Dinged-up Endeavour returns

The space shuttle Endeavour landed safely in Florida on Tuesday after completing a 13-day mission marred by damage to the spacecraft’s heat shield that led to a lengthy debate about whether to risk returning to Earth without fixing it.

The dinged-up spacecraft touched down at Cape Canaveral at 12:32 p.m. EDT after completing a 5.3-million-mile mission to the International Space Station.

NASA Administrator Michael D. Griffin said the damaged tiles “did very well on reentry.”

After examining the gouged thermal tiles on the tarmac at Kennedy Space Center in Florida, shuttle commander Scott Kelly said he was “a little bit underwhelmed by the size of the gouge. It looked rather small.”

Two heat-resistant tiles on the underside of the shuttle were damaged on launch by insulating foam that fell off the external fuel tank. The cavity concerned experts because it cut through almost to the aluminum skin of the shuttle.

NASA engineers spent days analyzing the damage before deciding not to send a repair team to squirt a caulk-like substance into the divot. Officials feared the repair could make the situation worse by changing the shape of the cavity, which could concentrate heat in the damage area, instead of limiting it.

Although a detailed analysis of the damaged tiles will be conducted, the tiles fared better than expected in the 2,300- degree heat of reentry, NASA said. There was some additional erosion around the tiles, but no indication the shuttle body was damaged.

Associate Administrator William H. Gerstenmaier said the incident would give NASA engineers more insight into how much damage shuttles can take and still land safely. “We are going to learn a lot from this,” he said.

Kelly said that dings and divots were just “part of the process of flying the space shuttle.” He said he agreed with the decision not to fix the damage and did not worry during reentry.

During the nearly two-week mission, Endeavour’s crew installed a new truss section on the station’s backbone, along with a storage bin and a new gyroscope to replace one that failed. Four gyroscopes keep the station properly aligned.

With the addition of the new truss section, the space station is 60% complete. “Little bit by little bit, we get the station built,” Griffin said. “It’s an awesome accomplishment.”

The mission was planned for 14 days, but the approach of Hurricane Dean in the vicinity of NASA’s ground control center in Houston caused mission managers to bring the crew home a day early.

Endeavour’s crew included Barbara Morgan, the backup on the Challenger mission to teacher Christa McAuliffe, who was killed along with her crew when the shuttle exploded during launch in 1986.

Before and during Endeavour’s mission, Morgan downplayed her ties to the doomed Challenger mission, saying little about it except that McAuliffe and the others were an inspiration.

As a newcomer in space, she admitted to feeling disoriented. She also had to get used to the idea that things inside the spacecraft and station don’t stay put, but tend to drift away.

After landing, she did not join the other crew members on the traditional walk-around to inspect the shuttle. Griffin said she felt “a little under the weather.”

Five hours later, Morgan had recovered enough to attend the crew news conference. “The room is still spinning a bit, but that’s OK,” she said.

Asked to describe her reaction to being in space, she said, “I’ve never seen anything that black.”

The next mission to the space station is scheduled for Oct. 23, but that could change as engineers examine the data from the damage to Endeavour’s heat shield. Cameras installed on shuttles after the loss of Columbia in 2003 have shown that on several recent missions, the insulating foam has come off of the same spot near a bracket that holds the fuel feed line in place.

The chunk of foam that damaged the underside of Endeavour first hit a strut, then ricocheted into the underside of the shuttle. In coming weeks, NASA will be conducting tests to see if that was an unlucky bounce or something more problematic.

The foam shedding is believed to be caused by a buildup of ice under the foam layer that insulates the tank. Ice forms because the liquid fuel that carries the shuttle to orbit is cooled to minus-420 degrees.

One potential cause of the ice buildup is the extra hour shuttles sit on the ground after fueling but before launch, added after the Columbia accident to give ground personnel time to find any late problems.

Engineers will be looking at cutting back on that hour to control ice.

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john.johnson@latimes.com