Discoverer 33

Discoverer 33, also known as Corona 9026, was an American optical reconnaissance satellite which was lost in a launch failure in 1961. It was the eighth of ten Corona KH-2 satellites, based on the Agena-B.^[1]

Discoverer 33

Mission type	Optical reconnaissance
Operator	US Air Force/NRO
Mission duration	Failed to orbit
Spacecraft properties
Spacecraft type	Corona KH-2
Bus	Agena-B
Manufacturer	Lockheed
Launch mass	1,150 kilograms (2,540 lb)
Start of mission
Launch date	23 October 1961, 19:23 (1961-10-23UTC19:23Z) UTC
Rocket	Thor DM-21 Agena-B 329
Launch site	Vandenberg LC-75-3-5
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Epoch	Planned
Discoverer ← Discoverer 32 Discoverer 34 → Corona KH-2 ← Corona 9021 Corona 9027 →

The launch of Discoverer 33 occurred at 19:23 UTC on 23 October 1961. A Thor DM-21 Agena-B rocket was used, flying from Launch Complex 75-3-5 at the Vandenberg Air Force Base.^[2] The launch was nominal through the Thor burn. Agena hydraulic system performance was erratic and resulted in numerous unplanned pitch and yaw maneuvers which drove the stage into an excessively lofted trajectory. At T+312 seconds hydraulic pressure was lost and the Agena began tumbling. The propulsion system shut down at T+322 seconds and the Agena fell into the Pacific. Following three occurrences of this failure mode in seven months, an extensive effort was made to redesign the Agena hydraulic system, improve weak points, and ensure that all systems were free of contamination.^[3]

Discoverer 33 was intended to have operated in a low Earth orbit. It had a mass of 1,150 kilograms (2,540 lb),^[4] and was equipped with a panoramic camera with a focal length of 61 centimetres (24 in), which had a maximum resolution of 7.6 metres (25 ft).^[5] It would have recorded images onto 70-millimeter (2.8 in) film, and returned this in a Satellite Recovery Vehicle at the end of its mission. The Satellite Recovery Vehicle carried by Discoverer 33 was SRV-553.