1971: The Soviet Union launches the Mars 2 probe. Consisting of an orbiter and a lander, its mission was to study the topography and atmosphere of Mars. On 27 November 1971, its descent module became the first human-made object to reach the surface of Mars, although an entry angle that was too steep caused it to crash without transmitting any ground data. The orbiter, however, transmitted precious data on the planet's magnetic field and temperature.

Image credits : USSR Post