Radar Measurements of the Surface Topography and Roughness of Mars

Abstract

During the period surrounding the 1969 opposition, the planet Mars was observed with the Haystack radar to determine the topography in a belt near the equator. Elevation values obtained for the same surface location on Mars on different days of observation agree, for high signal‐to‐noise ratio cases, to within about 100 meters. Preliminary results show that the variation of surface height with longitude between latitudes 3°N and 12°N is similar to that measured for latitudes near 22°N during the 1967 opposition. The most notable difference is found near 215° longitude, where at 22°N there is a highland at Elysium, although at 5°N a lowland is found. Optically dark regions often have a high radar cross section. However, the topography shows no significant correlation with either the visual or the radar brightness.