Venera 7 () 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. 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 to measure atmospheric density. The probe also carried a radar altimeter. 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 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 , and atmospheric testing began with results showing the atmosphere to be 97% carbon dioxide. The parachute was initially reefed down to , opening to 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 . 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