OTD In Space - June 12: Venera 4 Launches On Mission To Venus

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.
But from the data collected by Venera 4, we learned that the Venus' surface temperatures were 500 degrees Celsius and the pressure was 75 times more than Earth's. It also found that Venus' atmosphere was composed of 90 to 95 percent carbon dioxide with no nitrogen.