The probe was launched from Earth on August 17, 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's on-board KDU-414 engine.
It entered the atmosphere of Venus on December 15, 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 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 60km and atmospheric testing began with results showing the atmosphere to be 97% carbon dioxide. The parachute appeared to fail during the descent, resulting in a descent more rapid than planned. As a result the lander struck the surface of Venus at about 16.5 metres per second (54 ft/s) at 05:37:10 UTC. Landing coordinates are 5°S351°E / 5°S 351°E / -5; 351.
The probe appeared to go silent on impact but recording tapes kept rolling. A few weeks later, upon a review of the tapes, 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 not aimed correctly for strong signal transmission to Earth. The only data returned from the surface were temperature readings, which gave a temperature of 475 °C (887 °F).
Payloads are separated by bullets ( · ), launches by pipes ( | ). Manned flights are indicated in bold text. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in (brackets).