Martian topography and surface properties as seen by radar - The 1971 opposition.

Taking advantage of the favorable opposition of 1971, the Goldstone radar system, operating at 2388 MHz, was used to scan the Martian surface. Measurements of altitude and reflected power were taken approximately every 3 days. Each measurement represents an area 8 km E-W by 80 km N-S, the highest resolution attained to date. Altitude measurements obtained on different observing days were combined to produce altitude profiles for three complete rotations, each at different latitudes. Large-scale variations in altitudes cover a range of 14 km. Altitude changes of 5 in 30 km of longitude were observed. The altitude profiles show the heavy cratering of the surface, and several large craters (50-100 km) 1-2 km deep are easily seen.