MISSION CONTROL CENTER STATUS REPORT # 3
STS-91
Wednesday, June 3, 1998  - 6 p.m. CDT
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  Discovery's astronauts spent much of today preparing for Thursday's
docking with the Mir space station and their face-to-face meeting with
astronaut Andy Thomas, who has been aboard the orbiting Russian
facility since late January.

  Discovery is scheduled to dock with the Mir at 11:58 a.m.. central
time tomorrow, marking the ninth meeting between the Shuttle and Mir,
and the first by Discovery.  The first seven docking missions were
conducted by Atlantis between June 1995 and September 1997 and the
eighth by Endeavour earlier this year.

  In preparation for tomorrow's rendezvous and docking, the astronauts
began assembling the checklists, cameras and other tools they will use
throughout the docking and installed the centerline camera in the
Orbiter Docking System.  The centerline camera will provide views of
docking targets and the docking module during the final phase of the
rendezvous activities.

  Shortly before 8:35 a.m. Thursday, from a position about eight miles
behind Mir, Commander Charlie Precourt and Pilot Dom Gorie will fire
Discovery's engines in a terminal initiation burn to put Discovery in
position to intercept the orbiting station.  The current schedule
shows Discovery arriving 600 feet below the Mir Space Station just
after 10 a.m.  central time.  Over the course of the next two hours,
Precourt and Gorie will slowly maneuver Discovery into position to
dock with Mir just before noon central time with hatch opening between
the two spacecraft taking place at 1:41 p.m.

  Late this afternoon, the crew was given permission to perform an
in-flight maintenance procedure designed to resolve at least part of
the Ku-band communication problem that is preventing video and high
data rate downlink capability.  The crew set up a bypass system which
allowed science data from the Alpha Magnetic Spectrometer (AMS) to be
downlinked via S-Band/FM communications when the Shuttle is within
range of a ground station.  Confirmation that the IFM procedure was
successful came shortly before 5:30 p.m. when high rate science data
was received at a ground station test facility located near the
Johnson Space Center.

  Flight controllers are continuing to evaluate data and consider
options for other work the crew may be asked to perform to try to
regain use of the Ku-Band/Comm mode operation.  Mission managers plan
to hold off giving approval for any additional Ku-Band troubleshooting
until after Discovery docks with the Mir station.

  Discovery's crew will begin an eight-hour sleep period at 8:06
p.m. this evening and receive a wake-up call from Mission Control at
4:06 a.m.  central time tomorrow to begin in earnest their rendezvous
activities.

  Discovery is currently in a 203 by 183 nm orbit, circling the Earth
once every 91 minutes.

  The next STS-91 status report will be issued at 6 a.m. central time
Thursday.