by D. Vogt

Created on: June 10, 2010

Venus is the most visited of the other planets in our solar system. This may be surprising to many: since the fall of the Soviet Union, the space program of which specialized in Venus exploration, and the rise of interest in the possible history of primitive life on Mars, the red planet has become the dominant target of planetary probe missions. Nevertheless, a large number of space probes have been sent to Venus, beginning with the Soviet Venera 1 (1961) and American Mariner 2 (1962), and extending to the European Venus Express, which arrived in 2006 and is still engaged in studying the planet.

- Soviet Venus Program -

Even today, the most accomplished series of space probes sent to Venus were those launched by the former Soviet Union, beginning with Venera 1 in 1961, which was the first interplanetary spacecraft and did manage to enter Venusian orbit, though it malfunctioned and failed soon after doing so. The Zond 1 probe, launched in 1964, suffered a similar fate; by the time it reached Venus in July of that year, Soviet scientists had already lost all contact and given up the probe for dead.

Despite the inauspicious beginnings, the Venera program continued, becoming arguably the most successful series of planetary landing missions until the Mars rover missions launched by NASA over the last decade or so. Venera 2 and Venera 3 were launched in 1966 to crash-land on Venus, the standard approach to lunar and planetary exploration at a time when landing technology was still technically unfeasible; Venera 2 failed, but Venera 3 managed to land, but not to communicate. The next entry vehicle, Venera 4, was promptly sent on a similar mission, and finally transmitted atmospheric data on its way down.

More Venera missions followed, leading to the first successful landing by Venera 7 in 1970. Several more Venera landers followed, with impressive achievements interspersed with occasional dramatic failures. However, the harsh environment on the surface of Venus meant that such missions were necessarily short-lived and limited. Venera 13, which sent back colour photographs of Venus for the first time in the 1980s, was designed for a simple half-hour mission in the several-hundred-degree heat; when instead it lasted for slightly over two hours, this was considered an impressive achievement. (By contrast, NASA probes on Mars have been able to survive and operate for many years.)

Its last pair of probes to Venus departed from the Venera model, and were instead designated

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