Discoverer 20

Discoverer 20

Operator	US Air Force/NRO
Major contractors	Lockheed
Bus	KH-5 Argon Agena-B
Mission type	Optical reconnaissance
Launch date	17 February 1961 20:25 UTC
Carrier rocket	Thor DM-21 Agena-B 298
Launch site	Vandenberg LC-75-3-4
Orbital decay	28 July 1962
COSPAR ID	1961 Epsilon 1
Mass	1,110 kilograms (2,400 lb)
Orbital elements
Regime	Low Earth
Inclination	80.9°
Apoapsis	770 kilometres (480 mi)
Periapsis	283 kilometres (176 mi)
Orbital 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 around 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 Complex 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 (2,400 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-millimetre (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]

References

1. ^ Krebs, Gunter. "KH-5 Argon (Agena-B based)". Gunter's Space Page. http://space.skyrocket.de/doc_sdat/kh-5_ab.htm. Retrieved 22 June 2010. 
2. ^ McDowell, Jonathan. "Launch Log". Jonathan's Space Page. http://planet4589.org/space/log/launchlog.txt. Retrieved 22 June 2010. 
3. ^ ^{a b} McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. http://planet4589.org/space/log/satcat.txt. Retrieved 22 June 2010. 
4. ^ ^{a b} Wade, Mark. "KH-5". Encyclopedia Astronautica. http://www.astronautix.com/craft/kh5.htm. Retrieved 22 June 2010. 
5. ^ "Corona". Mission and Spacecraft Library. NASA. http://msl.jpl.nasa.gov/programs/corona.html. Retrieved 22 June 2010.