- The Washington Times - Tuesday, August 14, 2007

CAPE CANAVERAL, Fla. (AP) — NASA conducted a swift series of tests on the ground yesterday to determine whether a disturbingly deep gouge in the Space Shuttle Endeavour’s belly needs to be fixed for re-entry as a pair of spacewalking astronauts replaced a broken space station steering device.

The gouge is relatively small — 3½ inches by 2 inches — but part of it penetrates through the protective thermal tiles, leaving just a thin layer of felt material over the shuttle’s aluminum frame to keep out the more than 2,000-degree heat of re-entry.

Mission managers expect to decide by today whether astronauts should go out and patch the gouge or whether the damage is benign enough for Endeavour to fly home safely.

NASA has never attempted this type of emergency repair on an orbiting shuttle, and two of the three remedies — all developed after Columbia’s catastrophic re-entry — are untested in space. As in Columbia’s case four years ago, Endeavour’s gouge resulted from a piece of foam striking the shuttle at liftoff.

Despite extensive redesigning of the shuttle fuel tank that has already cost NASA a few hundred million dollars, foam has repeatedly fallen off the tank during launch, although nothing nearly as big as the piece that crippled Columbia.

Depending on how NASA addresses the latest foam problem, space shuttle flights could come to a temporary halt, stalling construction at the International Space Station once more.

To patch the gouge, spacewalking astronauts would have to perch on the end of the shuttle’s 100-foot robotic arm and extension boom, be maneuvered under the spacecraft, and either apply black paint, screw on a protective plate or squirt in goo.

The black coating, intended to help dissipate heat, was tested on a previous shuttle flight. The two other repair methods have been tested in vacuum chambers on Earth, but never in space.

Yesterday’s spacewalk, on the other hand, was comparatively routine.

Shuttle astronauts Rich Mastracchio and Dave Williams ventured outside for the second time in three days, removing a 600-plus-pound gyroscope from the space station’s exterior that failed in October. They installed a new one in its place that was carried aboard Endeavour. The space station has four gyroscopes to keep it steady and pointed in the right direction.

Teacher-astronaut Barbara Morgan — Christa McAuliffe’s backup for Challenger’s doomed mission in 1986 — helped monitor the spacewalk from inside the joined shuttle-station complex.

Even before Endeavour’s liftoff, NASA was planning a third spacewalk for tomorrow and a fourth for Friday to carry out more space station work. Any shuttle repairs, if ordered, would take place on one of those two outings. The shuttle isn’t due to leave the station until next week; landing is set for Aug. 22.