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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

The composition and origin of the moon.

Many of the properties of the moon can be explained by early condensation processes in the solar nebula. Thermodynamic calculations show that Ca-, Al- and Ti-rich compounds condense first in a cooling nebula. The inital high-temperature mineralogy is gehlenite, spinel, perovskite, (Ca-Al)-rich pyroxenes and anorthite. Inclusions in type III carbonaceous chondrites such as the Allende meteorite are composed primarily of these minerals and are highly enriched in trace refractories such as REE relative to carbonaceous chondrites. These inclusions can yield basalt and anorthosite in the proportions required to eliminate the europium anomaly, leaving a residual spinel-melilite interior. A high-(Ca-Al) deep interior does not imply an unacceptable mean density of moment of inertia for the moon. The inferred high-U content of the lunar interior, both from the Allende analogy and the high heat flow, indicates a high-temperature interior. The model is consistent with extensive early melting, shallow melting at 3 AE, and with presently high deep internal temperatures.

Anderson, D. L.↗
NASA NTRS1974

Formation and composition of the moon

Many of the properties of the moon are discussed including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr and the REE and the depletion in Fe, Rb, K, Na and other volatiles which could be understood if the moon represents a high temperature condensate from the solar nebula. Thermodynamic calculations show that Ca, Al and Ti rich compounds condense first in a cooling nebula. The initial high temperature mineralogy is gehlenite, spinel, perovskite, Ca-Al-rich pyroxenes and anorthite. Inclusions in Type III carbonaceous chondrites such as the Allende meteorite are composed primarily of these minerals and, in addition, are highly enriched in refractories such as REE relative to carbonaceous chondrites. These inclusions can yield basalt and anorthosite in the proportions required to eliminate the europium anomaly, leaving a residual spinel-melilite interior.

Anderson, D. L.↗
NASA NTRS1977

Origin of earth's moon

The major geochemical properties of the moon are briefly considered along with the significant facts of the moon's geologic history, and then the three current hypotheses regarding the moon's origin, namely, fission, capture, and binary accretion, are reviewed. The individual merits and improbabilities associated with each mechanism are taken into consideration. Special attention is given to the binary accretion model as the most promising one. In the variants of this model, of crucial importance is the nature of the more general hypothesis assumed for planetary formation from the solar nebula. The two main models differ considerably in the amount of chemical fractionation they allow to accompany planetary formation.

Wood, J. A.↗
NASA NTRS1977

Formation and composition of the moon

Many of the properties of the Moon, including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr, and the REE and the depletion in Fe, Rb, K, Na, and other volatiles can be understood if the Moon represents a high-temperature condensate from the solar nebula. Thermodynamic calculations show that Ca-, Al-, and Ti-rich compounds condense first in a cooling nebula. The initial high temperature mineralogy is gehlenite, spinel, perovskite, Ca-Al-rich pyroxenes, and anorthite. Inclusions in carbonaceous chondrites such as the Allende meteorite are composed primarily of these minerals and, in addition, are highly enriched in refractories such as REE relative to carbonaceous chondrites. These inclusions can yield basalt and anorthosite in the proportions required to eliminate the europium anomaly, leaving a residual spinel-melilite interior. A deep interior high in Ca-Al does not imply an unacceptable mean density or moment of inertia for the Moon. The inferred high-U content of the lunar interior, both from the Allende analog and the high heat flow, indicates a high-temperature interior. The model is consistent with extensive early melting, with shallow melting at 3 AE, and with presently high deep internal temperatures. It is predicted that the outer 250 km is rich in plagioclase and FeO. The low iron content of the interior in this model raises the interior temperatures estimated from electrical conductivity by some 800 C.

Anderson, D. L.↗
NASA NTRS1973

Optical properties of Apollo 12 moon samples.

We present the photometric phase function, color, normal albedo, polarimetric phase function, and spectrophotometry of the Apollo 12 soil. With a few minor exceptions, the optical properties of the Apollo 12 soil are very similar to those of the Apollo 11 soil and of lunar mare surfaces.

O'Leary, B.↗
NASA NTRS2020

Assessing the Roughness Properties of Circumpolar Lunar Craters: Implications for the Timing of Water-Ice Delivery to the Moon

The roughness properties of impact craters are valuable indicators of crater degradation and can provide insight into crater ages. We evaluate the roughness of lunar craters from different geologic eras, confirming that young, Copernican craters are distinctly rougher than older craters. We evaluate the potential age of small (less than similar to 15 km) craters that are thought to host surface ice by quantifying the roughness inside these craters, as well as outside. Interior roughness may be subdued by slope processes or the presence of volatiles. The distribution of ice-bearing craters is skewed toward roughness values higher than those of pre-Imbrian craters, although no ice-bearing craters are within the Copernican-only domain in roughness space. All of the 15 rough, permanently shadowed craters that are found within the Copernican-only domain lack water-ice detections, suggesting that either ice has not been delivered to these young craters or that it has since been destroyed.

Ariel N Deutsch↗
NASA NTRS1993

Theoretical studies of the radar properties of the icy Galilean moons of Jupiter

The icy Galilean satellites of Jupiter - Europa, Ganymede, and Callisto - have unusual radar scattering properties compared with those of the terrestrial planets or Earth's Moon. There are three main features of the data that distinguish these targets: (1) the radar cross-section normalized by the geometrical cross-section is an order of magnitude larger than that of any terrestrial planet; (2) the reflected power is almost evenly distributed between two orthogonal polarizations with more power being returned in the same circular polarization as was transmitted whereas virtually all of the power returned from the terrestrial planets is contained in the opposite circular polarization to the one that was transmitted; and (3) the echo power spectra have a broad shape indicating a nearly uniformly radar-bright surface in contrast to the spectra from the terrestrial planets that contain a strong quasi-specular component from the vicinity of the sub-radar point and very little reflected power from the rest of the surface. The normalized radar cross-sections decrease as the areal water ice coverage decreases from Europa to Ganymede to Callisto. Recently, radar echoes from the polar caps of Mars and Mercury, and from Saturn's satellite Titan imply similarly strong cross-sections and have classically unexpected polarization properties and it is also thought that this is due to the presence of ice on the surface. A model called the radar glory model is analyzed and it is shown that the main features of the radar echoes calculated from this model agree well with the observations from all three icy Galilean satellites. This model involves long radar paths in the ice below the surface and special structures in which the refractive index decreases abruptly at a hemispherical boundary. It is not known whether such structures exist or how they could be created, but possible scenarios can be imagined such as the formation of an impact crater followed by deposition of a frost layer followed by a resurfacing event in which a layer of solid ice is placed above the layer of frost. Regardless of the exact geophysical processes required to create such structures, the superior ability of this model to account for all of the important observations with very few adjustable parameters and with no ad hoc assumptions is a compelling argument in support of at least the electromagnetic model. The key features of the electromagnetic model are multiple subsurface scattering events, total internal reflection, and a low degree of randomness imposed on a deterministic geometry that strongly favors backscattering.

Eshleman, Von R.↗
NASA NTRS1997

Description and Analysis of Core Samples: The Lunar Experience

Although no samples yet have been returned from a comet, extensive experience from sampling another solar system body, the Moon, does exist. While, in overall structure, composition, and physical properties the Moon bears little resemblance to what is expected for a comet, sampling the Moon has provided some basic lessons in how to do things which may be equally applicable to cometary samples. In particular, an extensive series of core samples has been taken on the Moon, and coring is the best way to sample a comet in three dimensions. Data from cores taken at 24 Apollo collection stations and 3 Luna sites have been used to provide insight into the evolution of the lunar regolith. It is now well understood that this regolith is very complex and reflects gardening (stirring of grains by micrometeorites), erosion (from impacts and solar wind sputtering), maturation (exposure on the bare lunar surface to solar winds ions and micrometeorite impacts) and comminution of coarse grains into finer grains, blanket deposition of coarse-grained layers, and other processes. All of these processes have been documented in cores. While a cometary regolith should not be expected to parallel in detail the lunar regolith, it is possible that the upper part of a cometary regolith may include textural, mineralogical, and chemical features which reflect the original accretion of the comet, including a form of gardening. Differences in relative velocities and gravitational attraction no doubt made this accretionary gardening qualitatively much different than the lunar version. Furthermore, at least some comets, depending on their orbits, have been subjected to impacts of the uppermost surface by small projectiles at some time in their history. Consequently, a more recent post-accretional gardening may have occurred. Finally, for comets which approach the sun, large scale erosion may have occurred driven by gas loss. The uppermost material of these comets may reflect some of the features of this erosional process, such as crust formation, and variations with depth might be expected. Overall, the upper few meters of a comet may be as complex in their own way as the upper few meters of the lunar regolith have proven to be, and by analogy, detailed studies of core samples containing this depth information will be needed to understand these processes and the details of the accretional history and the subsequent alteration history of comets.

McKay, David S.↗
NASA NTRS1972

The moon as a high temperature condensate

The accretion during condensation mechanism is used to explain the differences in composition of the terrestrial planets and the moon. Many of the properties of the moon, including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr and the REE and the depletion in Fe, Rb, K, Na and other volatiles can be understood if the moon represents a high temperature condensate from the solar nebula. Thermodynamic calculations show that Ca, Al and Ti rich compounds condense first in a cooling nebula. The high temperature mineralogy is gehlenite, spinel perovskite, Ca-Al-rich pyroxenes and anorthite. The model is consistent with extensive early melting, shallow melting at 3 A.E. and with presently high speed internal temperatures. It is predicted that the outer 250 km is rich in plagioclase and FeO. The low iron content of the interior in this model raises the interior temperatures estimated from electrical conductivity by some 800 C. The lunar crust is 80 percent gabbroic anorthosite, 20 percent basalt and is about 250-270 km thick. The lunar mantle is probably composed of spinel, merwinite and diopside with a density of 3.4 g/cu cm.

Anderson, D. L.↗
NASA NTRS1976

Lunar Science Conference, 7th, Houston, Tex., March 15-19, 1976, Proceedings. Volume 1 - Regolith studies. Volume 2 - Petrogenetic studies of mare and highland rocks. Volume 3 - The moon and other bodies

Attention is given to lunar core studies (multi-core, deep drill, and drive tube), surface soil studies (petrography and geochemistry, light and volatile element studies, and agglutinate related studies), and surfaces process studies. Also considered are mare basalts, with emphasis on mineralogy and petrology, chemical and isotopic studies, and constraints and models of basalt evolution, along with breccia and highland samples with attention given to geochronology, boulders and consortium studies and the formation of highland samples. Remote sensing and photogeology of the moon, crustal bombardment, physical properties of the moon, and comparative planetology are also discussed.

Merrill, R. B.↗
NASA NTRS1991

Lunar sourcebook - A user's guide to the moon

The present status of lunar knowledge based on U.S. and USSR lunar missions and the continuing analysis of lunar samples and data is reviewed. Particular attention given to exploration, samples, and recent concepts of the moon; the lunar environment; lunar surface processes; the lunar minerals, rocks, and regolith; chemical elements in the moon; physical properties of the lunar surface; and global and regional data about the moon.

Heiken, Grant H.↗
NASA NTRS1978

Interpretation of ground-based microwave measurements of the moon using a detailed regolith properties model

A detailed model for the regolith's thermophysical and microwave properties has been used for the interpretation of ground-based measurements of the moon's microwave brightness temperature variation with lunar phase and changes during eclipses. The ground-based measurements include some crucial new lunation variation observations at 2.8, 6.0 and 13.1 cm. The many parameters in the regolith properties model were assigned values based on a careful review of Apollo in situ and lab sample measurements of thermophysical and electrical properties. The first identification of a wavelength-dependent component of scattering is reported.

Gary, B. L.↗