Editing Kosmos 27

{{Short description|Failed Soviet Venus impact probe}}
{{Use British English|date=March 2020}}
{{Use dmy dates|date=March 2020}}
{{Infobox spaceflight
| name                  = Kosmos 27
| image                 = 
| image_caption         =

| mission_type          = [[Venus]] impact probe
| operator              = [[OKB-1]]
| COSPAR_ID             = 1964-014A
| SATCAT                = 00770
| mission_duration      =

| spacecraft_type       = [[3MV|3MV-1]]
| manufacturer          = [[OKB-1]]
| dry_mass              = 948 kg<br/>(including an impact<br/>probe of 285 kg)<ref name=siddiqi/>
| launch_mass           = 6520 kg<ref>https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-014A - 27 February 2020</ref>
| power                 =

| launch_date           = 27 March 1964, 03:24:43 GMT
| launch_rocket         = [[Molniya (rocket)|Molniya 8K78]]<br/>s/n T15000-27
| launch_site           = [[Baikonur Cosmodrome|Baikonur]], [[Gagarin's Start|Site 1/5]]
| launch_contractor     = [[OKB-1]]
| decay_date            = 28 March 1964

| orbit_epoch           = 27 March 1964
| orbit_reference       = [[geocentric orbit|Geocentric]]<ref>https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1964-014A - 27 February 2020</ref>
| orbit_regime          = [[Low Earth orbit|Low Earth]]
| orbit_periapsis       = 167 km
| orbit_apoapsis        = 198 km
| orbit_inclination     = 64.8°
| orbit_period          = 88.7 minutes
| apsis                 = gee

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

'''Kosmos 27''' ({{langx|ru|Космос 27}} meaning ''Cosmos 27''), also known as '''Zond 3MV-1 No.3''' was a space mission intended as a [[Venus]] impact probe. The spacecraft was launched by a [[Molniya (rocket)|Molniya]] 8K78 carrier rocket from Baikonur. The Blok L stage and probe reached Earth orbit successfully, but the [[Spacecraft attitude control|attitude control]] system failed to operate.<ref>{{cite web|last1=Wade|first1=Mark |url=http://www.astronautix.com/craft/vena3mv1.htm|title=Venera 3MV-1|archive-url=https://web.archive.org/web/20020227125252/http://www.astronautix.com/craft/vena3mv1.htm|archive-date=2002-02-27 |website=Encyclopedia Astronautica|url-status=dead|access-date=17 February 2017}}</ref>

== Launch ==

Kosmos 27 was launched at 03:24:43 GMT on 27 March 1964, atop a [[Molniya (rocket)|Molniya]] 8K78 s/n T15000-27 carrier rocket flying from [[Gagarin's Start|Site 1/5]] at the [[Baikonur Cosmodrome]].

== Spacecraft ==

Kosmos 27 was a "third-generation" deep space planetary probes of the 3MV series of the Soviet Union. The 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.<ref name=siddiqi>{{cite book|url=https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf |archive-url=https://web.archive.org/web/20190424211923/https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf |archive-date=2019-04-24 |url-status=live |title=Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016|page=58|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>

== Mission ==

The probe was the first dedicated 3MV spacecraft that the Soviets launched (earlier missions had been of the test "Object-Probe" versions as Kosmos 21). It was designed to accomplish atmospheric entry into Venus followed by descent and impact. On 27 March 1964, it had a perigee of {{convert|167|km|mi}} and an apogee of {{convert|198|km|mi}}, with an inclination of 64.8° and an orbital period of 88.7 minutes.  The spacecraft successfully reached Earth orbit but failed to leave for Venus when the Blok L upper stage malfunctioned. The upper stage lost stable attitude due to a failure in the circuit of the power supply circuit that powered the valves for the attitude control system; hence, the stage remained uncontrollable and not ready to initiate a burn to leave Earth orbit. The problem was traced to a design error, the examination of [[telemetry]] data found that the failure was due to a design flaw in the circuitry of the BOZ unit, which resulted in power not being transferred to the attitude control jets on the Blok L stage, rather than one related to quality control. The spacecraft burned up in Earth's atmosphere the following day, on 28 March 1964. If successful, this mission would have been given a "Venera" designation.<ref name=siddiqi/>

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

== References ==
{{reflist}}

{{Venera}}
{{Orbital launches in 1964}}

{{DEFAULTSORT:Kosmos 0027}}
[[Category:Kosmos satellites]]
[[Category:Venera program]]
[[Category:Spacecraft launched in 1964]]
[[Category:Spacecraft which reentered in 1964]]
[[Category:3MV]]