Main Events In US Shuttle History

COLUMBIA April 12-14, 1981: First of four test flights to demonstrate orbiter's ability.

Nov. 12-14, 1981: First time a spacecraft was reused for flight.

Nov. 11-16, 1982: Launch of two communication satellites.

Nov. 28-Dec. 8, 1983: First Spacelab carried in the payload bay.

CHALLENGER

April 4-9, 1983: First shuttle-based spacewalk.

June 18-24, 1983: First retrieval of an object from orbit and first US woman in space, Sally Ride.

Feb. 3-11, 1984: Use of backpack propulsion unit that allows astronauts to maneuver in space independent of the orbiter.

April 29-May 6, 1985: Second Spacelab mission and materials-processing experiments.

Jan. 28, 1986: Launch accident.

DISCOVERY

Aug. 30-Sept. 5, 1984: Launch of three communications satellites.

Nov. 8-16, 1984: Launch of two communications satellites and retrieval of two others sent into unusable orbits on flight 10 (Feb. 1984).

June 17-24, 1985: Deployment a low-cost Spartan scientific satellite and retrieval after a period of free flight.

April 25, 1990: Launch of the Hubble Space Telescope.

ATLANTIS

Oct. 3-10, 1985: Defense department mission.

Nov. 26-Dec. 3, 1985: Astronauts experimented with assembly of structures in orbit.

Jan. 12-18, 1986: Photos and spectral images of Comet Halley.