Vega 1 was an unmanned Soviet space probe launched in December 1984 from Moscow. Its mission was to study Venus' atmosphere and Halley's Comet, making it the last Soviet mission to Venus. It was a cooperative effort between the Soviet Union and multiple other countries. Vega 1 successfully landed a balloon on Venus and gathered data on its atmosphere before ending its mission in April 1985. It had a twin probe, Vega 2, and both gathered data during flybys of Halley's Comet in 1986.