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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Noble gases in planetary atmospheres - Implications for the origin and evolution of atmospheres

The radiogenic and primordial noble gas contents of the Venus, earth, and Mars atmospheres are compared with one another and with the noble gas content of other extraterrestrial samples, particularly meteorites. Key trends in the primordial noble gas content of terrestrial planetary atmospheres are shown to include: (1) a several-orders-of-magnitude decrease in Ne-20 and Ar-36 from Venus to earth to Mars; (2) a nearly constant Ne-20/Ar-36 ratio, which is comparable to that found in the more primitive carbonaceous chondrites and which is two orders of magnitude smaller than the solar ratio; (3) a sizable fractionation of Ar, Kr, and Xe from their solar ratios, though the degree of fractionation (especially for Ar-36/Xe-132) appears to decrease systematically from carbonaceous chondrites to Mars to earth to Venus; and (4) large differences in Ne and Xe isotopic ratios among earth, meteorites, and the sun. It is suggested that the grain-accretion hypothesis can explain all four trends, though the assumptions needed to achieve this agreement are far from proven.

Pollack, J. B.↗
NASA NTRS1988

Climatology of the stratospheric polar vortex and planetary wave breaking

The distribution of Ertel's potential vorticity (PV) on the 850 K isentropic surface is used to establish a climatology for the transient evolution of the planetary scale circulation in the Northern Hemisphere winter midstratosphere. PV distributions are computed from gridded NMC daily temperature and height maps for the 10 and 30 mb levels, and show that a very good approximation for 850 K PV can be derived from 10 mb heights and temperatures alone. It is assumed that reversals of the latitudinal gradient of PV, localized in longitude and latitude may be regarded as signatures of planetary wave breaking. Wave breaking identified by such signatures tends to occur mainly in the vicinity of the Aleutian anticyclone, with a secondary maximum over Europe. The area of the polar vortex, defined as the area enclosed by PV contours greater than a certain critical value, is strongly influenced by wave breaking. Erosion of the polar vortex due to transport and mixing of PV leads to a preconditioned state, when defined in terms of vortex area, that always occurs prior to major stratospheric warmings. During winters with little PV transport or mixing, the vortex area evolves rather uniformly in response to radiative forcing. During winters with major sudden warmings, the wave breaking signature as defined here first appears at low values of PV, then rapidly moves toward higher values as the vortex area is reduced and the 'surf-zone' structure becomes well defined.

Baldwin, Mark P.↗
NASA NTRS1975

Experimental Evaluation of Silica as a Thermal Protection System for Planetary Entry Probes

The evolution and pursuit of the reflecting heat-shield concept has resulted in a refined and sophisticated high-performance material: ultra-pure, slip-cast, fused silica (SCFS). Silica is "tailored" to the intense planetary entry environments through a combination of its good ablative qualities and outstanding reflective properties in the correct spectral region. Extensive development of SCFS has produced a series of candidate materials which are experimentally evaluated and compared in a simulated entry environment. The detailed response of silica to combined heating is discussed, and the relative merits of SCFS and carbon phenolic are indicated.

David L Peterson↗
NASA NTRS1986

A Space Station-based search for other planetary systems

The physical forces shaping and maintaining the form of the solar system and disk galaxies are reviewed to define the basis for an observational campaign from the Space Station, to find other planetary systems. The evolution of the distribution of types of matter in the solar system is regarded as typical of the formation of planetary systems around other stars. The observation campaign would cover 100 stars out to 10 pc and last 15-30 yr. Technological challenges which must be met to realize the telescope on the Station are described.

Levy, E. H.↗
NASA NTRS2003

Probability of Detecting Planets with Microlensing

The proposed research to determine the probability of detecting extra solar planets from the ground with microlensing was completely accomplished during the grant period. A summary of the publications and their abstracts follow below. The publications include: 1) On microlensing rates and optical depth toward the Galactic center; 2) Newly discovered brown dwarfs not seen in microlensing timescale frequency distribution? 3) Probability of detecting a planetary companion during a microlensing event; 4) Comparison of a ground-based microlensing search for planets with a search from space; 5) Secular evolution of hierarchical planetary systems.

Peale, S. J.↗
NASA NTRS2015

Investigating the Origin and Evolution of Venus with In Situ Mass Spectrometry

The exploration of Venus continues to be a top priority of planetary science. The Planetary Decadal Survey goals for inner-planet exploration seek to discern the origin and diversity of terrestrial planets, understand how the evolution of terrestrial planets relates to the evolution of life, and explore the processes that control climate on Earth-like planets. These goals can only be realized through continued and extensive exploration of Venus, the most mysterious of the terrestrial planets, remarkably different from the Earth despite the gross similarities between these "twin planets". It is unknown if this apparent divergence was intrinsic, programmed during accretion from distinct nebular reservoirs, or a consequence of either measured or catastrophic processes during planetary evolution. Even if the atmosphere of Venus is a more "recent" development, its relationship to the resurfacing of the planet's enigmatic surface is not well understood. Resolving such uncertainties directly addresses the hypothesis of a more clement, possibly water-rich era in Venus' past as well as whether Earth could become more Venus-like in the future.

Venus↗
NASA NTRS2016

Investigating the Origin and Evolution of Venus with in Situ Mass Spectrometry

The exploration of Venus continues to be a top priority of planetary science. The Planetary Decadal Survey goals for inner-planet exploration seek to discern the origin and diversity of terrestrial planets, understand how the evolution of terrestrial planets relates to the evolution of life, and explore the processes that control climate on Earth-like planets. These goals can only be realized through continued and extensive exploration of Venus, the most mysterious of the terrestrial planets, remarkably different from the Earth despite the gross similarities between these "twin planets". It is unknown if this apparent divergence was intrinsic, programmed during accretion from distinct nebular reservoirs, or a consequence of either measured or catastrophic processes during planetary evolution. Even if the atmosphere of Venus is a more "recent" development, its relationship to the resurfacing of the planet's enigmatic surface is not well understood. Resolving such uncertainties directly addresses the hypothesis of a more clement, possibly water-rich era in Venus' past as well as whether Earth could become more Venus-like in the future.

origin and evolution↗
NASA NTRS2014

Investigating the Origin and Evolution of Venus with In Situ Mass Spectrometry

The exploration of Venus continues to be a top priority of planetary science. The Planetary Decadal Survey goals for inner-planet exploration seek to discern the origin and diversity of terrestrial planets, understand how the evolution of terrestrial planets relates to the evolution of life, and explore the processes that control climate on Earth-like planets [1]. These goals can only be realized through continued and extensive exploration of Venus, the most mysterious of the terrestrial planets, remarkably different from the Earth despite the gross similarities between these twin planets. It is unknown if this apparent divergence was intrinsic, programmed during accretion from distinct nebular reservoirs, or a consequence of either measured or catastrophic processes during planetary evolution. Even if the atmosphere of Venus is a more recent development, its relationship to the resurfacing of the planets enigmatic surface is not well understood. Resolving such uncertainties directly addresses the hypothesis of a more clement, possibly water-rich era in Venus past as well as whether Earth could become more Venus-like in the future.

earth-like planets↗
NASA NTRS1994

The expected morphology of the solar system planetary nebula

We examine the evolution of Jupiter's orbit as the Sun evolves to form a planetary nebula. We use an orbital synchronization mechanism, which was proposed by Tassoul (1987, ApJ, 322, 856), and find that Jupiter is likely to deposit a substantial fraction of its orbital angular momentum, in spinning-up the Sun, when the latter is on the upper Asymptotic Giant Branch (AGB). This amount of angular momentum is likely to cause some small degree of axisymmetric mass loss from the Sun. In this case, the Sun will form an elliptical planetary nebula. The formation of elliptical planetary nebulae with the influence of massive planets and brown dwarfs, may explain the large fraction of elliptical planetary nebulae among the total number of planetary nebulae known today.

Soker, Noam↗
NASA NTRS2009

Planetary Geologic Mapping Handbook - 2009

Geologic maps present, in an historical context, fundamental syntheses of interpretations of the materials, landforms, structures, and processes that characterize planetary surfaces and shallow subsurfaces (e.g., Varnes, 1974). Such maps also provide a contextual framework for summarizing and evaluating thematic research for a given region or body. In planetary exploration, for example, geologic maps are used for specialized investigations such as targeting regions of interest for data collection and for characterizing sites for landed missions. Whereas most modern terrestrial geologic maps are constructed from regional views provided by remote sensing data and supplemented in detail by field-based observations and measurements, planetary maps have been largely based on analyses of orbital photography. For planetary bodies in particular, geologic maps commonly represent a snapshot of a surface, because they are based on available information at a time when new data are still being acquired. Thus the field of planetary geologic mapping has been evolving rapidly to embrace the use of new data and modern technology and to accommodate the growing needs of planetary exploration. Planetary geologic maps have been published by the U.S. Geological Survey (USGS) since 1962 (Hackman, 1962). Over this time, numerous maps of several planetary bodies have been prepared at a variety of scales and projections using the best available image and topographic bases. Early geologic map bases commonly consisted of hand-mosaicked photographs or airbrushed shaded-relief views and geologic linework was manually drafted using mylar bases and ink drafting pens. Map publishing required a tedious process of scribing, color peel-coat preparation, typesetting, and photo-laboratory work. Beginning in the 1990s, inexpensive computing, display capability and user-friendly illustration software allowed maps to be drawn using digital tools rather than pen and ink, and mylar bases became obsolete. Terrestrial geologic maps published by the USGS now are primarily digital products using geographic information system (GIS) software and file formats. GIS mapping tools permit easy spatial comparison, generation, importation, manipulation, and analysis of multiple raster image, gridded, and vector data sets. GIS software has also permitted the development of project-specific tools and the sharing of geospatial products among researchers. GIS approaches are now being used in planetary geologic mapping as well (e.g., Hare and others, 2009). Guidelines or handbooks on techniques in planetary geologic mapping have been developed periodically (e.g., Wilhelms, 1972, 1990; Tanaka and others, 1994). As records of the heritage of mapping methods and data, these remain extremely useful guides. However, many of the fundamental aspects of earlier mapping handbooks have evolved significantly, and a comprehensive review of currently accepted mapping methodologies is now warranted. As documented in this handbook, such a review incorporates additional guidelines developed in recent years for planetary geologic mapping by the NASA Planetary Geology and Geophysics (PGG) Program s Planetary Cartography and Geologic Mapping Working Group s (PCGMWG) Geologic Mapping Subcommittee (GEMS) on the selection and use of map bases as well as map preparation, review, publication, and distribution. In light of the current boom in planetary exploration and the ongoing rapid evolution of available data for planetary mapping, this handbook is especially timely.

Tanaka, K. L.↗
NASA NTRS2010

Planetary Geologic Mapping Handbook - 2010

Geologic maps present, in an historical context, fundamental syntheses of interpretations of the materials, landforms, structures, and processes that characterize planetary surfaces and shallow subsurfaces. Such maps also provide a contextual framework for summarizing and evaluating thematic research for a given region or body. In planetary exploration, for example, geologic maps are used for specialized investigations such as targeting regions of interest for data collection and for characterizing sites for landed missions. Whereas most modern terrestrial geologic maps are constructed from regional views provided by remote sensing data and supplemented in detail by field-based observations and measurements, planetary maps have been largely based on analyses of orbital photography. For planetary bodies in particular, geologic maps commonly represent a snapshot of a surface, because they are based on available information at a time when new data are still being acquired. Thus the field of planetary geologic mapping has been evolving rapidly to embrace the use of new data and modern technology and to accommodate the growing needs of planetary exploration. Planetary geologic maps have been published by the U.S. Geological Survey (USGS) since 1962. Over this time, numerous maps of several planetary bodies have been prepared at a variety of scales and projections using the best available image and topographic bases. Early geologic map bases commonly consisted of hand-mosaicked photographs or airbrushed shaded-relief views and geologic linework was manually drafted using mylar bases and ink drafting pens. Map publishing required a tedious process of scribing, color peel-coat preparation, typesetting, and photo-laboratory work. Beginning in the 1990s, inexpensive computing, display capability and user-friendly illustration software allowed maps to be drawn using digital tools rather than pen and ink, and mylar bases became obsolete. Terrestrial geologic maps published by the USGS now are primarily digital products using geographic information system (GIS) software and file formats. GIS mapping tools permit easy spatial comparison, generation, importation, manipulation, and analysis of multiple raster image, gridded, and vector data sets. GIS software has also permitted the development of projectspecific tools and the sharing of geospatial products among researchers. GIS approaches are now being used in planetary geologic mapping as well. Guidelines or handbooks on techniques in planetary geologic mapping have been developed periodically. As records of the heritage of mapping methods and data, these remain extremely useful guides. However, many of the fundamental aspects of earlier mapping handbooks have evolved significantly, and a comprehensive review of currently accepted mapping methodologies is now warranted. As documented in this handbook, such a review incorporates additional guidelines developed in recent years for planetary geologic mapping by the NASA Planetary Geology and Geophysics (PGG) Program's Planetary Cartography and Geologic Mapping Working Group's (PCGMWG) Geologic Mapping Subcommittee (GEMS) on the selection and use of map bases as well as map preparation, review, publication, and distribution. In light of the current boom in planetary exploration and the ongoing rapid evolution of available data for planetary mapping, this handbook is especially timely.

Tanaka, K. L.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Lunar Sample Analysis

The titles in this section include: 1) Global Mixing as a Mechanism for Compositional Anomalies of Agglutinitic Glasses; 2) Electron Microscopy of Apollo 12 Glass Spherules; 3) 40Ar-39Ar Geochronology on Apollo 12 Regolith; 4) LSCC Apollo and Luna Soil Analyses: Update of Soil Evolution Model; 5) Planetary Regolith Microstructure: An Unexpected Opposition Effect Result; 6) Infrared Spectroscopy on a Microscopic Scale: Investigating the Technique of Microspectroscopy and Its Application to a Lunar Breccia; 7) The Most Reduced Rock from the Moon - Apollo 14 Basalt 14053: Extreme Reduction Entirely from a Re-Heating Event.

Source record↗
NASA NTRS1988

Risk to civilization: A planetary science perspective

One of the most profound changes in our perspective of the solar system resulting from the first quarter century of planetary exploration by spacecraft is the recognition that planets, including Earth, were bombarded by cosmic projectiles for 4.5 aeons and continue to be bombarded today. Although the planetary cratering rate is much lower now than it was during the first 0.5 aeons, sizeable Earth-approaching asteroids and comets continue to hit the Earth at a rate that poses a finite risk to civilization. The evolution of this planetary perspective on impact cratering is gradual over the last two decades. It took explorations of Mars and Mercury by early Mariner spacecraft and of the outer solar system by the Voyagers to reveal the significance of asteroidal and cometary impacts in shaping the morphologies and even chemical compositions of the planets. An unsettling implication of the new perspective is addressed: the risk to human civilization. Serious scientific attention was given to this issue in July 1981 at a NASA-sponsored Spacewatch Workshop in Snowmass, Colorado. The basic conclusion of the 1981 NASA sponsored workshop still stands: the risk that civilization might be destroyed by impact with an as-yet-undiscovered asteroid or comet exceeds risk levels that are sometimes deemed unacceptable by modern societies in other contexts. Yet these impact risks have gone almost undiscussed and undebated. The tentative quantitative assessment by some members of the 1981 workshop was that each year, civilization is threatened with destruction with a probability of about 1 in 100,000. The enormous spread in risk levels deemed by the public to be at the threshold of acceptability derives from a host of psychological factors that were widely discussed in the risk assessment literature. Slovic shows that public fears of hazards are greatest for hazards that are uncontrollable, involuntary, fatal, dreadful, globally catastrophic, and which have consequences that seem inequitable, especially if they affect future generations.

Chapman, Clark R.↗
NASA NTRS1985

Primordial magmaspheres and their lasting consequences

The lunar magmasphere is a useful but potentially misleading analog for the earliest evolution of other planetary objects. A significant fraction of the lunar magmasphere became a crust rich in buoyant cumulus plagioclase. Another significant fraction became a series of ultramafic cumulates (the mare basalt sources) complementary to the anorthosite. These events predetermined all subsequent lunar evolution. Empirically, the Moon was big enough to produce a magmasphere. Beyond a depth limit of roughly 200 km, nearly independent of the size of the planet, the remainder of the magmasphere will probably at all times be a single convective, and therefore essentially non-differentiating layer. The fraction of the mantle contained in the outer 200 km is of course inversely related to planet size. Compared to the Moon the Earth's mantle comprises a volume of 40 x greater and a pressure range 30 x greater. Steeper dP/dZ, favoring garnets and pyroxenes, also works to dampen differentiation in larger planets. One long term consequence of the Earth's magmasphere was probably a depletion of H2O in much of the mantle. Because water is a flux for mantle convection, anhydrous parts of the mantle probably had anomalously thick lithospheres and hot asthenospheres.

Warren, P. H.↗
NASA NTRS1984

Lithospheric stresses due to radiogenic heating of an ice-silicate planetary body - Implications for Ganymede's tectonic evolution

Thermal evolution models of differentiated and undifferentiated ice-silicate bodies containing long-lived radiogenic heat sources are examined. Lithospheric sresses arise due to volume change of the interior and temperature change in the lithosphere. For an undifferentiated body, the surface stress peaks early in the evolution, while in the differentiated case, stresses peak later and continue to accumulate for longer periods of time. The variation of near-surface stress with depth shows that stresses for the undifferentiated body initially penetrate to great depths, but rapidly concentrate within a few kilometers of the surface. For the differentiated body, elastic stresses never accumulate at a depth greater than a few kilometers. These models are applied to consider long-term rdioactive heating as a possible mechanism of tectonic activity and bright terrain formation on Ganymede.

Zuber, M. T.↗
NASA NTRS1993

A Team Approach to the Development of Gamma Ray and x Ray Remote Sensing and in Situ Spectroscopy for Planetary Exploration Missions

An important part of the investigation of planetary origin and evolution is the determination of the surface composition of planets, comets, and asteroids. Measurements of discrete line X-ray and gamma ray emissions from condensed bodies in space can be used to obtain both qualitative and quantitative elemental composition information. The Planetary Instrumentation Definition and Development Program (PIDDP) X-Ray/Gamma Ray Team has been established to develop remote sensing and in situ technologies for future planetary exploration missions.

Trombka, J. I.↗