Cosmos 21
Encyclopedia
Kosmos 21 was a Soviet spacecraft with an unknown mission. This mission has been tentatively identified by NASA as a technology test of the Venera
series space probes. It may have been an attempted Venus
flyby, presumably similar to the later Kosmos 27 mission, or it may have been intended from the beginning to remain in geocentric orbit
. In any case, the spacecraft never left Earth orbit after insertion by the SL-6/A-2-e launcher. The orbit decayed on November 14, three days after launch.
Beginning in 1962, the name Kosmos
was given to Soviet spacecraft which remained in Earth orbit, regardless of whether that was their intended final destination. The designation of this mission as an intended planetary probe is based on evidence from Soviet and non-Soviet sources and historical documents. Typically Soviet planetary missions were initially put into an Earth parking orbit
as a launch platform with a rocket engine and attached probe. The probes were then launched toward their targets with an engine burn with a duration of roughly 4 minutes. If the engine misfired or the burn was not completed, the probes would be left in Earth orbit and given a Kosmos designation.
Venera
The Venera series probes were developed by the Soviet Union between 1961 and 1984 to gather data from Venus, Venera being the Russian name for Venus...
series space probes. It may have been an attempted Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
flyby, presumably similar to the later Kosmos 27 mission, or it may have been intended from the beginning to remain in geocentric orbit
Geocentric orbit
A geocentric orbit involves any object orbiting the Earth, such as the Moon or artificial satellites. Currently there are approximately 2,465 artificial satellites orbiting the Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center...
. In any case, the spacecraft never left Earth orbit after insertion by the SL-6/A-2-e launcher. The orbit decayed on November 14, three days after launch.
Beginning in 1962, the name Kosmos
Cosmos (satellite)
Kosmos is a designation given to a large number of satellites operated by the Soviet Union and subsequently Russia. Kosmos 1, the first spacecraft to be given a Kosmos designation, was launched on March 16, 1962....
was given to Soviet spacecraft which remained in Earth orbit, regardless of whether that was their intended final destination. The designation of this mission as an intended planetary probe is based on evidence from Soviet and non-Soviet sources and historical documents. Typically Soviet planetary missions were initially put into an Earth parking orbit
Parking orbit
A parking orbit is a temporary orbit used during the launch of a satellite or other space probe. A launch vehicle boosts into the parking orbit, then coasts for a while, then fires again to enter the final desired trajectory...
as a launch platform with a rocket engine and attached probe. The probes were then launched toward their targets with an engine burn with a duration of roughly 4 minutes. If the engine misfired or the burn was not completed, the probes would be left in Earth orbit and given a Kosmos designation.