NASA Mulls Spacewalk Repair for Shuttle Tile Damage

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.

• VIDEO: STS-118 Mission Profile: Station-to-Shuttle Power Transfer
• VIDEO: Teaching the Future: Teacher-Astronaut Barbara Morgan
• Complete Space Shuttle Mission Coverage