Venera 4, also designated 4V-1 No.310, was a probe in the Soviet Venera program for the exploration of Venus. The probe comprised a lander, designed to enter the Venusian atmosphere and parachute to the surface, and a carrier/flyby spacecraft, which carried the lander to Venus and served as a communications relay for it. In 1967, it was the first successful probe to perform in-place analysis of the environment of another planet. Venera 4 provided the first chemical analysis of the Venusian atmosphere, showing it to be primarily carbon dioxide with a few percents of nitrogen and below one percent of oxygen and water vapor. While entering the atmosphere it became the first spacecraft to survive entry into another planet's atmosphere.

Wikipedia: https://en.wikipedia.org/wiki/Venera_4. Related NASA reference: https://nssdc.gsfc.nasa.gov/planetary/chronology.html#1967. Description adapted from Wikipedia contributors (CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0/).