Discoverer 20

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Discoverer 20
Mission type Optical reconnaissance
Operator US Air Force/NRO
Harvard designation 1961 Epsilon 1
Spacecraft properties
Spacecraft type KH-5 Argon
Bus Agena-B
Manufacturer Lockheed
Launch mass 1,110 kilograms (2,450 lb)
Start of mission
Launch date 17 February 1961, 20:25 (1961-02-17UTC20:25Z) UTC
Rocket Thor DM-21 Agena-B 298
Launch site Vandenberg SLC-1 launch pad 75-3-4
End of mission
Decay date 28 July 1962 (1962-07-29)
Orbital parameters
Reference system Geocentric
Regime Low Earth
Perigee 283 kilometers (176 mi)
Apogee 770 kilometers (480 mi)
Inclination 80.9 degrees
Period 95.2 minutes
The launch of Discoverer 20

Discoverer 20, also known as Corona 9014A, was an American area survey optical reconnaissance satellite which was launched in 1961. It was a KH-5 Argon satellite, based on an Agena-B.[1] Discoverer 20 was the first KH-5 to be launched, however it failed towards the end of its mission, when its film return capsule failed to separate from the main spacecraft.

The launch of Discoverer 20 occurred at 20:25 UTC on 17 February 1961. A Thor DM-21 Agena-B rocket was used, flying from Launch pad 75-3-4 at the Vandenberg Air Force Base.[2] Upon successfully reaching orbit, it was assigned the Harvard designation 1961 Epsilon 1.

Discoverer 20 was operated in a low Earth orbit, with a perigee of 283 kilometres (176 mi), an apogee of 770 kilometres (480 mi), 80.9 degrees of inclination, and a period of 95.2 minutes.[3] The satellite had a mass of 1,110 kilograms (2,450 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 were recorded onto 127-millimeter (5.0 in) film, and were to have been returned in an SRV before the satellite ceased operations. Due to a problem with the systems controlling the flight program, the spacecraft failed to eject its film capsule, and hence no images were returned.[4] Discoverer 20 decayed from orbit on 28 July 1962.[3]


  1. ^ Krebs, Gunter. "KH-5 Argon (Agena-B based)". Gunter's Space Page. Retrieved 22 June 2010. 
  2. ^ McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 22 June 2010. 
  3. ^ a b McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 22 June 2010. 
  4. ^ a b Wade, Mark. "KH-5". Encyclopedia Astronautica. Retrieved 22 June 2010. 
  5. ^ "Corona". Mission and Spacecraft Library. NASA. Retrieved 22 June 2010.