Venera 7
Template:Short description Template:Use dmy dates Template:Infobox spaceflight
Venera 7 (Template:Langx) was a 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 land on another planet and the first to transmit data from there back to Earth.<ref>Template:Cite magazine</ref>Template:Sfn
DesignEdit
The lander was designed to be able to survive pressure of up to Template:Convert and temperatures of Template:Convert.Template:Sfn 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.Template:Sfn This degree of hardening limited the amount of mass available for scientific instruments both on the probe itself and the interplanetary bus.Template:Sfn The interplanetary bus carried a solar-wind charged-particle detector and a cosmic-ray detector.<ref name=NSSDCA>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> On the lander were temperature and pressure sensors as well as an accelerometer to measure atmospheric density.Template:Sfn The probe also carried a radar altimeter.Template:Sfn
LaunchEdit
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.Template:Sfn During the flight to Venus, two in-course corrections were made using the bus's on-board KDU-414 engine.Template:Sfn
LandingEdit
Venera 7 entered the atmosphere of Venus on 15 December 1970.Template:Sfn The lander remained attached to the interplanetary bus during the initial stages of atmospheric entryTemplate:Sfn to allow the bus to cool the lander to Template:Cvt for as long as possible.Template:Sfn The lander was ejected once atmospheric buffeting broke the interplanetary bus's lock-on with Earth.Template:Sfn The parachute opened at a height of Template:Convert, and atmospheric testing began with results showing the atmosphere to be 97% carbon dioxide.Template:Sfn The parachute was initially reefed down to Template:Convert, opening to Template:Convert 13 minutes later, after the reefing line melted as designed.Template:Sfn Six minutes after the unreefing, the parachute started to fail, resulting in a descent more rapid than planned.Template:SfnTemplate:Sfn The parachute eventually failed completely, and the probe entered a period of freefall.Template:Sfn As a result, the lander struck the surface of Venus at about Template:Convert at 05:37:10 UTC.Template:Sfn The landing coordinates are Template:Venus coords and quad cat.<ref>Patrick Moore (2000). The Data Book of Astronomy. CRC Press. p. 92, Table 5-5, Missions to Venus, 1961–2000. Landing near Navka Planitia.</ref>
The probe appeared to go silent on impact,Template:Sfn but recording tapes kept rolling.<ref name=Klaes /> 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.<ref name=Klaes />Template:Sfn 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.<ref name=Klaes>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
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 Template:Convert.Template:Sfn<ref name=":0">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Using this temperature and models of the atmosphere, a pressure of Template:Cvt was calculated.Template:Sfn 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.Template:Sfn
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" />Template:Sfn
See alsoEdit
NotesEdit
ReferencesEdit
External linksEdit
- Venera 7 NASA NSSDC Master Catalog Data
- Plumbing the Atmosphere of Venus
Template:Venera Template:Venus spacecraft Template:Orbital launches in 1970