Terrain analysis of the lunar equatorial belt

The U. S. Geological Survey began, in November 1963, a terrain analysis of the lunar equatorial belt (10°N-10°S, 60° W15°E), on behalf of the National Aeronautics and Space Administration. The purpose of the study is to establish a quantitative classification system in terms of different degrees of relative resolvable roughness, using the best available earth based techniques, the resolution of which averages one kilometer. Those parts of the lunar surface that have the least resolvable roughness at this scale have the highest statistical probability of containing safe landing areas at the one to ten meter scale for both manned and unmanned spacecraft.

This preliminary report is based on eight months work prior to July 1, 1964: an unreviewed manuscript was submitted initially to the National Aeronautics and Space Administration on July 27, 1964. The report does not include any data derived from Ranger VII, and manuscript review subsequent to Ranger VII has not revealed the need for any significant changes in the conclusions.

The major results are: 1) a quantitative terrain classification of the equatorial belt, chiefly in the form of a map (Plate 1), but including slope frequency distribution curves for each unit; 2) four larger scale maps (1:1, 000, 000) of the central part of the belt showing the areal distribution pattern of approximately 30, 000 individual slope measurements; 3) a large scale terrain map of the Flamsteed area, studied visually at the Lick 36" refractor, to determine the relative surface roughness below the limit of photographic resolution: 4) a full discussion of all the major techniques employed in the study, i.e. photometric slope measurement, slope measurement by shadow variation high resolution photography, and visual study techniques; 5) an extrapolation of derived roughness information below the of photographic resolution. The extrapolation is based primarily on the behavior of the lunar slope data through a wide range of resolution and on information derived from studies of different terrestrial areas at varying degrees of resolution.