Spacewalking astronauts out on a limb

By Irene Klotz

HOUSTON (Reuters) – Two spacewalking astronauts spent
Saturday twisting and bending at the end of a spindly pole to
make sure the device could provide a stable platform for repair
work on U.S. space shuttles.

British-born shuttle astronaut Piers Sellers and American
Michael Fossum took turns strapping their feet onto a small
platform and dangling from the end of a 100-foot (30-meter)
boom that would allow astronauts to reach every part of a
shuttle.

“It’s like being in a very slow elevator,” Sellers radioed
to ground controllers as he rode atop the end of the boom,
which is a combination of the space shuttle Discovery’s 50-foot
(15-meter) robot arm and a 50-foot (15-meter) extension.

The exercise, performed at 17,500 miles per hour (28,000
kph), 220 miles above the Earth, was part of NASA’s efforts to
recover from the 2003 Columbia disaster and make certain there
are options for repairing a damaged shuttle before it returns.

Seven astronauts aboard Columbia died without knowing their
shuttle was critically damaged when insulation foam fell off
during liftoff. The vessel broke apart over Texas as it
returned to Earth.

“Hopefully we never have to use it but we have the
capability if we ever need to,” flight director Tony Ceccacci
said after the test with the boom ended.

Sellers and Fossum, who along with five other astronauts on
Discovery docked with the International Space Station on
Thursday, spent more than seven hours outside the ship.

The spacewalk, which is the first of three planned during
the shuttle’s 13-day flight, was extended an hour due to
difficulties with safety tethers, which are used to keep tools
and the astronauts from floating off into space.

ORBITAL SUNRISE

One problem was quickly resolved when flight controllers
asked if a tether retraction switch was unlocked.

“Oh, that’s pretty embarrassing,” Fossum said, realizing
their mistake and unlocking his tether.

The moonlit Earth appeared over the shuttle’s left wing and
the astronauts quickly regained their composure. An orbital
sunrise hit them full face.

“That’s so beautiful,” Fossum said.

The two astronauts, who had earlier worked on a broken
space station transport system needed to complete the
half-finished, $100 billion space outpost, appeared comfortable
at the end of the boom, simulating fixing a damaged spaceship.

Since Discovery’s launch from Florida on Tuesday, NASA has
been poring over the shuttle with cameras and sensors looking
for any damage.

On the only other post-Columbia shuttle flight, which flew
last summer, foam also fell off the fuel tank at launch, but
did not harm the spacecraft. NASA has spent $1.3 billion on
safety upgrades since the Columbia disaster.

No major damage has been spotted on this flight, but
engineers are still studying one area where filler material is
protruding slightly from between heat-protecting tiles.

If NASA decides to remove the protruding “gap filler,” it
would likely be attempted on the third spacewalk on Wednesday.

Being able to use a boom for repairs also boosts the chance
NASA will approve a servicing mission to the Hubble Space
Telescope, said shuttle deputy program manager John Shannon.

Crews flying to Hubble would not be able to reach the space
station to await rescue if their ship was damaged during
flight. Instead, they would have to attempt repairs.

(Additional reporting by Jeff Franks)