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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Lunar magnetic permeability studies and magnetometer sensitivity

A regression of quiet magnetic field components simultaneously measured by the two Explorer 35 magnetometers reveals uncertainties in effective sensitivity factors of up to a few percent in one or both of these instruments. Given this, the validity of previous lunar permeability studies based on Explorer 35/ALSEP regressions, wherein inferences are drawn from regression line slopes differing from unity by the order of one percent, is called into question. We emphasize the need to critically address the question of small deviations in magnetometer sensitivity factors from nominal values as a part of any two-magnetometer lunar permeability study.

King, J. H.↗
NASA NTRS1982

Orientation and origin of ridges in the Lunae Palus - Coprates region of Mars

By analogy with lunar mare ridges and from morphologic evidence, such as the smooth slopes of arches, the wrinkle ridges of the Tharsis region of Mars are interpreted to primarily result from compressional folding of the volcanic plains. Comparison of ridge orientations in the Lunae Palus and Coprates quadrangles to a Tharsis center indicates that more than 60% of the total length of ridges is orthogonal to a normal from this center. Graben trends in surrounding terrain indicate that nonorthogonal ridges are not significantly affected by regional scale structures. Comparison of orthogonal and nonorthogonal ridge frequencies suggests that loading due to the Tharsis plateau produced compressional features as far as 4000 km from the center of the load, and that additional compressional stress sources are needed to account for ridge systems at greater distances from the Tharsis plateau.

Maxwell, T. A.↗
NASA NTRS2003

New Ground-based Spectral Observations of Mercury and Comparison with the Moon

Spectroscopic observations (400-670 nm) of Mercury were made at La Palma with the Nordic Optical Telescope (NOT) in June and July of 2002. Extensive observations of solar analog standard stars and validation spectra of 7 Iris and a variety of locations on the Moon were also collected. The 2002 Mercury data were also combined with previous observations (520-970 nm) from the Swedish Solar Vacuum Telescope (SVST). A spectrum (400-970 nm) calibrated to standard bidirectional geometry (alpha=i=30deg, e=0deg) was constructed based on the spectral slopes from 2002. The combined spectrum permits analysis with the Lucey lunar abundance relations for FeO and TiO2.

Blewett, D. T.↗
NASA NTRS2011

Use of Hawaii Analog Sites for Lunar Science and In-Situ Resource Utilization

In-Situ Resource Utilization (ISRU) and lunar science share similar objectives with respect to analyzing and characterizing the physical, mineral, and volatile materials and resources at sites of robotic and human exploration. To help mature and stress instruments, technologies, and hardware and to evaluate operations and procedures, space agencies have utilized demonstrations at analog sites on Earth before use in future missions. The US National Aeronautics and Space Administration (NASA), the Canadian Space Agency (CSA), and the German Space Agency (DLR) have utilized an analog site on the slope of Mauna Kea on the Big Island of Hawaii to test ISRU and lunar science hardware and operations in two previously held analog field tests. NASA and CSA are currently planning on a 3rd analog field test to be held in June, 2012 in Hawaii that will expand upon the successes from the previous two field tests.

Sanders, G. B.↗
NASA NTRS1972

Abrasion and catastrophic rupture of lunar rocks - Some implications to the micrometeoroid flux at 1 AU.

Results from laboratory studies of hypervelocity impact against crystalline rocks, combined with estimates of the micrometeoroid flux at the lunar surface, provide a basis for calculating abrasion rates and survival times before catastrophic rupture of rocks on the lunar surface. The surface residence times observed for lunar rocks of the order of 10 m.y. (derived from the track densities of iron group nuclei) restrict the mass range of impacting particles of interest to masses less than about 1.01 gram. Extrapolation downward to smaller masses following flux distributions suggested by early satellite data and photographic meteor observations leads to absurd rates of abrasion. Consistent with the observed crater populations on the lunar rocks and with the Pegasus, Explorer, and Pioneer satellite data, the slope of the mass-flux distribution must decrease markedly for masses below 1 to .1 microgram.

Gault, D. E.↗
NASA NTRS1990

A rough-surface thermophysical model for airless planets

A model for determining diurnal temperatures in spherical-section depressions and which encompasses both subsurface heat-flow and direct and scattered sunlight effects is presently applied to the disk-integrated thermal emission of a rough planetary surface with nonzero thermal inertia. Attention is given to the variation with roughness and thermal inertia of the beaming parameter eta, which characterizes zero-phase thermal emission by comparison with a smooth, nonrotating body and is almost independent of albedo for a given surface roughness. The thermal phase curve of Ceres is noted to be well matched by the model features of (1) prograde rotation, (2) 44-deg rms surface slope, and (3) a thermal inertia that is 30 percent of the lunar value.

Spencer, John R.↗
NASA NTRS2013

Helicopter Flight Test of a Compact, Real-Time 3-D Flash Lidar for Imaging Hazardous Terrain During Planetary Landing

A second generation, compact, real-time, air-cooled 3-D imaging Flash Lidar sensor system, developed from a number of cutting-edge components from industry and NASA, is lab characterized and helicopter flight tested under the Autonomous Precision Landing and Hazard Detection and Avoidance Technology (ALHAT) project. The ALHAT project is seeking to develop a guidance, navigation, and control (GN&C) and sensing system based on lidar technology capable of enabling safe, precise crewed or robotic landings in challenging terrain on planetary bodies under any ambient lighting conditions. The Flash Lidar incorporates a 3-D imaging video camera based on Indium-Gallium-Arsenide Avalanche Photo Diode and novel micro-electronic technology for a 128 x 128 pixel array operating at a video rate of 20 Hz, a high pulse-energy 1.06 μm Neodymium-doped: Yttrium Aluminum Garnet (Nd:YAG) laser, a remote laser safety termination system, high performance transmitter and receiver optics with one and five degrees field-of-view (FOV), enhanced onboard thermal control, as well as a compact and self-contained suite of support electronics housed in a single box and built around a PC-104 architecture to enable autonomous operations. The Flash Lidar was developed and then characterized at two NASA-Langley Research Center (LaRC) outdoor laser test range facilities both statically and dynamically, integrated with other ALHAT GN&C subsystems from partner organizations, and installed onto a Bell UH-1H Iroquois "Huey" helicopter at LaRC. The integrated system was flight tested at the NASA-Kennedy Space Center (KSC) on simulated lunar approach to a custom hazard field consisting of rocks, craters, hazardous slopes, and safe-sites near the Shuttle Landing Facility runway starting at slant ranges of 750 m. In order to evaluate different methods of achieving hazard detection, the lidar, in conjunction with the ALHAT hazard detection and GN&C system, operates in both a narrow 1deg FOV raster-scanning mode in which successive, gimbaled images of the hazard field are mosaicked together as well as in a wider, 4.85deg FOV staring mode in which digital magnification, via a novel 3-D superresolution technique, is used to effectively achieve the same spatial precision attained with the more narrow FOV optics. The lidar generates calibrated and corrected 3-D range images of the hazard field in real-time and passes them to the ALHAT Hazard Detection System (HDS) which stitches the images together to generate on-the-fly Digital Elevation Maps (DEM's) and identifies hazards and safe-landing sites which the ALHAT GN&C system can then use to guide the host vehicle to a safe landing on the selected site. Results indicate that, for the KSC hazard field, the lidar operational range extends from 100m to 1.35 km for a 30 degree line-of-sight angle and a range precision as low as 8 cm which permits hazards as small as 25 cm to be identified. Based on the Flash Lidar images, the HDS correctly found and reported safe sites in near-real-time during several of the flights. A follow-on field test, planned for 2013, seeks to complete the closing of the GN&C loop for fully-autonomous operations on-board the Morpheus robotic, rocket-powered, free-flyer test bed in which the ALHAT system would scan the KSC hazard field (which was vetted during the present testing) and command the vehicle to landing on one of the selected safe sites.

Roback, VIncent E.↗
NASA NTRS2016

Low-Amplitude Topographic Features and Textures on the Moon: Initial Results from Detrended Lunar Orbiter Laser Altimeter (LOLA) Topography

Global lunar topographic data derived from ranging measurements by the Lunar Orbiter Laser Altimeter (LOLA) onboard LRO mission to the Moon have extremely high vertical precision. We use detrended topography as a means for utilization of this precision in geomorphological analysis. The detrended topography was calculated as a difference between actual topography and a trend surface defined as a median topography in a circular sliding window. We found that despite complicated distortions caused by the non-linear nature of the detrending procedure, visual inspection of these data facilitates identification of low-amplitude gently-sloping geomorphic features. We present specific examples of patterns of lava flows forming the lunar maria and revealing compound flow fields, a new class of lava flow complex on the Moon. We also highlight the identification of linear tectonic features that otherwise are obscured in the images and topographic data processed in a more traditional manner.

Moon↗
NASA NTRS1972

Near-terminator photography, part R

The advantages resulting from the use of near-terminator photography in lunar surface investigations are discussed. It is pointed out that, under near-terminator conditions, small changes in slope produce greater contrast changes than at high sun elevation angles. This desirable phenomenon is confirmed by an examination of the near-terminator photography taken during the Apollo 15 mission. Many of the photographs obtained show lunar surface areas within a few degrees of the terminator and are therefore of significant geologic interest. In addition, many geologic features stand out in a distinct manner not normal in conventional lunar photography, thus providing additional data on the surface morphology and the configuration of a large number of lunar surface structures.

Head, J. W.↗
NASA NTRSDate not supplied

ISRU Pilot Excavator Wheel Testing in Lunar Regolith Simulant

The ISRU Pilot Excavator, or IPEx, is a robotic excavator funded by NASA’s Space Technology Mission Directorate (STMD). The Concept of Operations for IPEx involves the robot driving on the lunar surface up to 70 km at a speed of up to 30 cm/s. As such, it is critical to the mission’s success to optimize the design of the wheels for performance in lunar conditions, specifically in lunar regolith. To achieve this, an array of tests was completed to observe the effects of various wheel design choices on the driving performance of the wheels in lunar regolith simulant. In order to facilitate testing, we designed a 12” dia. configurable wheel to allow for interchangeability between various wheel formations. Two types of wheel parts were designed to be swapped: cleats, which form the tread of the wheel; and grousers, which protrude from the treads. The test variables that we considered were as follows: square vs. round wheel shape, solid vs. perforated cleats, cleat spacing, grouser height, and grouser spacing. By combining different settings of each of these test variables, ten discrete wheel designs were created and tested. The configurable test wheels were mounted on the Regolith Advanced Surface Systems Operations Robot (RASSOR) developed at NASA’s Kennedy Space Center. In our experiments, the robot was driven at a controlled speed across a prepared surface of BP-1 lunar regolith simulant. Four types of tests were conducted: circle driving, straight driving, slope driving, and drawbar pull. The driving tests were chosen to mimic a variety of conditions in which IPEx may be expected to operate, and the drawbar pull test was chosen to provide a standard of comparison with existing wheel design literature. The circle and straight driving tests were each performed at different levels: for the circle driving test, the robot was driven at a constant linear speed and three different angular speeds, while for the straight driving test, the robot was driven at three different linear speeds. The data collected from these tests included the power usage from each of the wheels, measurements of the tread patterns left in the regolith surface, and the amount of slip the wheels experienced, which was calculated using data from an OptiTrack motion capture system. From the results of these experiments, we found that certain test variables were more significant than others in determining performance for each type of test, and no single wheel design clearly outperformed the others in all areas. The details of our findings will be discussed further in this paper. This data will be utilized to inform the design of the wheels for IPEx and can provide a basis for the design of wheels for future lunar terrain vehicles.

RASSOR↗
NASA NTRS1972

Spectrophotometry /0.3 to 1.1 micron/ of visited and proposed Apollo lunar landing sites.

The study uses information gained by analysis of the spectral properties of lunar samples in the laboratory, and telescope spectra of over 100 lunar areas, to provide information regarding the composition and mineralogy of each proposed lunar landing site. Attention is given to (1) the presence of pyroxenes which cause an absorption band near 0.95 micron in the lunar reflection spectrum, (2) the proportion of crystalline to glassy material present in the soil which is derived from the slope of the reflectivity curve between 0.4 and 0.7 micron and the strength of the 0.95 micron absorption band, and (3) the presence of Ti(3+) ions in the glasses on the lunar surface, which affects the reflection spectrum at blue and ultraviolet wavelengths.

Mccord, T. B.↗
NASA NTRS2011

Hazard Detection Software for Lunar Landing

The Autonomous Landing and Hazard Avoidance Technology (ALHAT) Project is developing a system for safe and precise manned lunar landing that involves novel sensors, but also specific algorithms. ALHAT has selected imaging LIDAR (light detection and ranging) as the sensing modality for onboard hazard detection because imaging LIDARs can rapidly generate direct measurements of the lunar surface elevation from high altitude. Then, starting with the LIDAR-based Hazard Detection and Avoidance (HDA) algorithm developed for Mars Landing, JPL has developed a mature set of HDA software for the manned lunar landing problem. Landing hazards exist everywhere on the Moon, and many of the more desirable landing sites are near the most hazardous terrain, so HDA is needed to autonomously and safely land payloads over much of the lunar surface. The HDA requirements used in the ALHAT project are to detect hazards that are 0.3 m tall or higher and slopes that are 5 or greater. Steep slopes, rocks, cliffs, and gullies are all hazards for landing and, by computing the local slope and roughness in an elevation map, all of these hazards can be detected. The algorithm in this innovation is used to measure slope and roughness hazards. In addition to detecting these hazards, the HDA capability also is able to find a safe landing site free of these hazards for a lunar lander with diameter .15 m over most of the lunar surface. This software includes an implementation of the HDA algorithm, software for generating simulated lunar terrain maps for testing, hazard detection performance analysis tools, and associated documentation. The HDA software has been deployed to Langley Research Center and integrated into the POST II Monte Carlo simulation environment. The high-fidelity Monte Carlo simulations determine the required ground spacing between LIDAR samples (ground sample distances) and the noise on the LIDAR range measurement. This simulation has also been used to determine the effect of viewing on hazard detection performance. The software has also been deployed to Johnson Space Center and integrated into the ALHAT real-time Hardware-in-the-Loop testbed.

Huertas, Andres↗
NASA NTRS1975

Lunar topography and the limb compression source regions

Data from the Apollo 15, 16, and 17 laser altimeters have been used to study slopes, elevations, and roughness in the identifiable regions on the moon which sporadically produce plasma compressions and magnetic-field enhancements in the solar wind/lunar void boundary when those regions are at a flow limb. It is found that occurrence rates for such 'limb compressions' derived from Explorer 35 satellite measurements are significantly correlated with peak, average, and RMS slopes in the source regions, whereas rates derived from Apollo 15 and 16 subsatellite data are not correlated with topography. This suggests that two or more mechanisms operate in the source regions to produce limb compressions. Together with the known correlation between limb compressions and local surface remanent magnetic fields, the results indicate that lunar magnetization is not strongly related to surface features.

Srnka, L. J.↗
NASA NTRS1981

Isotopic and REE studies of lunar basalt 12038 - Implications for petrogenesis of aluminous mare basalts

Sr, Nd, and Sm isotopic studies of lunar basalt 12038, one of the so-called aluminous mare basalts, are reported. The evolution of the Sr and Nd isotopic compositions and the rare earth element (REE) abundances is successfully modeled within the framework of the model developed by Nyquist et al. (1977, 1979) for Apollo 12 olivine-pigeonite and ilmenite basalts. It is pointed out that the isotopic and trace element features of 12038 can by modeled as produced by partial melting of a cumulate mantle source which crystallized from a lunar magma ocean with a chondrite-normalized REE pattern of constant negative slope. Chondrite-normalized La/Yb is equal to 2.2 for this hypothetical magma ocean pattern.

Nyquist, L. E.↗
NASA NTRS2010

Terrain Hazard Detection and Avoidance During the Descent and Landing Phase of the Altair Mission

This paper describes some of the environmental challenges associated with landing a crewed or robotic vehicle at any certified location on the lunar surface (i.e. not a mountain peak, permanently dark crater floor or overly steep terrain), with a specific focus on how hazard detection technology may be incorporated to mitigate these challenges. For this discussion, the vehicle of interest is the Altair Lunar Lander, being the vehicle element of the NASA Constellation Program aimed at returning humans to the moon. Lunar environmental challenges for such global lunar access primarily involve terrain and lighting. These would include sizable rocks and slopes, which are more concentrated in highland areas; small craters, which are essentially everywhere independent of terrain type; and for polar regions, low-angle sunlight, which leaves significant terrain in shadow. To address these issues, as well as to provide for precision landing, the Autonomous Landing and Hazard Avoidance Technology (ALHAT) Project was charted by NASA Headquarters, and has since been making significant progress. The ALHAT team considered several sensors for real-time hazard detection, settling on the use of a Flash Lidar mounted to a high-speed gimbal, with computationally intense image processing and elevation interpretation software. The Altair Project has been working with the ALHAT team to understand the capabilities and limitations of their concept, and has incorporated much of the ALHAT hazard detection system into the Altair baseline design. This integration, along with open issues relating to computational performance, the need for system redundancy, and potential pilot interaction, will be explored further in this paper.

Strhan, Alan L.↗
NASA NTRS1972

Geometric similitude of lunar and terrestrial craters.

Application of an elementary technique of dimensional analysis, that of testing for geometric similitude, suggests an impact genesis for most lunar craters. Geometrically similar phenomena fulfill four requirements: (1) log-log plots of paired descriptive variables are linear, (2) slopes of these plots equal ratios of the dimensions of the two variables, (3) intercepts of the plots are the same and (4) phenomena belong to the same general taxonomic group. Five topographic criteria are used to test lunar and terrestrial craters for geometric similitude: the variation of rim diameter with (1) interior depth, (2) exterior rim height, (3) exterior rim width and (4) rim crest circularity, and (5) variation of exterior rim height with crater depth. By all criteria, fresh bowl-shaped lunar craters between 10 m and 20 km in diameter are geometrically similar to fresh terrestrial meteorite craters and craters produced by chemical and nuclear explosives at shallow depths of burial. Most lunar craters exceeding 10-20 km in diameter fulfill only the last three criteria of similitude.

Pike, R. J.↗
NASA NTRS2009

Hazard Detection Methods for Lunar Landing

The methods and experiences from the Apollo Program are fundamental building blocks for the development of lunar landing strategies for the Constellation Program. Each of the six lunar landing Apollo missions landed under near ideal lighting conditions. The astronauts visually performed terrain relative navigation while looking out of windows, and were greatly aided by external communication and well lit scenes. As the LM approached the landing site, the astronauts performed visual hazard detection and avoidance, also under near-ideal lighting conditions. The astronauts were looking out of the windows trying to the best of their ability to avoid rocks, slopes, and craters and find a safe landing location. NASA has expressed a desire for global lunar access for both crewed and robotic sortie lunar exploration missions (Cook, 2007) (Dale, 2006). Early NASA architecture studies have identified the lunar poles as desirable locations for early lunar missions. These polar missions have less than ideal lighting conditions and will significantly affect the way a crewed vehicle plans to land at such locales. Consequently, a variety of hazard identification methods should be considered for use by the crew to ensure a high degree of safety. This paper discusses such identification methods applicable to the poorly lit polar lunar environment, better ensuring global access for the soon to be designed Lunar Lander Vehicle (LLV).

Brady, Tye↗
NASA NTRS1993

Lunar impact basins: New data for the nearside northern high latitudes and eastern limb from the second Galileo flyby

During the December 1992 Galileo Earth/Moon encounter the northern half of the nearside, the eastern limb, and parts of the western farside of the Moon were illuminated and in view, a geometry that was complementary to the first lunar encounter in December, 1990, which obtained images of the western limb and eastern farside. The Galileo Solid State Imaging System (SSI) obtained multispectral images for these regions during the second encounter and color ratio composite images were compiled using combinations of band ratios chosen on the basis of telescopic spectra and laboratory spectra of lunar samples. Ratios of images taken at 0.41 and 0.76 micron are sensitive to changes in the slope in the visible portion of the spectrum, and ratios of 0.99 and 0.76 micron relate to the strength of near-infrared absorptions due to iron-rich mafic minerals (0.76/0.99 ratio) such as olivine and pyroxene. Results of the analyses of the compositional diversity of the crust, maria, and Copernican craters are presented elsewhere. Primary objectives for lunar basin analysis for the second encounter include analysis of: the north polar region and the Humboldtianum basin; the characteristics of the Imbrium basin along its northern border and the symmetry of associated deposits; the origin of light plains north of Mare Frigoris and associated with several other basins; the nature and significance of pre-basin substrate; the utilization of the stereo capability to assess subtle basis structure; the identification of previously unrecognized ancient basins; basin deposits and structure for limb and farside basins; and assessment of evidence for proposed ancient basins. These data and results will be applied to addressing general problems of evaluation of the nature and origin of basin deposits, investigation of mode of ejecta emplacement and ejecta mixing, analysis of the origin of light plains deposits, analysis of basin deposit symmetry/asymmetry, investigation of basin depth of excavation and crustal stratigraphy, and assessment of models for basin formation and evolution. Here we discuss some preliminary results concerning lunar impact basins, their deposits, and prebasin substrates, using the same approaches that we employed for the Orientale and South Pole-Aitken basins using the data from the first encounter.

Head, J. W.↗