Shuttle crew spacewalks, tests repair methods

By Irene Klotz and Jeff Franks

HOUSTON (Reuters) – Two shuttle Discovery astronauts
completed a seven-hour spacewalk on Saturday to restore a
critical steering device on the International Space Station and
test shuttle heat shield repairs that NASA hopes will prevent
another Columbia disaster.

“What a view,” Japan’s Soichi Noguchi said as he drifted
out of Discovery’s airlock into the open payload bay and looked
down on Southeast Asia 224 miles below.

“Yeah, it’s been a long road,” said spacewalking partner
and U.S. astronaut Steve Robinson.

The spacewalk was NASA’s first at the International Space
Station since November 2002.

After taking a few minutes to acclimatize to the vastness
of open space, Noguchi and Robinson, both first time
spacewalkers, used a specially designed caulking gun and putty
knives to try to repair sample shuttle heat shield tiles and
wing panels that had been purposefully damaged.

The astronauts worked only on the sample materials in the
payload bay and did not touch any of the minor damage caused
during liftoff to Discovery’s heat shield, which is believed to
be in good shape for landing.

NASA lost shuttle Columbia and its seven astronauts during
the last landing attempt on Feb. 1, 2003. The ship’s wing had
been damaged during launch by falling debris and as the shuttle
sailed through the atmosphere for landing, hot gases blasted
inside the hole, tearing the ship apart as it flew over Texas.

Robinson got to work first, squeezing out thick black beads
of a heat-resistant product called NOAX, then working the
material into cracks and gouges in the sample wing panel.

‘PIZZA DOUGH’

“I see just a little bit of bubbling,” he said. “It’s about
like pizza dough.”

Noguchi then used another device similar to a shoe polish
applicator to dab a material, known as an emittance wash, on to
damaged heat-shield tile samples.

Engineers will study the repaired sample tiles and wing
panels after the shuttle returns to Earth.

Noguchi replaced a broken Global Positioning System antenna
on the space station, which is used by the orbiting structure’s
computers to help determine its exact location.

The spacewalkers also swapped a power cable to fix a backup
gyroscope which had failed in March. The gyroscope is one of
four that keep the station properly positioned without using
the station’s limited supply of fuel for rocket thrusters.

The astronauts will replace another failed gyroscope during
their next spacewalk, scheduled for Monday.

After sailing through all their assigned tasks, the
astronauts had some extra time to retrieve two materials
science experiments from outside a station airlock.

They also photographed some areas of damage on the shuttle
that engineers want more information about while crew members
in the shuttle carried out an additional unscheduled scan of
Discovery’s left wing with a special boom.

In addition to servicing the station, Discovery’s flight
was designed to test dozens of post-Columbia safety upgrades.
NASA’s biggest change — a redesign of the shuttle’s fuel tank
so that it would not shed foam during launch — failed its
first test-flight, prompting NASA to again ground the remaining
shuttle fleet until additional repairs can be made.

Discovery is scheduled to return from space on Aug. 7, but
NASA managers said they may extend the mission a day to
transfer more supplies to the space station, just in case the
next visit by a shuttle is some time down the road.