The Discoverer 7 spacecraft consisted of a main satellite body and a
separable reentry vehicle containing a recovery capsule. It was designed
to test launching techniques, propulsion, communications, orbital performance, engineering, and recovery techniques. The spacecraft was put into a near-polar orbit by the Thor-Agena A booster, but the power supply
inverter providing electricity to the control system did not operate
correctly, and Discoverer 7 began tumbling after launch. The reentry
vehicle failed to separate from the spacecraft.
The spacecraft was a cylindrical Agena A upper stage 1.5 m in diameter, 5.85 m long with a mass including propellants of roughly 3850 kg.
The mass excluding propellants was 794 kg, which included 140 kg for the
reentry vehicle. The capsule section (a.k.a. bucket) of the reentry
vehicle was 84 cm in diameter and 69 cm long and held a parachute, a black
and white film canister, and a tracking beacon. The capsule was designed
to be recovered by a specially equipped aircraft during parachute descent,
but was also designed to float to permit recovery from the ocean.
The Discoverer program was managed by the Advanced Research Projects Agency
of the Department of Defense and the U.S. Air Force. The primary goal of
the program was to develop a film-return photographic surveillance satellite
to assess how rapidly the Soviet Union was producing long-range bombers and ballistic missiles and where they were being deployed, and to take photos over the Sino-Soviet bloc to replace the the U2 spyplanes. It was part of the secret Corona program which was also used to produce maps and charts for the Department of Defense and other US government mapping programs. The goal of the program was not revealed to the public at the time, it was presented as a program to orbit large satellites to test satellite subsystems and investigate the communication and environmental aspects of placing humans in space, including carrying biological packages for return to Earth from orbit. In all, 38 Discoverer satellites were launched by February 1962, although the satellite reconnaissance program continued until 1972 as the Corona project. The program documents were declassified in 1995.