 Exploration of Vesta by fly-by and impacting penetrator was the second main target of the first plan of the multi-aimed Soviet Vesta mission, developed in cooperation with European countries for realisation in 1991–1994 but canceled due to the Soviet Union disbanding.In the early 1990s, NASA initiated the Discovery Program, which was intended to be a series of low-cost scientific missions.In 1996, the program's study team recommended a mission to explore the asteroid belt using a spacecraft with an ion engine as a high priority.