Venera 7 (russian: Венера-7, lit=Venus 7) was a

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

spacecraft, part of the

Venera The Venera (, , which means "Venus" in Russian) program was the name given to a series of space probes developed by the Soviet Union between 1961 and 1984 to gather information about the planet Venus. Ten probes successfully landed on the s ...

series of probes to

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...

. 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 Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

Design

The lander was designed to be able to survive pressure of up to and temperatures of . This was significantly 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. The degree of hardening added mass to the probe which limited the amount of mass available for scientific instruments both on the probe itself and the interplanetary bus. The interplanetary bus carried a solar wind charged particle detector and a cosmic ray detector. On the lander there were temperature and pressure sensors as well as an

accelerometer An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...

to measure atmospheric density. The probe also carried a

radar altimeter A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it t ...

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 system, and a lander. During the flight to Venus, two in-course corrections were made using the bus' on-board

KDU-414 The KDU-414 (''Russian Корректирующая Двигательная Установка'', Corrective Propulsion Unit), is a pressure-fed liquid rocket Propulsion Unit developed and produced by the Isayev Design Bureau (today known as ...

engine.

Landing

Venera 7 entered the atmosphere of Venus on 15 December 1970. The lander remained attached to the interplanetary bus during the initial stages of atmospheric entry, to allow the bus to cool the lander to −8 °C (17 °F) for as long as possible. The lander was ejected once atmospheric buffeting broke the interplanetary bus's lock-on with Earth. The parachute opened at a height of 60 km, and atmospheric testing began with results showing the atmosphere to be 97% carbon dioxide. The parachute was initially reefed down to 1.8 square meters, opening to 2.5 square meters 13 minutes later, when the reefing line melted as designed. Six minutes after the unreefing, the parachute started to fail, resulting in a descent more rapid than planned. The parachute eventually failed completely, and the probe entered a period of freefall. As a result, the lander struck the surface of Venus at about at 05:37:10 UTC. The landing coordinates are .Patrick Moore, ''The data book of astronomy''. CRC Press, 2000, p. 92.
See Table 5-5, Missions to Venus, 1961–2000. Landing near Navka Planitia VenusLanderTopo

The probe appeared to go silent on impact, but recording tapes kept rolling. A few weeks later, upon a review of the tapes by the radio astronomer Oleg Rzhiga, another 23 minutes of very weak signals were found on them. 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. 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 ± 20 °C. Using the temperature, and models of the atmosphere, a pressure of 9.0 MPa (1,300 psi) ± 1.5

MPa MPA or mPa may refer to: Academia Academic degrees * Master of Performing Arts * Master of Professional Accountancy * Master of Public Administration * Master of Public Affairs Schools * Mesa Preparatory Academy * Morgan Park Academy * Mou ...

was calculated. From the spacecraft's rapid halt (from falling to stationary inside 0.2 seconds), it was possible to conclude that the craft had hit a solid surface with low levels of dust. The probe provided information about the surface of Venus, which could not be seen through a thick veil of atmosphere. 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.

Notes

References

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External links