Discoverer 28, also known as Corona 9021, was an American optical

reconnaissance satellite A reconnaissance satellite or intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. The ...

which was lost in a launch failure in 1961. It was the seventh of ten Corona KH-2 satellites, based on the Agena-B. The launch of Discoverer 28 occurred at 00:01 UTC on 4 August 1961. A Thor DM-21 Agena-B rocket was used, flying from Launch Complex 75-1-1 at the Vandenberg Air Force Base. It failed to achieve orbit after the Agena's guidance and control system malfunctioned. Discoverer 28 was to have operated in a

low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...

. The satellite had a mass of , and was equipped with a panoramic camera with a

focal length The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...

of , which had a maximum resolution of . Images were to have been recorded onto film, and returned in a

Satellite Recovery Vehicle A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

. The Satellite Recovery Vehicle carried by Discoverer 28 was SRV-512.

References

Spacecraft launched in 1961 Satellite launch failures {{US-spacecraft-stub