic Spaceflight Experiments

PubMed Central

Thiel, Cora S.; Tauber, Svantje; Schütte, Andreas; Schmitz, Burkhard; Nuesse, Harald; Moeller, Ralf; Ullrich, Oliver

2014-01-01

Sounding rockets represent an excellent platform for testing the influence of space conditions during the passage of Earth's atmosphere and re-entry on biological, physical and chemical experiments for astrobiological purposes. We designed a robust functionality biomarker assay to analyze the biological effects of suborbital spaceflights prevailing during ballistic rocket flights. During the TEXUS-49 rocket mission in March 2011, artificial plasmid DNA carrying a fluorescent marker (enhanced green fluorescent protein: EGFP) and an antibiotic resistance cassette (kanamycin/neomycin) was attached on different positions of rocket exterior; (i) circular every 90 degree on the outer surface concentrical of the payload, (ii) in the grooves of screw heads located in between the surface application sites, and (iii) on the surface of the bottom side of the payload. Temperature measurements showed two major peaks at 118 and 130°C during the 780 seconds lasting flight on the inside of the recovery module, while outer gas temperatures of more than 1000°C were estimated on the sample application locations. Directly after retrieval and return transport of the payload, the plasmid DNA samples were recovered. Subsequent analyses showed that DNA could be recovered from all application sites with a maximum of 53% in the grooves of the screw heads. We could further show that up to 35% of DNA retained its full biological function, i.e., mediating antibiotic resistance in bacteria and fluorescent marker expression in eukariotic cells. These experiments show that our plasmid DNA biomarker assay is suitable to characterize the environmental conditions affecting DNA during an atmospheric transit and the re-entry and constitute the first report of the stability of DNA during hypervelocity atmospheric transit indicating that sounding rocket flights can be used to model the high-speed atmospheric entry of organics-laden artificial meteorites. PMID:25426925

Vigorous atmospheric motion in the red supergiant star Antares.

PubMed

Ohnaka, K; Weigelt, G; Hofmann, K-H

2017-08-16

Red supergiant stars represent a late stage of the evolution of stars more massive than about nine solar masses, in which they develop complex, multi-component atmospheres. Bright spots have been detected in the atmosphere of red supergiants using interferometric imaging. Above the photosphere of a red supergiant, the molecular outer atmosphere extends up to about two stellar radii. Furthermore, the hot chromosphere (5,000 to 8,000 kelvin) and cool gas (less than 3,500 kelvin) of a red supergiant coexist at about three stellar radii. The dynamics of such complex atmospheres has been probed by ultraviolet and optical spectroscopy. The most direct approach, however, is to measure the velocity of gas at each position over the image of stars as in observations of the Sun. Here we report the mapping of the velocity field over the surface and atmosphere of the nearby red supergiant Antares. The two-dimensional velocity field map obtained from our near-infrared spectro-interferometric imaging reveals vigorous upwelling and downdrafting motions of several huge gas clumps at velocities ranging from about -20 to +20 kilometres per second in the atmosphere, which extends out to about 1.7 stellar radii. Convection alone cannot explain the observed turbulent motions and atmospheric extension, suggesting that an unidentified process is operating in the extended atmosphere.

History of Hubble Space Telescope (HST)

NASA Image and Video Library

1980-01-01

This illustration shows the Hubble Space Telescope's (HST's) major configuration elements. The spacecraft has three interacting systems: The Support System Module (SSM), an outer structure that houses the other systems and provides services such as power, communication, and control; The Optical Telescope Assembly (OTA), which collects and concentrates the incoming light in the focal plane for use by the Scientific Instruments (SI); and five SIs. The SI Control and Data Handling (CDH) unit controls the five SI's, four that are housed in an aft section focal plane structure and one that is placed along the circumference of the spacecraft. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST detects objects 25 times fainter than the dimmest objects seen from Earth and provides astronomers with an observable universe 250 times larger than visible from ground-based telescopes, perhaps as far away as 14 billion light-years. The HST views galaxies, stars, planets, comets, possibly other solar systems, and even unusual phenomena such as quasars, with 10 times the clarity of ground-based telescopes. The HST was deployed from the Space Shuttle Discovery (STS-31 mission) into Earth orbit in April 1990. The Marshall Space Flight Center had responsibility for design, development, and construction of the HST. The Perkin-Elmer Corporation, in Danbury, Cornecticut, developed the optical system and guidance sensors. The Lockheed Missile and Space Company of Sunnyvale, California produced the protective outer shroud and spacecraft systems, and assembled and tested the finished telescope.

SEMI-EMPIRICAL MODELING OF THE PHOTOSPHERE, CHROMOPSHERE, TRANSITION REGION, AND CORONA OF THE M-DWARF HOST STAR GJ 832

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

Fontenla, J. M.; Linsky, Jeffrey L.; Witbrod, Jesse

Stellar radiation from X-rays to the visible provides the energy that controls the photochemistry and mass loss from exoplanet atmospheres. The important extreme ultraviolet (EUV) region (10–91.2 nm) is inaccessible and should be computed from a reliable stellar model. It is essential to understand the formation regions and physical processes responsible for the various stellar emission features to predict how the spectral energy distribution varies with age and activity levels. We compute a state-of-the-art semi-empirical atmospheric model and the emergent high-resolution synthetic spectrum of the moderately active M2 V star GJ 832 as the first of a series of modelsmore » for stars with different activity levels. We construct a one-dimensional simple model for the physical structure of the star’s chromosphere, chromosphere-corona transition region, and corona using non-LTE radiative transfer techniques and many molecular lines. The synthesized spectrum for this model fits the continuum and lines across the UV-to-optical spectrum. Particular emphasis is given to the emission lines at wavelengths that are shorter than 300 nm observed with the Hubble Space Telescope , which have important effects on the photochemistry of the exoplanet atmospheres. The FUV line ratios indicate that the transition region of GJ 832 is more biased to hotter material than that of the quiet Sun. The excellent agreement of our computed EUV luminosity with that obtained by two other techniques indicates that our model predicts reliable EUV emission from GJ 832. We find that the unobserved EUV flux of GJ 832, which heats the outer atmospheres of exoplanets and drives their mass loss, is comparable to the active Sun.« less

Insight into mitochondrial structure and function from electron tomography.

PubMed

Frey, T G; Renken, C W; Perkins, G A

2002-09-10

In recent years, electron tomography has provided detailed three-dimensional models of mitochondria that have redefined our concept of mitochondrial structure. The models reveal an inner membrane consisting of two components, the inner boundary membrane (IBM) closely apposed to the outer membrane and the cristae membrane that projects into the matrix compartment. These two components are connected by tubular structures of relatively uniform size called crista junctions. The distribution of crista junction sizes and shapes is predicted by a thermodynamic model based upon the energy of membrane bending, but proteins likely also play a role in determining the conformation of the inner membrane. Results of structural studies of mitochondria during apoptosis demonstrate that cytochrome c is released without detectable disruption of the outer membrane or extensive swelling of the mitochondrial matrix, suggesting the formation of an outer membrane pore large enough to allow passage of holo-cytochrome c. The possible compartmentation of inner membrane function between the IBM and the cristae membrane is also discussed.

Electrochemical cell design

DOEpatents

Arntzen, John D.

1978-01-01

An electrochemical cell includes two outer electrodes and a central electrode of opposite polarity, all nested within a housing having two symmetrical halves which together form an offset configuration. The outer electrodes are nested within raised portions within the side walls of each housing half while the central electrode sealingly engages the perimetric margins of the side-wall internal surfaces. Suitable interelectrode separators and electrical insulating material electrically isolate the central electrode from the housing and the outer electrodes. The outer electrodes are electrically connected to the internal surfaces of the cell housing to provide current collection. The nested structure minimizes void volume that would otherwise be filled with gas or heavy electrolyte and also provides perimetric edge surfaces for sealing and supporting at the outer margins of frangible interelectrode separator layers.

Structured copolymers and their use as absorbents, gels and carriers of metal ions

DOEpatents

Hedstrand, David M.; Helmer, Bradley J.; Tomalia, Donald A.

1996-01-01

Dense star polymers or dendrimers having a highly branched interior structure capable of associating or chelating with metal ions are modified by capping with a hydrophobic group capable of providing a hydrophobic outer shell. The modified dendrimers are useful for dispersing metal ions in a non-aqueous polymer matrix. Also dense star polymers or dendrimers having a highly branched hydrophilic interior structure are modified by capping with a hydrophobic group capable of providing a hydrophobic outer shell, which modified polymers are useful as gels and surfactants.

Structured copolymers and their use as absorbents, gels and carriers of metal ions

DOEpatents

Hedstrand, D.M.; Helmer, B.J.; Tomalia, D.A.

1996-10-01

Dense star polymers or dendrimers having a highly branched interior structure capable of associating or chelating with metal ions are modified by capping with a hydrophobic group capable of providing a hydrophobic outer shell. The modified dendrimers are useful for dispersing metal ions in a non-aqueous polymer matrix. Also dense star polymers or dendrimers having a highly branched hydrophilic interior structure are modified by capping with a hydrophobic group capable of providing a hydrophobic outer shell, which modified polymers are useful as gels and surfactants.

THE STRUCTURE AND CONCENTRATION OF SOLIDS IN PHOTORECEPTOR CELLS STUDIED BY REFRACTOMETRY AND INTERFERENCE MICROSCOPY

PubMed Central

Sidman, Richard L.

1957-01-01

Fragments of freshly obtained retinas of several vertebrate species were studied by refractometry, with reference to the structure of the rods and cones. The findings allowed a reassessment of previous descriptions based mainly on fixed material. The refractometric method was used also to measure the refractice indices and to calculate the concentrations of solids and water in the various cell segments. The main quantitative data were confirmed by interference microscopy. When examined by the method of refractometry the outer segments of freshly prepared retinal rods appear homogeneous. Within a few minutes a single eccentric longitudinal fiber appears, and transverse striations may develop. These changes are attributed to imbibition of water and swelling in structures normally too small for detection by light microscopy. The central "core" of outer segments and the chromophobic disc between outer and inner segments appear to be artifacts resulting from shrinkage during dehydration. The fresh outer segments of cones, and the inner segments of rods and cones also are described and illustrated. The volumes, refractive indices, concentrations of solids, and wet and dry weights of various segments of the photoreceptor cells were tabulated. Rod outer segments of the different species vary more than 100-fold in volume and mass but all have concentrations of solids of 40 to 43 per cent. Cone outer segments contain only about 30 per cent solids. The myoids, paraboloids, and ellipsoids of the inner segments likewise have characteristic refractive indices and concentrations of solids. Some of the limitations and particular virtues of refractometry as a method for quantitative analysis of living cells are discussed in comparison with more conventional biochemical techniques. Also the shapes and refractive indices of the various segments of photoreceptor cells are considered in relation to the absorption and transmission of light. The Stiles-Crawford effect can be accounted for on the basis of the structure of cone cells. PMID:13416308

Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass

NASA Technical Reports Server (NTRS)

Kopparapu, Ravi Kumar; Ramirez, Ramses M.; Kotte, James Schottel; Kasting, James F.; Domagal-Goldman, Shawn; Eymet, Vincent

2014-01-01

The ongoing discoveries of extra-solar planets are unveiling a wide range of terrestrial mass (size) planets around their host stars. In this Letter, we present estimates of habitable zones (HZs) around stars with stellar effective temperatures in the range 2600 K-7200 K, for planetary masses between 0.1M and 5M. Assuming H2O-(inner HZ) and CO2-(outer HZ) dominated atmospheres, and scaling the background N2 atmospheric pressure with the radius of the planet, our results indicate that larger planets have wider HZs than do smaller ones. Specifically, with the assumption that smaller planets will have less dense atmospheres, the inner edge of the HZ (runaway greenhouse limit) moves outward (approx.10% lower than Earth flux) for low mass planets due to larger greenhouse effect arising from the increased H2O column depth. For larger planets, the H2O column depth is smaller, and higher temperatures are needed before water vapor completely dominates the outgoing long-wave radiation. Hence the inner edge moves inward (approx.7% higher than Earth's flux). The outer HZ changes little due to the competing effects of the greenhouse effect and an increase in albedo. New, three-dimensional climate model results from other groups are also summarized, and we argue that further, independent studies are needed to verify their predictions. Combined with our previous work, the results presented here provide refined estimates of HZs around main-sequence stars and provide a step toward a more comprehensive analysis of HZs.

Laboratory studies of low temperature rate coefficients: The atmospheric chemistry of the outer planets

NASA Technical Reports Server (NTRS)

Leone, Stephen R.

1993-01-01

The objectives are to measure laboratory rate coefficients for key reactions of hydrocarbon molecules and radicals at low temperatures, which are relevant to the atmospheric photochemistry of Saturn, Jupiter, and Titan. Upcoming NASA planetary missions, such as Cassini, will probe the atmosphere of Titan in more detail, offering an excellent opportunity to test kinetic models and to establish fiducial standards for using kinetic models to interpret various parameters of the outer planets. Accurate low temperature kinetic data, which are presently lacking, may require crucial revisions to the rates of formation and destruction and are of utmost importance to the success of these efforts. In this program, several key reactions of ethynyl radicals (C2H) with acetylene (C2H2), methane (CH4), and oxygen (O2), down to temperatures of 170 K were successfully investigated. The experimental apparatus developed in our laboratory for measuring reaction kinetics at low temperatures consists of a laser photolysis/infrared probe laser setup. The rate measurements are carried out as a function of (low) temperature with a transverse flow cell designed specifically for these studies. A 193 nm argon fluoride pulsed excimer laser is used to photolyze a suitable precursor molecule, such as acetylene to produce C2H, and a high resolution, tunable infrared F-center laser (2.3-3.35 mu m) probes the transient concentrations of the radical species directly in absorption to extract the kinetic rate coefficients.

Effects of long-term elevated CO2 treatment on the inner and outer bark chemistry of sweetgum (Liquidambar styraciflua L.) trees

Treesearch

Thomas L. Eberhardt; Nicole Labbé; Chi-Leung So; Keonhee Kim; Karen G. Reed; Daniel J. Leduc; Jeffrey M. Warren

2015-01-01

Changes in plant tissue chemistry due to increasing atmospheric carbon dioxide (CO2) concentrations have direct implications for tissue resistance to abiotic and biotic stress while living, and soil nutrient cycling when senesced as litter. Although the effects of elevatedCO2 concentrations on tree foliar chemistry are well...

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.

Table and charts of equilibrium normal-shock properties for hydrogen-helium mixtures with velocities to 70 km/sec. Volume 1: 0.95 H2-0.05 He (by volume)

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1976-01-01

Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves into hydrogen-helium mixtures representative of postulated outer planet atmospheres. These results are presented in four volumes and the volmetric compositions of the mixtures are 0.95H2-0.05He in Volume 1, 0.90H2-0.10He in Volume 2, 0.85H2-0.15He in Volume 3, and 0.75H2-0.25He in Volume 4. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular-weight ratio, isentropic exponent, velocity, and species mole fractions. Incident (moving) shock velocities are varied from 4 to 70 km/sec for a range of initial pressure of 5 N/sq m to 100 kN/sq m. Results are applicable to shock-tube flows and for determining flow conditions behind the normal portion of the bow shock about a blunt body at high velocities in postulated outer planet atmospheres. The document is a revised version of the original edition of NASA SP-3085 published in 1974.

Tryptophan 375 stabilizes the outer-domain core of gp120 for HIV vaccine immunogen design.

PubMed

Hu, Duoyi; Bowder, Dane; Wei, Wenzhong; Thompson, Jesse; Wilson, Mark A; Xiang, Shi-Hua

2017-05-25

The outer-domain core of gp120 may serve as a better HIV vaccine immunogen than the full-length gp120 because of its greater stability and immunogenicity. In our previous report, we introduced two disulfide bonds to the outer-domain core of gp120 to fix its conformation into a CD4-bound state, which resulted in a significant increase in its immunogenicity when compared to the wild-type outer-domain core. In this report, to further improve the immunogenicity of the outer-domain core based immunogen, we have introduced a Tryptophan residue at gp120 amino acid sequence position 375 (375S/W). Our data from immunized guinea pigs indeed shows a striking increase in the immune response due to this stabilized core outer-domain. Therefore, we conclude that the addition of 375W to the outer-domain core of gp120 further stabilizes the structure of immunogen and increases the immunogenicity. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Swirling structure for mixing two concentric fluid flows at nozzle outlet

DOEpatents

Mensink, D.L.

1993-07-20

A nozzle device is described for causing two fluids to mix together. In particular, a spray nozzle comprises two hollow, concentric housings, an inner housing and an outer housing. The inner housing has a channel formed therethrough for a first fluid. Its outer surface cooperates with the interior surface of the outer housing to define the second channel for a second fluid. The outer surface of the inner housing and the inner surface of the outer housing each carry a plurality of vanes that interleave but do not touch, each vane of one housing being between two vanes of the other housing. The vanes are curved and the inner surface of the outer housing and the outer surface of the inner housing converge to narrow the second channel. The shape of second channel results in a swirling, accelerating second fluid that will impact the first fluid just past the end of the nozzle where mixing will take place.

Gas turbine row #1 steam cooled vane

DOEpatents

Cunha, Frank J.

2000-01-01

A design for a vane segment having a closed-loop steam cooling system is provided. The vane segment comprises an outer shroud, an inner shroud and an airfoil, each component having a target surface on the inside surface of its walls. A plurality of rectangular waffle structures are provided on the target surface to enhance heat transfer between each component and cooling steam. Channel systems are provided in the shrouds to improve the flow of steam through the shrouds. Insert legs located in cavities in the airfoil are also provided. Each insert leg comprises outer channels located on a perimeter of the leg, each outer channel having an outer wall and impingement holes on the outer wall for producing impingement jets of cooling steam to contact the airfoil's target surface. Each insert leg further comprises a plurality of substantially rectangular-shaped ribs located on the outer wall and a plurality of openings located between outer channels of the leg to minimize cross flow degradation.

Planning Assembly Of Large Truss Structures In Outer Space

NASA Technical Reports Server (NTRS)

De Mello, Luiz S. Homem; Desai, Rajiv S.

1992-01-01

Report dicusses developmental algorithm used in systematic planning of sequences of operations in which large truss structures assembled in outer space. Assembly sequence represented by directed graph called "assembly graph", in which each arc represents joining of two parts or subassemblies. Algorithm generates assembly graph, working backward from state of complete assembly to initial state, in which all parts disassembled. Working backward more efficient than working forward because it avoids intermediate dead ends.

Integrated gas turbine engine-nacelle

NASA Technical Reports Server (NTRS)

Adamson, A. P.; Sargisson, D. F.; Stotler, C. L., Jr. (Inventor)

1979-01-01

A nacelle for use with a gas turbine engine is provided with an integral webbed structure resembling a spoked wheel for rigidly interconnecting the nacelle and engine. The nacelle is entirely supported in its spacial relationship with the engine by means of the webbed structure. The inner surface of the nacelle defines the outer limits of the engine motive fluid flow annulus, while the outer surface of the nacelle defines a streamlined envelope for the engine.

Ultrastructural studies on the boundary tissue of the seminiferous tubules of different mammals.

PubMed

Cieciura, L; Jaszczuk-Jarosz, B; Pietrzkowska, K

1988-01-01

The aims of our studies were to compare the ultrastructure of the boundary tissue of seminiferous tubules of various mammals (rat, mouse, hamster, guinea pig, rabbit, ram, bull and man). Visual analysis of electron micrographs revealed the similarity of structure of all layers at investigated animals. The boundary tissue consists of 4 layers: 1) amorphous inner lamina, 2) cellular inner lamina, 3) amorphous outer lamina, 4) cellular outer lamina. The outer lamina of boundary tissue of rat, mouse and hamster revealed in histochemical reactions meshes resembling honey-combs. The wall of seminiferous canalicules of bull and ram consists of more bigger and different structure than one at the other laboratory animals. The most different structure of boundary tissue in man was observed. The capillary vessels penetrate in the myofibroblastic layer, when comparted to that found in other mammals on the surface of the wall.

Cytologic appearance of retinal cells included in a fine-needle aspirate of a meningioma around the optic nerve of a dog.

PubMed

Tvedten, Harold; Hillström, Anna

2013-06-01

A 6-year-old Wirehair Dachshund had a meningioma around the optic nerve that caused exophthalmos. A benign mesenchymal tumor was suspected based on the cytologic pattern of a fine-needle aspirate, and a meningioma was diagnosed by histopathologic examination. In addition to the meningioma cells, the cytologic smears included groups of cells from apparently 4 layers of normal retina. In particular, uniform rod-shaped structures in the cytologic sample could suggest rod-shaped bacteria, but these structures were identified as cylindrical outer segments of photoreceptor rod cells. Other retinal structures recognized included pigmented epithelial layer cells with their uniquely formed pigment granules, the characteristic bi-lobed, cleaved nuclei from the outer nuclear layer, and nerve tissue likely from the outer plexiform layer of the retina. © 2013 American Society for Veterinary Clinical Pathology.

ACUTE ZONAL OCCULT OUTER RETINOPATHY: Structural and Functional Analysis Across the Transition Zone Between Healthy and Diseased Retina.

PubMed

Duncker, Tobias; Lee, Winston; Jiang, Fan; Ramachandran, Rithambara; Hood, Donald C; Tsang, Stephen H; Sparrow, Janet R; Greenstein, Vivienne C

2018-01-01

To assess structure and function across the transition zone (TZ) between relatively healthy and diseased retina in acute zonal occult outer retinopathy. Six patients (6 eyes; age 22-71 years) with acute zonal occult outer retinopathy were studied. Spectral-domain optical coherence tomography, fundus autofluorescence, near-infrared reflectance, color fundus photography, and fundus perimetry were performed and images were registered to each other. The retinal layers of the spectral-domain optical coherence tomography scans were segmented and the thicknesses of two outer retinal layers, that is, the total receptor and outer segment plus layers, and the retinal nerve fiber layer were measured. All eyes showed a TZ on multimodal imaging. On spectral-domain optical coherence tomography, the TZ was in the nasal retina at varying distances from the fovea. For all eyes, it was associated with loss of the ellipsoid zone band, significant thinning of the two outer retinal layers, and in three eyes with thickening of the retinal nerve fiber layer. On fundus autofluorescence, all eyes had a clearly demarcated peripapillary area of abnormal fundus autofluorescence delimited by a border of high autofluorescence; the latter was associated with loss of the ellipsoid zone band and with a change from relatively normal to markedly decreased or nonrecordable visual sensitivity on fundus perimetry. The results of multimodal imaging clarified the TZ in acute zonal occult outer retinopathy. The TZ was outlined by a distinct high autofluorescence border that correlated with loss of the ellipsoid zone band on spectral-domain optical coherence tomography. However, in fundus areas that seemed healthy on fundus autofluorescence, thinning of the outer retinal layers and thickening of the retinal nerve fiber layer were observed near the TZ. The TZ was also characterized by a decrease in visual sensitivity.

LppX is a lipoprotein required for the translocation of phthiocerol dimycocerosates to the surface of Mycobacterium tuberculosis

PubMed Central

Sulzenbacher, Gerlind; Canaan, Stéphane; Bordat, Yann; Neyrolles, Olivier; Stadthagen, Gustavo; Roig-Zamboni, Véronique; Rauzier, Jean; Maurin, Damien; Laval, Françoise; Daffé, Mamadou; Cambillau, Christian; Gicquel, Brigitte; Bourne, Yves; Jackson, Mary

2006-01-01

Cell envelope lipids play an important role in the pathogenicity of mycobacteria, but the mechanisms by which they are transported to the outer membrane of these prokaryotes are largely unknown. Here, we provide evidence that LppX is a lipoprotein required for the translocation of complex lipids, the phthiocerol dimycocerosates (DIM), to the outer membrane of Mycobacterium tuberculosis. Abolition of DIM transport following disruption of the lppX gene is accompanied by an important attenuation of the virulence of the tubercle bacillus. The crystal structure of LppX unveils an U-shaped β-half-barrel dominated by a large hydrophobic cavity suitable to accommodate a single DIM molecule. LppX shares a similar fold with the periplasmic molecular chaperone LolA and the outer membrane lipoprotein LolB, which are involved in the localization of lipoproteins to the outer membrane of Gram-negative bacteria. Based on the structure and although an indirect participation of LppX in DIM transport cannot yet be ruled out, we propose LppX to be the first characterized member of a family of structurally related lipoproteins that carry lipophilic molecules across the mycobacterial cell envelope. PMID:16541102

Outer Membrane Targeting of Passenger Proteins by the Vacuolating Cytotoxin Autotransporter of Helicobacter pylori

PubMed Central

Fischer, Wolfgang; Buhrdorf, Renate; Gerland, Elke; Haas, Rainer

2001-01-01

Helicobacter pylori produces a number of proteins associated with the outer membrane, including adhesins and the vacuolating cytotoxin. These proteins are supposed to integrate into the outer membrane by β-barrel structures, characteristic of the family of autotransporter proteins. By using the SOMPES (shuttle vector-based outer membrane protein expression) system for outer membrane protein production, we were able to functionally express in H. pylori the cholera toxin B subunit genetically fused to the C-terminal VacA domain. We demonstrate that the fusion protein is translocated to the H. pylori outer membrane and that the CtxB domain is exposed on the H. pylori surface. Thus, we provide the first experimental evidence that the C-terminal β-domain of VacA can transport a foreign passenger protein to the H. pylori surface and hence acts as a functional autotransporter. PMID:11598049

The Role of the Dynamic Plasmapause on Outer Radiation Belt Electron Flux Enhancement and Three-Belt Structure Formation

NASA Astrophysics Data System (ADS)

Bruff, M.; Jaynes, A. N.; Zhao, H.; Malaspina, D.

2017-12-01

The plasmasphere is a highly dynamic toroidal region of cold, dense plasma around Earth. Plasma waves exist both inside and outside this region and can contribute to the loss and acceleration of high energy outer radiation belt electrons. Early observational studies found an apparent correlation on long time scales between the observed inner edge of the outer radiation belt and the simulated innermost plasmapause location. More recent work using high resolution Van Allen Probe satellite data has found a more complex relationship. The aim of this project was to provide a systematic study of the location and dynamics of the plasmapause compared to the MeV electrons in the outer radiation belt. We used spin-averaged electron flux data from the Relativistic Electron Proton Telescope (REPT) and density data derived from the EFW instrument on the Van Allen Probe satellites. We analyzed these data to determine the standoff distance of the location of peak electron flux of the outer belt MeV electrons from the plasmapause. We found that the location of peak flux was consistently outside but within ΔL=2.5 from the innermost location of the plasmapause at enhancement times, with an average standoff distance ΔL=1.0 +/- 0.5. This is consistent with the current model of chorus enhancement and previous observations of chorus activity. Finally, we identified "three-belt" structure events where a second outer belt formed and found a repeated pattern of plasmapause dynamics associated with specific changes in electron flux required to generate and sustain these structures. This study is significant to improving our understanding of how the plasmasphere under differing conditions can both shield Earth from or worsen the impacts of geomagnetic activity.

Stellar populations, stellar masses and the formation of galaxy bulges and discs at z < 3 in CANDELS

NASA Astrophysics Data System (ADS)

Margalef-Bentabol, Berta; Conselice, Christopher J.; Mortlock, Alice; Hartley, Will; Duncan, Kenneth; Kennedy, Rebecca; Kocevski, Dale D.; Hasinger, Guenther

2018-02-01

We present a multicomponent structural analysis of the internal structure of 1074 high-redshift massive galaxies at 1 < z < 3 from the CANDELS HST Survey. In particular, we examine galaxies best fitted by two structural components, and thus likely forming discs and bulges. We examine the stellar mass, star formation rates (SFRs) and colours of both the inner 'bulge' and outer 'disc' components for these systems using Spectral Energy Distribution (SED) information from the resolved ACS+WFC3 HST imaging. We find that the majority of both inner and outer components lie in the star-forming region of UVJ space (68 and 90 per cent, respectively). However, the inner portions, or the likely forming bulges, are dominated by dusty star formation. Furthermore, we show that the outer components of these systems have a higher SFR than their inner regions, and the ratio of SFR between 'disc' and 'bulge' increases at lower redshifts. Despite the higher SFR of the outer component, the stellar mass ratio of inner to outer component remains constant through this epoch. This suggests that there is mass transfer from the outer to inner components for typical two-component-forming systems, thus building bulges from discs. Finally, using Chandra data we find that the presence of an active galactic nucleus is more common in both one-component spheroid-like galaxies and two-component systems (13 ± 3 and 11 ± 2 per cent) than in one-component disc-like galaxies (3 ± 1 per cent), demonstrating that the formation of a central inner component likely triggers the formation of central massive black holes in these galaxies.

Cosmic dust in the atmosphere and in the interplanetary space at 1 AU today and in the early solar system

NASA Technical Reports Server (NTRS)

Fechtig, H.

1973-01-01

A description of techniques used in recent experiments to detect and analyze cosmic dust and micrometeorites is given and the results both from the study of lunar crater statistics and from in situ measurements are reviewed. The results from lunar crater statistics show an agreement with the results obtained from in situ measurements in interplanetary space and derived from zodiacal light measurements. The near earth results show an enhancement in the flux numbers. This can be caused either by secondary lunar debris or by disintegration of low density fireballs in the outer atmosphere.

ARL2BP, a protein linked to Retinitis Pigmentosa, is needed for normal photoreceptor cilia doublets and outer segment structure.

PubMed

Moye, Abigail R; Singh, Ratnesh; Kimler, Victoria A; Dilan, Tanya L; Munezero, Daniella; Saravanan, Thamaraiselvi; Goldberg, Andrew F X; Ramamurthy, Visvanathan

2018-05-02

The outer segment (OS) of photoreceptor cells is an elaboration of a primary cilium with organized stacks of membranous discs that contain the proteins needed for phototransduction and vision. Though cilia formation and function has been well characterized, little is known about the role of cilia in the development of photoreceptor OS. Nevertheless, progress has been made by studying mutations in ciliary proteins which often result in malformed outer segments and lead to blinding diseases. To investigate how ciliary proteins contribute to outer segment formation, we generated a knockout mouse model for ARL2BP, a ciliary protein linked to Retinitis Pigmentosa. The knockout mice display an early and progressive reduction in visual response. Prior to photoreceptor degeneration we observed disorganization of the photoreceptor OS, with vertically aligned discs and shortened axonemes. Interestingly, ciliary doublet microtubule structure was also impaired, displaying open B-tubule doublets, paired with loss of singlet microtubules. Based on results from this study, we conclude that ARL2BP is necessary for photoreceptor cilia doublet formation and axoneme elongation, which is required for outer segment morphogenesis and vision.

OUTER RADIATION BELT AND AURORAS

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

Gorchakov, E.V.

1961-01-01

Data obtained from Sputnik IH were used to determine the high-latitude boundary of the outer radiation belt and to interpret the nature of auroras. At the heights at which the auroras were observed, the outer boundary of the belt (69 deg north geomagnetic latitude) practically coincides with the auroral zone maximum (70 deg north geomagnetic latitude), while the maximum intensity of the outer belt near the earth lies at about 55 deg north geomagnetic latitude, i.e., at latitudes 15 deg below the auroral maximum. Consequently, auroras near the zone of maximum cannot be caused by the penetration into the atmospheremore » of electrons from the outer belt with energies on the order of 0.1 Mev (the mean energy of electrons in the outer belt). Other investigators have reported the detection of lowenergy streams at 55,000 to 75,000 km from the center of the earth in the equatorial plane. Moving toward the surface of the earth along the force lines of the magnetic field, electron streams of this type will reach the earth precisely in the region of the auroral zone maximum. It is considered possible that the electron streams are trapped at these distances from the earth and are at least partially responsible for auroras in the region of maximum. The existence of two maxima in the latitudinal distribution of auroral frequency, which attests to differert mechanisms of aurora formation, favors this hypothesis. In the region of the basic auroral maximum (70 deg north geomagnetic latitude) the auroras are the result of the invasion of belt particles, while in the region of the additional maximum (about 80 deg north geomagnetic latitude) they are caused by the direct penetration of corpuscular streams into the atmosphere. (OTS)« less

Radial diffusion comparing a THEMIS statistical model with geosynchronous measurements as the outer boundary

NASA Astrophysics Data System (ADS)

Li, Z.; Hudson, M. K.; Chen, Y.

2013-12-01

The outer boundary energetic electron flux is used as a driver in radial diffusion calculations, and its precise determination is critical to the solution. A new model was proposed recently based on THEMIS measurements to express the boundary flux as three fit functions of solar wind parameters in a response window, that depend on energy and which solar parameter is used: speed, density, or both (Shin and Lee, 2013). The Dartmouth radial diffusion model has been run using LANL geosynchronous satellite measurements as the outer boundary for a one-month interval in July to August 2004 and the calculated phase space density (PSD) is compared with GPS measurements at the GPS orbit (L=4.16), at magnetic equatorial plane crossings, as a test of the model. We also used the outer boundary generated from the Shin and Lee model and examined this boundary condition by computing the error relative to the simulation using a LANL geosynchronous spacecraft data-driven outer boundary. The calculation shows that there is overestimation and underestimation at different times, however the new boundary condition can be used to drive the radial diffusion model generally, producing the phase space density increase and dropout during a storm with a relatively small error. Having this new method based on a solar wind parametrized data set, we can run the radial diffusion model for storms when particle measurements are not available at the outer boundary. We chose the Whole Heliosphere Interval (WHI) as an example and compared the result with MHD/test-particle simulations (Hudson et al., 2012), obtaining much better agreement with PSD based on GPS measurements at L=4.16 using the diffusion model, which incorporates atmospheric losses.

The periplasmic domain of Escherichia coli outer membrane protein A can undergo a localized temperature dependent structural transition.

PubMed

Ishida, Hiroaki; Garcia-Herrero, Alicia; Vogel, Hans J

2014-12-01

Gram-negative bacteria such as Escherichia coli are surrounded by two membranes with a thin peptidoglycan (PG)-layer located in between them in the periplasmic space. The outer membrane protein A (OmpA) is a 325-residue protein and it is the major protein component of the outer membrane of E. coli. Previous structure determinations have focused on the N-terminal fragment (residues 1-171) of OmpA, which forms an eight stranded transmembrane β-barrel in the outer membrane. Consequently it was suggested that OmpA is composed of two independently folded domains in which the N-terminal β-barrel traverses the outer membrane and the C-terminal domain (residues 180-325) adopts a folded structure in the periplasmic space. However, some reports have proposed that full-length OmpA can instead refold in a temperature dependent manner into a single domain forming a larger transmembrane pore. Here, we have determined the NMR solution structure of the C-terminal periplasmic domain of E. coli OmpA (OmpA(180-325)). Our structure reveals that the C-terminal domain folds independently into a stable globular structure that is homologous to the previously reported PG-associated domain of Neisseria meningitides RmpM. Our results lend credence to the two domain structure model and a PG-binding function for OmpA, and we could indeed localize the PG-binding site on the protein through NMR chemical shift perturbation experiments. On the other hand, we found no evidence for binding of OmpA(180-325) with the TonB protein. In addition, we have also expressed and purified full-length OmpA (OmpA(1-325)) to study the structure of the full-length protein in micelles and nanodiscs by NMR spectroscopy. In both membrane mimetic environments, the recombinant OmpA maintains its two domain structure that is connected through a flexible linker. A series of temperature-dependent HSQC experiments and relaxation dispersion NMR experiments detected structural destabilization in the bulge region of the periplasmic domain of OmpA above physiological temperatures, which may induce dimerization and play a role in triggering the previously reported larger pore formation. Copyright © 2014 Elsevier B.V. All rights reserved.

Estimation of Mass-Loss Rate for M Giants from UV Emission Line Profiles

NASA Technical Reports Server (NTRS)

Carpenter, Kenneth G.; Robinson, R. D.; Fisher, Richard R. (Technical Monitor)

2001-01-01

The photon-scattering winds of M giants produce absorption features in the strong chromospheric emission lines. These provide us with an opportunity to assess important parameters of the wind, including flow and turbulent velocities, the optical depth of the wind above the region of photon creation, and the star's mass-loss rate. We have used the Lamers et al. (1987) Sobolev with Exact Integration (SET) radiative transfer code, along with simple models of the outer atmospheric structure and wind, to determine the wind characteristics of two M-giant stars, gamma Cru (M3.4) and mu Gem (M3IIIab). The SET code has the advantage of being computationally fast and allows a great number of possible wind models to be examined. The analysis procedure involves specifying wind parameters and then using the program to calculate line profiles for the Mg II (UV1) lines and a range of unblended Fe II lines. These lines have a wide range of wind opacities and therefore probe different heights in the atmosphere. The assumed wind properties are iterated until the predicted profiles match the observations over as many lines as possible. We present estimates of the wind parameters for these stars and offer a comparison to wind properties previously-derived for low-gravity K stars using the same technique.

Ion Traps at the Sun: Implications for Elemental Fractionation

NASA Astrophysics Data System (ADS)

Fleishman, Gregory D.; Musset, Sophie; Bommier, Véronique; Glesener, Lindsay

2018-04-01

Why the tenuous solar outer atmosphere, or corona, is much hotter than the underlying layers remains one of the greatest challenges for solar modeling. Detailed diagnostics of the coronal thermal structure come from extreme ultraviolet (EUV) emission. The EUV emission is produced by heavy ions in various ionization states and depends on the amount of these ions and on plasma temperature and density. Any nonuniformity of the elemental distribution in space or variability in time affects thermal diagnostics of the corona. Here we theoretically predict ionized chemical element concentrations in some areas of the solar atmosphere, where the electric current is directed upward. We then detect these areas observationally, by comparing the electric current density with the EUV brightness in an active region. We found a significant excess in EUV brightness in the areas with positive current density rather than negative. Therefore, we report the observational discovery of substantial concentrations of heavy ions in current-carrying magnetic flux tubes, which might have important implications for the elemental fractionation in the solar corona known as the first ionization potential effect. We call such areas of heavy ion concentration the “ion traps.” These traps hold enhanced ion levels until they are disrupted by a flare, whether large or small.

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

Xia, C.; Keppens, R.

Solar prominences are long-lived cool and dense plasma curtains in the hot and rarefied outer solar atmosphere or corona. The physical mechanism responsible for their formation and especially for their internal plasma circulation has been uncertain for decades. The observed ubiquitous downflows in quiescent prominences are difficult to interpret because plasma with high conductivity seems to move across horizontal magnetic field lines. Here we present three-dimensional numerical simulations of prominence formation and evolution in an elongated magnetic flux rope as a result of in situ plasma condensations fueled by continuous plasma evaporation from the solar chromosphere. The prominence is bornmore » and maintained in a fragmented, highly dynamic state with continuous reappearance of multiple blobs and thread structures that move mainly downward, dragging along mass-loaded field lines. The circulation of prominence plasma is characterized by the dynamic balance between the drainage of prominence plasma back to the chromosphere and the formation of prominence plasma via continuous condensation. Plasma evaporates from the chromosphere, condenses into the prominence in the corona, and drains back to the chromosphere, establishing a stable chromosphere–corona plasma cycle. Synthetic images of the modeled prominence with the Solar Dynamics Observatory Atmospheric Imaging Assembly closely resemble actual observations, with many dynamical threads underlying an elliptical coronal cavity.« less

Inner and Outer Coordination Shells of Mg(2+) in CorA Selectivity Filter from Molecular Dynamics Simulations.

PubMed

Kitjaruwankul, Sunan; Wapeesittipan, Pattama; Boonamnaj, Panisak; Sompornpisut, Pornthep

2016-01-28

Structural data of CorA Mg(2+) channels show that the five Gly-Met-Asn (GMN) motifs at the periplasmic loop of the pentamer structure form a molecular scaffold serving as a selectivity filter. Unfortunately, knowledge about the cation selectivity of Mg(2+) channels remains limited. Since Mg(2+) in aqueous solution has a strong first hydration shell and apparent second hydration sphere, the coordination structure of Mg(2+) in a CorA selectivity filter is expected to be different from that in bulk water. Hence, this study investigated the hydration structure and ligand coordination of Mg(2+) in a selectivity filter of CorA using molecular dynamics (MD) simulations. The simulations reveal that the inner-shell structure of Mg(2+) in the filter is not significantly different from that in aqueous solution. The major difference is the characteristic structural features of the outer shell. The GMN residues engage indirectly in the interactions with the metal ion as ligands in the second shell of Mg(2+). Loss of hydrogen bonds between inner- and outer-shell waters observed from Mg(2+) in bulk water is mostly compensated by interactions between waters in the first solvation shell and the GMN motif. Some water molecules in the second shell remain in the selectivity filter and become less mobile to support the metal binding. Removal of Mg(2+) from the divalent cation sensor sites of the protein had an impact on the structure and metal binding of the filter. From the results, it can be concluded that the GMN motif enhances the affinity of the metal binding site in the CorA selectivity filter by acting as an outer coordination ligand.

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).

Neptune Polar Orbiter with Probes

NASA Technical Reports Server (NTRS)

Bienstock, Bernard; Atkinson, David; Baines, Kevin; Mahaffy, Paul; Steffes, Paul; Atreya, Sushil; Stern, Alan; Wright, Michael; Willenberg, Harvey; Smith, David;

Outer-valence Electron Spectra of Prototypical Aromatic Heterocycles from an Optimally Tuned Range-Separated Hybrid Functional

PubMed Central

2014-01-01

Density functional theory with optimally tuned range-separated hybrid (OT-RSH) functionals has been recently suggested [Refaely-Abramson et al. Phys. Rev. Lett.2012, 109, 226405] as a nonempirical approach to predict the outer-valence electronic structure of molecules with the same accuracy as many-body perturbation theory. Here, we provide a quantitative evaluation of the OT-RSH approach by examining its performance in predicting the outer-valence electron spectra of several prototypical gas-phase molecules, from aromatic rings (benzene, pyridine, and pyrimidine) to more complex organic systems (terpyrimidinethiol and copper phthalocyanine). For a range up to several electronvolts away from the frontier orbital energies, we find that the outer-valence electronic structure obtained from the OT-RSH method agrees very well (typically within ∼0.1–0.2 eV) with both experimental photoemission and theoretical many-body perturbation theory data in the GW approximation. In particular, we find that with new strategies for an optimal choice of the short-range fraction of Fock exchange, the OT-RSH approach offers a balanced description of localized and delocalized states. We discuss in detail the sole exception found—a high-symmetry orbital, particular to small aromatic rings, which is relatively deep inside the valence state manifold. Overall, the OT-RSH method is an accurate DFT-based method for outer-valence electronic structure prediction for such systems and is of essentially the same level of accuracy as contemporary GW approaches, at a reduced computational cost. PMID:24839410

Characterization of N-linked oligosaccharides assembled on secretory recombinant glucose oxidase and cell wall mannoproteins from the methylotrophic yeast Hansenula polymorpha.

PubMed

Kim, Moo Woong; Rhee, Sang Ki; Kim, Jeong-Yoon; Shimma, Yoh-ichi; Chiba, Yasunori; Jigami, Yoshifumi; Kang, Hyun Ah

2004-03-01

Presently almost no information is available on the oligosaccharide structure of the glycoproteins secreted from the methylotrophic yeast Hansenula polymorpha, a promising host for the production of recombinant proteins. In this study, we analyze the size distribution and structure of N-linked oligosaccharides attached to the recombinant glycoprotein glucose oxidase (GOD) and the cell wall mannoproteins obtained from H. polymorpha. Oligosaccharide profiling showed that the major oligosaccharide species derived from the H. polymorpha-secreted recombinant GOD (rGOD) had core-type structures (Man(8-12)GlcNAc(2)). Analyses using anti-alpha 1,3-mannose antibody and exoglycosidases specific for alpha 1,2- or alpha 1,6-mannose linkages revealed that the mannose outer chains of N-glycans on the rGOD have very short alpha 1,6 extensions and are mainly elongated in alpha 1,2-linkages without a terminal alpha 1,3-linked mannose addition. The N-glycans released from the H. polymorpha mannoproteins were shown to contain mostly mannose in their outer chains, which displayed almost identical size distribution and structure to those of H. polymorpha-derived rGOD. These results strongly indicate that the outer chain processing of N-glycans by H. polymorpha significantly differs from that by Saccharomyces cerevisiae, thus generating much shorter mannose outer chains devoid of terminal alpha 1,3-linked mannoses.

Studies in geophysics: The Earth's electrical environment

NASA Astrophysics Data System (ADS)

The Earth is electrified. Between the surface and the outer reaches of the atmosphere, there is a global circuit that is maintained by worldwide thunderstorm activity and by upper atmospheric dynamo processes. The highest voltages approach a billion volts and are generated within thunderclouds, where lightning is a visual display of the cloud's electrical nature. The largest currents in the circuit, approaching a million amperes, are associated with the aurora. Because there have been significant advances in understanding many of the component parts of the global electric circuit (lightning, cloud electrification, electrical processes in specific atmospheric regions, and telluric currents), a principal research challenge is to understand how these components interact to shape the global circuit. Increased basic understanding in this field has many potential practical applications, including lightning protection, the design of advanced aircraft and spacecraft, and improvements in weather prediction.

Studies in geophysics: The Earth's electrical environment

NASA Technical Reports Server (NTRS)

1986-01-01

The Earth is electrified. Between the surface and the outer reaches of the atmosphere, there is a global circuit that is maintained by worldwide thunderstorm activity and by upper atmospheric dynamo processes. The highest voltages approach a billion volts and are generated within thunderclouds, where lightning is a visual display of the cloud's electrical nature. The largest currents in the circuit, approaching a million amperes, are associated with the aurora. Because there have been significant advances in understanding many of the component parts of the global electric circuit (lightning, cloud electrification, electrical processes in specific atmospheric regions, and telluric currents), a principal research challenge is to understand how these components interact to shape the global circuit. Increased basic understanding in this field has many potential practical applications, including lightning protection, the design of advanced aircraft and spacecraft, and improvements in weather prediction.

Jupiter's first 100 miles

PubMed

Reichhardt, T

1996-04-01

In December, 1995, after a journey of six years, the Galileo probe plunged into Jupiter's atmosphere, becoming the first artificial object to make direct contact with an outer planet. New data supplied by the probe indicated: 1) A new radiation belt around Jupiter ten times stronger than the Van Allen belt around Earth; 2) Jupiter may be much drier than predicted. Its atmosphere contains about as much water as the Sun, but this is subject to instrument calibration uncertainties, and the location of the landing in one of the driest spots on the planet; 3) Jupiter's atmosphere appears to have about three to ten times less lightning than Earth's, while the events are about 10 times stronger, both in terms of size and amount of electrical discharge; and, 4) Jupiter's winds were stronger than expected, increasing with depth, at 330 mph.

ROCKET PORT CLOSURE

DOEpatents

Mattingly, J.T.

1963-02-12

This invention provides a simple pressure-actuated closure whereby windowless observation ports are opened to the atmosphere at preselected altitudes. The closure comprises a disk which seals a windowless observation port in rocket hull. An evacuated instrument compartment is affixed to the rocket hull adjacent the inner surface of the disk, while the outer disk surface is exposed to the atmosphere through which the rocket is traveling. The pressure differential between the evacuated instrument compartment and the relatively high pressure external atmosphere forces the disk against the edge of the observation port, thereby effecting a tight seai. The instrument compartment is evacuated to a pressure equal to the atmospheric pressure existing at the altitude at which it is desiretl that the closure should open. When the rocket reaches this preselected altitude, the inwardly directed atmospheric force on the disk is just equaled by the residual air pressure force within the instrument compartment. Consequently, the closure disk falls away and uncovers the open observation port. The separation of the disk from the rocket hull actuates a switch which energizes the mechanism of a detecting instrument disposed within the instrument compartment. (AE C)

Outer satellite atmospheres: Their nature and planetary interactions

NASA Technical Reports Server (NTRS)

Smyth, W. H.

1981-01-01

Modeling capabilities and initial model calculations are reported for the peculiar directional features of the Io sodium cloud discovered by Pilcher and the extended atomic oxygen atmosphere of Io discovered by Brown. Model results explaining the directional feature by a localized emission from the satellite are encouraging, but as yet, inconclusive; whereas for the oxygen cloud, an escape rate of 1 to 2 x 10 to the 27th power atoms/sec or higher from Io is suggested. Preliminary modeling efforts were also initiated for the extended hydrogen ring-atmosphere of Saturn detected by the Voyager spacecraft and for possible extended atmospheres of some of the smaller satellites located in the E-ring. Continuing research efforts reported for the Io sodium cloud include further refinement in the modeling of the east-west asymmetry data, the asymmetric line profile shape, and the intersection of the cloud with the Io plasma torus. In addition, the completed pre-Voyager modeling of Titan's hydrogen torus is included and the near completed model development for the extended atmosphere of comets is discussed.

Hermetic aluminum radio frequency interconnection and method for making

DOEpatents

Kilgo, Riley D.; Kovacic, Larry; Brow, Richard K.

2000-01-01

The present invention provides a light-weight, hermetic coaxial radio-frequency (RF) interconnection having an electrically conductive outer housing made of aluminum or an aluminum alloy, a central electrical conductor made of ferrous or non-ferrous material, and a cylinder of dielectric material comprising a low-melting-temperature, high-thermal-expansion aluminophosphate glass composition for hermetically sealing between the aluminum-alloy outer housing and the ferrous or non-ferrous center conductor. The entire RF interconnection assembly is made permanently hermetic by thermally fusing the center conductor, glass, and housing concurrently by bringing the glass to the melt point by way of exposure to an atmospheric temperature sufficient to melt the glass, less than 540.degree. C., but that does not melt the center conductor or the outer aluminum or aluminum alloy housing. The composition of the glass used is controlled to provide a suitable low dielectric constant so that an appropriate electrical characteristic impedance, for example 50 ohms, can be achieved for an electrical interconnection that performs well at high radio frequencies and also provides an interconnection maintaining a relatively small physical size.

Chemical Compositions of Kinematically Selected Outer Halo Stars

NASA Astrophysics Data System (ADS)

Zhang, Lan; Ishigaki, Miho; Aoki, Wako; Zhao, Gang; Chiba, Masashi

2009-12-01

Chemical abundances of 26 metal-poor dwarfs and giants are determined from high-resolution and high signal-to-noise ratio spectra obtained with the Subaru/High Dispersion Spectrograph. The sample is selected so that most of the objects have outer-halo kinematics. Self-consistent atmospheric parameters were determined by an iterative procedure based on spectroscopic analysis. Abundances of 13 elements, including α-elements (Mg, Si, Ca, Ti), odd-Z light elements (Na, Sc), iron-peak elements (Cr, Mn, Fe, Ni, Zn), and neutron-capture elements (Y, Ba), are determined by two independent data reduction and local thermodynamic equillibrium analysis procedures, confirming the consistency of the stellar parameters and abundances results. We find a decreasing trend of [α/Fe] with increasing [Fe/H] for the range of -3.5< [Fe/H] <-1, as found by Stephens & Boesgaard. [Zn/Fe] values of most objects in our sample are slightly lower than the bulk of halo stars previously studied. These results are discussed as possible chemical properties of the outer halo in the Galaxy. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Radiolysis and Photolysis of Icy Satellite Surfaces: Experiments and Theory

NASA Technical Reports Server (NTRS)

Cassidy, T.; Coll, P.; Raulin, F.; Carlson, R. W.; Hand, K. P.; Johnson, R. E.; Loeffler, M. J.; Baragiola, R. A.

2010-01-01

The transport and exchange of material between bodies in the outer solar system is often facilitated by their exposure to ionizing radiation. With this in mind we review the effects of energetic ions, electrons and UV photons on materials present in the outer solar system. We consider radiolysis, photolysis, and sputtering of low temperature solids. Radiolysis and photolysis are the chemistry that follows the bond breaking and ionization produced by incident radiation, producing, e.g., O2 and H2 from irradiated H2O ice. Sputtering is the ejection of molecules by incident radiation. Both processes are particularly effective on ices in the outer solar system. Materials reviewed include H2O ice, sulfur-containing compounds (such as S02 and S8), carboncontajning compounds (such as CH4), nitrogen-containing compounds (such as NH3 and N2), and mixtures of those compounds. We also review the effects of ionizing radiation on a mixture of N2 and CH4 gases, as appropriate to Titan's upper atmosphere, where radiolysis and photolysis produce complex organic compounds (tholins).

Transient desorption of water vapor - A potential source of error in upper atmosphere rocket experiments

NASA Technical Reports Server (NTRS)

Kendall, B. R. F.; Weeks, J. O.

1974-01-01

Results of measurements of the outgassing rates of samples of materials and surface finishes used on the outer skins of rocket-borne experiment packages in simulated rocket ascents. The results showed outgassing rates for anodized aluminum in the second minute of flight which are two to three orders of magnitude higher than those given in typical tables of outgassing rates. The measured rates for aluminum with chromate conversion surface coatings were also abnormally high. These abnormally high initial rates fell quickly after about five to ten minutes to values comparable with those in the published literature. It is concluded that anodized and chromate conversion coatings on the aluminum outer surfaces of a sounding rocket experiment package will cause gross distortion of the true water vapor environment.

Heat shield characterization: Outer planet atmospheric entry probe

NASA Technical Reports Server (NTRS)

Mezines, S. A.; Rusert, E. L.; Disser, E. F.

1976-01-01

A full scale carbon phenolic heat shield was fabricated for the Outer Planet Probe in order to demonstrate the feasibility of molding large carbon phenolic parts with a new fabrication processing method (multistep). The sphere-cone heat shield was molded as an integral unit with the nose cap plies configured into a double inverse chevron shape to achieve the desired ply orientation. The fabrication activity was successful and the feasibility of the multistep processing technology was established. Delaminations or unbonded plies were visible on the heat shield and resulted from excessive loss of resin and lack of sufficient pressure applied on the part during the curing cycle. A comprehensive heat shield characterization test program was conducted, including: nondestructive tests with the full scale heat shield and thermal and mechanical property tests with small test specimen.

Evidence for extended chromospheres surrounding red giant stars

NASA Technical Reports Server (NTRS)

Stencel, R. E.

1981-01-01

There is now an increasing amount of both observational evidence and theoretical arguments that regions of partially ionized hydrogen extending several stellar radii are an important feature of red giant and supergiant stars. This evidence is discussed and the implications of the existence of extended chromospheres in terms of the nature of the outer atmospheres of, and mass loss from, cool stars are examined.

Planetary quarantine

NASA Technical Reports Server (NTRS)

1977-01-01

Those areas of future missions which will be impacted by planetary quarantine (PQ) constraints were identified. The specific objectives for this reporting period were (1) to perform an analysis of the effects of PQ on an outer planet atmospheric probe, and (2) to prepare a quantitative illustration of spacecraft microbial reduction resulting from exposure to space environments. The Jupiter Orbiter Probe mission was used as a model for both of these efforts.

Beyond Electric Propulsion: Non-Propulsive Benefits of Nuclear Power for the Exploration of the Outer Solar System

NASA Astrophysics Data System (ADS)

Zubrin, Robert M.

1994-07-01

In the past, most studies dealing with the benefits of space nuclear electric power systems for solar system exploration have focused on the potential of nuclear electric propulsion (NEP) to enhance missions by increasing delivered payload, decreasing LEO mass, or reducing trip time. While important, such mission enhancements have failed to go to the heart of the concerns of the scientific community supporting interplanetary exploration. To put the matter succinctly, scientists don't buy delivered payload - they buy data returned. With nuclear power we can increase both the quantity of data returned, by enormously increasing data communication rates, and the quality of data by enabling a host of active sensing techniques otherwise impossible. These non-propulsive mission enhancement capabilities of space nuclear power have been known in principle for many years, but they have not been adequately documented. As a result, support for the development of space nuclear power by the interplanetary exploration community has been much less forceful than it might otherwise be. In this paper we shall present mission designs that take full advantage of the potential mission enhancements offered by space nuclear power systems in the 10 to 100 kWe range, not just for propulsion, but to radically improve, enrich, and expand the science return itself. Missions considered include orbiter missions to each of the outer planets. It will be shown that be using hybrid trajectories combining chemical propulsion with NEP and (in certain cases) gravity assists, that it is possible, using a Titan IV-Centaur launch vehicle, for high-powered spacecraft to be placed in orbit around each of the outer planets with electric propulsion burn times of less than 4 years. Such hybrid trajectories therefore make the outer solar-system available to near-term nuclear electric power systems. Once in orbit, the spacecraft will utilize multi-kilowatt communication systems, similar to those now employed by the U.S. military, to increase data return far beyond that possible utilizing the 40 W rf traveling wave tube antennas that are the current NASA standard. This higher data rate will make possible very high resolution multi-spectral imaging (with high resolutions both spatially and spectrally), a form of science hitherto impossible in the outer solar system. Large numbers of such images could be returned, allowing the creation of motion pictures of atmospheric phenomenon on a small scale and greatly increasing the probability of capturing transient phenomena such as lighting or volcanic activity. The multi-kilowatt power sources on the spacecraft also enables active sensing, including radar, which could be used to do topographic and subsurface studies of clouded bodies such as Titan, ground penetrating sounding of Pluto, the major planet's moons, and planetoids, and topside sounding of the electrically conductive atmospheres of Jupiter, Saturn, Uranus and Neptune to produce profiles of fluid density, conductivity, and horizontal and vertical velocity as a function of depth and global location. Radio science investigations of planetary atmospheres and ring systems would be greatly enhanced by increased transmitter power. The scientific benefits of utilizing such techniques are discussed, and a comparison is made with the quantity and quality of science that a low-powered spacecraft employing RTGs could return. It is concluded that the non-propulsive benefits of nuclear power for spacecraft exploring the outer solar system are enormous, and taken together with the well documented mission enhancements enabled by electric propulsion fully justify the expenditures needed to bring a space qualified nuclear electric power source into being.

Volatile inventory and early evolution of the planetary atmospheres

NASA Astrophysics Data System (ADS)

Marov, Mikhail Ya.; Ipatov, Sergei I.

Formation of atmospheres of the inner planets involved the concurrent processes of mantle degassing and collisions that culminated during the heavy bombardment. Volatile-rich icy planetesimals impacting on the planets as a late veneer strongly contributed to the volatile inventory. Icy remnants of the outer planet accretion significantly complemented the accumulation of the lithophile and atmophile elements forced out onto the surface of the inner planets from silicate basaltic magma enriched in volatiles. Orbital dynamics of small bodies, including near-Earth asteroids, comets, and bodies from the Edgeworth-Kuiper belt evolving to become inner planet crossers, is addressed to examine different plausible amounts of volatile accretion. The relative importance of comets and chondrites in the delivery of volatiles is constrained by the observed fractionation pattern of noble gas abundances in the atmospheres of inner planets. The following development of the early atmospheres depended on the amount of volatiles expelled from the interiors and deposited by impactors, while the position of the planet relative to the Sun and its mass affected its climatic evolution.

Acetylene as fast food: implications for development of life on anoxic primordial Earth and in the outer solar system.

PubMed

Oremland, Ronald S; Voytek, Mary A

2008-02-01

Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered approximately 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem.

Acetylene as fast food: Implications for development of life on anoxic primordial earth and in the outer solar system

USGS Publications Warehouse

Oremland, R.S.; Voytek, M.A.

2008-01-01

Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem. ?? Mary Ann Liebert, Inc.

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

Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1

NASA Astrophysics Data System (ADS)

de Wit, Julien; Wakeford, Hannah R.; Lewis, Nikole K.; Delrez, Laetitia; Gillon, Michaël; Selsis, Frank; Leconte, Jérémy; Demory, Brice-Olivier; Bolmont, Emeline; Bourrier, Vincent; Burgasser, Adam J.; Grimm, Simon; Jehin, Emmanuël; Lederer, Susan M.; Owen, James E.; Stamenković, Vlada; Triaud, Amaury H. M. J.

2018-03-01

Seven temperate Earth-sized exoplanets readily amenable for atmospheric studies transit the nearby ultracool dwarf star TRAPPIST-1 (refs 1,2). Their atmospheric regime is unknown and could range from extended primordial hydrogen-dominated to depleted atmospheres3-6. Hydrogen in particular is a powerful greenhouse gas that may prevent the habitability of inner planets while enabling the habitability of outer ones6-8. An atmosphere largely dominated by hydrogen, if cloud-free, should yield prominent spectroscopic signatures in the near-infrared detectable during transits. Observations of the innermost planets have ruled out such signatures9. However, the outermost planets are more likely to have sustained such a Neptune-like atmosphere10, 11. Here, we report observations for the four planets within or near the system's habitable zone, the circumstellar region where liquid water could exist on a planetary surface12-14. These planets do not exhibit prominent spectroscopic signatures at near-infrared wavelengths either, which rules out cloud-free hydrogen-dominated atmospheres for TRAPPIST-1 d, e and f, with significance of 8σ, 6σ and 4σ, respectively. Such an atmosphere is instead not excluded for planet g. As high-altitude clouds and hazes are not expected in hydrogen-dominated atmospheres around planets with such insolation15, 16, these observations further support their terrestrial and potentially habitable nature.

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.

[Adsorption Capacity of the Air Particulate Matter in Urban Landscape Plants in Different Polluted Regions of Beijing].

PubMed

Zhang, Wei-kang; Wang, Bing; Niu, Xiang

2015-07-01

Urban landscape plants, as one of the important factors of the urban ecosystem, play an important role in stagnating airborne particulates and purifying urban atmospheric environment. In this article, six kinds of common garden plants were studied, and aerosol generator (QRJZFSQ-I) was used to measure the ability of their leaves to stagnate atmospheric particulates (TSP and PM2.5) in different polluted regions. Meanwhile, environmental scanning electron microscope was used to observe changes in the leaf structure of the tested tree species. The results showed: (1)Among the tested tree species, the ability of coniferous species to stagnate atmospheric particulates was higher than that of broad-leaved species per unit leaf area. Pinus tabuliformis stagnated the highest volume of (3. 89± 0. 026) µg . m-2, followed by Pinus bungeana of (2. 82 ± 0. 392) µg . cm-2, and Populus tomentosa stagnated the minimum of (2. 00 ± 0. 118) µg . cm-2; (2) Through observing the leaf microstructure morphology, coniferous species were found to have tightly packed stomas, stoma density and surface roughness higher than those of broad-leaved species, and they could also secrete oil; (3) In different polluted regions, the leaves of the same tree species showed significant difference in stagnating TSP. Per unit leaf area, the tree species leaves situated around the 5th Ring Road had higher ability to absorb TSP than the tree species leaves at Botanical Garden, while their abilities to absorb PM2.5 showed no significant difference; (4) In different polluted regions, significantly adaptive changes were found in leaf structure. Comparing to the region with light pollution, the outer epidermal cells of the plant leaves in region with heavy pollution shrank, and the roughness of the leaf skin textures as well as the stomatal frequency and villous length increased. In spite of the significant changes in plant leaves exposed to the heavy pollution, these plants could still maintain normal and healthy growth.

Tholins as Coloring Agents on Pluto and Other Icy Solar System Bodies

NASA Technical Reports Server (NTRS)

Cruikshank, Dale

2016-01-01

Tholins are refractory organic solids of complex structure and high molecular weight, with a wide range of color ranging from yellow and orange to dark red, and through tan to black. They are made in the laboratory by energy deposition (photons or charged particles) in gases and ices containing the simple molecules (e.g., N2, CH4, CO) found in planetary atmospheres or condensed on planetary surfaces. They are widely implicated in providing the colors and albedos, particularly in the region 0.3-1.0 microns, of several outer Solar System bodies, including Pluto, as well as aerosols in planetary atmospheres such as Titan. Recent color images of Pluto with the New Horizons spacecraft show concentrations of coloring agent(s) in some regions of the surface, and apparent near-absence in other regions. Tholins that may to some degree represent surface chemistry on Pluto have been synthesized in the laboratory by energetic processing of mixtures of the ices (N2, CH4, CO) known on Pluto's surface, or the same molecules in the gas phase. Details of the composition and yield vary with experimental conditions. Chemical analysis of Pluto ice tholins shows evidence of amides, carboxylic acids, urea, carbodiimides, and nitriles. Aromatic/olefinic, amide, and other functional groups are identified in XANES analysis. The ice tholins produced by e- irradiation have a higher concentration of N than UV ice tholins, with N/C approx. 0.9 (versus approx. 0.5 for UV tholins) and O/C approx.0.2. Raman spectra of the electron tholin show a high degree of structural disorder, while strong UV fluorescence indicates a large aromatic content. EUV photolysis of a Pluto gaseous atmosphere analog yields pale yellow solids relatively transparent in the visual, and with aliphatic CH bonds prominent in IR spectra. This or similar material may be responsible for Pluto's hazes.

Solar wind disturbances in th outer heliosphere caused by successive solar flares from the same active region

NASA Technical Reports Server (NTRS)

Akasofu, S. I.; Hakamada, K.

1983-01-01

Solar wind disturbances caused by successive flares from the same active region are traced to about 20 AU, using the modeling method developed by Hakamada and Akasofu (1982). It is shown that the flare-generated shock waves coalesce with the co-rotating interaction region of the interplanetary magnetic field, resulting in a large-scale magnetic field structure in the outer heliosphere. Such a structure may have considerable effects on the propagation of galactic cosmic rays.

THE SKIN | Functional morphology of the integumentary system in fishes

USGS Publications Warehouse

Elliott, D.G.; Farrell, Anthony P.

2011-01-01

The integument that covers the outer surface of a fish’s body and fins is a multifunctional organ, with morphological features highly adapted to carry out these functions. The integument consists of two layers. The outer layer, the epidermis, is essentially cellular in structure, comprised of a multilayered epithelium that usually includes specialized cells. The inner layer, the dermis, is primarily a fibrous structure with relatively few cells, although it may contain scales, nerves, blood vessels, adipose tissue, and pigment cells.

Measurements of Photospheric and Chromospheric Magnetic Fields

NASA Astrophysics Data System (ADS)

Lagg, Andreas; Lites, Bruce; Harvey, Jack; Gosain, Sanjay; Centeno, Rebecca

2017-09-01

The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous. To a large extent, their importance for the thermodynamics in the solar photosphere is determined by the total magnetic flux. Whereas in low-flux quiet Sun regions, magnetic structures are shuffled around by the motion of granules, the high-flux areas like sunspots or pores effectively suppress convection, leading to a temperature decrease of up to 3000 K. The importance of magnetic fields to the conditions in higher atmospheric layers, the chromosphere and corona, is indisputable. Magnetic fields in both active and quiet regions are the main coupling agent between the outer layers of the solar atmosphere, and are therefore not only involved in the structuring of these layers, but also for the transport of energy from the solar surface through the corona to the interplanetary space. Consequently, inference of magnetic fields in the photosphere, and especially in the chromosphere, is crucial to deepen our understanding not only for solar phenomena such as chromospheric and coronal heating, flares or coronal mass ejections, but also for fundamental physical topics like dynamo theory or atomic physics. In this review, we present an overview of significant advances during the last decades in measurement techniques, analysis methods, and the availability of observatories, together with some selected results. We discuss the problems of determining magnetic fields at smallest spatial scales, connected with increasing demands on polarimetric sensitivity and temporal resolution, and highlight some promising future developments for their solution.

Design of a new static micromixer having simple structure and excellent mixing performance.

PubMed

Kamio, Eiji; Ono, Tsutomu; Yoshizawa, Hidekazu

2009-06-21

A novel micromixer with simple construction and excellent mixing performance is developed. The micromixer is composed of two stainless steel tubes with different diameters: one is an outer tube and another is an inner tube which fits in the outer tube. In this micromixer, one reactant fluid flows in the mixing zone from the inner tube and the other flows from the outer tube. The excellent mixing performance is confirmed by comparing the results of a Villermaux/Dushman reaction with those for the other micromixers. The developed micromixer has a mixing cascade with multiple means and an asymmetric structure to achieve effective mixing. The excellent mixing performance of the developed micromixer suggests that serial addition of multiple phenomena for mixing will give us an efficient micromixing.

The Solar-Stellar Connection (NAG5-6124: SOHO Guest Investigator Program)

NASA Technical Reports Server (NTRS)

Ayres, Thomas R.

1997-01-01

The following is a final report from the SOHO Guest Investigator program to use the SUMER far-UV spectrometer to obtain imaging spectroscopy in support of the goals of the so-called "solar-stellar connection." In particular, a major emphasis was utilization of the long-slit time-resolved maps of the solar surface in bright far-UV emission lines to deduce how particular aspects of the temporally and spatially averaged line profiles trace back to individual structural features of the magnetically disturbed outer atmosphere; to help interpret the unresolved line profiles from high quality stellar observations (say, with the Space Telescope Imaging Spectrograph). The researchers served two tours of duty in the SOHO Operations Center as SUMER planners, during which time we conducted an extensive series of observing programs. These can be divided into three general categories: surface mapping, translimb spectroscopy, and active region diagnostics. We have analyzed some of the large volumes of data to the point where we have presented them in poster papers, and in invited papers at national and international meetings. Listed below are the titles of the preliminary publications we have written, including brief abstracts to indicate the main results. (1) Chromospheric structure and Dynamics-- Observations -- The chromosphere is a highly structured dynamic 'layer' of the solar outer atmosphere. Here, not only are the effects of mechanical heating first evident (moving upward in altitude from the deep photosphere), but also the amount of nonradiative energy deposited is far greater than in the albeit much hotter overlying transition region and corona. Further, the chromosphere is by far the thickest zone of the solar atmosphere with respect to the pressure scale height. A major goal of stellar astrophysics is to understand how the chromosphere is heated and why it adopts its peculiar structure. A cursory examination of solar filtergrams and high-resolution movies demonstrates that much of the chromospheric "action" must be occurring on fine spatial scales and short times; particularly in the cell interior transient brightenings, but also in the longer-lived network fragments. That regime of investigation is far removed from what one usually associates with "synoptic" measurements. Nevertheless, synoptic observations of chromospheric indices, filtergrams, and globally-averaged profile parameters not only can provide important insight concerning the crucial role of the cycle-variable part of the solar magnetic field; but they also can forge a key link with analogous measurements of the stars, where often the phenomena can be significantly exaggerated from the solar case, but high spatial resolution reconnaissance is not even a remote possibility. In addition to discussing the synoptic aspects of chromospheric structure and dynamics, I summarized new insights into the general problem of the solar chromosphere that have been obtained recently with the SUMER far-ultraviolet spectrometer on SOHO. (2) CO and the Temperature Structure of the Solar Atmosphere -- The surface layers of the Sun provide a crucial boundary condition for many of the processes that occur in the deep interior. The stratification of the outer solar atmosphere once was thought to be well understood. However, studies of thermally sensitive molecular absorptions in the infrared revealed puzzling anomalies. Strong lines of the CO fundamental vibration-rotation bands near 5 microns showed very cool temperatures at the extreme limb, and remarkable off-limb emissions extending well into the supposedly hot chromosphere. The conflicting pictures of the photosphere/chromosphere interface, from the widely separated wavelength regimes, has raised suspicions that those "layers" of the atmosphere are much more inhomogeneous than previously suspected. One proposal is that the low chromosphere is dominated by cool gas, the "COmosphere," which is threaded by a network of persistent small-scale hot magnetic filaments and occasionally disrupted by localized acoustic disturbances. The COmosphere is capped by the merged fields of the network elements in the chromospheric "canopy." (3) Translimb Spectroscopy with SOHO/SUMER -- We have used SUMER to obtain deep exposures of the 1300-1400 A spectrum, at the extreme limb and off-limb. Previous "translimb" studies in the thermal infrared had revealed remarkable extensions of cold material (T is approximately equal to 3000 K)-traced by carbon monoxide emission lines-into the heart of the hot chromosphere. A main objective of our program was to search for corresponding far-UV signatures of the "thermally-bifurcated" low chromosphere; for example, radiatively fluoresced emissions of the CO A-X 4th-positive system (collisional excitation would be negligible in cold gas). We conducted two separate observing programs with SUMER. Both made use of the 1 inch-diameter circular aperture, translated across the limb in the minimum motor step increments of 0."375, along the central meridian in the Northern polar coronal hole. The first program executed for nine hours beginning 19UT 25 Oct 1996. The full wavelength range was 1340-1400 A. It was recorded in two overlapping segments, placing key regions of the spectrum alternately on the KBr and bare parts of the detector, to help isolate 2nd-order features. Each segment was integrated for 500 s, and 32 pairs were obtained to span a 12" swath centered on the optical limb. The second program was conducted 00-09UT 01 Dec 1996. It consisted of a single wavelength setting (1300-1340 A) with exposure time 500 s, but twice the spatial coverage of the earlier series: 64 steps, for a total displacement of 24". The strong chromospheric resonance lines of atomic oxygen (1302-1305 A) and ionized carbon (1334-1335 A) were observed on the bare part of the MCP camera.

Inflatable nested toroid structure

NASA Technical Reports Server (NTRS)

Johnson, Christopher J. (Inventor); Raboin, Jasen L. (Inventor); Spexarth, Gary R. (Inventor)

2011-01-01

An inflatable structure comprises at least two generally toroidal, inflatable modules. When in a deployed mode, the first, inner module has a major diameter less than that of a second, outer module and is positioned within the inner circumference of the outer module such that the first module is nested circumferentially alongside the second module. The inflatable structure, in a non-deployed, non-inflated mode, is of compact configuration and adapted to be transported to a site of deployment. When deployed, the inflatable structure is of substantially increased interior volume. In one embodiment, access between the interior of the first module and the second module is provided by at least one port or structural pass-through. In another embodiment, the inflatable structure includes at least one additional generally toroidal module external of and circumferentially surrounding the second module.

Apparatus for assembling space structure

NASA Technical Reports Server (NTRS)

Johnston, J. D.; Tuggle, R. H., Jr.; Burch, J. L.; Clark, K. H. (Inventor)

1978-01-01

An apparatus for producing a structure in outer space from rolls of prepunched ribbon or sheet material that are transported from the earth to the apparatus located in outer space is described. The apparatus spins the space structure similar to a spider spinning a web utilizing the prepunched ribbon material. The prepunched ribbon material is fed through the apparatus and is shaped into a predetermined channel-shaped configuration. Trusses are punched out of the ribbon and are bent downwardly and attached to a track which normally is a previously laid sheet of material. The size of the overall space structure may be increased by merely attaching an additional roll of sheet material to the apparatus.

Inner and Outer Recursive Neural Networks for Chemoinformatics Applications.

PubMed

Urban, Gregor; Subrahmanya, Niranjan; Baldi, Pierre

2018-02-26

Deep learning methods applied to problems in chemoinformatics often require the use of recursive neural networks to handle data with graphical structure and variable size. We present a useful classification of recursive neural network approaches into two classes, the inner and outer approach. The inner approach uses recursion inside the underlying graph, to essentially "crawl" the edges of the graph, while the outer approach uses recursion outside the underlying graph, to aggregate information over progressively longer distances in an orthogonal direction. We illustrate the inner and outer approaches on several examples. More importantly, we provide open-source implementations [available at www.github.com/Chemoinformatics/InnerOuterRNN and cdb.ics.uci.edu ] for both approaches in Tensorflow which can be used in combination with training data to produce efficient models for predicting the physical, chemical, and biological properties of small molecules.

Gas turbine structural mounting arrangement between combustion gas duct annular chamber and turbine vane carrier

DOEpatents

Wiebe, David J.; Charron, Richard C.; Morrison, Jay A.

2016-10-18

A gas turbine engine ducting arrangement (10), including: an annular chamber (14) configured to receive a plurality of discrete flows of combustion gases originating in respective can combustors and to deliver the discrete flows to a turbine inlet annulus, wherein the annular chamber includes an inner diameter (52) and an outer diameter (60); an outer diameter mounting arrangement (34) configured to permit relative radial movement and to prevent relative axial and circumferential movement between the outer diameter and a turbine vane carrier (20); and an inner diameter mounting arrangement (36) including a bracket (64) secured to the turbine vane carrier, wherein the bracket is configured to permit the inner diameter to move radially with the outer diameter and prevent axial deflection of the inner diameter with respect to the outer diameter.

Assembly of the β-Barrel Outer Membrane Proteins in Gram-Negative Bacteria, Mitochondria, and Chloroplasts

PubMed Central

Misra, Rajeev

2012-01-01

In the last decade, there has been an explosion of publications on the assembly of β-barrel outer membrane proteins (OMPs), which carry out diverse cellular functions, including solute transport, protein secretion, and assembly of protein and lipid components of the outer membrane. Of the three outer membrane model systems—Gram-negative bacteria, mitochondria and chloroplasts—research on bacterial and mitochondrial systems has so far led the way in dissecting the β-barrel OMP assembly pathways. Many exciting discoveries have been made, including the identification of β-barrel OMP assembly machineries in bacteria and mitochondria, and potentially the core assembly component in chloroplasts. The atomic structures of all five components of the bacterial β-barrel assembly machinery (BAM) complex, except the β-barrel domain of the core BamA protein, have been solved. Structures reveal that these proteins contain domains/motifs known to facilitate protein-protein interactions, which are at the heart of the assembly pathways. While structural information has been valuable, most of our current understanding of the β-barrel OMP assembly pathways has come from genetic, molecular biology, and biochemical analyses. This paper provides a comparative account of the β-barrel OMP assembly pathways in Gram-negative bacteria, mitochondria, and chloroplasts. PMID:27335668

Multi-scale Structural and Tensile Mechanical Response of Annulus Fibrosus to Osmotic Loading

PubMed Central

Han, Woojin M.; Nerurkar, Nandan L.; Smith, Lachlan J.; Jacobs, Nathan T.; Mauck, Robert L.; Elliott, Dawn M.

2012-01-01

This study investigates differential multi-scale structure and function relationships of the outer and inner annulus fibrosus (AF) to osmotic swelling in different buffer solutions by quantifying tensile mechanics, GAG content, water content and tissue swelling, and collagen fibril ultrastructure. In the outer AF, the tensile modulus decreased by over 70% with 0.15M PBS treatment but was unchanged with 2M PBS treatment. Moreover, the modulus loss following 0.15M PBS treatment was reversed when followed by 2M PBS treatment, potentially from increased interfibrillar and interlamellar shearing associated with fibril swelling. In contrast, the inner AF tensile modulus was unchanged by 0.15M PBS treatment and increased following 2M treatment. Transmission electron microscopy revealed that the mean collagen fibril diameters of the untreated outer and inner AF were 87.8 ± 27.9 and 71.0 ± 26.9 nm, respectively. In the outer AF, collagen fibril swelling was observed with both 0.15M and 2M PBS treatments, but inherently low GAG content remained unchanged. In the inner AF, 2M PBS treatment caused fibril swelling and GAG loss, suggesting that GAG plays a role in maintaining the structure of collagen fibrils leading to modulation of the native tissue mechanical properties. These results demonstrate important regional variations in structure and composition, and their influence on the heterogeneous mechanics of the AF. Moreover, because the composition and structure is altered as a consequence of progressive disc degeneration, quantification of these interactions is critical for study of the AF pathogenesis of degeneration and tissue engineering. PMID:22314837

Machine-Thermal Coupling Stresses Analysis of the Fin-Type Structural Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Yue, Hao; Chen, Dongbo; Qin, Delei; Chen, Zijian

2017-05-01

The design structure and heat-transfer mechanism of a thermoelectric generator (TEG) determine its body temperature state. Thermal stress and thermal deformation generated by the temperature variation directly affect the stress state of thermoelectric modules (TEMs). Therefore, the rated temperature and pressing force of TEMs are important parameters in TEG design. Here, the relationships between structural of a fin-type TEG (FTEG) and these parameters are studied by modeling and "machine-thermal" coupling simulation. An indirect calculation method is adopted in the coupling simulation. First, numerical heat transfer calculations of a three-dimensional FTEG model are conducted according to an orthogonal simulation table. The influences of structural parameters for heat transfer in the channel and outer fin temperature distribution are analyzed. The optimal structural parameters are obtained and used to simulate temperature field of the outer fins. Second, taking the thermal calculation results as the initial condition, the thermal-solid coupling calculation is adopted. The thermal stresses of outer fin, mechanical force of spring-angle pressing mechanism, and clamping force on a TEM are analyzed. The simulation results show that the heat transfer area of the inner fin and the physical parameters of the metal materials are the keys to determining the FTEG temperature field. The pressing mechanism's mechanical force can be reduced by reducing the outer fin angle. In addition, a corrugated cooling water pipe, which has cooling and spring functionality, is conducive to establishing an adaptable clamping force to avoid the TEMs being crushed by the thermal stresses in the body.

Impact-generated winds on Venus: Causes and effects

NASA Technical Reports Server (NTRS)

Schultz, Pater H.

1992-01-01

The pressure of the dense atmosphere of Venus significantly changes the appearance of ejecta deposits relative to craters on the Moon and Mercury. Conversely, specific styles and sequences of ejecta emplacement can be inferred to represent different intensities of atmospheric response winds acting over different timescales. Three characteristic timescales can be inferred from the geologic record: surface scouring and impactor-controlled (angle and direction) initiation of the long fluidized run-out flows; nonballistic emplacement of inner, radar-bright ejecta facies and radar-dark outer facies; and very late reworking of surface materials. These three timescales roughly correspond to processes observed in laboratory experiments that can be scaled to conditions on Venus (with appropriate assumptions): coupling between the atmosphere and earlytime vapor/melt (target and impactor) that produces an intense shock that subsequently evolves into blast/response winds; less energetic dynamic response of the atmosphere to the outward-moving ballistic ejecta curtain that generates nonthermal turbulent eddies; and late recovery of the atmosphere to impact-generated thermal and pressure gradients expressed as low-energy but long-lived winds. These different timescales and processes can be viewed as the atmosphere equivalent of shock melting, material motion, and far-field seismic response in the target. The three processes (early Processes, Atmospheric Processes, and Late Recovery Winds) are discussed at length.

A suppression of differential rotation in Jupiter’s deep interior

NASA Astrophysics Data System (ADS)

Guillot, T.; Miguel, Y.; Militzer, B.; Hubbard, W. B.; Kaspi, Y.; Galanti, E.; Cao, H.; Helled, R.; Wahl, S. M.; Iess, L.; Folkner, W. M.; Stevenson, D. J.; Lunine, J. I.; Reese, D. R.; Biekman, A.; Parisi, M.; Durante, D.; Connerney, J. E. P.; Levin, S. M.; Bolton, S. J.

2018-03-01

Jupiter’s atmosphere is rotating differentially, with zones and belts rotating at speeds that differ by up to 100 metres per second. Whether this is also true of the gas giant’s interior has been unknown, limiting our ability to probe the structure and composition of the planet. The discovery by the Juno spacecraft that Jupiter’s gravity field is north–south asymmetric and the determination of its non-zero odd gravitational harmonics J3, J5, J7 and J9 demonstrates that the observed zonal cloud flow must persist to a depth of about 3,000 kilometres from the cloud tops. Here we report an analysis of Jupiter’s even gravitational harmonics J4, J6, J8 and J10 as observed by Juno and compared to the predictions of interior models. We find that the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere. Moreover, we find that the atmospheric zonal flow extends to more than 2,000 kilometres and to less than 3,500 kilometres, making it fully consistent with the constraints obtained independently from the odd gravitational harmonics. This depth corresponds to the point at which the electric conductivity becomes large and magnetic drag should suppress differential rotation. Given that electric conductivity is dependent on planetary mass, we expect the outer, differentially rotating region to be at least three times deeper in Saturn and to be shallower in massive giant planets and brown dwarfs.

Silicide Coating Fabricated by HAPC/SAPS Combination to Protect Niobium Alloy from Oxidation.

PubMed

Sun, Jia; Fu, Qian-Gang; Guo, Li-Ping; Wang, Lu

2016-06-22

A combined silicide coating, including inner NbSi2 layer and outer MoSi2 layer, was fabricated through a two-step method. The NbSi2 was deposited on niobium alloy by halide activated pack cementation (HAPC) in the first step. Then, supersonic atmospheric plasma spray (SAPS) was applied to obtain the outer MoSi2 layer, forming a combined silicide coating. Results show that the combined coating possessed a compact structure. The phase constitution of the combined coating prepared by HAPC and SAPS was NbSi2 and MoSi2, respectively. The adhesion strength of the combined coating increased nearly two times than that for single sprayed coating, attributing to the rougher surface of the HAPC-bond layer whose roughness increased about three times than that of the grit-blast substrate. After exposure at 1200 °C in air, the mass increasing rate for single HAPC-silicide coating was 3.5 mg/cm(2) because of the pest oxidation of niobium alloy, whereas the combined coating displayed better oxidation resistance with a mass gain of only 1.2 mg/cm(2). Even more, the combined coating could significantly improve the antioxidation ability of niobium based alloy at 1500 °C. The good oxidation resistance of the combined silicide coating was attributed to the integrity of the combined coating and the continuous SiO2 protective scale provided by the oxidation of MoSi2.

Transport in Rayleigh-stable experimental Taylor-Couette flow and granular electrification in a shaking experiment

NASA Astrophysics Data System (ADS)

Nordsiek, Freja

This dissertation consists of two projects: Rayleigh-stable Taylor-Couette flow and granular electrification. Taylor-Couette flow is the fluid flow in the gap between two cylinders rotating at different rates. Azimuthal velocity profiles, dye visualization, and inner cylinder torques were measured on two geometrically similar Taylor-Couettes with axial boundaries attached to the outer cylinder, the Maryland and Twente T3C experiments. This was done in the Rayleigh stable regime, where the specific angular momentum increases radially, which is relevant to astrophysical and geophysical flows and in particular, stellar and planetary accretion disks. The flow substantially deviates from laminar Taylor-Couette flow beginning at moderate Reynolds number. Angular momentum is primarily transported to the axial boundaries instead of the outer cylinder due to Ekman pumping when the inner cylinder is rotating faster than the outer cylinder. A phase diagram was constructed from the transitions identified from torque measurements taken over four decades of the Reynolds number. Flow angular velocities larger and smaller than both cylinders were found. Together, these results indicate that experimental Taylor-Couette with axial boundaries attached to the outer cylinder is an imperfect model for accretion disk flows. Thunderstorms, thunder-snow, volcanic ash clouds, and dust storms all display lightning, which results from electrification of droplets and particles in the atmosphere. While lightning is fairly well understood (plasma discharge), the mechanisms that result in million-volt differences across the storm are not. A novel granular electrification experiment was upgraded and used to study some of these mechanisms in the lab. The relative importance of collective interactions between particles versus particle properties (material, size, etc.) on collisional electrification was investigated. While particle properties have an order of magnitude effect on the strength of macroscopic electrification, all particle types electrified with dynamics that suggest a major role for collective interactions in electrification. Moreover, mixing two types of particles together does not lead to increased electrification except for specific combinations of particles which clump, which further points towards the importance of collective phenomena. These results help us better understand the mechanisms of electrification and lightning generation in certain atmospheric systems.

Effects of atmospheric pressure plasma jet with floating electrode on murine melanoma and fibroblast cells

NASA Astrophysics Data System (ADS)

Xu, G.; Liu, J.; Yao, C.; Chen, S.; Lin, F.; Li, P.; Shi, X.; Zhang, Guan-Jun

2017-08-01

Atmospheric pressure cold plasma jets have been recently shown as a highly promising tool in certain cancer therapies. In this paper, an atmospheric pressure plasma jet (APPJ) with a one inner floating and two outer electrode configuration using helium gas for medical applications is developed. Subjected to a range of applied voltages with a frequency of 19.8 kHz at a fixed rate of gas flow (i.e., 3 l/min), electrical and optical characteristics of the APPJ are investigated. Compared with the device only with two outer electrodes, higher discharge current, longer jet, and more active species in the plasma plume at the same applied voltage together with the lower gas breakdown voltage can be achieved through embedding a floating inner electrode. Employing the APPJ with a floating electrode, the effects of identical plasma treatment time durations on murine melanoma cancer and normal fibroblast cells cultured in vitro are evaluated. The results of cell viability, cell apoptosis, and DNA damage detection show that the plasma can inactivate melanoma cells in a time-dependent manner from 10 s to 60 s compared with the control group (p < 0.05). However, for fibroblast cells compared with their control group, the plasma with treatment time from 30 s to 60 s can induce significant changes (p < 0.05), showing a less cytotoxic effect than that on melanoma cells at the same treatment time. The different basal reactive oxygen species level and antioxidant superoxide dismutase level of two kinds of cells may account for their different responses towards the identical plasma exposure.

Laboratory measurements of the W band (3.2 mm) properties of phosphine (PH3) and ammonia (NH3) under simulated conditions for the outer planets

NASA Astrophysics Data System (ADS)

Mohammed, Priscilla N.; Steffes, Paul G.

2004-07-01

A model, based on the Van Vleck-Weisskopf line shape, was developed for the centimeter-wavelength opacity of PH3, which provides an order of magnitude improvement over previous models [Hoffman et al., 2001]. New laboratory measurements indicate that the model is also accurate at 94 GHz (3.2 mm) under conditions for the outer planets. Measurements of the opacity and refractivity of PH3 in a hydrogen/helium (H2/He) atmosphere were conducted at 94 GHz (3.2 mm) at pressures of 0.5 and 2 bars and at temperatures of 293 K and 213 K. Additionally, new high-precision laboratory measurements of the opacity and refractivity of NH3 in an H2/He atmosphere were conducted at the same frequency at pressures from 0.5 to 2 bars and at temperatures of 204 K, 211 K, and 290 K. Results show that existing models, which predict NH3 opacity in an H2/He environment, understate the absorption due to the pressure broadened rotational lines. A new model is proposed for use at 94 GHz (3.2 mm) which uses a Ben-Reuven line shape [Ben-Reuven, 1966] for the inversion lines and a Kinetic line shape [Gross, 1955] for the rotational lines. Results of measurements of both PH3 and NH3 can be used to better interpret maps of Saturn's emission at this wavelength and can potentially be used to deduce spatial variations in the abundances of both gases in the atmosphere of Saturn.

HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: DEPENDENCE ON PLANETARY MASS

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

Kopparapu, Ravi Kumar; Ramirez, Ramses M.; Kasting, James F.

2014-06-01

The ongoing discoveries of extra-solar planets are unveiling a wide range of terrestrial mass (size) planets around their host stars. In this Letter, we present estimates of habitable zones (HZs) around stars with stellar effective temperatures in the range 2600 K-7200 K, for planetary masses between 0.1 M {sub ⊕} and 5 M {sub ⊕}. Assuming H{sub 2}O-(inner HZ) and CO{sub 2}-(outer HZ) dominated atmospheres, and scaling the background N{sub 2} atmospheric pressure with the radius of the planet, our results indicate that larger planets have wider HZs than do smaller ones. Specifically, with the assumption that smaller planets will havemore » less dense atmospheres, the inner edge of the HZ (runaway greenhouse limit) moves outward (∼10% lower than Earth flux) for low mass planets due to larger greenhouse effect arising from the increased H{sub 2}O column depth. For larger planets, the H{sub 2}O column depth is smaller, and higher temperatures are needed before water vapor completely dominates the outgoing longwave radiation. Hence the inner edge moves inward (∼7% higher than Earth's flux). The outer HZ changes little due to the competing effects of the greenhouse effect and an increase in albedo. New, three-dimensional climate model results from other groups are also summarized, and we argue that further, independent studies are needed to verify their predictions. Combined with our previous work, the results presented here provide refined estimates of HZs around main-sequence stars and provide a step toward a more comprehensive analysis of HZs.« less

Selective Oxidation of a 0.1C-6Mn-2Si Third Generation Advanced High-Strength Steel During Dew-Point Controlled Annealing

NASA Astrophysics Data System (ADS)

Pourmajidian, Maedeh; McDermid, Joseph R.

2018-03-01

The present study investigates the selective oxidation of a 0.1C-6Mn-2Si medium-Mn advanced high-strength steel during austenization annealing heat treatments as a function of process atmosphere oxygen partial pressure and annealing time. It was determined that the surface oxide growth kinetics followed a parabolic rate law with the minimum rate belonging to the lowest oxygen partial pressure atmosphere at a dew point of 223 K (- 50 °C). The chemistry of the surface and subsurface oxides was studied using STEM + EELS on the sample cross sections, and it was found that the surface oxides formed under the 223 K (- 50 °C) dew-point atmosphere consisted of a layered configuration of SiO2, MnSiO3, and MnO, while in the case of the higher pO2 process atmospheres, only MnO was detected at the surface. Consistent with the Wagner calculations, it was shown that the transition to internal oxidation for Mn occurred under the 243 K (- 30 °C) and 278 K (+ 5 °C) dew-point atmospheres. However, the predictions of the external to internal oxidation for Si using the Wagner model did not correlate well with the experimental findings nor did the predictions of the Mataigne et al. model for multi-element alloys. Investigations of the internal oxide network at the grain boundaries revealed a multilayer oxide structure composed of amorphous SiO2 and crystalline MnSiO3, respectively, at the oxide core and outer shell. A mechanism for the formation of the oxide morphologies observed, based on kinetic and thermodynamic factors, was proposed. It is expected that only the fine and nodule-like MnO oxides formed on the surface of the samples annealed under the 278 K (+ 5 °C) dew-point process atmosphere for 60 and 120 seconds are sufficiently thin and of the desired dispersed morphology to promote reactive wetting by the molten galvanizing bath.

Structural features and lipid binding domain of tubulin on biomimetic mitochondrial membranes

PubMed Central

Hoogerheide, David P.; Noskov, Sergei Y.; Jacobs, Daniel; Bergdoll, Lucie; Silin, Vitalii; Worcester, David L.; Abramson, Jeff; Nanda, Hirsh; Rostovtseva, Tatiana K.; Bezrukov, Sergey M.

2017-01-01

Dimeric tubulin, an abundant water-soluble cytosolic protein known primarily for its role in the cytoskeleton, is routinely found to be associated with mitochondrial outer membranes, although the structure and physiological role of mitochondria-bound tubulin are still unknown. There is also no consensus on whether tubulin is a peripheral membrane protein or is integrated into the outer mitochondrial membrane. Here the results of five independent techniques—surface plasmon resonance, electrochemical impedance spectroscopy, bilayer overtone analysis, neutron reflectometry, and molecular dynamics simulations—suggest that α-tubulin’s amphipathic helix H10 is responsible for peripheral binding of dimeric tubulin to biomimetic “mitochondrial” membranes in a manner that differentiates between the two primary lipid headgroups found in mitochondrial membranes, phosphatidylethanolamine and phosphatidylcholine. The identification of the tubulin dimer orientation and membrane-binding domain represents an essential step toward our understanding of the complex mechanisms by which tubulin interacts with integral proteins of the mitochondrial outer membrane and is important for the structure-inspired design of tubulin-targeting agents. PMID:28420794

Structural Insights into Ail-Mediated Adhesion in Yersinia pestis

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

Yamashita, Satoshi; Lukacik, Petra; Barnard, Travis J.

2012-01-30

Ail is an outer membrane protein from Yersinia pestis that is highly expressed in a rodent model of bubonic plague, making it a good candidate for vaccine development. Ail is important for attaching to host cells and evading host immune responses, facilitating rapid progression of a plague infection. Binding to host cells is important for injection of cytotoxic Yersinia outer proteins. To learn more about how Ail mediates adhesion, we solved two high-resolution crystal structures of Ail, with no ligand bound and in complex with a heparin analog called sucrose octasulfate. We identified multiple adhesion targets, including laminin and heparin,more » and showed that a 40 kDa domain of laminin called LG4-5 specifically binds to Ail. We also evaluated the contribution of laminin to delivery of Yops to HEp-2 cells. This work constitutes a structural description of how a bacterial outer membrane protein uses a multivalent approach to bind host cells.« less

Photoreceptor Outer Segment-like Structures in Long-Term 3D Retinas from Human Pluripotent Stem Cells.

PubMed

Wahlin, Karl J; Maruotti, Julien A; Sripathi, Srinivasa R; Ball, John; Angueyra, Juan M; Kim, Catherine; Grebe, Rhonda; Li, Wei; Jones, Bryan W; Zack, Donald J

2017-04-10

The retinal degenerative diseases, which together constitute a leading cause of hereditary blindness worldwide, are largely untreatable. Development of reliable methods to culture complex retinal tissues from human pluripotent stem cells (hPSCs) could offer a means to study human retinal development, provide a platform to investigate the mechanisms of retinal degeneration and screen for neuroprotective compounds, and provide the basis for cell-based therapeutic strategies. In this study, we describe an in vitro method by which hPSCs can be differentiated into 3D retinas with at least some important features reminiscent of a mature retina, including exuberant outgrowth of outer segment-like structures and synaptic ribbons, photoreceptor neurotransmitter expression, and membrane conductances and synaptic vesicle release properties consistent with possible photoreceptor synaptic function. The advanced outer segment-like structures reported here support the notion that 3D retina cups could serve as a model for studying mature photoreceptor development and allow for more robust modeling of retinal degenerative disease in vitro.

Recent advances in coronal heating

NASA Astrophysics Data System (ADS)

De Moortel, Ineke; Browning, Philippa

2015-04-01

The solar corona, the tenuous outer atmosphere of the Sun, is orders of magnitude hotter than the solar surface. This 'coronal heating problem' requires the identification of a heat source to balance losses due to thermal conduction, radiation and (in some locations) convection. The review papers in this Theo Murphy meeting issue present an overview of recent observational findings, large- and small-scale numerical modelling of physical processes occurring in the solar atmosphere and other aspects which may affect our understanding of the proposed heating mechanisms. At the same time, they also set out the directions and challenges which must be tackled by future research. In this brief introduction, we summarize some of the issues and themes which reoccur throughout this issue.

Momentum and energy deposition in late-type stellar atmospheres and winds

NASA Technical Reports Server (NTRS)

Hartmann, L.; Macgregor, K. B.

1980-01-01

The present study calculates the response of the outer atmospheres of cool low-gravity stars to the passage of the mechanical energy fluxes of solar magnitude in the form of acoustic waves and Alfven waves. It is shown that Alfven waves are efficient in generating outflow, and can account for the order of magnitude of observed mass loss in late-type luminous stars. However, unless these magnetic waves undergo some dissipation within several stellar radii of the surface, the predicted terminal velocities of the resulting stellar winds are far too high. Alfven wave dissipation should give rise to extended warm chromospheres in low-gravity late-type stars, a prediction which can be observationally tested.

Cassini atmospheric chemistry mapper. Volume 1. Investigation and technical plan

NASA Technical Reports Server (NTRS)

Smith, William Hayden; Baines, Kevin Hays; Drossart, Pierre; Fegley, Bruce; Orton, Glenn; Noll, Keith; Reitsema, Harold; Bjoraker, Gordon L.

1990-01-01

The Cassini Atmospheric Chemistry Mapper (ACM) enables a broad range of atmospheric science investigations for Saturn and Titan by providing high spectral and spatial resolution mapping and occultation capabilities at 3 and 5 microns. ACM can directly address the major atmospheric science objectives for Saturn and for Titan, as defined by the Announcement of Opportunity, with pivotal diagnostic measurements not accessible to any other proposed Cassini instrument. ACM determines mixing ratios for atmospheric molecules from spectral line profiles for an important and extensive volume of the atmosphere of Saturn (and Jupiter). Spatial and vertical profiles of disequilibrium species abundances define Saturn's deep atmosphere, its chemistry, and its vertical transport phenomena. ACM spectral maps provide a unique means to interpret atmospheric conditions in the deep (approximately 1000 bar) atmosphere of Saturn. Deep chemistry and vertical transport is inferred from the vertical and horizontal distribution of a series of disequilibrium species. Solar occultations provide a method to bridge the altitude range in Saturn's (and Titan's) atmosphere that is not accessible to radio science, thermal infrared, and UV spectroscopy with temperature measurements to plus or minus 2K from the analysis of molecular line ratios and to attain an high sensitivity for low-abundance chemical species in the very large column densities that may be achieved during occultations for Saturn. For Titan, ACM solar occultations yield very well resolved (1/6 scale height) vertical mixing ratios column abundances for atmospheric molecular constituents. Occultations also provide for detecting abundant species very high in the upper atmosphere, while at greater depths, detecting the isotopes of C and O, constraining the production mechanisms, and/or sources for the above species. ACM measures the vertical and horizontal distribution of aerosols via their opacity at 3 microns and, particularly, at 5 microns. ACM recovers spatially-resolved atmospheric temperatures in Titan's troposphere via 3- and 5-microns spectral transitions. Together, the mixing ratio profiles and the aerosol distributions are utilized to investigate the photochemistry of the stratosphere and consequent formation processes for aerosols. Finally, ring opacities, observed during solar occultations and in reflected sunlight, provide a measurement of the particle size and distribution of ring material. ACM will be the first high spectral resolution mapping spectrometer on an outer planet mission for atmospheric studies while retaining a high resolution spatial mapping capability. ACM, thus, opens an entirely new range of orbital scientific studies of the origin, physio-chemical evolution and structure of the Saturn and Titan atmospheres. ACM provides high angular resolution spectral maps, viewing nadir and near-limb thermal radiation and reflected sunlight; sounds planetary limbs, spatially resolving vertical profiles to several atmospheric scale heights; and measures solar occultations, mapping both atmospheres and rings. ACM's high spectral and spatial resolution mapping capability is achieved with a simplified Fourier Transform spectrometer with a no-moving parts, physically compact design. ACM's simplicity guarantees an inherent stability essential for reliable performance throughout the lengthy Cassini Orbiter mission.

The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed by Herschel. I. Evidence of clumps, multiple arcs, and a linear bar-like structure

NASA Astrophysics Data System (ADS)

Decin, L.; Cox, N. L. J.; Royer, P.; Van Marle, A. J.; Vandenbussche, B.; Ladjal, D.; Kerschbaum, F.; Ottensamer, R.; Barlow, M. J.; Blommaert, J. A. D. L.; Gomez, H. L.; Groenewegen, M. A. T.; Lim, T.; Swinyard, B. M.; Waelkens, C.; Tielens, A. G. G. M.

2012-12-01

Context. The interaction between stellar winds and the interstellar medium (ISM) can create complex bow shocks. The photometers on board the Herschel Space Observatory are ideally suited to studying the morphologies of these bow shocks. Aims: We aim to study the circumstellar environment and wind-ISM interaction of the nearest red supergiant, Betelgeuse. Methods.Herschel PACS images at 70, 100, and 160 μm and SPIRE images at 250, 350, and 500 μm were obtained by scanning the region around Betelgeuse. These data were complemented with ultraviolet GALEX data, near-infrared WISE data, and radio 21 cm GALFA-HI data. The observational properties of the bow shock structure were deduced from the data and compared with hydrodynamical simulations. Results: The infrared Herschel images of the environment around Betelgeuse are spectacular, showing the occurrence of multiple arcs at ~6-7' from the central target and the presence of a linear bar at ~9'. Remarkably, no large-scale instabilities are seen in the outer arcs and linear bar. The dust temperature in the outer arcs varies between 40 and 140 K, with the linear bar having the same colour temperature as the arcs. The inner envelope shows clear evidence of a non-homogeneous clumpy structure (beyond 15''), probably related to the giant convection cells of the outer atmosphere. The non-homogeneous distribution of the material even persists until the collision with the ISM. A strong variation in brightness of the inner clumps at a radius of ~2' suggests a drastic change in mean gas and dust density ~32 000 yr ago. Using hydrodynamical simulations, we try to explain the observed morphology of the bow shock around Betelgeuse. Conclusions: Different hypotheses, based on observational and theoretical constraints, are formulated to explain the origin of the multiple arcs and the linear bar and the fact that no large-scale instabilities are visible in the bow shock region. We infer that the two main ingredients for explaining these phenomena are a non-homogeneous mass-loss process and the influence of the Galactic magnetic field. The hydrodynamical simulations show that a warm interstellar medium, reflecting a warm neutral or partially ionized medium, or a higher temperature in the shocked wind also prevent the growth of strong instabilities. The linear bar is probably an interstellar structure illuminated by Betelgeuse itself. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices (including movies) are available in electronic form at http://www.aanda.org

Signatures of broken protoplanetary discs in scattered light and in sub-millimetre observations

NASA Astrophysics Data System (ADS)

Facchini, Stefano; Juhász, Attila; Lodato, Giuseppe

2018-02-01

Spatially resolved observations of protoplanetary discs are revealing that their inner regions can be warped or broken from the outer disc. A few mechanisms are known to lead to such 3D structures; among them, the interaction with a stellar companion. We perform a 3D SPH simulation of a circumbinary disc misaligned by 60° with respect to the binary orbital plane. The inner disc breaks from the outer regions, precessing as a rigid body and leading to a complex evolution. As the inner disc precesses, the misalignment angle between the inner and outer discs varies by more than 100°. Different snapshots of the evolution are post-processed with a radiative transfer code, in order to produce observational diagnostics of the process. Even though the simulation was produced for the specific case of a circumbinary disc, most of the observational predictions hold for any disc hosting a precessing inner rim. Synthetic scattered light observations show strong azimuthal asymmetries, where the pattern depends strongly on the misalignment angle between the inner and outer discs. The asymmetric illumination of the outer disc leads to azimuthal variations of the temperature structure, in particular in the upper layers, where the cooling time is short. These variations are reflected in asymmetric surface brightness maps of optically thick lines, as CO J = 3-2. The kinematical information obtained from the gas lines is unique in determining the disc structure. The combination of scattered light images and (sub-)mm lines can distinguish between radial inflow and misaligned inner disc scenarios.

K2-106, a system containing a metal-rich planet and a planet of lower density

NASA Astrophysics Data System (ADS)

Guenther, E. W.; Barragán, O.; Dai, F.; Gandolfi, D.; Hirano, T.; Fridlund, M.; Fossati, L.; Chau, A.; Helled, R.; Korth, J.; Prieto-Arranz, J.; Nespral, D.; Antoniciello, G.; Deeg, H.; Hjorth, M.; Grziwa, S.; Albrecht, S.; Hatzes, A. P.; Rauer, H.; Csizmadia, Sz.; Smith, A. M. S.; Cabrera, J.; Narita, N.; Arriagada, P.; Burt, J.; Butler, R. P.; Cochran, W. D.; Crane, J. D.; Eigmüller, Ph.; Erikson, A.; Johnson, J. A.; Kiilerich, A.; Kubyshkina, D.; Palle, E.; Persson, C. M.; Pätzold, M.; Sabotta, S.; Sato, B.; Shectman, St. A.; Teske, J. K.; Thompson, I. B.; Van Eylen, V.; Nowak, G.; Vanderburg, A.; Winn, J. N.; Wittenmyer, R. A.

2017-12-01

Aims: Planets in the mass range from 2 to 15 M⊕ are very diverse. Some of them have low densities, while others are very dense. By measuring the masses and radii, the mean densities, structure, and composition of the planets are constrained. These parameters also give us important information about their formation and evolution, and about possible processes for atmospheric loss. Methods: We determined the masses, radii, and mean densities for the two transiting planets orbiting K2-106. The inner planet has an ultra-short period of 0.57 days. The period of the outer planet is 13.3 days. Results: Although the two planets have similar masses, their densities are very different. For K2-106b we derive Mb=8.36-0.94+0.96 M⊕, Rb = 1.52 ± 0.16 R⊕, and a high density of 13.1-3.6+5.4 g cm-3. For K2-106c, we find Mc=5.8-3.0+3.3 M⊕, Rc=2.50-0.26+0.27 R⊕ and a relatively low density of 2.0-1.1+1.6 g cm-3. Conclusions: Since the system contains two planets of almost the same mass, but different distances from the host star, it is an excellent laboratory to study atmospheric escape. In agreement with the theory of atmospheric-loss processes, it is likely that the outer planet has a hydrogen-dominated atmosphere. The mass and radius of the inner planet is in agreement with theoretical models predicting an iron core containing 80-30+20% of its mass. Such a high metal content is surprising, particularly given that the star has an ordinary (solar) metal abundance. We discuss various possible formation scenarios for this unusual planet. The results are partly based on observations obtained at the European Southern Observatory at Paranal, Chile in program 098.C-0860(A). This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. The article is also partly based on observations with the TNG, NOT. This work has also made use of data from the European Space Agency (ESA) mission Gaia (http://https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://https://www.cosmos.esa.int/web/gaia/dpac/consortium).The RV measurements are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A93

Method and system including a double rotary kiln pyrolysis or gasification of waste material

DOEpatents

McIntosh, M.J.; Arzoumanidis, G.G.

1997-09-02

A method is described for destructively distilling an organic material in particulate form wherein the particulates are introduced through an inlet into one end of an inner rotating kiln ganged to and coaxial with an outer rotating kiln. The inner and outer kilns define a cylindrical annular space with the inlet being positioned in registry with the axis of rotation of the ganged kilns. During operation, the temperature of the wall of the inner rotary kiln at the inlet is not less than about 500 C to heat the particulate material to a temperature in the range of from about 200 C to about 900 C in a pyrolyzing atmosphere to reduce the particulate material as it moves from the one end toward the other end. The reduced particulates including char are transferred to the annular space between the inner and the outer rotating kilns near the other end of the inner rotating kiln and moved longitudinally in the annular space from near the other end toward the one end in the presence of oxygen to combust the char at an elevated temperature to produce a waste material including ash. Also, heat is provided which is transferred to the inner kiln. The waste material including ash leaves the outer rotating kiln near the one end and the pyrolysis vapor leaves through the particulate material inlet. 5 figs.

Method and system including a double rotary kiln pyrolysis or gasification of waste material

DOEpatents

McIntosh, Michael J.; Arzoumanidis, Gregory G.

1997-01-01

A method of destructively distilling an organic material in particulate form wherein the particulates are introduced through an inlet into one end of an inner rotating kiln ganged to and coaxial with an outer rotating kiln. The inner and outer kilns define a cylindrical annular space with the inlet being positioned in registry with the axis of rotation of the ganged kilns. During operation, the temperature of the wall of the inner rotary kiln at the inlet is not less than about 500.degree. C. to heat the particulate material to a temperature in the range of from about 200.degree. C. to about 900.degree. C. in a pyrolyzing atmosphere to reduce the particulate material as it moves from the one end toward the other end. The reduced particulates including char are transferred to the annular space between the inner and the outer rotating kilns near the other end of the inner rotating kiln and moved longitudinally in the annular space from near the other end toward the one end in the presence of oxygen to combust the char at an elevated temperature to produce a waste material including ash. Also, heat is provided which is transferred to the inner kiln. The waste material including ash leaves the outer rotating kiln near the one end and the pyrolysis vapor leaves through the particulate material inlet.

Temporal variation in leaf nitrogen partitioning of a broad-leaved evergreen tree, Quercus myrsinaefolia.

PubMed

Yasumura, Yuko; Ishida, Atsushi

2011-01-01

We examined temporal changes in the amount of nitrogenous compounds in leaves from the outer and inner parts of the crown of Quercus myrsinaefolia growing in a seasonal climate. Throughout the leaf life span, metabolic protein and Rubisco content closely correlated with total nitrogen content, while structural protein content was relatively stable after full leaf expansion. Chlorophyll content was affected by shading as well as total nitrogen content in outer leaves that were overtopped by new shoots in the second year. Outer leaves showed a large seasonal variation in photosynthetic nitrogen-use efficiency (PNUE; the light-saturated photosynthetic rate per unit leaf nitrogen content) during the first year of their life, with PNUE decreasing from the peak in summer towards winter. Outer and inner leaves both showed age-related decline in PNUE in the second year. There were no such drastic changes in leaf nitrogen partitioning that could explain seasonal and yearly variations in PNUE. Nitrogen resorption occurred in overwintering leaves in spring. Metabolic protein explained the majority of nitrogen being resorbed, whereas structural protein, which was low in degradability, contributed little to nitrogen resorption.

Mechanism of Cd2+-coordination during Slow Inactivation in Potassium Channels

PubMed Central

Raghuraman, H.; Cordero-Morales, Julio F.; Jogini, Vishwanath; Pan, Albert C.; Kollewe, Astrid; Roux, Benoît; Perozo, Eduardo

2013-01-01

Summary In K+ channels, rearrangements of the pore outer-vestibule have been associated with C-type inactivation gating. Paradoxically, the crystal structure of Open/C-type inactivated KcsA suggest these movements to be modest in magnitude. Here, we show that under physiological conditions, the KcsA outer-vestibule undergoes relatively large dynamic rearrangements upon inactivation. External Cd2+ enhances the rate of C-type inactivation in an outer-vestibule cysteine mutant (Y82C) via metal-bridge formation. This effect is not present in a non-inactivating mutant (E71A/Y82C). Tandem dimer and tandem tetramer constructs of equivalent cysteine mutants in KcsA and Shaker K+ channels demonstrate that these Cd2+ metal bridges are formed only between adjacent subunits. This is well supported by molecular dynamics simulations. Based on the crystal structure of Cd2+-bound Y82C-KcsA in the closed state, together with EPR distance measurements in the KcsA outer-vestibule, we suggest that subunits must dynamically come in close proximity as the channels undergo inactivation. PMID:22771214

Convection of Plasmaspheric Plasma into the Outer Magnetosphere and Boundary Layer Region: Initial Results

NASA Technical Reports Server (NTRS)

Ober, Daniel M.; Horwitz, J. L.

1998-01-01

We present initial results on the modeling of the circulation of plasmaspheric-origin plasma into the outer magnetosphere and low-latitude boundary layer (LLBL), using a dynamic global core plasma model (DGCPM). The DGCPM includes the influences of spatially and temporally varying convection and refilling processes to calculate the equatorial core plasma density distribution throughout the magnetosphere. We have developed an initial description of the electric and magnetic field structures in the outer magnetosphere region. The purpose of this paper is to examine both the losses of plasmaspheric-origin plasma into the magnetopause boundary layer and the convection of this plasma that remains trapped on closed magnetic field lines. For the LLBL electric and magnetic structures we have adopted here, the plasmaspheric plasma reaching the outer magnetosphere is diverted anti-sunward primarily along the dusk flank. These plasmas reach X= -15 R(sub E) in the LLBL approximately 3.2 hours after the initial enhancement of convection and continues to populate the LLBL for 12 hours as the convection electric field diminishes.

Major uncertainties influencing entry probe heat shield design

NASA Technical Reports Server (NTRS)

Congdon, W.

1974-01-01

Factors influencing the design of an outer planet probe heat shield are discussed. Major factors included are: uncertainties in composition and scale height of the planet atmospheres; the augmentation/attenuation of entry heating by ablation products requires more computer study and testing; carbon heat shields, especially carbon phenolic, possessing improved resistance to spallation need developing; and white silica reflecting heat shields with improved resistance to bulk vitrification need further developing.

Titan's Ammonia Feature

NASA Technical Reports Server (NTRS)

Smythe, W.; Nelson, R.; Boryta, M.; Choukroun, M.

2011-01-01

NH3 has long been considered an important component in the formation and evolution of the outer planet satellites. NH3 is particularly important for Titan, since it may serve as the reservoir for atmospheric nitrogen. A brightening seen on Titan starting in 2004 may arise from a transient low-lying fog or surface coating of ammonia. The spectral shape suggests the ammonia is anhydrous, a molecule that hydrates quickly in the presence of water.

Phase Diversity and Polarization Augmented Techniques for Active Imaging

DTIC Science & Technology

2007-03-01

build up a system model for use in algorithm development. 32 IV. Conventional Imaging and Atmospheric Turbulence With an understanding of scalar...28, 59, 115 Cholesky Factorization, 14, 42 C2n, see Turbulence Coherent Image Model, 36 Complete Data, see EM Algorithm Complex Coherence...Data, see EM Algorithm Homotopic, 62 Impulse Response, 34, 44 Incoherent Image Model, 36 Incomplete Data, see EM Algorithm Lo- Turbulence Outer Scale

Open-Section Composite Structural Elements

NASA Technical Reports Server (NTRS)

Loftin, T. A.; Smith, C. A.; Raheb, S. J.; Nowitzky, A. M.

1991-01-01

Report describes investigation of manufacture and mechanical properties of graphite-fiber/aluminum-matrix open-section structural elements; e.g., channels and angle bars. Conducted with view toward using such elements to build lightweight, thermally stable truss structures in outer space. Other applications transport to, and assembly at, remote or otherwise uninviting locations. Advantages include shapes permitting high packing density during shipment, convenient paths for routing tubes, hoses, and cables; accessibility of both inner and outer surfaces for repair; and ease of attachment of additional hardware. Easier and require less equipment to fabricate, and more amenable to automated fabrication and assembly at remote site. Disadvantages, not as resistant to some kinds of deformation under load.

Mass loss from red giants - Results from ultraviolet spectroscopy

NASA Technical Reports Server (NTRS)

Linsky, J. L.

1985-01-01

New instrumentation in space, primarily the IUE spacecraft, has enabled the application of ultraviolet spectroscopic techniques to the determination of physical properties and reliable mass loss rates for red giant winds. One important result is the determination of where in the H-R diagram are found stars with hot outer atmospheres and with cool winds. So far it appears that single cool stars, except perhaps the so-called hybrid stars, have either hot outer atmospheres or cool winds but not both. The C II resonance (1335 A) and intersystem (2325 A) multiplets have been used to derive temperatures, densities, and geometrical extents for the chromospheric portions of red giant winds, with the result that the red giants and the earlier giants with hot coronae have qualitatively different chromospheres. Mass loss rates can now be derived accurately from the analysis of asymmetric emission lines, such as the Mg II resonance lines, and from P Cygni profile lines of atoms in the dominant ionization stage when a hot star is available to probe the wind of a red giant. The Zeta Aur systems, consisting of a K-M supergiant and a main sequence B star are important systems for reliable mass loss rates for the red supergiant components are becoming available.

Laboratory Studies of Low Temperature Rate Coefficients: The Atmospheric Chemistry of the Outer Planets and Titan

NASA Technical Reports Server (NTRS)

Bogan, Denis

1999-01-01

Laboratory measurements have been carried out to determine low temperature chemical rate coefficients of ethynyl radical (C2H) for the atmospheres of the outer planets and their satellites. This effort is directly related to the Cassini mission which will explore Saturn and Titan. A laser-based photolysis/infrared laser probe setup was used to measure the temperature dependence of kinetic rate coefficients from approx. equal to 150 to 350 K for C2H radicals with H2, C2H2, CH4, CD4, C2H4, C2H6, C3H8, n-C4H10, i-C4H10, neo-C5H12, C3H4 (methylacetylene and allene), HCN, and CH3CN. The results revealed discrepancies of an order of magnitude or more compared with the low temperature rate coefficients used in present models. A new Laval nozzle, low Mach number supersonic expansion kinetics apparatus has been constructed, resulting in the first measurements of neutral C2H radical kinetics at 90 K and permitting studies on condensable gases with insufficient vapor pressure at low temperatures. New studies of C 2H with acetylene have been completed.

The origin of carbon monoxide in Neptunes's atmosphere

NASA Technical Reports Server (NTRS)

Lodders, K.; Fegley, B., Jr.

1994-01-01

The CO abundance in the observable atmosphere of Neptune can be plausibly explained by rapid vertical mixing from the deeper atmosphere if Neptune has a greater complement of water than Uranus. Thermochemical equilibrium and kinetic calculations reveal that Neptune must and Uranus may have about 10 times more oxygen than carbon, whereas for Jupiter and Saturn equal enrichments of carbon and oxygen are satifactory to explain the observed CO abundances by deep vertical mixing. Relative to hydrogen and solar composition, the respective enrichment factors for carbon and oxygen are 41, 440 (Neptune); 32, less than or equal 260 (Uranus); 6.6, 6.6 (Saturn); and 2.8, 2.8 (Jupiter). Because water ice is the most refractory ice among the ices assumed to be present in the outer solar nebula, the most massive H2O enrichment is expected for the outermost planet of this group. Thus, Neptune can indeed be regarded as the 'god of the seas.'

Outer-layer manipulators for turbulent drag reduction

NASA Technical Reports Server (NTRS)

Anders, J. B., Jr.

1990-01-01

The last ten years have yielded intriguing research results on aerodynamic boundary outer-layer manipulators as local skin friction reduction devices at low Reynolds numbers; net drag reduction device systems for entire aerodynamic configurations are nevertheless noted to remain elusive. Evidence has emerged for dramatic alterations of the structure of a turbulent boundary layer which persist for long distances downstream and reduce wall shear as a results of any one of several theoretically possible mechanisms. Reduced effectiveness at high Reynolds numbers may, however, limit the applicability of outer-layer manipulators to practical aircraft drag reduction.

Serial turbo trellis coded modulation using a serially concatenated coder

NASA Technical Reports Server (NTRS)

Divsalar, Dariush (Inventor); Dolinar, Samuel J. (Inventor); Pollara, Fabrizio (Inventor)

2010-01-01

Serial concatenated trellis coded modulation (SCTCM) includes an outer coder, an interleaver, a recursive inner coder and a mapping element. The outer coder receives data to be coded and produces outer coded data. The interleaver permutes the outer coded data to produce interleaved data. The recursive inner coder codes the interleaved data to produce inner coded data. The mapping element maps the inner coded data to a symbol. The recursive inner coder has a structure which facilitates iterative decoding of the symbols at a decoder system. The recursive inner coder and the mapping element are selected to maximize the effective free Euclidean distance of a trellis coded modulator formed from the recursive inner coder and the mapping element. The decoder system includes a demodulation unit, an inner SISO (soft-input soft-output) decoder, a deinterleaver, an outer SISO decoder, and an interleaver.

Dust-Corrected Star Formation Rates in Galaxies with Outer Rings

NASA Astrophysics Data System (ADS)

Kostiuk, I.; Silchenko, O.

2018-03-01

The star formation rates SFR, as well as the SFR surface densities ΣSFR and absolute stellar magnitudes MAB, are determined and corrected for interinsic dust absorption for 34 disk galaxies of early morphological types with an outer ring structure and ultraviolet emission from the ring. These characteristic are determined for the outer ring structures and for the galaxies as a whole. Data from the space telescopes GALEX (in the NUV and FUV ultraviolet ranges) and WISE (in the W4 22 μm infrared band) are used. The average relative deviation in the corrected SFR and ΣSFR derived from the NUV and FUV bands is only 19.0%, so their averaged values are used for statistical consideration. The relations between the dust-corrected SFR characteristics, UV colours, the galaxy morphological type, absolute magnitude are illustrated.

High-temperature, flexible, thermal barrier seal

NASA Technical Reports Server (NTRS)

Sirocky, Paul J. (Inventor); Steinetz, Bruce M. (Inventor)

1991-01-01

This device seals the sliding interfaces between structural panels that are roughly perpendicular to each other or whose edges are butted against one another. The nonuniformity of the gap between the panels requires significant flexibility along the seal length. The seal is mounted in a rectangular groove in a movable structural panel. A plurality of particles or balls is densely packed in an outer sheathing. The balls are laterally preloaded to maintain sealing contact with the adjacent wall using a pressurized linear bellows. Distortions in the adjacent panel are accommodated by rearrangement of the particles within the outer sheathing. Leakage through the seal is minimized by densely compacting the internal particles and by maintaining positive preload along the back side of the seal. The braid architecture of the outer sheathing is selected to minimize leakage through the seal and to resist mechanical abrasion.

Designed β-Boomerang Antiendotoxic and Antimicrobial Peptides

PubMed Central

Bhunia, Anirban; Mohanram, Harini; Domadia, Prerna N.; Torres, Jaume; Bhattacharjya, Surajit

2009-01-01

Lipopolysaccharide (LPS), an integral part of the outer membrane of Gram-negative bacteria, is involved in a variety of biological processes including inflammation, septic shock, and resistance to host-defense molecules. LPS also provides an environment for folding of outer membrane proteins. In this work, we describe the structure-activity correlation of a series of 12-residue peptides in LPS. NMR structures of the peptides derived in complex with LPS reveal boomerang-like β-strand conformations that are stabilized by intimate packing between the two aromatic residues located at the 4 and 9 positions. This structural feature renders these peptides with a high ability to neutralize endotoxicity, >80% at 10 nm concentration, of LPS. Replacements of these aromatic residues either with Ala or with Leu destabilizes the boomerang structure with the concomitant loss of antiendotoxic and antimicrobial activities. Furthermore, the aromatic packing stabilizing the β-boomerang structure in LPS is found to be maintained even in a truncated octapeptide, defining a structured LPS binding motif. The mode of action of the active designed peptides correlates well with their ability to perturb LPS micelle structures. Fourier transform infrared spectroscopy studies of the peptides delineate β-type conformations and immobilization of phosphate head groups of LPS. Trp fluorescence studies demonstrated selective interactions with LPS and the depth of insertion into the LPS bilayer. Our results demonstrate the requirement of LPS-specific structures of peptides for endotoxin neutralizations. In addition, we propose that structures of these peptides may be employed to design proteins for the outer membrane. PMID:19520860

Freeze-fracture studies of photoreceptor membranes: new observations bearing upon the distribution of cholesterol

PubMed Central

1983-01-01

We performed electron microscopy of replicas from freeze-fractured retinas exposed during or after fixation to the cholesterol-binding antibiotic, filipin. We observed characteristic filipin-induced perturbations throughout the disk and plasma membranes of retinal rod outer segments of various species. It is evident that a prolonged exposure to filipin in fixative enhances rather than reduces presumptive cholesterol detection in the vertebrate photoreceptor cell. In agreement with the pattern seen in our previous study (Andrews, L.D., and A. I. Cohen, 1979, J. Cell Biol., 81:215-228), filipin- binding in membranes exhibiting particle-free patches seemed largely confined to these patches. Favorably fractured photoreceptors exhibited marked filipin-binding in apical inner segment plasma membrane topologically confluent with and proximate to the outer segment plasma membrane, which was comparatively free of filipin binding. A possible boundary between these differing membrane domains was suggested in a number of replicas exhibiting lower filipin binding to the apical plasma membrane of the inner segment in the area surrounding the cilium. This area contains a structure (Andrews, L. D., 1982, Freeze- fracture studies of vertebrate photoreceptors, In Structure of the Eye, J. G. Hollyfield and E. Acosta Vidrio, editors, Elsevier/North-Holland, New York, 11-23) that resembles the active zones of the nerve terminals for the frog neuromuscular junction. These observations lead us to hypothesize that these structures may function to direct vesicle fusion to occur near them, in a domain of membrane more closely resembling outer than inner segment plasma membrane. The above evidence supports the views that (a) all disk membranes contain cholesterol, but the particle-free patches present in some disks trap cholesterol from contiguous particulate membrane regions; (b) contiguous inner and outer segment membranes may greatly differ in cholesterol content; and (c) the suggested higher cholesterol in the inner segment than in the outer segment plasma membrane may help direct newly inserted photopigment molecules to the outer segment. PMID:6411740

Exhaust gas emissions of a vortex breakdown stabilized combustor

NASA Technical Reports Server (NTRS)

Yetter, R. A.; Gouldin, F. C.

1976-01-01

Exhaust gas emission data are described for a swirl stabilized continuous combustor. The combustor consists of confined concentric jets with premixed fuel and air in the inner jet and air in the outer jet. Swirl may be induced in both inner and outer jets with the sense of rotation in the same or opposite directions (co-swirl and counter-swirl). The combustor limits NO emissions by lean operation without sacrificing CO and unburned hydrocarbon emission performance, when commercial-grade methane and air fired at one atmosphere without preheat are used. Relative swirl direction and magnitude are found to have significant effects on exhaust gas concentrations, exit temperatures, and combustor efficiencies. Counter-swirl gives a large recirculation zone, a short luminous combustion zone, and large slip velocities in the interjet shear layer. For maximum counter-swirl conditions, the efficiency is low.

An experimental investigation of the angular scattering and backscattering behaviors of the simulated clouds of the outer planets

NASA Technical Reports Server (NTRS)

Sassen, K.

1984-01-01

A cryogenic, 50 liter volume Planetary Cloud Simulation Chamber has been constructed to permit the laboratory study of the cloud compositions which are likely to be found in the atmospheres of the outer planets. On the basis of available data, clouds composed of water ice, carbon dioxide, and liquid and solid ammonia and methane, both pure and in various mixtures, have been generated. Cloud microphysical observations have been permitted through the use of a cloud particle slide injector and photomicrography. Viewports in the lower chamber have enabled the collection of cloud backscattering data using 633 and 838 nm laser light, including linear depolarization ratios and complete Stokes parameterization. The considerable technological difficulties associated with the collection of angular scattering patterns within the chamber, however, could not be completely overcome.