- Discoverer 21
-
Discoverer 21 Operator US Air Force/ARPA Major contractors Lockheed Bus Agena-B Mission type Technology Launch date 18 February 1961
22:58 UTCCarrier rocket Thor DM-21 Agena-B 261 Launch site Vandenberg LC-75-3-5 Orbital decay 20 April 1962 COSPAR ID 1961 Zeta 1 Mass 1,110 kilograms (2,400 lb) Orbital elements Regime Low Earth Inclination 80.7° Apoapsis 1,026 kilometres (638 mi) Periapsis 243 kilometres (151 mi) Orbital period 97.4 minutes 
The launch of Discoverer 21
Discoverer 21, also known as RM-2, was an American satellite which was launched in 1961. It was a technology demonstration spacecraft, based around an Agena-B.[1]
The launch of Discoverer 21 occurred at 22:58 UTC on 18 February 1961. A Thor DM-21 Agena-B rocket was used, flying from Launch Complex 75-3-5 at the Vandenberg Air Force Base.[2] Upon successfully reaching orbit, it was assigned the Harvard designation 1961 Zeta 1.
Discoverer 21 was operated in a low Earth orbit, with a perigee of 243 kilometres (151 mi), an apogee of 1,026 kilometres (638 mi), 80.7 degrees of inclination, and a period of 97.4 minutes.[3] The satellite had a mass of 1,110 kilograms (2,400 lb),[4] and was used to demonstrate an engine restart,[5] and to test infrared sensors for the Midas programme.[4] It remained in orbit until 20 April 1962,[3] when it decayed and reentered the atmosphere.
References
- ^ Krebs, Gunter. "RM 1, 2 (Discoverer 19, 21)". Gunter's Space Page. http://space.skyrocket.de/doc_sdat/rm-1.htm. Retrieved 30 June 2010.
- ^ McDowell, Jonathan. "Launch Log". Jonathan's Space Page. http://planet4589.org/space/log/launchlog.txt. Retrieved 30 June 2010.
- ^ a b McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. http://planet4589.org/space/log/satcat.txt. Retrieved 30 June 2010.
- ^ a b Wade, Mark. "Midas". Encyclopedia Astronautica. http://www.astronautix.com/craft/midas.htm. Retrieved 30 June 2010.
- ^ "Discoverer 21". NSSDC Master Catalog. NASA. http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1961-006A. Retrieved 30 June 2010.
Discoverer satellites See also: Corona (satellite) · KH-5 Argon← 1960 · Orbital launches in 1961 · 1962 → Samos 2 | Tyazhely Sputnik | Venera 1 | Explorer 9 | Discoverer 20 | Discoverer 21 | Transit 3B · LOFTI-1 | S-45 | Korabl-Sputnik 4 | Korabl-Sputnik 5 | Explorer 10 | Discoverer 22 | Discoverer 23 | Vostok 1 | Mercury-Atlas 3 | Explorer 11 | S-45A | Discoverer 24 | Discoverer 25 | Transit 4A · Solrad 3 · Injun 1 | S-55 | Discoverer 26 | TIROS-3 | Midas 3 | Discoverer 27 | Discoverer 28 | Vostok 2 | Explorer 12 | Ranger 1 | Explorer 13 | Discoverer 29 | Samos 3 | Discoverer 30 | Mercury-Atlas 4 | Discoverer 31 | Discoverer 32 | Midas 4 · Westford 1 | Discoverer 33 | DS-1 No.1 | Mercury-Scout 1 | Discoverer 34 | Discoverer 35 | Transit 4B · TRAAC | Ranger 2 | Samos 4 | Mercury-Atlas 5 | Zenit-2 No.1 | Discoverer 36 · Oscar 1 | DS-1 No.2 | FTV-2203Payloads are separated by bullets ( · ), launches by pipes ( | ). Manned flights are indicated in bold text. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in brackets.Categories:- 1961 in spaceflight
- Artificial satellites formerly orbiting Earth
- United States spacecraft stubs
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