Where No (American) Probe Had Gone Before

The Pioneer Venus spacecraft parachutes through Venus' thick and possibly stormy atmosphere in this artist's concept. The spacecraft, which also released three small probes, arrived at Venus on December 9, 1978. The fleet transmitted important readings on conditions through the planet's entire atmosphere. Pioneer Venus was the first and so far only American mission to descend through the atmosphere, although several Soviet probes managed to land on the surface. [NASA]