Venera 7

The lander was designed to be able to survive pressure of up to {{convert|18|MPa|psi}} and temperatures of {{convert|580|°C}}.{{sfn|Huntress|Marov|2011|p=235}} 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.{{sfn|Huntress|Marov|2011|p=235}} This degree of hardening limited the amount of mass available for scientific instruments both on the probe itself and the interplanetary bus.{{sfn|Huntress|Marov|2011|p=235}} The interplanetary bus carried a solar-wind charged-particle detector and a cosmic-ray detector.{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-060A |title=Venera 7 |website=NASA Space Science Data Coordinated Archive |publisher=NASA |access-date=6 October 2019}} On the lander were temperature and pressure sensors as well as an accelerometer to measure atmospheric density.{{sfn|Huntress|Marov|2011|pp=236–240}} The probe also carried a radar altimeter.{{sfn|Huntress|Marov|2011|pp=236–240}}

The probe was launched from Earth on 17 August 1970, at 05:38 UTC. It consisted of an interplanetary bus, based on the 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}}

File:VenusLanderTopo.jpg and 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.{{sfn|Huntress|Marov|2011|pp=236–240}} Six minutes after the unreefing, the parachute started to fail, resulting in a descent more rapid than planned.{{sfn|Huntress|Marov|2011|pp=236–240}}{{sfn|Reeves|1994|pp=211–215}} The parachute eventually failed completely, and the probe entered a period of freefall.{{sfn|Huntress|Marov|2011|pp=236–240}} 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}}.Patrick Moore (2000). The Data Book of Astronomy. CRC Press. p. 92, Table 5-5, Missions to Venus, 1961–2000. Landing near Navka Planitia.

The probe appeared to go silent on impact,{{sfn|Reeves|1994|pp=211–215}} but recording tapes kept rolling. 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.{{sfn|Harvey|2007|p=114}} 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.{{Cite web |url=http://files.seds.org/pub/info/newsletters/ejasa/1993/jasa9302.txt |title=Larry Klaes, The Soviets and Venus, Part 1, 1993. |access-date=29 September 2015 |archive-url=https://web.archive.org/web/20150929111636/http://files.seds.org/pub/info/newsletters/ejasa/1993/jasa9302.txt |archive-date=29 September 2015 |url-status=dead }}

The probe transmitted information to Earth for 53 minutes, which included about 20 minutes from the surface. It was found that the temperature at the surface of Venus was {{convert|475|±|20|C}}.{{sfn|Reeves|1994|pp=211–215}}{{cite web|url=http://galspace.spb.ru/index89-2.html|title=Итоги работы станции "Венера-7"|language=ru|website=Galspace}} Using this temperature and models of the atmosphere, a pressure of {{cvt|9.0|±|1.5|MPa|psi}} was calculated.{{sfn|Ulivi|Harland|2007|pp=97–99}} 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.{{sfn|Ulivi|Harland|2007|pp=97–99}}

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.{{sfn|Reeves|1994|pp=211–215}}

• {{Portal inline|Spaceflight}}
• List of missions to Venus
• Timeline of artificial satellites and space probes

{{Reflist|30em}}

• {{Cite book |last=Harvey |first=Brian |url=https://books.google.com/books?id=8XC0WlTuujgC |title=Russian Planetary Exploration: History, Development, Legacy and Prospects |date=2007 |publisher=Springer |isbn=978-0-387-46343-8 |series=Springer-Praxis books in space exploration |location=Berlin}}
• {{Cite book |last=Huntress |first=Wesley T. |url=https://books.google.com/books?id=rgl_C0XrKTUC |title=Soviet Robots in the Solar System: Mission Technologies and Discoveries |last2=Marov |first2=Mikhail Ya |date=2011 |publisher=Springer New York |isbn=978-1-4419-7897-4 |series=Springer Praxis Bks |location=New York, NY}}
• {{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}}
• {{Cite book |last=Ulivi |first=Paolo |url=https://books.google.com/books?id=Fi1mCYJWBwAC |title=Robotic Exploration of the Solar System Part I: The Golden Age 1957–1982 |last2=Harland |first2=David M. |date=2007 |publisher=Springer |isbn=978-0-387-49326-8 |location=Chichester}}

• [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-060A Venera 7] 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 07}}

Category:1970 in the Soviet Union

Category:Derelict landers (spacecraft)

Category:Spacecraft launched in 1970

Category:Venera program