NASA delays decision on shuttle repair

NASA was leaning against repairing damage to Endeavour’s heat shield after lab tests and engineering analyses indicated the shuttle could safely fly home next week, officials said Wednesday.

Shuttle deputy program manager John Shannon said mission managers would wait for one last heat test before making a final decision today.

“We’re pondering. But my personal feeling is, the data is 80% to 90% that we can use” the shuttle as is, Shannon said at a briefing Wednesday evening at Johnson Space Center in Houston.

The fear is that in trying an in-space repair, astronauts could make the situation worse. NASA has never attempted such a repair on the underside of the shuttle, and much of the work would be done out of sight of ground controllers.

“I am cautiously optimistic that repairs will not be needed,” Shannon said.

Endeavour was damaged during launch Aug. 8 by a chunk of foam that broke off the external fuel tank, ricocheted off a strut and hit the orbiter near the right main landing-gear door.

The foam tore off a 3-inch-wide portion of two of the silica tiles that protect the shuttle from the 2,300-degree heat of re-entry. The damage extends nearly to the shuttle’s aluminum body, which could start melting at 1,200 degrees.

Over the weekend and again Tuesday, engineers analyzed the damage to see whether high temperatures could endanger the shuttle and its seven-person crew.

Every test, Shannon said, indicated the shuttle could return safely without endangering the vehicle. Even if the aluminum skin were damaged during reentry, the gash is not in a sensitive area.

Endeavour carries three repair kits on board; one, a protective screw-on plate, has been eliminated as a possible solution. The preferred technique would be to send two astronauts on a spacewalk to the underside of the shuttle to apply a paint-like wash and a substance called “the goo.”

The goo, formally known as STA 54, would be applied with a device similar to a caulk gun.

However, NASA engineers are worried that in the microgravity environment of the Space Station, where the shuttle is docked, the gun might not work as expected.

Also, smooth aerodynamic flow is crucial during reentry, and NASA is hesitant to try anything that could interfere with it.

Managers on Wednesday also cut short the third spacewalk of the mission when astronaut Richard A. Mastracchio’s right glove was torn. It was the first time a shuttle spacewalk was cut short because of such a problem.

Analysts are unsure whether the damage was caused by a sharp edge on the space station or by wear. The glove contains several layers of protection, and Mastracchio was never in danger, officials said.

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john.johnson@latimes.com