Sullivan's first space flight was launched from Kennedy Space Center, Florida, on 5 October, 1984 and consisted of an eight-day space mission, in which the team conducted scientific observations of the earth and a satellite refueling demonstration, using hydrazine fuel with the Orbital refueling system. Many useful experiments were conducted by Sullivan, and she almost completed 132 orbits of the Earth in less than 198 hours, becoming the second woman (and the first American female astronaut) to perform a space walk.
Her second flight on STS-31 occurred on 24 April, 1990. It was a five-day mission flight where the team completed 72 orbits of the Earth in about 121 hours. The mission deployed the Hubble Space Telescope, and conducted many tests, including protein crystal growth, polymer membrane processing, and the effects of magnetic fields on an iron arch.
The third flight on STS-45 (launched 24 March, 1992) was Sullivan's last. It was dedicated to NASA’s mission to study the Earth’s atmosphere. During her three flights, Sullivan has spent about 533 hours in space.