Organic haze on Titan and the early Earth

PubMed Central

Trainer, Melissa G.; Pavlov, Alexander A.; DeWitt, H. Langley; Jimenez, Jose L.; McKay, Christopher P.; Toon, Owen B.; Tolbert, Margaret A.

2006-01-01

Recent exploration by the Cassini/Huygens mission has stimulated a great deal of interest in Saturn's moon, Titan. One of Titan's most captivating features is the thick organic haze layer surrounding the moon, believed to be formed from photochemistry high in the CH4/N2 atmosphere. It has been suggested that a similar haze layer may have formed on the early Earth. Here we report laboratory experiments that demonstrate the properties of haze likely to form through photochemistry on Titan and early Earth. We have used a deuterium lamp to initiate particle production in these simulated atmospheres from UV photolysis. Using a unique analysis technique, the aerosol mass spectrometer, we have studied the chemical composition, size, and shape of the particles produced as a function of initial trace gas composition. Our results show that the aerosols produced in the laboratory can serve as analogs for the observed haze in Titan's atmosphere. Experiments performed under possible conditions for early Earth suggest a significant optical depth of haze may have dominated the early Earth's atmosphere. Aerosol size measurements are presented, and implications for the haze layer properties are discussed. We estimate that aerosol production on the early Earth may have been on the order of 1014 g·year−1 and thus could have served as a primary source of organic material to the surface. PMID:17101962

Differences between evolution of Titan's and Earth's rivers - further conclusions

NASA Astrophysics Data System (ADS)

Misiura, Katarzyna; Czechowski, Leszek

2014-05-01

Titan is the only celestial body, beside the Earth, where liquid is present on the surface. Liquid forms a number of lakes and rivers. In our research we use numerical model of the river to determine differences of evolution of rivers on the Earth and on Titan. We have found that transport of sediments on Titan is more effective than on Earth for the same river geometry and discharge. We have found also the theoretical explanations for this conclusion. 2.Introduction Titan is a very special body in the Solar System. It is the only moon that has dense atmosphere and flowing liquid on its surface. The Cassini-Huygens mission has found on Titan meandering rivers, and indicated processes of erosion, transport of solid material and its sedimentation. This paper is aimed to investigate the similarity and differences between these processes on Titan and the Earth. 3. Basic equations of our model The dynamical analysis of the considered rivers is performed using the package CCHE modified for the specific conditions on Titan. The package is based on the Navier-Stokes equations for depth-integrated two dimensional, turbulent flow and three dimensional convection-diffusion equation of sediment transport. 4. Parameters of the model We considered our model for a few kinds of liquid found on Titan. The liquid that falls as a rain (75% methane, 25% nitrogen) has different properties than the fluid forming lakes (74% ethane, 10% methane, 7% propane, 8.5% butane, 0.5% nitrogen). Other parameters of our model are: inflow discharge, outflow level, grain size of sediments etc. For every calculation performed for Titan's river similar calculations are performed for terrestrial ones. 5. Results and Conclusions The results of our simulation show the differences in behaviour of the flow and of sedimentation on Titan and on the Earth. Our preliminary results indicate that transport of material by Titan's rivers is more efficient than by terrestrial rivers of the same geometry parameters

Progressive Climate Change on Titan: Implications for Habitability

NASA Technical Reports Server (NTRS)

Moore, J. M.; A. D. Howard

2014-01-01

Titan's landscape is profoundly shaped by its atmosphere and comparable in magnitude perhaps with only the Earth and Mars amongst the worlds of the Solar System. Like the Earth, climate dictates the intensity and relative roles of fluvial and aeolian activity from place to place and over geologic time. Thus Titan's landscape is the record of climate change. We have investigated three broad classes of Titan climate evolution hypotheses (Steady State, Progressive, and Cyclic), regulated by the role, sources, and availability of methane. We favor the Progressive hypotheses, which we will outline here, then discuss their implication for habitability.

Future Exploration of Titan

NASA Astrophysics Data System (ADS)

Lorenz, R. D.; Titan Decadal Panel Collaboration

2001-11-01

Titan promises to be the Mars of the Outer Solar System - the focus of not only the broadest range of investigations in planetary science but also the focus of public attention. The reasons for exploring Titan are threefold: 1. Titan and Astrobiology : Titan ranks with Mars and Europa as a prime body for astrobiological study due to its abundant organics. Like Europa, it may well have a liquid water interior. 2. Titan - A world in its own right. Titan deserves study even only to put other satellites (its remarkably smaller Saturnian siblings, and its same-sized but volatile-poor Jovian counterparts) in context. The added dimension of an atmosphere makes Titan's origin and evolution particularly interesting. 3. Titan - an environmental laboratory for Earth. Titan will be an unrivalled place to investigate meteorological, oceanographical and other processes. Many of these (e.g. wave generation by wind) are only empirically parameterized - the very different physical parameters of the Titan environment will bring new insights to these phenomena. While Cassini-Huygens will dramatically boost our knowledge of Titan, it will likely only whet our appetite for more. The potential for prebiotic materials at various locations (in particular where liquid water has interacted with photochemical deposits) and the need to monitor Titan's meteorology favor future missions that may exploit Titan's unique thick-atmosphere, low-gravity environment - a mobile platform like an airship or helicopter, able to explore on global scales, but access the surface for in-situ chemical analysis and probe the interior by electromagnetic and seismic means. Such missions have dramatic potential to capture the public's imagination, on both sides of the Atlantic.

Comparative Application of Dimensionless Bankfull Hydraulic Relations for Earth and Titan

NASA Astrophysics Data System (ADS)

Parker, G.

2005-12-01

Recent evidence from the Huygens Probe of the Cassini Mission suggests that Titan, a satellite of Saturn, has rivers of flowing liquid methane which transport disaggregated crustal sediment in the form of ice. Surface images from the Huygens Probe show gravel-sized ice clasts that appear to be well-rounded by fluvial processes. If river morphodynamics on Earth is truly understood at a physical level, then relations that provide reasonable results on Earth ought to provide similarly reasonable results on Titan. These basic relations should be expressed in terms of dimensionless variabes. At least three dimensioned parameters that would be used to form the relevant dimensionless variables can be expected to vary notably between Earth and Titan. These are a) the acceleration of gravity, the kinematic viscosity of the flowing fluid and the submerged specific gravity of the sediment. Dimensionless relations for the threshold of motion, the threshold of significant suspension and bankfull hydraulic geometry that are known to work on Earth are used to predict features of rivers on Titan. Wildcards that make the predictions tentative include the formation of hydrocarbons on Titan that might add a kind of cohesivity not encountered on Earth and a freeze-thaw process of methane that might not be analogous to freeze-thaw processes in high-latitude rivers on Earth.

Seeing, touching and smelling the extraordinarily Earth-like world of Titan

NASA Astrophysics Data System (ADS)

2005-01-01

"We now have the key to understanding what shapes Titan's landscape," said Dr Martin Tomasko, Principal Investigator for the Descent Imager-Spectral Radiometer (DISR), adding: "Geological evidence for precipitation, erosion, mechanical abrasion and other fluvial activity says that the physical processes shaping Titan are much the same as those shaping Earth." Spectacular images captured by the DISR reveal that Titan has extraordinarily Earth-like meteorology and geology. Images have shown a complex network of narrow drainage channels running from brighter highlands to lower, flatter, dark regions. These channels merge into river systems running into lakebeds featuring offshore 'islands' and 'shoals' remarkably similar to those on Earth. Data provided in part by the Gas Chromatograph and Mass Spectrometer (GCMS) and Surface Science Package (SSP) support Dr Tomasko's conclusions. Huygens' data provide strong evidence for liquids flowing on Titan. However, the fluid involved is methane, a simple organic compound that can exist as a liquid or gas at Titan's sub-170°C temperatures, rather than water as on Earth. Titan's rivers and lakes appear dry at the moment, but rain may have occurred not long ago. Deceleration and penetration data provided by the SSP indicate that the material beneath the surface's crust has the consistency of loose sand, possibly the result of methane rain falling on the surface over eons, or the wicking of liquids from below towards the surface. Heat generated by Huygens warmed the soil beneath the probe and both the GCMS and SSP detected bursts of methane gas boiled out of surface material, reinforcing methane's principal role in Titan's geology and atmospheric meteorology -- forming clouds and precipitation that erodes and abrades the surface. In addition, DISR surface images show small rounded pebbles in a dry riverbed. Spectra measurements (colour) are consistent with a composition of dirty water ice rather than silicate rocks. However

Comparative planetology of the history of nitrogen isotopes in the atmospheres of Titan and Mars

NASA Astrophysics Data System (ADS)

Mandt, Kathleen; Mousis, Olivier; Chassefière, Eric

2015-07-01

We present here a comparative planetology study of evolution of 14N/15N at Mars and Titan. Studies show that 14N/15N can evolve a great deal as a result of escape in the atmosphere of Mars, but not in Titan's atmosphere. We explain this through the existence of an upper limit to the amount of fractionation allowed to occur due to escape that is a function of the escape flux and the column density of nitrogen.

Superrotation on Venus, on Titan, and Elsewhere

NASA Astrophysics Data System (ADS)

Read, Peter L.; Lebonnois, Sebastien

2018-05-01

The superrotation of the atmospheres of Venus and Titan has puzzled dynamicists for many years and seems to put these planets in a very different dynamical regime from most other planets. In this review, we consider how to define superrotation objectively and explore the constraints that determine its occurrence. Atmospheric superrotation also occurs elsewhere in the Solar System and beyond, and we compare Venus and Titan with Earth and other planets for which wind estimates are available. The extreme superrotation on Venus and Titan poses some difficult challenges for numerical models of atmospheric circulation, much more difficult than for more rapidly rotating planets such as Earth or Mars. We consider mechanisms for generating and maintaining a superrotating state, all of which involve a global meridional overturning circulation. The role of nonaxisymmetric eddies is crucial, however, but the detailed mechanisms may differ between Venus, Titan, and other planets.

Organic sedimentary deposits in Titan's dry lakebeds: Probable evaporite

USGS Publications Warehouse

Barnes, J.W.; Bow, J.; Schwartz, J.; Brown, R.H.; Soderblom, J.M.; Hayes, A.G.; Vixie, G.; Le, Mouelic S.; Rodriguez, S.; Sotin, Christophe; Jaumann, R.; Stephan, K.; Soderblom, L.A.; Clark, R.N.; Buratti, B.J.; Baines, K.H.; Nicholson, P.D.

2011-01-01

We report the discovery of organic sedimentary deposits at the bottom of dry lakebeds near Titan's north pole in observations from the Cassini Visual and Infrared Mapping Spectrometer (VIMS). We show evidence that the deposits are evaporitic, making Titan just the third known planetary body with evaporitic processes after Earth and Mars, and is the first that uses a solvent other than water. ?? 2011 Elsevier Inc.

Between heaven and Earth: the exploration of Titan.

PubMed

Owen, Tobias C; Niemann, Hasso; Atreya, Sushil; Zolotov, Mikhail Y

2006-01-01

The atmosphere of Titan represents a bridge between the early solar nebula and atmospheres like ours. The low abundances of primordial noble gases in Titan's atmosphere relative to N2 suggest that the icy planetesimals that formed the satellite must have originated at temperatures higher than 75-100 K. Under these conditions, N2 would also be very poorly trapped and thus Titan's nitrogen, like ours, must have arrived as nitrogen compounds, of which ammonia was likely the major component. This temperature constraint also argues against the trapping of methane. Production of this gas on the satellite after formation appears reasonable based on terrestrial examples of serpentinization, disproportionation and reduction of carbon. These processes require rocks, water, suitable catalysts and the variety of primordial carbon compounds that were plausibly trapped in Titan's ices. Application of this same general scenario to Ganymede, Callisto, KBOs and conditions on the very early Earth seems promising.

Human Exploration of Earth's Neighborhood and Mars

NASA Technical Reports Server (NTRS)

Condon, Gerald

2003-01-01

The presentation examines Mars landing scenarios, Earth to Moon transfers comparing direct vs. via libration points. Lunar transfer/orbit diagrams, comparison of opposition class and conjunction class missions, and artificial gravity for human exploration missions. Slides related to Mars landing scenarios include: mission scenario; direct entry landing locations; 2005 opportunity - Type 1; Earth-mars superior conjunction; Lander latitude accessibility; Low thrust - Earth return phase; SEP Earth return sequence; Missions - 200, 2007, 2009; and Mission map. Slides related to Earth to Moon transfers (direct vs. via libration points (L1, L2) include libration point missions, expeditionary vs. evolutionary, Earth-Moon L1 - gateway for lunar surface operations, and Lunar mission libration point vs. lunar orbit rendezvous (LOR). Slides related to lunar transfer/orbit diagrams include: trans-lunar trajectory from ISS parking orbit, trans-Earth trajectories, parking orbit considerations, and landing latitude restrictions. Slides related to comparison of opposition class (short-stay) and conjunction class (long-stay) missions for human exploration of Mars include: Mars mission planning, Earth-Mars orbital characteristics, delta-V variations, and Mars mission duration comparison. Slides related to artificial gravity for human exploration missions include: current configuration, NEP thruster location trades, minor axis rotation, and example load paths.

Dynamical modelling of river deltas on Titan and Earth

NASA Astrophysics Data System (ADS)

Witek, Piotr P.; Czechowski, Leszek

2015-01-01

The surface of Titan hosts a unique Earth-like environment with lakes and rivers, and active 'hydrologic' cycle of methane. We investigate sediment transport in Titanian rivers and deposition in Titanian lakes with particular attention to formation of river deltas. The obtained results are compared with analogous terrestrial processes. The numerical model based on Navier-Stokes equations for depth-integrated two dimensional turbulent flow and additional equations for bed-load and suspended-load sediment transport was used in our research. It is found that transport of icy grains in Titanian rivers is more effective than silicate grains of the same size in terrestrial rivers for the same assumed total discharge. This effect is explained theoretically using dimensionless form of equations or comparing forces acting on the grains. Our calculations confirm previous results (Burr et al., 2006. Icarus. 181, 235-242). We calculate also models with organic sediments of different densities, namely 1500 and 800 kg m-3. We found substantial differences between materials of varying densities on Titan, but they are less pronounced than differences between Titan and Earth.

GEMINI-TITAN (GT)-4 - EARTH-SKY - OUTER SPACE

NASA Image and Video Library

1965-06-03

S65-34776 (3-7 June 1965) --- This photograph shows the Nile Delta, Egypt, the Suez Canal, Israel, Jordan, Syria, Saudi Arabia, and Iraq as seen from the Gemini-Titan 4 (GT-4) spacecraft during its 12th revolution of Earth.

Mars at 43 Million Miles From Earth

NASA Image and Video Library

2001-06-26

NASA Earth-orbiting Hubble Space Telescope took the picture on June 26, 2001 when Mars was approximately 43 million miles 68 million km from Earth -- the closest Mars has ever been to Earth since 1988.

Particle Radiation Sources, Propagation and Interactions in Deep Space, at Earth, the Moon, Mars, and Beyond: Examples of Radiation Interactions and Effects

NASA Astrophysics Data System (ADS)

Schwadron, Nathan A.; Cooper, John F.; Desai, Mihir; Downs, Cooper; Gorby, Matt; Jordan, Andrew P.; Joyce, Colin J.; Kozarev, Kamen; Linker, Jon A.; Mikíc, Zoran; Riley, Pete; Spence, Harlan E.; Török, Tibor; Townsend, Lawrence W.; Wilson, Jody K.; Zeitlin, Cary

2017-11-01

Particle radiation has significant effects for astronauts, satellites and planetary bodies throughout the Solar System. Acute space radiation hazards pose risks to human and robotic exploration. This radiation also naturally weathers the exposed surface regolith of the Moon, the two moons of Mars, and other airless bodies, and contributes to chemical evolution of planetary atmospheres at Earth, Mars, Venus, Titan, and Pluto. We provide a select review of recent areas of research covering the origin of SEPs from coronal mass ejections low in the corona, propagation of events through the solar system during the anomalously weak solar cycle 24 and important examples of radiation interactions for Earth, other planets and airless bodies such as the Moon.

2005 Earth-Mars Round Trip

NASA Technical Reports Server (NTRS)

2000-01-01

This paper presents, in viewgraph form, the 2005 Earth-Mars Round Trip. The contents include: 1) Lander; 2) Mars Sample Return Project; 3) Rover; 4) Rover Size Comparison; 5) Mars Ascent Vehicle; 6) Return Orbiter; 7) A New Mars Surveyor Program Architecture; 8) Definition Study Summary Result; 9) Mars Surveyor Proposed Architecture 2003, 2005 Opportunities; 10) Mars Micromissions Using Ariane 5; 11) Potential International Partnerships; 12) Proposed Integrated Architecture; and 13) Mars Exploration Program Report of the Architecture Team.

Detailed exploration of Titan with a Montgolfiere aerobot

NASA Astrophysics Data System (ADS)

Spilker, T.; Tipex Team

The International Cassini/Huygens (CH) mission has verified the expectation that Saturn's moon Titan offers many opportunities for studying high-priority planetary and astrobiology science objectives. CH results to date show that this world, though entirely alien in its frigid environment, presents an Earth-like and diverse appearance due to the relative balance of competing forces such as geology/tectonics, meteorology, aeronomy, and cosmic impacts. But with the limitations of a single Huygens probe, and a finite number of Cassini flybys limited in proximity and remote sensing resolution by Titan's thick atmosphere and hazes, there is much science to be done there after the CH mission has ended. Detailed exploration of Titan's surface and lower atmosphere, especially for astrobiological objectives, is best addressed by in situ investigations. The atmosphere and its hazes severely restrict orbital remote sensing: Titan cannot be mapped from orbit in the same manner as Mars, at (essentially) arbitrarily high resolution, and limited infrared (IR) windows allow only gross compositional interpretations. After CH indeed there will be further orbital investigations to be carried out, notably completion of the global mapping by Synthetic Aperture Radar and IR mapping spectrometry begun by CH, at the best resolutions practical from orbit. But to fully understand Titan as an evolving, planetary-scale body and an abode of preserved protobiological chemistry will require a platform that has access to, and mobility at, the surface and the lowest few kilometers of the atmosphere. The TiPEx study team weighed the options for Titan in situ exploration, and finds that a mission based on a Montgolfiere (a type of hot-air balloon) aerobot is the best candidate for post-CH exploration. Ground-based platforms of the type used to date on Mars are far too limited in range to sample the diversity of Titan, and do not adequately investigate the lower atmosphere. Titan's cold, dense

Monte Carlo analysis of the Titan III/Transfer Orbit Stage guidance system for the Mars Observer mission

NASA Astrophysics Data System (ADS)

Bell, Stephen C.; Ginsburg, Marc A.; Rao, Prabhakara P.

An important part of space launch vehicle mission planning for a planetary mission is the integrated analysis of guidance and performance dispersions for both booster and upper stage vehicles. For the Mars Observer mission, an integrated trajectory analysis was used to maximize the scientific payload and to minimize injection errors by optimizing the energy management of both vehicles. This was accomplished by designing the Titan III booster vehicle to inject into a hyperbolic departure plane, and the Transfer Orbit Stage (TOS) to correct any booster dispersions. An integrated Monte Carlo analysis of the performance and guidance dispersions of both vehicles provided sensitivities, an evaluation of their guidance schemes and an injection error covariance matrix. The polynomial guidance schemes used for the Titan III variable flight azimuth computations and the TOS solid rocket motor ignition time and burn direction derivations accounted for a wide variation of launch times, performance dispersions, and target conditions. The Mars Observer spacecraft was launched on 25 September 1992 on the Titan III/TOS vehicle. The post flight analysis indicated that a near perfect park orbit injection was achieved, followed by a trans-Mars injection with less than 2sigma errors.

Mercury's Crater-Hosted Hollows: Chalcogenide Pryo-Thermokarst, and Permafrost Analogs on Earth, Mars, and Titan

NASA Astrophysics Data System (ADS)

Kargel, Jeffrey

2013-04-01

MESSENGER has acquired stunning images of pitted, light-toned and variegated light/dark terrains located primarily on the floors—probably impact-melt sheets—of many of Mercury's large craters. Termed "hollows", the pitted terrains are geomorphologically similar to some on Mars formed by sublimation of ice-rich permafrost and to lowland thermokarst on Earth formed by permafrost thaw; to "swiss cheese" terrain forming by sublimation of frozen CO2 at the Martian South Pole; and to suspected hydrocarbon thermokarst at Titan's poles. I shall briefly review some analogs on these other worlds. The most plausible explanation for Mercury's hollows is terrain degradation involving melting or sublimation of heterogeneous chalcogenide and sulfosalt mineral assemblages. I refer to these Mercurian features as pyrothermokarst; the etymological redundancy distinguishes the conditions and mineral agents from the ice-related features on Earth and Mars, though some of the physical processes may be similar. Whereas ice and sulfur have long been suspected and ice recently was discovered in permanently shadowed craters of Mercury's polar regions, the hollows occur down to the equator, where neither ice nor sulfur is plausible. The responsible volatiles must be only slightly volatile on the surface and/or in the upper crust of Mercury's low to middle latitudes at 400-800 K, but they must be capable of either melting or sublimating on geologically long time scales. Under prevailing upper crustal and surface temperatures, chalcophile-rich "permafrost" can undergo either desulfidation or melting reactions that could cause migration or volume changes of the permafrost, and hence lead to collapse and pitting. I propose the initial emplacement of crater-hosted chalcogenides, sulfosalts and related chalcophile materials such as pnictides, in impact-melt pools (involving solid-liquid and silicate-sulfide fractionation) and further differentiation by associated dry or humid fumaroles (solid

Pingos on Earth and Mars

USGS Publications Warehouse

Burr, D.M.; Tanaka, K.L.; Yoshikawa, K.

2009-01-01

Pingos are massive ice-cored mounds that develop through pressurized groundwater flow mechanisms. Pingos and their collapsed forms are found in periglacial and paleoperiglacial terrains on Earth, and have been hypothesized for a wide variety of locations on Mars. This literature review of pingos on Earth and Mars first summarizes the morphology of terrestrial pingos and their geologic contexts. That information is then used to asses hypothesized pingos on Mars. Pingo-like forms (PLFs) in Utopia Planitia are the most viable candidates for pingos or collapsed pingos. Other PLFs hypothesized in the literature to be pingos may be better explained with other mechanisms than those associated with terrestrial-style pingos. ?? 2008 Elsevier Ltd.

Organic matter in the Titan lakes, and comparison with primitive Earth

NASA Astrophysics Data System (ADS)

Khare, Bishun N.; McKay, C.; Wilhite, P.; Beeler, D.; Carter, M.; Schurmeier, L.; Jagota, S.; Kawai, J.; Nna-Mvondo, D.; Cruikshank, D.; Embaye, T.

2013-06-01

Titan is the only world in the solar system besides the Earth that has liquid on its surface. The liquid in the lakes is thought to be composed primarily of ethane with methane and nitrogen in solution. The clouds are thought to be composed of liquid methane drops. Surface liquid is present in polar lakes and in surface materials at equatorial sites. Studying the chemical processing that potentially results from organic material interacting with this liquid is one of the main goals of proposed missions to Titan. We have been engaged in producing tholin under Titan-like conditions for more than three decades, first at the Laboratory for Planetary Studies at Cornell University in collaboration with Late Dr. Carl Sagan and for over a decade at Laboratory for Planetary Studies at NASA Ames Research Center and Carl Sagan Center for the Study of Life in the Universe, SETI Institute. Our focus is to understand the capabilities for analysis of tholin solubility in liquid methane and ethane for flight instruments. Our results are expected to contribute to an understanding of the organic chemistry on Titan and to the development of an explicit and targeted scientific strategy for near term analysis of the products of organic-liquid interactions on Titan. Organics are produced as a haze in Titan's high atmosphere due to photolysis of methane with the Sun's extreme ultraviolet light and subsequent reaction with N. Also tholins are formed at a much higher level on Titan by charged particles of Saturn magnetosphere. However, the presence of organics is not the sole feature, which makes Titan significant to astrobiology; organics are widely present in the outer solar system. The reason Titan is a prime target for future outer solar system missions is the combination of organic material and liquid on the surface; liquid that could over a medium for further organic synthesis. NASA recently selected for further study a Discovery proposal TiME to investigate the chemistry of the

Calibration Image of Earth by Mars Color Imager

NASA Technical Reports Server (NTRS)

2005-01-01

Three days after the Mars Reconnaissance Orbiter's Aug. 12, 2005, launch, the NASA spacecraft was pointed toward Earth and the Mars Color Imager camera was powered up to acquire a suite of color and ultraviolet images of Earth and the Moon. When it gets to Mars, the Mars Color Imager's main objective will be to obtain daily global color and ultraviolet images of the planet to observe martian meteorology by documenting the occurrence of dust storms, clouds, and ozone. This camera will also observe how the martian surface changes over time, including changes in frost patterns and surface brightness caused by dust storms and dust devils.

The purpose of acquiring an image of Earth and the Moon just three days after launch was to help the Mars Color Imager science team obtain a measure, in space, of the instrument's sensitivity, as well as to check that no contamination occurred on the camera during launch. Prior to launch, the team determined that, three days out from Earth, the planet would only be about 4.77 pixels across, and the Moon would be less than one pixel in size, as seen from the Mars Color Imager's wide-angle perspective. If the team waited any longer than three days to test the camera's performance in space, Earth would be too small to obtain meaningful results.

The images were acquired by turning Mars Reconnaissance Orbiter toward Earth, then slewing the spacecraft so that the Earth and Moon would pass before each of the five color and two ultraviolet filters of the Mars Color Imager. The distance to Earth was about 1,170,000 kilometers (about 727,000 miles).

This image shows a color composite view of Mars Color Imager's image of Earth. As expected, it covers only five pixels. This color view has been enlarged five times. The Sun was illuminating our planet from the left, thus only one quarter of Earth is seen from this perspective. North America was in daylight and facing toward the camera at the time the picture was taken; the data

General Education Engagement in Earth and Planetary Science through an Earth-Mars Analog Curriculum

NASA Astrophysics Data System (ADS)

Chan, M. A.; Kahmann-Robinson, J. A.

2012-12-01

The successes of NASA rovers on Mars and new remote sensing imagery at unprecedented resolution can awaken students to the valuable application of Earth analogs to understand Mars processes and the possibilities of extraterrestrial life. Mars For Earthlings (MFE) modules and curriculum are designed as general science content introducing a pedagogical approach of integrating Earth science principles and Mars imagery. The content can be easily imported into existing or new general education courses. MFE learning modules introduce students to Google Mars and JMARS software packages and encourage Mars imagery analysis to predict habitable environments on Mars drawing on our knowledge of extreme environments on Earth. "Mars Mission" projects help students develop teamwork and presentation skills. Topic-oriented module examples include: Remote Sensing Mars, Olympus Mons and Igneous Rocks, Surface Sculpting Forces, and Extremophiles. The learning modules package imagery, video, lab, and in-class activities for each topic and are available online for faculty to adapt or adopt in courses either individually or collectively. A piloted MFE course attracted a wide range of non-majors to non-degree seeking senior citizens. Measurable outcomes of the piloted MFE curriculum were: heightened enthusiasm for science, awareness of NASA programs, application of Earth science principles, and increased science literacy to help students develop opinions of current issues (e.g., astrobiology or related government-funded research). Earth and Mars analog examples can attract and engage future STEM students as the next generation of earth, planetary, and astrobiology scientists.

Nitrogen airglow sources - Comparison of Triton, Titan, and earth

NASA Technical Reports Server (NTRS)

Strobel, Darrell F.; Meier, R. R.; Summers, Michael E.; Strickland, Douglas J.

1991-01-01

The individual contributions of direct solar excitation, photoelectron excitation, and magnetospheric electron excitation of Triton and Titan airglow observed by the Voyager Ultraviolet Spectrometer (UVS) are quantified. The principal spectral features of Triton's airglow are shown to be consistent with precipitation of magnetospheric electrons with power dissipation about 500 million W. Solar excitation rates of the dominant N2 and N(+) emission features are factors of 2-7 weaker than magnetospheric electron excitation. On Titan, the calculated disk center and bright limb N(+) 1085 A intensities due to solar excitation agree with observed values, while the 970 A feature is mostly N21 c5 band emission. The calculated LBH intensity by photoelectrons suggests that magnetospheric electrons play a minor role in Titan's UV airglow. On earth, solar/photoelectron excitation explains the observed N(+) 1085 A and LBH intensites and accounts for only 40 percent of the N(+) 916 A intensity.

The Greenhouse and Anti-Greenhouse Effects on Titan

NASA Technical Reports Server (NTRS)

McKay, C. P.; Cuzzi, Jeffrey N. (Technical Monitor)

1994-01-01

Titan is the largest moon of Saturn and is the only moon in the solar system with a substantial atmosphere. Its atmosphere is mostly made of nitrogen, with a few percent CH4, 0.1% H2 and an uncertain level of Ar (less than 10%). The surface pressure is 1.5 atms and the surface temperature is 95 K, decreasing to 71 at the tropopause before rising to stratospheric temperatures of 180 K. In pressure and composition Titan's atmosphere is the closest twin to Earth's. The surface of Titan remains unknown, hidden by the thick smog layer, but it may be an ocean of liquid methane and ethane. Titan's atmosphere has a greenhouse effect which is much stronger than the Earth's - 92% of the surface warming is due to greenhouse radiation. However an organic smog layer in the upper atmosphere produces an anti-greenhouse effect that cuts the greenhouse warming in half - removing 35% of the incoming solar radiation. Models suggest that during its formation Titan's atmosphere was heated to high temperatures due to accretional energy. This was followed by a cold Triton-like period which gradually warmed to the present conditions. The coupled greenhouse and haze anti-greenhouse may be relevant to recent suggestions for haze shielding of a CH4 - NH3 early atmosphere on Earth or Mars. When the NASA/ESA mission to the Saturn System, Cassini, launches in a few years it will carry a probe that will be sent to the surface of Titan and show us this world that is strange and yet in many ways similar to our own.

Titan!

NASA Astrophysics Data System (ADS)

Matson, Dennis L.

2010-05-01

Cassini-Huygens achieved Saturnian orbit on July 1, 2004. The first order of business was the safe delivery of the Huygens atmospheric probe to Titan that took place on January 14, 2005. Huygens descended under parachute obtaining observations all the way down to a safe landing. It revealed Titan for the first time. Stunning are the similarities between Titan and the Earth. Viewing the lakes and seas, the fluvial terrain, the sand dunes and other features through the hazy, nitrogen atmosphere, brings to mind the geological processes that created analogous features on the Earth. On Titan frozen water plays the geological role of rock; liquid methane takes the role of terrestrial water. The atmospheres of both Earth and Titan are predominately nitrogen gas. Titan's atmosphere contains 1.5% methane and no oxygen. The surface pressure on Titan is 1.5 times the Earth's. There are aerosol layers and clouds that come and go. Now, as Saturn proceeds along its solar orbit, the seasons are changing. The effects upon the transport of methane are starting to be seen. A large lake in the South Polar Region seems to be filling more as winter onsets. Will the size and number of the lakes in the South grow during winter? Will the northern lakes and seas diminish or dry up as northern summer progresses? How will the atmospheric circulation change? Much work remains not only for Cassini but also for future missions. Titan has many different environments to explore. These require more capable instruments and in situ probes. This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration.

Earth-Mars transfers through Moon Distant Retrograde Orbits

NASA Astrophysics Data System (ADS)

Conte, Davide; Di Carlo, Marilena; Ho, Koki; Spencer, David B.; Vasile, Massimiliano

2018-02-01

This paper focuses on the trajectory design which is relevant for missions that would exploit the use of asteroid mining in stable cis-lunar orbits to facilitate deep space missions, specifically human Mars exploration. Assuming that a refueling "gas station" is present at a given lunar Distant Retrograde Orbit (DRO), ways of departing from the Earth to Mars via that DRO are analyzed. Thus, the analysis and results presented in this paper add a new cis-lunar departure orbit for Earth-Mars missions. Porkchop plots depicting the required C3 at launch, v∞ at arrival, Time of Flight (TOF), and total Δ V for various DRO departure and Mars arrival dates are created and compared with results obtained for low Δ V Low Earth Orbit (LEO) to Mars trajectories. The results show that propellant-optimal trajectories from LEO to Mars through a DRO have higher overall mission Δ V due to the additional stop at the DRO. However, they have lower Initial Mass in LEO (IMLEO) and thus lower gear ratio as well as lower TOF than direct LEO to Mars transfers. This results in a lower overall spacecraft dry mass that needs to be launched into space from Earth's surface.

Calibration Image of Earth by Mars Color Imager

NASA Image and Video Library

2005-08-22

Three days after the Mars Reconnaissance Orbiter Aug. 12, 2005, launch, the NASA spacecraft was pointed toward Earth and the Mars Color Imager camera was powered up to acquire a suite of color and ultraviolet images of Earth and the Moon.

A new upper limit to the field-aligned potential near Titan.

PubMed

Coates, Andrew J; Wellbrock, Anne; Waite, J Hunter; Jones, Geraint H

2015-06-28

Neutral particles dominate regions of the Saturn magnetosphere and locations near several of Saturn's moons. Sunlight ionizes neutrals, producing photoelectrons with characteristic energy spectra. The Cassini plasma spectrometer electron spectrometer has detected photoelectrons throughout these regions, where photoelectrons may be used as tracers of magnetic field morphology. They also enhance plasma escape by setting up an ambipolar electric field, since the relatively energetic electrons move easily along the magnetic field. A similar mechanism is seen in the Earth's polar wind and at Mars and Venus. Here we present a new analysis of Titan photoelectron data, comparing spectra measured in the sunlit ionosphere at ~1.4 Titan radii ( R T ) and at up to 6.8 R T away. This results in an upper limit on the potential of 2.95 V along magnetic field lines associated with Titan at up to 6.8 R T , which is comparable to some similar estimates for photoelectrons seen in Earth's magnetosphere.

A new upper limit to the field‐aligned potential near Titan

PubMed Central

Wellbrock, Anne; Waite, J. Hunter; Jones, Geraint H.

2015-01-01

Abstract Neutral particles dominate regions of the Saturn magnetosphere and locations near several of Saturn's moons. Sunlight ionizes neutrals, producing photoelectrons with characteristic energy spectra. The Cassini plasma spectrometer electron spectrometer has detected photoelectrons throughout these regions, where photoelectrons may be used as tracers of magnetic field morphology. They also enhance plasma escape by setting up an ambipolar electric field, since the relatively energetic electrons move easily along the magnetic field. A similar mechanism is seen in the Earth's polar wind and at Mars and Venus. Here we present a new analysis of Titan photoelectron data, comparing spectra measured in the sunlit ionosphere at ~1.4 Titan radii (R T) and at up to 6.8 R T away. This results in an upper limit on the potential of 2.95 V along magnetic field lines associated with Titan at up to 6.8 R T, which is comparable to some similar estimates for photoelectrons seen in Earth's magnetosphere. PMID:27609997

A bibliography of dunes: Earth, Mars, and Venus

NASA Technical Reports Server (NTRS)

Lancaster, N.

1988-01-01

Dunes are important depositional landforms and sedimentary environments on Earth and Mars, and may be important on Venus. The similarity of dune forms on Earth and Mars, together with the dynamic similarity of aeolian processes on the terrestrial planets indicates that it is appropriate to interpret dune forms and processes on Mars and Venus by using analog studies. However, the literature on dune studies is large and scattered. The aim of this bibliography is to assist investigators by providing a literature resource on techniques which have proved successful in elucidating dune characteristics and processes on Earth, Mars, and Venus. This bibliography documents the many investigations of dunes undertaken in the last century. It concentrates on studies of inland dunes in both hot and cold desert regions on Earth and includes investigations of coastal dunes only if they discuss matters of general significance for dune sediments, processes, or morphology.

Titan: a laboratory for prebiological organic chemistry

NASA Technical Reports Server (NTRS)

Sagan, C.; Thompson, W. R.; Khare, B. N.

1992-01-01

When we examine the atmospheres of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune), the satellites in the outer solar system, comets, and even--through microwave and infrared spectroscopy--the cold dilute gas and grains between the stars, we find a rich organic chemistry, presumably abiological, not only in most of the solar system but throughout the Milky Way galaxy. In part because the composition and surface pressure of the Earth's atmosphere 4 x 10(9) years ago are unknown, laboratory experiments on prebiological organic chemistry are at best suggestive; but we can test our understanding by looking more closely at the observed extraterrestrial organic chemistry. The present Account is restricted to atmospheric organic chemistry, primarily on the large moon of Saturn. Titan is a test of our understanding of the organic chemistry of planetary atmospheres. Its atmospheric bulk composition (N2/CH4) is intermediate between the highly reducing (H2/He/CH4/NH3/H2O) atmospheres of the Jovian planets and the more oxidized (N2/CO2/H2O) atmospheres of the terrestrial planets Mars and Venus. It has long been recognized that Titan's organic chemistry may have some relevance to the events that led to the origin of life on Earth. But with Titan surface temperatures approximately equal to 94 K and pressures approximately equal to 1.6 bar, the oceans of the early Earth have no ready analogue on Titan. Nevertheless, tectonic events in the water ice-rich interior or impact melting and slow re-freezing may lead to an episodic availability of liquid water. Indeed, the latter process is the equivalent of a approximately 10(3)-year-duration shallow aqueous sea over the entire surface of Titan.

Effect of Earth and Mars departure delays on human missions to Mars

NASA Technical Reports Server (NTRS)

Desai, Prasun N.; Tartabini, Paul V.

1993-01-01

This study determines the impact on the initial mass in low-Earth orbit (IMLEO) for delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep space maneuver (DSM) is attempted to alleviate the IMLEO penalties. Three different classes of missions are analyzed using chemical and nuclear thermal propulsion systems in the 2000-2025 time-frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction class missions have the highest IMLEO penalties, upwards of 432.4 mt and 1977.3 mt, respectively. Conjunction class missions, on the other hand, tend to be insensitive to Mars and Earth delays having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties as compared to chemical propulsion. The use of a DSM is found not to have a significant impact on reducing the IMLEO penalties. Through this investigation, the effect of off-nominal departure conditions on the overall mission (i.e., IMLEO) can be gained, enabling mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design process of a Mars transfer vehicle.

Visualizing Mars data and imagery with Google Earth

NASA Astrophysics Data System (ADS)

Beyer, R. A.; Broxton, M.; Gorelick, N.; Hancher, M.; Lundy, M.; Kolb, E.; Moratto, Z.; Nefian, A.; Scharff, T.; Weiss-Malik, M.

2009-12-01

There is a vast store of planetary geospatial data that has been collected by NASA but is difficult to access and visualize. Virtual globes have revolutionized the way we visualize and understand the Earth, but other planetary bodies including Mars and the Moon can be visualized in similar ways. Extraterrestrial virtual globes are poised to revolutionize planetary science, bring an exciting new dimension to science education, and allow ordinary users to explore imagery being sent back to Earth by planetary science satellites. The original Google Mars Web site allowed users to view base maps of Mars via the Web, but it did not have the full features of the 3D Google Earth client. We have previously demonstrated the use of Google Earth to display Mars imagery, but now with the launch of Mars in Google Earth, there is a base set of Mars data available for anyone to work from and add to. There are a variety of global maps to choose from and display. The Terrain layer has the MOLA gridded data topography, and where available, HRSC terrain models are mosaicked into the topography. In some locations there is also meter-scale terrain derived from HiRISE stereo imagery. There is rich information in the form of the IAU nomenclature database, data for the rovers and landers on the surface, and a Spacecraft Imagery layer which contains the image outlines for all HiRISE, CTX, CRISM, HRSC, and MOC image data released to the PDS and links back to their science data. There are also features like the Traveler's Guide to Mars, Historic Maps, Guided Tours, as well as the 'Live from Mars' feature, which shows the orbital tracks of both the Mars Odyssey and Mars Reconnaissance Orbiter for a few days in the recent past. It shows where they have acquired imagery, and also some preview image data. These capabilities have obvious public outreach and education benefits, but the potential benefits of allowing planetary scientists to rapidly explore these large and varied data collections�

Interplanetary Mission Design Handbook: Earth-to-Mars Mission Opportunities and Mars-to-Earth Return Opportunities 2009-2024

NASA Technical Reports Server (NTRS)

George, L. E.; Kos, L. D.

1998-01-01

This paper provides information for trajectory designers and mission planners to determine Earth-Mars and Mars-Earth mission opportunities for the years 2009-2024. These studies were performed in support of a human Mars mission scenario that will consist of two cargo launches followed by a piloted mission during the next opportunity approximately 2 years later. "Porkchop" plots defining all of these mission opportunities are provided which include departure energy, departure excess speed, departure declination arrival excess speed, and arrival declinations for the mission space surrounding each opportunity. These plots are intended to be directly applicable for the human Mars mission scenario described briefly herein. In addition, specific trajectories and several alternate trajectories are recommended for each cargo and piloted opportunity. Finally, additional studies were performed to evaluate the effect of various thrust-to-weight ratios on gravity losses and total time-of-flight tradeoff, and the resultant propellant savings and are briefly summarized.

Size-Selective Modes of Aeolian Transport on Earth and Mars

NASA Astrophysics Data System (ADS)

Swann, C.; Ewing, R. C.; Sherman, D. J.; McLean, C. J.

2016-12-01

Aeolian sand transport is a dominant driver of surface change and dust emission on Mars. Estimates of aeolian sand transport on Earth and Mars rely on terrestrial transport models that do not differentiate between transport modes (e.g., creep vs. saltation), which limits estimates of the critical threshold for transport and the total sand flux during a transport event. A gap remains in understanding how the different modes contribute to the total sand flux. Experiments conducted at the MARtian Surface WInd Tunnel separated modes of transport for uniform and mixed grain size surfaces at Earth and Martian atmospheric pressures. Crushed walnut shells with a density of 1.0 gm/cm3 were used. Experiments resolved grain size distributions for creeping and saltating grains over 3 uniform surfaces, U1, U2, and U3, with median grain sizes of 308 µm, 721 µm, and 1294 µm, and a mixed grain size surface, M1, with median grain sizes of 519 µm. A mesh trap located 5 cm above the test bed and a surface creep trap were deployed to capture particles moving as saltation and creep. Grains that entered the creep trap at angles ≥ 75° were categorized as moving in creep mode only. Only U1 and M1 surfaces captured enough surface creep at both Earth and Mars pressure for statistically significant grain size analysis. Our experiments show that size selective transport differs between Earth and Mars conditions. The median grain size of particles moving in creep for both uniform and mixed surfaces are larger under Earth conditions. (U1Earth = 385 µm vs. U1Mars = 355 µm; M1Earth = 762 vs. M1Mars = 697 µm ). However, particles moving in saltation were larger under Mars conditions (U1Earth = 282 µm; U1Mars = 309 µm; M1Earth = 347 µm; M1Mars = 454 µm ). Similar to terrestrial experiments, the median size of surface creep is larger than the median grain size of saltation. Median sizes of U1, U2, U3 at Mars conditions for creep was 355 µm, 774 µm and 1574 µm. Saltation at Mars

Water inventories on Earth and Mars: Clues to atmosphere formation

NASA Technical Reports Server (NTRS)

Carr, M. H.

1992-01-01

Water is distributed differently on Earth and on Mars and the differences may have implications for the accretion of the two planets and the formation of their atmospheres. The Earth's mantle appears to contain at least several times the water content of the Martian mantle even accounting for differences in plate tectonics. One explanation is that the Earth's surface melted during accretion, as a result of development of a steam atmosphere, thereby allowing impact-devolitalized water at the surface to dissolve into the Earth's interior. In contrast, because of Mars' smaller size and greater distance from the Sun, the Martian surface may not have melted, so that the devolatilized water could not dissolve into the surface. A second possibility is suggested by the siderophile elements in the Earth's mantle, which indicates the Earth acquired a volatile-rich veneer after the core formed. Mars may have acquired a late volatile-rich veneer, but it did not get folded into the interior as with the Earth, but instead remained as a water rich veneer. This perception of Mars with a wet surface but dry interior is consistent with our knowledge of Mars' geologic history.

Titan's Exotic Weather

NASA Astrophysics Data System (ADS)

Griffith, Caitlin A.

2006-09-01

Images of Titan, taken during the joint NASA and European Space Agency Cassini-Huygens mission, invoke a feeling of familiarity: washes wind downhill to damp lakebeds; massive cumuli form and quickly dissipate, suggestive of rain; and dark oval regions resemble lakes. These features arise from Titan's unique similarity with Earth: both cycle liquid between their surfaces and atmospheres, but in Titan's cool atmosphere it is methane that exists as a gas, liquid, and ice. While Titan enticingly resembles Earth, its atmosphere is 10 times thicker, so that its radiative time constant near the surface exceeds a Titan year, and prohibits large thermal gradients and seasonal surface temperature variations exceeding 3K. Titan also lacks oceans - central to Earth's climate - and instead stores much of its condensible in its atmosphere. As a result, Titan's weather differs remarkably from Earth's. Evidence for this difference appears in the location of Titan's large clouds, which frequent a narrow band at 40S latitude and a region within 30 latitude of the S. Pole. Ground-based and Cassini observations, combined with thermodynamic considerations, indicate that we are seeing large convective cloud systems. Detailed cloud models and general circulation models further suggest that these are severe rain storms, which will migrate with the change in season. Outside these migrating "gypsy" cloud bands, the atmosphere appears to be calm, humid and thus frequented by thin stratiform clouds. An intriguingly alien environment is predicted. Yet, the combined effects of Titan's patchy wet surface, atmospheric tides, possible ice volcanoes, and detailed seasonal variations remain unclear as we have witnessed only one season so far. This talk will review observations of Titan's lower atmosphere and modeling efforts to explain the observations, and explore the questions that still elude us.

Curiosity Mars Rover First Image of Earth and Earth Moon

NASA Image and Video Library

2014-02-06

The two bodies in this portion of an evening-sky view by NASA Mars rover Curiosity are Earth and Earth moon. The rover Mast Camera Mastcam imaged them in the twilight sky of Curiosity 529th Martian day, or sol Jan. 31, 2014.

MGS Mars Orbiter Laser Altimeter (MOLA) - Mars/Earth Relief Comparison

NASA Technical Reports Server (NTRS)

1997-01-01

Comparison of the cross-sectional relief of the deepest portion of the Grand Canyon (Arizona) on Earth versus a Mars Orbiter Laser Altimeter (MOLA) view of a common type of chasm on Mars in the western Elysium region. The MOLA profile was collected during the Mars Global Surveyor Capture Orbit Calibration Pass on September 15, 1997. The Grand Canyon topography is shown as a trace with a measurement every 295 feet (90 meters) along track, while that from MOLA reflects measurements about every 970 feet (400 meters) along track. The slopes of the steep inner canyon wall of the Martian feature exceed the angle of repose, suggesting relative youth and the potential for landslides. The inner wall slopes of the Grand Canyon are less than those of the Martian chasm, reflecting the long period of erosion necessary to form its mile-deep character on Earth.

Libration-point staging concepts for Earth-Mars transportation

NASA Technical Reports Server (NTRS)

Farquhar, Robert; Dunham, David

1986-01-01

The use of libration points as transfer nodes for an Earth-Mars transportation system is briefly described. It is assumed that a reusable Interplanetary Shuttle Vehicle (ISV) operates between the libration point and Mars orbit. Propellant for the round-trip journey to Mars and other supplies would be carried from low Earth orbit (LEO) to the ISV by additional shuttle vehicles. Different types of trajectories between LEO and libration points are presented, and approximate delta-V estimates for these transfers are given. The possible use of lunar gravity-assist maneuvers is also discussed.

Nitrogen isotope ratio and its evolution on Titan

NASA Astrophysics Data System (ADS)

Krasnopolsky, V.

2017-09-01

14N/15N ratios in the Sun, Jupiter, comets, and the inner planets indicate that Earth, Venus, and Mars got their nitrogen as N2 gas and NH3 ice in proportion 3 : 1. An alternative explanation is that planetesimals were another reservoir of N with 14N/15N = 270. 14N/15N = 168 in N2 and 60 in HCN on Titan, and the great difference is explained by strong enrichment in 15N by a factor of 8 in predissociation of N2 at 80-100 nm (Liang et al. 2007) and no fractionation in other 12 processes that form N. The calculated 14N/15N = 57 in nitriles, in perfect agreement with the observations. Modeling of nitrogen isotope fractionation by formation of nitriles and sputtering through the history of Titan with the much greater solar EUV and wind in the earlier epochs supports ammonia similar to that in comets as a source of nitrogen on Titan.

Circulating transportation orbits between earth and Mars

NASA Technical Reports Server (NTRS)

Friedlander, A. L.; Niehoff, J. C.; Byrnes, D. V.; Longuski, J. M.

1986-01-01

This paper describes the basic characteristics of circulating (cyclical) orbit design as applied to round-trip transportation of crew and materials between earth and Mars in support of a sustained manned Mars Surface Base. The two main types of nonstopover circulating trajectories are the socalled VISIT orbits and the Up/Down Escalator orbits. Access to the large transportation facilities placed in these orbits is by way of taxi vehicles using hyperbolic rendezvous techniques during the successive encounters with earth and Mars. Specific examples of real trajectory data are presented in explanation of flight times, encounter frequency, hyperbolic velocities, closest approach distances, and Delta V maneuver requirements in both interplanetary and planetocentric space.

Boots on Mars: Earth Independent Human Exploration of Mars

NASA Technical Reports Server (NTRS)

Burnett, Josephine; Gill, Tracy R.; Ellis, Kim Gina

2017-01-01

This package is for the conduct of a workshop during the International Space University Space Studies Program in the summer of 2017 being held in Cork, Ireland. It gives publicly available information on NASA and international plans to move beyond low Earth orbit to Mars and discusses challenges and capabilities. This information will provide the participants a basic level of insight to develop a response on their perceived obstacles to a future vision of humans on Mars.

Earth and Moon as viewed from Mars

NASA Image and Video Library

2003-05-22

This is the first image of Earth ever taken from another planet that actually shows our home as a planetary disk. Because Earth and the Moon are closer to the Sun than Mars, they exhibit phases, just as the Moon, Venus, & Mercury do when viewed from Earth

Could Martian Strawberries Be? -- Prebiotic Chemical Evolution on an Early Wet Mars

NASA Astrophysics Data System (ADS)

Lerman, L.

2005-03-01

The universality of chemical physics dictates the ubiquity of bubbles, aerosols, and droplets on planets with water and simple amphiphiles. Their ability to functionally support prebiotic chemical evolution seems critical: on the early Earth and Mars, and quite likely for Titan and Europa.

The Coolest Landscape on Mars or Earth

NASA Image and Video Library

2016-12-07

Many Martian landscapes contain features that are familiar to ones we find on Earth, like river valleys, cliffs, glaciers and volcanos. However, Mars has an exotic side too, with landscapes that are alien to Earthlings. This image shows one of these exotic locales at the South Pole. The polar cap is made from carbon dioxide (dry ice), which does not occur naturally on the Earth. The circular pits are holes in this dry ice layer that expand by a few meters each Martian year. New dry ice is constantly being added to this landscape by freezing directly out of the carbon dioxide atmosphere or falling as snow. Freezing out the atmosphere like this limits how cold the surface can get to the frost point at -130 degrees Celsius (-200 F). Nowhere on Mars can ever get any colder this, making this this coolest landscape on Earth and Mars combined. http://photojournal.jpl.nasa.gov/catalog/PIA21216

21st century early mission concepts for Mars delivery and earth return

NASA Technical Reports Server (NTRS)

Cruz, Manuel I.; Ilgen, Marc R.

1990-01-01

In the 21st century, the early missions to Mars will entail unmanned Rover and Sample Return reconnaissance missions to be followed by manned exploration missions. High performance leverage technologies will be required to reach Mars and return to earth. This paper describes the mission concepts currently identified for these early Mars missions. These concepts include requirements and capabilities for Mars and earth aerocapture, Mars surface operations and ascent, and Mars and earth rendezvous. Although the focus is on the unmanned missions, synergism with the manned missions is also discussed.

Mars Earth Return Vehicle (MERV) Propulsion Options

NASA Technical Reports Server (NTRS)

Oleson, Steven R.; McGuire, Melissa L.; Burke, Laura; Fincannon, James; Warner, Joe; Williams, Glenn; Parkey, Thomas; Colozza, Tony; Fittje, Jim; Martini, Mike;

Earth and Moon as Seen from Mars

NASA Image and Video Library

2008-03-03

The High Resolution Imaging Science Experiment HiRISE camera would make a great backyard telescope for viewing Mars, and we can also use it at Mars to view other planets. This is an image of Earth and the moon, acquired on October 3, 2007.

Titan is to Earth's Hydrological Cycle what Venus is to its Greenhouse Effect

NASA Astrophysics Data System (ADS)

Lorenz, R. D.

2012-06-01

Titan serves as an extreme extrapolation of Earth's possible present trend toward more violent rainstorms interspersed by long droughts, much as Venus has acted as a bogeyman to illustrate the perils of enhanced greenhouse warming.

Radiation Measurements During Trip From Earth to Mars

NASA Image and Video Library

2013-05-30

This graphic shows the level of natural radiation detected by the Radiation Assessment Detector shielded inside NASA Mars Science Laboratory on the trip from Earth to Mars from December 2011 to July 2012.

Earth and Moon as viewed from Mars

NASA Technical Reports Server (NTRS)

2003-01-01

MGS MOC Release No. MOC2-368, 22 May 2003

[figure removed for brevity, see original site] Globe diagram illustrates the Earth's orientation as viewed from Mars (North and South America were in view).

Earth/Moon: This is the first image of Earth ever taken from another planet that actually shows our home as a planetary disk. Because Earth and the Moon are closer to the Sun than Mars, they exhibit phases, just as the Moon, Venus, and Mercury do when viewed from Earth. As seen from Mars by MGS on 8 May 2003 at 13:00 GMT (6:00 AM PDT), Earth and the Moon appeared in the evening sky. The MOC Earth/Moon image has been specially processed to allow both Earth (with an apparent magnitude of -2.5) and the much darker Moon (with an apparent magnitude of +0.9) to be visible together. The bright area at the top of the image of Earth is cloud cover over central and eastern North America. Below that, a darker area includes Central America and the Gulf of Mexico. The bright feature near the center-right of the crescent Earth consists of clouds over northern South America. The image also shows the Earth-facing hemisphere of the Moon, since the Moon was on the far side of Earth as viewed from Mars. The slightly lighter tone of the lower portion of the image of the Moon results from the large and conspicuous ray system associated with the crater Tycho.

A note about the coloring process: The MGS MOC high resolution camera only takes grayscale (black-and-white) images. To 'colorize' the image, a Mariner 10 Earth/Moon image taken in 1973 was used to color the MOC Earth and Moon picture. The procedure used was as follows: the Mariner 10 image was converted from 24-bit color to 8-bit color using a JPEG to GIF conversion program. The 8-bit color image was converted to 8-bit grayscale and an associated lookup table mapping each gray value of the image to a red-green-blue color triplet (RGB). Each color triplet was root-sum-squared (RSS), and sorted in increasing RSS

Titan's Radioactive Haze : Production and Fate of Radiocarbon On Titan

NASA Astrophysics Data System (ADS)

Lorenz, R. D.; Jull, A. J. T.; Swindle, T. D.; Lunine, J. I.

Just as cosmic rays interact with nitrogen atoms in the atmosphere of Earth to gener- ate radiocarbon (14C), the same process should occur in Titan`s nitrogen-rich atmo- sphere. Titan`s atmosphere is thick enough that cosmic ray flux, rather than nitrogen column depth, limits the production of 14 C. Absence of a strong magnetic field and the increased distance from the sun suggest production rates of 9 atom/cm2/s, approx- imately 4 times higher than Earth. On Earth the carbon is rapidly oxidised into CO2. The fate and detectability of 14C on Titan depends on the chemical species into which it is incorporated in Titan's reducing atmosphere : as methane it would be hopelessly diluted even in only the atmosphere (ignoring the other, much more massive carbon reservoirs likely to be present on Titan, like hydrocarbon lakes.) However, in the more likely case that the 14C attaches to the haze that rains out onto the surface (as tholin, HCN or acetylene and their polymers - a much smaller carbon reservoir) , haze in the atmosphere or recently deposited on the surface would therefore be quite intrinsically radioactive. Such activity may modify the haze electrical charging and hence its coag- ulation. Measurements with compact instrumentation on future in-situ missions could place useful constraints on the mass deposition rates of photochemical material on the surface and identify locations where surface deposits of such material are `freshest`.

Calibration View of Earth and the Moon by Mars Color Imager

NASA Technical Reports Server (NTRS)

2005-01-01

Three days after the Mars Reconnaissance Orbiter's Aug. 12, 2005, launch, the spacecraft was pointed toward Earth and the Mars Color Imager camera was powered up to acquire a suite of images of Earth and the Moon. When it gets to Mars, the Mars Color Imager's main objective will be to obtain daily global color and ultraviolet images of the planet to observe martian meteorology by documenting the occurrence of dust storms, clouds, and ozone. This camera will also observe how the martian surface changes over time, including changes in frost patterns and surface brightness caused by dust storms and dust devils.

The purpose of acquiring an image of Earth and the Moon just three days after launch was to help the Mars Color Imager science team obtain a measure, in space, of the instrument's sensitivity, as well as to check that no contamination occurred on the camera during launch. Prior to launch, the team determined that, three days out from Earth, the planet would only be about 4.77 pixels across, and the Moon would be less than one pixel in size, as seen from the Mars Color Imager's wide-angle perspective. If the team waited any longer than three days to test the camera's performance in space, Earth would be too small to obtain meaningful results.

The Earth and Moon images were acquired by turning Mars Reconnaissance Orbiter toward Earth, then slewing the spacecraft so that the Earth and Moon would pass before each of the five color and two ultraviolet filters of the Mars Color Imager. The distance to the Moon was about 1,440,000 kilometers (about 895,000 miles); the range to Earth was about 1,170,000 kilometers (about 727,000 miles).

This view combines a sequence of frames showing the passage of Earth and the Moon across the field of view of a single color band of the Mars Color Imager. As the spacecraft slewed to view the two objects, they passed through the camera's field of view. Earth has been saturated white in this image so that both Earth

Numerical Prediction of Radiation Measurements Taken in the X2 Facility for Mars and Titan Gas Mixtures

NASA Technical Reports Server (NTRS)

Palmer, Grant; Prabhu, Dinesh; Brandis, Aaron; McIntyre, Timothy J.

2011-01-01

Thermochemical relaxation behind a normal shock in Mars and Titan gas mixtures is simulated using a CFD solver, DPLR, for a hemisphere of 1 m radius; the thermochemical relaxation along the stagnation streamline is considered equivalent to the flow behind a normal shock. Flow simulations are performed for a Titan gas mixture (98% N2, 2% CH4 by volume) for shock speeds of 5.7 and 7.6 km/s and pressures ranging from 20 to 1000 Pa, and a Mars gas mixture (96% CO2, and 4% N2 by volume) for a shock speed of 8.6 km/s and freestream pressure of 13 Pa. For each case, the temperatures and number densities of chemical species obtained from the CFD flow predictions are used as an input to a line-by-line radiation code, NEQAIR. The NEQAIR code is then used to compute the spatial distribution of volumetric radiance starting from the shock front to the point where thermochemical equilibrium is nominally established. Computations of volumetric spectral radiance assume Boltzmann distributions over radiatively linked electronic states of atoms and molecules. The results of these simulations are compared against experimental data acquired in the X2 facility at the University of Queensland, Australia. The experimental measurements were taken over a spectral range of 310-450 nm where the dominant contributor to radiation is the CN violet band system. In almost all cases, the present approach of computing the spatial variation of post-shock volumetric radiance by applying NEQAIR along a stagnation line computed using a high-fidelity flow solver with good spatial resolution of the relaxation zone is shown to replicate trends in measured relaxation of radiance for both Mars and Titan gas mixtures.

Titan AVIATR - Aerial Vehicle for In Situ and Airborne Titan Reconnaissance

NASA Astrophysics Data System (ADS)

Kattenhorn, Simon A.; Barnes, J. W.; McKay, C. P.; Lemke, L.; Beyer, R. A.; Radebaugh, J.; Adamkovics, M.; Atkinson, D. H.; Burr, D. M.; Colaprete, T.; Foch, R.; Le Mouélic, S.; Merrison, J.; Mitchell, J.; Rodriguez, S.; Schaller, E.

2010-10-01

Titan AVIATR - Aerial Vehicle for In Situ and Airborne Titan Reconnaissance - is a small (120 kg), nuclear-powered Titan airplane in the Discovery/New Frontiers class based on the concept of Lemke (2008 IPPW). The scientific goals of the mission are designed around the unique flexibility offered by an airborne platform: to explore Titan's diversity of surface landforms, processes, and compositions, as well as to study and measure the atmospheric circulation, aerosols, and humidity. AVIATR would address and surpass many of the science goals of hot-air balloons in Titan flagship studies. The strawman instrument payload is narrowly focused on the stated scientific objectives. The optical remote sensing suite comprises three instruments - an off-nadir high-resolution 2-micron camera, a horizon-looking 5-micron imager, and a 1-6 micron pushbroom near-infrared spectrometer. The in situ instruments include atmospheric structure, a methane humidity sensor, and a raindrop detector. An airplane has operational advantages over a balloon. Its piloted nature allows a go-to capability to image locations of interest in real time, thereby allowing for directed exploration of many features of primary geologic interest: Titan's sand dunes, mountains, craters, channels, and lakes. Subsequent imaging can capture changes in these features during the primary mission. AVIATR can fly predesigned routes, building up large context mosaics of areas of interest before swooping down to low altitude to acquire high-resolution images at 30-cm spatial sampling, similar to that of HiRISE at Mars. The elevation flexibility of the airplane allows us to acquire atmospheric profiles as a function of altitude at any desired location. Although limited by the direct-to-Earth downlink bandwidth, the total scientific data return from AVIATR will be >40 times that returned from Huygens. To maximize the science per bit, novel data storage and downlink techniques will be employed, including lossy compression

Earth rocks on Mars: Must planetary quarantine be rethought

NASA Technical Reports Server (NTRS)

Melosh, H. J.

1988-01-01

Recent geochemical, isotopic, and rare gas studies suggest that eight SNC meteorites originated on the planet Mars. Since Martian rocks are found on Earth, consideration is being given to finding Earth rocks on Mars. Detailed consideration of the mechanism by which these meteorites were lofted into space strongly suggest that the process of stress-wave spallation near a large impact with, perhaps, an assist from vapor plume expansion, is the fundamental process by which lightly-shocked rock debris is ejected into interplanetary space. The theory of spall ejection was used to examine the mass and velocity of material ejected from the near vicinity of an impact. It seems likely that the half-dozen largest impact events on Earth would have ejected considerable masses of near surface rocks into interplanetary space. No computations were performed to indicate how long Earth ejecta would take to reach Mars.

Bright Evening Star Seen from Mars is Earth

NASA Image and Video Library

2014-02-06

This view of the twilight sky and Martian horizon taken by NASA Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

Ground Ice on Earth and Mars

NASA Astrophysics Data System (ADS)

Martineau, N.; Pollard, W.

2003-12-01

On Mars, just like on Earth, water exists in various phases and participates in a broad range of key processes. Even though present surface conditions on Mars, as defined by climate and atmospheric pressure, prevents the occurrence of liquid water on the surface, there is strong evidence suggesting that water was an important land-forming agent in the past (Carr 1996). This naturally raises the question, "where has the water gone?" Surficial water reservoirs that are directly observable on Mars include seasonal water ice deposits and permanent water ice deposits at the polar caps (Kieffer and Zent 1992, Clifford et al. 2000). Due to the existence of permafrost landform systems, such as polygonal ground, rootless cones, and frost mounts, it also has been speculated that much more water may be preserved as ground ice (Lucchitta 1981, Squyres and Carr 1986, Lanagan et al. 2001). Nevertheless, comparison of the likely patterns of ground ice on Mars with terrestrial equivalents has been limited. Fortunately, NASA's 2001 Odyssey data lends support to this hypothesis by identifying significant shallow ice-rich sediments by means of flux characteristics of neutrons, and gamma radiation, and spatial correlations to regions where it has been predicted that subsurface ice is stable (Bell 2002). The ice contents and stratigraphic distribution of the subsurface sediments on Mars, derived by the Odyssey Science Team, is not unlike the upper layers of terrestrial permafrost. Terrestrial polar environments, in particular the more stable permafrost and ground ice features like ice wedges and massive ground ice, may thus provide valuable clues in the search for water and ice on Mars. Of importance is the fact that these features of the earth's surface do not owe their origin to the seasonal freezing and thawing of the active layer. Under the cold, dry polar climates of the Arctic and Antarctic, periglacial and permafrost landforms have evolved, giving rise to distinctive landscapes

TPS design for aerobraking at Earth and Mars

NASA Astrophysics Data System (ADS)

Williams, S. D.; Gietzel, M. M.; Rochelle, W. C.; Curry, D. M.

1991-08-01

An investigation was made to determine the feasibility of using an aerobrake system for manned and unmanned missions to Mars, and to Earth from Mars and lunar orbits. A preliminary thermal protection system (TPS) was examined for five unmanned small nose radius, straight bi-conic vehicles and a scaled up Aeroassist Flight Experiment (AFE) vehicle aerocapturing at Mars. Analyses were also conducted for the scaled up AFE and an unmanned Sample Return Cannister (SRC) returning from Mars and aerocapturing into Earth orbit. Also analyzed were three different classes of lunar transfer vehicles (LTV's): an expendable scaled up modified Apollo Command Module (CM), a raked cone (modified AFT), and three large nose radius domed cylinders. The LTV's would be used to transport personnel and supplies between Earth and the moon in order to establish a manned base on the lunar surface. The TPS for all vehicles analyzed is shown to have an advantage over an all-propulsive velocity reduction for orbit insertion. Results indicate that TPS weight penalties of less than 28 percent can be achieved using current material technology, and slightly less than the most favorable LTV using advanced material technology.

Earth and Its Moon, as Seen From Mars

NASA Image and Video Library

2017-01-06

This composite image of Earth and its moon, as seen from Mars, combines the best Earth image with the best moon image from four sets of images acquired on Nov. 20, 2016, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Each was separately processed prior to combining them so that the moon is bright enough to see. The moon is much darker than Earth and would barely be visible at the same brightness scale as Earth. The combined view retains the correct sizes and positions of the two bodies relative to each other. HiRISE takes images in three wavelength bands: infrared, red, and blue-green. These are displayed here as red, green, and blue, respectively. This is similar to Landsat images in which vegetation appears red. The reddish feature in the middle of the Earth image is Australia. Southeast Asia appears as the reddish area (due to vegetation) near the top; Antarctica is the bright blob at bottom-left. Other bright areas are clouds. These images were acquired for calibration of HiRISE data, since the spectral reflectance of the Moon's near side is very well known. When the component images were taken, Mars was about 127 million miles (205 million kilometers) from Earth. http://photojournal.jpl.nasa.gov/catalog/PIA21260

Parabolic flights as Earth analogue for surface processes on Mars

NASA Astrophysics Data System (ADS)

Kuhn, Nikolaus J.

2017-04-01

The interpretation of landforms and environmental archives on Mars with regards to habitability and preservation of traces of life requires a quantitative understanding of the processes that shaped them. Commonly, qualitative similarities in sedimentary rocks between Earth and Mars are used as an analogue to reconstruct the environments in which they formed on Mars. However, flow hydraulics and sedimentation differ between Earth and Mars, requiring a recalibration of models describing runoff, erosion, transport and deposition. Simulation of these processes on Earth is limited because gravity cannot be changed and the trade-off between adjusting e.g. fluid or particle density generates other mismatches, such as fluid viscosity. Computational Fluid Dynamics offer an alternative, but would also require a certain degree of calibration or testing. Parabolic flights offer a possibility to amend the shortcomings of these approaches. Parabolas with reduced gravity last up to 30 seconds, which allows the simulation of sedimentation processes and the measurement of flow hydraulics. This study summarizes the experience gathered during four campaigns of parabolic flights, aimed at identifying potential and limitations of their use as an Earth analogue for surface processes on Mars.

Cold Saline Springs in Permafrost on Earth and Mars

NASA Technical Reports Server (NTRS)

Heldann, Jennifer; Toon, Owen B.

2003-01-01

This report summarizes the research results which have emanated from work conducted on Cold Saline Springs in Permafrost on Earth and Mars. Three separate avenues of research including 1) terrestrial field work, 2) analysis of spacecraft data, and 3) numerical modeling were explored to provide a comprehensive investigation of water in the polar desert environments of both Earth and Mars. These investigations and their results are summarized.

Large Ripples on Earth and Mars

NASA Technical Reports Server (NTRS)

Williams, S. H.; Zimbelman, J. R.; Ward, A. W.

2002-01-01

Aeolian ripples on Earth with wavelengths greater than 50 cm have distinctive attributes, that should be helpful in interpreting ripple-like features on Mars. Additional information is contained in the original extended abstract.

Magnetotactic bacteria on Earth and on Mars.

PubMed

McKay, Christopher P; Friedmann, E Imre; Frankel, Richard B; Bazylinski, Dennis A

2003-01-01

Continued interest in the possibility of evidence for life in the ALH84001 Martian meteorite has focused on the magnetite crystals. This review is structured around three related questions: is the magnetite in ALH84001 of biological or non-biological origin, or a mixture of both? does magnetite on Earth provide insight to the plausibility of biogenic magnetite on Mars? could magnetotaxis have developed on Mars? There are credible arguments for both the biological and non-biological origin of the magnetite in ALH84001, and we suggest that more studies of ALH84001, extensive laboratory simulations of non-biological magnetite formation, as well as further studies of magnetotactic bacteria on Earth will be required to further address this question. Magnetite grains produced by bacteria could provide one of the few inorganic traces of past bacterial life on Mars that could be recovered from surface soils and sediments. If there was biogenic magnetite on Mars in sufficient abundance to leave fossil remains in the volcanic rocks of ALH84001, then it is likely that better-preserved magnetite will be found in sedimentary deposits on Mars. Deposits in ancient lakebeds could contain well-preserved chains of magnetite clearly indicating a biogenic origin.

Magnetotactic bacteria on Earth and on Mars

NASA Technical Reports Server (NTRS)

McKay, Christopher P.; Friedmann, E. Imre; Frankel, Richard B.; Bazylinski, Dennis A.

2003-01-01

Continued interest in the possibility of evidence for life in the ALH84001 Martian meteorite has focused on the magnetite crystals. This review is structured around three related questions: is the magnetite in ALH84001 of biological or non-biological origin, or a mixture of both? does magnetite on Earth provide insight to the plausibility of biogenic magnetite on Mars? could magnetotaxis have developed on Mars? There are credible arguments for both the biological and non-biological origin of the magnetite in ALH84001, and we suggest that more studies of ALH84001, extensive laboratory simulations of non-biological magnetite formation, as well as further studies of magnetotactic bacteria on Earth will be required to further address this question. Magnetite grains produced by bacteria could provide one of the few inorganic traces of past bacterial life on Mars that could be recovered from surface soils and sediments. If there was biogenic magnetite on Mars in sufficient abundance to leave fossil remains in the volcanic rocks of ALH84001, then it is likely that better-preserved magnetite will be found in sedimentary deposits on Mars. Deposits in ancient lakebeds could contain well-preserved chains of magnetite clearly indicating a biogenic origin.

Calibration View of Earth and the Moon by Mars Color Imager

NASA Image and Video Library

2005-08-22

Three days after the Mars Reconnaissance Orbiter Aug. 12, 2005, launch, the spacecraft was pointed toward Earth and the Mars Color Imager camera was powered up to acquire a suite of images of Earth and the Moon.

Permanent Habitats in Earth-Sol/Mars-Sol Orbit Positions

NASA Astrophysics Data System (ADS)

Greenspon, J.

Project Outpost is a manned Earth-Sol/Mars-Sol platform that enables permanent occupation in deep space. In order to develop the program elements for this complex mission, Project Outpost will rely primarily on existing/nearterm technology and hardware for the construction of its components. For the purposes of this study, four mission requirements are considered: 1. Outpost - Man's 1st purpose-produced effort of space engineering, in which astructure is developed/constructed in an environment completely alien to currentpractices for EVA guidelines. 2. Newton - a concept study developed at StarGate Research, for the development ofa modified Hohmann personnel orbital transport operating between Earth andMars. Newton would serve as the primary crew delivery apparatus throughrepeatable transfer scheduling for all Earth-Lpoint-Mars activities. Thispermanent "transit system" would establish the foundations for Solar systemcolonization. 3. Cruis - a concept study developed at StarGate Research, for the development of amodified Hohmann cargo orbital transport operating between Earth and Mars.Cruis would serve as the primary equipment delivery apparatus throughrepeatable transfer scheduling for all Earth-Lpoint-Mars activities. Thispermanent "transit system" would establish the foundations for Solar systemcolonization, and 4. Ares/Diana - a more conventional space platform configuration for Lunar andMars orbit is included as a construction baseline. The operations of these assetsare supported, and used for the support, of the outpost. Outpost would be constructed over a 27-year period of launch opportunities into Earth-Sol or Mars-Sol Lagrange orbit (E-S/M-S L1, 4 or 5). The outpost consists of an operations core with a self-contained power generation ability, a docking and maintenance structure, a Scientific Research complex and a Habitation Section. After achieving initial activation, the core will provide the support and energy required to operate the outpost in a 365

Better Preserved on Mars than on Earth

NASA Image and Video Library

2017-02-13

In many ways, Mars bears remarkable similarities to Earth, but in some ways it is drastically different. Scientists often use Earth as an example, or analog, to help us to understand the geologic history of the Red Planet. As we continue to study Mars, it is vitally important to remember in what ways it differs from Earth. One very apparent way, readily observed from orbit, has to do with its preservation of numerous craters of all sizes, which are densest in its Southern hemisphere. Earth has comparatively little preserved craters -- about 1,000 to 1,500 times fewer -- due to very active geologic processes, especially involving water. When it comes to impact craters, there are some things that can no longer be observed on Earth, but can be observed on Mars. This color composite shows one such example. It covers a portion of the northern central peak of an unnamed, 20-kilometer crater that contains abundant fragmental bedrock called "breccia." The geological relationships here suggest that these breccias include ones formed by the host crater, and others formed from numerous impacts in the distant past. Because there are fewer craters preserved on Earth, terrestrial central uplifts do not expose bedrock formed by previous craters. It may have been the case in the past, but such craters were destroyed over geologic time. The map is projected here at a scale of 25 centimeters (9.9 inches) per pixel. [The original image scale is 28 centimeters (11 inches) per pixel (with 1 x 1 binning); objects on the order of 82 centimeters (32 inches) across are resolved.] North is up. http://photojournal.jpl.nasa.gov/catalog/PIA21455

Effects of megascale eruptions on Earth and Mars

USGS Publications Warehouse

Thordarson, T.; Rampino, M.; Keszthelyi, L.P.; Self, S.

2009-01-01

Volcanic features are common on geologically active earthlike planets. Megascale or "super" eruptions involving >1000 Gt of magma have occurred on both Earth and Mars in the geologically recent past, introducing prodigious volumes of ash and volcanic gases into the atmosphere. Here we discuss felsic (explosive) and mafi c (flood lava) supereruptions and their potential atmospheric and environmental effects on both planets. On Earth, felsic supereruptions recur on average about every 100-200,000 years and our present knowledge of the 73.5 ka Toba eruption implies that such events can have the potential to be catastrophic to human civilization. A future eruption of this type may require an unprecedented response from humankind to assure the continuation of civilization as we know it. Mafi c supereruptions have resulted in atmospheric injection of volcanic gases (especially SO2) and may have played a part in punctuating the history of life on Earth. The contrast between the more sustained effects of flood basalt eruptions (decades to centuries) and the near-instantaneous effects of large impacts (months to years) is worthy of more detailed study than has been completed to date. Products of mafi c supereruptions, signifi cantly larger than known from the geologic record on Earth, are well preserved on Mars. The volatile emissions from these eruptions most likely had global dispersal, but the effects may not have been outside what Mars endures even in the absence of volcanic eruptions. This is testament to the extreme variability of the current Martian atmosphere: situations that would be considered catastrophic on Earth are the norm on Mars. ?? 2009 The Geological Society of America.

Solar rotation effects on the thermospheres of Mars and Earth.

PubMed

Forbes, Jeffrey M; Bruinsma, Sean; Lemoine, Frank G

2006-06-02

The responses of Earth's and Mars' thermospheres to the quasi-periodic (27-day) variation of solar flux due to solar rotation were measured contemporaneously, revealing that this response is twice as large for Earth as for Mars. Per typical 20-unit change in 10.7-centimeter radio flux (used as a proxy for extreme ultraviolet flux) reaching each planet, we found temperature changes of 42.0 +/- 8.0 kelvin and 19.2 +/- 3.6 kelvin for Earth and Mars, respectively. Existing data for Venus indicate values of 3.6 +/- 0.6 kelvin. Our observational result constrains comparative planetary thermosphere simulations and may help resolve existing uncertainties in thermal balance processes, particularly CO2 cooling.

Magnetic Fields of the Earth and Mars a Comparison and Discussion

NASA Technical Reports Server (NTRS)

Taylor, Patrick T.

2004-01-01

In several aspects the magnetic fields of the Earth and Mars are similar but also different. In the past both bodies had planetary magnetic fields but while they Earth's field remains today the Martian ceased to operate, at some unknown time in the past, leaving this planet without a main or core field. This fact resulted in the interaction between the solar and interplanetary magnetic fields with the surfaces of these planets being very different. In addition, Mars has large crustal magnetic anomalies, nearly ten times larger than those on the Earth. Since crustal magnetic anomalies are the product of the thickness of the layer of magnetization, both the magnetizing material and the thickness of the layer of this material must be very different on Mars than Earth. Furthermore, the martian anomalies can only be produced by remanent or fossil magnetization, in contrast with the Earth where both induced and remanent magnetization are producing these anomalies. Crustal magnetic anomalies on the Earth are mainly produced by single-domain, irontitanium oxides, in the form of magnetite being the most common on Mars the main magnetic mineral(s) are unknown. The thickness of the martian magnetized layer in comparison with the Earth remains a major area for research. Determining the paleopole position for the Earth has been done by some of the earliest paleomagnetic researchers. Since we do not have oriented martian rock samples determining the paleopoles for Mars has been done by fitting a magnetization vector to individual magnetic anomalies. Several groups have worked on this problem with somewhat differing results.

Multiple origins of linear dunes on Earth and Titan

USGS Publications Warehouse

Rubin, David M.; Hesp, Patrick A.

2009-01-01

Dunes with relatively long and parallel crests are classified as linear dunes. On Earth, they form in at least two environmental settings: where winds of bimodal direction blow across loose sand, and also where single-direction winds blow over sediment that is locally stabilized, be it through vegetation, sediment cohesion or topographic shelter from the winds. Linear dunes have also been identified on Titan, where they are thought to form in loose sand. Here we present evidence that in the Qaidam Basin, China, linear dunes are found downwind of transverse dunes owing to higher cohesiveness in the downwind sediments, which contain larger amounts of salt and mud. We also present a compilation of other settings where sediment stabilization has been reported to produce linear dunes. We suggest that in this dune-forming process, loose sediment accumulates on the dunes and is stabilized; the stable dune then functions as a topographic shelter, which induces the deposition of sediments downwind. We conclude that a model in which Titan's dunes formed similarly in cohesive sediments cannot be ruled out by the existing data.

Not So Titanic

NASA Image and Video Library

2015-07-13

Titan may be a "large" moon -- its name even implies it! -- but it is still dwarfed by its parent planet, Saturn. As it turns out, this is perfectly normal. Although Titan (3200 miles or 5150 kilometers across) is the second-largest moon in the solar system, Saturn is still much bigger, with a diameter almost 23 times larger than Titan's. This disparity between planet and moon is the norm in the solar system. Earth's diameter is "only" 3.7 times our moon's diameter, making our natural satellite something of an oddity. (Another exception to the rule: dwarf planet Pluto's diameter is just under two times that of its moon.) So the question isn't why is Titan so small (relatively speaking), but why is Earth's moon so big? This view looks toward the anti-Saturn hemisphere of Titan. North on Titan is up. The image was taken with the Cassini spacecraft wide-angle camera on April 18, 2015 using a near-infrared spectral filter with a passband centered at 752 nanometers. The view was acquired at a distance of approximately 930,000 miles (1.5 million kilometers) from Titan. Image scale is 56 miles (90 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18326

Terraforming - Making an earth of Mars

NASA Astrophysics Data System (ADS)

McKay, C. P.

1987-12-01

The possibility of creating a habitable environment on Mars via terraforming is discussed. The first step is to determine the amount, distribution, and chemical state of water, carbon dioxide, and nitrogen. The process of warming Mars and altering its atmosphere naturally divides into two steps: in the first step, the planet would be heated by a warm thick carbon dioxide atmosphere, while the second step would be to convert the atmospheric carbon dioxide and soil nitrates to the desired oxygen and nitrogen mixture. It is concluded that life will play a major role in any terraforming of Mars, and that terraforming will be a gradual evolutionary process duplicating the early evolution of life on earth.

Rivers on Titan - numerical modelling of sedimentary structures

NASA Astrophysics Data System (ADS)

Misiura, Katarzyna; Czechowski, Leszek

2016-07-01

On Titan surface we can expect a few different geomorphological forms, e.g. fluvial valley and river channels. In our research we use numerical model of the river to determine the limits of different fluvial parameters that play important roles in evolution of the rivers on Titan and on Earth. We have found that transport of sediments as suspended load is the main way of transport for Titan [1]. We also determined the range of the river's parameters for which braided river is developed rather than meandering river. Similar, parallel simulations for rivers deltas are presented in [2]. Introduction Titan is a very special body in the Solar System. It is the only moon that has dense atmosphere and flowing liquid on its surface. The Cassini-Huygens mission has found on Titan meandering rivers, and indicated processes of erosion, transport of solid material and its sedimentation. This work is aimed to investigate the similarity and differences between these processes on Titan and the Earth. Numerical model The dynamical analysis of the considered rivers is performed using the package CCHE modified for the specific conditions on Titan. The package is based on the Navier-Stokes equations for depth-integrated two dimensional, turbulent flow and three dimensional convection-diffusion equation of sediment transport. For more information about equations see [1]. Parameters of the model We considered our model for a few different parameters of liquid and material transported by a river. For Titan we consider liquid corresponding to a Titan's rain (75% methane, 25% nitrogen), for Earth, of course, the water. Material transported in rivers on Titan is water ice, for Earth - quartz. Other parameters of our model are: inflow discharge, outflow level, grain size of sediments etc. For every calculation performed for Titan's river similar calculations are performed for terrestrial ones. Results and Conclusions The results of our simulation show the differences in behaviour of the

Comments about "Earth 3.0"

NASA Technical Reports Server (NTRS)

Dator, Jim

2006-01-01

Dr. Christopher P. McKay, Planetary Scientist with the Space Science Division of NASA Ames. Chris received his Ph.D. in AstroGeophysics from the University of Colorado in 1982 and has been a research scientist with the NASA Ames Research Center since that time. His current research focuses on the evolution of the solar system and the origin of life. He is also actively involved in planning for future Mars missions including human exploration. Chris been involved in research in Mars-like environments on Earth, traveling to the Antarctic dry valleys, Siberia, the Canadian Arctic, and the Atacama desert to study life in these Mars-like environments. His was a co-I on the Titan Huygen s probe in 2005, the Mars Phoenix lander mission for 2007, and the Mars Science Lander mission for 2009.

Rock Outcrops on Mars and Earth

NASA Image and Video Library

2012-09-27

This set of images compares the Link outcrop of rocks on Mars left with similar rocks seen on Earth right. The Link outcrop shows rounded gravel fragments, or clasts, up to a couple inches few centimeters, within the rock outcrop.

Properties of the moon, Mars, Martian satellites, and near-earth asteroids

NASA Technical Reports Server (NTRS)

Taylor, Jeffrey G.

1989-01-01

Environments and surface properties of the moon, Mars, Martian satellites, and near-earth asteroids are discussed. Topics include gravity, atmospheres, surface properties, surface compositions, seismicity, radiation environment, degradation, use of robotics, and environmental impacts. Gravity fields vary from large fractions of the earth's field such as 1/3 on Mars and 1/6 on the moon to smaller fractions of 0.0004 g on an asteroid 1 km in diameter. Spectral data and the analogy with meteor compositions suggest that near-earth asteroids may contain many resources such as water-rich carbonaceous materials and iron-rich metallic bodies. It is concluded that future mining and materials processing operations from extraterrestrial bodies require an investment now in both (1) missions to the moon, Mars, Phobos, Deimos, and near-earth asteroids and (2) earth-based laboratory research in materials and processing.

Elliptical Chandler pole motions of the Earth and Mars

NASA Astrophysics Data System (ADS)

Barkin, Yury; Ferrandiz, Jose

2010-05-01

In the work the values of the period and eccentricity of Chandler motion of poles of axes of rotation of the Earth and Mars have been determined. The research has been carried out on the basis of developed earlier by authors an intermediate rotary Chandler-Euler motion of the weakly deformable celestial bodies (Barkin, Ferrandiz and Getino, 1996; Barkin, 1998). An influence of a liquid core on Chandler motion of a pole in the given work has not considered. The periods of the specified pole motions make 447.1 d for the Earth and 218.1 d for Mars. In comparison with Euler motions of poles because of elastic properties of planets the Chandler periods are increased accordingly on 142.8 d (about 46.9 %) for the Earth and on 26.2 d (on 13.7 %) for Mars. Values of eccentricities of specified Chandler motions of pole e = √b2 --a2- b (here a both b are smaller and big semi-axes of Chandler ellipse) make 0.09884 for the Earth and 0.3688 for Mars (accordingly, on 21.1 % and 6.2 % more than the appropriate values of eccentricities for models of planets as rigid non-spherical bodies). Axes of an ellipse a also b correspond to the principal equatorial axes of inertia of a planet Ox and Oyfor which the moments of inertia have the smallest valueA and middle value B. The pole of the principal axis of inertia Ox for the Earth is displaced to the west on the angle 14°9285, and the pole of the principal axis of inertia Ox for Mars is displaced to the west on the angle 105°0178 (in the appropriate basic geographical systems of coordinates of the given planets). For ellipticties of Chandler trajectories ɛ = (b- a)-b the values 0.004897 (for the Earth) and 0.07048 (for Mars) have been obtained. The specified values surpass by Euler values of appropriate ellipticties on 46.8 % (in case of the Earth) and on 13.3 % (in the case of Mars). Love number k2describing the elastic properties of planets, were accepted equal 0.30 for the Earth and 0.153 for Mars. Estimations of Chandler periods

Earth as Seen from Mars

NASA Technical Reports Server (NTRS)

2005-01-01

On its 449th martian day, or sol (April 29, 2005), NASA's Mars rover Opportunity woke up approximately an hour after sunset and took this picture of the fading twilight as the stars began to come out. Set against the fading red glow of the sky, the pale dot near the center of the picture is not a star, but a planet -- Earth.

Earth appears elongated because it moved slightly during the 15-second exposures. The faintly blue light from the Earth combines with the reddish sky glow to give the pale white appearance.

The images were taken with Opportunity's panoramic camera, using 440-nanometer, 530-nanometer, and 750-nanometer color filters. In processing on the ground, the images were shifted slightly to compensate for Earth's motion between one image and the next.

Ion Internal Excitation and Co++ 2 Reactivity: Effect On The Titan, Mars and Venus Ionospheric Chemistry

NASA Astrophysics Data System (ADS)

Nicolas, C.; Zabka, J.; Thissen, R.; Dutuit, O.; Alcaraz, C.

In planetary ionospheres, primary molecular and atomic photoions can be produced with substantial electronic and vibrational internal energy. In some cases, this is known to strongly affect both the rate constants and the branching ratio between the reac- tion products. A previous experimental study (Nicolas et al.) made at the Orsay syn- chrotron radiation facility has shown that many endothermic charge transfer reactions which were not considered in the ionospheric chemistry models of Mars, Venus and Earth have to be included because they are driven by electronic excitation of the parent ions. New measurements on two important reactions for Titan and Mars ionospheres, N+ + CH4 and O+ + CO2, will be presented. Branching ratios between products are very different when the parent atomic ions are prepared in their ground states, N+(3P) and O+(4S), or in their first electronic metastable states N+(1D) and O+(2D or P). 2 As the lifetime of these states are long enough, they survive during the mean time be- tween two collisions in the ionospheric conditions. So, the reactions of these excited states must be included in the ionospheric models. Absolute cross section measurements of the reactivity of stable doubly charged molec- ular ions CO++ and their implications for the Martian ionosphere will also be pre- 2 sented. The molecular dication CO++ production by VUV photoionisation and elec- 2 tron impact in the upper ionosphere of Mars is far from being negligible. However, to determine its concentration, it was necessary to evaluate the major loss channels of these ions. For this purpose, we measured the absolute reaction cross section of the sta- ble dications with CO2, the major neutral species of the Mars ionosphere. CO++ ions 2 were produced either by photoionisation or by electron impact, and a reaction cross section of 45 Å2 with 13CO2 was measured. The reaction leads to charge transfer or to collision induced dissociation. These results were integrated in a model

A Rover Concept for Exploring the Surface of Titan

NASA Astrophysics Data System (ADS)

Balint, T. S.; Shirley, J. H.; Schriener, T. M.

2005-12-01

Titan is one of the premier targets for future in-situ exploration in the outer solar system, as unique "pre-biotic" organic chemical processes may be presently occurring at its surface. A mission to the surface of Titan is not as technically difficult as one to Europa; Titan's atmosphere allows for aerobraking descents, the radiation environment is not a mission-critical factor, and the organic materials we want to sample should be widely distributed (and easily accessible). The recent Titan landing by the Huygens Probe has focused considerable scientific interest on this remarkable body, and future missions to Titan are under consideration. We evaluated a Titan Rover mission concept that would have the capability to survive on Titan's surface for a period of 3 terrestrial years. This long mission lifetime is enabled by employing a radioisotope power system (RPS). To minimize costs and use as much flight heritage as possible, we began by assuming that system masses, dimensions, and instrumentation would be comparable to those of the Mars Surface Lander (MSL). We found that a rover configuration with a 110 W (electric) power system and four 1.5 m diameter inflatable wheels could potentially enable traverse distances up to ~500 km, depending on science and mission requirements, surface environments, and the capability of the autonomous navigation system employed. Direct to Earth communication would simplify the mission by removing the need for a relay orbiter. We will describe our strawman instrument payload and rover subsystems. Trades between the potentially available RPS systems (RTG, Advanced RTG, TPV, SRG, Advanced Stirling and Brayton RPSs) will be outlined. While many possible approaches exist for Titan in-situ exploration, the Titan rover concept presented here could provide a scientifically interesting and programmatically affordable solution.

Cassini/Huygens Investigations of Titan's Methane Cycle

NASA Astrophysics Data System (ADS)

Griffith, C. A.; Penteado, P.

2008-12-01

In Titan's atmosphere, the second most abundant constituent, methane, exists as a gas, liquid and solid, and cycles between the atmosphere and surface. Similar to Earth's hydrological cycle, Titan sports clouds, rain, and lakes. Yet, Titan's cycle differs dramatically from its terrestrial counterpart, and reveals the workings of weather in an atmosphere that is ten times thicker than Earth's atmosphere, that is two orders of magnitude less illuminated, and that involves a different condensable. Measurements of Titan's troposphere, where the methane cycle plays out, are limited largely to spectral images of Titan's clouds, several temperature profiles by Voyager, Huygens and Cassini, recent Keck spectra of the surface methane humidity, and one vertical profile of Titan's methane abundance, measured on a summer afternoon in Titan's tropical atmosphere by the Huygens probe. The salient features of Titan's methane cycle are distinctly alien: clouds have predominated the northern and southern polar atmospheres; the one humidity profile precisely matches the profile (of cartoonish simplicity) used in pre-Cassini models, and surface features correlate with latitude. Data of Titan's troposphere are analyzed with thermodynamic and radiative transfer calculations, and synthesized with other studies of Titan's stratosphere and surface, to investigate the workings of Titan's methane cycle. At the end of Cassini's nominal mission, we find that Titan's weather, climate and surface-to-atmosphere exchange of volatiles vastly differs from the manifestation of these processes on Earth, largely as a result of different basic characteristics of these planetary bodies. The talk ends with a comparison between Titan and Earth's tropospheres, their fundamental properties, the energetics of their condensible cycles, their weather and climates. References: Griffith C.A. et al. Titan's Tropical Storms in an Evolving Atmosphere. Ap.J. In Press (2008). Griffith C.A. Storms, Polar Deposits, and

Dunelands of Titan

NASA Image and Video Library

2015-11-02

Saturn's frigid moon Titan has some characteristics that are oddly similar to Earth, but still slightly alien. It has clouds, rain and lakes (made of methane and ethane), a solid surface (made of water ice), and vast dune fields (filled with hydrocarbon sands). The dark, H-shaped area seen here contains two of the dune-filled regions, Fensal (in the north) and Aztlan (to the south). Cassini's cameras have frequently monitored the surface of Titan (3200 miles or 5150 kilometers across) to look for changes in its features over the course of the mission. Any changes would help scientists better understand different phenomena like winds and dune formation on this strangely earth-like moon. For a closer view of Fensal-Aztlan, see PIA07732 . This view looks toward the leading side of Titan. North on Titan is up. The image was taken with the Cassini spacecraft narrow-angle camera on July 25, 2015 using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers. The view was obtained at a distance of approximately 450,000 miles (730,000 kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 32 degrees. Image scale is 3 miles (4 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18341

Earth-type planets (Mercury, Venus, and Mars)

NASA Technical Reports Server (NTRS)

Marov, M. Y.; Davydov, V. D.

1975-01-01

Spacecraft- and Earth-based studies on the physical nature of the planets Mercury, Venus, and Mars are reported. Charts and graphs are presented on planetary surface properties, rotational parameters, atmospheric compositions, and astronomical characteristics.

Mimas...and Titan Beyond

NASA Image and Video Library

2006-01-03

Titan, Saturn largest moon and Mimas in the foreground are seen together in this view from Cassini. Titan gravity is weaker than Earth, so the moon atmosphere is quite extended -- a quality hinted at in this view

A Numerical Study of Micrometeoroids Entering Titan's Atmosphere

NASA Technical Reports Server (NTRS)

Templeton, M.; Kress, M. E.

2011-01-01

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

Hypsometry of Titan

NASA Astrophysics Data System (ADS)

Lorenz, Ralph D.; Turtle, Elizabeth P.; Stiles, Bryan; Le Gall, Alice; Hayes, Alexander; Aharonson, Oded; Wood, Charles A.; Stofan, Ellen; Kirk, Randy

2011-01-01

Cassini RADAR topography data are used to evaluate Titan's hypsometric profile, and to make comparisons with other planetary bodies. Titan's hypsogram is unimodal and strikingly narrow compared with the terrestrial planets. To investigate topographic extremes, a novel variant on the classic hypsogram is introduced, with a logarithmic abscissa to highlight mountainous terrain. In such a plot, the top of the terrestrial hypsogram is quite distinct from those of Mars and Venus due to the 'glacial buzz-saw' that clips terrestrial topography above the snowline. In contrast to the positive skew seen in other hypsograms, with a long tail of positive relief due to mountains, there is an indication (weak, given the limited data for Titan so far) that the Titan hypsogram appears slightly negatively skewed, suggesting a significant population of unfilled depressions. Limited data permit only a simplistic comparison of Titan topography with other icy satellites but we find that the standard deviation of terrain height (albeit at different scales) is similar to those of Ganymede and Europa.

Titan's greenhouse and antigreenhouse effects

NASA Technical Reports Server (NTRS)

Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

1992-01-01

Thermal mechanisms active in Titan's atmosphere are discussed in a brief review of data obtained during the Voyager I flyby in 1980. Particular attention is given to the greenhouse effect (GHE) produced by atmospheric H2, N2, and CH4; this GHE is stronger than that on earth, with CH4 and H2 playing roles similar to those of H2O and CO2 on earth. Also active on Titan is an antigreenhouse effect, in which dark-brown and orange organic aerosols block incoming solar light while allowing IR radiation from the Titan surface to escape. The combination of GHE and anti-GHE leads to a surface temperature about 12 C higher than it would be if Titan had no atmosphere.

Tafoni - A Llink Between Mars and Earth

NASA Astrophysics Data System (ADS)

Iacob, R. H.; Iacob, C. E.

2013-12-01

Remarkable rock erosion structures on the planetary surface, tafoni represent an important instrument for investigating the specific environmental conditions causing such rock formations. From simple cavities to refined honeycomb or other intricate patterns, tafoni are a reflection of the complex interaction between the rock structure and the environmental factors. On the genesis of tafoni, there is no unique breakdown mechanism at work, but a multitude of physical and chemical processes developing over time. However, some of these formation mechanisms are typically predominant. Tafoni can be found on a variety of rock substrates, from sandstone and vesicular lava rocks to granite and basalt, and in a variety of environments, from wet coastal areas to the extreme dry zones of hot deserts, high plateaus or frozen lands of Antarctica. During various NASA missions, tafoni were also identified on rock formations on Mars. Comparative study of the environmental conditions leading to the formation of tafoni on Earth and Mars can help explain past and present surface erosion mechanisms on the Red Planet. The mechanisms responsible for tafoni formation on Earth include wind erosion, exfoliation, frost shattering, and, in the majority of cases, salt weathering. Microclimate variations of temperature, evaporation of salt water, disaggregation of mineral grains, as well as sandblasting, are among most common contributors that initiate the pitting of the rock surface, giving way to further development of tafoni alveoli, cavities and other erosion patterns. Dissolution of calcium carbonates and siliceous cements, or hydration of feldspars, are representative examples of tafoni erosion involving rain water, sea water or air moisture. Live organisms and biochemical processes are significant contributors to the formation and evolution of tafoni, especially in humid or water reach environments. In many instances, tafoni reflect erosion mechanism specific to environmental conditions

Mars Observer/Transfer Orbit Stage (TOS)

NASA Technical Reports Server (NTRS)

1992-01-01

In the Payload Hazardous Servicing Facility, the integrated Mars Observer/Transfer Orbit Stage (TOS) payload is ready for encapsulation in the Titan III nose fairing. The TOS booster maiden flight was dedicated to Thomas O. Paine, a former NASA administrator who strongly supported interplanetary exploration and was an early backer of the TOS program. Launched September 25, 1992 from the Kennedy Space Flight Center aboard a Titan III rocket and the TOS, the Mars Observer spacecraft was to be the first U.S. spacecraft to study Mars since the Viking missions 18 years prior. Unfortunately, the Mars Observer spacecraft fell silent just 3 days prior to entering orbit around Mars.

Higher-than-predicted saltation threshold wind speeds on Titan.

PubMed

Burr, Devon M; Bridges, Nathan T; Marshall, John R; Smith, James K; White, Bruce R; Emery, Joshua P

2015-01-01

Titan, the largest satellite of Saturn, exhibits extensive aeolian, that is, wind-formed, dunes, features previously identified exclusively on Earth, Mars and Venus. Wind tunnel data collected under ambient and planetary-analogue conditions inform our models of aeolian processes on the terrestrial planets. However, the accuracy of these widely used formulations in predicting the threshold wind speeds required to move sand by saltation, or by short bounces, has not been tested under conditions relevant for non-terrestrial planets. Here we derive saltation threshold wind speeds under the thick-atmosphere, low-gravity and low-sediment-density conditions on Titan, using a high-pressure wind tunnel refurbished to simulate the appropriate kinematic viscosity for the near-surface atmosphere of Titan. The experimentally derived saltation threshold wind speeds are higher than those predicted by models based on terrestrial-analogue experiments, indicating the limitations of these models for such extreme conditions. The models can be reconciled with the experimental results by inclusion of the extremely low ratio of particle density to fluid density on Titan. Whereas the density ratio term enables accurate modelling of aeolian entrainment in thick atmospheres, such as those inferred for some extrasolar planets, our results also indicate that for environments with high density ratios, such as in jets on icy satellites or in tenuous atmospheres or exospheres, the correction for low-density-ratio conditions is not required.

Quasi-periodic climatic changes on Mars and earth

NASA Technical Reports Server (NTRS)

Cutts, J. A.; Pollack, J. B.; Toon, O. B.; Howard, A. D.

1981-01-01

Evidence of climatic changes on Mars and the earth due to geologic and astronomical variations is discussed. Finely striped ice-free bands in the Martian polar caps have been taken to indicate that long term variations in the orbit and axial tilt of Mars have precipitated these features at the rate of a mm/yr. Photogrammetric and photometric methods have contributed to measurements of the composition and depth of the Martian caps (14-46 m), and observations of higher solar energy absorption in the northern ice cap implies greater dust deposition in that region than on the south cap; however, the transport mechanisms are not well understood. Comparisons of earth and Martian climatic variations data are made, noting a lack of information on the age intervals of marine and nonmarine sediments on the earth. The possibilities of using quantitative data other than layer thickness to constrain climate models are discussed, and the slope or albedo of layers, or the spacing of polar undulations are suggested.

AVIATR—Aerial Vehicle for In-situ and Airborne Titan Reconnaissance. A Titan airplane mission concept

NASA Astrophysics Data System (ADS)

Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; Le Mouélic, Stéphane; Rodriguez, Sebastien; Gundlach, Jay; Giannini, Francesco; Bain, Sean; Flasar, F. Michael; Hurford, Terry; Anderson, Carrie M.; Merrison, Jon; Ádámkovics, Máté; Kattenhorn, Simon A.; Mitchell, Jonathan; Burr, Devon M.; Colaprete, Anthony; Schaller, Emily; Friedson, A. James; Edgett, Kenneth S.; Coradini, Angioletta; Adriani, Alberto; Sayanagi, Kunio M.; Malaska, Michael J.; Morabito, David; Reh, Kim

2012-03-01

We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments—2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector—AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission. We propose a novel `gravity battery' climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead of using gimbaled cameras. AVIATR would climb up to 14 km altitude and descend down to 3.5 km altitude once per Earth day, allowing for repeated atmospheric structure and wind measurements all over the globe. An initial Team-X run at JPL priced the AVIATR mission at FY10 715M based on the rules stipulated in the recent Discovery announcement of opportunity. Hence we find that a standalone Titan airplane mission can achieve important science building on Cassini's discoveries and can likely do so

AVIATR - Aerial Vehicle for In-situ and Airborne Titan Reconnaissance A Titan Airplane Mission Concept

NASA Technical Reports Server (NTRS)

Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; LeMouelic, Stephane; Rodriguez, Sebastien;

Hubble Observes Surface of Titan

NASA Technical Reports Server (NTRS)

1994-01-01

Scientists for the first time have made images of the surface of Saturn's giant, haze-shrouded moon, Titan. They mapped light and dark features over the surface of the satellite during nearly a complete 16-day rotation. One prominent bright area they discovered is a surface feature 2,500 miles across, about the size of the continent of Australia.

Titan, larger than Mercury and slightly smaller than Mars, is the only body in the solar system, other than Earth, that may have oceans and rainfall on its surface, albeit oceans and rain of ethane-methane rather than water. Scientists suspect that Titan's present environment -- although colder than minus 289 degrees Fahrenheit, so cold that water ice would be as hard as granite -- might be similar to that on Earth billions of years ago, before life began pumping oxygen into the atmosphere.

Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory and his team took the images with the Hubble Space Telescope during 14 observing runs between Oct. 4 - 18. Smith announced the team's first results last week at the 26th annual meeting of the American Astronomical Society Division for Planetary Sciences in Bethesda, Md. Co-investigators on the team are Mark Lemmon, a doctoral candidate with the UA Lunar and Planetary Laboratory; John Caldwell of York University, Canada; Larry Sromovsky of the University of Wisconsin; and Michael Allison of the Goddard Institute for Space Studies, New York City.

Titan's atmosphere, about four times as dense as Earth's atmosphere, is primarily nitrogen laced with such poisonous substances as methane and ethane. This thick, orange, hydrocarbon haze was impenetrable to cameras aboard the Pioneer and Voyager spacecraft that flew by the Saturn system in the late 1970s and early 1980s. The haze is formed as methane in the atmosphere is destroyed by sunlight. The hydrocarbons produced by this methane destruction form a smog similar to that found over large cities, but is much

NIAC Phase 1 Final Study Report on Titan Aerial Daughtercraft

NASA Technical Reports Server (NTRS)

Matthies, Larry

2017-01-01

Saturns giant moon Titan has become one of the most fascinating bodies in the Solar System. Even though it is a billion miles from Earth, data from the Cassini mission reveals that Titan has a very diverse, Earth-like surface, with mountains, fluvial channels, lakes, evaporite basins, plains, dunes, and seas [Lopes 2010] (Figure 1). But unlike Earth, Titans surface likely is composed of organic chemistry products derived from complex atmospheric photochemistry [Lorenz 2008]. In addition, Titan has an active meteorological system with observed storms and precipitation-induced surface darkening suggesting a hydrocarbon cycle analogous to Earths water cycle [Turtle 2011].Titan is the richest laboratory in the solar system for studying prebiotic chemistry, which makes studying its chemistry from the surface and in the atmosphere one of the most important objectives in planetary science [Decadal 2011]. The diversity of surface features on Titan related to organic solids and liquids makes long-range mobility with surface access important [Decadal 2011]. This has not been possible to date, because mission concepts have had either no mobility (landers), no surface access (balloons and airplanes), or low maturity, high risk, and/or high development costs for this environment (e,g. large, self-sufficient, long-duration helicopters). Enabling in situ mobility could revolutionize Titan exploration, similarly to the way rovers revolutionized Mars exploration. Recent progress on several fronts has suggested that small-scale rotorcraft deployed as daughtercraft from a lander or balloon mothercraft may be an effective, affordable approach to expanding Titan surface access. This includes rapid progress on autonomous navigation capabilities of such aircraft for terrestrial applications and on miniaturization, driven by the consumer mobile electronics market, of high performance of sensors, processors, and other avionics components needed for such aircraft. Chemical analysis, for

Earthlike planets: Surfaces of Mercury, Venus, earth, moon, Mars

NASA Technical Reports Server (NTRS)

Murray, B.; Malin, M. C.; Greeley, R.

1981-01-01

The surfaces of the earth and the other terrestrial planets of the inner solar system are reviewed in light of the results of recent planetary explorations. Past and current views of the origin of the earth, moon, Mercury, Venus and Mars are discussed, and the surface features characteristic of the moon, Mercury, Mars and Venus are outlined. Mechanisms for the modification of planetary surfaces by external factors and from within the planet are examined, including surface cycles, meteoritic impact, gravity, wind, plate tectonics, volcanism and crustal deformation. The origin and evolution of the moon are discussed on the basis of the Apollo results, and current knowledge of Mercury and Mars is examined in detail. Finally, the middle periods in the history of the terrestrial planets are compared, and future prospects for the exploration of the inner planets as well as other rocky bodies in the solar system are discussed.

Life and Death on Mars and Earth

NASA Technical Reports Server (NTRS)

Zahnle, K. J.; Sleep, N. H.

1999-01-01

Failure to discover life on Mars has led a great many experts to conclude that it must be hiding. Where? The likeliest hiding places are deep beneath the surface, where geothermal heat could permit liquid water. In this the search for life on Mars parallels the search for water on Mars. Liquid water has been, at least on occasion, a geologically significant presence on the surface. Channels were cut and plains dissected. This water is now hidden, in all likelihood having drained to the base of the porous regolith, where it fills possibly frozen aquifers. Presumably any surviving biota has followed the water from the surface to its hiding places in the deep. Accordingly, we have extended our environmental impact assessment of the environmental hazards posed by large asteroid and comet impacts to Mars, and compare its case to Earth's. In particular, we address the continuous habitability of surface and subsurface environments.

Biological Contamination of Mars: Issues and Recommendations

NASA Technical Reports Server (NTRS)

1992-01-01

The ad hoc Task Group on Planetary Protection formed by the Space Studies Board (SSB) of the National Research Council focused on making recommendations concerning the protection of Mars from forward contamination (i.e., Earth to Mars) during upcoming missions by both the United States and the former Soviet Union. In so doing, it distinguished between missions whose goals include reconnaissance and measurement and those that specifically include experiments to detect life. The task group also discussed what additional knowledge will be needed in order to assure that future recommendations regarding contamination of Earth from Mars might be made with a higher degree of certainty than is now possible. Following a short introduction to the rationale underlying planetary exploration (Chapter 1) is a brief summary of approved and contemplated missions to Mars (Chapter 2). Chapter 3 briefly reviews the state of knowledge in several areas pertinent to the problem of planetary protection, in the limits of life on Earth and the abilities of known terrestrial organisms to withstand extreme environment conditions, as well as new approaches to detecting life forms. Chapter 5 includes a review and comments (made in light of current knowledge)- on the recommendations made in 'Recommendations on Quarantine Policy for Mars, Jupiter, Saturn, Uranus, Neptune, and Titan'. Updates to the recommendations made in 1978 are also given in Chapter 5. Chapter 6 gives additional recommendations concerning collection of essential data, spacecraft sterilization and bioburden assessment, and future research, as well as legal and social issues and NASA's overall planetary protection program.

Modeling dilute pyroclastic density currents on Earth and Mars

NASA Astrophysics Data System (ADS)

Clarke, A. B.; Brand, B. D.; De'Michieli Vitturi, M.

2013-12-01

The surface of Mars has been shaped extensively by volcanic activity, including explosive eruptions that may have been heavily influenced by water- or ice-magma interaction. However, the dynamics of associated pyroclastic density currents (PDCs) under Martian atmospheric conditions and controls on deposition and runout from such currents are poorly understood. This work combines numerical modeling with terrestrial field measurements to explore the dynamics of dilute PDC dynamics on Earth and Mars, especially as they relate to deposit characteristics. We employ two numerical approaches. Model (1) consists of simulation of axi-symmetric flow and sedimentation from a steady-state, depth-averaged density current. Equations for conservation of mass, momentum, and energy are solved simultaneously, and the effects of atmospheric entrainment, particle sedimentation, basal friction, temperature changes, and variations in current thickness and density are explored. The Rouse number and Brunt-Väisälä frequency are used to estimate the wavelength of internal gravity waves in a density-stratified current, which allows us to predict deposit dune wavelengths. The model predicts realistic runout distances and bedform wavelengths for several well-documented field cases on Earth. The model results also suggest that dilute PDCs on Mars would have runout distances up to three times that of equivalent currents on Earth and would produce longer-wavelength bedforms. In both cases results are heavily dependent on source conditions, grain-size characteristics, and entrainment and friction parameters. Model (2) relaxes several key simplifications, resulting in a fully 3D, multiphase, unsteady model that captures more details of propagation, including density stratification, and depositional processes. Using this more complex approach, we focus on the role of unsteady or pulsatory vent conditions typically associated with phreatomagmatic eruptions. Runout distances from Model (2) agree

Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores.

PubMed

Malkin, B Z; Lummen, T T A; van Loosdrecht, P H M; Dhalenne, G; Zakirov, A R

2010-07-14

The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R(2)Ti(2)O(7) (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions. The sets of crystal field parameters and anisotropic exchange coupling constants have been determined and their variations along the lanthanide series are discussed.

Mars and Earth: origin and abundance of volatiles.

PubMed

Anders, E; Owen, T

1977-11-04

Mars, like Earth, may have received its volatiles in the final stages of accretion, as a veneer of volatile-rich material similar to C3V carbonaceous chondrites. The high (40)Ar/(36)Ar ratio and low (36)Ar abundance on Mars, compared to data for other differentiated planets, suggest that Mars is depleted in volatiles relative to Earth-by a factor of 1.7 for K and 14 other moderately volatile elements and by a factor of 35 for (36)Ar and 15 other highly volatile elements. Using these two scaling factors, we have predicted martian abundances of 31 elements from terrestrial abundances. Comparison with the observed (36)Ar abundance suggests that outgassing on Mars has been about four times less complete than on Earth. Various predictions of the model can be checked against observation. The initial abundance of N, prior to escape, was about ten times the present value of 0.62 ppb, in good agreement with an independent estimate based on the observed enhancement in the martian (15)N/(14)N ratio (78,79). The initial water content corresponds to a 9-m layer, close to the value of >/=13 m inferred from the lack of an (18)O/(16)O fractionation (75). The predicted crustal Cl/S ratio of 0.23 agrees exactly with the value measured for martian dust (67); we estimate the thickness of this dust layer to be about 70 m. The predicted surface abundance of carbon, 290 g/cm(2), is 70 times greater than the atmospheric CO(2) value, but the CaCO(3) content inferred for martian dust (67) could account for at least one-quarter of the predicted value. The past atmospheric pressure, prior to formation of carbonates, could have been as high as 140 mbar, and possibly even 500 mbar. Finally, the predicted (129)Xe/(132)Xe ratio of 2.96 agrees fairly well with the observed value of 2.5(+2)(-1) (85). From the limited data available thus far, a curious dichotomy seems to be emerging among differentiated planets in the inner solar system. Two large planets (Earth and Venus) are fairly rich in

Titan and habitable planets around M-dwarfs.

PubMed

Lunine, Jonathan I

2010-01-01

The Cassini-Huygens mission discovered an active "hydrologic cycle" on Saturn's giant moon Titan, in which methane takes the place of water. Shrouded by a dense nitrogen-methane atmosphere, Titan's surface is blanketed in the equatorial regions by dunes composed of solid organics, sculpted by wind and fluvial erosion, and dotted at the poles with lakes and seas of liquid methane and ethane. The underlying crust is almost certainly water ice, possibly in the form of gas hydrates (clathrate hydrates) dominated by methane as the included species. The processes that work the surface of Titan resemble in their overall balance no other moon in the solar system; instead, they are most like that of the Earth. The presence of methane in place of water, however, means that in any particular planetary system, a body like Titan will always be outside the orbit of an Earth-type planet. Around M-dwarfs, planets with a Titan-like climate will sit at 1 AU--a far more stable environment than the approximately 0.1 AU where Earth-like planets sit. However, an observable Titan-like exoplanet might have to be much larger than Titan itself to be observable, increasing the ratio of heat contributed to the surface atmosphere system from internal (geologic) processes versus photons from the parent star.

Broken-Plane Maneuver Applications for Earth to Mars Trajectories

NASA Technical Reports Server (NTRS)

Abilleira, Fernando

2007-01-01

Optimization techniques are critical when investigating Earth to Mars trajectories since they have the potential of reducing the total (delta)V of a mission. A deep space maneuver (DSM) executed during the cruise may improve a trajectory by reducing the total mission V. Nonetheless, DSMs not only may improve trajectory performance (from an energetic point of view) but also open up new families of trajectories that would satisfy very specific mission requirements not achievable with ballistic trajectories. In the following pages, various specific examples showing the potential advantages of the usage of broken plane maneuvers will be introduced. These examples correspond to possible scenarios for Earth to Mars trajectories during the next decade (2010-2020).

Volcano-ice interaction as a microbial habitat on Earth and Mars.

PubMed

Cousins, Claire R; Crawford, Ian A

2011-09-01

Volcano-ice interaction has been a widespread geological process on Earth that continues to occur to the present day. The interaction between volcanic activity and ice can generate substantial quantities of liquid water, together with steep thermal and geochemical gradients typical of hydrothermal systems. Environments available for microbial colonization within glaciovolcanic systems are wide-ranging and include the basaltic lava edifice, subglacial caldera meltwater lakes, glacier caves, and subsurface hydrothermal systems. There is widespread evidence of putative volcano-ice interaction on Mars throughout its history and at a range of latitudes. Therefore, it is possible that life on Mars may have exploited these habitats, much in the same way as has been observed on Earth. The sedimentary and mineralogical deposits resulting from volcano-ice interaction have the potential to preserve evidence of any indigenous microbial populations. These include jökulhlaup (subglacial outflow) sedimentary deposits, hydrothermal mineral deposits, basaltic lava flows, and subglacial lacustrine deposits. Here, we briefly review the evidence for volcano-ice interactions on Mars and discuss the geomicrobiology of volcano-ice habitats on Earth. In addition, we explore the potential for the detection of these environments on Mars and any biosignatures these deposits may contain.

Mars extant-life campaign using an approach based on Earth-analog habitats

NASA Technical Reports Server (NTRS)

Palkovic, Lawrence A.; Wilson, Thomas J.

2005-01-01

The Mars Robotic Outpost group at JPL has identified sixteen potential momentous discoveries that if found on Mars would alter planning for the future Mars exploration program. This paper details one possible approach to the discovery of and response to the 'momentous discovery'' of extant life on Mars. The approach detailed in this paper, the Mars Extant-Life (MEL) campaign, is a comprehensive and flexible program to find living organisms on Mars by studying Earth-analog habitats of extremophile communities.

The Earth and Moon As Seen by 2001 Mars Odyssey Thermal Emission Imaging System

NASA Image and Video Library

2001-05-01

NASA Mars Odyssey spacecraft took this portrait of the Earth and its companion Moon. It was taken at a distance of 3,563,735 kilometers more than 2 million miles on April 19, 2001 as the 2001 Mars Odyssey spacecraft left the Earth.

Titan's organic chemistry

NASA Technical Reports Server (NTRS)

Sagan, C.; Thompson, W. R.; Khare, B. N.

1985-01-01

Voyager discovered nine simple organic molecules in the atmosphere of Titan. Complex organic solids, called tholins, produced by irradiation of the simulated Titanian atmosphere, are consistent with measured properties of Titan from ultraviolet to microwave frequencies and are the likely main constituents of the observed red aerosols. The tholins contain many of the organic building blocks central to life on earth. At least 100-m, and possibly kms thicknesses of complex organics have been produced on Titan during the age of the solar system, and may exist today as submarine deposits beneath an extensive ocean of simple hydrocarbons.

Planetary science: Titan's lost seas found

NASA Astrophysics Data System (ADS)

Sotin, Christophe

2007-01-01

When the Cassini spacecraft found no methane ocean swathing Saturn's moon Titan, it was a blow to proponents of an Earth-like world. The discovery of northern lakes on Titan gives them reason for cheer.

Titan's atmosphere and climate

NASA Astrophysics Data System (ADS)

Hörst, S. M.

2017-03-01

Titan is the only moon with a substantial atmosphere, the only other thick N2 atmosphere besides Earth's, the site of extraordinarily complex atmospheric chemistry that far surpasses any other solar system atmosphere, and the only other solar system body with stable liquid currently on its surface. The connection between Titan's surface and atmosphere is also unique in our solar system; atmospheric chemistry produces materials that are deposited on the surface and subsequently altered by surface-atmosphere interactions such as aeolian and fluvial processes resulting in the formation of extensive dune fields and expansive lakes and seas. Titan's atmosphere is favorable for organic haze formation, which combined with the presence of some oxygen-bearing molecules indicates that Titan's atmosphere may produce molecules of prebiotic interest. The combination of organics and liquid, in the form of water in a subsurface ocean and methane/ethane in the surface lakes and seas, means that Titan may be the ideal place in the solar system to test ideas about habitability, prebiotic chemistry, and the ubiquity and diversity of life in the universe. The Cassini-Huygens mission to the Saturn system has provided a wealth of new information allowing for study of Titan as a complex system. Here I review our current understanding of Titan's atmosphere and climate forged from the powerful combination of Earth-based observations, remote sensing and in situ spacecraft measurements, laboratory experiments, and models. I conclude with some of our remaining unanswered questions as the incredible era of exploration with Cassini-Huygens comes to an end.

You are here: Earth as seen from Mars

NASA Image and Video Library

2004-03-11

This is the first image ever taken of Earth from the surface of a planet beyond the Moon. It was taken by the Mars Exploration Rover Spirit one hour before sunrise on the 63rd martian day, or sol, of its mission. The image is a mosaic of images taken by the rover's navigation camera showing a broad view of the sky, and an image taken by the rover's panoramic camera of Earth. The contrast in the panoramic camera image was increased two times to make Earth easier to see. The inset shows a combination of four panoramic camera images zoomed in on Earth. The arrow points to Earth. Earth was too faint to be detected in images taken with the panoramic camera's color filters. http://photojournal.jpl.nasa.gov/catalog/PIA05547

Mars exploration: bridging our past and future (Invited)

NASA Astrophysics Data System (ADS)

Bibring, J.

2009-12-01

If life ever arose beyond the Earth, it is likely to have occurred on Mars: this was the belief long before any diagnostic measurements could be made. When the Viking, then Voyager missions were launched, pioneering the scientific search for extraterrestrial life, the “Plurality of Worlds” remained the dominating mindset: the possibility that the Earth is not unique and that life is generic was embraced. The lack of evidence for habitable conditions on Mars, and then Titan, dramatically changed our view. More generally, decades of space exploration have consolidated a dialectical contrast between the large commonality in the origin of the planets and the huge diversity of their present conditions. What drives planetary evolution? Mars plays a unique role in deciphering the involved processes. It has undergone many stages of planetary evolution, and has preserved a record of even the most ancient ones. The ongoing space mission, in which NASA and ESA have joined their skills and expertises, are providing a fundamentally new insight into the History of Mars and specifically into the role water has played through time. In particular, if life ever started, we now know where to search for its evidence. We’ve moved beyond just image interpretation into the realm where specific hydrated minerals such as phyllosilicates - the fingerprints of habitability - can be definitively detected, located and their context characterized. We will present recent results from Mars, and scientific clues paving the quest for ancient perennial water and potential bio-relics. We will discuss reasons why global conditions might have caused the evolutionary pathways of Mars and Earth to diverge.

Direct Measurement of Interparticle Forces of Titan Aerosol Analogs ("Tholin") Using Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Yu, Xinting; Hörst, Sarah M.; He, Chao; McGuiggan, Patricia; Bridges, Nathan T.

2017-12-01

To understand the origin of the dunes on Titan, it is important to investigate the material properties of Titan's organic sand particles on Titan. The organic sand may behave distinctively compared to the quartz/basaltic sand on terrestrial planets (Earth, Venus, and Mars) due to differences in interparticle forces. We measured the surface energy (through contact angle measurements) and elastic modulus (through Atomic Force Microscopy) of the Titan aerosol analog (tholin). We find that the surface energy of a tholin thin film is about 70.9 mN/m, and its elastic modulus is about 3.0 GPa (similar to hard polymers like PMMA and polystyrene). For two 20 μm diameter particles, the theoretical cohesion force is therefore 3.3 μN. We directly measured interparticle forces for relevant materials: tholin particles are 0.8 ± 0.6 μN, while the interparticle cohesion between walnut shell particles (a typical model materials for the Titan Wind Tunnel, TWT) is only 0.4 ± 0.1 μN. The interparticle cohesion forces are much larger for tholins and presumably Titan sand particles than materials used in the TWT. This suggests that we should increase the interparticle force in both analog experiments (TWT) and threshold models to correctly translate the results to real Titan conditions. The strong cohesion of tholins may also inform us how the small aerosol particles (˜1 μm) in Titan's atmosphere are transformed into large sand particles (˜200 μm). It may also support the cohesive sand formation mechanism suggested by Rubin and Hesp (2009), where only unidirectional wind is needed to form linear dunes on Titan.

Gravity effects on sediment sorting: limitations of models developed on Earth for Mars

NASA Astrophysics Data System (ADS)

Kuhn, Nikolaus J.; Kuhn, Brigitte; Gartmann, Andres

2015-04-01

Most studies on surface processes on planetary bodies assume that the use of empirical models developed for Earth is possible if the mathematical equations include all the relevant factors, such as gravity, viscosity and the density of water and sediment. However, most models for sediment transport on Earth are at least semi-empirical, using coefficients to link observed sediment movement to controlling factors such as flow velocity, slope and channel dimensions. However, using roughness and drag coefficients, as well as parameters describing incipient motion of particles, observed on Earth on another planet, violates, strictly speaking, the boundary conditions set for their application by fluid dynamics because the coefficienst describe a flow condition, not a particle property. Reduced gravity affects the flow around a settling partcile or over the bed of a watercourse, therefore data and models from Earth do not apply to another planet. Comparing observations from reduced gravity experiments and model results obtained on Earth confirm the significance of this error, e.g. by underestimating settling velocities of sandy particles by 10 to 50% for Mars when using models from Earth. In this study, the relevance of this error is examined by simulating the sorting of sediment deposited from water flowing on Mars. The results indicate that sorting on Mars is less pronounced than models calibrated on Earth suggest. This has implications for the selection of landing sites and, more importantly, the identification of strata potentially bearing traces of past life during rover missions on Mars.

Spacecraft navigation at Mars using earth-based and in situ radio tracking techniques

NASA Astrophysics Data System (ADS)

Thurman, S. W.; Edwards, C. D.; Kahn, R. D.; Vijayaraghavan, A.; Hastrup, R. C.; Cesarone, R. J.

1992-08-01

A survey of earth-based and in situ radiometric data types and results from a number of studies investigating potential radio navigation performance for spacecraft approaching/orbiting Mars and for landed spacecraft and rovers on the surface of Mars are presented. The performance of Doppler, ranging and interferometry earth-based data types involving single or multiple spacecraft is addressed. This evaluation is conducted with that of in situ data types, such as Doppler and ranging measurements between two spacecraft near Mars, or between a spacecraft and one or more surface radio beacons.

Spacecraft navigation at Mars using earth-based and in situ radio tracking techniques

NASA Technical Reports Server (NTRS)

Thurman, S. W.; Edwards, C. D.; Kahn, R. D.; Vijayaraghavan, A.; Hastrup, R. C.; Cesarone, R. J.

1992-01-01

A survey of earth-based and in situ radiometric data types and results from a number of studies investigating potential radio navigation performance for spacecraft approaching/orbiting Mars and for landed spacecraft and rovers on the surface of Mars are presented. The performance of Doppler, ranging and interferometry earth-based data types involving single or multiple spacecraft is addressed. This evaluation is conducted with that of in situ data types, such as Doppler and ranging measurements between two spacecraft near Mars, or between a spacecraft and one or more surface radio beacons.

Earth-like sand fluxes on Mars.

PubMed

Bridges, N T; Ayoub, F; Avouac, J-P; Leprince, S; Lucas, A; Mattson, S

2012-05-09

Strong and sustained winds on Mars have been considered rare, on the basis of surface meteorology measurements and global circulation models, raising the question of whether the abundant dunes and evidence for wind erosion seen on the planet are a current process. Recent studies showed sand activity, but could not determine whether entire dunes were moving--implying large sand fluxes--or whether more localized and surficial changes had occurred. Here we present measurements of the migration rate of sand ripples and dune lee fronts at the Nili Patera dune field. We show that the dunes are near steady state, with their entire volumes composed of mobile sand. The dunes have unexpectedly high sand fluxes, similar, for example, to those in Victoria Valley, Antarctica, implying that rates of landscape modification on Mars and Earth are similar.

The carbon cycle on early Earth--and on Mars?

PubMed

Grady, Monica M; Wright, Ian

2006-10-29

One of the goals of the present Martian exploration is to search for evidence of extinct (or even extant) life. This could be redefined as a search for carbon. The carbon cycle (or, more properly, cycles) on Earth is a complex interaction among three reservoirs: the atmosphere; the hydrosphere; and the lithosphere. Superimposed on this is the biosphere, and its presence influences the fixing and release of carbon in these reservoirs over different time-scales. The overall carbon balance is kept at equilibrium on the surface by a combination of tectonic processes (which bury carbon), volcanism (which releases it) and biology (which mediates it). In contrast to Earth, Mars presently has no active tectonic system; neither does it possess a significant biosphere. However, these observations might not necessarily have held in the past. By looking at how Earth's carbon cycles have changed with time, as both the Earth's tectonic structure and a more sophisticated biology have evolved, and also by constructing a carbon cycle for Mars based on the carbon chemistry of Martian meteorites, we investigate whether or not there is evidence for a Martian biosphere.

Plateau on temperature dependence of magnetization of nanostructured rare earth titanates

NASA Astrophysics Data System (ADS)

Rinkevich, A. B.; Korolev, A. V.; Samoylovich, M. I.; Demokritov, S. O.; Perov, D. V.

2018-05-01

Magnetic properties of nanocomposite materials containing particles of rare earth titanates of R2Ti2O7 type, where R is a rare earth ion, including "spin ice" materials are investigated. The descending branches of hysteresis loop have been studied in detail in temperature range from 2 to 50 K. It has been shown that nanocomposites with Yb2Ti2O7, Dy2Ti2O7 and Er2Ti2O7 particles have one intersection point of the descending branches in some temperature range unlike many other nanocomposites. It is shown that magnetization has only weak temperature dependence near this point. It has been obtained that nanocomposites with Pr2Ti2O7 and Nd2Ti2O7 particles have no hysteresis loop. All above findings point out to unusual magnetic structures of the studied samples.

Feasibility study of a single, elliptical heliocentric Earth-Mars trajectory

NASA Technical Reports Server (NTRS)

Blake, M.; Fulgham, K.; Westrup, S.

1989-01-01

The initial intent of this design project was to evaluate the existence and feasibility of a single elliptical heliocentric Earth/Mars trajectory. This trajectory was constrained to encounter Mars twice in its orbit, within a time interval of 15 to 180 Earth days between encounters. The single ellipse restriction was soon found to be prohibitive for reasons shown later. Therefore, the approach taken in the design of the round-trip mission to Mars was to construct single-leg trajectories which connected two planets on two prescribed dates. Three methods of trajectory design were developed. Method 1 is an eclectic approach and employs Gaussian Orbit Determination (Method 1A) and Lambert-Euler Preliminary Orbit Determination (Method 1B) in conjunction with each other. Method 2 is an additional version of Lambert's Solution to orbit determination, and both a coplanar and a noncoplanar solution were developed within Method 2. In each of these methods, the fundamental variables are two position vectors and the time between the position vectors. In all methods, the motion was considered Keplerian motion and the reference frame origin was located at the sun. Perturbative effects were not considered in Method 1. The feasibility study of round-trip Earth/Mars trajectories maintains generality by considering only heliocentric trajectory parameters and planetary approach conditions. The coordinates and velocity components of the planets, for the standard epoch J2000, were computed from an approximate set of osculating elements by the procedure outlined in an ephemeris of coordinates.

Interplanetary Mission Design Handbook: Earth-to-Mars Mission Opportunities 2026 to 2045

NASA Technical Reports Server (NTRS)

Burke, Laura M.; Falck, Robert D.; McGuire, Melissa L.

2010-01-01

The purpose of this Mission Design Handbook is to provide trajectory designers and mission planners with graphical information about Earth to Mars ballistic trajectory opportunities for the years of 2026 through 2045. The plots, displayed on a departure date/arrival date mission space, show departure energy, right ascension and declination of the launch asymptote, and target planet hyperbolic arrival excess speed, V(sub infinity), for each launch opportunity. Provided in this study are two sets of contour plots for each launch opportunity. The first set of plots shows Earth to Mars ballistic trajectories without the addition of any deep space maneuvers. The second set of plots shows Earth to Mars transfer trajectories with the addition of deep space maneuvers, which further optimize the determined trajectories. The accompanying texts explains the trajectory characteristics, transfers using deep space maneuvers, mission assumptions and a summary of the minimum departure energy for each opportunity.

Gravity effects on sediment sorting: limitations of models developed on Earth for Mars

NASA Astrophysics Data System (ADS)

Kuhn, N. J.; Kuhn, B.; Gartmann, A.

2015-10-01

Most studies on surface processes on planetary bodies assume that the use of empirical models developed for Earth is possible if the mathematical equations include all the relevant factors, such as gravity, viscosity and the density of water and sediment. However, most models for sediment transport on Earth are at least semi-empirical, using coefficients to link observed sediment movement to controlling factors such as flow velocity, slope and channel dimensions. However, using roughness and drag coefficients, as well as parameters describing incipient motion of particles, observed on Earth on another planet, violates, strictly speaking, the boundary conditions set for their application by fluid dynamics because the coefficienst describe a flow condition, not a particle property. Reduced gravity affects the flow around a settling partcile or over the bed of a watercourse, therefore data and models from Earth do not apply to another planet. Comparing observations from reduced gravity experiments and model results obtained on Earth confirm the significance of this error, e.g. by underestimating settling velocities of sandy particles by 10 to 50% for Mars when using models from Earth. In this study, the relevance of this error is examined by simulating the sorting of sediment deposited from water flowing on Mars. The results indicate that sorting on Mars is less pronounced than models calibrated on Earth suggest. This has implications for the selection of landing sites and,more importantly, the identification of strata potentially bearing traces of past life during rover missions on Mars. try, 2001

Comparisons of the North Polar Cap of Mars and the Earth's Northern Hemisphere snow cover

NASA Technical Reports Server (NTRS)

Foster, J.; Owe, M.; Capen, C.

1985-01-01

The boundaries of the polar caps of Mars have been measured on more than 3000 photographs since 1905 from the plate collection at the Lowell Observatory. For the Earth the polar caps have been accurately mapped only since the mid 1960's when satellites were first available to synoptically view the polar regions. The polar caps of both planets wax and wane in response to changes in the seasons, and interannual differences in polar cap behavior on Mars as well as Earth are intimately linked to global energy balance. In this study data on the year to year variations in the extent of the polar caps of Mars and Earth were assembled and analyzed together with data on annual variations in solar activity to determine if associations exist between these data. It was found that virtually no correlation exists between measurements of Mars north polar cap and solar variability. An inverse relationship was found between variations in the size of the north polar caps of Mars and Earth, although only 6 years of concurrent data were available for comparison.

Lunar and Planetary Science XXXV: Ancient Mars Water and Landforms

NASA Technical Reports Server (NTRS)

2004-01-01

Titles in this section include: 1) Giant Lowland Polygons: Relics of an Ancient Martian Ocean? 2) Lake Shorelines: Earth Analogs for Hypothesized Martian Coastal Features; 3) Complex Evolution of Paleolacustrine Systems on Mars: An Example from the Holden Crater; 4) Geomorphology and Hydraulics of Ma'adim Vallis, Mars, During a Noachian/Hesperian Boundary Paleoflood; 5) Geologic Evolution of Dao Vallis, Mars; 6) Advances in Reconstructing the Geologic History of the Chryse Region Outflow Channels on Mars; 7) Ravi Vallis, Mars - Paleoflood Origin and Genesis of Secondary Chaos Zones; 8) Walla Walla Vallis and Wallula Crater: Two Recently Discovered Martian Features Record Aqueous History; 9) Tharsis Recharge: a Source of Groundwater for Martian Outflow Channels; 10) Factors Controlling Water Volumes and Release Rates in Martian Outflow Channels; 11) Significance of Confined Cavernous Systems for Outflow Channel Water Sources, Reactivation Mechanisms and Chaos Formation; 12) Systematic Differences in Topography of Martian and Terrestrial Drainage Basins; 13) Waves on Seas of Mars and Titan: Wind-Tunnel Experiments on Wind-Wave Generation in Extraterrestrial Atmospheres.

On the paleo-magnetospheres of Earth and Mars

NASA Astrophysics Data System (ADS)

Scherf, Manuel; Khodachenko, Maxim; Alexeev, Igor; Belenkaya, Elena; Blokhina, Marina; Johnstone, Colin; Tarduno, John; Lammer, Helmut; Tu, Lin; Guedel, Manuel

2017-04-01

The intrinsic magnetic field of a terrestrial planet is considered to be an important factor for the evolution of terrestrial atmospheres. This is in particular relevant for early stages of the solar system, in which the solar wind as well as the EUV flux from the young Sun were significantly stronger than at present-day. We therefore will present simulations of the paleo-magnetospheres of ancient Earth and Mars, which were performed for ˜4.1 billion years ago, i.e. the Earth's late Hadean eon and Mars' early Noachian. These simulations were performed with specifically adapted versions of the Paraboloid Magnetospheric Model (PMM) of the Skobeltsyn Institute of Nuclear Physics of the Moscow State University, which serves as ISO-standard for the Earth's magnetic field (see e.g. Alexeev et al., 2003). One of the input parameters into our model is the ancient solar wind pressure. This is derived from a newly developed solar/stellar wind evolution model, which is strongly dependent on the initial rotation rate of the early Sun (Johnstone et al., 2015). Another input parameter is the ancient magnetic dipole field. In case of Earth this is derived from measurements of the paleomagnetic field strength by Tarduno et al., 2015. These data from zircons are varying between 0.12 and 1.0 of today's magnetic field strength. For Mars the ancient magnetic field is derived from the remanent magnetization in the Martian crust as measured by the Mars Global Surveyor MAG/ER experiment. These data together with dynamo theory are indicating an ancient Martian dipole field strength in the range of 0.1 to 1.0 of the present-day terrestrial dipole field. For the Earth our simulations show that the paleo-magnetosphere during the late Hadean eon was significantly smaller than today, with a standoff-distance rs ranging from ˜3.4 to 8 Re, depending on the input parameters. These results also have implications for the early terrestrial atmosphere. Due to the significantly higher EUV flux, the

Mars Sample Return mission: Two alternate scenarios

NASA Technical Reports Server (NTRS)

1991-01-01

Two scenarios for accomplishing a Mars Sample Return mission are presented herein. Mission A is a low cost, low mass scenario, while Mission B is a high technology, high science alternative. Mission A begins with the launch of one Titan IV rocket with a Centaur G' upper stage. The Centaur performs the trans-Mars injection burn and is then released. The payload consists of two lander packages and the Orbital Transfer Vehicle, which is responsible for supporting the landers during launch and interplanetary cruise. After descending to the surface, the landers deploy small, local rovers to collect samples. Mission B starts with 4 Titan IV launches, used to place the parts of the Planetary Transfer Vehicle (PTV) into orbit. The fourth launch payload is able to move to assemble the entire vehicle by simple docking routines. Once complete, the PTV begins a low thrust trajectory out from low Earth orbit, through interplanetary space, and into low Martian orbit. It deploys a communication satellite into a 1/2 sol orbit and then releases the lander package at 500 km altitude. The lander package contains the lander, the Mars Ascent Vehicle (MAV), two lighter than air rovers (called Aereons), and one conventional land rover. The entire package is contained with a biconic aeroshell. After release from the PTV, the lander package descends to the surface, where all three rovers are released to collect samples and map the terrain.

Science in Exploration: From the Moon to Mars and Back Home to Earth

NASA Technical Reports Server (NTRS)

Garvin, James B.

2007-01-01

NASA is embarking on a grand journey of exploration that naturally integrates the past successes of the Apollo missions to the Moon, as well as robotic science missions to Mars, to Planet Earth, and to the broader Universe. The US Vision for Space Exporation (VSE) boldly lays out a plan for human and robotic reconnaissance of the accessible Universe, starting with the surface of the Moon, and later embracing the surface of Mars. Sustained human and robotic access to the Moon and Mars will enable a new era of scientific investigation of our planetary neighbors, tied to driving scientific questions that pertain to the evolution and destiny of our home planet, but which also can be related to the search habitable worlds across the nearby Universe. The Apollo missions provide a vital legacy for what can be learned from the Moon, and NASA is now poised to recapture the lunar frontier starting with the flight of the Lunar Reconnaissance Orbiter (LRO) in late 2008. LRO will provide a new scientific context from which joint human and robotic exploration will ensue, guided by objectives some of which are focused on the grandest scientific challenges imaginable : Where did we come from? Are we alone? and Where are we going? The Moon will serve as an essential stepping stone for sustained human access and exploration of deep space and as a training ground while robotic missions with ever increasing complexity probe the wonders of Mars. As we speak, an armada of spacecraft are actively investigating the red planet both from orbit (NASA's Mars Reconnaissance Orbiter and Mars Odyssey Orbiter, plus ESA's Mars Express) and from the surface (NASA's twin Mars Exploration Rovers, and in 2008 NASA's Phoenix polar lander). The dramatically changing views of Mars as a potentially habitable world, with its own flavor of global climate change and unique climate records, provides a new vantage point from which to observe and question the workings of our own planet Earth. By 2010 NASA will

Magnetobraking: Use of tether electrodynamic drag for Earth return from Mars

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.

1994-01-01

It has often been proposed that a vehicle returning from Mars will use aerobraking in the Earth's atmosphere to dissipate hyperbolic excess velocity to capture into Earth orbit. Here a different system for dissipating excess velocity without expenditure of reaction mass, magnetobraking, is proposed. Magnetobraking uses the force on an electrodynamic tether in the Earth's magnetic field to produce thrust. An electrodynamic tether is deployed from the spacecraft as it approaches the Earth. The Earth's magnetic field produces a force on electrical current in the tether. If the tether is oriented perpendicularly to the Earth's magnetic field and to the direction of motion of the spacecraft, force produced by the Earth's magnetic field can be used to either brake or accelerate the spacecraft without expenditure of reaction mass. The peak acceleration on the Mars return is 0.007 m/sq sec, and the amount of braking possible is dependent on the density and current-carrying capacity of the tether, but is independent of length. A superconducting tether is required. The required critical current is shown to be within the range of superconducting technology now available in the laboratory.

Physical conditions on the early Earth.

PubMed

Lunine, Jonathan I

2006-10-29

The formation of the Earth as a planet was a large stochastic process in which the rapid assembly of asteroidal-to-Mars-sized bodies was followed by a more extended period of growth through collisions of these objects, facilitated by the gravitational perturbations associated with Jupiter. The Earth's inventory of water and organic molecules may have come from diverse sources, not more than 10% roughly from comets, the rest from asteroidal precursors to chondritic bodies and possibly objects near Earth's orbit for which no representative class of meteorites exists today in laboratory collections. The final assembly of the Earth included a catastrophic impact with a Mars-sized body, ejecting mantle and crustal material to form the Moon, and also devolatilizing part of the Earth. A magma ocean and steam atmosphere (possibly with silica vapour) existed briefly in this period, but terrestrial surface waters were below the critical point within 100 million years after Earth's formation, and liquid water existed continuously on the surface within a few hundred million years. Organic material delivered by comets and asteroids would have survived, in part, this violent early period, but frequent impacts of remaining debris probably prevented the continuous habitability of the Earth for one to several hundred million years. Planetary analogues to or records of this early time when life began include Io (heat flow), Titan (organic chemistry) and Venus (remnant early granites).

Two planets: Earth and Mars - One salt model: The Hydrothermal SCRIW-Model

NASA Astrophysics Data System (ADS)

Hovland, M. T.; Rueslaatten, H.; Johnsen, H. K.; Indreiten, T.

2011-12-01

One of the common characteristics of planets Earth and Mars is that both host water (H2O) and large accumulations of salt. Whereas Earth's surface-environment can be regarded as 'water-friendly' and 'salt hostile', the reverse can be said for the surface of Mars. This is because liquid water is stable on Earth, and the atmosphere transports humidity around the globe, whereas on planet Mars, liquid water is unstable, rendering the atmosphere dry and, therefore, 'salt-friendly'. The riddle as to how the salt accumulated in various locations on those two planets is one of long-lasting and great debate. The salt accumulations on Earth are traditionally termed 'evaporites', meaning that they formed by the evaporation of large masses of seawater. How the accumulations on Mars formed is much harder to explain, with a similar model, as surface water, representing a large ocean only existed briefly. Although water molecules and OH-groups may exist in abundance in bound form (crystal water, adsorbed water, etc.), the only place where free water is expected to be stable on Mars is within underground faults, fractures, and crevices. Here it likely occurs as brine or in the form of ice. Based on these conditions, a key to understanding the accumulation of large deposits of salt on both planets is linked to how brines behave in the subsurface when pressurized and heated beyond their supercritical point. At depths greater than about 3 km (i.e., a pressure, P>300 bars) water will no longer boil in a steam phase. Rather, it becomes supercritical and will form a supercritical water 'vapor' (SCRIW) with a specific gravity of typically 0.3 g/cm3. An important characteristic of SCRIW is its inability to dissolve the common sea salts. The salt dissolved in the brines will therefore precipitate as solid particles when brines (seawater on the Earth) move into the supercritical P&T-domain (above 400 C and 300 bars). Numerical modeling of a hydrothermal system in the Atlantis II Deep of the

Simultaneous Modeling of Gradual SEP Events at the Earth and the Mars

NASA Astrophysics Data System (ADS)

Hu, J.; Li, G.

2017-12-01

Solar Energetic Particles (SEP) event is the number one space hazard for spacecraft instruments and astronauts' safety. Recent studies have shown that both longitudinal and radial extent of SEP events can be very significant. In this work, we use the improved Particle Acceleration and Transport in the Heliosphere (iPATH) model to simulate gradual SEP events that have impacts upon both the Earth and the Mars. We follow the propagation of a 2D CME-driven shock. Particles are accelerated at the shock via the diffusive shock acceleration (DSA) mechanism. Transport of the escaped particles to the Earth and the Mars is then followed using a backward stochastic differential equation method. Perpendicular diffusion is considered in both the DSA and the transport process. Model results such as time intensity profile and energetic particle spectrum at the two locations are compared to understand the spatial extent of an SEP event. Observational data at the Earth and the Mars are also studied to validate the model.

Simulation of Earth-Moon-Mars Environments for the Assessment of Organ Doses

NASA Astrophysics Data System (ADS)

Kim, M. Y.; Schwadron, N. A.; Townsend, L.; Cucinotta, F. A.

2010-12-01

Space radiation environments for historically large solar particle events (SPE) and galactic cosmic rays (GCR) at solar minimum and solar maximum are simulated in order to characterize exposures to radio-sensitive organs for missions to low-Earth orbit (LEO), moon, and Mars. Primary and secondary particles for SPE and GCR are transported through the respective atmosphere of Earth or Mars, space vehicle, and astronaut’s body tissues using the HZETRN/QMSFRG computer code. In LEO, exposures are reduced compared to deep space because particles are deflected by the Earth’s magnetic field and absorbed by the solid body of the Earth. Geomagnetic transmission function as a function of altitude was applied for the particle flux of charged particles, and the shift of the organ exposures to higher velocity or lower stopping powers compared to those in deep space was analyzed. In the transport through Mars atmosphere, a vertical distribution of atmospheric thickness was calculated from the temperature and pressure data of Mars Global Surveyor, and the directional cosine distribution was implemented to describe the spherically distributed atmospheric distance along the slant path at each altitude. The resultant directional shielding by Mars atmosphere at solar minimum and solar maximum was used for the particle flux simulation at various altitudes on the Martian surface. Finally, atmospheric shielding was coupled with vehicle and body shielding for organ dose estimates. We made predictions of radiation dose equivalents and evaluated acute symptoms at LEO, moon, and Mars at solar minimum and solar maximum.

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.

Titan as the Abode of Life

NASA Technical Reports Server (NTRS)

Mckay, Christopher P.

2016-01-01

Titan is the only world we know other than Earth that has a liquid on its surface. It has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in the atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic - polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the Universe is full of diverse and wondrous life forms.

Titan as the Abode of Life

NASA Astrophysics Data System (ADS)

McKay, Christopher P.

2016-02-01

Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic - polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms.

Titan as the Abode of Life.

PubMed

McKay, Christopher P

2016-02-03

Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H₂O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic-polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms.

Fluvial geomorphology on Earth-like planetary surfaces: A review.

PubMed

Baker, Victor R; Hamilton, Christopher W; Burr, Devon M; Gulick, Virginia C; Komatsu, Goro; Luo, Wei; Rice, James W; Rodriguez, J A P

2015-09-15

Morphological evidence for ancient channelized flows (fluvial and fluvial-like landforms) exists on the surfaces of all of the inner planets and on some of the satellites of the Solar System. In some cases, the relevant fluid flows are related to a planetary evolution that involves the global cycling of a volatile component (water for Earth and Mars; methane for Saturn's moon Titan). In other cases, as on Mercury, Venus, Earth's moon, and Jupiter's moon Io, the flows were of highly fluid lava. The discovery, in 1972, of what are now known to be fluvial channels and valleys on Mars sparked a major controversy over the role of water in shaping the surface of that planet. The recognition of the fluvial character of these features has opened unresolved fundamental questions about the geological history of water on Mars, including the presence of an ancient ocean and the operation of a hydrological cycle during the earliest phases of planetary history. Other fundamental questions posed by fluvial and fluvial-like features on planetary bodies include the possible erosive action of large-scale outpourings of very fluid lavas, such as those that may have produced the remarkable canali forms on Venus; the ability of exotic fluids, such as methane, to create fluvial-like landforms, as observed on Saturn's moon, Titan; and the nature of sedimentation and erosion under different conditions of planetary surface gravity. Planetary fluvial geomorphology also illustrates fundamental epistemological and methodological issues, including the role of analogy in geomorphological/geological inquiry.

Morphologic and Dynamic Similarities Between Polygonal Dunes on Mars and Interference Ripples on Earth

NASA Astrophysics Data System (ADS)

Rubin, D. M.; Newman, C. E.

2012-12-01

Some dunes in craters on Mars are similar in morphology to ripples formed in complicated multidirectional flows on Earth. Similarities in morphology of these ripples on Earth and dunes on Mars include (1) relatively symmetrical cross-sections, and (2) crests with planform polygonal patterns, "tile" patterns, or "ladderback" structure. On Earth, bedforms with these morphologies are produced by complicated directionally-varying flows such as those generated by interfering waves (Figure 1), recirculating flows in the lee of large dunes, and recirculating flows in lateral separation eddies in rivers. Here we hypothesize that dunes with these morphologies on Mars (Figure 2) are also formed by multidirectional flows. Processes that might produce multidirectional winds on Mars include: heating and cooling that cause daily changes in wind direction; winds that vary in direction seasonally or with the passage of storms; and recirculating flows within steep-walled craters or within the troughs of larger dunes. This work was funded by NASA Mars Data Analysis Program.igure 1. Polygonal ripples formed by waves in shallow water; boot print is 30 cm long. igure 2. Polygonal dunes in Victoria Crater, Mars; crater is approximately 700 m in diameter and 70 m deep; image from NASA/JPL-Caltech/University of Arizona.

Solar forcing, and ionospheric ion outflow from Venus, Earth and Mars - A comparison

NASA Astrophysics Data System (ADS)

Lundin, R. N.

2012-12-01

Solar forcing by e.g. EUV radiation and the solar wind leads to outflow and escape of ionospheric ions from Earth, Venus and Mars. In-situ measurements in the Earth's space environment have demonstrated that the ion escape rate correlates with the magnitude of solar forcing, i.e. high solar EUV and solar wind forcing leads to enhanced escape rates. The Terrestrial outflow is dominated by H+ and O+ suggesting that the ultimate origin of outflowing ions is water. Recent measurements from the two arid planets Mars and Venus, their atmospheres dominated by CO2, display characteristics similar to that of the Earth - an outflow dominated by hydrogen (H+) and oxygen (O+, O2+) ions. Despite major differences in atmospheric composition, the composition of the ion outflow from Earth and Venus is very similar, i.e. H+ and O+ dominates and the outflow has a stoichiometric H/O ratio of close to 2. The latter implies escape of water. The ion outflow from Mars is dominated by O+, O2+, and H+. Here the stoichiometric ratio between hydrogen and oxygen ion is ≈1, implying that if the ion outflow originates from water, about half of the hydrogen mass disappears by other means. The primary origin of the ion outflow from Earth, Venus and Mars is a complex issue. Nevertheless, a predominant hydrogen and oxygen loss implies that water can easily escape planets orbiting close to the Sun, while Carbon-based molecules (e.g. CO2) resides more easily. Observations shows that the outflow of e.g. CO+ and CO2+ from Mars and Venus is minute compared to the outflow of hydrogen and oxygen ions. Magnetic shielding is an issue affecting the net ion outflow and escape from a planet, because acceleration processes are also the characteristics of magnetized plasmas. Recent findings suggests that, despite magnetic field pile-up at Mars and Venus, the stand-off distance is insufficient to prohibit a direct interaction between the solar wind and the magnetized ionospheric plasma in the induced

Ocean Fertilization from Giant Icebergs on Earth and Early Mars

NASA Astrophysics Data System (ADS)

Uceda, E. R.; Fairen, A. G.; Rodriguez, J. A. P.; Woodworth-Lynas, C.

2016-05-01

Assuming that life existed on Mars coeval to glacial activity, enhanced concentrations of organic carbon could be anticipated near iceberg trails, analogous to what is observed in polar oceans on Earth.

Advances in Architectural Elements For Future Missions to Titan

NASA Astrophysics Data System (ADS)

Reh, Kim; Coustenis, Athena; Lunine, Jonathan; Matson, Dennis; Lebreton, Jean-Pierre; Vargas, Andre; Beauchamp, Pat; Spilker, Tom; Strange, Nathan; Elliott, John

2010-05-01

The future exploration of Titan is of high priority for the solar system exploration community as recommended by the 2003 National Research Council (NRC) Decadal Survey [1] and ESA's Cosmic Vision Program themes. Recent Cassini-Huygens discoveries continue to emphasize that Titan is a complex world with very many Earth-like features. Titan has a dense, nitrogen atmosphere, an active climate and meteorological cycles where conditions are such that the working fluid, methane, plays the role that water does on Earth. Titan's surface, with lakes and seas, broad river valleys, sand dunes and mountains was formed by processes like those that have shaped the Earth. Supporting this panoply of Earth-like processes is an ice crust that floats atop what might be a liquid water ocean. Furthermore, Titan is rich in very many different organic compounds—more so than any place in the solar system, except Earth. The Titan Saturn System Mission (TSSM) concept that followed the 2007 TandEM ESA CV proposal [2] and the 2007 Titan Explorer NASA Flagship study [3], was examined [4,5] and prioritized by NASA and ESA in February 2009 as a mission to follow the Europa Jupiter System Mission. The TSSM study, like others before it, again concluded that an orbiter, a montgolfiere hot-air balloon and a surface package (e.g. lake lander, Geosaucer (instrumented heat shield), …) are very high priority elements for any future mission to Titan. Such missions could be conceived as Flagship/Cosmic Vision L-Class or as individual smaller missions that could possibly fit into NASA New Frontiers or ESA Cosmic Vision M-Class budgets. As a result of a multitude of Titan mission studies, a clear blueprint has been laid out for the work needed to reduce the risks inherent in such missions and the areas where advances would be beneficial for elements critical to future Titan missions have been identified. The purpose of this paper is to provide a brief overview of the flagship mission architecture and

Reorientation Timescales and Pattern Dynamics for Titan's Dunes: Does the Tail Wag the Dog or the Dragon?

NASA Astrophysics Data System (ADS)

Ewing, R. C.; Hayes, A. G.; McCormick, C.; Ballard, C.; Troy, S. A.

2012-04-01

longest reorientation time scales (~105 migration timescales), while the topographically or spatially isolated patches of dunes show the shortest reorientation times (~103 migration timescales). In addition, comparisons between spacing and defect density reveal that the well-organized patterns plot along an expected trend with Earth and Mars' largest, well-organized fields. Patterns on Earth and Mars that have been degraded and broken by environmental change fall off this trend and similarly, so do the isolated dune patterns on Titan fall suggesting changing environmental conditions such as wind regime and/or sediment availability have influenced the dunes on Titan. Crestline orientations in these areas suggest star and crescentic (barchans) morphologies in addition to linear dunes. Our results suggest that Titan's dunes may react to gross bedform transport averaged over orbital timescales, relaxing the requirement that a single modern wind regime is necessary to produce the observed well-organized dune patterns. We find signals of environmental change within the smallest patterns suggesting that the dunes may be recently reoriented or are reorienting to one component of a longer timescale wind regime with a duty cycle that persists over many seasonal cycles.

Titan as the Abode of Life

PubMed Central

McKay, Christopher P.

2016-01-01

Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan’s atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic—polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms. PMID:26848689

Partitioning of Oxygen During Core Formation on Earth and Mars

NASA Astrophysics Data System (ADS)

Rubie, D. C.; Gessmann, C. K.; Frost, D. J.

2003-12-01

Core formation on Earth and Mars involved the physical separation of Fe-Ni metal alloy from silicate, most likely in deep magma oceans. Although core-formation models explain many aspects of mantle geochemistry, they do not account for large differences between the compositions of the mantles of Earth ( ˜8 wt% FeO) and Mars ( ˜18 wt% FeO) or the much smaller mass fraction of the Martian core. Here we explain these differences using new experimental results on the solubility of oxygen in liquid Fe-Ni alloy, which we have determined at 5-23 GPa, 2100-2700 K and variable oxygen fugacities using a multianvil apparatus. Oxygen solubility increases with increasing temperature and oxygen fugacity and decreases with increasing pressure. Thus, along a high temperature adiabat (e.g. after formation of a deep magma ocean on Earth), oxygen solubility is high at depths up to about 2000 km but decreases strongly at greater depths where the effect of high pressure dominates. For modeling oxygen partitioning during core formation, we assume that Earth and Mars both accreted from oxidized chondritic material with a silicate fraction initially containing around 18 wt% FeO. In a terrestrial magma ocean, 1200-2000 km deep, high temperatures resulted in the extraction of FeO from the silicate magma ocean, due to the high solubility of oxygen in the segregating metal, leaving the mantle with its present FeO content of ˜8 wt%. Lower temperatures of a Martian magma ocean resulted in little or no extraction of FeO from the mantle, which thus remained unchanged at about 18 wt%. The mass fractions of segregated metal are consistent with the mass fraction of the Martian core being small relative to that of the Earth. FeO extracted from the Earth's magma ocean by segregating core-forming liquid may have contributed to chemical heterogeneities in the lowermost mantle, a FeO-rich D'' layer and the light element budget of the core.

Benefits of in situ propellant utilization for a Mars sample return mission

NASA Technical Reports Server (NTRS)

Wadel, Mary F.

1993-01-01

Previous Mars rover sample return mission studies have shown a requirement for Titan 4 or STS Space Shuttle launch vehicles to complete a sample return from a single Mars site. These studies have either used terrestrial propellants or considered in situ production of methane and oxygen for the return portion of the mission. Using in situ propellants for the return vehicles reduces the Earth launch mass and allows for a smaller Earth launch vehicle, since the return propellant is not carried from Earth. Carbon monoxide and oxygen (CO/O2) and methane and oxygen (CH4/O2) were investigated as in situ propellants for a Mars sample return mission and the results were compared to a baseline study performed by the Jet Propulsion Laboratory using terrestrial propellants. Capability for increased sample return mass, use of an alternate launch vehicle, and an additional mini-rover as payload were included. CO/O2 and CH4/O2 were found to decrease the baseline Earth launch mass by 13.6 and 9.2 percent, respectively. This resulted in higher payload mass margins for the baseline Atlas 2AS launch vehicle. CO/O2 had the highest mass margin. And because of this, it was not only possible to increase the sample return mass and carry an additional mini-rover, but was also possible to use the smaller Atlas 2A launch vehicle.

Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

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

Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney

The arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and a thick atmosphere with a pressure of 1.4 atm at surface level - in 2004 opened up a new chapter in the history of Solar System exploration. The mission revealed Titan as a world with striking Earth-like landscapes involving hydrocarbon lakes and seas as well as sand dunes and lava-like features interspersed with craters and icy mountains of hitherto unknown chemical composition. The discovery of a dynamic atmosphere and active weather system illustrates further themore » similarities between Titan and Earth. The aerosol-based haze layers, which give Titan its orange-brownish color, are not only Titan's most prominent optically visible features, but also play a crucial role in determining Titan's thermal structure and chemistry. These smog-like haze layers are thought to be very similar to those that were present in Earth's atmosphere before life developed more than 3.8 billion years ago, absorbing the destructive ultraviolet radiation from the Sun, thus acting as 'prebiotic ozone' to preserve astrobiologically important molecules on Titan. Compared to Earth, Titan's low surface temperature of 94 K and the absence of liquid water preclude the evolution of biological chemistry as we know it. Exactly because of these low temperatures, Titan provides us with a unique prebiotic 'atmospheric laboratory' yielding vital clues - at the frozen stage - on the likely chemical composition of the atmosphere of the primitive Earth. However, the underlying chemical processes, which initiate the haze formation from simple molecules, have been not understood well to date.« less

Physical conditions on the early Earth

PubMed Central

Lunine, Jonathan I

2006-01-01

The formation of the Earth as a planet was a large stochastic process in which the rapid assembly of asteroidal-to-Mars-sized bodies was followed by a more extended period of growth through collisions of these objects, facilitated by the gravitational perturbations associated with Jupiter. The Earth's inventory of water and organic molecules may have come from diverse sources, not more than 10% roughly from comets, the rest from asteroidal precursors to chondritic bodies and possibly objects near Earth's orbit for which no representative class of meteorites exists today in laboratory collections. The final assembly of the Earth included a catastrophic impact with a Mars-sized body, ejecting mantle and crustal material to form the Moon, and also devolatilizing part of the Earth. A magma ocean and steam atmosphere (possibly with silica vapour) existed briefly in this period, but terrestrial surface waters were below the critical point within 100 million years after Earth's formation, and liquid water existed continuously on the surface within a few hundred million years. Organic material delivered by comets and asteroids would have survived, in part, this violent early period, but frequent impacts of remaining debris probably prevented the continuous habitability of the Earth for one to several hundred million years. Planetary analogues to or records of this early time when life began include Io (heat flow), Titan (organic chemistry) and Venus (remnant early granites). PMID:17008213

Life Beneath Glacial Ice - Earth(!) Mars(?) Europa(?)

NASA Technical Reports Server (NTRS)

Allen, Carlton C.; Grasby, Stephen E.; Longazo, Teresa G.; Lisle, John T.; Beauchamp, Benoit

2002-01-01

We are investigating a set of cold springs that deposit sulfur and carbonate minerals on the surface of a Canadian arctic glacier. The spring waters and mineral deposits contain microorganisms, as well as clear evidence that biological processes mediate subglacial chemistry, mineralogy, and isotope fractionation . The formation of native sulphur and associated deposits are related to bacterially mediated reduction and oxidation of sulphur below the glacier. A non-volcanic, topography driven geothermal system, harboring a microbiological community, operates in an extremely cold environment and discharges through solid ice. Microbial life can thus exist in isolated geothermal refuges despite long-term subfreezing surface conditions. Earth history includes several periods of essentially total glaciation. lee in the near subsurface of Mars may have discharged liquid water in the recent past Cracks in the ice crust of Europa have apparently allowed the release of water to the surface. Chemolithotrophic bacteria, such as those in the Canadian springs, could have survived beneath the ice of "Snowball Earth", and life forms with similar characteristics might exist beneath the ice of Mars or Europa. Discharges of water from such refuges may have brought to the surface living microbes, as well as longlasting chemical, mineralogical, and isotopic indications of subsurface life.

Ultraviolet photochemistry of cyanoacetylene: Application to Titan. [Abstract only

NASA Technical Reports Server (NTRS)

Clarke, D. W.; Ferris, J. P.

1994-01-01

Cyanoacetylene is believed to have had a central role in the formation of the pyrimidines essential for RNA synthesis leading to the origin of life on Earth. Cyanoacetylene has also been detected on Titan, Saturn's largest moon, and the only moon in the solar system that possesses a dense atmosphere. It is generally accepted that photochemistry plays a major role in the formation of the complex organic molecules and aerosols found in Titan's atmosphere. Because of its long wavelength absorption and low dissociation threshold it is expected that cyanoacetylene is an important part of these photochemical processes. Since cyanoacetylene would also have been subject to ultraviolet light in the atmosphere of early Earth, an investigation of cyanoacetylene photochemistry on Titan might lead to a better understanding of both the photochemical reactions occurring on primitive earth and the processes of chemical evolution as they occur in planetary atmospheres. The effects of irradiation wavelength, mixing with Titan's atmospheric gases, reducing the temperature and lowering cyanoacetylene partial pressures on product formation and polymer composition have been determined with the ultimate goal of understanding the chemical transformations taking place in Titan's atmosphere.

Advances in Raman spectroscopy for In Situ Identification of Minerals and Organics on Diverse Planetary Surfaces: from Mars to Titan

NASA Astrophysics Data System (ADS)

Blacksberg, J.; Alerstam, E.; Maruyama, Y.; Cochrane, C.; Rossman, G. R.

2015-12-01

We present recent developments in time-resolved Raman spectroscopy for in situ planetary surface exploration, aimed at identification of both minerals and organics. Raman is a non-destructive surface technique that requires no sample preparation. Raman spectra are highly material specific and can be used for identification of a wide range of unknown samples. In combination with micro-scale imaging and point mapping, Raman spectroscopy can be used to directly interrogate rocks and regolith materials, while placing compositional analyses within a microtextural context, essential for understanding surface evolutionary pathways. Due to these unique capabilities, Raman spectroscopy is of great interest for the exploration of all rocky and icy bodies, for example Mars, Venus, the Moon, Mars' moons, asteroids, comets, Europa, and Titan. In this work, we focus on overcoming one of the most difficult challenges faced in Raman spectroscopy: interference from background fluorescence of the very minerals and organics that we wish to characterize. To tackle this problem we use time-resolved Raman spectroscopy, which separates the Raman from background processes in the time domain. This same technique also enables operation in daylight without the need for light shielding. Two key components are essential for the success of this technique: a fast solid-state detector and a short-pulse laser. Our detector is a custom developed Single Photon Avalanche Diode (SPAD) array, capable of sub-ns time-gating. Our pulsed lasers are solid-state miniature pulsed microchip lasers. We discuss optimization of laser and detector parameters for our application. We then present Raman spectra of particularly challenging planetary analog samples to demonstrate the unique capabilities of this time-resolved Raman instrument, for example, Mars-analog clays and Titan-analog organics. The research described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a

Biologically Enhanced Energy and Carbon Cycling on Titan?

NASA Astrophysics Data System (ADS)

Schulze-Makuch, Dirk; Grinspoon, David H.

2005-08-01

With the Cassini-Huygens Mission in orbit around Saturn, the large moon Titan, with its reducing atmosphere, rich organic chemistry, and heterogeneous surface, moves into the astrobiological spotlight. Environmental conditions on Titan and Earth were similar in many respects 4 billion years ago, the approximate time when life originated on Earth. Life may have originated on Titan during its warmer early history and then developed adaptation strategies to cope with the increasingly cold conditions. If organisms originated and persisted, metabolic strategies could exist that would provide sufficient energy for life to persist, even today. Metabolic reactions might include the catalytic hydrogenation of photochemically produced acetylene, or involve the recombination of radicals created in the atmosphere by ultraviolet radiation. Metabolic activity may even contribute to the apparent youth, smoothness, and high activity of Titan's surface via biothermal energy.

Biologically enhanced energy and carbon cycling on Titan?

PubMed

Schulze-Makuch, Dirk; Grinspoon, David H

2005-08-01

With the Cassini-Huygens Mission in orbit around Saturn, the large moon Titan, with its reducing atmosphere, rich organic chemistry, and heterogeneous surface, moves into the astrobiological spotlight. Environmental conditions on Titan and Earth were similar in many respects 4 billion years ago, the approximate time when life originated on Earth. Life may have originated on Titan during its warmer early history and then developed adaptation strategies to cope with the increasingly cold conditions. If organisms originated and persisted, metabolic strategies could exist that would provide sufficient energy for life to persist, even today. Metabolic reactions might include the catalytic hydrogenation of photochemically produced acetylene, or involve the recombination of radicals created in the atmosphere by ultraviolet radiation. Metabolic activity may even contribute to the apparent youth, smoothness, and high activity of Titan's surface via biothermal energy.

Mission Techniques for Exploring Saturn's icy moons Titan and Enceladus

NASA Astrophysics Data System (ADS)

Reh, Kim; Coustenis, Athena; Lunine, Jonathan; Matson, Dennis; Lebreton, Jean-Pierre; Vargas, Andre; Beauchamp, Pat; Spilker, Tom; Strange, Nathan; Elliott, John

2010-05-01

The future exploration of Titan is of high priority for the solar system exploration community as recommended by the 2003 National Research Council (NRC) Decadal Survey [1] and ESA's Cosmic Vision Program themes. Cassini-Huygens discoveries continue to emphasize that Titan is a complex world with very many Earth-like features. Titan has a dense, nitrogen atmosphere, an active climate and meteorological cycles where conditions are such that the working fluid, methane, plays the role that water does on Earth. Titan's surface, with lakes and seas, broad river valleys, sand dunes and mountains was formed by processes like those that have shaped the Earth. Supporting this panoply of Earth-like processes is an ice crust that floats atop what might be a liquid water ocean. Furthermore, Titan is rich in very many different organic compounds—more so than any place in the solar system, except Earth. The Titan Saturn System Mission (TSSM) concept that followed the 2007 TandEM ESA CV proposal [2] and the 2007 Titan Explorer NASA Flagship study [3], was examined [4,5] and prioritized by NASA and ESA in February 2009 as a mission to follow the Europa Jupiter System Mission. The TSSM study, like others before it, again concluded that an orbiter, a montgolfiѐre hot-air balloon and a surface package (e.g. lake lander, Geosaucer (instrumented heat shield), …) are very high priority elements for any future mission to Titan. Such missions could be conceived as Flagship/Cosmic Vision L-Class or as individual smaller missions that could possibly fit within NASA's New Frontiers or ESA's Cosmic Vision M-Class budgets. As a result of a multitude of Titan mission studies, several mission concepts have been developed that potentially fit within various cost classes. Also, a clear blueprint has been laid out for early efforts critical toward reducing the risks inherent in such missions. The purpose of this paper is to provide a brief overview of potential Titan (and Enceladus) mission

Titan Temperature Lag Maps

NASA Image and Video Library

2016-02-18

This sequence of maps shows varying surface temperatures on Saturn moon Titan at two-year intervals, from 2004 to 2016. The measurements were made by the Composite Infrared Spectrometer CIRS instrument on NASA Cassini spacecraft. The maps show thermal infrared radiation (heat) coming from Titan's surface at a wavelength of 19 microns, a spectral window at which the moon's otherwise opaque atmosphere is mostly transparent. Temperatures have been averaged around the globe from east to west (longitudinally) to emphasize the seasonal variation across latitudes (from north to south). Black regions in the maps are areas for which there was no data. Titan's surface temperature changes slowly over the course of the Saturn system's long seasons, which each last seven and a half years. As on Earth, the amount of sunlight received at each latitude varies as the sun's illumination moves northward or southward over the course of the 30-year-long Saturnian year. When Cassini arrived at Saturn in 2004, Titan's southern hemisphere was in late summer and was therefore the warmest region. Shortly after the 2009 equinox, in 2010, temperatures were symmetrical across the northern and southern hemispheres, mimicking the distribution observed by Voyager 1 in 1980 (one Titan year earlier). Temperatures subsequently cooled in the south and rose in the north, as southern winter approached. While the overall trend in the temperature shift is clearly evident in these maps, there is narrow banding in several places that is an artifact of making the observations through Titan's atmosphere. The moon's dense, hazy envelope adds noise to the difficult measurement. Although it moves in latitude, the maximum measured temperature on Titan remains around -292 degrees Fahrenheit (-179.6 degrees Celsius, 93.6 Kelvin), with a minimum temperature at the winter pole only 6 degrees Fahrenheit (3.5 degrees Celsius or Kelvin) colder. This is a much smaller contrast than exists between Earth's warmest and

The astrobiology of Titan

NASA Astrophysics Data System (ADS)

Raulin, F.; Coll, P.; Cabane, M.; Hebrard, E.; Israel, G.; Nguyen, M.-J.; Szopa, C.; Gpcos Team

Largest satellite of Saturn and the only satellite in the solar system having a dense atmosphere, Titan is one of the key planetary bodies for astrobiological studies, due to several aspects: Its analogies with planet Earth, in spite of much lower temperatures, The Cassini-Huygens data have largely confirmed the many analogies between Titan and our own planet. Both have similar vertical temperature profiles, (although much colder, of course, on Titan). Both have condensable and non condensable greenhouse gases in their atmosphere. Both are geologically very active. Furthermore, the data also suggest strongly the presence of a methane cycle on Titan analogous to the water cycle on Earth. The presence of an active organic chemistry, involving several of the key compounds of prebiotic chemistry. The recent data obtained from the Huygens instruments show that the organic matter in Titan low atmosphere (stratosphere and troposphere) is mainly concentrated in the aerosol particles. Because of the vertical temperature profile in this part of the atmosphere, most of the volatile organics are probably mainly condensed on the aerosol particles. The nucleus of these particles seems to be made of complex macromolecular organic matter, well mimicked in the laboratory by the "Titan's tholins". Now, laboratory tholins are known to release many organic compounds of biological interest, such as amino acids and purine and pyrimidine bases, when they are in contact with liquid water. Such hydrolysis may have occurred on the surface of Titan, in the bodies of liquid water which episodically may form on Titan's surface from meteoritic and cometary impacts. The formation of biologically interesting compounds may also occur in the deep water ocean, from the hydrolysis of complex organic material included in the chrondritic matter accreted during the formation of Titan. The possible emergence and persistence of Life on Titan 1 All ingredients which seems necessary for Life are present on

Atmospheric heat engines on earth and Mars

NASA Astrophysics Data System (ADS)

Philip, J. R.

1987-06-01

The character of the earth's atmospheric heat engine depends, inter alia, on the relatively tight linkage between surface fluxes of energy and of H2O. On Mars, on the other hand, H2O-based latent heat fluxes are only a trivial fraction of total surface energy fluxes, and the dominant component of the working fluid is CO2. These considerations are made quantitative through evaluation of Lambda, the equivalent temperature excess at the surface for a particular component of the working fluid. The very different values (and latitudinal distribution) of Lambda on the two planets signalize vividly their different meteorology. Preliminary study of the climatology of Lambda on earth brings out, in particular, the tightness of the H2O-energy linkage in the tropics.

Is Mars a habitable environment for extremophilic microorganisms from Earth?

NASA Astrophysics Data System (ADS)

Rettberg, Petra; Reitz, Guenther; Flemming, Hans-Curt; Bauermeister, Anja

In the last decades several sucessful space missions to our neighboring planet Mars have deepened our knowledge about its environmental conditions substantially. Orbiters with intruments for remote sensing and landers with sophisticated intruments for in situ investigations resulted in a better understanding of Mars’ radiation climate, atmospheric composition, geology, and mineralogy. Extensive regions of the surface of Mars are covered with sulfate- and ferric oxide-rich layered deposits. These sediments indicate the possible existence of aqueous, acidic environments on early Mars. Similar environments on Earth harbour a specialised community of microorganisms which are adapted to the local stress factors, e.g. low pH, high concentrations of heavy metal ions, oligotrophic conditions. Acidophilic iron-sulfur bacteria isolated from such habitats on Earth could be considered as model organisms for an important part of a potential extinct Martian ecosystem or an ecosystem which might even exist today in protected subsurface niches. Acidithiobacillus ferrooxidans was chosen as a model organism to study the ability of these bacteria to survive or grow under conditions resembling those on Mars. Stress conditions tested included desiccation, radiation, low temperatures, and high salinity. It was found that resistance to desiccation strongly depends on the mode of drying. Biofilms grown on membrane filters can tolerate longer periods of desiccation than planktonic cells dried without any added protectants, and drying under anaerobic conditions is more favourable to survival than drying in the presence of oxygen. Organic compounds such as trehalose and glycine betaine had a positive influence on survival after drying and freezing. A. ferrooxidans was shown to be sensitive to high salt concentrations, ionizing radiation, and UV radiation. However, the bacteria were able to utilize the iron minerals in Mars regolith mixtures as sole energy source. The survival and growth of

Biota and Biomolecules in Extreme Environments on Earth: Implications for Life Detection on Mars

PubMed Central

Aerts, Joost W.; Röling, Wilfred F.M.; Elsaesser, Andreas; Ehrenfreund, Pascale

2014-01-01

The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids) occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to their indispensability for life on Earth, these biomarkers are also prime targets in the search for life on Mars. Biomarkers degrade over time; in situ environmental conditions influence the preservation of those molecules. Nonetheless, upon shielding (e.g., by mineral surfaces), particular biomarkers can persist for billions of years, making them of vital importance in answering questions about the origins and limits of life on early Earth and Mars. The search for organic material and biosignatures on Mars is particularly challenging due to the hostile environment and its effect on organic compounds near the surface. In support of life detection on Mars, it is crucial to investigate analogue environments on Earth that resemble best past and present Mars conditions. Terrestrial extreme environments offer a rich source of information allowing us to determine how extreme conditions affect life and molecules associated with it. Extremophilic organisms have adapted to the most stunning conditions on Earth in environments with often unique geological and chemical features. One challenge in detecting biomarkers is to optimize extraction, since organic molecules can be low in abundance and can strongly adsorb to mineral surfaces. Methods and analytical tools in the field of life science are continuously improving. Amplification methods are very useful for the detection of low concentrations of genomic material but most other organic molecules are not prone to amplification methods. Therefore, a great deal depends on the extraction efficiency. The questions “what to look for”, “where to look”, and “how to look for it�

Biota and biomolecules in extreme environments on Earth: implications for life detection on Mars.

PubMed

Aerts, Joost W; Röling, Wilfred F M; Elsaesser, Andreas; Ehrenfreund, Pascale

2014-10-13

The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids) occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to their indispensability for life on Earth, these biomarkers are also prime targets in the search for life on Mars. Biomarkers degrade over time; in situ environmental conditions influence the preservation of those molecules. Nonetheless, upon shielding (e.g., by mineral surfaces), particular biomarkers can persist for billions of years, making them of vital importance in answering questions about the origins and limits of life on early Earth and Mars. The search for organic material and biosignatures on Mars is particularly challenging due to the hostile environment and its effect on organic compounds near the surface. In support of life detection on Mars, it is crucial to investigate analogue environments on Earth that resemble best past and present Mars conditions. Terrestrial extreme environments offer a rich source of information allowing us to determine how extreme conditions affect life and molecules associated with it. Extremophilic organisms have adapted to the most stunning conditions on Earth in environments with often unique geological and chemical features. One challenge in detecting biomarkers is to optimize extraction, since organic molecules can be low in abundance and can strongly adsorb to mineral surfaces. Methods and analytical tools in the field of life science are continuously improving. Amplification methods are very useful for the detection of low concentrations of genomic material but most other organic molecules are not prone to amplification methods. Therefore, a great deal depends on the extraction efficiency. The questions "what to look for", "where to look", and "how to look for it" require more of

Geomorphic Mapping of Lava Flows on Mars, Earth, and Mercury

NASA Astrophysics Data System (ADS)

Golder, K. B.; Burr, D. M.

2018-06-01

To advance understanding of flood basalts, we have mapped lava flows on three planets, Mars, Earth, and Mercury, as part of three projects. The common purpose of each project is to investigate potential magma sources and/or emplacement conditions.

Reducing greenhouses and the temperature history of earth and Mars

NASA Technical Reports Server (NTRS)

Sagan, C.

1977-01-01

It has been suggested that NH3 and other reducing gases were present in the earth's primitive atmosphere, enhancing the global greenhouse effect; data obtained through isotopic archeothermometry support this hypothesis. Computations have been applied to the evolution of surface temperatures on Mars, considering various bolometric albedos and compositions. The results are of interest in the study of Martian sinuous channels which may have been created by aqueous fluvial errosion, and imply that clement conditions may have previously occurred on Mars, and may occur in the future.

A Passive Earth-Entry Capsule for Mars Sample Return

NASA Technical Reports Server (NTRS)

Mitcheltree, Robert A.; Kellas, Sotiris

1999-01-01

A combination of aerodynamic analysis and testing, aerothermodynamic analysis, structural analysis and testing, impact analysis and testing, thermal analysis, ground characterization tests, configuration packaging, and trajectory simulation are employed to determine the feasibility of an entirely passive Earth entry capsule for the Mars Sample Return mission. The design circumvents the potential failure modes of a parachute terminal descent system by replacing that system with passive energy absorbing material to cushion the Mars samples during ground impact. The suggested design utilizes a spherically blunted 45-degree half-angle cone forebody with an ablative heat shield. The primary structure is a hemispherical, composite sandwich enclosing carbon foam energy absorbing material. Though no demonstration test of the entire system is included, results of the tests and analysis presented indicate that the design is a viable option for the Mars Sample Return Mission.

Titan Airship Surveyor

NASA Technical Reports Server (NTRS)

Kerzhanovich, V.; Yavrouian, A.; Cutts, J.; Colozza, A.; Fairbrother, D.

2001-01-01

Saturn's moon Titan is considered to be one of the prime candidates for studying prebiotic materials - the substances that precede the formation of life but have disappeared from the Earth as a result of the evolution of life. A unique combination of a dense, predominantly nitrogen, atmosphere (more than four times that of the Earth), low gravity (six times less than on the Earth) and small temperature variations makes Titan the almost ideal planet for studies with lighter-than-air aerial platforms (aerobots). Moreover, since methane clouds and photochemical haze obscure the surface, low-altitude aerial platforms are the only practical means that can provide global mapping of the Titan surface at visible and infrared wavelengths. One major challenge in Titan exploration is the extremely cold atmosphere (approx. 90 K). However, current material technology the capability to operate aerobots at these very low temperatures. A second challenge is the remoteness from the Sun (10 AU) that makes the nuclear (radioisotopic) energy the only practical source of power. A third challenge is remoteness from the Earth (approx. 10 AU, two-way light-time approx. 160 min) which imposes restrictions on data rates and makes impractical any meaningful real-time control. A small-size airship (approx. 25 cu m) can carry a payload approximately 100 kg. A Stirling engine coupled to a radioisotope heat source would be the prime choice for producing both mechanical and electrical power for sensing, control, and communications. The cold atmospheric temperature makes Stirling machines especially effective. With the radioisotope power source the airship may fly with speed approximately 5 m/s for a year or more providing an excellent platform for in situ atmosphere measurements and a high-resolution remote sensing with unlimited access on a global scale. In a station-keeping mode the airship can be used for in situ studies on the surface by winching down an instrument package. Floating above the

Waves on Seas of Mars and Titan: Wind-Tunnel Experiments on Wind-Wave Generation in Extraterrestrial Atmospheres

NASA Technical Reports Server (NTRS)

Lorenz, R. D.; Kraal, E. R.; Eddlemon, E. E.; Cheney, J.; Greeley, R.

2004-01-01

The generation of waves by winds across Earth's water oceans is a topic of enduring fascination. However, the physics of the problem are rather forbidding and thus the relationships between real-world windspeed and sea state tend to be empirical. Such empirical relations are of limited utility in environments where the physical parameters are different, such as the surfaces of other planets. These environments have only recently come to oceanographers attention, with the discovery of ancient shorelines and lakes on Mars, and the prospects for and recent evidence of lakes and seas of liquid hydrocarbons on Saturn's moon Titan. We are aware of only one other published experimental wind-water tunnel study where the fluid parameters have been varied. This used artificially-generated mm-scale waves at 3.8-7.6 Hz in water, glycerol solutions (higher viscosity) and surfactant solutions (lower surface tension). Lower viscosity solutions had higher wave growth rates: surprisingly, higher surface tension led to more rapid wave growth. The liquid density was not appreciably varied, and 1 bar air was used throughout.We used the MARSWIT (Mars Wind Tunnel) operated by ASU at NASA Ames. A fiberglass tray (5 cm x 120 cm x 75 cm) was installed in the tunnel, with an approx. 1:5 ramp to prevent strong flow separation. The tray was filled to a depth of about 4 cm. Sensors were clamped to the tray itself or held by a steel and aluminium frame just above the water level. A towel was draped on the water surface at the downwind end of the tray to act as a damper to suppress wave reflection. Position-sensitive infrared (IR) reflection sensors (Sharp GP12D02) and ultrasonic rangers (Devantech DF-04) used in mobile robotics were used as water level sensors. The tray was observed with a video camera, whose output could be viewed on a monitor and recorded on VHS tape.

Access to Mars from Earth-Moon Libration Point Orbits:. [Manifold and Direct Options

NASA Technical Reports Server (NTRS)

Kakoi, Masaki; Howell, Kathleen C.; Folta, David

2014-01-01

This investigation is focused specifically on transfers from Earth-Moon L(sub 1)/L(sub 2) libration point orbits to Mars. Initially, the analysis is based in the circular restricted three-body problem to utilize the framework of the invariant manifolds. Various departure scenarios are compared, including arcs that leverage manifolds associated with the Sun-Earth L(sub 2) orbits as well as non-manifold trajectories. For the manifold options, ballistic transfers from Earth-Moon L(sub 2) libration point orbits to Sun-Earth L(sub 1)/L(sub 2) halo orbits are first computed. This autonomous procedure applies to both departure and arrival between the Earth-Moon and Sun-Earth systems. Departure times in the lunar cycle, amplitudes and types of libration point orbits, manifold selection, and the orientation/location of the surface of section all contribute to produce a variety of options. As the destination planet, the ephemeris position for Mars is employed throughout the analysis. The complete transfer is transitioned to the ephemeris model after the initial design phase. Results for multiple departure/arrival scenarios are compared.

Acetylene fermentation: An Earth-based analog of biological carbon cycling on Titan

NASA Astrophysics Data System (ADS)

Miller, L. G.; Baesman, S. M.; Hoeft, S. E.; Kirshtein, J.; Wolf, K.; Voytek, M. A.; Oremland, R. S.

2009-12-01

Acetylene (C2H2) is present in part per million quantities in the atmosphere of Titan; conceivably as an intermediate product of methane photolysis. Currently, Earth’s atmosphere contains only trace amounts of C2H2 (~40 pptv), however higher concentrations likely prevailed during the Hadean and early Archean eons (4.5 - 3.5 Ga). We isolated C2H2-fermenting microbes from various aquatic and sedimentary environments. Acetylene fermentation proceeds via acetylene hydratase (AH) through acetaldehyde, which dismutates to ethanol and acetate, and if oxidants are present (e.g., sulfate) eventually to CO2. Thus, the remnants of a C2H2 cycle exists today on Earth but may also occur on Titan and/or Enceladus, both being planetary bodies hypothesized to have liquid water underlying their frozen surfaces. We developed a molecular method for AH by designing PCR primers to target the functional gene in Pelobacter acetylenicus. We used this method to scan new environments for the presence of AH and we employed DNA sequencing of the 16S rRNA gene in order to positively identify pelobacters in environmental samples. Acetylene fermentation was documented in five diverse salt-, fresh-, and ground-water sites. Pelobacter was identified as the genus responsible for acetylene fermentation in some, but not all, of these sites. Successful probing for AH preceded the discovery of acetylene consumption in a contaminated groundwater site, demonstrating the utility of functional gene probing. A pure culture of a C2H2-fermenting pelobacter was obtained from an intertidal mudflat. We also obtained an enrichment culture (co-cultured with a sulfate reducer) from freshwater lake sediments, but neither was pelobacter nor AH detected in this sample, suggesting that an alternative pathway may be involved here. Slurry experiments using these lake sediments either with or without added C2H2 or sulfate showed that sulfate reduction and acetylene fermentation were independent processes. In general, the

Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins

USGS Publications Warehouse

Cartwright, R.; Clayton, J.A.; Kirk, R.L.

2011-01-01

Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (Rb) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have Rb values greater than the expected range (3.0-5.0) for dendritic networks; comparisons with Rb values determined for Titan basins, in conjunction with similarities in network patterns, suggest that portions of Titan's north polar region are modified by tectonic forces. Sufficient elevation data existed to calculate bed slope and potential fluvial sediment transport rates in at least one Titan basin, indicating that 75mm water ice grains (observed at the Huygens landing site) should be readily entrained given sufficient flow depths of liquid hydrocarbons. Volumetric sediment transport estimates suggest that ???6700-10,000 Titan years (???2.0-3.0??105 Earth years) are required to erode this basin to its minimum relief (assuming constant 1m and 1.5m flows); these lowering rates increase to ???27,000-41,000 Titan years (???8.0-12.0??105 Earth years) when flows in the north polar region are restricted to summer months. ?? 2011 Elsevier Inc.

The Exploration of Titan and the Saturnian System

NASA Astrophysics Data System (ADS)

Coustenis, Athena

The exploration of the outer solar system and in particular of the giant planets and their environments is an on-going process with the Cassini spacecraft currently around Saturn, the Juno mission to Jupiter preparing to depart and two large future space missions planned to launch in the 2020-2025 time frame for the Jupiter system and its satellites (Europa and Ganymede) on the one hand, and the Saturnian system and Titan on the other hand [1,2]. Titan, Saturn's largest satellite, is the only other object in our Solar system to possess an extensive nitrogen atmosphere, host to an active organic chemistry, based on the interaction of N2 with methane (CH4). Following the Voyager flyby in 1980, Titan has been intensely studied from the ground-based large telescopes (such as the Keck or the VLT) and by artificial satellites (such as the Infrared Space Observatory and the Hubble Space Telescope) for the past three decades. Prior to Cassini-Huygens, Titan's atmospheric composition was thus known to us from the Voyager missions and also through the explorations by the ISO. Our perception of Titan had thus greatly been enhanced accordingly, but many questions remained as to the nature of the haze surrounding the satellite and the composition of the surface. The recent revelations by the Cassini-Huygens mission have managed to surprise us with many discoveries [3-8] and have yet to reveal more of the interesting aspects of the satellite. The Cassini-Huygens mission to the Saturnian system has been an extraordinary success for the planetary community since the Saturn-Orbit-Insertion (SOI) in July 2004 and again the very successful probe descent and landing of Huygens on January 14, 2005. One of its main targets was Titan. Titan was revealed to be a complex world more like the Earth than any other: it has a dense mostly nitrogen atmosphere and active climate and meteorological cycles where the working fluid, methane, behaves under Titan conditions the way that water does on

The Earth and Moon As Seen by 2001 Mars Odyssey's Thermal Emission Imaging System

NASA Technical Reports Server (NTRS)

2001-01-01

2001 Mars Odyssey's Thermal Emission Imaging System (THEMIS) took this portrait of the Earth and its companion Moon, using the infrared camera, one of two cameras in the instrument. It was taken at a distance of 3,563,735 kilometers (more than 2 million miles) on April 19, 2001 as the 2001 Mars Odyssey spacecraft left the Earth. From this distance and perspective the camera was able to acquire an image that directly shows the true distance from the Earth to the Moon. The Earth's diameter is about 12,750 km, and the distance from the Earth to the Moon is about 385,000 km, corresponding to 30 Earth diameters. The dark region seen on Earth in the infrared temperature image is the cold south pole, with a temperature of minus 50 degrees Celsius (minus 58 degrees Fahrenheit). The small bright region above it is warm Australia. This image was acquired using the 9.1 um infrared filter, one of nine filters that the instrument will use to map the mineral composition and temperature of the martian surface. From this great distance, each picture element (pixel) in the image corresponds to a region 900 by 900 kilometers or greater in size or about size of the state of Texas. Once Odyssey reaches Mars orbit each infrared pixel will cover a region only 100 by 100 meters on the surface, about the size of a major league baseball field.

Development of a model to compute the extension of life supporting zones for Earth-like exoplanets.

PubMed

Neubauer, David; Vrtala, Aron; Leitner, Johannes J; Firneis, Maria G; Hitzenberger, Regina

2011-12-01

A radiative convective model to calculate the width and the location of the life supporting zone (LSZ) for different, alternative solvents (i.e. other than water) is presented. This model can be applied to the atmospheres of the terrestrial planets in the solar system as well as (hypothetical, Earth-like) terrestrial exoplanets. Cloud droplet formation and growth are investigated using a cloud parcel model. Clouds can be incorporated into the radiative transfer calculations. Test runs for Earth, Mars and Titan show a good agreement of model results with observations.

Comparison of the distribution of large magmatic centers on Earth, Venus, and Mars

NASA Technical Reports Server (NTRS)

Crumpler, L. S.

1993-01-01

Volcanism is widely distributed over the surfaces of the major terrestrial planets: Venus, Earth, and Mars. Anomalous centers of magmatic activity occur on each planet and are characterized by evidence for unusual concentrations of volcanic centers, long-lived activity, unusual rates of effusion, extreme size of volcanic complexes, compositionally unusual magmatism, and evidence for complex geological development. The purpose of this study is to compare the characteristics and distribution of these magmatic anomalies on Earth, Venus, and Mars in order to assess these characteristics as they may relate to global characteristics and evolution of the terrestrial planets.

Ablative Heat Shield Studies for NASA Mars/Earth Return Entry Vehicles

DTIC Science & Technology

1990-09-01

RETURN ENTRY VEHICLES by Michael K. Hamm September, 1990 NASA Thesis Advisor: William D. Henline Thesis Co-Advisor: Max F. Platzer Approved for public...STUDIES FOR NASA MARS/EARTH RETURN ENTRY VEHICLES (UNCLASSIFIED) 12. PERSONAL AUTHOR(S) Harm, Michael, K. 13a TYPE OF REPORT 13b TIME COVERED 14 DATE OF...theoretical values. The tests were performed to ascertain if RSI type materials could be used for entry vehicles proposed in NASA Mars missions. 20

Earth-Mars Telecommunications and Information Management System (TIMS): Antenna Visibility Determination, Network Simulation, and Management Models

NASA Technical Reports Server (NTRS)

Odubiyi, Jide; Kocur, David; Pino, Nino; Chu, Don

1996-01-01

This report presents the results of our research on Earth-Mars Telecommunications and Information Management System (TIMS) network modeling and unattended network operations. The primary focus of our research is to investigate the feasibility of the TIMS architecture, which links the Earth-based Mars Operations Control Center, Science Data Processing Facility, Mars Network Management Center, and the Deep Space Network of antennae to the relay satellites and other communication network elements based in the Mars region. The investigation was enhanced by developing Build 3 of the TIMS network modeling and simulation model. The results of several 'what-if' scenarios are reported along with reports on upgraded antenna visibility determination software and unattended network management prototype.

Autonomous Mars ascent and orbit rendezvous for earth return missions

NASA Technical Reports Server (NTRS)

Edwards, H. C.; Balmanno, W. F.; Cruz, Manuel I.; Ilgen, Marc R.

1991-01-01

The details of tha assessment of autonomous Mars ascent and orbit rendezvous for earth return missions are presented. Analyses addressing navigation system assessments, trajectory planning, targeting approaches, flight control guidance strategies, and performance sensitivities are included. Tradeoffs in the analysis and design process are discussed.

Comparative habitability of the Earth, Venus and Mars in the young solar system.

NASA Astrophysics Data System (ADS)

Nisbet, E. G.

2008-09-01

Abstract To be habitable, a planet must be suitable at all scales [1]. The setting in relation to the star must be right, so that surface temperatures can sustain liquid water. The planetary inventory must be suitable, providing surface water, rocks, and accessible thermodynamic disequilibrium. There must be physical habitat, especially mud and hydrothermal systems around volcanoes. Planets are not static: they evolve. Habitability must evolve with the planet. On accretion, the processes of impact and formation of volatile inventory must be suitable. Tectonics and volcanism must supply redox contrasts and biochemical substrates capable not only of starting life but of sustaining it. Mud or soft sediment may be essential: it is unlikely that early life can sustain itself in open water or air. This requirement for mud has tectonic implications. Once life starts, it immediately alters its own environment, by consuming nutrient. Until photosynthesis evolves, inorganic sources must supply sustained redox contrast to the local environment. But life changes its setting, both by risky alterations to the atmospheric greenhouse (drawing down CO2, emitting CH4), and by partitioning reductants (e.g. as dead bodies) and oxidants (waste). Somehow the planet must avoid both freezing and boiling. Early in the history of the solar system, a passing galactic tourist might have rated Venus as the likeliest habitat for life, Mars next, and Earth last of the three. Venus was warm and hospitable, Mars clement, and Earth had been though an impact episode powerful enough to make a silicate atmosphere. By comparison with Earth there are many potential environmental settings on Mars in which life may once have occurred, or may even continue to exist. Perhaps Mars seeded earth? Yet today the reverse order of habitability is the case. Earth today is safeguarded by a reworked atmosphere that is 99% of biological construction, maintained in active disequilibrium with the surface. Mars, in

Cratering on Titan: A Pre-Cassini Perspective

NASA Technical Reports Server (NTRS)

Lorenz, R. D.

1997-01-01

The NASA-ESA Cassini mission, comprising a formidably instrumented orbiter and parachute-borne probe to be launched this October, promises to reveal a crater population on Titan that has been heretofore hidden by atmospheric haze. This population on the largest remaining unexplored surface in the solar system will be invaluable in comparative planetological studies, since it introduces evidence of the atmospheric effects of cratering on an icy satellite. Here, I highlight some impact features we may hope to find and could devote some modeling effort toward. Titan in a Nutshell: Radius= 2575 km. Density= 1880 kg/cubic m consistent with rock-ice composition. Surface pressure = 1.5 bar. Surface gravity = 1.35 m/square s Atmosphere -94% N2 6% CH, Surface temperature = 94K Tropopause temperature = 70K at 40 km alt. Probable liquid hydrocarbon deposits exist on or near the surface.Titan in a Nutshell: Radius= 2575 km. Density= 1880 kg/cubic m consistent with rock-ice composition. Surface pressure = 1.5 bar. Surface gravity = 1.35 m/square s; Atmosphere about 94% N2 6% CH, Surface temperature = 94K Tropopause temperature = 70K at 40 km alt. Probable liquid hydrocarbon deposits exist on or near the surface. Titan is comparable to Callisto and Ganymede for strength/gravity, Mars/Earth/Venus for atmospheric interaction, and Hyperion, Rhea, and Iapetus for impactor distribution. The leading/trailing asymmetry of crater density from heliocentric impactors is expected to be about 5-6, in the absence of resurfacing. Any Saturnocentric impactor population is likely to alter this. In particular the impact disruption of Hyperion is noted; because of the 3:4 orbital resonance with Titan, fragments from the proto-Hyperion breakup would have rapidly accreted onto Titan. Titan's resurfacing history is of course unknown. The disruption of impactors into fragments that individually create small craters is expected to occur. A crude estimate suggests a maximum separation of about 2 km

Cratering on Titan: A Pre-Cassini Perspective

NASA Astrophysics Data System (ADS)

Lorenz, R. D.

1997-01-01

The NASA-ESA Cassini mission, comprising a formidably instrumented orbiter and parachute-borne probe to be launched this October, promises to reveal a crater population on Titan that has been heretofore hidden by atmospheric haze. This population on the largest remaining unexplored surface in the solar system will be invaluable in comparative planetological studies, since it introduces evidence of the atmospheric effects of cratering on an icy satellite. Here, I highlight some impact features we may hope to find and could devote some modeling effort toward. Titan in a Nutshell: Radius= 2575 km. Density= 1880 kg/cubic m consistent with rock-ice composition. Surface pressure = 1.5 bar. Surface gravity = 1.35 m/square s Atmosphere -94% N2 6% CH, Surface temperature = 94K Tropopause temperature = 70K at 40 km alt. Probable liquid hydrocarbon deposits exist on or near the surface.Titan in a Nutshell: Radius= 2575 km. Density= 1880 kg/cubic m consistent with rock-ice composition. Surface pressure = 1.5 bar. Surface gravity = 1.35 m/square s; Atmosphere about 94% N2 6% CH, Surface temperature = 94K Tropopause temperature = 70K at 40 km alt. Probable liquid hydrocarbon deposits exist on or near the surface. Titan is comparable to Callisto and Ganymede for strength/gravity, Mars/Earth/Venus for atmospheric interaction, and Hyperion, Rhea, and Iapetus for impactor distribution. The leading/trailing asymmetry of crater density from heliocentric impactors is expected to be about 5-6, in the absence of resurfacing. Any Saturnocentric impactor population is likely to alter this. In particular the impact disruption of Hyperion is noted; because of the 3:4 orbital resonance with Titan, fragments from the proto-Hyperion breakup would have rapidly accreted onto Titan. Titan's resurfacing history is of course unknown. The disruption of impactors into fragments that individually create small craters is expected to occur. A crude estimate suggests a maximum separation of about 2 km

Titan's organic chemistry: Results of simulation experiments

NASA Technical Reports Server (NTRS)

Sagan, Carl; Thompson, W. Reid; Khare, Bishun N.

1992-01-01

Recent low pressure continuous low plasma discharge simulations of the auroral electron driven organic chemistry in Titan's mesosphere are reviewed. These simulations yielded results in good accord with Voyager observations of gas phase organic species. Optical constants of the brownish solid tholins produced in similar experiments are in good accord with Voyager observations of the Titan haze. Titan tholins are rich in prebiotic organic constituents; the Huygens entry probe may shed light on some of the processes that led to the origin of life on Earth.

Mega-geomorphology: Mars vis a vis Earth

NASA Technical Reports Server (NTRS)

Sharp, R. P.

1985-01-01

The areas of chaotic terrain, the giant chasma of the Valles Marineris region, the complex linear and circular depressions of Labyrinthus Noctis on Mars all suggest the possibility of large scale collapse of parts of the martian crust within equatorial and sub equatorial latitudes. It seems generally accepted that the above features are fossil, being perhaps, more than a billion years old. It is possible that parts of Earth's crust experienced similar episodes of large scale collapse sometime early in the evolution of the planet.

Atmospheric Models for Aeroentry and Aeroassist

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

2005-01-01

Eight destinations in the Solar System have sufficient atmosphere for aeroentry, aeroassist, or aerobraking/aerocapture: Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, plus Saturn's moon Titan. Engineering-level atmospheric models for Earth, Mars, Titan, and Neptune have been developed for use in NASA's systems analysis studies of aerocapture applications. Development has begun on a similar atmospheric model for Venus. An important capability of these models is simulation of quasi-random perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithms, and for thermal systems design. Characteristics of these atmospheric models are compared, and example applications for aerocapture are presented. Recent Titan atmospheric model updates are discussed, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Probe entry at Titan. Recent and planned updates to the Mars atmospheric model, in support of future Mars aerocapture systems analysis studies, are also presented.

Atmospheric Models for Aeroentry and Aeroassist

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

2004-01-01

Eight destinations in the Solar System have sufficient atmosphere for aeroentry, aeroassist, or aerobraking/aerocapture: Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, plus Saturn's moon Titan. Engineering-level atmospheric models for Earth, Mars, Titan, and Neptune have been developed for use in NASA s systems analysis studies of aerocapture applications. Development has begun on a similar atmospheric model for Venus. An important capability of these models is simulation of quasi-random perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithms, and for thermal systems design. Characteristics of these atmospheric models are compared, and example applications for aerocapture are presented. Recent Titan atmospheric model updates are discussed, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Probe entry at Titan. Recent and planned updates to the Mars atmospheric model, in support of future Mars aerocapture systems analysis studies, are also presented.

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.

2001 Mars Odyssey Images Earth (Visible and Infrared)

NASA Technical Reports Server (NTRS)

2001-01-01

2001 Mars Odyssey's Thermal Emission Imaging System (THEMIS) acquired these images of the Earth using its visible and infrared cameras as it left the Earth. The visible image shows the thin crescent viewed from Odyssey's perspective. The infrared image was acquired at exactly the same time, but shows the entire Earth using the infrared's 'night-vision' capability. Invisible light the instrument sees only reflected sunlight and therefore sees nothing on the night side of the planet. In infrared light the camera observes the light emitted by all regions of the Earth. The coldest ground temperatures seen correspond to the nighttime regions of Antarctica; the warmest temperatures occur in Australia. The low temperature in Antarctica is minus 50 degrees Celsius (minus 58 degrees Fahrenheit); the high temperature at night in Australia 9 degrees Celsius(48.2 degrees Fahrenheit). These temperatures agree remarkably well with observed temperatures of minus 63 degrees Celsius at Vostok Station in Antarctica, and 10 degrees Celsius in Australia. The images were taken at a distance of 3,563,735 kilometers (more than 2 million miles) on April 19,2001 as the Odyssey spacecraft left Earth.

Automated Mars surface sample return mission concepts for achievement of essential scientific objectives

NASA Technical Reports Server (NTRS)

Weaver, W. L.; Norton, H. N.; Darnell, W. L.

1975-01-01

Mission concepts were investigated for automated return to Earth of a Mars surface sample adequate for detailed analyses in scientific laboratories. The minimum sample mass sufficient to meet scientific requirements was determined. Types of materials and supporting measurements for essential analyses are reported. A baseline trajectory profile was selected for its low energy requirements and relatively simple implementation, and trajectory profile design data were developed for 1979 and 1981 launch opportunities. Efficient spacecraft systems were conceived by utilizing existing technology where possible. Systems concepts emphasized the 1979 launch opportunity, and the applicability of results to other opportunities was assessed. It was shown that the baseline missions (return through Mars parking orbit) and some comparison missions (return after sample transfer in Mars orbit) can be accomplished by using a single Titan III E/Centaur as the launch vehicle. All missions investigated can be accomplished by use of Space Shuttle/Centaur vehicles.

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

NASA Technical Reports Server (NTRS)

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

2015-01-01

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

Titan - a New Laboratory for Oceanography

NASA Astrophysics Data System (ADS)

Lorenz, R. D.

2001-12-01

Saturn's giant moon Titan has a thick (1.5 bar) nitrogen atmosphere, and quite probably large expanses of liquid hydrocarbons on its surface. The physical processes in these lakes and seas will open new vistas on oceanography and limnology. Although the Voyager-era paradigm of a deep, global ocean is ruled out by radar and infrared data showing that at least part of Titan's surface is icy, the photochemical arguments that originally led to the proposal of hydrocarbon oceans still apply. Even if the methane in the atmosphere is being resupplied by delivery from the interior, the ethane produced by photolysis would still accumulate to form large deposits on the surface. The near-infrared maps of Titan's surface from the Hubble Space Telescope and groundbased adaptive optics consistently show a number of dark (in fact, pitch-black!) regions that are strong candidates for hydrocarbon seas. These could be up to some 500km in extent. Titan promises to be a new laboratory for oceanography. Like in meteorology, many ocean processes are better parameterized than they are understood, and thus the different physical circumstances on Titan may shed new light on them. Titan has a lower gravity and its ocean fluids are of lower density, perhaps of lower viscosity (depending on solutes and suspended material) and probably rather more likely to cavitate. The ratio of atmospheric density to ocean density is much larger on Titan than on Earth, suggesting that liquid motions will be well-coupled to surface winds (although the distance from the sun is such that the energy in such winds is likely to be low.) Titan is also subject to strong tidal forces (the equilibrium tide due to Saturn's gravity is some 400x larger than that of the moon on Earth.) Although the 100m tidal bulge stays almost fixed because Titan rotates synchronously, the eccentricity of Titan's orbit leads to significant libration and variation in the tidal strength. The 500km seas allowed by the IR data may yet have a

Simulations of Prebiotic Chemistry under Post-Impact Conditions on Titan.

PubMed

Turse, Carol; Leitner, Johannes; Firneis, Maria; Schulze-Makuch, Dirk

2013-12-17

The problem of how life began can be considered as a matter of basic chemistry. How did the molecules of life arise from non-biological chemistry? Stanley Miller's famous experiment in 1953, in which he produced amino acids under simulated early Earth conditions, was a huge leap forward in our understanding of this problem. Our research first simulated early Earth conditions based on Miller's experiment and we then repeated the experiment using Titan post-impact conditions. We simulated conditions that could have existed on Titan after an asteroid strike. Specifically, we simulated conditions after a potential strike in the subpolar regions of Titan that exhibit vast methane-ethane lakes. If the asteroid or comet was of sufficient size, it would also puncture the icy crust and bring up some of the subsurface liquid ammonia-water mixture. Since, O'Brian, Lorenz and Lunine showed that a liquid water-ammonia body could exist between about 102-104 years on Titan after an asteroid impact we modified our experimental conditions to include an ammonia-water mixture in the reaction medium. Here we report on the resulting amino acids found using the Titan post-impact conditions in a classical Miller experimental reaction set-up and how they differ from the simulated early Earth conditions.

Polygon Patterned Ground on Mars and on Earth

NASA Technical Reports Server (NTRS)

2008-01-01

Some high-latitude areas on Mars (left) and Earth (right) exhibit similarly patterned ground where shallow fracturing has drawn polygons on the surface.

This patterning may result from cycles of contraction and expansion.

The left image shows ground within the targeted landing area NASA's Phoenix Mars Lander before the winter frost had entirely disappeared from the surface.

The bright ice in shallow crevices accentuates the area's polygonal fracturing pattern. The polygons are a few meters (several feet) across.

The image is a small portion of an exposure taken in March 2008 by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.

The image on the right is an aerial view of similarly patterned ground in Antarctica.

The Phoenix Mission is led by the University of Arizona on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory. Spacecraft development is by Lockheed Martin Space Systems.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo.

Comparing the topographic long profiles of gullies on Earth and Mars

NASA Astrophysics Data System (ADS)

Conway, Susan; Balme, Matthew; Murray, John; Towner, Martin

2014-05-01

Liquid water is not stable under the present atmospheric conditions on the martian surface. Hence, the discovery of widespread recently active kilometre-scale gullies that resemble those carved by water on Earth [1,2], was extremely surprising. Some authors suggest that either carbon dioxide driven processes or dry mass wasting could explain these features [3-6]. However, recent work has shown that some aspects of gully-morphology, such as braiding and streamlined features, are hard to explain with these mechanisms [e.g., 7,8]. In this study we have used topographic long profiles to investigate the formation mechanism of martian gullies. On Earth it is recognised that certain forms of long-profiles can be linked to a particular process, for example, at equilibrium fluvial systems have a profile curve of exponential decay [9]. However, these shapes have not been generalised for kilometre-scale landforms, such as gullies. We used differential GPS data and airborne laser altimeter data on Earth (LiDAR) from NSA-funded NCALM and UK's NERC ARSF to generate profile-data for gullies with a fluvial and debris flow origin. On Mars we used stereo-images from the HiRISE camera (25 cm/pix) and generated the gully-profiles using the manual point-matching method of Kreslavsky [10]. We found that the shape of gully long profiles on Mars is similar to that of both fluvial and debris flow gullies on Earth. However, more of the martian gullies we have studied are similar to fluvial gullies than to debris flow gullies. The slopes of the gully long profiles on Mars tend to be shallower than fluvial gullies on Earth, but this can be accounted for by the difference in gravity between Earth and Mars. References cited: [1] M.C. Malin and K.S. Edgett, Science, (2000), 288,2330-2335.[2] M.C. Malin et al., Science, (2006), 314,1573-1577. [3] T. Shinbrot et al., Proc Natl Acad Sci U A, (2004), 101,8542-8546. [4] S. Diniega et al., Icarus, (2013), 225,526-537. [5] T. Ishii and S. Sasaki, Lunar

Stochastic late accretion to Earth, the Moon, and Mars.

PubMed

Bottke, William F; Walker, Richard J; Day, James M D; Nesvorny, David; Elkins-Tanton, Linda

2010-12-10

Core formation should have stripped the terrestrial, lunar, and martian mantles of highly siderophile elements (HSEs). Instead, each world has disparate, yet elevated HSE abundances. Late accretion may offer a solution, provided that ≥0.5% Earth masses of broadly chondritic planetesimals reach Earth's mantle and that ~10 and ~1200 times less mass goes to Mars and the Moon, respectively. We show that leftover planetesimal populations dominated by massive projectiles can explain these additions, with our inferred size distribution matching those derived from the inner asteroid belt, ancient martian impact basins, and planetary accretion models. The largest late terrestrial impactors, at 2500 to 3000 kilometers in diameter, potentially modified Earth's obliquity by ~10°, whereas those for the Moon, at ~250 to 300 kilometers, may have delivered water to its mantle.

Mineral remains of early life on Earth? On Mars?

USGS Publications Warehouse

Iberall, Robbins E.; Iberall, A.S.

1991-01-01

The oldest sedimentary rocks on Earth, the 3.8-Ga Isua Iron-Formation in southwestern Greenland, are metamorphosed past the point where organic-walled fossils would remain. Acid residues and thin sections of these rocks reveal ferric microstructures that have filamentous, hollow rod, and spherical shapes not characteristic of crystalline minerals. Instead, they resemble ferric-coated remains of bacteria. Because there are no earlier sedimentary rocks to study on Earth, it may be necessary to expand the search elsewhere in the solar system for clues to any biotic precursors or other types of early life. A study of morphologies of iron oxide minerals collected in the southern highlands during a Mars sample return mission may therefore help to fill in important gaps in the history of Earth's earliest biosphere. -from Authors

Titan's inventory of organic surface materials

USGS Publications Warehouse

Lorenz, R.D.; Mitchell, K.L.; Kirk, R.L.; Hayes, A.G.; Aharonson, O.; Zebker, H.A.; Paillou, P.; Radebaugh, J.; Lunine, J.I.; Janssen, M.A.; Wall, S.D.; Lopes, R.M.; Stiles, B.; Ostro, S.; Mitri, Giuseppe; Stofan, E.R.

2008-01-01

Cassini RADAR observations now permit an initial assessment of the inventory of two classes, presumed to be organic, of Titan surface materials: polar lake liquids and equatorial dune sands. Several hundred lakes or seas have been observed, of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas reserves on Earth. Dark dunes cover some 20% of Titan's surface, and comprise a volume of material several hundred times larger than Earth's coal reserves. Overall, however, the identified surface inventories (>3 ?? 104 km3 of liquid, and >2 ?? 105 km3 of dune sands) are small compared with estimated photochemical production on Titan over the age of the solar system. The sand volume is too large to be accounted for simply by erosion in observed river channels or ejecta from observed impact craters. The lakes are adequate in extent to buffer atmospheric methane against photolysis in the short term, but do not contain enough methane to sustain the atmosphere over geologic time. Unless frequent resupply from the interior buffers this greenhouse gas at exactly the right rate, dramatic climate change on Titan is likely in its past, present and future. Copyright 2008 by the American Geophysical Union.

Measurements of the north polar cap of Mars and the earth's Northern Hemisphere ice and snow cover

NASA Technical Reports Server (NTRS)

Foster, J.; Owe, M.; Capen, C.

1986-01-01

The boundaries of the polar caps of Mars have been measured on more than 3000 photographs since 1905 from the plate collection at the Lowell Observatory. For the earth, the polar caps have been accurately mapped only since the mid 1960s when satellites were first available to synoptically view the polar regions. The polar caps of both planets wax and wane in response to changes in the seasons, and interannual differences in polar cap behavior on Mars as well as earth are intimately linked to global energy balance. Data on the year to year variations in the extent of the north polar caps of Mars and earth have been assembled and compared, although only 6 years of concurrent data were available for comparison.

Titan Explorer: The Next Step in the Exploration of a Mysterious World

NASA Technical Reports Server (NTRS)

Levine, Joel S.; Wright, Henry S.

2005-01-01

The Titan Explorer Mission outlined in this report is a proposed next step in the exploration of Titan, following the highly successful Huygens Titan probe of 2005. The proposed Titan Explorer Mission consists of an Orbiter and an Airship that traverses the atmosphere of Titan and can land on its surface. The Titan Explorer Mission is science driven and addresses some of the fundamental questions about the atmosphere, surface and evolution of Titan, which will add to our understanding of the origin and evolution of life on Earth and assess the likelihood of life elsewhere in the Solar System.

Titan's impact history

NASA Astrophysics Data System (ADS)

Zahnle, Kevin

2010-04-01

Impacts play a major role in the growth and evolution of planets, satellites, and other nameless things. Titan is no exception. This talk will address a subset of the following topics: (i) The modern impact rate is constrained by the population of Centaurs and the impact rate at Jupiter. (ii) Titan's thick atmosphere and volatile surface cause it to respond to major impacts in an Earth-like manner. The impact that made Menrva - the 440 km diameter impact basin sited near the current apex of Titan's motion - was big enough to raise the average global surface temperature above 273 K, which suggests that water rain was possible. This would have been followed by methane drizzles lasting for thousands of years. More modest impacts will generate crater lakes and will saturate the atmosphere with methane, the latter leading to hundreds of years of intermittent drizzle. (iii) Impact ejecta from Menrva will strike Hyperion and should saturate the latter with sesquinary craters. (iv) In any modern story of how Titan got its atmosphere, solar nebular condensates (comets) deliver the volatiles. A consequence of a cometogenic atmosphere is that the atmosphere is heavily processed by strong shocks. The high temperatures produce a wide range of chemical species that would not otherwise be abundant. Some of these will survive to mix into the atmosphere (e.g., CO) or freeze out to fall to the surface (e.g. CO2). (v) That Titan even has an atmosphere, when Callisto and Ganymede do not, is an excellent question. The leading explanation is that Titan alone was made from ammonia - and methane - rich stuff. But the competition between impact delivery and impact expulsion of volatiles can strongly favor Titan over Callisto. Stable isotopes as well as total volatile inventories provide constraints.

Barchan asymmetry as a proxy for wind conditions on Earth and Mars

NASA Astrophysics Data System (ADS)

Dwyer, Diarmuid; Bourke, Mary

2014-05-01

The absence of weather stations in many remote arid regions on Earth and Mars introduces a difficulty in testing atmospheric circulation models. While several proxies have been recommended for the reconstruction of wind regimes, they remain to be tested in a wide range of terrains. We examine the relationship between instrumented wind data and barchan asymmetric shape in order to ascertain if this dune attribute can be used to reliably infer aspects of a wind regime. The two study areas are located in La Joya, Peru and the Namib Desert, Namibia. Dune observations were made using high resolution satellite images available on Google Earth. The wind data was sourced from Wunderground and the National Peruvian Meteorological Service. Asymmetric barchans are reported to form in bimodal wind regimes (Tsoar, 1984). The barchan dune is oriented parallel to the strong wind regime and is modified by oblique gentler winds. Our analysis of wind data and dune form supports the Tsoar model for barchan asymmetry. Numerical simulations have shown that the duration of winds in bi-directional regimes also influences asymmetry (Parteli, 2014). Our analysis finds good agreement between the model simulations of Parteli et al (2014) and the instrument data for Namibia and Peru. We use our findings on Earth to infer formative wind direction and duration at five sites on Mars. These are the first maps of wind direction and relative duration for Mars. Our findings do not concur with previous estimates of wind direction derived either from the NASA Ames General Circulation Model or dune slipface orientation. We propose that the Parteli et al (2014) approach can be usefully applied to remote areas on Earth and Mars to extract data on relative wind duration and direction. Parteli, E.J.R., Duran, O., Bourke, M.C., Tsoar, H., Poschel, T., Herrmann, H.J., (in press). Origins of barchan dune asymmetry: Insights from numerical simulations. Aeolian Research. Tsoar, H., (1984). The formation of seif

Controlling Factors of the Fate of Ionospheric Outflow at Earth and Mars

NASA Astrophysics Data System (ADS)

Liemohn, M. W.; Welling, D. T.; Ilie, R.; Ganushkina, N. Y.; Johnson, B. C.; Xu, S.; Dong, C.

2015-12-01

Both Earth and Mars experience ionospheric outflow, but the radically different magnetic field configurations at the two planets yield significantly different patterns of outflow and processes governing outflow. This study examines a set of numerical simulations for Earth and Mars to explore the factors controlling ionospheric outflow and the fate of the escaping ions (immediate precipitation, magnetospheric recirculation, or loss to deep space). Specifically, simulation results from the Space Weather Modeling Framework (SWMF), which is capable of handling both planetary space environments, are analyzed to assess the physical processes governing the fate of ionospheric ions. Velocity streamlines from the SWMF results are traced from the high-latitude inner boundary of the BATS-R-US MHD simulation domain and followed through geospace. Some of these streamlines return to the inner boundary of the simulation domain, others extend to the outer boundary of the domain, while most others eventually cross (or at least approach) the magnetospheric equatorial plane. At Earth, this plane is well defined, while at Mars there are multiple mini-magnetospheres in which ionospheric ions can become trapped. These streamlines are categorized according to their eventual destination. Multi-fluid MHD simulations are examined in this study, assessing the influence of species mass on trajectories through near-planet space. Steady-state numerical experiments with different levels of solar driving are examined to quantify the influence of each driver on outflow characteristics and the fate of outflowing ions. Real event intervals are considered to assess flows in a time-varying magnetospheric system. For Earth, as solar wind dynamic pressure increases, the dominant outflow region moves to lower latitudes and significantly more of the outflowing ions escape to deep space. As the interplanetary magnetic field increases in southward magnitude, the region of dominant outflow shifts to lower

Lightning generation in Titan due to the electrical self-polarization properties of Methane

NASA Astrophysics Data System (ADS)

Quintero, A.; Falcón, N.

2009-05-01

We describe an electrical charge process in Titan's thunderclouds, due to the self-polarization properties or pyroelectricity of methane, which increases the internal electric field in thunderclouds and facilitates the charge generation and separation processes. Microphysics that generates lightning flashes is associated with the physical and chemical properties of the local atmosphere, so methane could be the principal agent of the electrical activity because of its great concentration in Titan's atmosphere. Besides, Titan's electrical activity should not be very influenced by Saturn's magnetosphere because lightning occurs at very low altitude above Titan's surface, compared with the greater distance of Saturn's magnetosphere and Titan's troposphere. Using an electrostatic treatment, we calculate the internal electric field of Titan's thunderclouds due to methane's pyroelectrical properties, 7.05×10^11 Vm^-1; and using the telluric capacitor approximation for thunderclouds, we calculate the total charge obtained for a typical Titan thundercloud, 2.67×10^9 C. However, it is not right to use an electrostatic treatment because charge times are very fast due to the large methane concentration in Titan's clouds and the life time of thunderclouds is very low (around 2 hours). We consider a time dependent mechanism, employing common Earth atmospheric approaches, because of the similitude in chemical composition of both atmospheres (mainly nitrogen), so the typical charge of a thundercloud in Titan should reach between 20 C to 40 C, like on Earth. We obtain that lightning occurs with a frequency between 2 and 6 KHz. In Titan's atmosphere, methane concentration is higher than on Earth, and atmospheric electrical activity is stronger, so this model could be consistent with the observed phenomenology.

Venus-Earth-Mars: comparative climatology and the search for life in the solar system.

PubMed

Launius, Roger D

2012-09-19

Both Venus and Mars have captured the human imagination during the twentieth century as possible abodes of life. Venus had long enchanted humans-all the more so after astronomers realized it was shrouded in a mysterious cloak of clouds permanently hiding the surface from view. It was also the closest planet to Earth, with nearly the same size and surface gravity. These attributes brought myriad speculations about the nature of Venus, its climate, and the possibility of life existing there in some form. Mars also harbored interest as a place where life had or might still exist. Seasonal changes on Mars were interpreted as due to the possible spread and retreat of ice caps and lichen-like vegetation. A core element of this belief rested with the climatology of these two planets, as observed by astronomers, but these ideas were significantly altered, if not dashed during the space age. Missions to Venus and Mars revealed strikingly different worlds. The high temperatures and pressures found on Venus supported a "runaway greenhouse theory," and Mars harbored an apparently lifeless landscape similar to the surface of the Moon. While hopes for Venus as an abode of life ended, the search for evidence of past life on Mars, possibly microbial, remains a central theme in space exploration. This survey explores the evolution of thinking about the climates of Venus and Mars as life-support systems, in comparison to Earth.

Venus-Earth-Mars: Comparative Climatology and the Search for Life in the Solar System

PubMed Central

Launius, Roger D.

2012-01-01

Both Venus and Mars have captured the human imagination during the twentieth century as possible abodes of life. Venus had long enchanted humans—all the more so after astronomers realized it was shrouded in a mysterious cloak of clouds permanently hiding the surface from view. It was also the closest planet to Earth, with nearly the same size and surface gravity. These attributes brought myriad speculations about the nature of Venus, its climate, and the possibility of life existing there in some form. Mars also harbored interest as a place where life had or might still exist. Seasonal changes on Mars were interpreted as due to the possible spread and retreat of ice caps and lichen-like vegetation. A core element of this belief rested with the climatology of these two planets, as observed by astronomers, but these ideas were significantly altered, if not dashed during the space age. Missions to Venus and Mars revealed strikingly different worlds. The high temperatures and pressures found on Venus supported a “runaway greenhouse theory,” and Mars harbored an apparently lifeless landscape similar to the surface of the Moon. While hopes for Venus as an abode of life ended, the search for evidence of past life on Mars, possibly microbial, remains a central theme in space exploration. This survey explores the evolution of thinking about the climates of Venus and Mars as life-support systems, in comparison to Earth. PMID:25371106

Venus-Earth-Mars: Comparative Climatology and the Search for Life in the Solar System

NASA Astrophysics Data System (ADS)

Launius, Roger D.

2012-09-01

Both Venus and Mars have captured the human imagination during the twentieth century as possible abodes of life. Venus had long enchanted humans - all the more so after astronomers realized it was shrouded in a mysterious cloak of clouds permanently hiding the surface from view. It was also the closest planet to Earth, with nearly the same size and surface gravity. These attributes brought myriad speculations about the nature of Venus, its climate, and the possibility of life existing there in some form. Mars also harbored interest as a place where life had or might still exist. Seasonal changes on Mars were interpreted as due to the possible spread and retreat of ice caps and lichen-like vegetation. A core element of this belief rested with the climatology of these two planets, as observed by astronomers, but these ideas were significantly altered, if not dashed during the space age. Missions to Venus and Mars revealed strikingly different worlds. The high temperatures and pressures found on Venus supported a "runaway greenhouse theory," and Mars harbored an apparently lifeless landscape similar to the surface of the Moon. While hopes for Venus as an abode of life ended, the search for evidence of past life on Mars, possibly microbial, remains a central theme in space exploration. This survey explores the evolution of thinking about the climates of Venus and Mars as life-support systems, in comparison to Earth.

Origin and evolution of the atmospheres of early Venus, Earth and Mars

NASA Astrophysics Data System (ADS)

Lammer, Helmut; Zerkle, Aubrey L.; Gebauer, Stefanie; Tosi, Nicola; Noack, Lena; Scherf, Manuel; Pilat-Lohinger, Elke; Güdel, Manuel; Grenfell, John Lee; Godolt, Mareike; Nikolaou, Athanasia

2018-05-01

We review the origin and evolution of the atmospheres of Earth, Venus and Mars from the time when their accreting bodies were released from the protoplanetary disk a few million years after the origin of the Sun. If the accreting planetary cores reached masses ≥ 0.5 M_Earth before the gas in the disk disappeared, primordial atmospheres consisting mainly of H_2 form around the young planetary body, contrary to late-stage planet formation, where terrestrial planets accrete material after the nebula phase of the disk. The differences between these two scenarios are explored by investigating non-radiogenic atmospheric noble gas isotope anomalies observed on the three terrestrial planets. The role of the young Sun's more efficient EUV radiation and of the plasma environment into the escape of early atmospheres is also addressed. We discuss the catastrophic outgassing of volatiles and the formation and cooling of steam atmospheres after the solidification of magma oceans and we describe the geochemical evidence for additional delivery of volatile-rich chondritic materials during the main stages of terrestrial planet formation. The evolution scenario of early Earth is then compared with the atmospheric evolution of planets where no active plate tectonics emerged like on Venus and Mars. We look at the diversity between early Earth, Venus and Mars, which is found to be related to their differing geochemical, geodynamical and geophysical conditions, including plate tectonics, crust and mantle oxidation processes and their involvement in degassing processes of secondary N_2 atmospheres. The buildup of atmospheric N_2, O_2, and the role of greenhouse gases such as CO_2 and CH_4 to counter the Faint Young Sun Paradox (FYSP), when the earliest life forms on Earth originated until the Great Oxidation Event ≈ 2.3 Gyr ago, are addressed. This review concludes with a discussion on the implications of understanding Earth's geophysical and related atmospheric evolution in relation

Prebiotic-like chemistry on Titan.

PubMed

Raulin, François; Brassé, Coralie; Poch, Olivier; Coll, Patrice

2012-08-21

Titan, the largest satellite of Saturn, is the only one in the solar system with a dense atmosphere. Mainly composed of dinitrogen with several % of methane, this atmosphere experiences complex organic processes, both in the gas and aerosol phases, which are of prebiotic interest and within an environment of astrobiological interest. This tutorial review presents the different approaches which can be followed to study such an exotic place and its chemistry: observation, theoretical modeling and experimental simulation. It describes the Cassini-Huygens mission, as an example of observational tools, and gives the new astrobiologically oriented vision of Titan which is now available by coupling the three approaches. This includes the many analogies between Titan and the Earth, in spite of the much lower temperature in the Saturn system, the complex organic chemistry in the atmosphere, from the gas to the aerosol phases, but also the potential organic chemistry on Titan's surface, and in its possible internal water ocean.

The Veils of Titan

NASA Image and Video Library

2004-05-06

The veils of Saturn's most mysterious moon have begun to lift in Cassini's eagerly awaited first glimpse of the surface of Titan, a world where scientists believe organic matter rains from hazy skies and seas of liquid hydrocarbons dot a frigid surface. Surface features previously observed only from Earth-based telescopes are now visible in images of Titan taken in mid-April by Cassini through one of the narrow angle camera's spectral filters specifically designed to penetrate the thick atmosphere. The image scale is 230 kilometers (143 miles) per pixel, and it rivals the best Earth-based images. The two images displayed here show Titan from a vantage point 17 degrees below its equator, yielding a view from 50 degrees north latitude all the way to its south pole. The image on the left was taken four days after the image on the right. Titan rotated 90 degrees in that time. The two images combined cover a region extending halfway around the moon. The observed brightness variations suggest a diverse surface, with variations in average reflectivity on scales of a couple hundred kilometers. The images were taken through a narrow filter centered at 938 nanometers, a spectral region in which the only obstacle to light is the carbon-based, organic haze. Despite the rather long 38-second exposure times, there is no noticeable smear due to spacecraft motion. The images have been magnified 10 times and enhanced in contrast to bring out details. No further processing to remove the effects of the overlying atmosphere has been performed. The superimposed grid over the images illustrates the orientation of Titan -- north is up and rotated 25 degrees to the left -- as well as the geographical regions of the satellite that are illuminated and visible. The yellow curve marks the position of the boundary between day and night on Titan. The enhanced image contrast makes the region within 20 degrees of this day and night division darker than usual. The Sun illuminates Titan from the

Touchdown on Titan

NASA Technical Reports Server (NTRS)

Morring, Frank, Jr.

2004-01-01

Europe's Huygens probe is on target for a Dec. 25 separation from the Cassini Saturn orbiter that has carried it like a baby for more than seven years. The probe will spend three weeks coasting to a plunge into Titan's thick atmosphere on the morning of Jan. 14. If all goes as planned, the 349-kg. Huygens will spend more than 2 hr. descending by parachute to the mysterious surface of the planet-sized moon, and hopefully devote yet more time to broadcasting data after it lands. Before the day is over, Huygens is programmed to beam about 30 megabytes of data - including some 1,100 images-back to Earth through Cassini, a trip that will take some 75 min. to complete over the 1- billion-km. distance that separates the two planets. Within that data should be answers to questions that date back to 1655, when Dutch astronomer Christiaan Huygens found the moon with a homemade telescope and named it for the family of giants the ancient Greeks believed once ruled the earth. In the Solar System, there is no other world like Titan, with a nitrogen and methane atmospheric and a cold, hidden surface darker than Earth under the full Moon.

Pioneering Mars: Turning the Red Planet Green with Earth's Smallest Settlers

ERIC Educational Resources Information Center

Cwikla, Julie; Milroy, Scott; Reider, David; Skelton, Tara

2014-01-01

Pioneering Mars: Turning the Red Planet Green with the Earth's Smallest Settlers (http://pioneeringmars.org) provides a partnership model for STEM (science, technology, engineering, and mathematics) learning that brings university scientists together with high school students to investigate whether cyanobacteria from Antarctica could survive on…

An Overview of Mars Vicinity Transportation Concepts for a Human Mars Mission

NASA Technical Reports Server (NTRS)

Dexter, Carol E.; Kos, Larry

1998-01-01

To send a piloted mission to Mars, transportation systems must be developed for the Earth to Orbit, trans Mars injection (TMI), capture into Mars orbit, Mars descent, surface stay, Mars ascent, trans Earth injection (TEI), and Earth return phases. This paper presents a brief overview of the transportation systems for the Human Mars Mission (HMM) only in the vicinity of Mars. This includes: capture into Mars orbit, Mars descent, surface stay, and Mars ascent. Development of feasible mission scenarios now is important for identification of critical technology areas that must be developed to support future human missions. Although there is no funded human Mars mission today, architecture studies are focusing on missions traveling to Mars between 2011 and the early 2020's.

Project Cassini: a Saturn Orbiter/titan Probe Mission Proposal

NASA Astrophysics Data System (ADS)

Gautier, D.; Ip, W. H.

1984-12-01

Titan is the only moon in the solar system with a substantial atmosphere. The organic chemistry of its N2-CH4 atmosphere may resemble that of the earth's primitive atmosphere before life arose. The investigation of the synthesis of prebiotic molecules in Titan's atmosphere and the atmospheric and surface environments of this planet-sized moon will be the focal point of the Cassini Project proposed to the European Space Agency for an international Saturn Orbiter/Titan Probe mission.

Selections from 2017: Discoveries in Titan's Atmosphere

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-12-01

Editors note:In these last two weeks of 2017, well be looking at a few selections that we havent yet discussed on AAS Nova from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume in January.Carbon Chain Anions and the Growth of Complex Organic Molecules in Titans IonospherePublished July2017Main takeaway:Graphic depicting some of the chemical reactions taking place in Titans atmosphere, leading to the generation of organic haze particles. [ESA]In a recently published study led by Ravi Desai (University College London), scientists used data from the Cassini mission to identify negatively charged molecules known as carbon chain anions in the atmosphere of Saturns largest moon, Titan.Why its interesting:Carbon chain anions are the building blocks ofmore complex molecules, and Titans thick nitrogen and methane atmosphere mightmimic the atmosphere of earlyEarth. This first unambiguous detection of carbon chain anions in a planet-like atmosphere might therefore teach us about the conditions and chemical reactions that eventually led to the development of life on Earth. And ifwe can use Titan to learn about how complex molecules grow from these anion chains, we may be able to identify auniversal pathway towards the ingredients for life.What weve learned so far:Cassini measured fewer and fewer lower-mass anions the deeper in Titans ionosphere that it looked and at the same time,an increase in the number of precursors to larger aerosol molecules further down. This tradeoff strongly suggests that the anions are indeed involved in building up the more complex molecules, seeding their eventual growth into the complex organic haze of Titans lower atmosphere.CitationR. T. Desai et al 2017 ApJL 844 L18. doi:10.3847/2041-8213/aa7851

Weather on Titan

NASA Astrophysics Data System (ADS)

Griffith, C. A.; Hall, J. L.; Geballe, T. R.

2000-10-01

Titan's atmosphere potentially sports a cycle similar to the hydrologic one on Earth with clouds, rain and seas, but with methane playing the terrestrial role of water. Over the past ten years many independent efforts indicated no strong evidence for cloudiness until some unique spectra were analyzed in 1998 (Griffith et al.). These surprising observations displayed enhanced fluxes of 14-200% on two nights at precisely the wavelengths (windows) that sense Titan's lower altitude where clouds might reside. The morphology of these enhancements in all 4 windows observed indicate that clouds covered ~6-9% of Titan's surface and existed at ~15 km altitude. Here I discuss new observations recorded in 1999 aimed to further characterize Titan's clouds. While we find no evidence for a massive cloud system similar to the one observed previously, 1%-4% fluctuations in flux occur daily. These modulations, similar in wavelength and morphology to the more pronounced ones observed earlier, suggest the presence of clouds covering <=1% of Titan's disk. The variations are too small to have been detected by most prior measurements. Repeated observations, spaced 30 minutes apart, indicate a temporal variability observable in the time scale of a couple of hours. The cloud heights hint that convection governs their evolutions. Their short lives point to the presence of rain. C. A. Griffith and J. L. Hall are supported by the NASA Planetary Astronomy Program NAG5-6790.

Habitability Assessment on Earth in Preparation for Mars Science Laboratory

NASA Astrophysics Data System (ADS)

Conrad, Pamela; Mahaffy, Paul

NASA's upcoming Mars Science Laboratory mission is designed to explore and quantitatively assess a local region on the surface of Mars as a potential habitat for life, past or present. In advance of this complex mission, we are developing metrics from which to frame such an assess-ment. Evaluation of habitability potential is clearly different and more challenging than direct measurement of a discrete potential such as a voltage, which is a single parameter expressing the magnitude of a difference between a ground state and a measurable charge. Habitability potential is likely to require measurement of several parameters whose relationships determine the threshold value above which an environment may be deemed habitable in some regard. On Earth, in the continuum from uninhabitable to inhabited, one can measure environmental parameters that co-vary with biological parameters such as total biomass, functional diversity and/or ecotype along that binary join. Recognition of this statistical association facilitates development of predictive tools for assessment of habitability potential in environments that fall in between the end members of the habitability spectrum. The success of a habitabil-ity investigation on Mars depends upon development of criteria that can be agreed upon by the scientific community that will enable interpretation of the data from experiments on Mars within the context of a scalar notion of habitability, which we describe in this report. The scalar approach involves (1) measurement of physical, chemical and biological features of the candidate environment, (2) normalization of the scales over which they vary and (3) evaluation of their covariance. Inclusion of biological measurements, e.g., total biomass, diversity, ecotype, etc., serves as a benchmark in Earth environments, and the subsequent step in a campaign to develop a habitability scale involves measuring and analyzing only the chemical and physical environmental parameters, then

The Titan Sky Simulator ™ - Testing Prototype Balloons in Conditions Approximating those in Titan's Atmosphere

NASA Astrophysics Data System (ADS)

Nott, Julian

This paper will describe practical work flying prototype balloons in the "The Titan Sky Simulator TM " in conditions approximating those found in Titan's atmosphere. Saturn's moon, Titan, is attracting intense scientific interest. This has led to wide interest in exploring it with Aerobots, balloons or airships. Their function would be similar to the Rovers exploring Mars, but instead of moving laboriously across the rough terrain on wheels, they would float freely from location to location. To design any balloon or airship it is essential to know the temperature of the lifting gas as this influences the volume of the gas, which in turn influences the lift. To determine this temperature it is necessary to know how heat is transferred between the craft and its surroundings. Heat transfer for existing balloons is well understood. However, Titan conditions are utterly different from those in which balloons have ever been flown, so heat transfer rates cannot currently be calculated. In particular, thermal radiation accounts for most heat transfer for existing balloons but over Titan heat transfer will be dominated by convection. To be able to make these fundamental calculations, it is necessary to get fundamental experimental data. This is being obtained by flying balloons in a Simulator filled with nitrogen gas at very low temperature, about 95° K / minus 180° C, typical of Titan's temperatures. Because the gas in the Simulator is so cold, operating at atmospheric pressure the density is close to that of Titan's atmosphere. "The Titan Sky Simulator TM " has an open interior approximately 4.5 meter tall and 2.5 meters square. It has already been operated at 95° K/-180° C. By the time of the Conference it is fully expected to have data to present from actual balloons flying at this temperature. Perhaps the most important purpose of this testing is to validate numerical [computational fluid dynamics] models being developed by Tim Colonius of Caltech. These numerical

Venus, Earth, Mars: Comparative ion escape caused by the interaction with the solar wind

NASA Astrophysics Data System (ADS)

Barabash, Stas

For the solar system planets the non-thermal atmospheric escape exceeds by far the Jean escape for particles heavier than helium. In this talk we consider only ion escape and compare the total ion escape rates for Venus, Earth, and Mars caused by the interaction with the solar wind. We review the most recent data on the escape rates based on measurements from Mars Express, Venus Express, and Cluster. The comparison of the available numbers show that despite large differences in the atmospheric masses between these three planets (a factor of 100 -200), different types of the interactions with the solar wind (magnetized and non-magnetized obstacles), the escape rates for Mars, Venus, and the Earth are within the range 1024 - 1025 s-1 . Surprisingly, the expected shielding of the Earth atmosphere by the intrinsic magnetic field is not as efficient as one may think. The reason for this is the non-thermal escape caused by the solar wind interaction is a energy -limited process. Indeed, normalizing the escape rates to the planet-dependent escape energy and power available in the solar wind results in the normalized escape rates deferring only on a factor between three planets. The larger Earth's magnetosphere intercepts and tunnels down to the ionosphere more energy from the solar wind than more compact interaction regions of non-magnetized planets.

Accurate spin axes and solar system dynamics: Climatic variations for the Earth and Mars

NASA Astrophysics Data System (ADS)

Edvardsson, S.; Karlsson, K. G.; Engholm, M.

2002-03-01

Celestial mechanical simulations from a purely classical point of view of the solar system, including our Moon and the Mars moons - Phobos and Deimos - are carried out for 2 millions of years before present. Within the classical approximation, the results are derived at a very high level of accuracy. Effects from general relativity for a number of variables are investigated and found to be small. For climatic studies of about 1 Myr, general relativity can safely be ignored. Three different and independent integration schemes are used in order to exclude numerical anomalies. The converged results from all methods are found to be in complete agreement. For verification, a number of properties such as spin axis precession, nutation, and orbit inclination for Earth and Mars have been calculated. Times and positions of equinoxes and solstices are continously monitored. As also observed earlier, the obliquity of the Earth is stabilized by the Moon. On the other hand, the obliquity of Mars shows dramatic variations. Climatic influences due to celestial variables for the Earth and Mars are studied. Instead of using mean insolation as in the usual applications of Milankovitch theory, the present approach focuses on the instantaneous solar radiation power (insolation) at each summer solstice. Solar radiation power is compared to the derivative of the icevolume and these quantities are found to be in excellent agreement. Orbital precessions for the inner planets are studied as well. In the case of Mercury, it is investigated in detail.

Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins

USGS Publications Warehouse

Cartwright, Richard; Clayton, Jordan A.; Kirk, Randolph L.

2011-01-01

Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (Rb) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have Rb values greater than the expected range (3.0–5.0) for dendritic networks; comparisons with Rb values determined for Titanbasins, in conjunction with similarities in network patterns, suggest that portions of Titan's north polar region are modified by tectonic forces. Sufficient elevation data existed to calculate bed slope and potential fluvial sedimenttransport rates in at least one Titanbasin, indicating that 75 mm water ice grains (observed at the Huygens landing site) should be readily entrained given sufficient flow depths of liquid hydrocarbons. Volumetric sedimenttransport estimates suggest that ~6700–10,000 Titan years (~2.0–3.0 x 105 Earth years) are required to erode this basin to its minimum relief (assuming constant 1 m and 1.5 m flows); these lowering rates increase to ~27,000–41,000 Titan years (~8.0–12.0 x 105 Earth years) when flows in the north polar region are restricted to summer months.

3D Simulations of methane convective storms on Titan's atmosphere

NASA Astrophysics Data System (ADS)

Hueso, R.; Sánchez-Lavega, A.

2005-08-01

The arrival of the Cassini/Huygens mission to Titan has opened an unprecedented opportunity to study the atmosphere of this satellite. Under the pressure-temperature conditions on Titan, methane, a large atmospheric component amounting perhaps to a 3-5% of the atmosphere, is close to its triple point, potentially playing a similar role as water on Earth. The Huygens probe has shown a terrain shaped by erosion of probably liquid origin, suggestive of past rain. On the other hand, Voyager IRIS spectroscopic observations of Titan imply a saturated atmosphere of methane (amounting perhaps to 150 covered by methane clouds, if we think on Earth meteorology. However, observations from Earth and Cassini have shown that clouds are localized, transient and fast evolving, in particular in the South Pole (currently in its summer season). This might imply a lack of widespread presence on Titan of nuclei where methane could initiate condensation and particle growth with subsequent precipitation. We investigate different scenarios of moist convective storms on Titan using a complete 3D atmospheric model that incorporates a full microphysics treatment required to study cloud formation processes under a saturated atmosphere with low concentration of condensation nuclei. We study local convective development under a variety of atmospheric conditions: sub-saturation, super-saturation, abundances of condensation nuclei fall, condensation nuclei lifted from the ground or gently falling from the stratosphere. We show that under the appropriate circumstances, precipitation rates comparable to typical tropical storms on Earth can be found. 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.

Autonomous flight control for a Titan exploration aerobot

NASA Technical Reports Server (NTRS)

Elfes, Alberto; Montgomery, James F.; Hall, Jeffrey L.; Joshi, Sanjay S.; Payne, Jeffrey; Bergh, Charles F.

2005-01-01

Robotic lighter-than-air vehicles, or aerobots, provide strategic platform for the exploration of planets and moons with an atmosphere, such as Venus, Mars, Titan and the gas giants. In this paper, we discuss steps towards the development of an autonomy architecture, and concentrate on the autonomous fight control subsystem.

The greenhouse and antigreenhouse effects on Titan

NASA Technical Reports Server (NTRS)

Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

1991-01-01

The parallels between the atmospheric thermal structure of the Saturnian satellite Titan and the hypothesized terrestrial greenhouse effect can serve as bases for the evaluation of competing greenhouse theories. Attention is presently drawn to the similarity between the roles of H2 and CH4 on Titan and CO2 and H2O on earth. Titan also has an antigreenhouse effect due to a high-altitude haze layer which absorbs at solar wavelengths, while remaining transparent in the thermal IR; if this haze layer were removed, the antigreenhouse effect would be greatly reduced, exacerbating the greenhouse effect and raising surface temperature by over 20 K.

Polar vortices on Earth and Mars: A comparative study of the climatology and variability from reanalyses.

PubMed

Mitchell, D M; Montabone, L; Thomson, S; Read, P L

2015-01-01

Polar vortices on Mars provide case-studies to aid understanding of geophysical vortex dynamics and may help to resolve long-standing issues regarding polar vortices on Earth. Due to the recent development of the first publicly available Martian reanalysis dataset (MACDA), for the first time we are able to characterise thoroughly the structure and evolution of the Martian polar vortices, and hence perform a systematic comparison with the polar vortices on Earth. The winter atmospheric circulations of the two planets are compared, with a specific focus on the structure and evolution of the polar vortices. The Martian residual meridional overturning circulation is found to be very similar to the stratospheric residual circulation on Earth during winter. While on Earth this residual circulation is very different from the Eulerian circulation, on Mars it is found to be very similar. Unlike on Earth, it is found that the Martian polar vortices are annular, and that the Northern Hemisphere vortex is far stronger than its southern counterpart. While winter hemisphere differences in vortex strength are also reported on Earth, the contrast is not as large. Distinctions between the two planets are also apparent in terms of the climatological vertical structure of the vortices, in that the Martian polar vortices are observed to decrease in size at higher altitudes, whereas on Earth the opposite is observed. Finally, it is found that the Martian vortices are less variable through the winter than on Earth, especially in terms of the vortex geometry. During one particular major regional dust storm on Mars (Martian year 26), an equatorward displacement of the vortex is observed, sharing some qualitative characteristics of sudden stratospheric warmings on Earth.

Polar vortices on Earth and Mars: A comparative study of the climatology and variability from reanalyses

PubMed Central

Mitchell, D M; Montabone, L; Thomson, S; Read, P L

2015-01-01

Polar vortices on Mars provide case-studies to aid understanding of geophysical vortex dynamics and may help to resolve long-standing issues regarding polar vortices on Earth. Due to the recent development of the first publicly available Martian reanalysis dataset (MACDA), for the first time we are able to characterise thoroughly the structure and evolution of the Martian polar vortices, and hence perform a systematic comparison with the polar vortices on Earth. The winter atmospheric circulations of the two planets are compared, with a specific focus on the structure and evolution of the polar vortices. The Martian residual meridional overturning circulation is found to be very similar to the stratospheric residual circulation on Earth during winter. While on Earth this residual circulation is very different from the Eulerian circulation, on Mars it is found to be very similar. Unlike on Earth, it is found that the Martian polar vortices are annular, and that the Northern Hemisphere vortex is far stronger than its southern counterpart. While winter hemisphere differences in vortex strength are also reported on Earth, the contrast is not as large. Distinctions between the two planets are also apparent in terms of the climatological vertical structure of the vortices, in that the Martian polar vortices are observed to decrease in size at higher altitudes, whereas on Earth the opposite is observed. Finally, it is found that the Martian vortices are less variable through the winter than on Earth, especially in terms of the vortex geometry. During one particular major regional dust storm on Mars (Martian year 26), an equatorward displacement of the vortex is observed, sharing some qualitative characteristics of sudden stratospheric warmings on Earth. PMID:26300564

Surface-Atmosphere Connections on Titan: A New Window into Terrestrial Hydroclimate

NASA Astrophysics Data System (ADS)

Faulk, Sean

This dissertation investigates the coupling between the large-scale atmospheric circulation and surface processes on Titan, with a particular focus on methane precipitation and its influence on surface geomorphology and hydrology. As the only body in the Solar System with an active hydrologic cycle other than Earth, Titan presents a valuable laboratory for studying principles of hydroclimate on terrestrial planets. Idealized general circulation models (GCMs) are used here to test hypotheses regarding Titan's surface-atmosphere connections. First, an Earth-like GCM simulated over a range of rotation rates is used to evaluate the effect of rotation rate on seasonal monsoon behavior. Slower rotation rates result in poleward migration of summer rain, indicating a large-scale atmospheric control on Titan's observed dichotomy of dry low latitudes and moist high latitudes. Second, a Titan GCM benchmarked against observations is used to analyze the magnitudes and frequencies of extreme methane rainstorms as simulated by the model. Regional patterns in these extreme events correlate well with observed geomorphic features, with the most extreme rainstorms occurring in mid-latitude regions associated with high alluvial fan concentrations. Finally, a planetary surface hydrology scheme is developed and incorporated into a Titan GCM to evaluate the roles of surface flow, subsurface flow, infiltration, and groundmethane evaporation in Titan's climate. The model reproduces Titan's observed surface liquid and cloud distributions, and reaches an equilibrium state with limited interhemispheric transport where atmospheric transport is approximately balanced by subsurface transport. The equilibrium state suggests that Titan's current hemispheric surface liquid asymmetry, favoring methane accumulation in the north, is stable in the modern climate.

Farewell to the Earth and the Moon -ESA's Mars Express successfully tests its instruments

NASA Astrophysics Data System (ADS)

2003-07-01

The routine check-outs of Mars Express's instruments and of the Beagle-2 lander, performed during the last weeks, have been very successful. "As in all space missions little problems have arisen, but they have been carefully evaluated and solved. Mars Express continues on its way to Mars performing beautifully", comments Chicarro. The views of the Earth/Moon system were taken on 3 July 2003 by Mars Express's High Resolution Stereo Camera (HRSC), when the spacecraft was 8 million kilometres from Earth. The image taken shows true colours; the Pacific Ocean appears in blue, and the clouds near the Equator and in mid to northern latitudes in white to light grey. The image was processed by the Instrument Team at the Institute of Planetary Research of DLR, Berlin (Germany). It was built by combining a super resolution black and white HRSC snap-shot image of the Earth and the Moon with colour information obtained by the blue, green, and red sensors of the instrument. “The pictures and the information provided by the data prove the camera is working very well. They provide a good indication of what to expect once the spacecraft is in its orbit around Mars, at altitudes of only 250-300 kilometres: very high resolution images with brilliant true colour and in 3D,” says the Principal Investigator of the HRSC, Gerhard Neukum, of the Freie Universität of Berlin (Germany). This camera will be able to distinguish details of up to 2 metres on the Martian surface. Another striking demonstration of Mars Express's instruments high performance are the data taken by the OMEGA spectrometer. Once at Mars, this instrument will provide the best map of the molecular and mineralogical composition of the whole planet, with 5% of the planetary surface in high resolution. Minerals and other compounds such as water will be charted as never before. As the Red Planet is still too far away, the OMEGA team devised an ingenious test for their instrument: to detect the Earth’s surface

On the Nature of Earth-Mars Porkchop Plots

NASA Technical Reports Server (NTRS)

Woolley, Ryan C.; Whetsel, Charles W.

2013-01-01

Porkchop plots are a quick and convenient tool to help mission designers plan ballistic trajectories between two bodies. Parameter contours give rise to the familiar 'porkchop' shape. Each synodic period the pattern repeats, but not exactly, primarily due to differences in inclination and non-zero eccentricity. In this paper we examine the morphological features of Earth-to-Mars porkchop plots and the orbital characteristics that create them. These results are compared to idealistic and optimized transfers. Conclusions are drawn about 'good' opportunities versus 'bad' opportunities for different mission applications.

Resource Exploration Approaches on Mars Using Multidisciplinary Earth-based Techniques

NASA Astrophysics Data System (ADS)

Wyrick, D. Y.; Ferrill, D. A.; Morris, A. P.; Smart, K. J.

2005-12-01

Water is the most important Martian exploration target - key to finding evidence of past life and providing a crucial resource for future exploration. Water is thought to be present in vapor, liquid, and ice phases on Mars. Except for ice in polar regions, little direct evidence of current surface accumulation of water has been found. Existing research has addressed potential source areas, including meteoric water, glacial ice, and volcanic centers and areas of discharge such as large paleo-outflow channels. Missing from these analyses is characterization of migration pathways of water in the subsurface from sources to discharge areas, and the present distribution of water. It has been estimated that ~90% of the global inventory of water on Mars resides in the subsurface. Targeting potential subsurface accumulations has relied primarily on theoretical modeling and geomorphic analysis. While global scale thermal modeling and analysis of the stability of ground ice provide important constraints on potential locations of large deposits of ice or liquid water, these studies have not accounted for variations in stratigraphy and structure that may strongly influence local distribution. Depth to water or ice on Mars is thought to be controlled primarily by latitude and elevation. However, the distribution of outflow channels clearly indicates that structural, stratigraphic, and geomorphic features all play important roles in determining past and present distribution of water and ice on Mars as they do on Earth. Resource exploration and extraction is a multi-billion dollar industry on Earth that has developed into a highly sophisticated enterprise with constantly improving exploration technologies. Common to all successful exploration programs, whether for hydrocarbons or water, is detailed analysis and integration of all available geologic, geophysical and remotely sensed data. The primary issues for identification and characterization of water or hydrocarbon resource

Correlations Between Variations in Solar EUV and Soft X-Ray Irradiance and Photoelectron Energy Spectra Observed on Mars and Earth

NASA Technical Reports Server (NTRS)

Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

2013-01-01

Solar extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F(10.7) index currently used.

Correlations between variations in solar EUV and soft X-ray irradiance and photoelectron energy spectra observed on Mars and Earth

NASA Astrophysics Data System (ADS)

Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

2013-11-01

extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F10.7 index currently used.

Particle motion in atmospheric boundary layers of Mars and Earth

NASA Technical Reports Server (NTRS)

White, B. R.; Iversen, J. D.; Greeley, R.; Pollack, J. B.

1975-01-01

To study the eolian mechanics of saltating particles, both an experimental investigation of the flow field around a model crater in an atmospheric boundary layer wind tunnel and numerical solutions of the two- and three-dimensional equations of motion of a single particle under the influence of a turbulent boundary layer were conducted. Two-dimensional particle motion was calculated for flow near the surfaces of both Earth and Mars. For the case of Earth both a turbulent boundary layer with a viscous sublayer and one without were calculated. For the case of Mars it was only necessary to calculate turbulent boundary layer flow with a laminar sublayer because of the low values of friction Reynolds number; however, it was necessary to include the effects of slip flow on a particle caused by the rarefied Martian atmosphere. In the equations of motion the lift force functions were developed to act on a single particle only in the laminar sublayer or a corresponding small region of high shear near the surface for a fully turbulent boundary layer. The lift force functions were developed from the analytical work by Saffman concerning the lift force acting on a particle in simple shear flow.

Modeling the effectiveness of shielding in the earth-moon-mars radiation environment using PREDICCS: five solar events in 2012

NASA Astrophysics Data System (ADS)

Quinn, Philip R.; Schwadron, Nathan A.; Townsend, Larry W.; Wimmer-Schweingruber, Robert F.; Case, Anthony W.; Spence, Harlan E.; Wilson, Jody K.; Joyce, Colin J.

2017-08-01

Radiation in the form of solar energetic particles (SEPs) presents a severe risk to the short-term health of astronauts and the success of human exploration missions beyond Earth's protective shielding. Modeling how shielding mitigates the dose accumulated by astronauts is an essential step toward reducing these risks. PREDICCS (Predictions of radiation from REleASE, EMMREM, and Data Incorporating the CRaTER, COSTEP, and other SEP measurements) is an online tool for the near real-time prediction of radiation exposure at Earth, the Moon, and Mars behind various levels of shielding. We compare shielded dose rates from PREDICCS with dose rates from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) onboard the Lunar Reconnaissance Orbiter (LRO) at the Moon and from the Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) during its cruise phase to Mars for five solar events in 2012 when Earth, MSL, and Mars were magnetically well connected. Calculations of the accumulated dose demonstrate a reasonable agreement between PREDICCS and RAD ranging from as little as 2% difference to 54%. We determine mathematical relationships between shielding levels and accumulated dose. Lastly, the gradient of accumulated dose between Earth and Mars shows that for the largest of the five solar events, lunar missions require aluminum shielding between 1.0 g cm-2 and 5.0 g cm-2 to prevent radiation exposure from exceeding the 30-day limits for lens and skin. The limits were not exceeded near Mars.

The Search for Life on Mars - Current Knowledge, Earth Analogues, and Principal Issues

NASA Technical Reports Server (NTRS)

Mumma, Michael J.

2012-01-01

For centuries, the planet Mars has been imagined as a possible abode for life. Serious searches for life's signatures began in the 19th century via ground-based visual astronomy that stimulated a vibrant fantasy literature but little lasting scientific knowledge. Modern scientific inquiry has emphasized the search for chemical signatures of life in the soil and rocks at the planet's surface, and via biomarker gases in the atmosphere. Today, investigations are based on high-resolution spectroscopy at Earth's largest telescopes along with planet orbiting and landed space missions. Methane has assumed central importance in these searches. Living systems produce more than 900/0 of Earth's atmospheric methane; the balance is of geochemical origin. Abundant methane is not expected in an oxidizing atmosphere such as Mars', and its presence would imply recent release - whether biological or geochemical. F or that reason, the quest for methane on Mars has been a continuing thread in the fabric of searches conducted since 1969. I will review aspects of the discovery and distribution of methane on Mars, and will mention ongoing extended searches for clues to its origin and destruction. On Earth, hydrogen (generated via serpentinization or radiolysis of water) provides an important 'fuel' for carbonate-reducing and sulphate-reducing biota (CH4 and H2S producers, respectively). Several such communities are known to reside at depth in continental domains (e.g., Lidy Hot Springs, Idaho; Witwatersrand Basin, S. Africa). If similar conditions exist in favourable locations on Mars, organisms similar to these could likely prosper there. Geologic (abiotic) production will also be mentioned, especially abiotic methane production associated with low-temperature serpentinization (e.g., terrestrial ophiolites). It is vitally important to pursue evidence for geochemical and biological production with equal vigour and intellectual weight lest unwanted and unintended bias contaminate the

Blueberries on Earth and Mars: Some Correlations Between Andean Paleosols, Geothermal Pipes in Navajo Sandstone and Terra Meridiani on Mars

NASA Astrophysics Data System (ADS)

Mahaney, W. C.; Milner, M. W.; Netoff, D. I.; Dohm, J. M.; Sodhi, R. N. S.; Aufreiter, S.; Hancock, R. G. V.; Bezada, M.; Kalm, V.; Malloch, D.

2006-03-01

The origin of "blueberries" on Mars and their relationship to similar concretionary forms on Earth invokes a process of variable redox conditions in underground fluids. The possible role of microorganisms in the origin of bluberries opens an avenue for biological investigations.

Titan South Polar Cloud Burst

NASA Image and Video Library

2009-06-03

This infrared image of Saturn's moon Titan shows a large burst of clouds in the moon's south polar region. These clouds form and move much like those on Earth, but in a much slower, more lingering fashion, new results from NASA's Cassini Spacecraft show. This image is a color composite, with red shown at a 5-micron wavelength, green at 2.7 microns, and blue at 2 microns. An infrared color mosaic is also used as a background image (red at 5 microns, green at 2 microns, blue at 1.3 microns). The images were taken by Cassini's visual and infrared mapping spectrometer during a flyby of Titan on March 26, 2007, known as T27. For a similar view see PIA12004. Titan's southern hemisphere still shows a very active meteorology (the cloud appears in white-reddish tones) even in 2007. According to climate models, these clouds should have faded out since 2005. Scientists have monitored Titan's atmosphere for three-and-a-half years, between July 2004 and December 2007, and observed more than 200 clouds. The way these clouds are distributed around Titan matches scientists' global circulation models. The only exception is timing—clouds are still noticeable in the southern hemisphere while fall is approaching. http://photojournal.jpl.nasa.gov/catalog/PIA12005

Atmospheric Models for Aerocapture

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duval, Aleta; Keller, Vernon W.

2003-01-01

There are eight destinations in the Solar System with sufficient atmosphere for aerocapture to be a viable aeroassist option - Venus, Earth, Mars, Jupiter, Saturn and its moon Titan, Uranus, and Neptune. Engineering-level atmospheric models for four of these targets (Earth, Mars, Titan, and Neptune) have been developed for NASA to support systems analysis studies of potential future aerocapture missions. Development of a similar atmospheric model for Venus has recently commenced. An important capability of all of these models is their ability to simulate quasi-random density perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithms, and for thermal systems design. Similarities and differences among these atmospheric models are presented, with emphasis on the recently developed Neptune model and on planned characteristics of the Venus model. Example applications for aerocapture are also presented and illustrated. Recent updates to the Titan atmospheric model, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Robe entry at Titan, are discussed. Recent updates to the Mars atmospheric model, in support of ongoing Mars aerocapture systems analysis studies, are also presented.

Fluidized-sediment pipes in Gale crater, Mars, and possible Earth analogs

USGS Publications Warehouse

Rubin, David M.; Fairen, A.G.; Frydenvang, J.; Gasnault, O.; Gelfenbaum, Guy R.; Goetz, W.; Grotzinger, J.P.; Le Mouélic, S.; Mangold, N.; Newsom, H.; Oehler, D. Z.; Rapin, W.; Schieber, J.; Wiens, R.C.

2017-01-01

Since landing in Gale crater, the Mars Science Laboratory rover Curiosity has traversed fluvial, lacustrine, and eolian sedimentary rocks that were deposited within the crater ∼3.6 to 3.2 b.y. ago. Here we describe structures interpreted to be pipes formed by vertical movement of fluidized sediment. Like many pipes on Earth, those in Gale crater are more resistant to erosion than the host rock; they form near other pipes, dikes, or deformed sediment; and some contain internal concentric or eccentric layering. These structures provide new evidence of the importance of subsurface aqueous processes in shaping the near-surface geology of Mars.

The effects of solar Reimers η on the final destinies of Venus, the Earth, and Mars

NASA Astrophysics Data System (ADS)

Guo, Jianpo; Lin, Ling; Bai, Chunyan; Liu, Jinzhong

2016-04-01

Our Sun will lose sizable mass and expand enormously when it evolves to the red giant branch phase and the asymptotic giant branch phase. The loss of solar mass will push a planet outward. On the contrary, solar expansion will enhance tidal effects, and tidal force will drive a planet inward. Will our Sun finally engulf Venus, the Earth, and Mars? In the literature, one can find a large number of studies with different points of view. A key factor is that we do not know how much mass the Sun will lose at the late stages. The Reimers η can describe the efficiency of stellar mass-loss and greatly affect solar mass and solar radius at the late stages. In this work, we study how the final destinies of Venus, the Earth, and Mars can be depending on Reimers η chosen. In our calculation, the Reimers η varies from 0.00 to 0.75, with the minimum interval 0.0025. Our results show that Venus will be engulfed by the Sun and Mars will most probably survive finally. The fate of the Earth is uncertain. The Earth will finally be engulfed by the Sun while η <0.4600, and it will finally survive while η ≥ 0.4600. New observations indicate that the average Reimers η for solar-like stars is 0.477. This implies that Earth may survive finally.

Fluvial geomorphology on Earth-like planetary surfaces: A review

PubMed Central

Baker, Victor R.; Hamilton, Christopher W.; Burr, Devon M.; Gulick, Virginia C.; Komatsu, Goro; Luo, Wei; Rice, James W.; Rodriguez, J.A.P.

2017-01-01

Morphological evidence for ancient channelized flows (fluvial and fluvial-like landforms) exists on the surfaces of all of the inner planets and on some of the satellites of the Solar System. In some cases, the relevant fluid flows are related to a planetary evolution that involves the global cycling of a volatile component (water for Earth and Mars; methane for Saturn’s moon Titan). In other cases, as on Mercury, Venus, Earth’s moon, and Jupiter’s moon Io, the flows were of highly fluid lava. The discovery, in 1972, of what are now known to be fluvial channels and valleys on Mars sparked a major controversy over the role of water in shaping the surface of that planet. The recognition of the fluvial character of these features has opened unresolved fundamental questions about the geological history of water on Mars, including the presence of an ancient ocean and the operation of a hydrological cycle during the earliest phases of planetary history. Other fundamental questions posed by fluvial and fluvial-like features on planetary bodies include the possible erosive action of large-scale outpourings of very fluid lavas, such as those that may have produced the remarkable canali forms on Venus; the ability of exotic fluids, such as methane, to create fluvial-like landforms, as observed on Saturn’s moon, Titan; and the nature of sedimentation and erosion under different conditions of planetary surface gravity. Planetary fluvial geomorphology also illustrates fundamental epistemological and methodological issues, including the role of analogy in geomorphological/geological inquiry. PMID:29176917

Nuclear and Radioisotope Propulsion and Power in the Atmosphere of Titan

NASA Astrophysics Data System (ADS)

Widdicombe, T.

A brief history of the use of nuclear fuelled powerplant in space is given along with some working principles of the technology, and recent proposals for spacecraft for the exploration of Titan utilising radioisotope generators are surveyed. Nuclear reaction engines are studied with specific consideration given to their use in Titan's atmosphere, and speculative modifications to one particular spacecraft concept originally conceived of for the exploration of Mars are proposed. A hybrid device producing mechanical power from nuclear decay heat is also suggested for future investigation.

A post-Cassini view of Titan's methane-based hydrologic cycle

NASA Astrophysics Data System (ADS)

Hayes, Alexander G.; Lorenz, Ralph D.; Lunine, Jonathan I.

2018-05-01

The methane-based hydrologic cycle on Saturn's largest moon, Titan, is an extreme analogue to Earth's water cycle. Titan is the only planetary body in the Solar System, other than Earth, that is known to have an active hydrologic cycle. With a surface pressure of 1.5 bar and temperatures of 90 to 95 K, methane and ethane condense out of a nitrogen-based atmosphere and flow as liquids on the moon's surface. Exchange processes between atmospheric, surface and subsurface reservoirs produce methane and ethane cloud systems, as well as erosional and depositional landscapes that have strikingly similar forms to their terrestrial counterparts. Over its 13-year exploration of the Saturn system, the Cassini-Huygens mission revealed that Titan's hydrocarbon-based hydrology is driven by nested methane cycles that operate over a range of timescales, including geologic, orbital (for example, Croll-Milankovitch cycles), seasonal and that of a single convective storm. In this Review Article, we describe the dominant exchange processes that operate over these timescales and present a post-Cassini view of Titan's methane-based hydrologic system.

Wet Mars, Dry Mars

NASA Astrophysics Data System (ADS)

Fillingim, M. O.; Brain, D. A.; Peticolas, L. M.; Yan, D.; Fricke, K. W.; Thrall, L.

2012-12-01

The magnetic fields of the large terrestrial planets, Venus, Earth, and Mars, are all vastly different from each other. These differences can tell us a lot about the interior structure, interior history, and even give us clues to the atmospheric history of these planets. This poster highlights the third in a series of presentations that target school-age audiences with the overall goal of helping the audience visualize planetary magnetic field and understand how they can impact the climatic evolution of a planet. Our first presentation, "Goldilocks and the Three Planets," targeted to elementary school age audiences, focuses on the differences in the atmospheres of Venus, Earth, and Mars and the causes of the differences. The second presentation, "Lost on Mars (and Venus)," geared toward a middle school age audience, highlights the differences in the magnetic fields of these planets and what we can learn from these differences. Finally, in the third presentation, "Wet Mars, Dry Mars," targeted to high school age audiences and the focus of this poster, the emphasis is on the long term climatic affects of the presence or absence of a magnetic field using the contrasts between Earth and Mars. These presentations are given using visually engaging spherical displays in conjunction with hands-on activities and scientifically accurate 3D models of planetary magnetic fields. We will summarize the content of our presentations, discuss our lessons learned from evaluations, and show (pictures of) our hands-on activities and 3D models.

Lab-on-a-Chip Instrument Development for Titan Exploration

NASA Astrophysics Data System (ADS)

Willis, P. A.; Greer, F.; Fisher, A.; Hodyss, R. P.; Grunthaner, F.; Jiao, H.; Mair, D.; Harrison, J.

2009-12-01

This contribution will describe the initial stages of a new ASTID-funded research program initiated in Fall 2009 aimed at lab-on-a-chip system development for astrobiological investigations on Titan. This technology development builds off related work at JPL and Berkeley [1-3] on the ultrasensitive compositional and chiral analysis of amino acids on Mars in order to search for signatures of past or present life. The Mars-focused instrument system utilizes a microcapillary electrophoresis (μCE) system integrated with on-chip perfluoropolyether (PFPE) membrane valves and pumps for automated liquid sample handling, on-chip derivitization of samples with fluorescent tags, dilution, and mixing with standards for data calibration. It utilizes a four-layer wafer stack design with CE channels patterned in glass, along with a PFPE membrane, a pneumatic manifold layer, and a fluidic bus layer. Three pneumatically driven on-chip diaphragm valves placed in series are used to peristaltically pump reagents, buffers, and samples to and from capillary electrophoresis electrode well positions. Electrophoretic separation occurs in the all-glass channels near the base of the structure. The Titan specific lab-on-a-chip system under development here focuses its attention on the unique organic chemistry of Titan. In order to chromatographically separate mixtures of neutral organics such as polycyclic aromatic hydrocarbons (PAHs), the Titan-specific microfluidic platform utilizes the related technique of microcapillary electrochromatography (μCEC). This technique differs from conventional μCE in that microchannels are filled with a porous stationary phase that presents surfaces upon which analyte species can adsorb/desorb. It is this additional surface interaction that enables separations of species critical to the understanding of the astrobiological potential of Titan that are not readily separated by the μCE technique. We have developed two different approaches for the integration

Terraforming the Planets and Climate Change Mitigation on Earth

NASA Astrophysics Data System (ADS)

Toon, O. B.

2008-12-01

Hopefully, purposeful geo-engineering of the Earth will remain a theoretical concept. Of course, we have already inadvertently changed the Earth, and over geologic history life has left an indelible imprint on our planet. We can learn about geo-engineering schemes by reference to Earth history, for example climate changes after volcanic eruptions provide important clues to using sulfates to modify the climate. The terrestrial planets and Titan offer additional insights. For instance, Mars and Venus both have carbon dioxide dominated greenhouses. Both have more than 10 times as much carbon dioxide in their atmospheres as Earth, and both absorb less sunlight than Earth, yet one is much colder than Earth and one is much hotter. These facts provide important insights into carbon dioxide greenhouses that I will review. Mars cools dramatically following planet wide dust storms, and Titan has what is referred to as an anti- greenhouse climate driven by aerosols. These data can be used to reassure us that we can model aerosol caused changes to the climate of a planet, and also provide examples of aerosols offsetting a gas-driven greenhouse effect. People have long considered whether we might make the other planets habitable. While most of the schemes considered belong in the realm of science fiction, it is possible that some schemes might be practical. Terraforming brings to mind a number of issues that are thought provoking, but not so politically charged as geo-engineering. For example: What criteria define habitability, is it enough for people to live in isolated glass enclosures, or do we need to walk freely on the planet? Different creatures have different needs. Is a planet habitable if plants can thrive in the open, or do animals also need to be free? Are the raw materials present on any planet to make it habitable? If not, can we make the materials, or do we have to import them? Is it ethical to change a planetary climate? What if there are already primitive

Characterization of complex organics produced by proton irradiation of simulated Titan atmosphere

NASA Astrophysics Data System (ADS)

Taniuchi, T.; Hosogai, T.; Kaneko, T.; Kobayashi, K.

Titan the biggest satellite of Saturn has dense atmosphere that mainly consists of nitrogen and methane Voyager observation showed the presence of organic haze in Titan atmosphere Some scientists suggested the existence liquid hydrocarbon and water ice on surface Recently Huygens probe sent the analytical data about organic aerosol in Titan atmosphere to the Earth while in the Cassini-Huygens Mission It is supposed that Titan has somewhat similar environments to the primitive Earth so many observations and simulation experiments have been done where mainly UV light or electric discharges are used as energy sources Khare and Sagan reported that the organic materials produced by electric discharges in simulated Titan atmosphere tholin had structure with hydrocarbons nitriles hetero aromatic compounds and so on and that tholin yielded amino acids after hydrolysis They simulated the condition of upper atmosphere of Titan Though cosmic rays are possible effective energy source near the surface on Titan for the formation of organic compounds there were few laboratory simulations of cosmic ray tholin In this study we irradiated proton beam to the mixture of nitrogen and methane to verify the possibile formation of cosmic ray tholin in lower Titan atmosphere A mixture of methane 1-5 and nitrogen balance was irradiated with 3 MeV proton from a van de Graaff accelerator The resulting tholin was analyzed by Pyrolysis Py -GC MS and 1 H NMR to estimate the structure Gel permeation chromatography GPC and

Acetylene-based pathways for prebiotic evolution on Titan

NASA Astrophysics Data System (ADS)

Abbas, O.; Schulze-Makuch, D.

2002-11-01

Due to Titan's reducing atmosphere and lack of an ozone shield, ionizing radiation penetrates the atmosphere creating ions, radicals and electrons that are highly reactive producing versatile chemical species on Titan's surface. We propose that the catalytic hydrogenation of photochemically produced acetylene may be used as simple metabolic pathway by organisms at or near Titan's surface. While the acetylene may undergo this reaction, it can also undertake several other multi-step synthetic schemes that eventually lead to the production of amino acids or other biologically important molecules. Four model synthetic schemes will be described, and their relevance in relation to prebiotic evolution on Earth is discussed.

A Last Look at Titan

NASA Image and Video Library

2017-09-15

As it glanced around the Saturn system one final time, NASA's Cassini spacecraft captured this view of the planet's giant moon Titan. Interest in mysterious Titan was a major motivating factor to return to Saturn with Cassini-Huygens following the Voyager mission flybys of the early 1980s. Cassini and its Huygens probe, supplied by European Space Agency, revealed the moon to be every bit as fascinating as scientists had hoped. These views were obtained by Cassini's narrow-angle camera on Sept. 13, 2017. They are among the last images Cassini sent back to Earth. This natural color view, made from images taken using red, green and blue spectral filters, shows Titan much as Voyager saw it -- a mostly featureless golden orb, swathed in a dense atmospheric haze. An enhanced-color view (Figure 1) adds to this color a separate view taken using a spectral filter (centered at 938 nanometers) that can partially see through the haze. The views were acquired at a distance of 481,000 miles (774,000 kilometers) from Titan. The image scale is about 3 miles (5 kilometers) per pixel. https://photojournal.jpl.nasa.gov/catalog/PIA21890

Titan Lingering Clouds

NASA Image and Video Library

2009-06-03

Lots of clouds are visible in this infrared image of Saturn's moon Titan. These clouds form and move much like those on Earth, but in a much slower, more lingering fashion, new results from NASA's Cassini spacecraft show. Scientists have monitored Titan's atmosphere for three-and-a-half years, between July 2004 and December 2007, and observed more than 200 clouds. The way these clouds are distributed around Titan matches scientists' global circulation models. The only exception is timing—clouds are still noticeable in the southern hemisphere while fall is approaching. Three false-color images make up this mosaic and show the clouds at 40 to 50 degrees mid-latitude. The images were taken by Cassini's visual and infrared mapping spectrometer during a close flyby of Titan on Sept. 7, 2006, known as T17. For a similar view see PIA12005. Each image is a color composite, with red shown at the 2-micron wavelength, green at 1.6 microns, and blue at 2.8 microns. An infrared color mosaic is also used as a background (red at 5 microns, green at 2 microns and blue at 1.3 microns). The characteristic elongated mid-latitude clouds, which are easily visible in bright bluish tones are still active even late into 2006-2007. According to climate models, these clouds should have faded out since 2005. http://photojournal.jpl.nasa.gov/catalog/PIA12004

The magnetic geometry of Titan's induced magnetosphere

NASA Astrophysics Data System (ADS)

Bertucci, C.; Achilleos, N.; Dougherty, M. K.

2011-12-01

As a result of the virtual absence of an intrinsic field at Titan, an induced magnetosphere is formed from the direct interaction between its atmosphere and the plasma environment. Observations at unmagnetized objects such as comets, or planets like Venus and Mars, have shown that the orientation of the magnetic field within an induced magnetosphere is, on average, symmetric with respect to the plane generated by the upstream magnetic field and plasma velocity vectors. Analyses of Voyager and early Cassini magnetometer data around Titan confirm this feature. In this work, we study the efficiency of the background magnetic field-based 'draping coordinate system' (DRAP) introduced in Neubauer et al., [2006] to organize Cassini magnetometer (MAG) measurements within the induced magnetosphere of Titan for all the close flybys of the Prime Mission where MAG data is available. We find that, in general, DRAP coordinates are efficient in organizing the orientation of the draped magnetic field according to the pattern expected for an induced magnetosphere, suggesting that the same system could be used to spatially organize plasma measurements. Departures from this picture are likely related to non stationarity in the upstream flow, fossil fields and, induced currents within Titan's ionosphere and, probably, its interior. REFERENCES: Neubauer, F. M., et al. (2006). Titan's near magnetotail from magnetic field and electron plasma observations and modeling: Cassini flybys TA, TB, and T3. Journal of Geophysical Research, 111(A10), 1-15. doi: 10.1029/2006JA011676.

Bedrock Canyons Carved by the Largest Known Floods on Earth and Mars

NASA Astrophysics Data System (ADS)

Lamb, M. P.; Lapôtre, M. G. A.; Larsen, I. J.; Williams, R. M. E.

2017-12-01

The surface of Earth is a dynamic and permeable interface where the rocky crust is sculpted by ice, wind and water resulting in spectacular mountain ranges, vast depositional basins and environments that support life. These landforms and deposits contain a rich, yet incomplete, record of Earth history that we are just beginning to understand. Some of the most dramatic landforms are the huge bedrock canyons carved by catastrophic floods. On Mars, similar bedrock canyons, known as Outflow Channels, are the most important indicators of large volumes of surface water in the past. Despite their importance and now decades of observations of canyon morphology, we lack a basic understanding of how the canyons formed, which limits our ability to reconstruct flood discharge, duration and water volume. In this presentation I will summarize recent work - using mechanistic numerical models and field observations - that suggests that bedrock canyons carved by megafloods rapidly evolve to a size and shape such that boundary shear stresses just exceed that required to entrain fractured blocks of rock. The threshold shear stress constraint allows for quantitative reconstruction of the largest known floods on Earth and Mars, and implies far smaller discharges than previous methods that assume flood waters fully filled the canyons to high water marks.

Rotation of the Earth, Mars and asteroids: components, techniques and data quality

NASA Astrophysics Data System (ADS)

Souchay, Jean

2004-12-01

We explain in some detail the analytical formulations which enable to modelize both the free and the forced motion of any celestial body taken as rigid or deformable, and we show how they have been applied (with the corresponding level of precision) for the Earth, Mars and the asteroids in general

Review on dielectric properties of rare earth doped barium titanate

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

Ismail, Fatin Adila, E-mail: fatinadilaismail@gmail.com; Osman, Rozana Aina Maulat, E-mail: rozana@unimap.edu.my; Frontier Materials Research, Seriab, 01000 Kangar, Perlis

2016-07-19

Rare earth doped Barium Titanate (BaTiO{sub 3}) were studied due to high permittivity, excellent electrical properties and have wide usage in various applications. This paper reviewed on the electrical properties of RE doped BaTiO{sub 3} (RE: Lanthanum (La), Erbium (Er), Samarium (Sm), Neodymium (Nd), Cerium (Ce)), processing method, phase transition occurred and solid solution range for complete study. Most of the RE doped BaTiO{sub 3} downshifted the Curie temperature (T{sub C}). Transition temperature also known as Curie temperature, T{sub C} where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-dopedmore » BaTiO{sub 3}, Er-doped BaTiO{sub 3}, Sm-doped BaTiO{sub 3}, Nd-doped BaTiO{sub 3} and Ce-doped BaTiO{sub 3} had been proved to increase and the transition temperature or also known as T{sub C} also lowered down to room temperature as for all the RE doped BaTiO{sub 3} except for Er-doped BaTiO{sub 3}.« less

Reorientation Timescales and Pattern Dynamics for Titan's Dunes: Does the Tail Wag the Dog or the Dragon?

NASA Astrophysics Data System (ADS)

Hayes, A. G.; Ewing, R. C.; Cassini Radar Science Team, T.

2011-12-01

^3 migration timescales). In addition, comparisons between spacing and defect density of Titan's dunes and some of the largest fields observed on Earth and Mars reveal that dune patterns on all three planets are geometrically similar, suggesting that growth and organization share common pattern dynamics. Our results suggest that Titan's dunes may react to gross bedform transport averaged over orbital timescales, relaxing the requirement that a single modern wind regime is required to produce the observed pattern.

Low energy trajectories to Mars via gravity assist from Venus to earth

NASA Technical Reports Server (NTRS)

Williams, S. N.; Longuski, J. M.

1991-01-01

The analytical determination of launch dates and proposed trajectories is reviewed with respect to the search for a low-energy trajectory to Mars with gravitational assist from Venus for the years 1995-2024. Both Ballistic and Venus-Earth gravity assist (VEGA) trajectories are calculated with an automated design tool by the authors (1990). The trajectories are modeled as conic sections from one gravitating body to the next, and gravity assist is considered to act impulsively. VEGA trajectories to Mars require similar launch energies for 6 years listed and have moderate arrival C3s, with the lowest C3 requirement in 2015. The flight time and arrival energies of the trajectories are found to be larger than those of ballistic trajectories, but the low-energy launch window makes them desirable for unmanned Mars missions, in particular.

Blueberries on Earth and Mars: Correlations Between Concretions in Navajo Sandstone and Terra Meridiani on Mars.

NASA Astrophysics Data System (ADS)

Mahaney, W. C.; Milner, M. W.; Netoff, D.; Dohm, J.; Kalm, V.; Krinsley, D.; Sodhi, R. N.; Anderson, R. C.; Boccia, S.; Malloch, D.; Kapran, B.; Havics, A.

2008-12-01

Concretionary Fe-Mn-rich nodular authigenic constituents of Jurassic Navajo sandstone (moki marbles) bear a certain relationship to similar concretionary forms ('blueberries') observed on Mars. Their origin on Earth is considered to invoke variable redox conditions with underground fluids penetrating porous quartz-rich sandstone leading to precipitation of hematite and goethite-rich material from solution, generally forming around a central nucleus of fine particles of quartz and orthoclase, recently verified by XRD and SEM-EDS analyses. At the outer rim/inner nucleus boundary, bulbous lobes of fine-grained quartz often invade and fracture the outer rim armored matrix. The bulbous forms are interpreted to result from fluid explusion from the inner concretionary mass, a response to pressure changes accompanying overburden loading. Moki marbles, harder than enclosing rock, often weather out of in situ sandstone outcrops that form a surface lag deposit of varnished marbles that locally resemble desert pavement. The marbles appear morphologically similar to 'blueberries' identified on the martian surface in Terra Meridiani through the MER-1 Opportunity rover. On Earth, redox fluids responsible for the genesis of marbles may have emanated from deep in the crust (often influenced by magmatic processes). These fluids, cooling to ambient temperatures, may have played a role in the genesis of the cemented outer rim of the concretions. The low frequency of fungi filaments in the marbles, contrasts with a high occurrence in Fe-encrusted sands of the Navajo formation [1], indicating that microbial content is of secondary importance in marble genesis relative to the fluctuating influx of ambient groundwater. Nevertheless, the presence of filaments in terrestrial concretions hints at the possibility of discovering fossil/extant life on Mars, and thus should be considered as prime targets for future reconnaissance missions to Mars. 1] Mahaney, W.C., et al. (2004), Icarus, 171, 39-53.

Mars Exploration: Is There Water on Mars? An Educator's Guide with Activities for Physical and Earth and Space Science.

ERIC Educational Resources Information Center

TERC, Cambridge, MA.

This educator's guide discusses whether there is water on the planet Mars. The activities, written for grades 9-12, concern physical, earth, and space sciences. By experimenting with water as it changes state and investigating some effects of air pressure, students not only learn core ideas in physical science but can also deduce the water…

Life on Mars

NASA Technical Reports Server (NTRS)

McKay, Christopher P.; Cuzzi, Jeffrey (Technical Monitor)

1996-01-01

Although the Viking results may indicate that Mars has no life today, the possibility exists that Mars may hold the best record of the events that led to the origin of life. There is direct geomorphological evidence that in the past Mars had large amounts of liquid water on its surface. Atmospheric models would suggest that this early period of hydrological activity was due to the presence of a thick atmosphere and the resulting warmer temperatures. From a biological perspective the existence of liquid water, by itself motivates the question of the origin of life on Mars. From studies of the Earth's earliest biosphere we know that by 3.5 Gyr. ago, life had originated on Earth and reached a fair degree of biological sophistication. Surface activity and erosion on Earth make it difficult to trace the history of life before the 3.5 Gyr timeframe. If Mars did maintain a clement environment for longer than it took for life to originate on Earth, then the question of the origin of life on Mars follows naturally.

Titan's atmosphere and surface in 2026: the AVIATR Titan Airplane Mission

NASA Astrophysics Data System (ADS)

McKay, Chris; Barnes, Jason W.; Lemke, Lawrence; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David; Flasar, F. Michael

2010-04-01

This poster describes the scientific, engineering, and operations planning for a Discovery / New Frontiers class Titan airplane mission, AVIATR (Aerial Vehicle for In-situ and Airborne Titan Reconnaissance). The mission would focus on Titan's surface and atmospheric diversity, using high-resolution imaging, near-infrared spectroscopy, a haze spectrometer, and atmospheric structure measurements. Previous mission studies have elected to use hot-air balloons to achieve similar science goals. These hot-air balloon concepts require the waste heat from inefficient thermocouple-based Radioisotope Thermoelectric Generators (RTGs) for buoyancy. New Advanced Stirling Radioisotope Generators (ASRGs) are much more efficient than RTGs both in terms of power produced per gram of plutonium-238 and the total watts-per-kilogram of the power unit itself. However, they are so efficient that they are much less effective for use in heating a hot-air balloon. Similarly, old-style RTGs produce insufficient specific power for heavier-than-air flight, but the use of 2 ASRGs can support a 120 kg airplane for a long-duration mission at Titan. The AVIATR airplane concept has several advantages in its science capabilities relative to a balloon, including the ability to target any site of interest, remaining on the dayside, stereo and repeat coverage, and easy altitude changes. It also possesses engineering advantages over a balloon like low total mass, a more straightforward deployment sequence, direct-to-Earth communications capability, and a more robust airframe.

GRAM Series of Atmospheric Models for Aeroentry and Aeroassist

NASA Technical Reports Server (NTRS)

Duvall, Aleta; Justus, C. G.; Keller, Vernon W.

2005-01-01

The eight destinations in the Solar System with sufficient atmosphere for either aeroentry or aeroassist, including aerocapture, are: Venus, Earth, Mars, Jupiter, Saturn; Uranus. and Neptune, and Saturn's moon Titan. Engineering-level atmospheric models for four of these (Earth, Mars, Titan, and Neptune) have been developed for use in NASA's systems analysis studies of aerocapture applications in potential future missions. Work has recently commenced on development of a similar atmospheric model for Venus. This series of MSFC-sponsored models is identified as the Global Reference Atmosphere Model (GRAM) series. An important capability of all of the models in the GRAM series is their ability to simulate quasi-random perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithms, and for thermal systems design. Example applications for Earth aeroentry and Mars aerocapture systems analysis studies are presented and illustrated. Current and planned updates to the Earth and Mars atmospheric models, in support of NASA's new exploration vision, are also presented.

Simulating "Mars on Earth"

NASA Technical Reports Server (NTRS)

Clancey, William J.; Clancy, Daniel (Technical Monitor)

2002-01-01

By now, everyone who's heard of the Haughton-Mars Project knows that we travel to Devon Island to learn how people will live and work on Mars. But how do we learn about Mars operations from what happens in the Arctic? We must document our experience--traverses, life in the hab, instrument deployment, communications, and so on. Then we must analyze and formally model what happens. In short, while most scientists are studying the crater, other scientists must be studying the expedition itself. That's what I have done in the past four field seasons. I study field science, both as it naturally occurs at Haughton (unconstrained by a "Mars Sam") and as a constrained experiment using the Flashline Mars Arctic Research Station. During the second week of July 2001, I lived and worked in the hab as part of the Phase 2 crew of six. Besides participating in all activities, I took many photographs and time lapse video. The result of my work will be a computer simulation of how we lived and worked in the hab. It won't be a model of particular people or even my own phase per se, but a pastiche that demonstrates (a proof of concept) that we have appropriate tools for simulating the layout of the hab and daily routines followed by the group and individual scientists. Activities-how people spend their time-are the focus of my observations for building such a simulation model.

Mars Exploration Architecture

NASA Technical Reports Server (NTRS)

Jordan, James F.; Miller, Sylvia L.

2000-01-01

The architecture of NASA's program of robotic Mars exploration missions received an intense scrutiny during the summer months of 1998. We present here the results of that scrutiny, and describe a list of Mars exploration missions which are now being proposed by the nation's space agency. The heart of the new program architecture consists of missions which will return samples of Martian rocks and soil back to Earth for analysis. A primary scientific goal for these missions is to understand Mars as a possible abode of past or present life. The current level of sophistication for detecting markers of biological processes and fossil or extant life forms is much higher in Earth-based laboratories than possible with remotely deployed instrumentation, and will remain so for at least the next decade. Hence, bringing Martian samples back to Earth is considered the best way to search for the desired evidence. A Mars sample return mission takes approximately three years to complete. Transit from Earth to Mars requires almost a single year. After a lapse of time of almost a year at Mars, during which orbital and surface operations can take place, and the correct return launch energy constraints are met, a Mars-to-Earth return flight can be initiated. This return leg also takes approximately one year. Opportunities to launch these 3-year sample return missions occur about every 2 years. The figure depicts schedules for flights to and from Mars for Earth launches in 2003, 2005, 2007 and 2009. Transits for less than 180 deg flight angle, measured from the sun, and more than 180 deg are both shown.

Mars for Earthlings: an analog approach to Mars in undergraduate education.

PubMed

Chan, Marjorie; Kahmann-Robinson, Julia

2014-01-01

Mars for Earthlings (MFE) is a terrestrial Earth analog pedagogical approach to teaching undergraduate geology, planetary science, and astrobiology. MFE utilizes Earth analogs to teach Mars planetary concepts, with a foundational backbone in Earth science principles. The field of planetary science is rapidly changing with new technologies and higher-resolution data sets. Thus, it is increasingly important to understand geological concepts and processes for interpreting Mars data. MFE curriculum is topically driven to facilitate easy integration of content into new or existing courses. The Earth-Mars systems approach explores planetary origins, Mars missions, rocks and minerals, active driving forces/tectonics, surface sculpting processes, astrobiology, future explorations, and hot topics in an inquiry-driven environment. Curriculum leverages heavily upon multimedia resources, software programs such as Google Mars and JMARS, as well as NASA mission data such as THEMIS, HiRISE, CRISM, and rover images. Two years of MFE class evaluation data suggest that science literacy and general interest in Mars geology and astrobiology topics increased after participation in the MFE curriculum. Students also used newly developed skills to create a Mars mission team presentation. The MFE curriculum, learning modules, and resources are available online at http://serc.carleton.edu/marsforearthlings/index.html.

Searching for Life: Early Earth, Mars and Beyond

NASA Technical Reports Server (NTRS)

DesMarais, David J.; Chang, Sherwood (Technical Monitor)

1996-01-01

We might be entering a golden age for exploring life throughout time and space. Rapid gene sequencing will better define our most distant ancestors. The earliest geologic evidence of life is now 3.8 billion years old. Organic matter and submicron-sized morphologies have been preserved in the martian crust for billions of years. Several new missions to Mars are planned, with a high priority on the search for life, past or present. The recent discovery of large extrasolar planets has heightened interest in spacecraft to detect small, earth-like planets. A recent workshop discussed strategies for life detection on such planets. There is much to anticipate in the near future.

Notes on Earth Atmospheric Entry for Mars Sample Return Missions

NASA Technical Reports Server (NTRS)

Rivell, Thomas

2006-01-01

The entry of sample return vehicles (SRVs) into the Earth's atmosphere is the subject of this document. The Earth entry environment for vehicles, or capsules, returning from the planet Mars is discussed along with the subjects of dynamics, aerodynamics, and heat transfer. The material presented is intended for engineers and scientists who do not have strong backgrounds in aerodynamics, aerothermodynamics and flight mechanics. The document is not intended to be comprehensive and some important topics are omitted. The topics considered in this document include basic principles of physics (fluid mechanics, dynamics and heat transfer), chemistry and engineering mechanics. These subjects include: a) fluid mechanics (aerodynamics, aerothermodynamics, compressible fluids, shock waves, boundary layers, and flow regimes from subsonic to hypervelocity; b) the Earth s atmosphere and gravity; c) thermal protection system design considerations; d) heat and mass transfer (convection, radiation, and ablation); e) flight mechanics (basic rigid body dynamics and stability); and f) flight- and ground-test requirements; and g) trajectory and flow simulation methods.

Ion engine propelled Earth-Mars cycler with nuclear thermal propelled transfer vehicle, volume 2

NASA Technical Reports Server (NTRS)

Meyer, Rudolf X.; Baker, Myles; Melko, Joseph

1994-01-01

The goal of this project was to perform a preliminary design of a long term, reusable transportation system between earth and Mars which would be capable of providing both artificial gravity and shelter from solar flare radiation. The heart of this system was assumed to be a Cycler spacecraft propelled by an ion propulsion system. The crew transfer vehicle was designed to be propelled by a nuclear-thermal propulsion system. Several Mars transportation system architectures and their associated space vehicles were designed.

Comparative study of ion cyclotron waves at Mars, Venus and Earth

NASA Astrophysics Data System (ADS)

Wei, H. Y.; Russell, C. T.; Zhang, T. L.; Blanco-Cano, X.

2011-08-01

Ion cyclotron waves are generated in the solar wind when it picks up freshly ionized planetary exospheric ions. These waves grow from the free energy of the highly anisotropic distribution of fresh pickup ions, and are observed in the spacecraft frame with left-handed polarization and a wave frequency near the ion's gyrofrequency. At Mars and Venus and in the Earth's polar cusp, the solar wind directly interacts with the planetary exospheres. Ion cyclotron waves with many similar properties are observed in these diverse plasma environments. The ion cyclotron waves at Mars indicate its hydrogen exosphere to be extensive and asymmetric in the direction of the interplanetary electric field. The production of fast neutrals plays an important role in forming an extended exosphere in the shape and size observed. At Venus, the region of exospheric proton cyclotron wave production may be restricted to the magnetosheath. The waves observed in the solar wind at Venus appear to be largely produced by the solar-wind-Venus interaction, with some waves at higher frequencies formed near the Sun and carried outward by the solar wind to Venus. These waves have some similarity to the expected properties of exospherically produced proton pickup waves but are characterized by magnetic connection to the bow shock or by a lack of correlation with local solar wind properties respectively. Any confusion of solar derived waves with exospherically derived ion pickup waves is not an issue at Mars because the solar-produced waves are generally at much higher frequencies than the local pickup waves and the solar waves should be mostly absorbed when convected to Mars distance as the proton cyclotron frequency in the plasma frame approaches the frequency of the solar-produced waves. In the Earth's polar cusp, the wave properties of ion cyclotron waves are quite variable. Spatial gradients in the magnetic field may cause this variation as the background field changes between the regions in which

ARPS Enabled Titan Rover Concept with Inflatable Wheels

NASA Technical Reports Server (NTRS)

Balint, Tibor S.; Schriener, Timothy M.; Shirley, James H.

2006-01-01

The Decadal Survey identified Titan as one of the top priority science destinations in the large moons category, while NASA's proposed Design Reference Mission Set ranked a Titan in-situ explorer second, after a recommended Europa Geophysical Observer mission. This paper discusses a Titan rover concept, enabled by a single advanced Radioisotope Power System that could provide about 110We (BOL). The concept targets the smaller Flagship or potentially the New Frontiers mission class. This MSL class rover would traverse on four 1.5 m diameter inflatable wheels during its 3 years mission duration and would use as much design and flight heritage as possible to reduce mission cost. Direct to Earth communication would remove the need for a relay orbiter. Details on the strawman instrument payload, and rover subsystems are given for this science driven mission concept. In addition, power system trades between Advanced RTG, TPV, and Advanced Stirling and Brayton Radioisotope Power Systems (RPS) are outlined. While many possible approaches exist for Titan in-situ exploration, the Titan rover concept presented here could provide a scientifically interesting and programmatically affordable solution.

Photochemical studies in low Earth orbit for organic compounds related to small bodies, Titan and Mars. Current and future facilities.

NASA Astrophysics Data System (ADS)

Cottin, H.; Saiagh, K.; Nguyen, D.; Grand, N.; Bénilan, Y.; Cloix, M.; Coll, P.; Gazaux, M.-C.; Fray, N.; Khalaf, D.; Raulin, F.; Stalort, F.; Carrasco, N.; Szopa, C.; Chaput, D.; Bertrand, M.; Westall, F.; Mattioda, A.; Quinn, R.; Ricco, A.; Santos, O.; Baratta, G. A.; Strazzulla, G.; Palumbo, M. E.; Le Postollec, A.; Dobrijevic, M.; Coussot, G.; Vigier, F.; Vandenabeele-Trambouze, O.; Incerti, S.; Berger, T.

2015-01-01

The study of the evolution of organic matter subjected to space conditions, and more specifically to solar photons in the vacuum ultraviolet range (120-200 nm) has been undertaken in low Earth Orbit since the 90's, and implemented on various space platforms. The most recent exposure facilities are BIOPAN outside the Russian automatic capsules FOTON, and EXPOSE-E & -R (1&2) outside the International Space Station. They allow the photolysis of many different samples simultaneously, and provide us with valuable data about the formation and evolution of organic matter in the Solar System (meteorites, comets, Titan's atmosphere, the Martian surface...) and in the Interstellar Medium. They have been used by European teams in the recent past(ORGANIC on BIOPAN V-FOTON M2 and UVolution on BIOPAN VI-FOTON M3, PROCESS on EXPOSE-E, AMINO and ORGANICS on EXPOSE-R), and a new EXPOSE set is currently exposed outside the ISS (PSS on EXPOSE-R2). These existing tools are very valuable; however, they have significant limitations that limit their capabilities and scientific return. One of the most critical issues for current studies is the lack of any in-situ analysis of the evolution of the samples as a function of time. Only two measurements are available for the experiment: one before and one after the exposure. A significant step forward has been achieved with the O/OREOS NASA nanosatellite and the OREOcube ESA project with onboard UV-visible measurements. However, for organic samples, following the evolution of the samples would be more informative and provide greater insight with infrared measurements, which display specific patterns characteristic of major organic functionalities in the mid-infrared range (4000-1000 cm-1).

Aqueous Alteration of Basalts: Earth, Moon, and Mars

NASA Technical Reports Server (NTRS)

Ming, Douglas W.

2007-01-01

The geologic processes responsible for aqueous alteration of basaltic materials on Mars are modeled beginning with our knowledge of analog processes on Earth, i.e., characterization of elemental and mineralogical compositions of terrestrial environments where the alteration and weathering pathways related to aqueous activity are better understood. A key ingredient to successful modeling of aqueous processes on Mars is identification of phases that have formed by those processes. The purpose of this paper is to describe what is known about the elemental and mineralogical composition of aqueous alteration products of basaltic materials on Mars and their implications for specific aqueous environments based upon our knowledge of terrestrial systems. Although aqueous alteration has not occurred on the Moon, it is crucial to understand the behaviors of basaltic materials exposed to aqueous environments in support of human exploration to the Moon over the next two decades. Several methods or indices have been used to evaluate the extent of basalt alteration/weathering based upon measurements made at Mars by the Mars Exploration Rover (MER) Moessbauer and Alpha Particle X-Ray Spectrometers. The Mineralogical Alteration Index (MAI) is based upon the percentage of total Fe (Fe(sub T)) present as Fe(3+) in alteration products (Morris et al., 2006). A second method is the evaluation of compositional trends to determine the extent to which elements have been removed from the host rock and the likely formation of secondary phases (Nesbitt and Young, 1992; Ming et al., 2007). Most of the basalts that have been altered by aqueous processes at the two MER landing sites in Gusev crater and on Meridiani Planum have not undergone extensive leaching in an open hydrolytic system with the exception of an outcrop in the Columbia Hills. The extent of aqueous alteration however ranges from relatively unaltered to pervasively altered materials. Several experimental studies have focused upon

Illumination Invariant Change Detection (iicd): from Earth to Mars

NASA Astrophysics Data System (ADS)

Wan, X.; Liu, J.; Qin, M.; Li, S. Y.

2018-04-01

Multi-temporal Earth Observation and Mars orbital imagery data with frequent repeat coverage provide great capability for planetary surface change detection. When comparing two images taken at different times of day or in different seasons for change detection, the variation of topographic shades and shadows caused by the change of sunlight angle can be so significant that it overwhelms the real object and environmental changes, making automatic detection unreliable. An effective change detection algorithm therefore has to be robust to the illumination variation. This paper presents our research on developing and testing an Illumination Invariant Change Detection (IICD) method based on the robustness of phase correlation (PC) to the variation of solar illumination for image matching. The IICD is based on two key functions: i) initial change detection based on a saliency map derived from pixel-wise dense PC matching and ii) change quantization which combines change type identification, motion estimation and precise appearance change identification. Experiment using multi-temporal Landsat 7 ETM+ satellite images, Rapid eye satellite images and Mars HiRiSE images demonstrate that our frequency based image matching method can reach sub-pixel accuracy and thus the proposed IICD method can effectively detect and precisely segment large scale change such as landslide as well as small object change such as Mars rover, under daily and seasonal sunlight changes.

Mars for Earthlings: An Analog Approach to Mars in Undergraduate Education

PubMed Central

Kahmann-Robinson, Julia

2014-01-01

Abstract Mars for Earthlings (MFE) is a terrestrial Earth analog pedagogical approach to teaching undergraduate geology, planetary science, and astrobiology. MFE utilizes Earth analogs to teach Mars planetary concepts, with a foundational backbone in Earth science principles. The field of planetary science is rapidly changing with new technologies and higher-resolution data sets. Thus, it is increasingly important to understand geological concepts and processes for interpreting Mars data. MFE curriculum is topically driven to facilitate easy integration of content into new or existing courses. The Earth-Mars systems approach explores planetary origins, Mars missions, rocks and minerals, active driving forces/tectonics, surface sculpting processes, astrobiology, future explorations, and hot topics in an inquiry-driven environment. Curriculum leverages heavily upon multimedia resources, software programs such as Google Mars and JMARS, as well as NASA mission data such as THEMIS, HiRISE, CRISM, and rover images. Two years of MFE class evaluation data suggest that science literacy and general interest in Mars geology and astrobiology topics increased after participation in the MFE curriculum. Students also used newly developed skills to create a Mars mission team presentation. The MFE curriculum, learning modules, and resources are available online at http://serc.carleton.edu/marsforearthlings/index.html. Key Words: Mars—Geology—Planetary science—Astrobiology—NASA education. Astrobiology 14, 42–49. PMID:24359289

Titan Casts Revealing Shadow

NASA Astrophysics Data System (ADS)

2004-05-01

diameter, which corresponds to the size of a dime as viewed from about two and a half miles. Illustration of Crab, Titan's Shadow and Chandra Illustration of Crab, Titan's Shadow and Chandra Unlike almost all of Chandra's images which are made by focusing X-ray emission from cosmic sources, Titan's X-ray shadow image was produced in a manner similar to a medical X-ray. That is, an X-ray source (the Crab Nebula) is used to make a shadow image (Titan and its atmosphere) that is recorded on film (Chandra's ACIS detector). Titan's atmosphere, which is about 95% nitrogen and 5% methane, has a pressure near the surface that is one and a half times the Earth's sea level pressure. Voyager I spacecraft measured the structure of Titan's atmosphere at heights below about 300 miles (500 kilometers), and above 600 miles (1000 kilometers). Until the Chandra observations, however, no measurements existed at heights in the range between 300 and 600 miles. Understanding the extent of Titan's atmosphere is important for the planners of the Cassini-Huygens mission. The Cassini-Huygens spacecraft will reach Saturn in July of this year to begin a four-year tour of Saturn, its rings and its moons. The tour will include close flybys of Titan that will take Cassini as close as 600 miles, and the launching of the Huygens probe that will land on Titan's surface. Chandra's X-ray Shadow of Titan Chandra's X-ray Shadow of Titan "If Titan's atmosphere has really expanded, the trajectory may have to be changed." said Tsunemi. The paper on these results has been accepted and is expected to appear in a June 2004 issue of The Astrophysical Journal. Other members of the research team were Haroyoski Katayama (Osaka University), David Burrows and Gordon Garmine (Penn State University), and Albert Metzger (JPL). Chandra observed Titan from 9:04 to 18:46 UT on January 5, 2003, using its Advanced CCD Imaging Spectrometer instrument. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra

An Alternative Humans to Mars Approach: Reducing Mission Mass with Multiple Mars Flyby Trajectories and Minimal Capability Investments

NASA Technical Reports Server (NTRS)

Whitley, Ryan J.; Jedrey, Richard; Landau, Damon; Ocampo, Cesar

2015-01-01

Mars flyby trajectories and Earth return trajectories have the potential to enable lower- cost and sustainable human exploration of Mars. Flyby and return trajectories are true minimum energy paths with low to zero post-Earth departure maneuvers. By emplacing the large crew vehicles required for human transit on these paths, the total fuel cost can be reduced. The traditional full-up repeating Earth-Mars-Earth cycler concept requires significant infrastructure, but a Mars only flyby approach minimizes mission mass and maximizes opportunities to build-up missions in a stepwise manner. In this paper multiple strategies for sending a crew of 4 to Mars orbit and back are examined. With pre-emplaced assets in Mars orbit, a transit habitat and a minimally functional Mars taxi, a complete Mars mission can be accomplished in 3 SLS launches and 2 Mars Flyby's, including Orion. While some years are better than others, ample opportunities exist within a given 15-year Earth-Mars alignment cycle. Building up a mission cadence over time, this approach can translate to Mars surface access. Risk reduction, which is always a concern for human missions, is mitigated by the use of flybys with Earth return (some of which are true free returns) capability.

Strategies for Detecting Biological Molecules on Titan.

PubMed

Neish, Catherine D; Lorenz, Ralph D; Turtle, Elizabeth P; Barnes, Jason W; Trainer, Melissa G; Stiles, Bryan; Kirk, Randolph; Hibbitts, Charles A; Malaska, Michael J

2018-05-02

Saturn's moon Titan has all the ingredients needed to produce "life as we know it." When exposed to liquid water, organic molecules analogous to those found on Titan produce a range of biomolecules such as amino acids. Titan thus provides a natural laboratory for studying the products of prebiotic chemistry. In this work, we examine the ideal locales to search for evidence of, or progression toward, life on Titan. We determine that the best sites to identify biological molecules are deposits of impact melt on the floors of large, fresh impact craters, specifically Sinlap, Selk, and Menrva craters. We find that it is not possible to identify biomolecules on Titan through remote sensing, but rather through in situ measurements capable of identifying a wide range of biological molecules. Given the nonuniformity of impact melt exposures on the floor of a weathered impact crater, the ideal lander would be capable of precision targeting. This would allow it to identify the locations of fresh impact melt deposits, and/or sites where the melt deposits have been exposed through erosion or mass wasting. Determining the extent of prebiotic chemistry within these melt deposits would help us to understand how life could originate on a world very different from Earth. Key Words: Titan-Prebiotic chemistry-Solar system exploration-Impact processes-Volcanism. Astrobiology xx, xxx-xxx.

Mars is the Earth's Only Nearby Early Life Analog, but the Moon is on the Path to Get There

NASA Astrophysics Data System (ADS)

Schmitt, H. H.

2017-02-01

Mars provides a geological integration of the early solar system impacts recorded by the Moon and the contemporaneous water-rich pre-biotic period on Earth. Consideration of human missions to Mars needs to include a return to the Moon to stay.

Mars at Opposition

ERIC Educational Resources Information Center

Riddle, Bob

2010-01-01

On January 29, Mars will reach opposition, a point along its orbit around the Sun where Mars will be directly opposite from the Sun in a two-planet and Sun line-up with the Earth in between. At this opposition, the Earth and Mars will be separated by nearly 100 million km. An opposition is similar to a full Moon in that the planet at opposition…

Evolving earth-based and in-situ satellite network architectures for Mars communications and navigation support

NASA Astrophysics Data System (ADS)

Hastrup, Rolf; Weinberg, Aaron; McOmber, Robert

1991-09-01

Results of on-going studies to develop navigation/telecommunications network concepts to support future robotic and human missions to Mars are presented. The performance and connectivity improvements provided by the relay network will permit use of simpler, lower performance, and less costly telecom subsystems for the in-situ mission exploration elements. Orbiting relay satellites can serve as effective navigation aids by supporting earth-based tracking as well as providing Mars-centered radiometric data for mission elements approaching, in orbit, or on the surface of Mars. The relay satellite orbits may be selected to optimize navigation aid support and communication coverage for specific mission sets.

Evolving earth-based and in-situ satellite network architectures for Mars communications and navigation support

NASA Technical Reports Server (NTRS)

Hastrup, Rolf; Weinberg, Aaron; Mcomber, Robert

1991-01-01

Results of on-going studies to develop navigation/telecommunications network concepts to support future robotic and human missions to Mars are presented. The performance and connectivity improvements provided by the relay network will permit use of simpler, lower performance, and less costly telecom subsystems for the in-situ mission exploration elements. Orbiting relay satellites can serve as effective navigation aids by supporting earth-based tracking as well as providing Mars-centered radiometric data for mission elements approaching, in orbit, or on the surface of Mars. The relay satellite orbits may be selected to optimize navigation aid support and communication coverage for specific mission sets.

Experimental study of heterogeneous organic chemistry induced by far ultraviolet light: Implications for growth of organic aerosols by CH3 addition in the atmospheres of Titan and early Earth

NASA Astrophysics Data System (ADS)

Hong, Peng; Sekine, Yasuhito; Sasamori, Tsutoni; Sugita, Seiji

2018-06-01

Formation of organic aerosols driven by photochemical reactions has been observed and suggested in CH4-containing atmospheres, including Titan and early Earth. However, the detailed production and growth mechanisms of organic aerosols driven by solar far ultraviolet (FUV) light remain poorly constrained. We conducted laboratory experiments simulating photochemical reactions in a CH4sbnd CO2 atmosphere driven by the FUV radiations dominated by the Lyman-α line. In the experiments, we analyzed time variations in thickness and infrared spectra of solid organic film formed on an optical window in a reaction cell. Gas species formed by FUV irradiation were also analyzed and compared with photochemical model calculations. Our experimental results show that the growth rate of the organic film decreases as the CH4/CO2 ratio of reactant gas mixture decreases, and that the decrease becomes very steep for CH4/CO2 < 1. Comparison with photochemical model calculations suggests that polymerizations of gas-phase hydrocarbons, such as polyynes and aromatics, cannot account for the growth rate of the organic film but that the addition reaction of CH3 radicals onto the organic film with the reaction probability around 10-2 can explain the growth rate. At CH4/CO2 < 1, etching by O atom formed by CO2 photolysis would reduce or inhibit the growth of the organic film. Our results suggest that organic aerosols would grow through CH3 addition onto the surface during the precipitation of aerosol particles in the middle atmosphere of Titan and early Earth. On Titan, effective CH3 addition would reduce C2H6 production in the atmosphere. On early Earth, growth of aerosol particles would be less efficient than those on Titan, possibly resulting in small-sized monomers and influencing UV shielding.

Solar Electric and Chemical Propulsion for a Titan Mission

NASA Technical Reports Server (NTRS)

Cupples, Michael; Green, Shaun E.; Donahue, Benjamin B.; Coverstone, Victoria L.

2005-01-01

Systems analyses were performed for a Titan Explorer Mission characterized by Earth-Saturn transfer stages using solar electric power generation and propulsion systems for primary interplanetary propulsion, and chemical propulsion for capture at Titan. An examination of a range of system factors was performed to determine their effect on the payload delivery capability to Titan. The effect of varying launch vehicle type, solar array power level, ion thruster number, specific impulse, trip time, and Titan capture stage chemical propellant choice was investigated. The major purpose of the study was to demonstrate the efficacy of applying advanced ion propulsion system technologies like NASA's Evolutionary Xenon Thruster (NEXT), coupled with state-of-the-art (SOA) and advanced chemical technologies to a Flagship class mission. This study demonstrated that a NASA Design Reference Mission (DRM) payload of 406 kg could be successfully delivered to Titan using the baseline advanced ion propulsion system in conjunction with SOA chemical propulsion for Titan capture. In addition, the SEPS/Chemical system of this study is compared to an all- chemical NASA DRM mission. Results showed that the NEXT- based SEPS/Chemical system was able to deliver the required payload to Titan in 5 years less transfer time and on a smaller launch vehicle than the SOA chemical option.

Seismic generated infrasounds on Telluric Planets: Modeling and comparisons between Earth, Venus and Mars

NASA Astrophysics Data System (ADS)

Lognonne, P. H.; Rolland, L.; Karakostas, F. G.; Garcia, R.; Mimoun, D.; Banerdt, W. B.; Smrekar, S. E.

2015-12-01

Earth, Venus and Mars are all planets in which infrasounds can propagate and interact with the solid surface. This leads to infrasound generation for internal sources (e.g. quakes) and to seismic waves generations for atmospheric sources (e.g. meteor, impactor explosions, boundary layer turbulences). Both the atmospheric profile, surface density, atmospheric wind and viscous/attenuation processes are however greatly different, including major differences between Mars/Venus and Earth due to the CO2 molecular relaxation. We present modeling results and compare the seismic/acoustic coupling strength for Earth, Mars and Venus. This modeling is made through normal modes modelling for models integrating the interior, atmosphere, both with realistic attenuation (intrinsic Q for solid part, viscosity and molecular relaxation for the atmosphere). We complete these modeling, made for spherical structure, by integration of wind, assuming the later to be homogeneous at the scale of the infrasound wavelength. This allows us to compute either the Seismic normal modes (e.g. Rayleigh surface waves), or the acoustic or the atmospheric gravity modes. Comparisons are done, for either a seismic source or an atmospheric source, on the amplitude of expected signals as a function of distance and frequency. Effects of local time are integrated in the modeling. We illustrate the Rayleigh waves modelling by Earth data (for large quakes and volcanoes eruptions). For Venus, very large coupling can occur at resonance frequencies between the solid part and atmospheric part of the planet through infrasounds/Rayleigh waves coupling. If the atmosphere reduced the Q (quality coefficient) of Rayleigh waves in general, the atmosphere at these resonance soffers better propagation than Venus crust and increases their Q. For Mars, Rayleigh waves excitations by atmospheric burst is shown and discussed for the typical yield of impacts. The new data of the Nasa INSIGHT mission which carry both seismic and

Risk analysis of earth return options for the Mars rover/sample return mission

NASA Technical Reports Server (NTRS)

1988-01-01

Four options for return of a Mars surface sample to Earth were studied to estimate the risk of mission failure and the risk of a sample container breach that might result in the release of Martian life forms, should such exist, in the Earth's biosphere. The probabilities calculated refer only to the time period from the last midcourse correction burn to possession of the sample on Earth. Two extreme views characterize this subject. In one view, there is no life on Mars, therefore there is no significant risk and no serious effort is required to deal with back contamination. In the other view, public safety overrides any desire to return Martian samples, and any risk of damaging contamination greater than zero is unacceptable. Zero risk requires great expense to achieve and may prevent the mission as currently envisioned from taking place. The major conclusion is that risk of sample container breach can be reduced to a very low number within the framework of the mission as now envisioned, but significant expense and effort, above that currently planned is needed. There are benefits to the public that warrant some risk. Martian life, if it exists, will be a major discovery. If it does not, there is no risk.

Poster 17: Methane storms as a driver of Titan's dune orientation.

NASA Astrophysics Data System (ADS)

Charnay, Benjamin; Barth, Erika; Rafkin, Scot; Narteau, Clement; Lebonnois, Sebastien; Rodriguez, Sebastien; Courech Du Pont, Sylvain; Lucas, Antoine

2016-06-01

Titan's equatorial regions are covered by eastward oriented linear dunes [1,2]. This direction is opposite to mean surface winds simulated by Global Climate Models (GCMs) at these latitudes, oriented westward as trade winds on Earth. We propose that Titan's dune orientation is actually determined by equinoctial tropical methane storms producing a coupling with superrotation and dune formation [3]. Using meso-scale simulations of convective methane clouds [4] with a GCM wind profile featuring the superrotation [5,6], we show that Titan's storms should produce fast eastward gust fronts above the surface. Such gusts dominate the aeolian transport. Using GCM wind calculations and analogies with terrestrial dune fields [7], we show that Titan's dune propagation occurs eastward under these conditions. Finally, this scenario combining global circulation winds and methane storms can explain other major features of Titan's dunes as the divergence from the equator or the dune size and spacing. It also implies an equatorial origin of Titan's dune sand and a possible occurence of dust storms.

An assessment of crater erosional histories on the Earth and Mars using digital terrain models.

NASA Astrophysics Data System (ADS)

Paul, R. L.; Muller, J.-P.; Murray, J. B.

The research will examine quantitatively the geomorphology of both Terrestrial and Martian craters. The erosional and sub-surface processes will be investigated to understand how these affect a crater's morphology. For example, the Barringer crater in Arizona has an unusual shape. The Earth has a very high percentage of water both in the atmosphere as clouds or rain and under the surface. The presence of water will therefore affect a crater's formation and its subsequent erosional modification. On Mars there is little or no water present currently, though recent observations suggest there may be near-surface ice in some areas. How do craters formed in the Martian environment therefore differ from Terrestrial ones? How has the structure of Martian craters changed in areas of possible fluvial activity? How does the surface material affect crater formation? How does the Earth's fluvial activity affect a crater's evolution? At present, four measurements of circularity have been used to describe a crater (Murray & Guest, 1972). These parameters will be re-examined to see how effectively they describe Terrestrial and Martian craters using high resolution DTMs which were not available at the time of the original study. The model described by Forsberg-Taylor et al. 2004, and others will also be applied to results obtained from the chosen craters to assess how effectively these craters are described. Both hypsometric curves and hydrological analysis will be used to assess crater evolution. A suitable criterion for the selection of Terrestrial and Martian craters is essential for this type of research. Terrestrial craters have been selected in arid or semi-arid terrain with crater diameters larger than one kilometre. Craters less than five million years old would be ideal. However, this was too restrictive and so a variety of crater ages have had to be used. Eight terrestrial craters have been selected in arid or semi-arid areas for study, using the Earth Impact Database and

Mars to earth optical communication link for the proposed Mars Sample Return mission roving vehicle

NASA Astrophysics Data System (ADS)

Sipes, Donald L., Jr.

The Mars Sample Return (MSR) mission planed for 1989 will deploy a rover from its landing craft to survey the Martian surface. During traversals of the rover from one site to the next in search of samples, three-dimensional images from a pair of video cameras will be transmitted to earth; the terrestrial operators will then send back high level direction commands to the rover. Attention is presently given to the effects of wind and dust on communications, the architecture of the optical communications package, and the identification of technological areas requiring further development for MSR incorporation.

A Saturnian gas ring and the recycling of Titan's atmosphere

NASA Technical Reports Server (NTRS)

Mcdonough, T. R.; Brice, N. M.

1973-01-01

Atoms which escape Titan's atmosphere are unlikely to possess escape velocity from Saturn and can orbit the planet until lost by ionization or collision with Titan. It is predicted that a toroidal ring of between 1 and 1,000 atoms or molecules per cubic centimeter exists around Saturn at a distance of about 10 times the radius of the visible rings. This torus may be detectable from earth orbit and detection or nondetection of it may provide some information about the presence or absence of a Saturnian magnetic field, and the exospheric temperature and atmospheric escape rate of Titan. It is estimated that, if Titan has a large exosphere, 97% or more of the escaping atoms can be recaptured by Titan, thereby decreasing the effective net atmospheric loss rate by up to two orders of magnitude. It is shown that, if Saturn has a magnetic field comparable to Jupiter's the magnetospheric plasma can supply Titan with hydrogen at a rate comparable to the loss rates in some of the models of Trafton (1972) and Sagan (1973).

A Martian Telecommunications Network: UHF Relay Support of the Mars Exploration Rovers by the Mars Global Surveyor, Mars Odyssey, and Mars Express Orbiters

NASA Technical Reports Server (NTRS)

Edwards, Charles D., Jr.; Barbieri, A.; Brower, E.; Estabrook, P.; Gibbs, R.; Horttor, R.; Ludwinski, J.; Mase, R.; McCarthy, C.; Schmidt, R.;

LIDAR technology for measuring trace gases on Mars and Earth

NASA Astrophysics Data System (ADS)

Riris, H.; Abshire, J. B.; Graham, Allan; Hasselbrack, William; Rodriguez, Mike; Sun, Xiaoli; Weaver, Clark; Mao, Jianping; Kawa, Randy; Li, Steve; Numata, Kenji; Wu, Stewart

2017-11-01

greenhouse gas and called for a mission to measure CO2, CO and CH4. Methane has absorptions in the mid-infrared (3.3 um) and the near infrared (1.65 um). The 3.3 um spectral region is ideal for planetary (Mars) Methane monitoring, but unfortunately is not suitable for earth monitoring since the Methane absorption lines are severely interfered with by water. The near infra-red overtones of Methane at 1.65 um are relatively free of interference from other atmospheric species and are suitable for Earth observations. The methane instrument uses Optical Parametric Generation (OPG) along with sensitive detectors to achieve the necessary sensitivity. Our instrument generates and detects tunable laser signals in the 3.3 or 1.65 um spectral regions with different detectors in order to measure methane on Earth or Mars. For Mars, the main interest in methane is its importance as a biogenic marker.

Water and Life on Mars

NASA Technical Reports Server (NTRS)

McKay, Christopher P.; DeVincenzi, Donald (Technical Monitor)

2000-01-01

Mars appears to be cold dry and dead world. However there is good evidence that early in its history it had liquid water, more active volcanism, and a thicker atmosphere. Mars had this earth-like environment over three and a half billion years ago, during the same time that life appeared on Earth. The main question in the exploration of Mars then is the search for a independent origin of life on that planet. Ecosystems in cold, dry locations on Earth - such as the Antarctic - provide examples of how life on Mars might have survived and where to look for fossils. Although the Viking results may indicate that Mars has no life today, there is direct geomorphological evidence that, in the past, Mars had large amounts of liquid water on its surface - possibly due to a thicker atmosphere. From a biological perspective the existence of liquid water, by itself motivates the question of the origin of life on Mars. One of the martian meteorites dates back to this early period and may contain evidence consistent with life. From studies of the Earth's earliest biosphere we know that by 3.5 Gyr. ago, life had originated on Earth and reached a fair degree of biological sophistication. Surface activity and erosion on Earth make it difficult to trace the history of life before the 3.5 Gyr timeframe. Ecosystems in cold, dry locations on Earth - such as the Antarctic - provide examples of how life on Mars might have survived and where to look for fossils.

Near-Earth Phase Risk Comparison of Human Mars Campaign Architectures

NASA Technical Reports Server (NTRS)

Manning, Ted A.; Nejad, Hamed S.; Mattenberger, Chris

2013-01-01

A risk analysis of the launch, orbital assembly, and Earth-departure phases of human Mars exploration campaign architectures was completed as an extension of a probabilistic risk assessment (PRA) originally carried out under the NASA Constellation Program Ares V Project. The objective of the updated analysis was to study the sensitivity of loss-of-campaign risk to such architectural factors as composition of the propellant delivery portion of the launch vehicle fleet (Ares V heavy-lift launch vehicle vs. smaller/cheaper commercial launchers) and the degree of launcher or Mars-bound spacecraft element sparing. Both a static PRA analysis and a dynamic, event-based Monte Carlo simulation were developed and used to evaluate the probability of loss of campaign under different sparing options. Results showed that with no sparing, loss-of-campaign risk is strongly driven by launcher count and on-orbit loiter duration, favoring an all-Ares V launch approach. Further, the reliability of the all-Ares V architecture showed significant improvement with the addition of a single spare launcher/payload. Among architectures utilizing a mix of Ares V and commercial launchers, those that minimized the on-orbit loiter duration of Mars-bound elements were found to exceed the reliability of no spare all-Ares V campaign if unlimited commercial vehicle sparing was assumed

GEMINI-TITAN (GT)-3 - EARTH- SKY VIEW

NASA Image and Video Library

1965-03-23

S65-18740 (23 March 1965) --- Astronaut John W. Young took this picture during the second orbit of the Gemini-Titan 3 three-orbit mission as the spacecraft "Molly Brown" passed over Northern Mexico at an altitude of 90 miles. The light-brown circular area at the lower right is the Sonoran Desert. The lower portion of the picture is Mexico, and the upper part is California. Young used a hand-held modified 70mm Hasselblad camera with color film. The lens setting was 250th of a second at f/11.

Synthetic biology meets bioprinting: enabling technologies for humans on Mars (and Earth).

PubMed

Rothschild, Lynn J

2016-08-15

Human exploration off planet is severely limited by the cost of launching materials into space and by re-supply. Thus materials brought from Earth must be light, stable and reliable at destination. Using traditional approaches, a lunar or Mars base would require either transporting a hefty store of metals or heavy manufacturing equipment and construction materials for in situ extraction; both would severely limit any other mission objectives. Long-term human space presence requires periodic replenishment, adding a massive cost overhead. Even robotic missions often sacrifice science goals for heavy radiation and thermal protection. Biology has the potential to solve these problems because life can replicate and repair itself, and perform a wide variety of chemical reactions including making food, fuel and materials. Synthetic biology enhances and expands life's evolved repertoire. Using organisms as feedstock, additive manufacturing through bioprinting will make possible the dream of producing bespoke tools, food, smart fabrics and even replacement organs on demand. This new approach and the resulting novel products will enable human exploration and settlement on Mars, while providing new manufacturing approaches for life on Earth. © 2016 The Author(s).

Synthetic biology meets bioprinting: enabling technologies for humans on Mars (and Earth)

PubMed Central

Rothschild, Lynn J.

2016-01-01

Human exploration off planet is severely limited by the cost of launching materials into space and by re-supply. Thus materials brought from Earth must be light, stable and reliable at destination. Using traditional approaches, a lunar or Mars base would require either transporting a hefty store of metals or heavy manufacturing equipment and construction materials for in situ extraction; both would severely limit any other mission objectives. Long-term human space presence requires periodic replenishment, adding a massive cost overhead. Even robotic missions often sacrifice science goals for heavy radiation and thermal protection. Biology has the potential to solve these problems because life can replicate and repair itself, and perform a wide variety of chemical reactions including making food, fuel and materials. Synthetic biology enhances and expands life's evolved repertoire. Using organisms as feedstock, additive manufacturing through bioprinting will make possible the dream of producing bespoke tools, food, smart fabrics and even replacement organs on demand. This new approach and the resulting novel products will enable human exploration and settlement on Mars, while providing new manufacturing approaches for life on Earth. PMID:27528764

Life on Titan

NASA Astrophysics Data System (ADS)

Potashko, Oleksandr

nuclear winter. These events are known as extinctions or ice ages. The crust of a planet of the Earth group is formed at the outer edge of the body. The planets after asteroid belt like Jupiter or Saturn probably form their “crusts” in the centre of the body. Due to we may see internal kitchen of element forming in detail. This processes lead to the organic life, which we may detect at the atmospheres of Jupiter, Saturn, Neptune, and Pluto. But their satellites look like earth planet group - with outer crust. Huygens considered that God's wisdom and providence is clearest in the creation of life, and Earth holds no privileged position in the heavens that life must be universal. “Huygens” helps find life on Titan

Liftoff of Gemini-Titan 3 mission

NASA Image and Video Library

1965-03-23

S65-14150 (23 March 1965) --- Launch view of the Gemini-Titan 3 mission. The GT-3 liftoff was at 9:24 a.m. (EST) on March 23, 1965. The Gemini-3 spacecraft "Molly Brown" carried astronauts Virgil I. Grissom, command pilot, and John W. Young, pilot, on three orbits of Earth.

Model of Mars-Bound MarCO CubeSat

NASA Image and Video Library

2015-06-12

Engineers for NASA's MarCO technology demonstration display a full-scale mechanical mock-up of the small craft in development as part of NASA's next mission to Mars. Mechanical engineer Joel Steinkraus and systems engineer Farah Alibay are on the team at NASA's Jet Propulsion Laboratory, Pasadena, California, preparing twin MarCO (Mars Cube One) CubeSats for a March 2016 launch. MarCO is the first interplanetary mission using CubeSat technologies for small spacecraft. The briefcase-size MarCO twins will ride along on an Atlas V launch vehicle lifting off from Vandenberg Air Force Base, California, with NASA's next Mars lander, InSight. The mock-up in the photo is in a configuration to show the deployed position of components that correspond to MarCO's two solar panels and two antennas. During launch, those components will be stowed for a total vehicle size of about 14.4 inches (36.6 centimeters) by 9.5 inches (24.3 centimeters) by 4.6 inches (11.8 centimeters). After launch, the two MarCO CubeSats and InSight will be navigated separately to Mars. The MarCO twins will fly past the planet in September 2016 just as InSight is descending through the atmosphere and landing on the surface. MarCO is a technology demonstration mission to relay communications from InSight to Earth during InSight's descent and landing. InSight communications during that critical period will also be recorded by NASA's Mars Reconnaissance Orbiter for delayed transmission to Earth. InSight -- an acronym for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport -- will study the interior of Mars to improve understanding of the processes that formed and shaped rocky planets, including Earth. After launch, the MarCO twins and InSight will be navigated separately to Mars. Note: After thorough examination, NASA managers have decided to suspend the planned March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission

Orbital Drivers of Climate Change on Earth and Mars

NASA Astrophysics Data System (ADS)

Zent, A. P.

Oscillations of orbital elements and spin axis orientation affect the climate of both Earth and Mars by redistributing solar power both latitudinally and seasonally, often resulting in secondary changes in reflected and emitted radiation (radiative forcing). Multiple feedback loops between different climatic elements operate on both planets, with the result that climate response is generally nonlinear with simple changes in solar energy. Both insolation history and geochemical climate proxies can be treated as time series data, and analyzed in terms of component frequencies. The correspondence between frequencies measured in climate proxies and orbital oscillations is the key to relating orbital cause and climatic effect. Discussions of both Earth and Mars focus on the last 5-10 m.y., because this is the period in which the orbital history and geologic record are best understood. The terrestrial climate is an extraordinarily complex system, and a vast amount of data is available for analysis. While the geologic record strongly supports the role of Milankovitch cycles as the underlying cause of glacial cycles, orbitally driven insolation changes alone cannot explain the observations in detail. Early Pleistocene glacial cycles responded linearly to the 41-k.y. oscillations in obliquity. However, over the last 1 m.y., glacial/interglacial oscillations have become more extreme as the climate has cooled. Long cooling intervals marked by an oscillating buildup of ice sheets are now followed by brief, intense periods of warming. At the same time, glacial/interglacial cycles have shifted from 41 k.y. to ~100 k.y. No such changes occurred in the solar forcing due to orbital oscillations. While orbital oscillations still appear to pace glacial cycles, their subtle interplay with ice-sheet dynamics and shifts in ocean circulation have come to dominate the late Pleistocene climate system. In contrast to Earth, the martian climate is ostensibly a much simpler system about which

Titan Mystery Clouds

NASA Image and Video Library

2016-12-21

atmospheric features over the entire observation period and ISS consistently detects surface features with just a few localized clouds. The answer to what could be causing the discrepancy appears to lie with Titan's hazy atmosphere, which is much easier to see through at the longer infrared wavelengths that VIMS is sensitive to (up to 5 microns) than at the shorter, near-infrared wavelength used by ISS to image Titan's surface and lower atmosphere (0.94 microns). High, thin cirrus clouds that are optically thicker than the atmospheric haze at longer wavelengths, but optically thinner than the haze at the shorter wavelength of the ISS observations, could be detected by VIMS and simultaneously lost in the haze to ISS -- similar to trying to see a thin cloud layer on a hazy day on Earth. This phenomenon has not been seen again since July 2016, but Cassini has several more opportunities to observe Titan over the last months of the mission in 2017, and scientists will be watching to see if and how the weather changes. These two images were taken as part of the T120 flyby on June 7 (VIMS) and 8 (ISS), 2016. The distance to Titan was about 28,000 miles (45,000 kilometers) for the VIMS image and about 398,000 miles (640,000 kilometers) for the ISS image. The VIMS image has been processed to enhance the visibility of the clouds; in this false-color view, clouds appear nearly white, atmospheric haze is pink, and surface areas would appear green. http://photojournal.jpl.nasa.gov/catalog/PIA21054

Comparing morphologies of drainage basins on Mars and Earth using integral-geometry and neural maps

NASA Technical Reports Server (NTRS)

Stepinski, T. F.; Coradetti, S.

2004-01-01

We compare morphologies of drainage basins on Mars and Earth in order to confine the formation process of Martian valley networks. Basins on both planets are computationally extracted from digital topography. Integral-geometry methods are used to represent each basin by a circularity function that encapsulates its internal structure. The shape of such a function is an indicator of the style of fluvial erosion. We use the self-organizing map technique to construct a similarity graph for all basins. The graph reveals systematic differences between morphologies of basins on the two planets. This dichotomy indicates that terrestrial and Martian surfaces were eroded differently. We argue that morphologies of Martian basins are incompatible with runoff from sustained, homogeneous rainfall. Fluvial environments compatible with observed morphologies are discussed. We also construct a similarity graph based on the comparison of basins hypsometric curves to demonstrate that hypsometry is incapable of discriminating between terrestrial and Martian basins. INDEX TERMS: 1824 Hydrology: Geomorphology (1625); 1886 Hydrology: Weathering (1625); 5415 Planetology: Solid Surface Planets: Erosion and weathering; 6225 Planetology: Solar System Objects Mars. Citation: Stepinski, T. F., and S. Coradetti (2004), Comparing morphologies of drainage basins on Mars and Earth using integral-ge

The PROCESS experiment: an astrochemistry laboratory for solid and gaseous organic samples in low-earth orbit.

PubMed

Cottin, Hervé; Guan, Yuan Yong; Noblet, Audrey; Poch, Olivier; Saiagh, Kafila; Cloix, Mégane; Macari, Frédérique; Jérome, Murielle; Coll, Patrice; Raulin, François; Stalport, Fabien; Szopa, Cyril; Bertrand, Marylène; Chabin, Annie; Westall, Frances; Chaput, Didier; Demets, René; Brack, André

2012-05-01

The PROCESS (PRebiotic Organic ChEmistry on the Space Station) experiment was part of the EXPOSE-E payload outside the European Columbus module of the International Space Station from February 2008 to August 2009. During this interval, organic samples were exposed to space conditions to simulate their evolution in various astrophysical environments. The samples used represent organic species related to the evolution of organic matter on the small bodies of the Solar System (carbonaceous asteroids and comets), the photolysis of methane in the atmosphere of Titan, and the search for organic matter at the surface of Mars. This paper describes the hardware developed for this experiment as well as the results for the glycine solid-phase samples and the gas-phase samples that were used with regard to the atmosphere of Titan. Lessons learned from this experiment are also presented for future low-Earth orbit astrochemistry investigations.

Effect of gravity on terminal particle settling velocity on Moon, Mars and Earth

NASA Astrophysics Data System (ADS)

Kuhn, Nikolaus J.

2013-04-01

Gravity has a non-linear effect on the settling velocity of sediment particles in liquids and gases due to the interdependence of settling velocity, drag and friction. However, StokeśLaw, the common way of estimating the terminal velocity of a particle moving in a gas of liquid assumes a linear relationship between terminal velocity and gravity. For terrestrial applications, this "error" is not relevant, but it may strongly influence the terminal velocity achieved by settling particles on Mars. False estimates of these settling velocities will, in turn, affect the interpretation of particle sizes observed in sedimentary rocks on Mars. Wrong interpretations may occur, for example, when the texture of sedimentary rocks is linked to the amount and hydraulics of runoff and thus ultimately the environmental conditions on Mars at the time of their formation. A good understanding of particle behaviour in liquids on Mars is therefore essential. In principle, the effect of lower gravity on settling velocity can also be achieved by reducing the difference in density between particle and gas or liquid. However, the use of such analogues simulating the lower gravity on Mars on Earth is creates other problems because the properties (i.e. viscosity) and interaction of the liquids and sediment (i.e. flow around the boundary layer between liquid and particle) differ from those of water and mineral particles. An alternative for measuring the actual settling velocities of particles under Martian gravity, on Earth, is offered by placing a settling tube on a reduced gravity flight and conduct settling tests within the 20 to 25 seconds of Martian gravity that can be simulated during such a flight. In this presentation we report the results of such a test conducted during a reduced gravity flight in November 2012. The results explore the strength of the non-linearity in the gravity-settling velocity relationship for terrestrial, lunar and Martian gravity.

A FUSE Search for Argon on Titan

NASA Astrophysics Data System (ADS)

Gladstone, G. R.; Link, R.; Stern, S. A.; Festou, M.; Waite, J. H.

2002-09-01

The origin of Titan's thick nitrogen and methane atmosphere is a compelling enigma. One key and still missing observable concerns the abundances of noble gases in general, and argon in particular. Detection of sufficient argon could indicate that the N2 and CO now found in the atmosphere came in with ice during Titan's accretion. Alternatively, if there is very little argon, then we have to turn to models starting with frozen ammonia, methane and water ice, indicating a more important role for the Saturn sub-nebula, and requiring subsequent modification by photochemistry. Current estimates on the fraction of argon in Titan's atmosphere are crude, and based only on indirect evidence, and range up to 25%. On Sept. 21, 2000, using the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite, we performed an observation of Titan to search for argon and to make a survey of Titan's dayglow in the 90--115 nm FUSE bandpass. No emissions were found in the 18 ks exposure, although only 7.4 ks were obtained when FUSE was in Earth's shadow where terrestrial airglow contamination is minimal. While no Ar, N, or N2 emissions were detected, 2-σ upper limits of 4 R (for Ar 104.8 nm) and 20 R (for N 113.4 nm) are found using the best of the FUSE data. There is a bump on the terrestrial geocorona H Lyβ emission at 102.5 nm which may be due to Titan and a Titan Torus. The signal in the bump is about 400 R. Model estimates suggest that the Lyβ brightness of Titan should be about 20 R and the Titan Torus in the 30--700 R range. For an assumed argon abundance of 5% the 104.8 nm emission is predicted to be 7 R, so the argon estimate is constraining already. The nitrogen estimate is very close to the model expectation of 15 R. An accurate determination of the abundance of argon on Titan would be useful in preparing for the arrival of the Cassini orbiter and Huygens probe at the Saturn system, so further FUSE observations of Titan are planned. We gratefully acknowledge support from NASA

Global Topography of Titan from Cassini RADAR Data (Invited)

NASA Astrophysics Data System (ADS)

Lorenz, R. D.; Cassini RADAR Team

2010-12-01

Cassini RADAR data are used to construct a global, albeit sparsely-sampled, topography map, and to generate a hypsometric profile to compare with other planetary bodies. Titan’s hypsogram is unimodal and strikingly narrow compared with the terrestrial planets. To investigate topographic extremes, a novel variant on the classic hypsogram is introduced, with a logarithmic abscissa to highlight mountainous terrain. In such a plot, the top of the terrestrial hypsogram is quite distinct from those of Mars and Venus due to the ‘glacial buzz-saw’ that clips terrestrial topography above the snowline. In contrast to the positive skew seen in other hypsograms, with a long tail of positive relief due to mountains, there is an indication (weak, given the limited data for Titan so far) that the Titan hypsogram appears slightly negatively skewed, suggesting a significant population of unfilled depressions. Limited data permit only a simplistic comparison of Titan topography with other icy satellites but we find that the standard deviation of terrain height (albeit at different scales) is similar to those of Ganymede and Europa. The topography of terrestrial planets is sampled with the same coverage that we have for Titan to gauge what as-yet-undiscovered topographic surprises may yet be hidden by Titan’s haze.

Ridge of Jagged Peaks on Titan

NASA Image and Video Library

2016-07-29

This synthetic-aperture radar image was obtained by NASA's Cassini spacecraft during its T-120 pass over Titan's southern latitudes on June 7, 2016. The area shown here measures about 40 by 60 miles (70 by 100 kilometers) and is centered at about 60 degrees south latitude, 130 degrees west longitude. Radar illuminates the scene from the left at a 28-degree incidence angle. At the center of the image is a bright feature oriented from upper left to lower right. This is interpreted to be a long ridge with jagged peaks, likely created by methane rainfall erosion. Some of the individual peaks rise about 2,400 feet (800 meters) above the valley floor. The ridge has a considerably gentler slope on its left side (which appears brighter here) than on its right. Frequently, mountains shaped like this on Earth are fractured blocks of the planet's crust, thrusted upward and then tilted, creating a shallow slope on one side and a steeper slope on the fractured, faulted edge. Also presented here is an annotated version of the image, along with a radar image of the Dragoon Mountains in Arizona just east of Tucson. The Dragoon feature represents a tilted fault block, formed by spreading that has occurred across the western U.S., and has a similar shape to that of the Titan ridge. The Dragoon radar image was produced using data from NASA's Shuttle Radar Topography Mission (credit: NASA/JPL-Caltech/NGA). Radar illuminates the scene from the left in that image as well. Titan has displayed many features that are strikingly similar to Earth: lakes, seas, rivers, dunes and mountains. Scientists think it possible that, like Earth, the giant moon's crust has experienced familiar processes of uplift and spreading, followed by erosion. http://photojournal.jpl.nasa.gov/catalog/PIA20709

Other Targets in the Search for Life--from Saturn's Titan to Planetary Systems around other Stars

NASA Astrophysics Data System (ADS)

Lunine, J. I.

2001-12-01

In addition to the ``standard" targets in the search for life beyond Earth--namely Mars, Europa, and putative extra-solar terrestrial planets--there are others that are key to informing us as to the origin and persistence of life in the cosmos. Saturn's moon Titan, with its dense nitrogen atmosphere rich in methane, may hold important clues to how abiotic organic chemistry evolves toward biochemistry. In particular, while the stratospheric processing of methane and nitrogen by ultraviolet photons and cosmic rays generates a free radical chemistry that is by itself uninteresting from the point of view of biosynthesis, the products of this chemistry come to rest as liquids and solids on the surface of Titan. There, they are protected from upper atmospheric sources of energy, but localized surface processes, including those associated with impact heating, might drive the chemistry in interesting directions with respect to polymer structures, chirality, and other signatures of advanced organic chemistry. The first step in assessing these possibilities will come in three years with the Cassini-Huygens mission. Beyond our solar system, giant planets in orbit around other stars are not directly targets of the search for life elsewhere (their natural satellites being unpromising targets in terms of detectability), but their presence implies important things about the habitability of Earth-like planets that might orbit the same stars. Giant planets affect the orbital stability and impact history of terrestrial planets, as well as the delivery of water and biogenic compounds to the surfaces of putative ``other Earths". Further, giant planets provide fertile ground for testing detection and characterization techniques. Thus, to maximize the chances of success in answering the fundamental questions of astrobiology, we must broaden both our minds and the targets we choose to explore. Some of the work described herein was supported by the Jet Propulsion Laboratory's DDF, and by

The PROCESS experiment: amino and carboxylic acids under Mars-like surface UV radiation conditions in low-earth orbit.

PubMed

Noblet, Audrey; Stalport, Fabien; Guan, Yuan Yong; Poch, Olivier; Coll, Patrice; Szopa, Cyril; Cloix, Mégane; Macari, Frédérique; Raulin, Francois; Chaput, Didier; Cottin, Hervé

2012-05-01

The search for organic molecules at the surface of Mars is a top priority of the next Mars exploration space missions: Mars Science Laboratory (NASA) and ExoMars (ESA). The detection of organic matter could provide information about the presence of a prebiotic chemistry or even biological activity on this planet. Therefore, a key step in interpretation of future data collected by these missions is to understand the preservation of organic matter in the martian environment. Several laboratory experiments have been devoted to quantifying and qualifying the evolution of organic molecules under simulated environmental conditions of Mars. However, these laboratory simulations are limited, and one major constraint is the reproduction of the UV spectrum that reaches the surface of Mars. As part of the PROCESS experiment of the European EXPOSE-E mission on board the International Space Station, a study was performed on the photodegradation of organics under filtered extraterrestrial solar electromagnetic radiation that mimics Mars-like surface UV radiation conditions. Glycine, serine, phthalic acid, phthalic acid in the presence of a mineral phase, and mellitic acid were exposed to these conditions for 1.5 years, and their evolution was determined by Fourier transform infrared spectroscopy after their retrieval. The results were compared with data from laboratory experiments. A 1.5-year exposure to Mars-like surface UV radiation conditions in space resulted in complete degradation of the organic compounds. Half-lives between 50 and 150 h for martian surface conditions were calculated from both laboratory and low-Earth orbit experiments. The results highlight that none of those organics are stable under low-Earth orbit solar UV radiation conditions.

Aromatic, Alphatic, Enigmatic: The Chemistry of Titan

NASA Astrophysics Data System (ADS)

Horst, Sarah

2017-10-01

The extraordinary complexity of Titan’s atmospheric chemistry far surpasses that of any other solar system atmosphere. With its thick N2 atmosphere and stable bodies of liquid on its surface, Titan also possesses many physical processes that are similar to those that occur on Earth. The connection between Titan’s surface and atmosphere is unique in our solar system; atmospheric chemistry produces materials that are deposited on the surface and subsequently altered by surface-atmosphere interactions such as aeolian and fluvial processes resulting in the formation of extensive dune fields and expansive lakes and seas. Titan’s atmosphere is favorable for organic haze formation, which combined with the presence of some oxygen-bearing molecules indicates that Titan’s atmosphere may produce molecules of prebiotic interest. The combination of organics and liquid, in the form of water in a subsurface ocean and methane/ethane in the surface lakes and seas, means that Titan may be the ideal place in the solar system to test ideas about habitability, prebiotic chemistry, and the ubiquity and diversity of life in the universe. I will review our current understanding of chemistry on Titan forged from the powerful combination of Earth-based observations, remote sensing and in situ spacecraft measurements, laboratory experiments, and models. I will conclude with some of the questions that remain after Cassini-Huygens.

Ultramafic Terranes and Associated Springs as Analogs for Mars and Early Earth

NASA Technical Reports Server (NTRS)

Blake, David; Schulte, Mitch; Cullings, Ken; DeVincezi, D. (Technical Monitor)

2002-01-01

Putative extinct or extant Martian organisms, like their terrestrial counterparts, must adopt metabolic strategies based on the environments in which they live. In order for organisms to derive metabolic energy from the natural environment (Martian or terrestrial), a state of thermodynamic disequilibrium must exist. The most widespread environment of chemical disequilibrium on present-day Earth results from the interaction of mafic rocks of the ocean crust with liquid water. Such environments were even more pervasive and important on the Archean Earth due to increased geothermal heat flow and the absence of widespread continental crust formation. The composition of the lower crust and upper mantle of the Earth is essentially the-same as that of Mars, and the early histories of these two planets are similar. It follows that a knowledge of the mineralogy, water-rock chemistry and microbial ecology of Earth's oceanic crust could be of great value in devising a search strategy for evidence of past or present life on Mars. In some tectonic regimes, cross-sections of lower oceanic crust and upper mantle are exposed on land as so-called "ophiolite suites." Such is the case in the state of California (USA) as a result of its location adjacent to active plate margins. These mafic and ultramafic rocks contain numerous springs that offer an easily accessible field laboratory for studying water/rock interactions and the microbial communities that are supported by the resulting geochemical energy. A preliminary screen of Archaean biodiversity was conducted in a cold spring located in a presently serpentinizing ultramafic terrane. PCR and phylogenetic analysis of partial 16s rRNA, sequences were performed on water and sediment samples. Archaea of recent phylogenetic origin were detected with sequences nearly identical to those of organisms living in ultra-high pH lakes of Africa.

Titan's atmosphere (clouds and composition): new results

NASA Astrophysics Data System (ADS)

Griffith, C. A.

Titan's atmosphere potentially sports a cycle similar to the hydrologic one on Earth with clouds, rain and seas, but with methane playing the terrestrial role of water. Over the past ten years many independent efforts indicated no strong evidence for cloudiness until some unique spectra were analyzed in 1998 (Griffith et al.). These surprising observations displayed enhanced fluxes of 14-200 % on two nights at precisely the wavelengths (windows) that sense Titan's lower altitude where clouds might reside. The morphology of these enhancements in all 4 windows observed indicate that clouds covered ~6-9 % of Titan's surface and existed at ~15 km altitude. Here I discuss new observations recorded in 1999 aimed to further characterize Titan's clouds. While we find no evidence for a massive cloud system similar to the one observed previously, 1%-4% fluctuations in flux occur daily. These modulations, similar in wavelength and morphology to the more pronounced ones observed earlier, suggest the presence of clouds covering ≤1% of Titan's disk. The variations are too small to have been detected by most prior measurements. Repeated observations, spaced 30 minutes apart, indicate a temporal variability observable in the time scale of a couple of hours. The cloud heights hint that convection might govern their evolution. Their short lives point to the presence of rain.

Hints of Habitable Environments on Mars Challenge Our Studies of Mars-Analog Sites on Earth

NASA Technical Reports Server (NTRS)

desMarais, David J

2009-01-01

Life as we know it requires water with a chemical activity (alpha) >or approx.0.6 and sources of nutrients and useful energy. Some biota can survive even if favorable conditions occur only intermittently, but the minimum required frequency of occurrences is poorly understood. Recent discoveries have vindicated the Mars exploration strategy to follow the water. Mars Global Surveyor s Thermal Emission Spectrometer (TES) found coarse-grained hematite at Meridiani Planum. Opportunity rover confirmed this and also found evidence of ancient sulfate-rich playa lakes and near-surface groundwater. Elsewhere, TES found evidence of evaporitic halides in topographic depressions. But alpha might not have approached 0.6 in these evaporitic sulfate- and halide-bearing waters. Mars Express (MEX) and Mars Reconnaissance Orbiter (MRO) found extensive sulfate evaporites in Meridiani and Valles Marineris. MEX found phyllosilicates at several sites, most notably Mawrth Valles and Nili Fossae. MRO's CRISM near-IR mapper extended the known diversity and geographic distribution of phyllosilicates to include numerous Noachian craters. Phyllosilicates typically occur at the base of exposed ancient rock sections or in sediments in early Hesperian craters. It is uncertain whether the phyllosilicates developed in surface or subsurface aqueous environments and how long aqueous conditions persisted. Spirit rover found remarkably pure ferric sulfate, indicating oxidation and transport of Fe and S, perhaps in fumaroles or hot springs. Spirit also found opaline silica, consistent with hydrothermal activity. CRISM mapped extensive silica deposits in the Valles Marineris region, consistent with aqueous weathering and deposition. CRISM also found ultramafic rocks and magnesite at Nili Fossae, consistent with serpentinization, a process that can sustain habitable environments on Earth. The report of atmospheric methane implies subsurface aqueous conditions. A working hypothesis is that aqueous

Effects of topography on the dune forming winds on Titan

NASA Astrophysics Data System (ADS)

Larson, Erik J.; Toon, O. B.; Friedson, A. J.

2013-10-01

Cassini observed hundreds of dune fields on Titan, nearly all of which lie in the tropics and suggest westerly (from west to east) winds dominate at the surface. Most GCMs however have obtained easterly surface winds in the tropics, seemingly contradicting the wind direction suggested by the dunes. This has led to an active debate in the community about the origin of the dune forming winds on Titan and their direction and modality. This discussion is mostly driven by a study of Earth dunes seen as analogous to Titan. One can find examples of dunes on Earth that fit several wind regimes. To date only one GCM, that of Tokano (2008, 2010), has presented detailed analysis of its near surface winds and their dune forming capabilities. Despite the bulk of the wind being easterly, this GCM produces faster westerlies at equinox, thus transporting sand to the east. Our model, the Titan CAM (Friedson et al. 2009), is unable to reproduce the fast westerlies. Our GCM has been updated to include realistic topography released by the Cassini radar team. Preliminary results suggest our tropical wind regime now has net westerly winds in the tropics, albeit weak. References: Tokano, T. 2008. Icarus 194, 243-262. Tokano, T. 2010. Aeolian Research 2, 113-127. Friedson, J. et al. 2009. Planet. Sp. Sci., 57, 1931-1949.

Aerothermodynamic environments for Mars entry, Mars return, and lunar return aerobraking missions

NASA Astrophysics Data System (ADS)

Rochelle, W. C.; Bouslog, S. A.; Ting, P. C.; Curry, D. M.

1990-06-01

The aeroheating environments to vehicles undergoing Mars aerocapture, earth aerocapture from Mars, and earth aerocapture from the moon are presented. An engineering approach for the analysis of various types of vehicles and trajectories was taken, rather than performing a benchmark computation for a specific point at a selected time point in a trajectory. The radiation into Mars using the Mars Rover Sample Return (MRSR) 2-ft nose radius bionic remains a small contributor of heating for 6 to 10 km/sec; however, at 12 km/sec it becomes comparable with the convection. For earth aerocapture, returning from Mars, peak radiation for the MRSR SRC is only 25 percent of the peak convection for the 12-km/sec trajectory. However, when large vehicles are considered with this trajectory, peak radiation can become 2 to 4 times higher than the peak convection. For both Mars entry and return, a partially ablative Thermal Protection System (TPS) would be required, but for Lunar Transfer Vehicle return an all-reusable TPS can be used.

Atmospheric Models for Aerocapture

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta L.; Keller, Vernon W.

2004-01-01

There are eight destinations in the solar System with sufficient atmosphere for aerocapture to be a viable aeroassist option - Venus, Earth, Mars, Jupiter, Saturn and its moon Titan, Uranus, and Neptune. Engineering-level atmospheric models for four of these targets (Earth, Mars, Titan, and Neptune) have been developed for NASA to support systems analysis studies of potential future aerocapture missions. Development of a similar atmospheric model for Venus has recently commenced. An important capability of all of these models is their ability to simulate quasi-random density perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithm, and for thermal systems design. Similarities and differences among these atmospheric models are presented, with emphasis on the recently developed Neptune model and on planned characteristics of the Venus model. Example applications for aerocapture are also presented and illustrated. Recent updates to the Titan atmospheric model are discussed, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Probe entry at Titan.

Proceedings of the Astrobiology Science Conference 2010. Evolution and Life: Surviving Catastrophes and Extremes on Earth and Beyond

NASA Technical Reports Server (NTRS)

2010-01-01

Mars?; Titan Versus Europa - Potential for Astrobiology; Habitability Potential of Mars; Biosignatures: Tools and Development I; Origins of Molecular Asymmetry, Homochirality, and Life Detection; Deserts and Evaporite Basins and Associated Microbialite Systems; Ancient Life and Synthetic Biology: Crossroad of the Past and Future; Biosignatures: Tools and Development II; Free Oxygen: Proxies, Causes, and Consequences; Life in Modern Microbialite Systems - Function and Adaptation; Hydrothermal Systems and Organosynthesis Processes: Origin and Evolution of Life; Where Should We Go on Mars to Seek Signs of Life?; Search for Intelligent Life I. Innovative SETI Observing Programs and Future Directions; Integrating Astrobiology Research Across and Beyond the Community; Education in Astrobiology in K-12; Search for Intelligent Life II. Global Engagement and Interstellar Message Construction; Poster sessions included: Extraterrestrial Molecular Evolution and Pre-Biological Chemistry; Prebiotic Evolution: From Chemistry to Life; RNA World; Terrestrial Evolution: Implications for the Past, Present, and Future of Life on Earth; Hydrothermal Systems and Organosynthesis Processes: Origin and Evolution of Life; Virology and Astrobiology; Horizontal Genetic Transfer and Properties of Ancestral Organisms; Life in Volcanic Environments: On Earth and Beyond; Impact Events and Evolution; Evolution of Advanced Life; Evolution of Intelligent Life; Education in Astrobiology in K-12; Origins of Molecular Asymmetry, Homochirality, and Life Detection; Astrobiology and Interdisciplinary Communication; Diversity in Astrobiology Research and Education; Integrating Astrobiology Research Across and Beyond the Community; Policy and Societal Issues: Dealing with Potential Bumps in the Astrobiology Road Ahead; Results from ASTEP and Other Astrobiology Field Campaigns; Energy Flow in Microbial Ecosystems; Psychrophiles and Polar Environments; Deserts and Evaporite Basins and Associated Microbialite

Multi-wavelength search for complex molecules in Titan's Atmosphere

NASA Astrophysics Data System (ADS)

Nixon, C. A.; Cordiner, M. A.; Greathouse, T. K.; Richter, M.; Kisiel, Z.; Irwin, P. G.; Teanby, N. A.; Kuan, Y. J.; Charnley, S. B.

2017-12-01

Titan's atmosphere is one of the most complex astrochemical environments known: the photochemistry of methane and nitrogen, induced by solar UV and Saturn magnetospheric electron impacts, creates a bonanza of organic molecules like no other place in the solar system. Cassini has unveiled the first glimpses of Titan's chemical wonderland, but many gaps remain. In particular, interpreting the mass spectra of Titan's upper atmosphere requires external knowledge, to disentangle the signature of molecules from their identical-mass brethren. Cassini infrared spectroscopy with CIRS has helped to some extent, but is also limited by low spectral resolution. Potentially to the rescue, comes high-resolution spectroscopy from the Earth at infrared and sub-millimeter wavelengths, where molecules exhibit vibrational and rotational transitions respectively. In this presentation, we describe the quest to make new, unique identifications of large molecules in Titan's atmosphere, focusing specifically on cyclic molecules including N-heterocycles. This molecular family is of high astrobiological significance, forming the basic ring structure for DNA nucleobases. We present the latest spectroscopic observations of Titan from ALMA and NASA's IRTF telescope, discussing present findings and directions for future work.

Large catchment area recharges Titan's Ontario Lacus

NASA Astrophysics Data System (ADS)

Dhingra, Rajani D.; Barnes, Jason W.; Yanites, Brian J.; Kirk, Randolph L.

2018-01-01

We seek to address the question of what processes are at work to fill Ontario Lacus while other, deeper south polar basins remain empty. Our hydrological analysis indicates that Ontario Lacus has a catchment area spanning 5.5% of Titan's surface and a large catchment area to lake surface area ratio. This large catchment area translates into large volumes of liquid making their way to Ontario Lacus after rainfall. The areal extent of the catchment extends to at least southern mid-latitudes (40°S). Mass conservation calculations indicate that runoff alone might completely fill Ontario Lacus within less than half a Titan year (1 Titan year = 29.5 Earth years) assuming no infiltration. Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations of clouds over the southern mid and high-latitudes are consistent with precipitation feeding Ontario's large catchment area. This far-flung rain may be keeping Ontario Lacus filled, making it a liquid hydrocarbon oasis in the relatively dry south polar region.

Near-Earth and near-Mars asteroids: Prognosis of pyroxene types

NASA Technical Reports Server (NTRS)

Shestopalov, D. I.; Golubeva, L. F.

1991-01-01

The diagnostic signs of ferrous absorption band at 505nm and color index (u-x) found at main-belt asteroids and 6-parametric classification of light stone meteorites have been the basis of the work. The colorimetric data of light near-Earth and near-Mars asteroids from TRIAD and ECAS were analyzed. Composition fields of pyroxenes were obtained for these asteroids by the value of (u-x) and 505-nm ferrous absorption band position within the pyroxenes quadrilateral. Pyroxenes of the S-asteroids from Apollo-Amor which have spectral parameters similar to achondrites may be presented by the diopside series.

The organic aerosols of Titan

NASA Technical Reports Server (NTRS)

Khare, B. N.; Sagan, C.; Thompson, W. R.; Arakawa, E. T.; Suits, F.; Calcott, T. A.; Williams, M. W.; Shrader, S.; Ogino, H.; Willingham, T. O.

1986-01-01

A dark reddish organic solid, called tholin, is synthesized from simulated Titanian atmospheres by irradiation with high energy electrons in a plasma discharge. The visible reflection spectrum of this tholin is found to be similar to that of high altitude aerosols responsible for the albedo and reddish color of Titan. The real (n) and imaginary (k) parts of the complex refractive index of thin films of Titan prepared by continuous dc discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mb is determined from X-ray to microwave frequencies. Values of n (approx. 1.65) and k (approx. 0.004 to 0.08) in the visible are consistent with deductions made by groundbased and spaceborne observations of Titan. Many infrared absorption features are present in k(lambda), including the 4.6 micrometer nitrile band. Molecular analysis of the volatile components of this tholin was performed by sequential and nonsequential pyrolytic gas chromatography/mass spectrometry. More than one hundred organic compounds are released; tentative identifications include saturated and unsaturated aliphatic hydrocarbons, substituted polycylic aromatics, nitriles, amines, pyrroles, pyrazines, pyridines, pyrimidines, and the purine, adenine. In addition,acid hydrolysis produces a racemic mixture of biological and nonbiological amino acids. Many of these molecules are implicated in the origin of life on Earth, suggesting Titan as a contemporary laboratory environment for prebiological organic chemistry on a planetary scale.

Launch window analysis in a new perspective with examples of departures from Earth to Mars

NASA Technical Reports Server (NTRS)

Thibodeau, J. R., III; Bond, V. R.

1972-01-01

Earth-departure windows are investigated for two round trip stopover missions to Mars. These are the 1981 inbound Venus swingby mission and the 1986 direct minimum-energy mission. The secular effects of planetary oblateness are used to predict the motion of the parking orbit. A procedure is developed for matching the motion of the parking orbit and the escape asymptote. Earth-departure velocity penalties, caused by orbital plane misalinement, are reduced by synchronizing the motion of the parking orbit and the escape trajectory.

Determining Possible Building Blocks of the Earth and Mars

NASA Technical Reports Server (NTRS)

Burbine, T. H.; OBrien, K. M.

2004-01-01

One of the fundamental questions concerning planetary formation is exactly what material did the planets form from? All the planets in our solar system are believed to have formed out of material from the solar nebula. Chondritic meteorites appear to sample this primitive material. Chondritic meteorites are generally classified into 13 major groups, which have a variety of compositions. Detailed studies of possible building blocks of the terrestrial planets require samples that can be used to estimate the bulk chemistry of these bodies. This study will focus on trying to determine possible building blocks of Earth and Mars since samples of these two planets can be studied in detail in the laboratory.

Probing Small Lakes on Titan Using the Cassini RADAR Altimeter

NASA Astrophysics Data System (ADS)

Mastrogiuseppe, M.; Poggiali, V.; Hayes, A.; Lunine, J. I.; Seu, R.; Lorenz, R. D.; Mitri, G.; Mitchell, K. L.; Janssen, M. A.; Casarano, D.; Notarnicola, C.; Le Gall, A. A.

2017-12-01

The T126 Cassini's final flyby of Titan has offered a unique opportunity to observe an area in the Northern Polar terrain, where several small - medium size (10 - 50 km) hydrocarbon lakes are present and have been previously imaged by Cassini. The successful observation allowed the radar to operate at the closest approach over several small lakes, using its altimetry mode for the investigation of depth and liquid composition. Herein we present the result of a dedicate processing previously applied to altimetric data acquired over Ligeia Mare where the radar revealed the bathymetry and composition of the sea [1,2]. We show that, the optimal geometry condition met during the T126 fly-by allowed the radar to probe Titan's lakes revealing that such small liquid bodies can exceed one-hundred meters of depth. [1] M. Mastrogiuseppe et al. (2014, Mar.). The bathymetry of a Titan Sea. Geophysical Research Letters. [Online]. 41 (5), pp. 1432-1437. Available: http://dx.doi.org/10.1002/2013GL058618 [2] M.Mastrogiuseppe et al. (2016, Oct). Radar Sounding Using the Cassini Altimeter: Waveform Modeling and Monte Carlo Approach for Data Inversion of Observations of Titan's Seas, IEEE Transactions On Geoscience And Remote Sensing, Vol. 54, No. 10, doi: 10.1109/TGRS.2016.2563426.

Volcanism on Mars

NASA Astrophysics Data System (ADS)

Head, J. W.

1981-11-01

Characterization of volcanic activity on Mars is reviewed and comparisons are made with knowledge of terrestrial volcanic history. The high frequency of calderas on earth and low abundance on Mars is taken to indicate a lack of plate tectonic subduction zones and silicic volcanism on Mars. Further characterization is noted to depend on remote sensing from Viking orbital and earth-based spectral and albedo data. Theoretical models of causative mechanisms of terrestrial morphology will be used to establish models of similar processes on Mars, including deposits identification, eruptive conditions, and theories of magma ascent, as well as the role of volatiles from both deep and shallow sources. The importance of returning to Mars with appropriately instrumented spacecraft to test the new theories is stressed. The topics were discussed in papers presented at the Mars colloquium at the California Institute of Technology in August, 1981.

Roles of Clathrate Hydrates in Crustal Heating and Volatile Storage/Release on Earth, Mars, and Beyond

NASA Astrophysics Data System (ADS)

Kargel, J. S.; Beget, J.; Furfaro, R.; Prieto-Ballesteros, O.; Palmero-Rodriguez, J. A.

2007-12-01

Clathrate hydrates are stable through much of the Solar System. These materials and hydrate-like amorphous associations of water with N2, CO, CH4, CO2, O2 and other molecules could, in fact, constitute the bulk of the non-rock components of some icy satellites, comets, and Kuiper Belt Objects. CO2 clathrate is thermodynamically stable at the Martian South Pole surface and could form a significant fraction of both Martian polar caps and icy permafrost distributed across one-third of the Martian surface. CH4 clathrate is the largest clathrate material in Earth's permafrost and cold seafloor regions, and it may be a major volatile reservoir on Mars, too. CO2 clathrate is less abundant on Earth but it might store most of Mars' CO2 inventory and thus may be one of the critical components in the climate system of that planet, just as CH4 clathrate is for Earth. These ice-like phases not only store biologically, geologically, and climatologically important gases, but they also are natural thermal insulators. Thus, they retard the conductive flow of geothermal heat, and thick accumulations of them can modify geotherms, cause brines to exist where otherwise they would not, and induce low-grade metamorphism of upper crustal rocks underlying the insulating bodies. This mechanism of crustal heating may be especially important in assisting hydrogeologic activity on Mars, gas-rich carbonaceous asteroids, icy satellites, and Kuiper Belt Objects. These worlds, compared to Earth, are comparatively energy starved and frozen but may partly make up for their deficit of joules by having large accumulations of joule-conserving hydrates. Thick, continuous layers of clathrate may seal in gases and produce high gas fugacities in aquifers underlying the clathrates, thus producing gas-rich reservoirs capable of erupting violently. This may have happened repeatedly in Earth history, with global climatic consequences for abrupt climate change. We have hypothesized that such eruptions may have

The Cassini/Huygens Doppler Wind Experiment: Results from the Titan Descent

NASA Technical Reports Server (NTRS)

Bird, M. K.; Dutta-Roy, R.; Allison, M.; Asmar, S. W.; Atkinson, D. H.; Edenhofer, P.; Plettemeier, D.; Tyler, G. L.

2005-01-01

The primary objective of the Doppler Wind Experiment (DWE), one of the six scientific investigations comprising the payload of the ESA Huygens Probe, is a determination of the wind velocity in Titan's atmosphere. Measurements of the Doppler shift of the S-band (2040 MHz) carrier signal to the Cassini Orbiter and to Earth were recorded during the Probe descent in order to deduce wind-induced motion of the Probe to an accuracy better than 1 m s-1. An experiment with the same scientific goal was performed with the Galileo Probe at Jupiter. Analogous to the Galileo experience, it was anticipated that the frequency of the Huygens radio signal could be measured on Earth to obtain an additional component of the horizontal winds. Specific secondary science objectives of DWE include measurements of: (a) Doppler fluctuations to determine the turbulence spectrum and possible wave activity in the Titan atmosphere; (b) Doppler and signal level modulation to monitor Probe descent dynamics (e.g., spinrate/spinphase, parachute swing); (c) Probe coordinates and orientation during descent and after impact on Titan.

Terrestrial analogs to Mars

NASA Technical Reports Server (NTRS)

Farr, T. G.; Arcone, S.; Arvidson, R.; Baker, V.; Barlow, N.; Beaty, D.; Bell, M.; Blankenship, D.; Bridges, N.; Briggs, G.;

A probabilistic framework for single-station location of seismicity on Earth and Mars

NASA Astrophysics Data System (ADS)

Böse, M.; Clinton, J. F.; Ceylan, S.; Euchner, F.; van Driel, M.; Khan, A.; Giardini, D.; Lognonné, P.; Banerdt, W. B.

2017-01-01

Locating the source of seismic energy from a single three-component seismic station is associated with large uncertainties, originating from challenges in identifying seismic phases, as well as inevitable pick and model uncertainties. The challenge is even higher for planets such as Mars, where interior structure is a priori largely unknown. In this study, we address the single-station location problem by developing a probabilistic framework that combines location estimates from multiple algorithms to estimate the probability density function (PDF) for epicentral distance, back azimuth, and origin time. Each algorithm uses independent and complementary information in the seismic signals. Together, the algorithms allow locating seismicity ranging from local to teleseismic quakes. Distances and origin times of large regional and teleseismic events (M > 5.5) are estimated from observed and theoretical body- and multi-orbit surface-wave travel times. The latter are picked from the maxima in the waveform envelopes in various frequency bands. For smaller events at local and regional distances, only first arrival picks of body waves are used, possibly in combination with fundamental Rayleigh R1 waveform maxima where detectable; depth phases, such as pP or PmP, help constrain source depth and improve distance estimates. Back azimuth is determined from the polarization of the Rayleigh- and/or P-wave phases. When seismic signals are good enough for multiple approaches to be used, estimates from the various methods are combined through the product of their PDFs, resulting in an improved event location and reduced uncertainty range estimate compared to the results obtained from each algorithm independently. To verify our approach, we use both earthquake recordings from existing Earth stations and synthetic Martian seismograms. The Mars synthetics are generated with a full-waveform scheme (AxiSEM) using spherically-symmetric seismic velocity, density and attenuation models of

Radiative Transfer Simulations of Earth Spectra as Registered by ROSETTA/VIRTIS

NASA Astrophysics Data System (ADS)

Hurley, Jane; Irwin, P.; Adriani, A.; Moriconi, M.; Oliva, F.; Coradini, A.

2010-10-01

Rosetta, part of ESA's Horizon 2000 programme, will orbit and land on the comet 67P/Churyumov-Gerasimenko in May 2014. However, launched in March 2004, its trajectory has thus far muchly consisted of a series of planetary fly-bys and gravitational assists using Mars (2007) and Earth (March 2005, 2007 and 2009). During these close fly-bys Rosetta captured measurements of these planets - and of particular interest are those registed by the Visual Infrared Thermal Imaging Spectrometer VIRTIS of Earth, which were taken to help calibrate VIRTIS. Rosetta/VIRTIS measures at high spectral resolution from 0.25 - 5.0 microns, a spectral range which has been well studied by Earth observing instruments such as Meteosat Second Generation Spinning Enhanced Visible and Infrared Imager (MSG/SEVIRI) and the Advanced Along-Track Scanning Radiometer (AATSR). Earth observing instruments, whilst having superior spatio-temporal coverage to the data provided during the Rosetta/VIRTIS fly-bys, are typically constrained to measuring in only a few spectral channels. Hence, Rosetta/VIRTIS should yield more detailed spectral information than these instruments - and is a good candidate for intercomparison studies. To this end, the radiative transfer software NEMESIS (Irwin et al., 2009) is employed for the first time on Earth simulations, having been used extensively for other bodies such as Venus, Mars, Jupiter, Saturn, Neptune, Uranus and Titan. This work compares Rosetta/VIRTIS measurements with NEMESIS-simulated spectra, concentrating on quantifying the ability of NEMESIS to reproduce spectral features associated with different surface topographies (such as ocean, desert and vegetation) in combination with clear and cloudy atmospheric states. Preliminary estimations of temperature and trace-species concentrations and distributions are presented as sample products.

Weathering profiles in soils and rocks on Earth and Mars

NASA Astrophysics Data System (ADS)

Hausrath, E.; Adcock, C. T.; Bamisile, T.; Baumeister, J. L.; Gainey, S.; Ralston, S. J.; Steiner, M.; Tu, V.

2017-12-01

Interactions of liquid water with rock, soil, or sediments can result in significant chemical and mineralogical changes with depth. These changes can include transformation from one phase to another as well as translocation, addition, and loss of material. The resulting chemical and mineralogical depth profiles can record characteristics of the interacting liquid water such as pH, temperature, duration, and abundance. We use a combined field, laboratory, and modeling approach to interpret the environmental conditions preserved in soils and rocks. We study depth profiles in terrestrial field environments; perform dissolution experiments of primary and secondary phases important in soil environments; and perform numerical modeling to quantitatively interpret weathering environments. In our field studies we have measured time-integrated basaltic mineral dissolution rates, and interpreted the impact of pH and temperature on weathering in basaltic and serpentine-containing rocks and soils. These results help us interpret fundamental processes occurring in soils on Earth and on Mars, and can also be used to inform numerical modeling and laboratory experiments. Our laboratory experiments provide fundamental kinetic data to interpret processes occurring in soils. We have measured dissolution rates of Mars-relevant phosphate minerals, clay minerals, and amorphous phases, as well as dissolution rates under specific Mars-relevant conditions such as in concentrated brines. Finally, reactive transport modeling allows a quantitative interpretation of the kinetic, thermodynamic, and transport processes occurring in soil environments. Such modeling allows the testing of conditions under longer time frames and under different conditions than might be possible under either terrestrial field or laboratory conditions. We have used modeling to examine the weathering of basalt, olivine, carbonate, phosphate, and clay minerals, and placed constraints on the duration, pH, and solution

Orographic forcing of dune forming winds on Titan

NASA Astrophysics Data System (ADS)

Larson, E. J.; Toon, O. B.; Friedson, A. J.

2013-12-01

Cassini has observed hundreds of dune fields on Titan, nearly all of which lie in the tropics and suggest westerly (from west to east) winds dominate at the surface [1,2]. Most GCMs however have obtained easterly surface winds in the tropics, seemingly contradicting the wind direction suggested by the dunes. This has led to an active debate in the community about the origin of the dune forming winds on Titan and their direction and modality. This discussion is mostly driven by a study of Earth dunes seen as analogous to Titan [1,2,3]. One can find examples of dunes on Earth that fit several wind regimes. To date only one GCM, that of Tokano [4,5], has presented detailed analysis of its near surface winds and their dune forming capabilities. Despite the bulk of the wind being easterly, this GCM produces faster westerlies at equinox, thus transporting sand to the east. Our model, the Titan CAM [6], is unable to reproduce the fast westerlies, although it is possible we are not outputting frequently enough to catch them. Our GCM has been updated to include realistic topography released by the Cassini radar team. Preliminary results suggest our tropical wind regime now has net westerly winds in the tropics, albeit weak. References: [1], Lorenz, R. et al. 2006. Science, 312, 724-727. [2], Radebaugh, J. et al. 2008. Icarus, 194, 690-703. [3] Rubin, D. and Hesp, P. 2009. Nature Geoscience 2, 653-658. [4] Tokano, T. 2008. Icarus 194, 243-262. [5] Tokano, T. 2010. Aeolian Research 2, 113-127. [6] Friedson, J. et al. 2009. Planetary Space Science, 57, 1931-1949.

Titan Submarine: Exploring The Depths of Kraken Mare

NASA Technical Reports Server (NTRS)

Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

2015-01-01

The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase I for 2014. The effort investigated what science a submarine for Titan's liquid hydrocarbon approximately 93 Kelvin (-180 degrees Centigrade) seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (approximately100 kilograms) it was found that a submersible platform can accomplish extensive and exciting science both above and below the surface of the Kraken Mare The submerged science includes mapping using side looking sonar, imaging and spectroscopy of the sea at all depths, as well as sampling of the sea's bottom and shallow shoreline. While surfaced the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 kilometers inland. This imaging requirement pushed the landing date to Titan's next summer period (approximately 2047) to allow for continuous lighted conditions, as well as direct-to-Earth (DTE) communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid/sediment/chemical interactions. An estimated 25 megabits of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system. This paper discusses the results of Phase I as well as the plans for Phase II.

The limits of life on Earth and searching for life on Mars

NASA Technical Reports Server (NTRS)

Nealson, K. H.

1997-01-01

Considerations of basic properties of bacteria such as size, structure, and metabolic versatility allow one to understand how these remarkable life-forms are so adaptable to environments previously thought to be uninhabitable. It is now appreciated that bacteria on Earth can utilize almost any redox couple that yields energy, taking advantage of this energy, while transforming the elements during metabolism. The ability to grow at the expense of inorganic redox couples allows the microbes to occupy niches not available to the more metabolically constrained eukaryotes. Furthermore, the simplicity of the bacterial structure allows them considerably more resistance to environmental variables (pH, salinity, temperature) that are toxic or lethal to more complex organisms. This information can be used to explain the predominance of prokaryotes in extreme environments on Earth, and to speculate as to simple types of metabolism and biogeochemical cycles that may exist on this planet, Mars, and perhaps other non-Earth environments.

The limits of life on Earth and searching for life on Mars.

PubMed

Nealson, K H

1997-10-25

Considerations of basic properties of bacteria such as size, structure, and metabolic versatility allow one to understand how these remarkable life-forms are so adaptable to environments previously thought to be uninhabitable. It is now appreciated that bacteria on Earth can utilize almost any redox couple that yields energy, taking advantage of this energy, while transforming the elements during metabolism. The ability to grow at the expense of inorganic redox couples allows the microbes to occupy niches not available to the more metabolically constrained eukaryotes. Furthermore, the simplicity of the bacterial structure allows them considerably more resistance to environmental variables (pH, salinity, temperature) that are toxic or lethal to more complex organisms. This information can be used to explain the predominance of prokaryotes in extreme environments on Earth, and to speculate as to simple types of metabolism and biogeochemical cycles that may exist on this planet, Mars, and perhaps other non-Earth environments.

Titan's missing ethane: From the atmosphere to the subsurface

NASA Astrophysics Data System (ADS)

Gilliam, Ashley E.; Lerman, Abraham

2016-09-01

The second most abundant component of the present-day Titan atmosphere, methane (CH4), is known to undergo photolytic conversion to ethane (C2H6) that accumulates as a liquid on Titan's surface. Condensation temperature of ethane is higher than that of methane, so that ethane "rain" may be expected to occur before the liquefaction of methane. At present, the partial pressure of ethane in the atmosphere is 1E-5 bar, much lower than 1E-1 bar of CH4. Estimated 8.46E17 kg or 1.37E6 km3 of C2H6 have been produced on Titan since accretion. The Titan surface reservoirs of ethane are lakes and craters, of estimated volume of 50,000 km3 and 61,000 km3, respectively. As these are smaller than the total volume of liquid ethane produced in the course of Titan's history, the excess may be stored in the subsurface of the crust, made primarily of water ice. The minimum porosity of the crust needed to accommodate all the liquid ethane would be only 0.9% of the uppermost 2 km of the crust. The occurrence of CH4 and liquid C2H6 on Titan has led to much speculation on the possibility of life on that satellite. The aggregation of organic molecules in a "primordial soup or bullion" depends in part on the viscosity of the medium, diffusivity of organic molecules in it, and rates of polymerization reactions. The temperatures on Titan, much lower than on primordial Earth, are less favorable to the "Second Coming of life" on Titan.

Effects of the seasonal cycle on superrotation in planetary atmospheres

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

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

2014-05-20

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

Direct Measurements of Surface Energy, Elastic Modulus and Interparticle Forces of Titan Aerosol Analog (`Tholin') Using Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Yu, X.; Horst, S. M.; He, C.; McGuiggan, P.; Bridges, N. T.

2017-12-01

To understand the origin of the dunes on Titan, it is important to investigate the material properties of the sand particles on Titan, which are mainly made of organics deposited from the atmosphere [1]. The organic sand may behave differently compared to the quartz/basaltic sand on terrestrial planets (Earth, Venus, Mars) in terms of interparticle forces. We measured the surface energy (through contact angle measurements) and elastic modulus (through Atomic Force Microscopy, AFM) of Titan aerosol analog (tholins) produced in our lab. Tholins may be compositionally similar to sand on Titan. We directly measured the interparticle forces between a tholin particle adhered to an AFM cantilver and tholin particles on a substrate. We also measured the properties of walnut shells, a typical material used in the Titan Wind Tunnel (TWT, [2, 3]). We find the surface energy of a tholin thin film is about 70.9 mN/m and its elastic modulus is about 3.5 GPa (similar to hard polymers like PMMA and polystyrene). We used the two measured material properties of tholin to calculate its interparticle cohesion assuming simple sphere-sphere geometry [4]. For two 20 µm particles, the theoretical cohesion force is about 6682 nN. Under dry nitrogen (RH<1%), the directly measured interparticle forces using AFM was approximately 4000 nN, which is smaller than theoretical predictions but still relatively strong under dry conditions. The interparticle cohesion between walnut shell particles is only 200 nN, which is much lower than between tholin particles. The key finding of this study is that the interparticle cohesion forces are much larger for tholins and presumably Titan sand particles than for terrestrial sand and materials used in the wind tunnel. This suggests we should increase the interparticle force in both analog experiments (TWT) and threshold models (e.g. [5]) to correctly translate the results to real Titan conditions. The strong cohesion of tholins may also inform us how the

On developing thermal cave detection techniques for earth, the moon and mars

USGS Publications Warehouse

Wynne, J. Judson; Titus, Timothy N.; Chong Diaz, Guillermo

2008-01-01

The purpose of this study is to (1) demonstrate the viability of detecting terrestrial caves at thermal-infrared wavelengths, (2) improve our understanding of terrestrial cave thermal behavior, (3) identify times of day when cave openings have the maximum thermal contrast with the surrounding surface regolith, and (4) further our understanding of how to detect caves on Earth, the Moon and Mars. We monitored the thermal behavior of two caves in the Atacama Desert of northern Chile. Through this work, we identified times when temperature contrasts between entrance and surface were greatest, thus enabling us to suggest optimal overflight times. The largest thermal contrast for both caves occurred during mid-day. One cave demonstrated thermal behavior at the entrance suggestive of cold-trapping, while the second cave demonstrated temperature shifts suggestive of airflow. We also collected thermograms without knowing optimal detection times; these images suggest both caves may also be detectable during off-peak times. We suggest cave detection using thermal remote sensing on Earth and other planetary objects will be limited by (1) capturing imagery in the appropriate thermal wavelength, (2) the size of cave entrance vs. the sensor's spatial resolution, (3) the viewing angle of the platform in relation to the slope trajectory of the cave entrance, (4) the strength of the thermal signal associated with the cave entrance, and (5) the time of day and season of thermal image capture. Through this and other studies, we will begin to identify the range of conditions under which caves are detectable in the thermal infrared and thus improve our detection capabilities of these features on Earth, the Moon and Mars. ?? 2008 Elsevier B.V.

Insights on landscape evolution and climatic forcing on Titan

NASA Astrophysics Data System (ADS)

Lucas, A.; Daudon, C.; Rodriguez, S.; Cornet, T.; Perron, J. T.

2017-12-01

The landscapes of Titan were observed for nearly 13 years by the Cassini spacecraft and Huygens probe. With dunes, mountains, seas, lakes, rivers..., the great morphological variety observed testifies to the geological richness that Titan shares with the Earth. In this study, we combine analysis of radar and hyperspectral data provided by the Cassini-Huygens mission, with models of valley and river network evolution to better understand the processes at work that sculpt these familiar landscapes. We develop quantitative criteria for comparing 3D morphologies obtained by numerical simulation with those derived for Titan by photogrammetry. These criteria are validated on Earth's landscapes. We simulate morphologies similar to those observed and show that landscapes at the equator and poles are mainly controlled by river incision and mass wasting such as landslides for which we quantify their respective contribution. Subsequently, we relate modeling to precipitation rates of methane and show values that are to be compared with general circulation model predictions (GCM). Our results also show a very young age of formation of the observed morphologies, less than a few million years. Finally, we provide new constraints on current amplitude of the tidal effects and organic precipitation rates from atmosphere chemistry.

Evidence for Seismogenic Hydrogen Gas, a Potential Microbial Energy Source on Earth and Mars.

PubMed

McMahon, Sean; Parnell, John; Blamey, Nigel J F

2016-09-01

The oxidation of molecular hydrogen (H2) is thought to be a major source of metabolic energy for life in the deep subsurface on Earth, and it could likewise support any extant biosphere on Mars, where stable habitable environments are probably limited to the subsurface. Faulting and fracturing may stimulate the supply of H2 from several sources. We report the H2 content of fluids present in terrestrial rocks formed by brittle fracturing on fault planes (pseudotachylites and cataclasites), along with protolith control samples. The fluids are dominated by water and include H2 at abundances sufficient to support hydrogenotrophic microorganisms, with strong H2 enrichments in the pseudotachylites compared to the controls. Weaker and less consistent H2 enrichments are observed in the cataclasites, which represent less intense seismic friction than the pseudotachylites. The enrichments agree quantitatively with previous experimental measurements of frictionally driven H2 formation during rock fracturing. We find that conservative estimates of current martian global seismicity predict episodic H2 generation by Marsquakes in quantities useful to hydrogenotrophs over a range of scales and recurrence times. On both Earth and Mars, secondary release of H2 may also accompany the breakdown of ancient fault rocks, which are particularly abundant in the pervasively fractured martian crust. This study strengthens the case for the astrobiological investigation of ancient martian fracture systems. Deep biosphere-Faults-Fault rocks-Seismic activity-Hydrogen-Mars. Astrobiology 16, 690-702.

Proposal to Simultaneously Profile Wind and CO2 on Earth and Mars With 2-micron Pulsed Lidar Technologies

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Koch, Grady J.; Kavaya, Michael J.; Amzajerdian, Farzin; Ismail, Syed; Emmitt, David

2005-01-01

2-micron lidar technology has been in use and under continued improvement for many years toward wind measurements. But the 2-micron wavelength region is also rich in absorption lines of CO2 (and H2O to a lesser extent) that can be exploited with the differential absorption lidar (DIAL) technique to make species concentration measurements. A coherent detection receiver offers the possibility of making combined wind and DIAL measurements with wind derived from frequency shift of the backscatter spectrum and species concentration derived from power of the backscatter spectrum. A combined wind and CO2 measurement capability is of interest for applications on both Earth and Mars. CO2 measurements in the Earth atmosphere are of importance to studies of the global carbon cycle. Data on vertically-resolved CO2 profiles over large geographical observations areas are of particular interest that could potentially be made by deploying a lidar on an aircraft or satellite. By combining CO2 concentration with wind measurements an even more useful data product could be obtained in the calculation of CO2 flux. A challenge to lidar in this application is that CO2 concentration measurements must be made with a high level of precision and accuracy to better than 1%. The Martian atmosphere also presents wind and CO2 measurement problems that could be met with a combined DIAL/Doppler lidar. CO2 concentration in this scenario would be used to calculate atmospheric density since the Martian atmosphere is composed of 95% CO2. The lack of measurements of Mars atmospheric density in the 30-60 km range, dust storm formation and movements, and horizontal wind patterns in the 0-20 km range pose significant risks to aerocapture, and entry, descent, and landing of future robotic and human Mars missions. Systematic measurement of the Mars atmospheric density and winds will be required over several Mars years, supplemented with day-of-entry operational measurements. To date, there have been 5

An overview of the descent and landing of the Huygens probe on Titan.

PubMed

Lebreton, Jean-Pierre; Witasse, Olivier; Sollazzo, Claudio; Blancquaert, Thierry; Couzin, Patrice; Schipper, Anne-Marie; Jones, Jeremy B; Matson, Dennis L; Gurvits, Leonid I; Atkinson, David H; Kazeminejad, Bobby; Pérez-Ayúcar, Miguel

2005-12-08

Titan, Saturn's largest moon, is the only Solar System planetary body other than Earth with a thick nitrogen atmosphere. The Voyager spacecraft confirmed that methane was the second-most abundant atmospheric constituent in Titan's atmosphere, and revealed a rich organic chemistry, but its cameras could not see through the thick organic haze. After a seven-year interplanetary journey on board the Cassini orbiter, the Huygens probe was released on 25 December 2004. It reached the upper layer of Titan's atmosphere on 14 January and landed softly after a parachute descent of almost 2.5 hours. Here we report an overview of the Huygens mission, which enabled studies of the atmosphere and surface, including in situ sampling of the organic chemistry, and revealed an Earth-like landscape. The probe descended over the boundary between a bright icy terrain eroded by fluvial activity--probably due to methane-and a darker area that looked like a river- or lake-bed. Post-landing images showed centimetre-sized surface details.

Aeolian Landscapes of Titan from Cassini RADAR Reveal Winds, Elevation Constraints and Sediment Characteristics

NASA Astrophysics Data System (ADS)

Radebaugh, J.; Lewis, R. C.; Bishop, B.; Christiansen, E. H.; Kerber, L.; Rodriguez, S.; Narteau, C.; Le Gall, A. A.; Lucas, A.; Malaska, M.

2017-12-01

Similar to terrestrial bodies with atmospheres, a significant portion of the surface of Titan is covered in aeolian landscapes, now imaged by Cassini RADAR at close to 50% coverage. While the compositions of the wind-carried and wind-carved sediments are under discussion, their characteristics, such as being rounded, loose and capable of being saltated, or being fine, soft and forming easily erodible deposits, can be discerned from the geomorphology. Large duneforms are similar to those in Earth's big deserts, formed by particles in strict size and shape limits, and steep, badlands-like morphologies of yardang regions indicate soft rocks with armored features. Shapes and orientations of dunes and yardangs can also reveal wind directions and effects of elevation and topographic obstacles. Recent studies of dunes in the Belet Sand Sea of Titan's equatorial trailing hemisphere reveal dunes are generally wider and with greater spacing near the center, similar to dunes in the Namib Sand Sea of Earth. Dune-to-interdune ratios decrease toward higher latitudes, as was previously observed, and are slightly higher in regions of low elevation, which may relate to elevation affecting winds and sand transport capacity. However, this relationship is not as strong for the Namib. Furthermore, the effects of the location of dunes with respect to sand sea margins on dune parameter values has only begun to be explored. The European ERA-Interim (observations plus model) wind results for the Namib reveal vector sum winds are several degrees away from down the dune long axis, consistent with the fingering mode of dune growth, and allowing for down-axis sand transport. We assume similar model winds for the dunes of Titan. Model winds for the yardangs of the Lut desert of Earth are directly down axis, which means wind directions should be able to be determined in the isolated yardang fields of Titan's northern midlatitudes. Further studies of dune parameters on Titan from Cassini can help

Transient Climate Effects of Large Impacts on Titan

NASA Technical Reports Server (NTRS)

Zahnle, Kevin J.; Korycansky, Donald; Nixon, Conor A.

2013-01-01

Titan's thick atmosphere and volatile-rich surface cause it to respond to big impacts in a somewhat Earth-like manner. Here we construct a simple globally-averaged model that tracks the flow of energy through the environment in the weeks, years, and millenia after a big comet strikes Titan. The model Titan is endowed with 1.4 bars of N2 and 0.07 bars of CH4, methane lakes, a water ice crust, and enough methane underground to saturate the regolith to the surface. We find that a nominal Menrva impact is big enough to raise the surface temperature by approx. 80 K and to double the amount of methane in the atmosphere. The extra methane drizzles out of the atmosphere over hundreds of years. An upper-limit Menrva is just big enough to raise the surface to water's melting point. The putative Hotei impact (a possible 800-1200 km diameter basin, Soderblom et al., 2009) is big enough to raise the surface temperature to 350-400 K. Water rain must fall and global meltwaters might range between 50 m to more than a kilometer deep, depending on the details. Global meltwater oceans do not last more than a few decades or centuries at most, but are interesting to consider given Titan's organic wealth. Significant near-surface clathrate formation is possible as Titan cools but faces major kinetic barriers.

Advanced Radioisotope Power System Enabled Titan Rover Concept with Inflatable Wheels

NASA Astrophysics Data System (ADS)

Balint, Tibor S.; Schriener, Timothy M.; Shirley, James H.

2006-01-01

The Decadal Survey identified Titan as one of the top priority science destinations in the large moons category, while NASA's proposed Design Reference Mission Set ranked a Titan in-situ explorer second, after a recommended Europa Geophysical Explorer mission. This paper discusses a Titan rover concept, enabled by a single advanced Radioisotope Power System that could provide about 110 We (BOL). The concept targets the smaller Flagship or potentially the New Frontiers mission class. This MSL class rover would traverse on four 1.5 m diameter inflatable wheels during its 3 years mission duration and would use as much design and flight heritage as possible to reduce mission cost. Direct to Earth communication would remove the need for a relay orbiter. Details on the strawman instrument payload, and rover subsystems are given for this science driven mission concept. In addition, power system trades between Advanced RTG, TPV, and Advanced-Stirling and Brayton RPSs are outlined. While many possible approaches exist for Titan in-situ exploration, the Titan rover concept presented here could provide a scientifically interesting and programmatically affordable solution.

Titan aerosol and gas experiment for the Huygens Probe

NASA Technical Reports Server (NTRS)

Carle, G. C.; Kojiro, D. R.; Oberbeck, V.; Ohara, B. J.; Pollack, J. B.; Valentin, J. R.; Bar-Nun, A.; Cohen, M. J.; Ferris, J. P.; Greenberg, J. M.

1991-01-01

The Cassini Mission is a joint undertaking of NASA and the European Space Agency (ESA) to explore the Saturnian System with a Saturn Orbiter and a Titan Probe. The launch vehicle and the Saturn Orbiter are the responsibility of NASA while the Huygens Probe (detachable Titan Probe) is the responsibility of ESA. The spacecraft will be launched in 1996 and the Huygens Probe will arrive at Titan in 2003. The Cassini Mission-Huygens Probe provides a unique opportunity to obtain detailed information about the atmosphere and, possibly, the surface of Titan. Titan possesses a substantial nitrogen atmosphere containing methane and many other organic compounds. Aerosols play an important role in the atmospheric processes on Titan. The Huygens Probe offers an opportunity to determine how organic particles are formed and grow which will clarify their role on Earth. A powerful analytical instrument, capable of addressing the above technology and other science questions, was recently proposed for the Huygens Probe. It is comprised of an aerosol and gas sampler and processor, and a gas chromatograph-ion mobility spectrometer. The instrument will be able to measure complex organics that make up the collected aerosols to the approximate 1 ppm level. Gases will be measured to approximately 10 ppb. Because the Titan atmosphere is expected to be quite complex, a gas chromatograph-ion mobility spectrometer is used to provide unequivocal identification of the components of the analytes. Further details of the science question to be investigated and the proposed instrument are described. The expected results and their implications are also addressed.

The Nitrate/(Per)Chlorate Relationship on Mars

NASA Technical Reports Server (NTRS)

Stern, Jennifer C.; Sutter, Brad; Jackson, W. Andrew; Navarro-Gonzalez, Rafael; McKay, Christopher P.; Ming, Douglas W.; Archer, P. Douglas; Mahaffy, Paul R.

2017-01-01

Nitrate was recently detected in Gale Crater sediments on Mars at abundances up to approximately 600 mg/kg, confirming predictions of its presence at abundances consistent with models based on impact-generated nitrate and other sources of fixed nitrogen. Terrestrial Mars analogs, Mars meteorites, and other solar system materials help establish a context for interpreting in situ nitrate measurements on Mars, particularly in relation to other cooccuring salts. We compare the relative abundance of nitrates to oxychlorine (chlorate and/or perchlorate, hereafter (per)chlorate) salts on Mars and Earth. The nitrate/(per)chlorate ratio on Mars is greater than 1, significantly lower than on Earth (nitrate/(per)chlorate greater than 10(exp.3)), suggesting not only the absence of biological activity but also different (per)chlorate formation mechanisms on Mars than on Earth.

Explosive Volcanic Eruptions from Linear Vents on Earth, Venus and Mars: Comparisons with Circular Vent Eruptions

NASA Technical Reports Server (NTRS)

Glaze, Lori S.; Baloga, Stephen M.; Wimert, Jesse

2010-01-01

Conditions required to support buoyant convective plumes are investigated for explosive volcanic eruptions from circular and linear vents on Earth, Venus, and Mars. Vent geometry (linear versus circular) plays a significant role in the ability of an explosive eruption to sustain a buoyant plume. On Earth, linear and circular vent eruptions are both capable of driving buoyant plumes to equivalent maximum rise heights, however, linear vent plumes are more sensitive to vent size. For analogous mass eruption rates, linear vent plumes surpass circular vent plumes in entrainment efficiency approximately when L(sub o) > 3r(sub o) owing to the larger entrainment area relative to the control volume. Relative to circular vents, linear vents on Venus favor column collapse and the formation of pyroclastic flows because the range of conditions required to establish and sustain buoyancy is narrow. When buoyancy can be sustained, however, maximum plume heights exceed those from circular vents. For current atmospheric conditions on Mars, linear vent eruptions are capable of injecting volcanic material slightly higher than analogous circular vent eruptions. However, both geometries are more likely to produce pyroclastic fountains, as opposed to convective plumes, owing to the low density atmosphere. Due to the atmospheric density profile and water content on Earth, explosive eruptions enjoy favorable conditions for producing sustained buoyant columns, while pyroclastic flows would be relatively more prevalent on Venus and Mars. These results have implications for the injection and dispersal of particulates into the planetary atmosphere and the ability to interpret the geologic record of planetary volcanism.

From Earth to Mars, Radiation Intensities in Interplanetary Space

NASA Astrophysics Data System (ADS)

O'Brien, Keran

2007-10-01

The radiation field in interplanetary space between Earth and Mars is rather intense. Using a modified version of the ATROPOS Monte Carlo code combined with a modified version of the deterministic code, PLOTINUS, the effective dose rate to crew members in space craft hull shielded with a shell of 2 g/cm^2 of aluminum and 20 g/cm^2 of polyethylene was calculated to be 51 rem/y. The total dose during the solar-particle event of September 29, 1989, GLE 42, was calculated to be 50 rem. The dose in a ``storm cellar'' of 100 g/cm^2 of polyethylene equivalent during this time was calculated to be 5 rem. The calculations were for conditions corresponding to a recent solar minimum.

Choosing Mars-Time: Analysis of the Mars Exploration Rover Experience

NASA Technical Reports Server (NTRS)

Bass, Deborah S.; Wales,Roxana C.; Shalin, Valerie L.

2004-01-01

This paper focuses on the Mars Exploration Rover (MER) mission decision to work on Mars Time and the implications of that decision on the tactical surface operations process as personnel planned activities and created a new command load for work on each Martian sol. The paper also looks at tools that supported the complexities of Mars Time work, and makes some comparisons between Earth and Mars time scheduling.

Origin and Evolution of Nitrogen on Titan, Enceladus, Triton, and Pluto

NASA Technical Reports Server (NTRS)

Atreya, S. K.; Niemann, H. B.; Mahaffy, P. R.; Owen, T. C.

2007-01-01

Nitrogen, together with carbon, hydrogen, oxygen, phosphorus and sulfur (CHNOPS), plays a central role in life as we know it. Indeed, molecular nitrogen is the most abundant component of the terrestrial atmosphere, and second only to carbon dioxide on Mars and Venus. The Voyager and Cassini-Huygens observations show that copious nitrogen is present on Titan also, comprising some 95% by volume of this moon's 1500 millibar atmosphere. After water vapor, it may be the most abundant (4%) of the gases around tiny Enceladus, as revealed by the recent Cassini observations. A thin nitrogen atmosphere is found even on the coldest of the solar system bodies, Triton and Pluto. The available evidence on nitrogen isotopes and the heavy noble gases suggests that Titan acquired its nitrogen largely in the form of ammonia. Subsequent chemical evolution, beginning with the photolysis of NH3 on primordial Titan, led to the nitrogen atmosphere we see on Titan today. This is also the scenario for the origin of nitrogen on the terrestrial planets. Contrary to Titan, the colder outer solar system objects, Triton and Pluto, neither had the luxury of receiving much arnmonia in the first place, nor of photolyzing whatever little ammonia they did receive in the planetesimals that formed them. On the other hand, it is plausible the planetesimals were capable of trapping and delivering molecular nitrogen directly to Triton and Pluto, unlike Titan. The origin of nitrogen on Enceladus is somewhat enigmatic. A scenario similar to Titan's, but with a role for the interior processes, may be at work. In this paper, we will discuss the source and loss of nitrogen for the above objects, and why Ganymede, the largest moon in the solar system, is nitrogen starved.

Tectonics and volcanism on Mars: a compared remote sensing analysis with earthly geostructures

NASA Astrophysics Data System (ADS)

Baggio, Paolo; Ancona, M. A.; Callegari, I.; Pinori, S.; Vercellone, S.

1999-12-01

The recent knowledge on Mars' lithosphere evolution does not find yet sufficient analogies with the Earth's tectonic models. The Viking image analysis seems to be even now frequently, rather fragmentary, and do not permits to express any coherent relationships among the different detected phenomena. Therefore, today it is impossible to support any reliable kinematic hypothesis. The Remote-Sensing interpretation is addressed to a Viking image mosaic of the known Tharsis Montes region and particularly focused on the Arsia Mons volcano. Several previously unknown lineaments, not directly linked to volcano-tectonics, were detected. Their mutual relationships recall transcurrent kinematics that could be related to similar geostructural models known in the Earth plate tectonic dynamics. Several concordant relationships between the Arsia Mons volcano and the brittle extensive tectonic features of earthly Etnean district (Sicily, South Italy), interpreted on Landsat TM images, were pointed out. These analogies coupled with the recently confirmed strato- volcano topology of Tharsis Montes (Head and Wilson), the layout distribution of the effusive centers (Arsia, Pavonis and Ascraeus Montes), the new tectonic lineaments and the morphological features, suggest the hypothesis of a plate tectonic volcanic region. The frame could be an example in agreement with the most recent interpretation of Mars (Sleep). A buried circular body, previously incorrectly interpreted as a great landslide event from the western slope of Arsia Mons volcano, seems really to be a more ancient volcanic structure (Arsia Mons Senilis), which location is in evident relation with the interpreted new transcurrent tectonic system.

Overview of our current understanding of the Titan ionosphere

NASA Astrophysics Data System (ADS)

Cravens, Thomas

An ionosphere was first detected on Titan in 1980 by the Voyager 1 radio occultation experi-ment and the first in situ measurements were made in 2004 by the Cassini spacecraft, although many theoretical studies were carried out prior to the Cassini mission. Earth and Titan are similar in that molecular nitrogen is the major neutral atmospheric species but these bodies differ in that the next most abundant species at Earth is molecular oxygen and at Titan is methane. As a consequence, the chemistry in the upper atmosphere and ionosphere is quite different for the two bodies. Titan's upper atmosphere and ionosphere strongly interact with Saturn's magnetospheric plasma. Magnetic fields were observed in Titan's ionosphere by the Cassini magnetometer and are induced as a consequence of this interaction, which affects the flow and distribution of plasma. Energetic electrons and ions from Saturn's magnetosphere precipitate into the upper atmosphere, acting as both heat and ionization sources. However, on the dayside, absorption of solar extreme ultraviolet radiation is thought to be the dominant source of ionization and energy. The electron temperatures measured in the ionosphere by the Cassini Langmuir probe (RPWS/LP) are about 1000 K, greatly exceeding the neutral temper-ature (about 150 K). The ion and neutral mass spectrometer (INMS) onboard Cassini detected a large number of ion species with mass numbers up to 100 Daltons and the energetic plasma spectrometer (CAPS) detected both negative and positive ion species at even higher mass num-bers. Primary ionization processes create N2+, N+, CH4+, CH3+, and other ion species, but a complex ion-neutral chemistry, involving methane and other hydrocarbon and nitriles species (acetylene, ethylene, ethane, hydrogen cyanide, benzene,. . . .), convert these initial species into numerous other species including CH5+, C2H5+, HCNH+, C3H5+, CH2NH2+, C6H7+. As in most ionospheres, chemistry dominates the ionospheric structure at

ESAS-Derived Earth Departure Stage Design for Human Mars Exploration

NASA Technical Reports Server (NTRS)

Flaherty, Kevin; Grant, Michael; Korzun, Ashley; Malo-Molina, Faure; Steinfeldt, Bradley; Stahl, Benjamin; Wilhite, Alan

2007-01-01

The Vision for Space Exploration has set the nation on a course to have humans on Mars as early as 2030. To reduce the cost and risk associated with human Mars exploration, NASA is planning for the Mars architecture to leverage the lunar architecture as fully as possible. This study takes the defined launch vehicles and system capabilities from ESAS and extends their application to DRM 3.0 to design an Earth Departure Stage suitable for the cargo and crew missions to Mars. The impact of a propellant depot in LEO was assessed and sLzed for use with the EDS. To quantitatively assess and compare the effectiveness of alternative designs, an initial baseline architecture was defined using the ESAS launch vehicles and DRM 3.0. The baseline architecture uses three NTR engines, LH2 propellant, no propellant depot in LEO, and launches on the Ares I and Ares V. The Mars transfer and surface elements from DRM 3.0 were considered to be fixed payloads in the design of the EDS. Feasible architecture alternatives were identified from previous architecture studies and anticipated capabilities and compiled in a morphological matrix. ESAS FOMs were used to determine the most critical design attributes for the effectiveness of the EDS. The ESAS-derived FOMs used in this study to assess alternative designs are effectiveness and performance, affordability, reliability, and risk. The individual FOMs were prioritized using the AHP, a method for pairwise comparison. All trades performed were evaluated with respect to the weighted FOMs, creating a Pareto frontier of equivalently ideal solutions. Additionally, each design on the frontier was evaluated based on its fulfillment of the weighted FOMs using TOPSIS, a quantitative method for ordinal ranking of the alternatives. The designs were assessed in an integrated environment using physics-based models for subsystem analysis where possible. However, for certain attributes such as engine type, historical, performance-based mass estimating

Miniature Cryogenic Valves for a Titan Lake Sampling System

NASA Technical Reports Server (NTRS)

Sherrit, Stewart; Zimmerman, Wayne; Takano, Nobuyuki; Avellar, Louisa

2014-01-01

The Cassini mission has revealed Titan to be one of the most Earthlike worlds in the Solar System complete with many of the same surface features including lakes, river channels, basins, and dunes. But unlike Earth, the materials and fluids on Titan are composed of cryogenic organic compounds with lakes of liquid methane and ethane. One of the potential mission concepts to explore Titan is to land a floating platform on one of the Titan Lakes and determine the local lake chemistry. In order to accomplish this within the expected mass volume and power budgets there is a need to pursue the development for a low power lightweight cryogenic valves which can be used along with vacuum lines to sample lake liquid and to distribute to various instruments aboard the Lander. To meet this need we have initiated the development of low power cryogenic valves and actuators based on a single crystal piezoelectric flextensional stacks produced by TRS Ceramics Inc. Since the origin of such high electromechanical properties of Relaxor-PT single crystals is due to the polarization rotation effect, (i.e., intrinsic contributions), the strain per volt decrease at cryogenic temperatures is much lower than in standard Lead Zirconate Titanate (PZT) ceramics. This makes them promising candidates for cryogenic actuators with regards to the stroke for a given voltage. This paper will present our Titan Lake Sampling and Sample Handling system design and the development of small cryogenic piezoelectric valves developed to meet the system specifications.

The Mars Sample Return Project

NASA Technical Reports Server (NTRS)

O'Neil, W. J.; Cazaux, C.

2000-01-01

The Mars Sample Return (MSR) Project is underway. A 2003 mission to be launched on a Delta III Class vehicle and a 2005 mission launched on an Ariane 5 will culminate in carefully selected Mars samples arriving on Earth in 2008. NASA is the lead agency and will provide the Mars landed elements, namely, landers, rovers, and Mars ascent vehicles (MAVs). The French Space Agency CNES is the largest international partner and will provide for the joint NASA/CNES 2005 Mission the Ariane 5 launch and the Earth Return Mars Orbiter that will capture the sample canisters from the Mars parking orbits the MAVs place them in. The sample canisters will be returned to Earth aboard the CNES Orbiter in the Earth Entry Vehicles provided by NASA. Other national space agencies are also expected to participate in substantial roles. Italy is planning to provide a drill that will operate from the Landers to provide subsurface samples. Other experiments in addition to the MSR payload will also be carried on the Landers. This paper will present the current status of the design of the MSR missions and flight articles. c 2000 American Institute of Aeronautics and Astronautics, Inc. Published by Elsevier Science Ltd.

Titan Lifting Entry & Atmospheric Flight (T-LEAF) Science Mission

NASA Astrophysics Data System (ADS)

Lee, G.; Sen, B.; Ross, F.; Sokol, D.

2016-12-01

Northrop Grumman has been developing the Titan Lifting Entry & Atmospheric Flight (T-LEAF) sky rover to roam the lower atmosphere and observe at close quarters the lakes and plains of Saturn's ocean moon, Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in-situ instruments to the surface of Titan. T-LEAF is a highly maneuverable sky rover and its aerodynamic shape (i.e., a flying wing) does not restrict it to following prevailing wind patterns on Titan, but allows mission operators to chart its course. This freedom of mobility allows T-LEAF to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations. We will present a straw man concept of T-LEAF, including size, mass, power, on-board science payloads and measurement, and surface science dropsonde deployment CONOPS. We will discuss the various science instruments and their vehicle level impacts, such as meteorological and electric field sensors, acoustic sensors for measuring shallow depths, multi-spectral imagers, high definition cameras and surface science dropsondes. The stability of T-LEAF and its long residence time on Titan will provide for time to perform a large aerial survey of select prime surface targets deployment of dropsondes at selected locations surface measurements that are coordinated with on-board remote measurements communication relay capabilities to orbiter (or Earth). In this context, we will specifically focus upon key factors impacting the design and performance of T-LEAF science: science payload accommodation, constraints and opportunities characteristics of flight, payload deployment and measurement CONOPS in the Titan atmosphere. This presentation will show how these factors provide constraints as well as enable opportunities for novel long duration scientific studies of Titan's surface.

Solubility of oxygen in liquid Fe at high pressure and consequences for the early differentiation of Earth and Mars

NASA Astrophysics Data System (ADS)

Rubie, D. C.; Gessmann, C. K.; Frost, D. J.

2003-04-01

Knowledge of the solubility of oxygen in liquid iron enables the partitioning of oxygen between metal and silicates and the oxidation state of residual silicates to be constrained during core formation in planetary bodies. We have determined oxygen solubility experimentally at 5--23 GPa, 2100--2700 K and oxygen fugacities 1--4 log units below the iron-wüstite buffer in samples of liquid Ni-Fe alloy contained in magnesiowüstite capsules using a multianvil apparatus. Results show that oxygen solubility increases with increasing temperature but decreases slightly with increasing pressure over the range of experimental conditions, at constant oxygen fugacity. Using an extrapolation of the results to higher pressures and temperatures, we have modeled the geochemical consequences of metal-silicate separation in magma oceans in order to explain the contrasting FeO contents of the mantles of Earth and Mars. We assume that both Earth and Mars accreted originally from material with a chondritic composition; because the initial oxidation state is uncertain, we vary this parameter by defining the initial oxygen content. Two metal-silicate fractionation models are considered: (1) Metal and silicate are allowed to equilibrate at fictive conditions that approximate the pressure and temperature at the base of a magma ocean. (2) The effect of settling Fe droplets in a magma ocean is determined using a simple polybaric metal-silicate fractionation model. We assume that the temperature at the base of a magma ocean is close to the peridotite liquidus. In the case of Earth, high temperatures in a magma ocean with a depth >1200 km would have resulted in significant quantities of oxygen dissolving in the liquid metal with the consequent extraction of FeO from the residual silicate. In contrast, on Mars, even if the magma ocean extended to the depth of the current core-mantle boundary, temperatures would not have been sufficiently high for oxygen solubility in liquid metal to be

Electrification of organic particles explains apparent absence of small-scale bedforms on Titan

NASA Astrophysics Data System (ADS)

Pähtz, T.; Duran Vinent, O.

2017-12-01

Harper et al. (Nat. Geosci., 2017) recently reported measurements that contact electrification tends to charge Titan sand, which is mainly composed of low-density organic particles, much more readily than Earth sand. We here show that this finding has major implications for the formation of bedforms on Titan by incorporating it into a recent unified theory of sediment transport cessation across environments (https://arxiv.org/abs/1602.07079): The modified theory predicts that the cessation threshold and thus the saturation length of sediment transport on Titan increase strongly as a result of contact electrification. We then use the predicted saturation length as an input in a recent unified bedform model by Duran and co-workers to explain the apparent absence of small-scale bedforms on Titan suggested by observations.

Dunes on Saturn’s moon Titan as revealed by the Cassini Mission

NASA Astrophysics Data System (ADS)

Radebaugh, Jani

2013-12-01

Dunes on Titan, a dominant landform comprising at least 15% of the surface, represent the end product of many physical processes acting in alien conditions. Winds in a nitrogen-rich atmosphere with Earth-like pressure transport sand that is likely to have been derived from complex organics produced in the atmosphere. These sands then accumulate into large, planet-encircling sand seas concentrated near the equator. Dunes on Titan are predominantly linear and similar in size and form to the large linear dunes of the Namib, Arabian and Saharan sand seas. They likely formed from wide bimodal winds and appear to undergo average sand transport to the east. Their singular form across the satellite indicates Titan’s dunes may be highly mature, and may reside in a condition of stability that permitted their growth and evolution over long time scales. The dunes are among the youngest surface features, as even river channels do not cut through them. However, reorganization time scales of large linear dunes on Titan are likely tens of thousands of years. Thus, Titan’s dune forms may be long-lived and yet be actively undergoing sand transport. This work is a summary of research on dunes on Titan after the Cassini Prime and Equinox Missions (2004-2010) and now during the Solstice Mission (to end in 2017). It discusses results of Cassini data analysis and modeling of conditions on Titan and it draws comparisons with observations and models of linear dune formation and evolution on Earth.

GEMINI-TITAN (GT)-3 - EARTH-SKY VIEWS - CA

NASA Image and Video Library

1965-03-23

S65-18741 (23 March 1965) --- Astronaut John W. Young took this picture during the Gemini-Titan 3 three-orbit mission as the spacecraft "Molly Brown" passed over Northern Mexico. The large light-brown area is the Sonoran Desert. The Colorado River runs from upper right to lower left. The lower portion of the picture is Mexico, the upper left is California, and the upper right is Arizona. The altitude of the spacecraft was 90 miles. Young used a hand-held modified 70mm Hasselblad camera with color film. The lens setting was 250th of a second at f/11.

LiDAR observations of an Earth magmatic plumbing system as an analog for Venus and Mars distributed volcanism

NASA Astrophysics Data System (ADS)

Richardson, Jacob; Connor, Charles; Malservisi, Rocco; Bleacher, Jacob; Connor, Laura

2014-05-01

Clusters of tens to thousands of small volcanoes (diameters generally <30 km) are common features on the surface of Mars, Venus, and the Earth. These clusters may be described as distributed-style volcanism. Better characterizing the magmatic plumbing system of these clusters can constrain magma ascent processes as well as the regional magma production budget and heat flux beneath each cluster. Unfortunately, directly observing the plumbing systems of volcano clusters on Mars and Venus eludes our current geologic abilities. Because erosion exposes such systems at the Earth's surface, a better understanding of magmatic processes and migration can be achieved via field analysis. The terrestrial plumbing system of an eroded volcanic field may be a valuable planetary analog for Venus and Mars clusters. The magmatic plumbing system of a Pliocene-aged monogenetic volcanic field, emplaced at 0.8 km depth, is currently exposed as a sill and dike swarm in the San Rafael Desert of Central Utah, USA. The mafic bodies in this region intruded into Mesozoic sedimentary units and now make up the most erosion resistant units as sills, dikes, and plug-like conduits. Light Detection and Ranging (LiDAR) can identify volcanic units (sills, dikes, and conduits) at high resolution, both geomorphologically and with near infrared return intensity values. Two Terrestrial LiDAR Surveys and an Airborne LiDAR Survey have been carried out over the San Rafael volcanic swarm, producing a three dimensional point cloud over approximately 36 sq. km. From the point clouds of these surveys, 1-meter DEMs are produced and volcanic intrusions have been mapped. Here we present reconstructions of the volcanic instrusions of the San Rafael Swarm. We create this reconstruction by extrapolating mapped intrustions from the LiDAR surveys into a 3D space around the current surface. We compare the estimated intrusive volume to the estimated conduit density and estimates of extrusive volume at volcano clusters of

'Mars-shine'

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] 'Mars-shine' Composite

NASA's Mars Exploration Rover Spirit continues to take advantage of favorable solar power conditions to conduct occasional nighttime astronomical observations from the summit region of 'Husband Hill.'

Spirit has been observing the martian moons Phobos and Deimos to learn more about their orbits and surface properties. This has included observing eclipses. On Earth, a solar eclipse occurs when the Moon's orbit takes it exactly between the Sun and Earth, casting parts of Earth into shadow. A lunar eclipse occurs when the Earth is exactly between the Sun and the Moon, casting the Moon into shadow and often giving it a ghostly orange-reddish color. This color is created by sunlight reflected through Earth's atmosphere into the shadowed region. The primary difference between terrestrial and martian eclipses is that Mars' moons are too small to completely block the Sun from view during solar eclipses.

Recently, Spirit observed a 'lunar' eclipse on Mars. Phobos, the larger of the two martian moons, was photographed while slipping into the shadow of Mars. Jim Bell, the astronomer in charge of the rover's panoramic camera (Pancam), suggested calling it a 'Phobal' eclipse rather than a lunar eclipse as a way of identifying which of the dozens of moons in our solar system was being cast into shadow.

With the help of the Jet Propulsion Laboratory's navigation team, the Pancam team planned instructions to Spirit for acquiring the views shown here of Phobos as it entered into a lunar eclipse on the evening of the rover's 639th martian day, or sol (Oct. 20, 2005) on Mars. This image is a time-lapse composite of eight Pancam images of Phobos moving across the martian sky. The entire eclipse lasted more than 26 minutes, but Spirit was able to observe only in the first 15 minutes. During the time closest to the shadow crossing, Spirit's cameras were programmed to take images every 10

The Astrobiology of the Subsurface: Caves and Rock Fracture Habitats on Earth, Mars and Beyond

NASA Technical Reports Server (NTRS)

Boston, Penelope J.

2017-01-01

The Astrobiology of the Subsurface: Exploring Cave Habitats on Earth, Mars and Beyond. We are using the spectacular underground landscapes of Earth caves as models for the subsurfaces of other planets. Caves have been detected on the Moon and Mars and are strongly suspected for other bodies in the Solar System including some of the ice covered Ocean Worlds that orbit gas giant planets. The caves we explore and study include many extreme conditions of relevance to planetary astrobiology exploration including high and low temperatures, gas atmospheres poisonous to humans but where exotic microbes can fluorish, highly acidic or salty fluids, heavy metals, and high background radiation levels. Some cave microorganisms eat their way through bedrock, some live in battery acid conditions, some produce unusual biominerals and rare cave formations, and many produce compounds of potential pharmaceutical and industrial significance. We study these unique lifeforms and the physical and chemical biosignatures that they leave behind. Such traces can be used to provide a Field Guide to Unknown Organisms for developing life detection space missions.

Fluid dynamics of liquids on Titans surface

NASA Astrophysics Data System (ADS)

Ori, Gian Gabriele; Marinangeli, Lucia; Baliva, Antonio; Bressan, Mario; Strom, Robert G.

1998-10-01

On the surface of Titan liquids can be present in three types of environments : (i) oceans, (ii) seas and lakes, and (iii) fluvial channels. The liquid in these environments will be affected by several types of motion: progressive (tidal) waves, wind-generated waves and unidirectional currents. The physical parameters of the liquid on Titans surface can be reconstructed using the Peng-Robinson equation of state. The total energy of the waves, both tidal and wind, depends on the gravity and liquid density ; both values are lower on Titan than on Earth. Thus, the same total energy will produce larger waves on Titan. This is also valid also for the progressive waves, as it is confirmed by the physical relationship between horizontal velocity, wave amplitude, and depth of the liquid. Wind-driven waves also will tend to be larger, because the viscosity of the liquid (which is lower on Titan) controls the deformation of the liquid under shear stress. Wind-generated waves would be rather large, but the dimension of the liquid basin limits the size of the waves ; in small lakes or seas the wave power cannot reach large values. Unidirectional currents are also affected by the liquid properties. Both the relations from driving and resting forces and the Reynolds number suggests that the flows exhibit a large erosional capacity and that, theoretically, a true fluvial network could be formed. However, caution should be exercised, because the cohesion of the sedimentary interface can armour bottom and induce laterally extensive, unchanelled sheet flows with small erosional capacity.

Ground Based Monitoring of Cloud Activity on Titan

NASA Astrophysics Data System (ADS)

Corlies, Paul; Hayes, Alexander; Rojo, Patricio; Ádámkovics, Máté; Turtle, Elizabeth; Buratti, Bonnie

2014-11-01

We will report on the latest results of an on-going ground based monitoring campaign of Saturn’s moon Titan using the SINFONI (Spectrograph for INtegral Field Observations in the Near Infrared) instrument on the Very Large Telescope (VLT). Presently, much is still unknown about the complex and dynamic hydrologic system of Titan as observations have yet to be made through an entire Titan year (29.7 Earth years). Because of the limited ability to observe Titan with Cassini, a combined ground and spaced-based approach provides a steady cadence of observation throughout the duration of a Titan year. We will present the results of observations to date using the adaptive optics (AO) mode (weather dependent) of SINFONI. We have been regularly observing Titan since April 2014 for the purpose of monitoring and identifying clouds and have also been in collaboration with the Cassini team that has concurrent ISS observations and historical VIMS observations of clouds. Our discussion will focus on the various algorithms and approaches used for cloud identification and analysis. Currently, we are entering into a very interesting time for clouds and Titan hydrology as Saturn moves into north polar summer for the first time since Cassini entered the Saturnian system. The increased insolation that this will bring to the north, where the majority of the liquid methane lakes reside, will give us our first observations of the potentially complex interplay between surface liquid and atmospheric conditions. By carefully monitoring and characterizing clouds (size, optical depth, altitude, etc.) we will also be able to derive constraints that can help to guide and validate GCMs. Since the beginning of our observations, no clouds have been observed through ground based observations, while Cassini has only observed a single cloud event in the north polar region over Ligeia Mare. We will provide an update on the latest results of our cloud monitoring campaign and discuss how this

Titan and Triton: two large satellites with fine tectonic granulation

NASA Astrophysics Data System (ADS)

Kochemasov, G.

There is a strict relationship between orbital frequencies and tectonic granulations of celestial bodies: higher frequency - finer granules, lower frequency ,larger granules. These wave induced granules are a consequence of an interference of standing waves of 4 directions occurring in rotating celestial bodies due to their movements in non- round (elliptical, parabolic) orbits with periodically changing accelerations. These changing accelerations arouse in bodies warping inertia-gravity waves having a stationary character. A direct viewing of them now is possible due to excellent "Cassini SC" images of saturnian satellites. Ubiquity of these wave induced granules allowed to formulate the 3rd theorem of the wave planetary tectonics [1]: "Celestial bodies are granular". At first, this law was illustrated by a row of terrestrial planets starting from Sun: Solar photosphere orbiting the center of the solar system has the granule size πR/60, Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1. This granulation in Sun is known long ago as famous solar supergranulation with the characteristic size ˜30 000 km. At Earth it was observed with help of geological and deeper geophysical data as eight superstructures about 5000 km in diameter in a great planetary circle. But now one can observe them directly due to a "lucky" image of Earth from a distance 1 170 000 km (Image PIA04159 taken by MRO). Four large granules of Mars make its figure elongated ellipsoidal what was known long enough but not explained. Two waves long πR inscribed in the great circle must produce this oblong figure. One wave long 2πR in the great circle makes all asteroids oblong and convexo-concave. "Orbits make structures"- but satellites have two orbits in our solar system. This only means that to 2 main waves and corresponding to them granules one has to add 2 side waves and corresponding to them granules. The side waves are modulated (calculated) by division and multiplication of

Mars Human Exploration Objectives

NASA Technical Reports Server (NTRS)

Briggs, Geoff

1998-01-01

This paper reviews the objectives and other considerations of Human exploration of Mars. The objectives of human exploration of Mars are: (1) to learn how Mars is similar to, and different from, Earth; (2) to explore possible life, past and present; (3) to discover what Mars is like now from the perspective of Geoscience and geologic history; and (4) how did Mars form and how did its formation differ from Earth. Considerations of human Martian exploration involve: (1) having a capable base laboratory; (2) having long range transportation; (3) having operational autonomy of the crew, and the requirement of the crew to possess a range of new cognitive processes along with easy communications with terrestrial colleagues; and finally (4) creating the human habitat along with human factors which involve more than just survivability.

Planetary Perspective on Life on Early Mars and the Early Earth

NASA Technical Reports Server (NTRS)

Sleep, Norman H.; Zahnle, Kevin

1996-01-01

Impacts of asteroids and comets posed a major hazard to the continuous existence of early life on Mars as on the Earth. The chief danger was presented by globally distributed ejecta, which for very large impacts takes the form of transient thick rock vapor atmospheres; both planets suffered such impacts repeatedly. The exposed surface on both planets was sterilized when it was quickly heated to the temperature of condensed rock vapor by radiation and rock rain. Shallow water bodies were quickly evaporated and sterilized. Any surviving life must have been either in deep water or well below the surface.

The divergent fates of primitive hydrospheric water on Earth and Mars.

PubMed

Wade, Jon; Dyck, Brendan; Palin, Richard M; Moore, James D P; Smye, Andrew J

2017-12-20

Despite active transport into Earth's mantle, water has been present on our planet's surface for most of geological time. Yet water disappeared from the Martian surface soon after its formation. Although some of the water on Mars was lost to space via photolysis following the collapse of the planet's magnetic field, the widespread serpentinization of Martian crust suggests that metamorphic hydration reactions played a critical part in the sequestration of the crust. Here we quantify the relative volumes of water that could be removed from each planet's surface via the burial and metamorphism of hydrated mafic crusts, and calculate mineral transition-induced bulk-density changes at conditions of elevated pressure and temperature for each. The metamorphic mineral assemblages in relatively FeO-rich Martian lavas can hold about 25 per cent more structurally bound water than those in metamorphosed terrestrial basalts, and can retain it at greater depths within Mars. Our calculations suggest that in excess of 9 per cent by volume of the Martian mantle may contain hydrous mineral species as a consequence of surface reactions, compared to about 4 per cent by volume of Earth's mantle. Furthermore, neither primitive nor evolved hydrated Martian crust show noticeably different bulk densities compared to their anhydrous equivalents, in contrast to hydrous mafic terrestrial crust, which transforms to denser eclogite upon dehydration. This would have allowed efficient overplating and burial of early Martian crust in a stagnant-lid tectonic regime, in which the lithosphere comprised a single tectonic plate, with only the warmer, lower crust involved in mantle convection. This provided an important sink for hydrospheric water and a mechanism for oxidizing the Martian mantle. Conversely, relatively buoyant mafic crust and hotter geothermal gradients on Earth reduced the potential for upper-mantle hydration early in its geological history, leading to water being retained close to

Investigation of the Cooling Capacity of Plate Tectonics and Flood Volcanism in the Evolution of Earth, Mars and Venus

NASA Astrophysics Data System (ADS)

van Thienen, P.; Vlaar, N. J.; van den Berg, A. P.

2003-12-01

The cooling of the terrestrial planets from their presumed hot initial states to the present situation has required the operation of one or more efficient cooling mechanisms. In the recent history of the Earth, plate tectonics has been responsible for most of the planetary cooling. The high internal temperature of the early Earth, however, prevented the operation of plate tectonics because of the greater inherent buoyancy of thicker oceanic lithosphere (basaltic crust and depleted mantle) produced from a hotter mantle. A similar argument is valid for Venus, and also for Mars. An alternative cooling mechanism may therefore have been required during a part of the planetary histories. Starting from the notion that all heat output of planets is through their surfaces, we have constructed two parametric models to evaluate the cooling characteristics of two cooling mechanisms: plate tectonics and basalt extrusion / flood volcanism. We have applied these models to the Earth, Mars and Venus for present-day and presumed early thermal conditions. Our model results show that for a steadily (exponentially) cooling Earth, plate tectonics is capable of removing all the required heat at a rate comparable to or even lower than its current rate of operation during its entire history, contrary to earlier speculations. The extrusion mechanism may have been an important cooling agent in the early Earth, but requires global eruption rates two orders of magnitude greater than those of known Phanerozoic flood basalt provinces. This may not be a problem, since geological observations indicate that flood volcanism was both stronger and more ubiquitous in the early Earth. Because of its smaller size, Mars is capable of cooling conductively through its lithosphere at significant rates. As a result may have cooled without an additional cooling mechanism during its entire history. Venus, on the other hand, has required the operation of an additional cooling agent for probably every cooling

Exploring the Surface of Titan with Cassini-Huygens

NASA Astrophysics Data System (ADS)

Turtle, E. P.; Barnes, J.; Buratti, B. J.; Collins, G.; Fussner, S.; Lopes, R.; Lorenz, R. D.; Lunine, J. I.; McCord, T. B.; McEwen, A. S.; Nelson, R.; Perry, J.; Porco, C. C.; Soderblom, L.; Sotin, C.; Wall, S. D.

2005-12-01

Over the past year, the Cassini-Huygens mission has returned a wealth of data about the surface of Saturn's satellite Titan. Cassini's Imaging Science Subsystem (ISS), RADAR, and Visual and Infrared Mapping Spectrometer (VIMS), and Huygens' Descent Imaging Spectral Radiometer (DISR) have revealed an intriguing surface that is at once familiar and alien. Although water-ice and liquid hydrocarbons play the roles that rock and water play on Earth, the surface appears to have been worked by a wide variety of processes resulting in a seemingly Earth-like balance of fluvial, aeolian, and volcanic features, with relatively few impact craters. There seem to be at least two classes of surface material: dark areas (at visible-IR wavelengths) that are spectrally consistent with contaminated water ice, and brighter areas of unknown composition which show greater variations. The expected bodies of liquids have yet to be definitively identified; however, circumstantial evidence for liquids having acted upon the surface in Titan's past is abundant, primarily in the form of channels, and possible ponds or lakes, which have been observed by multiple instruments. Other features suggest that wind redistributes some surface materials, most likely the detritus of the complex atmospheric chemistry, creating diffuse IR-bright deposits and long, narrow, radar-dark (2.2-cm) stripes, all of which trend generally east-west. Only two impact structures have been identified to date, although several other suspiciously circular features have been documented. A variety of the morphologies observed bear strong resemblances to volcanic structures. A number of other features remain mysterious and further co-analysis of these data sets, as well as the anticipated acquisition of more data, will be needed to fully understand the nature of Titan's surface, the albedo variations observed at different wavelengths, and the processes that have acted upon it (and may continue to). In addition to the Huygens

A Hands-on Exploration of the Retrograde Motion of Mars as Seen from the Earth

ERIC Educational Resources Information Center

Pincelli, M. M.; Otranto, S.

2013-01-01

In this paper, we propose a set of activities based on the use of a celestial simulator to gain insights into the retrograde motion of Mars as seen from the Earth. These activities provide a useful link between the heliocentric concepts taught in schools and those tackled in typical introductory physics courses based on classical mechanics for…

Titan's Atmosphere and Surface Explored by Future in Situ Balloon Investigations

NASA Astrophysics Data System (ADS)

Coustenis, Athena; OPAG Titan Working Group

2009-09-01

A wide range of high priority scientific questions for Titan remain to be addressed after Cassini-Huygens, some of which cannot be comprehensively addressed by any envisioned extension of Cassini flybys due to its inherent limitations and require both remote and in situ investigation. Whereas a spacecraft in orbit around Titan could allow for a thorough investigation of Titan's upper atmosphere, there are questions that can only be answered by extending the measurements into Titan's lower atmosphere and down to the surface. Key steps toward the synthesis of prebiotic molecules that may have been present on the early Earth as precursors to life might be occurring high in the atmosphere, the products then descending towards the surface where they might replicate. In situ chemical analysis of gases, liquids and solids, both in the atmosphere and on the surface, would enable the identification of chemical species that are present and how far such putative reactions have advanced. The rich inventory of complex organic molecules that are known or suspected to be present in the lower atmosphere and at the surface gives Titan a strong astrobiological potential. Our understanding of the forces that shape Titan's diverse landscape and interior will benefit greatly from detailed investigations at a variety of locations, a demanding requirement anywhere else, but one that is uniquely possible at Titan using a hot-air balloon (montgolfière). Indeed, Titan's thick cold atmosphere and low gravity make the deployment of in situ elements using parachutes (as demonstrated by the Cassini-Huygens probe) and balloons vastly easier than for any other solar system body. A balloon floating across the Titan landscape for long periods of time, with an adapted payload, would offer the mobility required to explore the diversity of Titan in a way that cannot be achieved with any other platform.

Properties of thermospheric gravity waves on earth, Venus and Mars

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

The atmospheric escape at Mars: complementing the scenario

NASA Astrophysics Data System (ADS)

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

2013-04-01

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

An Efficient Approach for Mars Sample Return Using Emerging Commercial Capabilities

NASA Technical Reports Server (NTRS)

Gonzales, Andrew A.; Stoker, Carol R.

2016-01-01

Mars Sample Return is the highest priority science mission for the next decade as recommended by the 2011 Decadal Survey of Planetary Science. This article presents the results of a feasibility study for a Mars Sample Return mission that efficiently uses emerging commercial capabilities expected to be available in the near future. The motivation of our study was the recognition that emerging commercial capabilities might be used to perform Mars Sample Return with an Earth-direct architecture, and that this may offer a desirable simpler and lower cost approach. The objective of the study was to determine whether these capabilities can be used to optimize the number of mission systems and launches required to return the samples, with the goal of achieving the desired simplicity. All of the major element required for the Mars Sample Return mission are described. Mission system elements were analyzed with either direct techniques or by using parametric mass estimating relationships. The analysis shows the feasibility of a complete and closed Mars Sample Return mission design based on the following scenario: A SpaceX Falcon Heavy launch vehicle places a modified version of a SpaceX Dragon capsule, referred to as "Red Dragon", onto a Trans Mars Injection trajectory. The capsule carries all the hardware needed to return to Earth Orbit samples collected by a prior mission, such as the planned NASA Mars 2020 sample collection rover. The payload includes a fully fueled Mars Ascent Vehicle; a fueled Earth Return Vehicle, support equipment, and a mechanism to transfer samples from the sample cache system onboard the rover to the Earth Return Vehicle. The Red Dragon descends to land on the surface of Mars using Supersonic Retropropulsion. After collected samples are transferred to the Earth Return Vehicle, the single-stage Mars Ascent Vehicle launches the Earth Return Vehicle from the surface of Mars to a Mars phasing orbit. After a brief phasing period, the Earth Return

An efficient approach for Mars Sample Return using emerging commercial capabilities

NASA Astrophysics Data System (ADS)

Gonzales, Andrew A.; Stoker, Carol R.

2016-06-01

Mars Sample Return is the highest priority science mission for the next decade as recommended by the 2011 Decadal Survey of Planetary Science (Squyres, 2011 [1]). This article presents the results of a feasibility study for a Mars Sample Return mission that efficiently uses emerging commercial capabilities expected to be available in the near future. The motivation of our study was the recognition that emerging commercial capabilities might be used to perform Mars Sample Return with an Earth-direct architecture, and that this may offer a desirable simpler and lower cost approach. The objective of the study was to determine whether these capabilities can be used to optimize the number of mission systems and launches required to return the samples, with the goal of achieving the desired simplicity. All of the major element required for the Mars Sample Return mission are described. Mission system elements were analyzed with either direct techniques or by using parametric mass estimating relationships. The analysis shows the feasibility of a complete and closed Mars Sample Return mission design based on the following scenario: A SpaceX Falcon Heavy launch vehicle places a modified version of a SpaceX Dragon capsule, referred to as ;Red Dragon;, onto a Trans Mars Injection trajectory. The capsule carries all the hardware needed to return to Earth Orbit samples collected by a prior mission, such as the planned NASA Mars 2020 sample collection rover. The payload includes a fully fueled Mars Ascent Vehicle; a fueled Earth Return Vehicle, support equipment, and a mechanism to transfer samples from the sample cache system onboard the rover to the Earth Return Vehicle. The Red Dragon descends to land on the surface of Mars using Supersonic Retropropulsion. After collected samples are transferred to the Earth Return Vehicle, the single-stage Mars Ascent Vehicle launches the Earth Return Vehicle from the surface of Mars to a Mars phasing orbit. After a brief phasing period, the

An Efficient Approach for Mars Sample Return Using Emerging Commercial Capabilities.

PubMed

Gonzales, Andrew A; Stoker, Carol R

2016-06-01

Mars Sample Return is the highest priority science mission for the next decade as recommended by the 2011 Decadal Survey of Planetary Science [1]. This article presents the results of a feasibility study for a Mars Sample Return mission that efficiently uses emerging commercial capabilities expected to be available in the near future. The motivation of our study was the recognition that emerging commercial capabilities might be used to perform Mars Sample Return with an Earth-direct architecture, and that this may offer a desirable simpler and lower cost approach. The objective of the study was to determine whether these capabilities can be used to optimize the number of mission systems and launches required to return the samples, with the goal of achieving the desired simplicity. All of the major element required for the Mars Sample Return mission are described. Mission system elements were analyzed with either direct techniques or by using parametric mass estimating relationships. The analysis shows the feasibility of a complete and closed Mars Sample Return mission design based on the following scenario: A SpaceX Falcon Heavy launch vehicle places a modified version of a SpaceX Dragon capsule, referred to as "Red Dragon", onto a Trans Mars Injection trajectory. The capsule carries all the hardware needed to return to Earth Orbit samples collected by a prior mission, such as the planned NASA Mars 2020 sample collection rover. The payload includes a fully fueled Mars Ascent Vehicle; a fueled Earth Return Vehicle, support equipment, and a mechanism to transfer samples from the sample cache system onboard the rover to the Earth Return Vehicle. The Red Dragon descends to land on the surface of Mars using Supersonic Retropropulsion. After collected samples are transferred to the Earth Return Vehicle, the single-stage Mars Ascent Vehicle launches the Earth Return Vehicle from the surface of Mars to a Mars phasing orbit. After a brief phasing period, the Earth Return

Habitability: Where to look for life? Halophilic habitats: Earth analogs to study Mars habitability

NASA Astrophysics Data System (ADS)

Gómez, F.; Rodríguez-Manfredi, J. A.; Rodríguez, N.; Fernández-Sampedro, M.; Caballero-Castrejón, F. J.; Amils, R.

2012-08-01

Oxidative stress, high radiation doses, low temperature and pressure are parameters which made Mars's surface adverse for life. Those conditions found on Mars surface are harsh conditions for life to deal with. Life, as we know it on Earth, needs several requirements for its establishment but, the only "sine qua nom" element is water. Extremophilic microorganisms widened the window of possibilities for life to develop in the universe, and as a consequence on Mars. Recently reported results in extreme environments indicate the possibility of presence of "oasys" for life in microniches due to water deliquescence in salts deposits. The compilation of data produced by the ongoing missions (Mars Global Surveyor, Mars Odyssey, Mars Express and Mars Exploration Rover Opportunity) offers a completely different view from that reported by Viking missions: signs of an early wet Mars and rather recent volcanic activity. The discovery of important accumulations of sulfates, and the existence of iron minerals like jarosite, goethite and hematite in rocks of sedimentary origin has allowed specific terrestrial models related with this type of mineralogy to come into focus. Río Tinto (Southwestern Spain, Iberian Pyritic Belt) is an extreme acidic environment, product of the chemolithotrophic activity of microorganisms that thrive in the massive pyrite-rich deposits of the Iberian Pyritic Belt. The high concentration of ferric iron and sulfates, products of the metabolism of pyrite, generate a collection of minerals, mainly gypsum, jarosite, goethite and hematites, all of which have been detected in different regions of Mars. Some particular protective environments or elements could house organic molecules or the first bacterial life forms on Mars surface. Terrestrial analogs could help us to afford its comprehension. We are reporting here some preliminary studies about endolithic niches inside salt deposits used by phototrophs for taking advantage of sheltering particular light

Mesoscale raised rim depressions (MRRDs) on Earth: A review of the characteristics, processes, and spatial distributions of analogs for Mars

USGS Publications Warehouse

Burr, D.M.; Bruno, B.C.; Lanagan, P.D.; Glaze, L.S.; Jaeger, W.L.; Soare, R.J.; Wan, Bun Tseung J.-M.; Skinner, J.A.; Baloga, S.M.

2009-01-01

Fields of mesoscale raised rim depressions (MRRDs) of various origins are found on Earth and Mars. Examples include rootless cones, mud volcanoes, collapsed pingos, rimmed kettle holes, and basaltic ring structures. Correct identification of MRRDs on Mars is valuable because different MRRD types have different geologic and/or climatic implications and are often associated with volcanism and/or water, which may provide locales for biotic or prebiotic activity. In order to facilitate correct identification of fields of MRRDs on Mars and their implications, this work provides a review of common terrestrial MRRD types that occur in fields. In this review, MRRDs by formation mechanism, including hydrovolcanic (phreatomagmatic cones, basaltic ring structures), sedimentological (mud volcanoes), and ice-related (pingos, volatile ice-block forms) mechanisms. For each broad mechanism, we present a comparative synopsis of (i) morphology and observations, (ii) physical formation processes, and (iii) published hypothesized locations on Mars. Because the morphology for MRRDs may be ambiguous, an additional tool is provided for distinguishing fields of MRRDs by origin on Mars, namely, spatial distribution analyses for MRRDs within fields on Earth. We find that MRRDs have both distinguishing and similar characteristics, and observation that applies both to their mesoscale morphology and to their spatial distribution statistics. Thus, this review provides tools for distinguishing between various MRRDs, while highlighting the utility of the multiple working hypotheses approach. ?? 2008 Elsevier Ltd.

Mesoscale Raised Rim Depressions (MRRDs) on Earth: A Review of the Characteristics, Processes, and Spatial Distributions of Analogs for Mars

NASA Technical Reports Server (NTRS)

Burr, Devon M.; Bruno, Barbara C.; Lanagan, Peter D.; Glaze, Lori; Jaeger, Windy L.; Soare, Richard J.; Tseung, Jean-Michel Wan Bun; Skinner, James A. Jr.; Baloga, Stephen M.

2008-01-01

Fields of mesoscale raised rim depressions (MRRDs) of various origins are found on Earth and Mars. Examples include rootless cones, mud volcanoes, collapsed pingos, rimmed kettle holes, and basaltic ring structures. Correct identification of MRRDs on Mars is valuable because different MRRD types have different geologic and/or climatic implications and are often associated with volcanism and/or water, which may provide locales for biotic or prebiotic activity. In order to facilitate correct identification of fields of MRRDs on Mars and their implications, this work provides a review of common terrestrial MRRD types that occur in fields. In this review, MRRDs by formation mechanism, including hydrovolcanic (phreatomagmatic cones, basaltic ring structures), sedimentological (mud volcanoes), and ice-related (pingos, volatile ice-block forms) mechanisms. For each broad mechanism, we present a comparative synopsis of (i) morphology and observations, (ii) physical formation processes, and (iii) published hypothesized locations on Mars. Because the morphology for MRRDs may be ambiguous, an additional tool is provided for distinguishing fields of MRRDs by origin on Mars, namely, spatial distribution analyses for MRRDs within fields on Earth. We find that MRRDs have both distinguishing and similar characteristics, and observation that applies both to their mesoscale morphology and to their spatial distribution statistics. Thus, this review provides tools for distinguishing between various MRRDs, while highlighting the utility of the multiple working hypotheses approach.

ALMA observations of Titan's atmospheric chemistry and seasonal variation

NASA Astrophysics Data System (ADS)

Cordiner, Martin

2017-04-01

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