Ranger 7 was the first US space probe to successfully transmit close images of the lunar surface back to Earth. It was also the first completely successful flight of the Ranger program.
Launched on July 28, 1964, Ranger 7 was designed to achieve a lunar-impact trajectory and to transmit high-resolution photographs of the lunar surface during the final minutes of flight up to impact.
The spacecraft carried six television vidicon cameras – two wide-angle (channel F, cameras A and B) and four narrow-angle (channel P) – to accomplish these objectives. The cameras were arranged in two separate chains, or channels, each self-contained with separate power supplies, timers, and transmitters so as to afford the greatest reliability and probability of obtaining high-quality video pictures. Ranger 7 transmitted over 4,300 photographs during the final 17 minutes of it flight.
After 68.6 hours of flight, the spacecraft landed between Mare Nubium and Oceanus Procellarum. This landing site was later named Mare Cognitum. The velocity at impact was 1.62 miles per second, and the performance of the spacecraft exceeded hopes. No other experiments were carried on the spacecraft.