STS-82
Report # 10 
 Saturday, February 15, 1997, 5 p.m. CST 
 
 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
its targets.

  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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