Engineering topics

Roush, Ted L.

Publications and source records attributed to Roush, Ted L..

58 records · Page 4

NASA NTRS1992

Estimates of absolute flux and radiance factor of localized regions on Mars in the 2-4 micron wavelength region

IRTF spectrophotometric observations of Mars obtained during the 1986 opposition are the bases for the present estimates of 2.0-4.15 micron absolute flux and radiance factor values. The bright/dark ratios obtained show a wavelength dependence similar to that observed by Bell and Crisp (1991) in 1990, but the spectral contrast for 1986 is lower than in those observations; this difference could be due to changes in the location, sample are size, and/or suspended atmospheric dust.

Roush, Ted L.↗

NASA NTRS1988

A search for water on the moon at the Reiner Gamma Formation - A possible site of cometary coma impact

Earth-based telescopic measurements of the Reiner Gamma Formation in the 3-micron region were made to search for evidence of water at this proposed site of cometary interaction with the lunar surface. Comparison of the spectra of Reiner Gamma and laboratory measurements of a variety of minerals with adsorbed water or structural OH(-) show that there is no evidence for water at the locations measured. While these measurements rule out the presence of abundant bound H2O at these locations, they do not exclude the presence of OH(-) bearing minerals that have absorptions not detectable through the wet terrestrial atmosphere. The possible effects of high lunar temperatures on the reflectance spectra were examined, and it was concluded that these effects would not obscure a bound water absorption if it were present. Upper limits on the amount of water that could be present at the locations observed and remain undetected are 2.25 average wt pct for a mixture consisting of discrete patches of water-bearing and water-free minerals and 0.01 wt pct for an intimate mixture of these two materials.

Roush, Ted L.↗

NASA NTRS1987

Reflectance spectra of mafic silicates and phyllosilicates from .6 to 4.6 microns

The results of spectral measurements for mafic silicates are given. The study provided valuable spectral reflectance information about mafic silicates and phyllosilicates in the 2.5 to 4.6 micron wavelength region. It was shown that the reflectance of these materials is strongly affected by the presence of H2O and OH. Therefore, the identification of these absorbing species is greatly enhanced.

Roush, Ted L.↗

NASA NTRS1987

Possible temperature variation effects on the interpretation of spatially resolved reflectance observations of asteroid surfaces

In virtue of the extent to which the visible and near-IR spectral reflectance of minerals that may be encountered on asteroid surfaces is a function of temperature, surface temperature distributions must be taken into account in the mineralogical evaluation of spectral reflectance data obtained from a spatially resolved asteroid surface. Possible errors of this type are presently illustrated for the case of a silicate mineral assemblage measured at the various temperatures that may be encountered over an asteroid surface, in order to allow optimal mineralogical data extraction.

Roush, Ted L.↗