STS-80
Report # 27 
Saturday, Nov. 30, 1996, 6 p.m. CST  
 
 After a day of extensive ground analysis and testing of a balky
airlock hatch on Columbia, STS-80 mission managers decided to cancel
the two spacewalks that had been planned for astronauts Tammy Jernigan
and Tom Jones.

  Spacecraft communicator Dominic Gorie relayed the news to Jernigan
and Jones as the crew was awakened at 2:56 p.m. Central time for the
astronauts' 12th day in space.

  After detailed engineering analysis, shuttle managers could not
conclusively identify the problem that was causing the hatch handle to
jam and not allowing the hatch to open. Since the exact nature of the
problem could not be determined, managers decided it would not be
prudent to attempt the two planned spacewalks and risk unecessary
damage to the hatch or seals.

  Mission Operations Representative Randy Stone said one possible
suspect for the airlock hatch failure could be a mechanical problem in
the hatch handle's gearbox, a problem that cannot be fixed in
orbit. Stone said shuttle program officials are considering the
possibility of rescheduling the spacewalks on a future flight. The
spacewalks were designed to test tools and to refine techniques for
the assembly of the International Space Station, which is scheduled to
begin in about a year.

  Although the planned spacewalks have been canceled, engineers are
continuing an analysis of the problem to be as prepared as possible in
the highly unlikely event a contingency spacewalk is needed later in
the flight.  Also, flight planning will minimize the use of mechanical
systems aboard Columbia which could require repair on such a
contingency spacewalk. With all other shuttle systems in excellent
shape, Columbia is scheduled to remain in orbit for the full 16 days
planned for STS-80, and managers will meet Monday to decide on a
possible extension of the flight to allow additional astronomical
observations by the German ORFEUS-SPAS satellite.

  Because of the cancelled spacewalks, the crew is spending a quiet
day in orbit, conducting secondary experiments and exercising. They
will go to sleep at 7:56 a.m. Sunday.

  Columbia is in a 223 by 212 statute mile orbit, leading the
ORFEUS-SPAS satellite by 27 miles.
 
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