STS-82 Day 5 Highlights
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- On Saturday, February 15, 1997, 7:00 a.m. CST, STS-82 MCC Status Report # 9
- Early this morning, astronauts Greg Harbaugh and Joe Tanner completed
a 7 hour, 27 minute spacewalk in the cargo bay of the Shuttle
Discovery to replace and install several new engineering components in
the Hubble Space Telescope.
- After being awakened late Friday afternoon, Harbaugh and Tanner
completed the checkout of their spacesuits well ahead of schedul,
allowing them to start the second spacewalk of the flight at 9:25
p.m. Central time, almost one hour ahead of schedule.
- Harbaugh and Tanner went right to work, replacing a degraded Fine
Guidance Sensor and a failed Engineering and Science Tape Recorder
with new spares. Payload controllers verified that the new Fine
Guidance Sensor and the new tape recorder were healthy and ready to
support the telescope's scientific efforts. The astronauts also
installed a new unit known as the Optical Control Electronics
Enhancement Kit, which will further increase the capability of the new
Fine Guidance Sensor.
- During the spacewalk, the astronauts and flight controllers took note
of cracking and wear incurred by thermal insulation which protects
several areas of the telescope. The part of the telescope which is in
the direction of travel and always exposed to the sun has experienced
slight cracks and delamination during almost seven years of time on
orbit. Flight controllers and Hubble project managers are evaluating
whether some repair work might be performed to certain portions of the
telescope's insulation during the final spacewalks of the flight.
- As Harbaugh and Tanner neared the end of their work in the cargo
bay, Discovery's small maneuvering jets were fired for about 20
minutes to gently raise Hubble's altitude by about 1.8 nautical miles.
The reboost effort by Commander Ken Bowersox and Pilot Scott Horowitz
will be performed again near the end of the final two spacewalks and
should raise Hubble's altitude by a total of about five nautical
miles. Harbaugh and Tanner returned to Discovery's airlock at 4:52
A.M., with more than 14 hours of spacewalk servicing time having been
logged during the first two excursions in the Shuttle's cargo bay.
- The astronauts will begin an eight-hour sleep period at 9:25 this
morning and will be awakened at 5:25 this afternoon for the third
spacewalk by Mark Lee and Steve Smith. They will replace an ailing
Data Interface Unit, swap out another science and engineering tape
recorder for a new solid state recorder and will replace a faulty
Reaction Wheel Assembly for a new unit to help steer the telescope to
- Discovery and the Hubble Space Telescope continue to orbit the Earth
every 90 minutes at an altitude of approximately 370 statute miles
with all of the Shuttle's systems still operating in excellent
- On Saturday, February 15, 1997, 5:00 p.m. CST, STS-82 MCC Status Report # 10
- With two spacewalks complete, the STS-82 crew has met the minimum
success criteria for the second Hubble Space Telescope servicing
mission, but still has plenty of work left to do.
- Tonight, astronauts Mark Lee and Steve Smith will leave the crew
cabin for their second spacewalk of the flight. Lee and Smith are
scheduled to install a new Data Interface Unit in HST and swap out a
science and engineering tape recorder with a new solid state
recorder. Unlike the older reel-to-reel recorder, the new digital
recorder has no reels, no tape or moving parts to wear out and
unlimited lifetime. Data is digitally stored in computer-like memory
chips until HST's operators at the Goddard Space Flight Center play it
back. Lee and Smith also will replace a Reaction Wheel Assembly that
failed late last year with a new unit to help steer the telescope to
- The Hubble Space Telescope was designed for on-orbit servicing with
three maintenance scenarios in mind. They are incorporating
technological advances into the science instruments as was done with
the installation of the Space Telescope Imaging Spectrograph and the
Near Infrared Camera and Multi-Object Spectrometer, replacing items
such as the tape recorders and reaction wheels which normally degrade
over time; and correcting random equipment failures or malfunctions.
- If there is time during the spacewalk, Lee and Smith may perform
some simple operations to assist engineers in planning for the
possibility of performing some repairs to the aging thermal covering
of the telescope. Controllers and astronauts have noticed areas on the
telescope where the insulation is peeling. The tasks include bringing
materials that could be used for the repair back into the crew cabin,
assessing how brittle the insulation is and testing how well Kapton
tape adheres to the insulation.
- The spacewalk is officially scheduled to begin at 10:20 p.m., but
for the first two EVAs, crew members completed their preparations
early so that they were ready to begin between 9 and 9:30 p.m.
- Also during the sixth day of the mission, Commander Ken Bowersox and
Pilot Scott Horowitz will fire the small steering jets in the next
phase of the effort to reboost the telescope. The first reboost burn
raised Hubble's altitude by about 1.8 nautical miles, and a second
unplanned burn, which was required to move Discovery a safe distance
from some orbital debris, raised the orbit another half mile. Overall,
flight controllers plan to raise HST's orbit about 7 statute miles.
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