Pioneer Venus Radar Mapper Experiment

Science  23 Feb 1979:
Vol. 203, Issue 4382, pp. 806-808
DOI: 10.1126/science.203.4382.806


Altimetry and radar scattering data for Venus, obtained from 10 of the first 13 orbits of the Pioneer Venus orbiter, have disclosed what appears to be a rift valley having vertical relief of up to 7 kilometers, as well as a neighboring, gently rolling plain. Planetary oblateness appears unlikely to exceed 1/2500 and may be substantially smaller.