Exploration 

Due to Venus' thick cloud coverage, scientists were unable to see the geological features of its surface until recent times. The first spacecraft to visit Venus was the Mariner 2 in 1962. More than twenty other missions were subsequently launched and slowly, the surface of Venus was revealed. Besides Mariner 2, the three most successful missions to map Venus's surface was the NASA Pioneer Venus (1978), The Soviet Venera 15 and 16 missions (1983-1984) and the orbiting NASA Magellan radar mapping mission (1990-1994).