Mariner 2 Venus Flyby

Mariner 2, an American space probe to Venus, was the first robotic space probe to report successfully from a planetary encounter.^¹ The first successful spacecraft in the NASA Mariner program, it was a simplified version of the Block I spacecraft of the Ranger program and an exact copy of Mariner 1.^¹ The missions of the Mariner 1 and 2 spacecraft are sometimes known as the Mariner R missions.^¹ Original plans called for the probes to be launched on the Atlas-Centaur, but serious developmental problems with that vehicle forced a switch to the much smaller Agena B second stage.^¹ As such, the design of the Mariner R vehicles was greatly simplified.^¹ Far less instrumentation was carried than on the Soviet Venera probes of this period—for example, forgoing a TV camera—as the Atlas-Agena B had only half as much lift capacity as the Soviet 8K78 booster.^¹ The Mariner 2 spacecraft was launched from Cape Canaveral on August 27, 1962, and passed as close as 34,773 km (21,607 mi) to Venus on December 14, 1962.^¹