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Discovery crew may have to repair shuttle

July 31, 2005

By Irene Klotz

HOUSTON (Reuters) – NASA is trying to determine if two bits
of material sticking up from the shuttle Discovery’s thermal
tiles present an unacceptable risk of overheating when the
shuttle returns to Earth, the flight director said on Sunday.

The space agency is working on plans for spacewalkers to
fix the parts if engineers decide they pose a threat to the
first shuttle mission since the 2003 Columbia accident, said
Flight Director Paul Hill.

NASA managers already have deemed 90 percent of Discovery’s
heat shield able to withstand the tremendous forces and high
heat of atmospheric re-entry on Aug. 8.

But NASA has discovered two protruding gap fillers, which
is material used to fill any minute gaps between heat shield
tiles. A decision about whether the crew will be asked to fix
them is expected on Monday, Hill said.

“We have a team of folks working aggressively at options to
go and make that gap filler safe if we decide it’s an issue,”
said Hill at a news conference.

The protruding parts of Discovery’s heat shield are not the
result of debris impacts, which damaged Columbia’s heat shield
and caused it to break up over Texas on Feb. 1, 2003.

Seven astronauts died in the accident, prompting a major
safety overhaul. But large bits of debris still came off
Discovery’s fuel tank when it blasted off, prompting NASA to
ground the entire shuttle fleet.

CONCERN OVER GAP FILLER

Now there is concern that the protruding gap filler could
generate extreme heat that would make the shuttle’s belly,
where there may be some minor damage caused by debris, more
vulnerable on re-entry.

NASA is now targeting Discovery’s landing for Aug. 8, a day
later than planned so that the crew will have more time to
finish transferring equipment to the orbiting space station,
which likely will be without shuttle servicing missions for a
while.

Repair options include removing the protruding fillers,
tacking them back down or trimming them, Hill said.

Any work would be done by shuttle Discovery’s two trained
spacewalkers, Soichi Noguchi of Japan and NASA’s Steve
Robinson. They completed the first of three planned outings on
Saturday and their second spacewalk to replace a failed
steering device on the space station was scheduled for Monday.

Hill said there was a remote possibility the crew would be
asked to make an unplanned fourth spacewalk on Friday to work
on the gap fillers. However, it was more likely they would do
the work during their third spacewalk on Wednesday, if it
became necessary, he said.

The astronauts spent Sunday transferring about 15 tons of
equipment and supplies to the space station and preparing for
Monday’s spacewalk.

In television interviews from the shuttle, the Discovery
crew expressed confidence they would return safely.

“From all indications, it looks like it’s a clean vehicle
and we’re good to go to return home,” said mission specialist
Charles Camarda.

(Additional reporting by Jeff Franks)




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