View source for Venera 7

{{short description|Soviet lander mission to Venus (1970)}}
{{Use dmy dates|date=March 2020}}
{{Infobox spaceflight
| name              = Venera 7
| image             = Venera-7 spuskaemiy apparat.jpg
| image_caption     = Reproduction of the Venera 7 lander at the [[Sergei Pavlovich Korolyov Museum of Cosmonautics]]
| mission_type      = [[Venus]] lander
| operator          = [[Lavochkin]]
| COSPAR_ID         = 1970-060A 
| SATCAT            = 4489
| mission_duration  = Cruise: {{time interval|17 Aug 1970|15 Dec 1970|show=md}} <br />Lander: 23 minutes

| spacecraft        = [[3MV]] No. 630
| manufacturer      = [[Lavochkin]]
| dry_mass          = 
| launch_mass       = {{cvt|1180|kg|lb}}{{sfn|Siddiqi|2018|p=93}}
| landing_mass      = {{cvt|500|kg|lb}}
| power             =

| launch_date       = {{start-date|17 August 1970, 05:38:22|timezone=yes}}&nbsp;UTC{{sfn|Siddiqi|2018|p=93}}
| launch_rocket     = [[Molniya-M]]
| launch_site       = [[Baikonur Cosmodrome|Baikonur]] [[Baikonur Cosmodrome Site 31|31/6]]
| last_contact      = {{end-date|15 December 1970, 06:00|timezone=yes}}&nbsp;UTC

| orbit_epoch       = 
| orbit_reference   = [[Heliocentric orbit|Heliocentric]]
| orbit_periapsis   = {{convert|0.69|AU|e6km|abbr=unit}}
| orbit_apoapsis    = {{convert|1.01|AU|e6km|abbr=unit}}
| orbit_inclination = 2.0°
| orbit_period      = 287 days
| apsis             = helion
|interplanetary     = 
 {{Infobox spaceflight/IP
   |type            = lander
   |object          = [[Venus]]
   |arrival_date    = 15 December 1970, 05:37:10&nbsp;UTC
   |location        = {{Venus coords and quad cat|5|S|351|E}}
 }}

|instruments_list=
 {{Infobox spaceflight/Instruments
  |name1=COP-18-4M
  |name2=GS-4
  |name3=ITD
  |name4=DOW-1M
 }}

| insignia          = 1972 CPA 4166.jpg
| insignia_caption  = Seal of Venera 7
| insignia_size     = 180px

| programme         = '''[[Venera program]]'''
| previous_mission  = [[Venera 6]]
| next_mission      = [[Kosmos 359]]
}}

'''Venera 7''' ({{langx|ru|Венера-7|lit=Venus 7}}) was a [[Soviet Union|Soviet]] spacecraft, part of the [[Venera]] series of probes to [[Venus]]. When it landed on the Venusian surface on 15 December 1970, it became the first spacecraft to soft [[Landings on other planets|land on another planet]] and the first to transmit data from there back to [[Earth]].{{r|time-19710208}}{{sfn|Siddiqi|2018|pp=1, 3}}

== Design ==
The lander was designed to be able to survive pressure of up to {{convert|18|MPa|psi}} and temperatures of {{convert|580|°C}}.{{r|Huntress_2011}} This was much greater than what was expected to be encountered but significant uncertainties as to the surface temperatures and pressure of Venus resulted in the designers opting for a large margin of error.{{r|Huntress_2011}} This degree of hardening limited the amount of mass available for scientific instruments both on the probe itself and the [[Satellite bus|interplanetary bus]].{{r|Huntress_2011}} The interplanetary bus carried a solar-wind charged-particle detector and a cosmic-ray detector.{{r|NSSDCA}} On the lander were temperature and pressure sensors as well as an [[accelerometer]] to measure atmospheric density.{{r|Huntress_2011}} The probe also carried a [[radar altimeter]].{{r|Huntress_2011}}

== Launch ==
The probe was launched from Earth on 17 August 1970, at 05:38 [[UTC]]. It consisted of an interplanetary bus, based on the [[3MV (spacecraft)|3MV]] system, and a lander.{{sfn|Reeves|1994|pp=211–215}} During the flight to Venus, two in-course corrections were made using the bus's on-board [[KDU-414]] engine.{{sfn|Reeves|1994|pp=211–215}}

== Landing ==
[[File:VenusLanderTopo.jpg|thumb|left|Position of Venera landing sites. Red points denote sites returning images from the surface, black central dots sites of surface sample analysis. Map based on mapping from ''[[Pioneer Venus Orbiter]]'' and ''[[Magellan (spacecraft)|Magellan]]''.]]

Venera 7 entered the [[atmosphere of Venus]] on 15 December 1970.{{sfn|Reeves|1994|pp=211–215}} The lander remained attached to the interplanetary bus during the initial stages of atmospheric entry{{sfn|Reeves|1994|pp=211–215}} to allow the bus to cool the lander to {{cvt|−8|°C|°F}} for as long as possible.{{sfn|Reeves|1994|pp=211–215}} The lander was ejected once atmospheric buffeting broke the interplanetary bus's lock-on with Earth.{{sfn|Reeves|1994|pp=211–215}} The parachute opened at a height of {{convert|60|km}}, and atmospheric testing began with results showing the atmosphere to be 97% carbon dioxide.{{sfn|Reeves|1994|pp=211–215}} The parachute was initially [[reefed]] down to {{convert|1.8|m2}}, opening to {{convert|2.5|m2}} 13 minutes later, after the reefing line melted as designed.{{r|Huntress_2011}}Six minutes after the unreefing, the parachute started to fail, resulting in a descent more rapid than planned.{{r|Huntress_2011}}{{sfn|Reeves|1994|pp=211–215}} The parachute eventually failed completely, and the probe entered a period of freefall.{{r|Huntress_2011}} As a result, the lander struck the surface of Venus at about {{convert|16.5|m/s|km/h mph|abbr=on}} at 05:37:10 UTC.{{sfn|Reeves|1994|pp=211–215}} The landing coordinates are {{Venus coords and quad cat|5|S|351|E}}.{{r|Moore_2000}}

The probe appeared to go silent on impact,{{sfn|Reeves|1994|pp=211–215}} but recording tapes kept rolling.{{r|Klaes_1993}} A few weeks later, upon review of the tapes by radio astronomer Oleg Rzhiga, another 23 minutes of very weak signals were found on them.{{r|Klaes_1993|Harvey_2007}} The spacecraft had landed on Venus, and probably bounced onto its side, leaving the medium gain antenna aimed incorrectly for proper signal transmission to Earth.{{r|Klaes_1993}}

The probe transmitted information to Earth for 53 minutes, which included about 20 minutes from the surface.<ref name=":0"/> It was found that the temperature at the surface of Venus was {{convert|475|±|20|C}}.{{sfn|Reeves|1994|pp=211–215}}<ref name=":0">{{cite web|url=http://galspace.spb.ru/index89-2.html|title=Итоги работы станции "Венера-7"|language=ru|website=Galspace}}</ref> Using this temperature and models of the atmosphere, a pressure of {{cvt|9.0|±|1.5|MPa|psi}} was calculated.{{r|Ulivi_2007}} From the spacecraft's rapid halt (from falling to stationary inside 0.2 second), it was possible to conclude that the craft had hit a solid surface with low levels of dust.{{r|Ulivi_2007}}

The probe provided information about the surface of Venus that could not be seen through its thick atmospheric veil. The spacecraft confirmed that humans cannot survive on the surface of Venus. It excluded the possibility that there is any liquid water on the planet.<ref name=":0" />{{sfn|Reeves|1994|pp=211–215}}

== See also ==
{{Portal inline|Spaceflight}}
* [[List of missions to Venus]]
* [[Timeline of artificial satellites and space probes]]

== References ==
=== Citations ===
{{Reflist|refs=

<ref name="Harvey_2007">{{Cite book
| author1= B. Harvey
| title= Russian Planetary Exploration: History, Development, Legacy and Prospects
| url= https://books.google.com/books?id=8XC0WlTuujgC
| publisher= Springer
| year= 2007 
| pages= 114
| isbn= 978-0-387-46343-8 }}
</ref>

<ref name="Huntress_2011">{{cite book
| author1= W. T. Huntress
| author2= M. Y. Marov
| title= Soviet Robots in the Solar System: Mission Technologies and Discoveries
| url= https://books.google.com/books?id=rgl_C0XrKTUC
| publisher= [[Springer New York]] 
| year= 2011
| pages= 235–240
| isbn= 978-1-4419-7897-4 }}
</ref>

<ref name="Klaes_1993">{{Cite web
| author1= L. Klaes
| title= The Soviets and Venus, Part 1
| url= http://files.seds.org/pub/info/newsletters/ejasa/1993/jasa9302.txt
| date= 1993
| access-date= 29 September 2015
| archive-date= 29 September 2015
| archive-url= https://web.archive.org/web/20150929111636/http://files.seds.org/pub/info/newsletters/ejasa/1993/jasa9302.txt
| url-status= dead }}
</ref>

<ref name="Moore_2000">{{cite book
| author1= P. Moore
| title= The Data Book of Astronomy
| chapter= Table 5-5, Missions to Venus, 1961–2000. Landing near Navka Planitia
| chapter-url= https://books.google.com/books?id=2dSlDwAAQBAJ&lpg=PT116&pg=PT125
| publisher= CRC Press
| edition= 1st
| year= 2000
| pages= 92
| bibcode= 2000dba..book.....M
| isbn= 978-0-750-30620-1 }}
</ref>

<ref name="NSSDCA">{{cite web
| title= Venera 7
| url= https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-060A
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 6 October 2019
| archive-date= 11 April 2019
| archive-url= https://web.archive.org/web/20190411083507/https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-060A
| url-status= dead
}}</ref>

<ref name="time-19710208">{{cite magazine
| title= Science: Onward from Venus
| url= http://www.time.com/time/magazine/article/0,9171,909834,00.html
| magazine= [[Time (magazine)|Time]]
| date= 8 February 1971
| access-date= 2 January 2013
| archive-date= 21 December 2008
| archive-url= https://web.archive.org/web/20081221214000/http://www.time.com/time/magazine/article/0,9171,909834,00.html
| url-status= dead }}
</ref>

<ref name="Ulivi_2007">{{cite book
| author1= P. Ulivi
| author2= D. M. Harland
| title= Robotic Exploration of the Solar System Part I: The Golden Age 1957–1982
| url= 
https://books.google.com/books?id=Fi1mCYJWBwAC&pg=PA97
| publisher=Springer
| year= 2007
| pages= 97–99
| isbn= 978-0-387-49326-8 }}
</ref>

}}

=== Bibliography ===
* {{Cite book |last=Reeves |first=Robert |url=https://archive.org/details/superpowerspacer0000reev |title=The Superpower Space Race: An Explosive Rivalry Through the Solar System |publisher=[[Plenum Press]] |year=1994 |isbn=978-0-306-44768-6 |location=New York, NY |url-access=registration}}
* {{Cite book |last=Siddiqi |first=Asif A. |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 |publisher=NASA History Program Office |year=2018 |isbn=978-1-62683-042-4 |edition=Second |series=NASA SP |location=Washington, DC |lccn=2017059404 |id=SP2018-4041}}

== External links ==
* [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-060A Venera 7] {{Webarchive|url=https://web.archive.org/web/20190411083507/https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-060A |date=11 April 2019 }} NASA NSSDC Master Catalog Data
* [http://www.mentallandscape.com/V_Lavochkin1.htm Plumbing the Atmosphere of Venus]

{{Venera}}
{{Venus spacecraft}}
{{Orbital launches in 1970}}

{{DEFAULTSORT:Venera 7}}
[[Category:1970 in the Soviet Union]]
[[Category:Derelict landers (spacecraft)]]
[[Category:Spacecraft launched in 1970]]
[[Category:Venera program]]