Venera 7 lander
On December 1970, the Soviet spacecraft Venera 7 became the first human object to land on another planet.
After the Mariner 2 was the first to fly by Venus, the Soviets became the first to put a lander on the surface, 8 years later.
The Descent of the Venera 7
The Venera 7 started it's descent to the surface. During the initial stages of the atmospheric entry, it remained to the interplanetary bus.
The main purpose of that was to keep the probe cool.
After the lander was ejected and it deployed it's parachute at about 60 kilometer altitude.
It immediately began its experiments, and one of the first readings revealed the atmosphere to be 97% carbon dioxide.
While descending, the parachutes appeared to malfucntion, causing the probe to impact harder than expected. The speed on impact was about 16.5 m/s or 37 mph.
First it was thought that the Venera 7 had stopped sending data, btu the recording tapes back on Earth kept rolling.
Surprising Discovery
A few weeks after the mission, the tapes were studies again and it was revealed that the Venera 7 had sent a very weak signal for about 23 minutes.
In that timeframe it was able to communicate that the surface temperature was 475 °C (887 °F) and the pressure was 90 atmospheres, which corresponds with about 900 m below sea level.
The Venera 7 was part of the Venera (Russian for Venus) series, a series of 16 probes sent to Venus between 1961 and 1984.