The 1961 JPL Venus Radar Experiment

The feasibility of exploring the solar system by radar was demonstrated on March 10, 1961, when a radio signal was beamed at the planet Venus, and for the first time in history the return echo was detected within a few minutes. The JPL Venus radar experiment has resulted in 1) an improvement of the accuracy of the Astronomical Unit by more than two orders of magnitude, 2) a determination that the dielectric constant and apparent roughness of its surface material are not unlike surface materials commonly found on Earth, and 3) a determination of the rotation rate of Venus for its most probable axis of rotation. In addition, the experiment verified that reliable interplanetary UHF communication is possible over ranges of 50 to 75 million miles and that planetary radar observatories are both practical and useful. Many improvements in the state of the radar and communications art are noted.