Editing Kosmos 21

{{Short description|Soviet spacecraft}}
{{Use British English|date=March 2020}}
{{Use dmy dates|date=March 2020}}
{{Infobox spaceflight
| name          = Kosmos 21
| image         = 
| image_caption =

| mission_type      = Deep space and return to Earth<br/>(test for Venus impact)<ref name=siddiqi/>
| operator          = [[OKB-1]]
| COSPAR_ID         = 1963-044A
| SATCAT            = 00687
| mission_duration  = 3 days

| spacecraft_type   = [[3MV|3MV-1A]]
| manufacturer      = [[OKB-1]]
| launch_mass       = 890 kg<ref name="nssdc.gsfc.nasa.gov">https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-044A - 27 February 2020</ref>

| launch_date       = 11 November 1963<br/>06:23:34 GMT
| launch_rocket     = [[Molniya (rocket)|Molniya]] 8K78M {{nowrap|[[serial number|s/n]] G103-18}}<ref name=siddiqi>{{cite book|url=https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf|title=Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016|pages=54–55|last1=Siddiqi|first1=Asif A.|lccn=2017059404|isbn=9781626830424|publisher=NASA History Program Office |edition=second|year=2018|id=SP2018-4041|series=The NASA history series|location=Washington, D.C.}}</ref>
| launch_site       = [[Baikonur Cosmodrome|Baikonur]], [[Gagarin's Start|Site 1/5]]
| launch_contractor = [[OKB-1]]

| disposal_type     = Upper stage failure
| decay_date        = 14 November 1963

| orbit_epoch       = 11 November 1963
| orbit_reference   = [[geocentric orbit|Geocentric]]<ref>https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1963-044A - 27 February 2020</ref>
| orbit_regime      = [[Low Earth orbit|Low Earth]]
| orbit_periapsis   = 182 km
| orbit_apoapsis    = 216 km
| orbit_inclination = 64.8°
| orbit_period      = 88.5 minutes
| apsis             = gee

| programme         = [[Venera program|Venera]]
| previous_mission  = [[Venera 2MV-2 No.1]]
| next_mission      = [[Venera 3MV-1 No.2]]
}}

'''Kosmos 21''' ({{langx|ru|Космос 21}} meaning ''Cosmos 21'') was a Soviet spacecraft. 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]] impact, 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 [[Geocentric orbit|Earth orbit]] after insertion by the [[Molniya (rocket)|Molniya]] launcher. The orbit decayed on 14 November 1963, three days after launch.

== Launch ==
Kosmos 21 was launched at 06:23:34 GMT on 11 November 1963, atop a [[Molniya (rocket)|Molniya]] 8K78 s/n G103-18 carrier rocket flying from [[Gagarin's Start|Site 1/5]] at the [[Baikonur Cosmodrome]].

== Spacecraft designation ==
Beginning in 1963, the name [[Kosmos (satellite)|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.<ref name="nssdc.gsfc.nasa.gov">https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-044A - 27 February 2020</ref>

The spacecraft's original development name before being given the Kosmos 21 denomination once it reached orbit was '''3MV-1 No.1'''.<ref name="LL">{{cite web|url=http://planet4589.org/space/log/launchlog.txt |title=Launch Log|last=McDowell|first=Jonathan|website=Jonathan's Space Page|access-date=10 January 2011}}</ref>

This was the first "third-generation" deep space planetary probes of the 3MV series of the Soviet Union. Like the second generation, Soviet engineers planned four types of the 3MV, the 3MV-1 (for Venus impact), 3MV-2 (for Venus flyby), 3MV-3 (for Mars impact), and 3MV-4 (for Mars flyby). The primary difference over the second-generation was vastly improved (and in many cases doubled) orientation system elements as well as improved onboard propulsion systems. While these four versions were meant to study Mars and Venus, the Soviets conceived of two additional variants of the series, similar but not
identical to the 3MV-1 and 3MV-4 versions, with the designations 3MV-1A and 3MV-4A.<ref name=siddiqi/>

These "Object-Probes" (ob'yekt-zond) were designed to verify key technological systems during simpler missions into deep space and back to Earth. A government decree on 21 March 1963 had approved two to three such "object-probe" missions, one of which (a 3MV-1A) was designed to depart from Earth's ecliptic (the orbital plane of Earth around the Sun) out to 12–16 million kilometers from Earth and then return to Earth after about six months when its orbit intersected with that of Earth again, aided by two mid-course corrections using its S5.45 main engine. The latter, capable of two firings, was a lighter version of that used on the 2MV model with higher specific impulse and longer burn time.<ref name=siddiqi/>

==Mission==
During this mission, the third and fourth stages separated abnormally, and after reaching Earth orbit, ground control lost telemetry (at 06:45:44 GMT) from the [[Blok D|Blok L]] [[Multistage rocket|upper stage]] designed to send the vehicle past the Moon. As a result, the spacecraft remained stranded in Earth orbit. The main engine turbopump of stage probably exploded upon ignition destroying the spacecraft. On 11 November 1963, it had a [[Apsis|perigee]] of {{convert|182|km|mi}} and an [[Apsis|apogee]] of {{convert|216|km|mi}}, with an [[Orbital inclination|inclination]] of 64.8°, and an [[orbital period]] of 88.5 minutes. The spacecraft was decay on 14 November 1963. With this mission, the Soviets began the practice of giving [[Kosmos (satellite)|Kosmos]] designations to obscure the failure of lunar and planetary probes that remained stranded in Earth orbit. If the spacecraft had successfully departed from Earth orbit, it would probably have been called [[Zond 1]].<ref name=siddiqi/>

==See also==
{{Portal|Spaceflight}}
* [[List of missions to Venus]]

==References==
{{reflist}}

{{Venera}}
{{Orbital launches in 1963}}

[[Category:Spacecraft launched in 1963]]
[[Category:1963 in the Soviet Union]]
[[Category:Kosmos satellites|Kosmos 0021]]
[[Category:Venera program|Kosmos 0021]]
[[Category:Spacecraft which reentered in 1963]]
[[Category:3MV]]