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Venera 4 (Russian:Венера-4) was a probe in the Soviet Venera program for the exploration of Venus.
- Launch Date/Time: 1967 June 12 at 02:40:00 UTC
- On-orbit Dry Mass: 1106 kg
Venera 4 was launched from a Tyazheliy Sputnik (67-058B) towards the planet Venus with the announced mission of direct atmospheric studies. On October 18, 1967, the spacecraft entered the Venusian atmosphere and released two thermometers, a barometer, a radio altimeter, and atmospheric density gauge, 11 gas analyzers, and two radio transmitters operating in the DM waveband. The main bus, which had carried the capsule to Venus, carried a magnetometer, cosmic ray detectors, Lyman-alpha spectrometers for atomic hydrogen and oxygen, and charged particle (solar wind) traps. Signals were returned by the spacecraft, which braked and then deployed a parachute system after entering the Venusian atmosphere, until it reached an altitude of 24.96 km. Estimated landing place is somewhere near 19° N 38° E.
Venera-4 was the first successful probe to perform in-place analysis of the environment of another planet. It provided the first chemical analysis of the Venusian atmosphere, showing it to be primarily carbon dioxide with a few percent of nitrogen. It provided the first direct measurements proving that Venus was extremely hot, and the atmosphere was far more dense than expected.
