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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Mare volcanism and lunar crustal structure

It is pointed out that the concept of hydrostatic head, the height to which a fluid at a given pressure will rise in a gravitational field, can be usefully applied to magmatic liquids and to a number of problems in volcanology. For the moon, hydrostatic head arguments are an essential ingredient to explanations of mascons and of the scarcity of farside maria. In the reported investigation, simple hydrostatic concepts are extended to synthesize results from experimental petrology, lunar chronology, thermal history models, seismology, and gravity. Attention is given to a scenario for early lunar history, the density of lunar rocks and basaltic liquids, the thickness of the lunar crust, the source depth of mare basalt versus time, hydrostatic considerations with respect to the occurrence of high-titanium and low-titanium mare basalts, the structure of mascons, and the extension of the concepts of hydrostatics to the parent liquids of other basaltic rocks returned from the lunar surface.

Solomon, S. C.↗
NASA NTRS2012

Gravity Recovery and Interior Laboratory (GRAIL) Mission: Mission Status and Initial Science Results

The Gravity Recovery and Interior Laboratory (GRAIL) Mission is a component of the NASA Discovery Program. GRAIL is a twin-spacecraft lunar gravity mission that has two primary objectives: to determine the structure of the lunar interior, from crust to core; and to advance understanding of the thermal evolution of the Moon. GRAIL launched successfully from the Cape Canaveral Air Force Station on September 10, 2011, executed a low-energy trajectory to the Moon, and inserted the twin spacecraft into lunar orbit on December 31, 2011 and January 1, 2012. A series of maneuvers brought both spacecraft into low-altitude (55-km), near-circular, polar lunar orbits, from which they perform high-precision satellite-to-satellite ranging using a Ka-band payload along with an S-band link for time synchronization. Precise measurements of distance changes between the spacecraft are used to map the lunar gravity field. GRAIL completed its primary mapping mission on May 29, 2012, collecting and transmitting to Earth >99.99% of the possible data. Spacecraft and instrument performance were nominal and has led to the production of a high-resolution and high-accuracy global gravity field, improved over all previous models by two orders of magnitude on the nearside and nearly three orders of magnitude over the farside. The field is being used to understand the thickness, density and porosity of the lunar crust, the mechanics of formation and compensation states of lunar impact basins, and the structure of the mantle and core. GRAIL s three month-long-extended mission will initiate on August 30, 2012 and will consist of global gravity field mapping from an average altitude of 22 km.

Neumann, Gregory A.↗
NASA NTRS1993

A High Resolution Lunar Gravity Field and Predicted Orbit Behavior

This data set provides global gravity coverage directly for the nearside and indirectly for the farside. The gravity field will be evaluated by comparing resolution of surface fearture with prevoius existing gravity fields such as the field determined ty Bills and Ferrari (1980) and also by prediction of the Apollo 16 subsatellite crash.

Lunar↗
NASA NTRS1997

The Phanerozoic Impact Cratering Rate: Evidence from the Farside of the Moon

The relatively recent (< 1 b.y.) flux of asteroids and comets forming large craters on the Earth and Moon may be accurately recorded by craters with bright rays on the Moon's farside. Many previously unknown farside rayed craters are clearly distinguished in the low-phase-angle images returned by the Clementine spacecraft. Some large rayed craters on the lunar nearside are probably significantly older than 1 Ga; rays remain visible over the maria due to compositional contrasts long after soils have reached optical maturity. Most of the farside crust has a more homogeneous composition and only immature rays are visible. The size-frequency distribution of farside rayed craters is similar to that measured for Eratosthenian craters (up to 3.2 b.y.) at diameters larger than 15 km. The areal density of farside rayed craters matches that of a corrected tabulation of nearside Copernican craters. Hence the presence of bright rays due to immature soils around large craters provides a consistent time-stratigraphic basis for defining the base of the Copernican System. The density of large craters less than approximately 3.2 b.y. old is approximately 3.2 times higher than that of large farside rayed craters alone. This observation can be interpreted in two ways: (1) the average cratering rate has been constant over the past 3.2 b.y. and the base of the Copernican is approximately 1 Ga, or (2) the cratering rate has increased in recent geologic time and the base of the Copernican is less than 1 Ga. We favor the latter interpretation because the rays of Copernicus (800-850 m.y. old) appear to be very close to optical maturity, suggesting that the average Copernican cratering rate was approximately 35% higher than the average Eratosthenian rate. Other lines of evidence for an increase in the Phanerozoic (545 Ga) cratering rate are (1) the densities of small craters superimposed on Copernicus and Apollo landing sites, (2) the rates estimated from well-dated terrestrial craters (< 120 m.y.) and from present-day astronomical observations, and (3) the Proterozoic rate suggested by the crater record of Australia. The hypothesis most consistent with several key observations is that the cratering rate has increased by approximately 2x during the past approximately 300 m.y..

McEwen, Alfred S.↗
DOE OSTI2024

Design and Characterization of the Engineering Model of the Spectrometer Onboard LuSEE‐Night

Abstract The Lunar Surface Electromagnetics Explorer—Night, LuSEE‐Night, is a low‐frequency radio astronomy experiment that will explore the cosmic Dark Ages signal on the radio‐quiet farside of the Moon. The LuSEE‐Night carries a radio frequency spectrometer consisting of a set of antennas, analog and digital processing electronics, and will be launched by NASA's Commercial Lunar Payload Services in 2025. The spectrometer is designed to observe the spectrum of the radio sky in the 0.5−50 MHz band. The engineering model (EM) of the four‐channel spectrometer has been developed. The EM has been characterized for linearity, gain, noise, and their temperature dependence, confirming that the EM meets all the requirements for LuSEE‐Night. Three mitigation techniques have been implemented and verified to suppress self‐induced electromagnetic interference. The flight model of the spectrometer is currently being developed and is scheduled to be shipped to the integration site in early 2024.

Tamura, Emi↗
NASA NTRS1997

Topography of the Moon from the Clementine Lidar

Range measurements from the lidar instrument carried aboard the Clementine spacecraft have been used to produce an accurate global topographic model of the Moon. This paper discusses the function of the lidar; the acquisition, processing, and filtering of observations to produce a global topographic model; and the determination of parameters that define the fundamental shape of the Moon. Our topographic model: a 72nd degree and order spherical harmonic expansion of lunar radii, is designated Goddard Lunar Topography Model 2 (GLTM 2). This topographic field has an absolute vertical accuracy of approximately 100 m and a spatial resolution of 2.5 deg. The field shows that the Moon can be described as a sphere with maximum positive and negative deviations of approx. 8 km, both occurring on the farside, in the areas of the Korolev and South Pole-Aitken (S.P.-Aitken) basins. The amplitude spectrum of the topography shows more power at longer wavelengths as compared to previous models, owing to more complete sampling of the surface, particularly the farside. A comparison of elevations derived from the Clementine lidar to control point elevations from the Apollo laser altimeters indicates that measured relative topographic heights generally agree to within approx. 200 in over the maria. While the major axis of the lunar gravity field is aligned in the Earth-Moon direction, the major axis of topography is displaced from this line by approximately 10 deg to the cast and intersects the farside 24 deg north of the equator. The magnitude of impact basin topography is greater than the lunar flattening (approx. 2 km) and equatorial ellipticity (approx. 800 m), which imposes a significant challenge to interpreting the lunar figure. The floors of mare basins are shown to lie close to an equipotential surface, while the floors of unflooded large basins, except for S.P.-Aitken, lie above this equipotential. The radii of basin floors are thus consistent with a hydrostatic mechanism for the absence of significant farside maria except for S.P.-Aitken, whose depth and lack of mare require significant internal compositional and/or thermal heterogeneity. A macroscale surface roughness map shows that roughness at length scales of 10(exp 1) - 10(exp 2) km correlates with elevation and surface age.

Smith, David E.↗
NASA NTRS1991

Discovery and characterization of lunar materials: An incomplete process

Our knowledge of lunar materials is based on (1) sample collections (by the Apollo and Lunar missions, supplemented by Antarctic lunar meteorites); and (2) remote sensing (Earth-based or by spacecraft). The characterization of lunar materials is limited by the small number of sampled sites and the incomplete remote-sensing database (geochemical data collected from orbit cover 20 percent of the lunar surface). There is much about lunar surface materials that remains to be discovered. Listed are some features suspected form present knowledge: (1) Polar Materials; (2) Farside Materials; (3) Crater-Floor Materials; (4) Crater-Wall and Central Peak Materials; (5) Volcanic Shield and Dome Materials; (6) Transient-Event Materials; and (7) Meteoritic and Cometary Materials; This short list of likely discoveries isn't exhaustive. We know much about a few spots on the Moon, but little about the full range of lunar materials.

Vaniman, D.↗
DOE OSTI2023

Design and Characterization of the Engineering Model of the Spectrometer Onboard LuSEE-Night

The Lunar Surface Electromagnetics Explorer - Night, LuSEE-Night, is a low-frequency radio astronomy experiment that will explore the cosmic Dark Ages signal on the radio quiet farside of the Moon. The LuSEE-Night carries a radio frequency spectrometer consisting of a set of antennas, analog and digital processing electronics, and will be launched by NASA's Commercial Lunar Payload Services in 2025. The spectrometer is designed to observe the spectrum of the radio sky in the 0.5−50MHz band. The engineering model (EM) of the four-channel spectrometer has been developed. The EM has been characterized for linearity, gain, noise, and their temperature dependence, confirming that the EM meets all the requirements for LuSEE-Night. Three mitigation techniques have been implemented and verified to suppress self-induced electromagnetic interference (EMI). The flight model of the spectrometer is currently being developed and is scheduled to be shipped to the integration site in early 2024

47 OTHER INSTRUMENTATION↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Lunar Remote Sensing: Seeing the Big Picture

The session "Lunar Remote Sensing: Seeing the Big Picture" contained the following reports:Approaches for Approximating Topography in High Resolution, Multispectral Data; Verification of Quality and Compatibility for the Newly Calibrated Clementine NIR Data Set; Near Infrared Spectral Properties of Selected Nearside and Farside Sites ; Global Comparisons of Mare Volcanism from Clementine Near-Infrared Data; Testing the Relation Between UVVIS Color and TiO2 Composition in the Lunar Maria; Color Reflectance Trends in the Mare: Implications for Mapping Iron with Multispectral Images ; The Composition of the Lunar Megaregolith: Some Initial Results from Global Mapping; Global Images of Mg-Number Derived from Clementine Data; The Origin of Lunar Crater Rays; Properties of Lunar Crater Ejecta from New 70-cm Radar Observations ; Permanent Sunlight at the Lunar North Pole; and ESA s SMART-1 Mission to the Moon: Goals, Status and First Results.

Source record↗
NASA NTRS1972

Apollo 15 Index of 70 mm Photographs

All Apollo 15 70 mm photographs to which NASA photo numbers have been assigned are described in this index. In the first section all photographs are listed in sequence by NASA photo numbers. In subsequent sections, lunar surface and lunar orbital photographs are cross-indexed. Lunar surface photographs are listed in chronological order within the following categories: SEVA and LM window photos (LM window photos were taken before, between, and after EVA's), EVA 1, EVA 2, and EVA 3. Photographs of the lunar surface taken while in lunar orbit are cross-indexed by longitude in 10 deg increments, starting with the easternmost (farside) photos, and progressing to the westernmost (nearside) photos. Within each 10 deg interval of longitude, photographs are listed sequentially by NASA photo number, not by specific longitude of the principal point of each photograph.

Source record↗
NASA NTRS2010

The Use of Deep Moonquakes for Constraining the Internal Structure of the Moon

The installation of seismometers on the Moon s surface during the Apollo era provided a wealth of information that transformed our understanding of lunar formation and evolution. Seismic events detected by the nearside network were used to constrain the structure of the Moon s crust and mantle down to a depth of about 1000 km. The presence of an attenuating region in the deepest interior has been inferred from the paucity of farside events, as well as other indirect geophysical measurements. Recent re-analyses of the Apollo data have tentatively identified this region as a lunar core, although its properties are not yet constrained. Here we present new modeling in support of seismic missions that plan to build upon the knowledge of the Moon s interior gathered by Apollo. We have devised a method in which individual events can be linked to a known cluster using the observed S-P arrival time differences and azimuth to only two stations. Events can be further identified using each cluster's unique occurrence time signature

Weber, Renee↗
NASA NTRS1993

Preliminary results from Mariner 10: High resolution images of the Moon

In November of 1973 the Mariner 10 spacecraft acquired high resolution images of both the Earth and the Moon as it began its voyage to Venus and then Mercury. The best images had a resolution of approximately l km and were taken from an unusual viewpoint, above the lunar North Pole. At this time the Moon was illuminated such that the eastern limb, including approximately 30 degrees of the farside, was visible. Two high resolution mosaics were acquired during this period which provide excellent views of regions of the Moon poorly seen from the Earth. These include the Frigoris, Humboldtianum, Marginis, and Smythii regions. These images also covered expanses of highlands not visible from the Earth. These data were unique in that they were the only useful robotic spacecraft images of the Moon; and they remained so until December of 1990 when the Galileo spacecraft made its first encounter with the Moon. These Mariner 10 lunar images were acquired and are currently being used in conjunction with Earth-based telescopic spectra as well as Apollo and Lunar Orbiter photographic data to investigate the nature of deposits comprising the Northeast Nearside of the Moon. These Mariner 10 frames have proved useful for photogeologic, photometric, and photoclinometric analyses; they were also used in support of the second Galileo lunar encounter of December 1992.

Robinson, Mark S.↗
NASA NTRS1976

Lunar cartography with the Apollo 17 ALSE radar imagery

Lunar position differences between thirteen craters in Mare Serenitatis were computed from VHF radar-imagery obtained by the Lunar Sounder instrument flown on the Apollo 17 command module. The radar-derived position differences agree with those obtained by conventional photogrammetric reductions of Apollo metric photography. This demonstrates the feasibility of using the Apollo Lunar Sounder data to determine the positions of lunar features along the Apollo 17 orbital tracks. This will be particularly useful for western limb and farside areas, where no Apollo metric camera pictures are available.

Tiernan, M.↗
NASA NTRS1977

The Lunar Orbiter program

The Luna and Zond series of unmanned U.S.S.R. spacecraft were designed to investigate the moon and its vicinity. Sixteen Luna spacecraft and, six Zond spacecraft have obtained lunar data. These series have included flyby, lunar-orbiting, and soft-landing missions. A variety of experiments were carried out by these spacecraft including studies of magnetism, X-ray and gamma emissions, gravitational anomalies, and chemical composition. Soil samples, near- and farside photography (both color and black and white), and earth-cloud photography were also acquired. Luna 17 and 23, carried automatic roving vehicles (Lunokhod 1 and 2) that traversed portions of the lunar surface. Lunokhod 1 roamed in Mare Imbrium near Sinus Iridum, and Lunokhod 2 roamed in the Crater Le Monnier at the eastern edge of Mare Serenitatis. The Luna 16, 20, and 24 missions soft-landed on the lunar surface, scooped up lunar material, and returned these samples to earth. The photographic samples received are in the form of paper prints. Some publications containing photographs are described.

Source record↗
NASA NTRS2013

Basin Excavation, Lower Crust, Composition, and Bulk Moon Mass balance in Light of a Thin Crust

New lunar gravity results from GRAIL have been interpreted to reflect an overall thin and low-density lunar crust. Accordingly, crustal thickness has been modeled as ranging from 0 to 60 km, with thinnest crust at the locations of Crisium and Moscoviense basins and thickest crust in the central farside highlands. The thin crust has cosmochemical significance, namely in terms of implications for the Moon s bulk composition, especially refractory lithophile elements that are strongly concentrated in the crust. Wieczorek et al. concluded that the bulk Moon need not be enriched compared to Earth in refractory lithophile elements such as Al. Less Al in the crust means less Al has been extracted from the mantle, permitting relatively low bulk lunar mantle Al contents and low pre- and post-crust-extraction values for the mantle (or the upper mantle if only the upper mantle underwent LMO melting). Simple mass-balance calculations using the method of [4] suggests that the same conclusion might hold for Th and the entire suite of refractory lithophile elements that are incompatible in olivine and pyroxene, including the KREEP elements, that are likewise concentrated in the crust.

Jolliff, B. L.↗
NASA NTRS1974

Apollo laser altimetry and inferences as to lunar structure

Weighted mean laser altimetry data from Apollo 15, 16, and 17 tracks were analyzed, yielding a mean lunar radius of 1737.7 km and an offset of center-of mass from center of figure of 2.55 km toward 24 deg E. Weighted mean elevations with respect to a 1738 km radius sphere for various terrain types are: (1) farside terrae +1.8 km, (2) nearside terrae -1.4 km, (3) ringed maria -4.0 km, and (4) other maria -2.3 km. Comparison of gravity and topography data indicates that there is a variation in density in the outer parts of the moon and that the moon has a crust which is equivalent to at least 60 km of material of 2.95 grams per cu cm density. This result and moment-of-inertia data are consistent with a lunar interior model with a uniform density gradient in the mantle to the bottom of the lithosphere, constant density in the asthenosphere, and no core.

Kaula, W. M.↗
NASA NTRS1996

The Lunar Crust: Global Structure and Signature of Major Basins

New lunar gravity and topography data from the Clementine Mission provide a global Bouguer anomaly map corrected for the gravitational attraction of mare fill in mascon basins. Most of the gravity signal remaining after corrections for the attraction of topography and mare fill can be attributed to variations in depth to the lunar Moho and therefore crustal thickness. The large range of global crustal thickness (approx. 20-120 km) is indicative of major spatial variations in melting of the lunar exterior and/or significant impact-related redistribution. The 6l-km average crustal thickness, constrained by a depth-to-Moho measured during the Apollo 12 and 14 missions, is preferentially distributed toward the farside, accounting for much of the offset in center-of-figure from the center-of-mass. While the average farside thickness is 12 km greater than the nearside, the distribution is nonuniform, with dramatic thinning beneath the farside, South Pole-Aitken basin. With the global crustal thickness map as a constraint, regional inversions of gravity and topography resolve the crustal structure of major mascon basins to half wavelengths of 150 km. In order to yield crustal thickness maps with the maximum horizontal resolution permitted by the data, the downward continuation of the Bouguer gravity is stabilized by a three- dimensional, minimum-slope and curvature algorithm. Both mare and non-mare basins are characterized by a central upwarped moho that is surrounded by rings of thickened crust lying mainly within the basin rims. The inferred relief at this density interface suggests a deep structural component to the surficial features of multiring lunar impact basins. For large (greater than 300 km diameter) basins, moho relief appears uncorrelated with diameter, but is negatively correlated with basin age. In several cases, it appears that the multiring structures were out of isostatic equilibrium prior to mare emplacement, suggesting that the lithosphere was strong enough to maintain their state of stress to the present.

Neumann, Gregory A.↗
NASA NTRS1992

Lunar Resources Using Moderate Spectral Resolution Visible and Near-infrared Spectroscopy: Al/si and Soil Maturity

Modern visible and near-infrared detectors are critically important for the accurate identification and relative abundance measurement of lunar minerals; however, even a very small number of well-placed visible and near-infrared bandpass channels provide a significant amount of general information about crucial lunar resources. The Galileo Solid State Imaging system (SSI) multispectral data are an important example of this. Al/Si and soil maturity will be discussed as examples of significant general lunar resource information that can be gleaned from moderate spectral resolution visible and near-infrared data with relative ease. Because quantitative-albedo data are necessary for these kinds of analyses, data such as those obtained by Galileo SSI are critical. SSI obtained synoptic digital multispectral image data for both the nearside and farside of the Moon during the first Galileo Earth-Moon encounter in December 1990. The data consist of images through seven filters with bandpasses ranging from 0.40 microns in the ultraviolet to 0.99 microns in the near-infrared. Although these data are of moderate spectral resolution, they still provide information for the following lunar resources: (1) titanium content of mature mare soils based upon the 0.40/0.56-micron (UV/VIS) ratio; (2) mafic mineral abundance based upon the 0.76/0.99-micron ratio; and (3) the maturity or exposure age of the soils based upon the 0.56-0.76-micron continuum and the 0.76/0.99-micron ratio. Within constraints, these moderate spectral resolution visible and near-infrared reflectance data can also provide elemental information such as Al/Si for mature highland soils.

Fischer, Erich M.↗