Discoverer 18
Encyclopedia
Discoverer 18, also known as Corona 9013, was an American
optical reconnaissance satellite which was launched in 1960. It was a KH-2 Corona
satellite, based around an Agena-B
.
The launch of Discoverer 18 occurred at 20:20:58 UTC on 7 December 1960. 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 1960 Sigma 1.
Discoverer 18 was operated in a low Earth orbit
, with a perigee
of 272 kilometres (169 mi), an apogee
of 535 kilometres (332.4 mi), 81.4 degrees of inclination
, and a period
of 92.6 minutes. The satellite had a mass of 1240 kilograms (2,733.7 lb), 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 (24.9 ft). Images were recorded onto 70 millimetres (2.8 in) film, and returned in a Satellite Recovery Vehicle, which was recovered three days after the launch. The Satellite Recovery Vehicle used by Discoverer 18 was SRV-508. Following the return of its images, Discoverer 18 remained in orbit until it decayed
on 2 April 1961. It was the first KH-2 satellite to complete its mission successfully.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
optical reconnaissance satellite which was launched in 1960. It was a KH-2 Corona
Corona (satellite)
The Corona program was a series of American strategic reconnaissance satellites produced and operated by the Central Intelligence Agency Directorate of Science & Technology with substantial assistance from the U.S. Air Force...
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...
.
The launch of Discoverer 18 occurred at 20:20:58 UTC on 7 December 1960. 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 1960 Sigma 1.
Discoverer 18 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 272 kilometres (169 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 535 kilometres (332.4 mi), 81.4 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 92.6 minutes. The satellite had a mass of 1240 kilograms (2,733.7 lb), and was equipped with a panoramic 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 61 centimetres (24 in), which had a maximum resolution of 7.6 metres (24.9 ft). Images were recorded onto 70 millimetres (2.8 in) film, and returned in a Satellite Recovery Vehicle, which was recovered three days after the launch. The Satellite Recovery Vehicle used by Discoverer 18 was SRV-508. Following the return of its images, Discoverer 18 remained in orbit until it decayed
Orbital decay
Orbital decay is the process of prolonged reduction in the altitude of a satellite's orbit.This can be due to drag produced by an atmosphere due to frequent collisions between the satellite and surrounding air molecules. The drag experienced by the object is larger in the case of increased solar...
on 2 April 1961. It was the first KH-2 satellite to complete its mission successfully.