Discoverer 20, also known as KH-5 9014A, was a

USAF The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...

photographic reconnaissance satellite under the supervision of the

National Reconnaissance Office The National Reconnaissance Office (NRO) is a member of the United States Intelligence Community and an agency of the United States Department of Defense which designs, builds, launches, and operates the reconnaissance satellites of the U.S. fe ...

(NRO) which was launched in 1961. Discoverer 20 was the first

KH-5 ARGON KH-5 ARGON was a series of reconnaissance satellites produced by the United States from February 1961 to August 1964. The KH-5 operated similarly to the CORONA series of satellites, as it ejected a canister of photographic film. At least 12 ...

satellite to be launched.

Launch

The launch of Discoverer 20 occurred at 20:24:00 GMT 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 Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in Key West, Florida * Vandenberg Sp ...

. Upon successfully reaching orbit, it was assigned the Harvard designation 1961 Epsilon 1. Discoverer 20 was operated in a

low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...

, with a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

of , an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ell ...

of , 80.91° of

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

, and a

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

of 95.81 minutes. The satellite was equipped with a frame

camera A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with a ...

with a focal length of , which had a maximum resolution of . Images were recorded onto film, and were to have been returned in a Satellite Recovery Vehicle (SRV) before the satellite ceased operations.

Mission

Discoverer 20 was placed in a near-polar orbit to continue evaluation of the Agena-B system, with particular emphasis on the spacecraft's stabilization system in order to overcome instability problems encountered on the previous DISCOVERER and to attempt ejection, deceleration, reentry through the atmosphere, and recovery of an instrument package. The satellite's scientific experiment package of radiation dosimeters, infrared radiometers, and microwave band detectors was identical to that of Discoverer 18 (launched 7 December 1960). Also included were the necessary telemetry and a reentry capsule. The capsule was a bowl-shaped configuration in diameter and in deep. A conical afterbody increased the total length to about . The recovery capsule payload included photographic film packs, nuclear track plates, and biological specimens. In addition to the external lights for optical tracking, the satellite carried a precision tracking experiment. The total package weighed 1,110 kg (2,450 lb). Recovery of the capsule was not attempted due to a system malfunction, and thus the scientific experiment data obtained were limited. Discoverer 20 decayed from orbit on 28 July 1962.

References

Spacecraft launched in 1961 Spacecraft which reentered in 1962 {{US-spacecraft-stub