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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Transport of dust to high northern latitudes in a Martian polar warming

The transport of dust in the Martian atmosphere into high northern latitudes as a result of a Martian polar-warming (and global-dust-storm) event was investigated using a simplified transport model in conjunction with a beta-plane dynamical model to simulate the transport of dust. Numerical experiments were performed to examine the influence of different warming dynamics and to assess the sensitivity of the transport to the initial dust distribution. Results indicate that substantial amounts of dust could be transported and deposited at high northern latitudes (extending to the pole) in a polar-warming event. The potential for the transport of water was also examined through simulations, with results indicating that large amounts of water could be transported to the north polar region in a warming, on the condition that substantial condensation and precipitation do not take place in the subpolar regions. However, the warmth of the Martian atmosphere during global dust storms makes the latter possible.

Barnes, Jeffrey R.↗
NASA NTRS1990

Computation of thermo-chemical nonequilibrium Martian atmospheric entry flows

The aerothermodynamics of a Martian atmospheric entry trajectory are studied. A chemical kinetics model for the CO2-N2 mixture found in the Martian atmosphere is implemented in a two-dimensional computational fluid dynamics method. The gas mixture is allowed to be in thermo-chemical nonequilibrium and to be composed of eight species characterized by two temperatures. The CO2 reaction model is validated by comparing computations to experimental results. Results for typical Martian entry conditions are presented and limitations of the current thermophysical model are discussed.

Candler, Graham V.↗
NASA NTRS1990

Active thermal control systems for lunar and Martian exploration

Several ATCS options including heat pumps, radiator shading devices, and single-phase flow loops were considered. The ATCS chosen for both lunar and Martian habitats consists of a heat pump integral with a nontoxic fluid acquisition and transport loop, and vertically oriented modular reflux-boiler radiators. The heat pump operates only during the lunar day. The lunar and Martian transfer vehicles have an internal single-phase water-acquisition loop and an external two-phase ammonia rejection system with rotating inflatable radiators. The lunar and Martian excursion vehicles incorporate internal single-phase water acquisition, which is connected via heat exchangers to external body-mounted single-phase radiators. A water evaporation system is used for the transfer vehicles during periods of high heating.

Ewert, Michael K.↗
NASA NTRS1990

Aerobraking for capture into Martian orbit

A summary is given of several studies into problems associated with aerobraking a manned vehicle into a Martian capture orbit. The problems investigated are the establishment of entry flight path angle windows that allow aerocapture; the determination of the sensitivity of the entry trajectory to initial flight path angle; the determination of the effect on aerocapture of the assumed Martian atmosphere model; and the determination of the effect of random atmosphere disturbances on adaptive guidance systems that may be used for aerocapture. As a result of investigating the above problem areas, entry windows were established for three different vehicle configurations. Sensitivities to changes in initial flight path angle were also obtained for these three configurations. One configuration was chosen to determine the effect of Martian atmospheric model changes and random variations of density within a specific atmospheric model. Of particular interest was the effect of random density variations on adaptive guidance techniques. The effect of entry velocity on the size of the entry window was also examined.

Suit, William T.↗
NASA NTRS1990

Autonomous Martian flying rover

A remotely programmable, autonomous flying rover is proposed to extensively survey the Martian surface environment. A Mach .3, solar powered, modified flying wing could cover roughly a 2000 mile range during Martian daylight hours. Multiple craft launched from an orbiting mother ship could provide near-global coverage. Each craft is envisioned to fly at about 1 km above the surface and measure atmospheric composition, pressure and temperature, map surface topography, and remotely penetrate the near subsurface looking for water (ice) and perhaps evidence of life. Data collected are relayed to Earth via the orbiting mother ship. Near surface guidance and control capability is an adaptation of current cruise missile technology. A solar powered aircraft designed to fly in the low temperature, low density, carbon dioxide Martian atmosphere near the surface appears feasible.

Source record↗
NASA NTRS1991

Ancient oceans and Martian paleohydrology

The global model of ocean formation on Mars is discussed. The studies of impact crater densities on certain Martian landforms show that late in Martian history there could have been coincident formation of: (1) glacial features in the Southern Hemisphere; (2) ponded water and related ice features in the northern plains; (3) fluvial runoff on Martian uplands; and (4) active ice-related mass-movement. This model of transient ocean formation ties these diverse observations together in a long-term cyclic scheme of global planetary operation.

Baker, Victor R.↗
NASA NTRS1990

An efficient and accurate technique to compute the absorption, emission, and transmission of radiation by the Martian atmosphere

CO2 comprises 95 pct. of the composition of the Martian atmosphere. However, the Martian atmosphere also has a high aerosol content. Dust particles vary from less than 0.2 to greater than 3.0. CO2 is an active absorber and emitter in near IR and IR wavelengths; the near IR absorption bands of CO2 provide significant heating of the atmosphere, and the 15 micron band provides rapid cooling. Including both CO2 and aerosol radiative transfer simultaneously in a model is difficult. Aerosol radiative transfer requires a multiple scattering code, while CO2 radiative transfer must deal with complex wavelength structure. As an alternative to the pure atmosphere treatment in most models which causes inaccuracies, a treatment was developed called the exponential sum or k distribution approximation. The chief advantage of the exponential sum approach is that the integration over k space of f(k) can be computed more quickly than the integration of k sub upsilon over frequency. The exponential sum approach is superior to the photon path distribution and emissivity techniques for dusty conditions. This study was the first application of the exponential sum approach to Martian conditions.

Lindner, Bernhard Lee↗
NASA NTRS1990

Chemical evolution of the early Martian hydrosphere

The chemical evolution of the early Martian hydrosphere is discussed. The early Martian ocean can be modeled as a body of relatively pure water in equilibrium with a dense carbon dioxide atmosphere. The chemical weathering of lavas, pyroclastic deposits, and impact melt sheets would have the effect of neutralizing the acidity of the juvenile water. As calcium and other cations are added to the water by chemical weathering, they are quickly removed by the precipitation of calcium carbonate and other minerals, forming a deposit of limestone beneath the surface of the ocean. As the atmospheric carbon dioxide pressure and the temperature decrease, the Martian ocean would be completely frozen. Given the scenario for the chemical evolution of the northern lowland plains of Mars, it should be possible to draw a few conclusions about the expected mineralogy and geomorphology of this regions.

Schaefer, M. W.↗
NASA NTRS1991

Compression of Martian atmosphere for production of oxygen

The compression of CO2 from the Martian atmosphere for production of O2 via an electrochemical cell is addressed. Design specifications call for an oxygen production rate of 10 kg per day and for compression of 50 times that mass of CO2. Those specifications require a compression rate of over 770 cfm at standard Martian temperature and pressure (SMTP). Much of the CO2 being compressed represents waste, unless it can be recycled. Recycling can reduce the volume of gas that must be compressed to 40 cfm at SMTP. That volume reduction represents significant mass savings in the compressor, heating equipment, filters, and energy source. Successful recycle of the gas requires separation of CO (produced in the electrochemical cell) from CO2, N2, and Ar found in the Martian atmosphere. That aspect was the focus of this work.

Lynch, D. C.↗
NASA NTRS1991

Magnetic and electrical properties of Martian particles

The only determinations of the magnetic properties of Martian materials come from experiments on the two Viking Landers. The results suggest Martian soil containing 1 to 10 percent of a highly magnetic phase. Though the magnetic phase mineral was not conclusively identified, the predominate interpretation is that the magnetic phase is probably maghemite. The electrical properties of the surface of Mars were only measured remotely by observations with Earth based radar, microwave radiometry, and inference from radio-occultation of Mars orbiting spacecraft. No direct measurements of electrical properties on Martian materials have been performed.

Olhoeft, G. R.↗
NASA NTRS1991

Martian regolith as space radiation shielding

Mars exploration crews will be exposed to such high radiation dosages in route from earth that as to sharply reduce the allowable dose they should receive while on the Martian surface. An account is presently given of the possibility of using Martian regolith as crew shielding to maintain very low short-term dose limits. NASA-Langley's nucleon and heavy-ion transport computer codes are used to predict the propagation and interaction of the free-space nucleons and heavy ions through the Martian atmosphere and then through various thicknesses of regolith. The largest reduction in dose occurs in the first 15-20 cm of regolith material.

Simonsen, L. C.↗
NASA NTRS1991

Effect of particle size of Martian dust on the degradation of photovoltaic cell performance

Glass coverglass and SiO2 covered and uncovered silicon photovoltaic (PV) cells were subjected to conditions simulating a Mars dust storm, using the Martian Surface Wind Tunnel, to assess the effect of particle size on the performance of PV cells in the Martian environment. The dust used was an artificial mineral of the approximate elemental composition of Martian soil, which was sorted into four different size ranges. Samples were tested both initially clean and initially dusted. The samples were exposed to clear and dust laden winds, wind velocities varying from 23 to 116 m/s, and attack angles from 0 to 90 deg. It was found that transmittance through the coverglass approximates the power produced by a dusty PV cell. Occultation by the dust was found to dominate the performance degradation for wind velocities below 50 m/s, whereas abrasion dominates the degradation at wind velocities above 85 m/s. Occultation is most severe at 0 deg (parallel to the wind), is less pronounced from 22.5 to 67.5 deg, and is somewhat larger at 90 deg (perpendicular to the wind). Abrasion is negligible at 0 deg, and increases to a maximum at 90 deg. Occultation is more of a problem with small particles, whereas large particles (unless they are agglomerates) cause more abrasion.

Gaier, James R.↗
NASA NTRS1991

Degradation studies of Martian impact craters

The amount of obliteration suffered by Martian impact craters is quantified by comparing measurable attributes of the current crater shape to those values expected for a fresh crater of identical size. Crater diameters are measured from profiles obtained using photoclinometry across the structure. The relationship between the diameter of a fresh crater and a crater depth, floor width, rim height, central peak height, etc. was determined by empirical studies performed on fresh Martian impact craters. We utilized the changes in crater depth and rim height to judge the degree of obliteration suffered by Martian impact craters.

Barlow, N. G.↗
NASA NTRS1992

Oxygen in the Martian atmosphere: Regulation of PO2 by the deposition of iron formations on Mars

During Earth's early history, and prior to the evolution of its present day oxygenated atmosphere, extensive iron rich siliceous sedimentary rocks were deposited, consisting of alternating layers of silica (chert) and iron oxide minerals (hematite and magnetite). The banding in iron formations recorded changes of atmosphere-hydrosphere interactions near sea level in the ancient ocean, which induced the oxidation of dissolved ferrous iron, precipitation of insoluble ferric oxides and silica, and regulation of oxygen in Earth's early atmosphere. Similarities between the Archean Earth and the composition of the present day atmosphere on Mars, together with the pervasive presence of ferric oxides in the Martian regolith suggest that iron formation might also have been deposited on Mars and influenced the oxygen content of the Martian atmosphere. Such a possibility is discussed here with a view to assessing whether the oxygen content of the Martian atmosphere has been regulated by the chemical precipitation of iron formations on Mars.

Burns, Roger G.↗
NASA NTRS1992

The composition of Martian aeolian sands: Thermal emissivity from Viking IRTM observations

Aeolian sands provide excellent surfaces for the remote determination of the mineralogic composition of Martian materials, because such deposits consist of relatively well-sorted, uniform particle sizes and might consist of chemically unaltered, primary mineral grains derived from bedrock. Dark features on the floors of Martian craters are controlled by aeolian processes and many consist largely of unconsolidated, windblown sand. Measurement of the thermal emissivity of geologic materials provides a way to identify mid-infrared absorption bands, the strength and positions of which vary with mineral structure and composition. The Viking Infrared Thermal Mapper (IRTM) had four surface-sensing mid-IR bands, three of which, the 7, 9, and 11 micron channels, correspond to absorption features characteristic of carbonates, sialic, and mafic minerals, respectively. In this study, the highest quality IRTM data were constrained so as to avoid the effects of atmospheric dust, clouds, surface frosts, and particle size variations (the latter using data obtained between 7 and 9 H, and they were selected for dark intracrater features such that only data taken directly from the dark feature were used, so as to avoid thermal contributions from adjacent but unrelated materials. Three-point emissivity spectra of Martian dart intracrater features were compared with laboratory emission spectra of minerals and terrestrial aeolian sands convolved using the IRTM response function to the four IRTM spectral channels.

Edgett, Kenneth S.↗
NASA NTRS1993

A DTA/GC for the in Situ Identification of the Martian Surface Material

The composition and mineralogy of the Martian surface material remain largely unknown. To determine its composition and mineralogy, several techniques are being considered for in situ analyses of the Martian surface material during missions to Mars. We have successfully developed, constructed, and tested a laboratory DTA/GC. The DTA is a Dupont model 1600 high temperature DTA coupled with a GC equipped with a MID detector. The system is operated by a Sun Sparc 11 workstation. When gas evolves during a thermal chemical event, it is shunted into the GC and the temperature is recorded in association with the specific thermal event. We have used this laboratory instrument to define experimental criteria necessary for determining the composition and mineralogy of the Martian surface in situ (e.g., heating of sample to 1100 C to distinguish clays). Our studies indicate that DTA/GC will provide a broad spectrum of mineralogical and evolved gas data pertinent to exobiology, geochemistry, and geology.

Mancinelli, R. L.↗
NASA NTRS1993

Prototype Backscatter Moessbauer Spectrometer for Measurement of Martian Surface Mineralogy

We have designed and successfully tested a prototype of a backscatter Moessbauer spectrometer (BaMS) targeted for use on the Martian surface to (1) determine oxidation states of iron, and (2) identify and determine relative abundances of iron-bearing mineralogies. No sample preparation is required to perform measurements; it is only necessary to bring sample and instrument into physical contact. The prototype meets our projected specification for a flight instrument in terms of mass, power, and volume. A Moessbauer spectrometer on the Martian surface would provide wide variety of information about the current state of the Martian surface, and this information is described.

Shelfer, T. D.↗
NASA NTRS1991

The engineering of a nuclear thermal landing and ascent vehicle utilizing indigenous Martian propellant

The following paper reports on a design study of a novel space transportation concept known as a 'NIMF' (Nuclear rocket using Indigenous Martian Fuel). The NIMF is a ballistic vehicle which obtains its propellant out of the Martian air by compression and liquefaction of atmospheric CO2. This propellant is subsequently used to generate rocket thrust at a specific impulse of 264 s by being heated to high temperature (2800 K) gas in the NIMFs' nuclear thermal rocket engines. The vehicle is designed to provide surface to orbit and surface to surface transportation, as well as housing, for a crew of three astronauts. It is capable of refueling itself for a flight to its maximum orbit in less than 50 days. The ballistic NIMF has a mass of 44.7 tonnes and, with the assumed 2800 K propellant temperature, is capable of attaining highly energetic (250 km by 34,000 km elliptical) orbits. This allows it to rendezvous with interplanetary transfer vehicles which are only very loosely bound into orbit around Mars. If a propellant temperature of 2000 K is assumed, then low Mars orbit can be attained; while if 3100 K is assumed, then the ballistic NIMF is capable of injecting itself onto a minimum energy transfer orbit to Earth in a direct ascent from the Martian surface.

Zubrin, Robert M.↗