Spacewalking astronauts out on 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 provides a stable platform for future
repair work on the U.S. space shuttle fleet.

British-born shuttle astronaut Piers Sellers and American
colleague Michael Fossum strapped their feet into a foot clamp
and dangled from the end of a 100-foot (30-meter) boom.

“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 if a shuttle is too damaged to return home.

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

Sellers and Fossum, who along with five other astronauts on
Discovery docked with the International Space Station on
Thursday, were to be out in space more than 6 hours. Their
spacewalk was the first of three on the shuttle’s 13-day
flight.

Before bouncing on the boom, they worked briefly on a
broken space station transport system needed to complete the
half-finished, $100 billion space outpost.

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

No major damage has been spotted on this flight, but
engineers are still studying filler material protruding
slightly from between heat-protecting tiles on the shuttle
skin.

If NASA decides to remove the protruding “gap fillers,” it
would likely happen on the third spacewalk, scheduled for
Wednesday.

Saturday’s work on the end of the boom was delayed slightly
by what the spacewalkers thought was a jammed safety tether. In
case the extension should break off the arm, NASA wanted the
astronauts to be tethered to the payload bay as a precaution.

But as the astronauts prepared to retrieve a spare tether,
flight directors asked them to double-check if the device was
unlocked.

“Oh, that’s pretty embarrassing,” Fossum said, realizing
their mistake and quickly moving the switch.

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.

As the two astronauts pretended to fix a damaged spaceship,
they appeared to be comfortable working at the end of the boom.
They ended their exercise at one of the station’s truss
segments, which they used as a stand-in heat shield to practice
applying putty and drilling and patching holes.

(Additional reporting by Jeff Franks)