The Soviet Union launched the first space probe towards Venus on 4 February 1961. However, this failed, and so did their next several attempts. The Americans, too, came unstuck on their first attempt. It was not to be expected that such a sophisticated endeavour as the first flight to another planet would be achieved easily, and both teams soon tried again. In the end, it was the Americans who got a working spacecraft to Venus first.

The Venus Mariners: the first close-up views

The US space agency NASA was set up in 1958 and among its first tasks was the development of the Pioneer series of small spacecraft to explore the interplanetary medium near the Earth. These were followed by the Surveyor series, which targeted the Moon. A larger spacecraft than these would be needed to go on to even the closest planets, and NASA gave the job to its newly acquired centre in Southern California, the Jet Propulsion Laboratory (JPL). Before this, JPL had been an Army Air Corps facility for the development of rocket engines, with the name dating back to 1943. The new series of spacecraft was called Mariner, and Venus was its first target.