On June 12, 1967, Venera 4 was launched into space on a mission to Venus, thus becoming the first spacecraft to transmit data from another planet’s atmosphere.
This was a Russian probe designed to study the atmosphere of Venus down to the surface.
At first, scientists believed that the probe had transmitted until contact with the surface of Venus.
But transmissions had ended at an altitude of 16 miles or 27 kilometers, when the extreme temperatures and high atmospheric pressure crushed the probe.
Source: https://www.space.com/39251-on-this-day-in-space.html
