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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Lunar surface chemistry - A new imaging technique

Detailed chemical maps of the lunar surface have been constructed by applying a new weighted-filter imaging technique to Apollo 15 and Apollo 16 X-ray fluorescence data. The data quality improvement is amply demonstrated by (1) modes in the frequency distribution, representing highland and mare soil suites, which are not evident before data filtering, and (2) numerous examples of chemical variations which are correlated with small-scale (about 15 kilometer) lunar topographic features.

Andre, C. G.↗
NASA NTRS2020

LUNAR SURFACE GEOSCIENCE TRAINING FOR ASTRONAUTS

Geoscientists have been training and preparing astronauts to observe the Earth from space and explore other planetary surfaces with a legacy that reaches back to the early days of the space program. Continuing this legacy and critical function, a core NASA team has been closely coordinating with the Johnson Space Center (JSC) Flight Operations Directorate (FOD) as well as academic, research institutions, and other governmental partners to conduct a comprehensive geoscience training program that ranges from initial astronaut candidate training to preparing assigned crew for future lunar surface missions. Described below are the three program training phases (summarized in Figure 1), along with recent program highlights and forward planning. Given NASA’s increased planning and development efforts regarding near-term lunar surface science activities, we welcome ideas, concepts, capabilities, collaborations, and innovations to this astronaut training program.

T. G. Graff↗
NASA NTRS1993

Solar wind-induced secondary ions and their relation to lunar surface composition

Based on previous laboratory experiments simulating solar wind sputtering of lunar surface materials, it appears that solar wind ions sputter secondary ions in sufficient numbers to be measured from low-altitude lunar orbit. Solar wind protons are hundreds of times less efficient than those used in standard secondary ion mass spectrometry; nevertheless secondary ions of Na, Mg, Al, Si, K, Ca, Mn, Ti and Fe were observed sputtered from sample simulants of mare and highland soils. These secondary ion fluxes depend both on concentration in the soil and on probability of ionization; yields of easily ionized elements such as K and Na are relatively much greater than those for the more electronegative elements and compounds. The principal geochemical indicator elements Na, Mg, Al, Si, K, Ca, Ti, Mn and Fe are nevertheless detectable. However, it has not been shown that the observed secondary ions vary strictly one-to-one with their concentrations in the geochemically distinct soil simulants used here. While we have a first order understanding of secondary ion sputtering, it is not clear that the observed ion yields can be linked with great accuracy to the simulant's composition. The simulants were analyzed by electron microprobe to establish their detailed composition. The observed secondary ion fluxes can then be compared with the microprobe results. For example Ti(+) fluxes from the three simulants correspond to the true composition with accuracies of better than 10 percent for the high-Ti basalt, and about 20 percent for the low-Ti simulant. The highlands simulant produced a statistically insignificant Ti(+) count rate. Here we discuss the results of further SIMS experiments using the ASU/Center for Solid State Science facility. With careful isolation and preparation of samples, we avoid the problems of the previous experiments. In particular, we will make use of ground-up sample to mimic the sputtering behavior of regolith, and will avoid charging by placing the soil on a conducting indium substrate. We report the results of a blind test of the SIMS technique using a sample of unknown composition.

Elphic, R. C.↗
NASA NTRSDate not supplied

A Rapid Assessment of a Lunar Surface Laboratory Module

Johnson Space Center has piloted an innovation team known as the Forge to perform rapid turnaround, concurrent engineering studies. The Forge is intended to be able to pull together a team of strategically selected domain experts to innovatively solve a specified problem within a short period of time. The Forge’s inaugural project was the development of a Lunar Surface Laboratory Module concept. The lab module is intended as an option for the NASA Lunar Architecture Team and may allow for increased science productivity and return on investment than with only the Surface Habitat. The Forge team developed two concepts, a stationary laboratory and a mobile laboratory. Human factors evaluations have been conducted to determine the acceptability of the resulting design concepts. The human factors evaluations conducted include a card sort evaluation of the laboratories by science discipline and the System Usability Scale (SUS). The card sort focused subject matter expert expectations for the relative positioning of the laboratory functional areas, determining whether a given lab area should be adjacent to, or separated from, another. The SUS focused on layout efficiency. Both used human factors personnel and both life and physical scientists as subject matter experts. Each of these evaluations will focus primarily on objective data with limited subjective comments, reducing the time required for processing responses. The results of the card sort and SUS evaluations and their implications will be discussed. Based on the evaluation data, an overall acceptability of the Lunar Surface Laboratory Module produced by the Forge study can be determined. Lessons learned and recommendations for future use of human factors rapid assessment processes in early design trades will also be provided.

Forge↗
NASA NTRS1972

Directional behavior of thermal emission from a rough lunar surface.

The directionality is studied of the infrared emission from the lunar surface. A rough surface is postulated where the roughness is characterized by a crater field on a plain surface. The contour of the craters is assumed to be spherical. This makes it possible to determine the thermal emission on the basis of the temperature distribution obtained analytically by Adorjan (1970). By integrating the radiosities of both the craters and plain surfaces over a control area, and for given solar elevation and observation angles, the brightness temperatures are determined. The obtained results are presented in diagrams and discussed.

Adorjan, A. S.↗
NASA NTRS1982

Radar scattering laws for the lunar surface

Bistatic radar observations of quasi-specular scatter from the lunar surface at 13 and 116 cm wavelengths have been expressed in terms of probability densities of the underlying surface slope distributions. These show best agreement with a Hagfors scattering function, although other forms having predominantly Gaussian or exponential characteristics also occur. Estimates of root mean square (rms) surface slope derived from these function range from 4 deg rms in maria to at least 8 deg rms in highlands. These are values appropriate to 25 m horizontal scales and represent averages over tens of square kilometers of surface area. The effective scattering roughness varies with wavelength, most strongly in maria, where its behavior is consistent with that expected from an immature, i.e., unsaturated cratered surface. There is very little variation in scattering roughness with wavelength in highlands area.

Simpson, R. A.↗
NASA NTRS1992

High-resolution Elemental Mapping of the Lunar Surface

New instruments and missions are being proposed to study the lunar surface as a result of the resurgence of interest in returning to the Moon. One instrument recently proposed is similar in concept to the x-ray fluorescence detectors flown on Apollo, but utilizes fluorescence from the L- and M-shells rather than the K-shell. This soft X-Ray Flourescence Imager (XRFI) is discussed.

Edwards, Bradley C.↗