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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Wind erosion in the Martian polar regions

Photographic evidence suggests that many topographic features of the polar regions of Mars may have been sculptured by wind action. In the case of the pitted terrain, this is established by relating the orientations of elongate basins and grooves to patterns of albedo markings that are generally accepted to be wind-formed. Small-scale flutes and other textures of laminated terrain recognized outside the perennial ice cap in the south polar region are also attributed to eolian action. Winds flowing off the polar cap and spiraling toward the west seem to be responsible. More speculatively the large-scale circumpolar features which underlie the residual polar caps may be related to wind erosion. Rotational motion localized on circular segments of the perennial frost deposits are proposed as a mechanism.

Cutts, J. A.↗
NASA NTRS1973

Mars: South polar pits and etched terrain

Martian south polar pits and etched terrain attest to alternating episodes of eolian deposition and erosion. Sometimes the south polar area has served as a sump for the accumulation of airborne debris and associated particles of frozen volatiles. At other times, the wind patterns or wind effectiveness change, and the atmosphere begins to remove the blanket of material it has earlier spread over the south polar region.

Sharp, R. P.↗
NASA NTRS1972

Preliminary Mariner 9 report on the geology of Mars.

Mariner 9 results indicate that Mars is geologically far more heterogeneous than previously suspected from earlier flyby missions; the surface has been shaped by volcanic, tectonic, erosional, and depositional activity. The equatorial region between 30 deg N and 30 deg S latitude is depicted in four geologic sketch maps, and seventeen geologic units are defined on the basis of their textural characteristics. The maps and the brief descriptions of geological units portrayed are followed by a series of more interpretive discussions dealing with topical problems and a summary geologic history. Topics covered include cratering, circular basins, volcanism, canyons, chaotic terrain, channels, and eolian activity.

Mccauley, J. F.↗
NASA NTRS1973

A generalized geologic map of Mars.

A geologic map of Mars has been constructed largely on the basis of photographic evidence. Four classes of units are recognized: (1) primitive cratered terrain, (2) sparsely cratered volcanic eolian plains, (3) circular radially symmetric volcanic constructs such as shield volcanoes, domes, and craters, and (4) tectonic erosional units such as chaotic and channel deposits. Grabens are the main structural features; compressional and strike slip features are almost completely absent. Most grabens are part of a set radial to the main volcanic area, Tharsis.

Carr, M. H.↗
NASA NTRS1973

Latitudinal distribution of a debris mantle on the Martian surface.

Mariner 9 narrow angle pictures show that many areas on Mars are buried by debris mantles that later have been partially eroded. A survey of the present debris distributions shows that they are symmetrically disposed about the polar regions, extending poleward from the 30 N and 30 S latitudes. These blankets are inferred to represent eolian debris derived from circumpolar layered deposits; the process of equatorward redistribution of debris by wind action is probably still continuing.

Soderblom, L. A.↗
NASA NTRS1973

Mariner 9 observations of the surface of Mars in the north polar region.

During the Mariner 9 extended mission the recession of the north polar ice caps was monitored for 130 days. The edge of the cap displayed a peculiar polygonal outline during most of this period. Regional topographic control is suggested as the most likely cause of the polygonality. Whereas densely cratered terrain dominates the south polar region, moderately cratered plains underlie the polar deposits in the north polar region. The mottled cratered plains have been mantled by light deposits located in annular rings south of 70 N. The erosional boundaries between these deposits and the subjacent cratered plains are gradational, show no local topographic relief, and display a spiral serrated circumpolar pattern suggesting eolian erosion. Smooth plains and 'etch-pitted' plains underlie the central polar layered deposits in both polar regions. In addition, these plains have one other morphological variant in the north. Here they display a pattern of very coherent ripple-like waveforms varying in wavelength from several hundred meters to a few kilometers.

Soderblom, L. A.↗
NASA NTRS1973

Photogeologic mapping of Meridiani Sinus region from Mariner 6 and 7 imagery

Photogeologic mapping of Mariner photographs characterizes major stratigraphic units of the Martian equatorial region. The low resolution photomosaic ship across Meridiani Sinus Deucalionus Regio is divided into regional map units based on albedo and crater density. High resolution frames reveal map units defined by varying surface texture, crater densities, and degree of crater sharpness. Mariner photographs provide clear evidence of eolian action and channelization by fluid flow.

Dehon, R. A.↗
NASA NTRS1975

Particle motion in atmospheric boundary layers of Mars and Earth

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.

White, B. R.↗
NASA NTRS1975

The geology of Mars - A brief review of some recent results

Some Mariner 9 data on geologic provinces, volcanic processes, geophysical models, Eolian activity, surface water, and atmospheric composition on Mars are presented. Ways in which this data is expected to be augmented by the Viking mission are briefly reviewed. Information given in map form includes permanent ice, layered deposits, etched plains, volcanic constructs (shields, domes, or cones), volcanic plains, moderately cratered plains, cratered plains, hummocky terrain, channel deposit, undivided plains, and grooved terrain.

Mutch, T. A.↗
NASA NTRS1975

A size-frequency study of large Martian craters

The log normal frequency distribution law was used to analyze the crater population on the surface of Mars. Resulting data show possible evidence for the size frequency evolution of crater producing bodies. Some regions on Mars display excessive depletion of either large or small craters; the most likely causes of the depletion are considered. Apparently, eolian sedimentation has markedly altered the population of the small craters south of -30 deg latitude. The general effects of crater obliteration in the Southern Hemisphere appear to be confined to diameters of less than 20 km. A strong depletion of large craters in a large region just south of Deuteronilus Mensae, and in a small region centered at 35 deg latitude and 10 deg west longitude, may indicate locations of subsurface ice.

Woronow, A.↗
NASA NTRS1976

Albedo boundaries on Mars in 1972 - Results from Mariner 9

A map of 'albedo' boundaries (light and dark markings) on Mars was prepared from Mariner 9 images. After special digital processing, these pictures provide detailed locations of albedo boundaries, which is significant in interpreting recent eolian activity. Derivation of absolute albedo values from the spacecraft data was not attempted. The map correlates well with telescopic observations of Mars after the 1971 dust storm.

Batson, R. M.↗
NASA NTRS1976

Geological applications of Nimbus radiation data in Middle East

Plateaus of Eocene limestone and exposed limestone escarpments, in Egypt and Saudi Arabia respectively, were indicated by cool brightness temperatures T sub B (less than 240 to 265 K) by the Nimbus 5 electrically scanning microwave radiometer (ESMR) over a 2-year period. Nubian sandstone, desert eolian sand and igneous metamorphic rocks were differentiated from these limestone areas by warm T sub B values (more than 265 to 300 K). Cool T sub B values in the form of a V were found over broad areas of the Nile Valley and in the western desert of central Egypt. Similar cool T sub B values were shown over limestone-dolomitic hills of the interior Homocline and the Hadramawt plateau of Saudi Arabia. Nimbus 5 and 6 ESMR T sub B values selectively identified intermediate dense rock types (limestone versus sandstone/granite) in the Lake Nasser region whose thermal inertia ranged from 0.035 to 0.06 cal cm to minus 2 C sec 1/2 to minus one half.

Allison, L. J.↗
NASA NTRS1976

Surficial geology of Mars: A study in support of a penetrator mission to Mars

Physiographic and surficial cover information were combined into unified surficial geology maps (30 quadrangles and 1 synoptic map). The surface of Mars is heterogeneous and is modified by wind, water, volcanism, tectonism, mass wasting and other processes. Surficial mapping identifies areas modified by these processes on a regional basis. Viking I mission results indicate that, at least in the landing site area, the surficial mapping based on Mariner data is fairly accurate. This area was mapped as a lightly cratered plain with thin or discontinuous eolian sediment. Analysis of lander images indicates that this interpretation is very close to actual surface conditions. These initial results do not imply that all surficial units are mapped correctly, but they do increase confidence in estimates based on photogeologic interpretations of orbital pictures.

Spudis, P.↗
NASA NTRS1977

Geological applications of Nimbus radiation data in the Middle East

Large plateaus of Eocene limestone and exposed limestone escarpments, in Egypt and Saudi Arabia, respectively, were indicated by cool brightness temperatures recorded by the Nimbus-5 electrically scanning microwave radiometer (ESMR), over a 2-year period. Nubian sandstone, desert eolian sand, and igneous-metamorphic rock of the Pliocene, Miocene, Oligocene, and Cretaceous periods were differentiated from these limestone areas by warm T sub B values. These brightness temperature differences are a result of seasonal in-situ ground temperatures and differential emissivity of limestone and sand, sandstone and granite, whose dielectric constants are 6 to 8.9 and 2.9 and 4.2 to 5.3, respectively, at 19.35 GHz.

Allison, L. J.↗
NASA NTRS1977

Reports of planetary geology program, 1976 - 1977

One hundred seventeen investigations undertaken in the NASA Planetary Geology Program in 1976-1977 are reported in abstract form. Topics discussed include solar system formation; planetary interiors; planetary evolution; asteroids, comets and moons; cratering; volcanic, eolian, fluvial and mass wasting processes; volatiles and the Martian regolith; mapping; and instrument development and techniques. An author index is provided.

Arvidson, R.↗
NASA NTRS1976

Estimated grain saltation in a Martian atmosphere

Mariner 9 spacecraft images showing evidence of variable surface features and surface erosion resulting from atmospheric wind on Mars have caused a renewed interest in the eolian mechanics of saltating grains. To study this phenomenon, both experimental investigation in an atmospheric wind tunnel and numerical solutions of the equations of motion of a single grain under Martian surface conditions were conducted. The numerical solutions for earth were used and empirically adjusted to correlate with existing experimental data for Mars. These modified equations were then solved to estimate grain motion for Mars. These calculations show the importance of a lifting force on the grain to initiate motion in both earth and Mars calculations. Major findings include a comparison of earth and Mars grain trajectories that show Mars length scales to be longer and to fall with a higher terminal grain velocity. The grains in the Mars calculation also made a smaller collision angle with the surface on rebound.

White, B. R.↗
NASA NTRS1976

Martian crater depth/diameter relationships - Comparison with the moon and Mercury

New Martian topographic data from Mariner 9 ultraviolet spectrometer (UVS) profiles provide depth data for 139 Martian craters of all degrees of degradation, between the diameters of 15 and 201 km. The population of Martian craters, including morphologically fresh examples, is shallower than both lunar and Mercurian fresh crater populations. Because the surface gravities of Mercury and Mars are identical within 5%, these differences in fresh crater depths suggest that factors other than gravity may play important roles in determining initial crater depths (e.g., differences in impact velocity, substrate variations, and Martian atmospheric effects during the crater-forming event). Degraded Martian craters are, on the average, no shallower than lunar pre-Imbrian craters of similar sizes. If the early bombardment of Mars was as significant a degradational agent as it was on the moon, then major levels of crater degradation and crater shallowing on Mars were associated with this mechanism. Continued eolian infilling, although locally significant, may be a less significant cause of morphometric degradation of large old Martian craters.

Cintala, M. J.↗
NASA NTRS1978

A bibliography of planetary geology principal investigators and their associates, 1976-1978

This bibliography cites publications submitted by 484 principal investigators and their associates who were supported through NASA's Office of Space Sciences Planetary Geology Program. Subject classifications include: solar system formation, comets, and asteroids; planetary satellites, planetary interiors, geological and geochemical constraints on planetary evolution; impact crater studies, volcanism, eolian studies, fluvian studies, Mars geological mapping; Mercury geological mapping; planetary cartography; and instrument development and techniques. An author/editor index is provided.

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