HOUSTON -- NASA
engineers are analyzing a small, but deep, gouge in the belly-mounted tiles on
the space shuttle Endeavour to determine whether astronauts will have to repair
the damage in a spacewalk, mission managers said Sunday.
The gouge, which
Endeavour astronauts scrutinized
earlier today with a laser-tipped inspection boom, runs all the way through a
1.12-inch (2.8-centimeter) thick tile on the shuttle's undercarriage exposing a
small bit of felt filler material underneath, John Shannon, NASA's deputy
shuttle program manager, in a briefing here at the Johnson Space Center (JSC).
"I
don't have an idea of whether a repair will be required," said Shannon,
who chairs Endeavour's mission management team. "But if we do, we'll
address that and I have full confidence that if one is required, we'll go
execute it."
Shannon
said analysts have refined their estimates of the fuel
tank foam debris that carved the gouge into Endeavour's underbelly
58 seconds after the orbiter's Aug. 8 launch.
It was a
baseball-sized chunk of foam, slightly smaller than earlier, grapefruit-sized
estimates, that fell from a bracket on Endeavour's fuel tank, then ricocheted
off a metal strut into the tiles about four feet (1.2 meters) from the
spacecraft's right landing gear door. After the initial hit, the foam scraped
along Endeavour's aft leaving several secondary dings that were later found to
be of no concern, NASA said.
"The
primary concern is on the main gouge there that goes all through the thickness of
the tile," Shannon said.
Deep
damage
The foam
damage etched a 3 1/2-inch by 2-inch (9-centimeter by 5-centimeter) gash across
two tiles on Endeavour's belly. The damage left a tiny area of about 0.2-inch
by 1-inch (0.5-centimeter by 2.5-centimeter) bare of any heat-resistant tile
material, Shannon said.
In a bit of
luck, the damage occurred right underneath a spot on Endeavour's wing that includes
a metal rib, which also lends additional heat resistance to the local area, he added.
NASA has kept
a watchful eye on shuttle fuel tank foam debris and the integrity of its
orbiters' heat shields since the 2003
Columbia accident. A 1.67-pound (0.75-kilogram) chunk of foam breached
Columbia's left wing during launch, leading to the loss of the orbiter and its
seven-astronaut crew during reentry.
Since then,
NASA has redesigned shuttle fuel tanks to minimize foam debris and instituted
mandatory in-flight heat shield inspections for orbiter crews.
Shannon
said engineers will use the detailed images and laser data collected on the gouge
during Sunday's focused inspection to build a three-dimensional model of the
damaged tile.
They will
then run it through computer simulations Monday to study its thermal properties.
Physical mockups of the damage will be also be tested in NASA's arcjet facility
here at JSC, where they will be subjected the same extreme temperatures
Endeavour will experience during reentry and landing.
Teacher-turned-astronaut
Barbara Morgan, who originally served as NASA's Teacher in Space for
Christa McAuliffe before the 1986 Challenger accident, helped survey the gouge
in Endeavour's underbelly with the shuttle's inspection boom Sunday with
shuttle crewmate Tracy Caldwell.
Extended
mission
While engineers
analyze Endeavour's tile damage, mission managers also decided Sunday to extend
the shuttle's construction flight to the International Space Station (ISS) by
three extra days.
The
extension is due to the success of a new Station-to-Shuttle
Power Transfer System that allows Endeavour to siphon electricity from the space
station's solar power grid to conserve its own fuel cell-driven resources.
The Boeing-built
system was activated just after Endeavour docked at the ISS on Friday and has
been feeding the shuttle an average of six kilowatts, except during spacewalks
when the available power was a bit lower.
"It's
still behaving just perfectly," Matt Abbott, NASA's STS-118 mission lead
shuttle flight director, said of the new system.
Initially
slated for an 11-day spaceflight, Endeavour's STS-118 crew will now remain in
orbit for about 14 days, 10 of them aboard the ISS for a record shuttle visit, NASA
has said.
The extra
time will allow Endeavour's crew to perform an extra, fourth spacewalk and
should allow Morgan to take part in up to three interactive video events with
students on Earth, NASA has said.
NASA is
broadcasting Endeavour's STS-118 mission live on NASA TV. Click here for mission updates and
SPACE.com's NASA TV feed.
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