STS-76 Mission Summary
Launch
March 22, 1996,
3:13:04 a.m. EST
Launch set for March 21 pending resolution of issue concerning wiper O-rings
on nozzle-to-case joints on both Redesigned Solid Rocket Motors (RSRMs)
flown on previous mission, STS-75. Different situation from STS-71/STS-70
O-ring issue that occurred in 1995 and affected nozzle internal joint.
STS-75 gas paths went through polysulfide adhesive to, but not past, wiper
O-ring on nozzle-to-case joints. Similar gas paths observed on previous
missions, but STS-75 marked first time two different gas paths observed
in one nozzle-to-case joint, and on both RSRMs. After review, managers
concluded nozzle-to-case joint design was robust and safe to fly, and
launch preparations proceeded. First launch attempt set for March 21 scrubbed
prior to commencement of tanking operations March 20, due to concerns
about high winds. Launch reset for March 22 proceeded smoothly to on-time
liftoff. During ascent, leak occurred in hydraulic system powered by Auxiliary
Power Unit (APU) number 3. Leak stopped after hydraulic system shutdown
on-orbit. Mission managers concluded system would remain stable and proceeded
with plans for full-duration mission.
Landing
March 31, 1996,
5:28:57 a.m. PST
Runway 22, Edwards Air Force Base, Calif. Rollout distance: 8,357 feet
(2,547 meters). Rollout time: 55 seconds. Mission duration: nine days,
five hours, 15 minutes, 53 seconds. Landed revolution 145. Mission managers
re-scheduled landing from March 31 to March 30 in anticipation of rain
and clouds at KSC landing site, but landing attempts at KSC March 30 and
31 waved off due to weather before orbiter finally diverted to California.
More conservative weather criteria employed for landing due to leak in
APU number 3 hydraulic system and special measures taken during re-entry
to minimize use of this particular APU. Following waveoff March 30, payload
bay door reopening process interrupted when release indicators for payload
bay door centerline latches 9 through 12 on both sides failed to indicate
release, suggesting latches had not operated properly. Astronauts ventured
into SPACEHAB module in aft payload bay to visually inspect the latches,
which appeared to have opened as intended. Crew used manual mode to complete
opening of doors without further incident, and glitch attributed to microswitches.
Also, during prelanding preparations, three of 38 Reaction Control System
(RCS) thrusters failed, but backup thrusters were available to perform
same functions. Not considered a night landing because it occurred 11
minutes before sunrise; flight rules define night launch/landing as one
occurring no earlier than 15 minutes after sunset and no later than 15
minutes before sunrise.
Crew
List
Kevin
P. Chilton, Commander
Richard
A. Searfoss, Pilot
Linda
M. Godwin, Mission Specialist
Michael
R. Clifford, Mission Specialist
Ronald
M. Sega, Mission Specialist
NASA-2
Arrival
Shannon
W. Lucid, Mission Specialist
Crew
Biographies
Mission
Highlights
