August 2, 2005
Spacewalk sounds scarier than it is, NASA says
By Irene Klotz
HOUSTON (Reuters) - The shuttle Discovery's crew had
misgivings about performing a spacewalk to remove two fabric
fillers dangling from the ship's delicate heat shield,
astronauts said on Tuesday.
However, the more the astronauts who are flying NASA's
first mission since the 2003 Columbia disaster learned about
the plan, the more comfortable they became with the unexpected
-- and unprecedented -- repair.
Spacewalker Stephen Robinson planned to go beneath the
shuttle Wednesday to pluck out two pieces of ceramic-coated
cloth sticking out from the ship's smooth, tiled belly.
"Like most kinds of repairs, it's conceptually very simple,
but it has to be done very, very carefully," Robinson said
during a news conference from space.
The protruding strips are only an inch (2.5 cm) long but
NASA fears they could affect how air flows over the orbiter and
dangerously add to the intense heat as the ship re-enters
Earth's atmosphere at 17,000 mph (27,200 kph).
The primary risk of removing or cutting the strips is that
Robinson could inadvertently damage the surrounding tiles that
are made to resist that heat, but not an accidental knock from
a space helmet.
The crew took a break from spacewalk preparations to take a
call from President Bush.
"I just wanted to tell you how proud the American people
are of our astronauts," Bush said. "I want to thank you for
being risk-takers for the sake of exploration."
Robinson, who along with Soichi Noguchi has already made
two spacewalks on the mission, will become the first astronaut
in the 24-year shuttle program to venture beneath one of the
ships in space. He will be strapped to the station's robot arm
and watched by television cameras, so the spacewalk "sounds
scarier than it is," flight director Paul Hill said.
NASA ordered the repair because it fears another heat
shield failure, such as the one that claimed Columbia and its
seven-member crew in February 2003.
"I think a number of us, we did have some misgivings," said
astronaut Andy Thomas of Australia. "We were concerned about
the implications of it and what was motivating it."
Mission specialist Charles Camarda said if pulling out the
protruding material, called gap filler, lessens the risk of
overheating during re-entry, the mission was worth the risk.
"It's a very close call," he said during the news
Robinson said his biggest concern will be to avoid butting
the shuttle tiles with his helmet.
"The tiles, as we all know, are fragile and a crewmember
out there is pretty large mass," Robinson said. "The thing I'll
be watching most closely is the top of my helmet because I'll
be leaning in toward the orbiter. So that's what I'll be most
Discovery is docked to the International Space Station and
orbiting 220 miles above Earth. Robinson's repair mission was
tacked on to an already scheduled spacewalk to attach a storage
platform to the station.
Robinson will be maneuvered to the shuttle's belly on the
space station's robot arm, then will try to pluck the thin,
ceramic-covered strips out with his gloved fingers.
If that fails, he will tug at them with forceps and if that
does not work he will try to saw them off with a modified
"There won't be yanking going on. It will be a gentle pull
with my hand. The main tools I plan to use are right here," he
said, holding out his hand and pinching his fingers together.
Columbia's demise was caused by a hole in the ship's wing
panels that was hit by a piece of foam insulation that fell off
the fuel tank during launch.
Superheated gases entered the breach during re-entry and
the shuttle broke apart over Texas.
Videos showed loose tank foam at Discovery's launch last
week, which prompted NASA to ground the shuttle fleet.