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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Energetic electron scattering from the lunar remanent magnetic field

Description of a new technique for the detection of surface remanent magnetic fields from lunar orbiting spacecraft. Energetic (approximately 14-keV) electrons in the particle population surrounding the moon are observed by the Apollo 15 and 16 Subsatellite particle experiments to be scattered back up from the lunar surface by remanent magnetic fields. The regions of intense lunar remanent magnetization discovered by the Apollo 15 and 16 Subsatellite magnetometers are observed to strongly scatter the 14-keV electrons. In addition, several previously unreported regions of surface remanent magnetization on the lunar near-side are evident from the electron observation.

Howe, H. C.↗
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 NTRS1972

Guidance system operations plan for manned LM earth orbital and lunar missions using program luminary 1E. Section 2: Data links

Data links for the guidance system of manned lunar module orbital and lunar missions are presented. Subjects discussed are: (1) digital uplink to lunar module, (2) lunar module liftoff time increment, (3) lunar module contiguous block update, (4) lunar module scatter update, (5) lunar module digital downlink, and (6) absolute addresses for update program.

Hamilton, M. H.↗
NASA NTRS1975

A search for forward scattering of sunlight from lunar libration clouds

Data obtained with the white-light coronagraph on Skylab are analyzed to determine the radiance of forward scattered sunlight from particles in lunar libration regions. It is found that the libration regions could not be distinguished against the solar K + F coronal background, and upper limits are determined for the libration cloud radiance as well as density enhancements in the libration region. The actual spatial density enhancement is calculated on the basis of previous observations by Roach (1975). The radiance contrast of a possible model libration cloud is calculated with respect to the K- and F-corona/zodiacal-light background and is found to be a maximum in the vicinity of a solar elongation angle of the order of 30 deg.

Munro, R. H.↗
NASA NTRS1993

Interpretation of lunar and planetary electromagnetic scattering using the full wave solutions

Bistatic radar experiments carried out during the Apollo 14, 15, and 16 missions provide a very useful data set with which to compare theoretical models and experimental data. Vesecky, et al. report that their model for near grazing angles compares favorably with experimental data. However, for angles of incidence around 80 degrees, all the analytical models considered by Vesecky, et al. predict values for the quasi-specular cross sections that are about half the corresponding values taken from the Apollo 16 data. In this work, questions raised by this discrepancy between the reported analytical and experimental results are addressed. The unified full wave solutions are shown to be in good agreement with the bistatic radar taken during Apollo 14 and 16 missions. Using the full wave approach, the quasi-specular contributions to the scattered field from the large scale surface roughness as well as the diffuse Bragg-like scattering from the small scale surface roughness are accounted for in a unified self-consistent manner. Since the full wave computer codes for the scattering cross sections contain ground truth data only, it is shown how it can be reliably used to predict the rough surface parameters of planets based on the measured data.

Bahar, E.↗