Date: 15 Dec 1970
Venera 7's objective was to transmit data from the surface of Venus. Since the Venera 4, 5 and 6 missions ended when intense atmospheric pressure crushed the probes far above the ground, Venera 7's landing capsule was designed to withstand pressures of up to 180 atmospheres and temperatures as high as 540 degree Celsius, more than enough to survive all the way to the planet's surface.
Venera 7 was the first spacecraft to transmit data from the surface of any extraterrestrial planet, though its success was uncertain at first. The probe sent data to Earth for 35 minutes while falling through the atmosphere, but the data transmission appeared to be replaced by noise as soon as the capsule hit the ground. Computer processing revealed, however, that this noise contained nearly 23 minutes of additional information at 1% of normal signal strength. The transmitted data indicated a surface temperature of 475 ± 20 degrees Celsius and a pressure of 90 ± 15 atmospheres.