Planetology
Planetology research in 1967, with data on planet atmospheres and origins, moon, meteorites, impact cratering, and metamorphism
French, B. M.↗
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Results for “Impact cratering”
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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The moon's surface.
Lunar surface structure and formation, discussing impact craters, interplanetary collisions, volcanic traces, lunar soil, etc
Opik, E. J.↗
Ablation and breakup of large meteoroids during atmospheric entry
Large meteoroids ablation and breakup mathematical model, estimating Mars atmosphere effectiveness as shield against surface impact craters production
Baldwin, B.↗
Physical chemistry of the Aouelloul glass
Physical chemistry of Aouelloul impact crater glass, suggesting meteoritic origin of tektites
Okeefe, J. A.↗
An overview of Apollo program of lunar exploration.
Five round trip manned landing missions to the moon have returned hundreds of kilograms of samples and millions of bits of information from the scientific stations emplaced there and from the subsatellites left in orbit. Hundreds of man years of scientific effort and thousands of pages of journal space have been devoted to investigation of the samples and other aspects of the lunar problem. Our understanding of the moon has increased proportionately. Definitive conclusions can now be reached: (1) that there is a lunar crust, how thick it is in at least one region, and what kinds of rocks most probably compose it; (2) that we understand the major chronology of lunar events; (3) that the moon was extensively differentiated by igneous processes early in its history; (4) that impact cratering is the dominant surface process on the moon; and (5) that the moon is an ideal place to study extraterrestrial particle fluxes.
Petrone, R. A.↗
Small scale analogs of the Cayley Formation and Descarts Mountains in impact associated deposits, part C
The exploration of the Cayley Formation and material of the Descartes Mountains and an understanding of the origin and evolution of these units were primary objectives of the Apollo 16 lunar mission. This section examines several areas associated with impact crater deposits that show small-scale features similar in morphology to the regional characteristics of the Cayley and Descartes units shown in the Apollo 16 photography.
Head, J. W.↗
An overview of geologic results from Mariner 9
A summary of Mariner 9 mission operations insofar as they affected acquisition of geologic data is reported. Selected results with a minimum of supporting evidence are presented to give the geologic highlights of the mission. Volcanic features, tectonic features, channels, polar features, eolian features, impact craters, and the geological history of Mars are outlined.
Masursky, H.↗
Nature and origin of layered deposits of the Martian polar regions.
Layered deposits in the polar regions of Mars may be formed from fine dust ultimately derived from the canyons and other eroded terrains of the equatorial regions. An analysis of dust deposition in the area of annual frost cover predicts the formation of vast featureless domed plateaus underlaid by layered deposits of dust. Television observations suggest that these plateaus once existed, but they have now been dissected and stripped from most of the area of annual frost cover. A possible explanation is that a major secular change has occurred in the erosional environment of the Martian polar regions. Estimates of depositional rates of dust under current atmospheric conditions place the time span represented by the accumulation of layered deposits at about 500 m.y. Because of erosion, the present surface appears very young and lacks any impact craters. The present rate of water ice accumulation in the area of perennial frost is comparable to that of dust, and thus it is suggested that large quantities of water ice may be trapped with dust beneath the perennial frost caps.
Cutts, J. A.↗
Pyramidal structures on Mars
Triangular and polygonal pyramid like structures have been observed on the Martian surface. Located in the east central portion of Elysium Quadrangle (MC-15), these features are visible on the Mariner 9 photographs. B frames MTVS 4205-3 DAS 07794853 and MTVS 4296-24 DAS 12985882. The structures cast triangular and polygonal shadows. Steep-sided volcanic cones and impact craters occur only a few kilometers away. The mean diameter of the triangular pyramidal structures at the base is approximately 3.0 km, and the mean diameter of the polygonal structures is approximately 6.0 km. The observed Martian structures tend to line up suggesting joint or fault control. However, they do not appear to be controlled by the visible faults. The structures appear to be either wind-faceted volcanic cones and blocks or solidified blocks which have been rotated in semiconsolidated lava.
Gipson, M., Jr.↗
A primer in lunar geology
Primary topics in lunar geology range from the evolution of the solar system to lunar photointerpretation, impact crater formation, and sampling to analyses on various Apollo lunar landing site geomorphologies.
Greeley, R.↗
Orientale multi-ringed basin interior and implications for the petrogenesis of lunar highland samples
The lunar Orientale basin is a 900 km diam circular topographic depression covering an area of over 700,000 sq km on the western limb of the moon. Three major rings surround the central Mare Orientale. Orientale basin structures are considered along with Orientale basin deposits and the sequence of formation of structures and deposits. It is found that the structures and facies are related in time and mode of origin to the formation of a major impact crater approximately 620 km in diam. The study suggests that the Orientale basin configuration is very nearly the same as its geometry at its time of formation. The formation of multiringed basins such as Orientale provides a mechanism for an instantaneous production of tremendous volumes of melted lunar crystal material.
Head, J. W.↗
Preliminary geologic terrain map of Mercury
A geologic terrain map of Mercury has been constructed by use of the photogeologic methods employed for the moon and Mars. The oldest and most widespread unit, intercrater plains, forms nearly level to rolling surfaces on which are superposed numerous secondary impact craters. This unit may represent a very old surface that predates the last heavy bombardment of the inner planets. The effects of this bombardment are recorded in a second widespread unit, heavily cratered terrain, consisting of closely spaced craters and basins from 30 km to several hundred kilometers in diameter. Units formed by excavation of the 1300-km-diameter Caloris basin are widespread on one hemisphere of the planet. The development of the Caloris basin was followed relatively quickly by emplacement of widespread plains materials, most of which are probably volcanic.
Trask, N. J.↗
Multiringed basins - Illustrated by Orientale and associated features
Geologic mapping and photographs of the Orientale multiring basin are studied as to origin, size, and nature and distribution of ejecta. Six facies of ejecta are observed around the Cordillera Mountains: concentric, radial, smooth plains, grooved, secondary impact craters, and fissured. Transport of these ejecta occurred by block gliding, landsliding, debris flow, and possibly by base surge, viscous flow, and ballistic ejection. The ejecta are mainly clastic types, but melts and annealed breccias are expected to be abundant. Mixing of ejecta and substrate materials must have occurred; compositions of the ejecta are probably zoned laterally and vertically.
Moore, H. J.↗
Orange material in the Sulpicius Gallus formation at the southwestern edge of Mare Serenitatis
Orange and red materials were observed and photographed in the dark mantle of the Sulpicius Gallus Formation on the southwestern rim of the Serenitatis basin. These materials occur only within the dark mantle that overlies old rilled mare and highland units and are absent on the younger mare unit in this area. Orange and red materials occur predominantly as halos, patches, or rays around fresh impact craters ranging in diameter from less than 50 to 250 m and in layers exposed at the base of the dark mantle deposit in the steep walls of a depression and a graben. Red material is present in the highland subsurface, possibly as dikes. We conclude that orange material, locally underlain by red material, occurs in the dark mantle to a depth of about 50 m as locally stratified but discontinuous pyroclastic deposits and that it may have been produced by multiple 'fire foundation' eruptions during the later stages of accumulation of the older mare basalt units.
Lucchitta, B. K.↗
Mars
The evolution and physical structure of Mars are discussed primarily on the basis of Mariner 9 observations. The Martian atmosphere, density, and iron abundance are compared with those of earth, and it is noted that the planet was probably formed in less than 100,000 years. Stages in Martian differentiation are described together with the atmospheric composition, condensation and dust clouds, and surface winds. The surface is shown to have a wide diversity of geological landforms resulting from a variety of processes, including meteoroid bombardment, volcanic and tectonic activity, sapping, the action of running water, and wind action. Described landforms include impact craters, volcanic plains and domes, shield volcanoes, sinuous channels and gullies apparently formed by running water, and the enormous canyon system. Mechanisms for climatic change are considered, and questions are posed regarding the possibility of life on Mars.
Pollack, J. B.↗
Planetary geology
The solar system is considered along with the significance of meteorites as samples of the universe, the origin of planets, and earth's-eye view of the moon, previews of the lunar surface, aspects of impact cratering, lunar igneous processes, the mapping of the moon, the exploration of the moon in connection with the Apollo lunar landings, and the scientific payoff from the lunar samples. Studies of Mars, Venus, and the planets beyond are discussed, taking into account the Mariner Mars program, the Mariner orbiting mission, missions to Venus, the Mariner flight to Mercury, and the Pioneer missions. Attention is also given to the origin of the moon, implications of the moon's thermal history, similarities and differences in planetary evolution, and the role of internal energy in planetary development.
Short, N. M.↗
Cosmic ray exposure ages of features and events at the Apollo landing sites
Cosmic-ray exposure ages of lunar samples have been used to date surface features related to impact cratering and downslope movement of material. Only when multiple samples related to a feature have the same rare-gas exposure age or when a single sample has the same Kr-81 -Kr and track-exposure age can a feature be considered as reliably dated. Based on these criteria, there are only five well-dated lunar features: Cone Crater (Apollo 14), 26 m.y,; North Ray Crater (Apollo 16), 50 m.y.; South Ray Crater (Apollo 16), 2 m.y.; the emplacement of the Station 6 boulders (Apollo 17), 22 m.y.; and the emplacement of the Station 7 boulder (Apollo 17), 28 m.y. Other features are tentatively dated or have limits set on their ages: Bench Crater (Apollo 12), upper limit of 99 m.y.; Baby Ray Crater (Apollo 16), upper limit of 2 m.y.; Shorty Crater (Apollo 17), approximately 30 m.y.; Camelot Crater (Apollo 17) upper limit of 140 m.y.; the emplacement of the Station 2 boulder 1 (Apollo 17), 45 to 55 m.y.; and the slide which generated the light mantle (Apollo 17), lower limit of 50 m.y.
Arvidson, R.↗
Micrometeorites and solar flare particles in and out of the ecliptic
Using crystals grown into vugs from oriented lunar rocks as directional detectors of cosmic dust particles and solar flare nuclei, I have measured the angular distribution of the flux of micrometeoroids of mass 30 attograms to 80 femtograms. Hypervelocity impact craters of diameter 500 A to 10 microns and tracks from solar flare nuclei of energy 100 keV/amu to 20 MeV/amu were observed in crystals from rock 71055 facing lunar south and in crystals from rock 74255 facing lunar east. I have found that dust grains both in ecliptic orbits and in orbits inclined to the ecliptic have virtually identical mass-frequency distributions and similar shapes. I have evaluated the micrometeoroid fluxes after determining the exposure ages of the individual vug crystals by measuring the solar flare track density gradients in each crystal. The flux of particles of mass greater than 4 femtograms confined to the ecliptic is in good agreement with satellite measurements, suggesting that the micrometeoroid flux has been relatively constant over the past 35,000 yr. The flux of particles producing microcraters on a lunar surface facing south is lower than the ecliptic flux by a factor of about 7.
Hutcheon, I. D.↗