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STS 51-I

        The orbiter Discovery flew the 20th Space Shuttle mission with its
launch at 6:58 a.m. EDT, Aug. 27, 1985.  Two earlier launch attempts,
one on Aug. 24 and another on Aug. 25 were scrubbed -- the first
because of poor weather and the second because the backup orbiter
computer failed and had to be replaced.  The successful Aug. 27
launch took place just before an approaching storm front reached the
launch pad area.

        The five-man STS 51-I crew included Joe H. Engle, commander; Richard
O. Covey, pilot; and three mission specialists James van Hoften, John
M. Lounge and William F. Fisher.  Their primary mission was to deploy
three commercial communications satellites and retrieve and repair
IV-3 which was deployed during the STS 51-D mission in April 1985 and
had malfunctioned.  In addition, a middeck materials processing
experiment was flown.

        The three communications satellites included l, a multi-purpose
spacecraft owned by Australia; the ASC-l owned and operated by the
American Satellite Co.; and IV-4 leased to the Department of Defense
by its builder, the Hughes Co.  Both l and ASC-l were deployed on
launch day, Aug. 27. IV-4, was deployed two days later.  All three
achieved proper geosynchronous orbits and became operational.

        On the fifth day of the mission, astronauts Fisher and van Hoften
began repair efforts on the malfunctioning IV-3 following a
successful rendezvous maneuver with Discovery.  The effort was slowed
because of a problem in the RMS elbow joint.  In any event, after a
second EVA by Fisher and van Hoften, the lever was repaired,
permitting commands from the ground to activate the spacecraft's
systems and eventually sending it into its proper geosynchronous
orbit.  The two EVAs took ll hours and 27 minutes.

        Discovery landed on Runway 23 at Edwards AFB at 6:16 a.m. PDT on
Sept. 3.  The flight took 7 days, 2 hours, 18 minutes, 42 seconds,
completing 111 orbits of the Earth.