CAPE CANAVERAL - NASA plans
to add a fifth spacewalk to shuttle Discovery's upcoming mission so astronauts
can practice repairing the type of heat-shield damage done to Endeavour on a
flight last month.
Discovery mission
specialists Scott Parazynski and Douglas Wheelock aim to use a device similar
to a caulk gun to repair thermal tile samples that have been deliberately
damaged.
NASA engineers developed
the Tile
Repair Ablator Dispenser, or T-RAD, as part of a post-Columbia effort to
give astronauts a way to repair damage to the thousands of thermal tiles that
line the underside of the shuttle orbiter.
The device is designed to dispense
a putty-like material to fill dents and gouges in the fragile tiles. Also
known as the "goo gun," it has never been tested in space.
The development of
heat-shield repair tools and techniques was recommended by the Columbia
Accident Investigation Board.
NASA planned to test the
device on a mission next year. Plans to move up the spacewalk demo were laid
after a chunk of foam the size of a baseball dug
a deep gouge in tiles on Endeavour last month.
NASA managers considered
using the T-RAD device to repair the tiles, but ground tests and engineering
analyses showed the shuttle would come through atmospheric re-entry without
significant damage. The analyses proved correct.
A special stowage bin for
the goo gun and tile samples was installed in the cargo bay of Discovery
earlier this week. The shuttle's payload bay doors, which already had been
closed for flight, were reopened so the Tool Stowage Assembly could be attached
to the starboard sidewall of the orbiter.
Kyle Herring, a spokesman
for NASA's Johnson Space Center, said the extra spacewalk is expected to be
officially added to the mission during a joint meeting next Monday between
managers of the shuttle and International Space Station programs.
It will lengthen the
upcoming mission to 13 days rather than 12 and will equal the greatest number
of spacewalks ever carried out on a shuttle flight. The only other missions to
feature five spacewalks have been Hubble Space Telescope servicing flights.
One of the spacewalks to be
done on Discovery's stay at the station will be carried out by outpost
commander Peggy Whitson and flight engineer Yuri Malenchenko rather than the
shuttle crew.
Discovery is scheduled to
launch Oct. 23 with the U.S. Harmony
module, which will serve as the gateway to still-to-be-launched European
and Japanese science laboratories.
The orbiter is slated to
roll over to the Kennedy Space Center Vehicle Assembly Building from Bay No. 3
of the Orbiter Processing Facility on Sept. 19.
The fully assembled shuttle
is scheduled to roll out to launch pad 39A on Sept. 27.
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