Discoverer 24

Discoverer 24, also known as Corona 9018A, was an American area survey optical reconnaissance satellite which was launched in 1961 but failed to achieve orbit. It was a KH-5 Argon satellite, based on an Agena-B.^[1] It was the third KH-5 to be launched.

Discoverer 24

Mission type	Optical reconnaissance
Operator	US Air Force/NRO
Mission duration	Failed to orbit
Spacecraft properties
Spacecraft type	KH-5 Argon
Bus	Agena-B
Manufacturer	Lockheed
Launch mass	1,150 kilograms (2,540 lb)
Start of mission
Launch date	8 June 1961, 21:16 (1961-06-08UTC21:16Z) UTC
Rocket	Thor DM-21 Agena-B 302
Launch site	Vandenberg LC-1 launch pad 75-3-4
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Epoch	Planned

The launch of Discoverer 24

The launch of Discoverer 24 occurred at 21:16 UTC on 8 June 1961. A Thor DM-21 Agena-B rocket was used, flying from launch pad 75-3-4 at the Vandenberg Air Force Base.^[2] Thor performance was close to nominal; engine cutoff occurred at T+147 seconds, 3.3 seconds early. The first indication of trouble occurred when the Agena telemetry reported a massive electrical transient starting at T+77 seconds and lasting for about ten seconds. Another transient occurred at T+136 seconds. Unusually high temperatures were detected in the Agena equipment rack and near the payload fairing. The telemetry transmitter signal strength faded and had completely ceased by T+144 seconds. Staging was successfully achieved but with the loss of telemetry data it was unclear how the Agena's systems performed afterwards or if engine start was ever achieved. Radar tracking indicated Agena tumbling and a ballistic trajectory. It impacted the Pacific Ocean about 700 nautical miles downrange.^[3]

Discoverer 24 was 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 frame camera with a focal length of 76 millimetres (3.0 in), which had a maximum resolution of 140 metres (460 ft).^[5] Images would have been recorded onto 127-millimeter (5.0 in) film, and returned in a Satellite Recovery Vehicle, before the satellite ceased operations. The Satellite Recovery Vehicle carried aboard Discoverer 24 was SRV-541.^[4]