Mariner 2 flew by Venus on December 14, 1962 -- the first spacecraft to reach another planet and send data back to Earth. Because clouds obscure the surface of Venus, there was no camera aboard. There were, however, several instruments that observed the planet as Mariner 2 passed by. They included a Microwave Radiometer, Infrared Radiometer, Magnetometer, Ionization Chamber, Particle Flux Detector, Cosmic Dust Detector, and Solar Plasma Analyzer. The Mariner-Venus 1962 Final Project report, which is available in the JPL Archives, contains detailed information about the experiment results (HC 8-92).