Discoverer 20
Encyclopedia
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
. 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
. 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 (175.8 mi), an apogee
of 770 kilometres (478.5 mi), 80.9 degrees of inclination
, and a period
of 95.2 minutes. The satellite had a mass of 1110 kilograms (2,447.1 lb), and was equipped with a frame camera with a focal length
of 76 millimetres (3 in), which had a maximum resolution of 140 metres (459.3 ft). Images were recorded onto 127 millimetres (5 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. Discoverer 20 decayed from orbit on 28 July 1962.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
area survey optical reconnaissance satellite which was launched in 1961. It was a KH-5 Argon satellite, based around an Agena-B
RM-81 Agena
The RM-81 Agena was an American rocket upper stage and satellite support bus which was developed by Lockheed initially for the canceled WS-117L reconnaissance satellite program...
. 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
Thor-Agena
Thor-Agena was a series of orbital launch vehicles. The rockets used Thor first stages and Agena second stages. They are thus cousins of the more famous Thor-Deltas, which founded the Delta rocket family. The first attempted launch of a Thor-Agena was in January 1959...
rocket was used, flying from Launch Complex 75-3-4 at the Vandenberg Air Force Base
Vandenberg Air Force Base
Vandenberg Air Force Base is a United States Air Force Base, located approximately northwest of Lompoc, California. It is under the jurisdiction of the 30th Space Wing, Air Force Space Command ....
. Upon successfully reaching orbit, it was assigned the Harvard designation 1961 Epsilon 1.
Discoverer 20 was operated in a low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
, with a perigee
Apsis
An apsis , plural apsides , is the point of greatest or least distance of a body from one of the foci of its elliptical orbit. In modern celestial mechanics this focus is also the center of attraction, which is usually the center of mass of the system...
of 283 kilometres (175.8 mi), an apogee
Apsis
An apsis , plural apsides , is the point of greatest or least distance of a body from one of the foci of its elliptical orbit. In modern celestial mechanics this focus is also the center of attraction, which is usually the center of mass of the system...
of 770 kilometres (478.5 mi), 80.9 degrees of inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
, and a period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
of 95.2 minutes. The satellite had a mass of 1110 kilograms (2,447.1 lb), and was equipped with a frame camera with a focal length
Focal length
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus...
of 76 millimetres (3 in), which had a maximum resolution of 140 metres (459.3 ft). Images were recorded onto 127 millimetres (5 in) film, and were to have been returned in an SRV
SRV
SRV may refer to:In computing:*SRV record as used in the Domain Name System*/srv, a directory on Unix-like computer systemsIn music:*Stevie Ray Vaughan, American blues musician...
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. Discoverer 20 decayed from orbit on 28 July 1962.