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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Mars - Remote spectral identification of H2O frost and mineral hydrate

A reflectance spectrum (0.62-2.6 microns) of Mars (integral disk) is obtained using a newly developed IR spectrometer at the 2.25 m telescope on Mauna Kea, Hawaii. Details of the instrument, observations, and data reduction are presented. Several distinct absorption features are evident that were apparently caused by H2O, but the positions and intensities of the features are quite unusual. In summary, the regolith is probably not as desiccated and dehydrated as the full disk reflectance spectrum and Viking soil analyses would suggest. The surface materials become desiccated and dehydrated as a result of solar UV effects and because of the relative adsorption and desorption rates during the strong diurnal cycling. There may be significant amounts of H2O at depth, and in the Solis Lacus region the H2O reservoir may extend to within a few centimeters of the surface. The Solis Lacus region may therefore be an important target for future Mars landing or sample return mission.

Huguenin, R. L.↗
NASA NTRS1982

Earth-crossing asteroids - New discoveries

An earth-crossing asteroid is an asteroid whose orbit will intersect the orbit of the earth as a result of secular perturbations. Astronomical observations have led to the discovery of 43 earth-crossing asteroids during the last fifty years. Nearly sixty percent of these were found in the decade 1971-1981. Noteworthy results of the last decade are discussed, taking into account the Aten asteroids, accidental rediscoveries, asteroids of possible cometary origin, candidates for rendezvous and sample return missions, and populations and collision rates with earth. The observed earth-crossing asteroids are listed in a table, and the orbits of earth, Mars, and four Atens projected on ecliptic plane are shown.

Helin, E. F.↗
NASA NTRS1983

Mars - A contamination potential?

Three regions on Mars, Solis Lacus, Noachis-Hellespontus, and the Syrtis Major border areas, would appear to have generally less hostile environments than at the Viking lander sites. Significant soil moisture may extend to within about 1 cm of the surface. Water vapor pressures within the pore spaces may be near saturation, and brines may be physically segregated from pockets of relatively pure H2O. Temperatures reach above 0 C during southern spring and summer, with peak temperatures reaching +22 C. These regions should contain fewer oxidants, and primary synthesis of organics may occur. The potential for contamination of these sites by microbes transported from existing spacecraft should be assessed. The adequacy of proposed new planetary protection procedures for possible future United States Mars Surface Sample Return missions should also be assessed in light of these findings.

Huguenin, R. L.↗
NASA NTRS1984

The discovery of 1982 DB, the most accessible asteroid known

A small Apollo object was found while photographing the split comet DuToit 2-Hartley on February 27/28, 1982. Designated 1982 DB, this earth-crossing asteroid passed the earth at a distance of 4.08 million km about 1 month prior to its discovery. Asteroid 1982 DB has been determined to be the most accessible near-earth minor planet known. It provides many excellent opportunities for rendezvous and sample return missions, and a rare dual rendezvous mission with 1980 AA as the second target. For a mission to be realized, opportunities to observe 1982 DB during future apparitions must be taken.

Helin, E. F.↗
NASA NTRS1985

Mars landing sites

An intensive effort has been underway for the past two years to study possible landing sites for a future Mars rover and returned-sample mission. The task has been to identify and study nine sites, each of which is near a variety of representative geologic units. The choice of sites is independent of future decisions as to whether the rovers will be manned or unmanned, except that unmanned rover traverses may be shorter and more restricted. North and south polar locations, the Grand canyon that exposes layered terrain, two stream channels, two volcanic centers, and two upland sites are under consideration.

Masursky, H.↗
NASA NTRS1987

Spacecraft mass trade-offs versus radio-frequency power and antenna size at 8 GHz and 32 GHz

The purpose of this analysis is to help determine the relative merits of 32 GHz over 8 GHz for future deep space communications. This analysis is only a piece of the overall analysis and only considers the downlink communication mass, power, and size comparisons for 8 and 32 GHz. Both parabolic antennas and flat-plate arrays are considered. The Mars Sample Return mission is considered in some detail as an example of the tradeoffs involved; for this mission the mass, power, and size show a definite advantage of roughly 2:1 in using the 32 GHz over 8 GHz.

Gilchriest, C. E.↗
NASA NTRS1986

Comet coma sample return

The feasibility of capturing comet dust with polymer foam, dense gas, and fiber collectors is discussed. Polystyrene foams seem suitable. For volatile capture, chemically active getters are suggested. A scenario for a low speed flyby sample return mission is outlined.

Tsou, P.↗
NASA NTRS1987

Numerical simulation of cometary nuclei. III - Internal temperatures of cometary nuclei

The thermal diffusion equation for the internal temperature of cometary nuclei is exactly solved by means of a one-dimensional numerical model in order to shed light on the complex behavior of these temperatures with varying orbital and thermal parameters and in order to consider possible cometary nucleus thermal evolution targets for comet rendezvous and/or sample-return missions. The concept of 'new' and 'old' comets, classified in terms of how many passages around the sun have been made, may take on new meaning in view of the present demonstration that differences in eccentricity between two comets having the same period and number of apparitions may yield significantly different internal temperature profiles.

Herman, Gary↗
NASA NTRS1988

Energy storage considerations for a robotic Mars surface sampler

A Mars Rover capable of obtaining surface samples will need a power system for motive power and to power scientific instrumentation. Several different power systems are considered along with a discussion of the location options. The weight and volume advantages of the different systems are described for a particular power profile. The conclusions are that a Mars Rover Sample Return Mission and Extended Mission can be accomplished utilizing photovoltaics and electrochemical storage.

Odonnell, Patricia M.↗
NASA NTRS1987

32 GHz deep space communications

The present analysis of the use of a 32-GHz (Ka-band) downlink for deep space communications notes significant benefits over current standard 8.4-GHz downlinks; the consequences of the 8-dB telemetry performance gain thus obtained is presently evaluated for the case of the Cassini and Mars Sample Return missions. This potential can only be realized, however, with upgradings of both the ground stations in the Deep Space Network and the spacecraft communications subsystem. Proposals are made for the use of a Ka-band beacon on the Mars observer spacecraft, as well as the demonstration of such a system aboard the CRAF.

Hansen, D. M.↗
NASA NTRS1988

The Mars Observer database

Mars Observer will study the surface, atmosphere, and climate of Mars in a systematic way over an entire Martian year. The observations of the surface will provide a database that will be invaluable to the planning of a future Mars sample return mission. Mars Observer is planned for a September 1992 launch from the Space Shuttle, using an upper-stage. After the one year transit the spacecraft is injected into orbit about Mars and the orbit adjusted to a near-circular, sun-synchronous low-altitude, polar orbit. During the Martian year in this mapping orbit the instruments gather both geoscience data and climatological data by repetitive global mapping. The scientific objectives of the mission are to: (1) determine the global elemental and mineralogical character of the surface material; (2) define globally the topography and gravitational field; (3) establish the nature of the magnetic field; (4) determine the time and space distribution, abundance, sources, and sinks of volatile material and dust over a seasonal cycle; and (5) explore the structure and aspects of the circulation of the atmosphere. The science investigations and instruments for Mars Observer have been chosen with these objectives in mind. These instruments, the principal investigator or team leader and the objectives are discussed.

Albee, Arden L.↗
NASA NTRS1988

The soils of Mars

A mineralogical model for the Mars fine soil that includes as major components smectite clays absorbed and coated with amorphous iron oxyhydroxides and perhaps mixed with small amounts of better-crystalized iron oxides as separate phases is proposed. Also present as accessory minerals are sulfate minerals such as kieserite (MgSO4.H2O) and/or anhydrite (CaSO4), rutile (TiO2), and maghemite (Fe2O3) or magnetite (Fe3O4), the last two as magnetic components. Carbonates may be present at low concentrations only (less than 1 to 2 pct). However, a prime question to be addressed by a Mars Sample Return Mission shall be related to the mineralogical composition of the soil, and its spatial variability.

Banin, A.↗
NASA NTRS1988

Valles Marineris, Mars: An optimum science-sample site

The Valles Marineris troughs offer an opportunity to sample rocks that reflect various ages and compositions, giving insight into important processes on Mars. Most of the samples would be located within reasonable proximity and could be easily reached by rovers or balloons. Although landing a spacecraft on the floor of the Valles Marineris may be too dangerous for the first sample-return mission to Mars, the scientific rewards would be so great that such a landing should be considered for later flights.

Lucchitta, B. K.↗
NASA NTRS1988

Martian sediments and sedimentary rocks

Martian sediments and sedimentary rocks, clastic and nonclastic, should represent a high priority target in any future return-sample mission. The discovery of such materials and their subsequent analysis in terrestrial laboratories, would greatly increase the understanding of the Martian paleoclimate. The formation of Martian clastic sedimentary rocks, under either present, low-pressure, xeric conditions or a postulated, high-pressure, hydric environment, depends upon the existence of a supply of particles, various cementing agents and depositional basins. A very high resolution (mm-cm range) photographic reconnaissance of these areas would produce a quantum jump in the understanding of Martian geological history. Sampling would be confined to more horizontal (recent) surfaces. Exploration techniques are suggested for various hypothetical Martian sedimentary rocks.

Markun, C. D.↗
NASA NTRS1988

Mars orbital tethered sample return: The feasibility and uses of obtaining entrained particulates from the atmosphere

By employing technology developed for the Tethered Satellite Program, it appears feasible to obtain Martian dust samples from the atmosphere using an orbiting spacecraft. If collected during an annual dust storm, such a sample would contain a global selection of windborne materials. Atmospheric dust sampling is of importance to the study of Martian surface geochemistry, soil mechanics, atmospheric dynamics, and atmospheric and radiative transfer. Tethered sample return offers two key advantages over a lander sample return: relative simplicity and low spacecraft weight. In another vein, the collection of atmospheric dust by a lander sample return mission is itself of scientific merit. By employing a mast and collection plate aboard a lander mission, it is possible to obtain dust from distant locations transported as entrained material in the local aeolian environment.

Stern, S. A.↗
NASA NTRS1988

Computer modeling of the mineralogy of the Martian surface, as modified by aqueous alteration

Mineralogical constraints can be placed on the Martian surface by assuming chemical equilibria among the surface rocks, atmosphere and hypothesized percolating groundwater. A study was made of possible Martian surface mineralogy, as modified by the action of aqueous alteration, using the EQ3/6 computer codes. These codes calculate gas fugacities, aqueous speciation, ionic strength, pH, Eh and concentration and degree of mineral saturation for complex aqueous systems. Thus, these codes are also able to consider mineralogical solid solutions. These codes are able to predict the likely alteration phases which will occur as the result of weathering on the Martian surface. Knowledge of the stability conditions of these phases will then assist in the definition of the specifications for the sample canister of the proposed Martian sample return mission. The model and its results are discussed.

Zolensky, M. E.↗
NASA NTRS1989

Viking and Mars Rover exobiology

Other than Earth, Mars is the planet generating the greatest interest among those researching and contemplating the origin and distribution of life throughout the universe. The similarity of the early environments of Earth and Mars, and the biological evolution on early Earth provides the motivation to seriously consider the possibility of a primordial Martian biosphere. In 1975 the Viking project launched two unmanned spacecraft to Mars with the intent of finding evidence of the existence of present or past life on this planet. Three Viking Biology experiments were employed: the Labeled Release experiment, the Gas Exchange Experiment, and the Pyrolytic Release experiment. Each of these three experiments tested for microbial existence and utilization of a substrate by examining the gases evolved from specific chemical reactions. Although the results of these experiments were inconclusive, they inferred that there are no traces of extant life on Mars. However, the experiments did not specifically look for indication of extinct life. Therefore, most of the exobiologic strategies and experiments suggested for the Mars Rover Sample Return Mission involve searching for signature of extinct life. The most significant biological signatures and chemical traces to detect include: isotopic and chemical signatures of metabolic activity, anomalous concentrations of certain metals, trace and microfossils, organically preserved materials, carbonates, nitrates, and evaporites.

Schwartz, D. E.↗
NASA NTRS1989

Mars Rover Sample Return Orbiter design concepts

The observational orbiter of the Mars Rover Sample Return mission will observe the (10x10 km) landing sites and provide data that will be used in the decision to commit the landing vehicles to a landing at a chosen site. To provide observational data from orbit at a surface resolution consistent with the hazard tolerance of the landing vehicles, the orbiter imaging subsystem must be capable of 0.25 meters resolution per picture element (pixel). The design of the imaging, pointing, and data subsystems capable of providing this capability has been completed in this study. The rationale for these requirements and the more detailed derived requirements affecting the spacecraft design are discussed.

Randolph, J. E.↗