Shuttle Endeavour's Heat Shield Cleared of Concerns
The International Space Station's new Tranquility module is moved to the port side of the Unity node on the station during an overnight spacewalk that began Feb. 10, 2010 on NASA's STS-130 mission.
Credit: NASA.

The space shuttle Endeavour?s heat shield is in fine shape despite three minor defects, which pose no risk to the orbiter or its six-astronaut crew, a top NASA official said Friday.

Deputy space shuttle program manager LeRoy Cain said engineers have cleared Endeavour for its planned re-entry and landing late next week after settling concerns over two protruding bits and a cracked thermal tile.

Images of Endeavour before it arrived at the International Space Station this week revealed a small ceramic insert jutting up from just below a cockpit window. A small crack in a white heat-resistant tile on the cockpit?s roof also had reappeared and part of a small seal on the shuttle?s left wing had peeled up.

None of the items posed a major safety concern, and all are too small to cause any damage to Endeavour if they rip off under the searing heat of re-entry, said Cain, who leads Endeavour?s mission management team.

Cain told reporters that NASA engineers had ?reviewed all of that data and we determined that the vehicle is cleared for safe deorbit, re-entry and landing.?

NASA has kept a close watch on shuttle heat shield health since a piece of debris led to the destruction of shuttle Columbia during re-entry in 2003. A final, standard inspection of Endeavour?s heat shield will be conducted by shuttle astronauts once the orbiter leaves the station next week.

Tranquility in space

With Endeavour?s heat shield in the clear, all 11 astronauts aboard the linked shuttle and space station can focus on opening the orbiting laboratory?s brand-new room and fixing a finicky spacesuit fan for a late Saturday spacewalk.

The new space room, called Tranquility in honor of the Apollo 11 landing site, was attached to the station during an overnight spacewalk that began late Thursday.

The module is nearly 24 feet (7 meters) long and about the size of a small bus. The plumbing lines for its main cooling system haven?t been hooked up yet, so astronauts can?t switch on all of its systems.

But they can open the hatch to the module and begin outfitting it for use on the space station.

That grand opening is slated to take place tonight at 9:14 p.m. EST (0214 Saturday GMT).

?Today we ingress the new module and get it up and running. Great to have everybody on board!? station commander Jeffrey Williams wrote in a Twitter update. He leads the station?s five-man crew.

The astronauts are expected to open Tranquility?s door and move a bulky bench press-like exercise machine inside as one of their main tasks. They will have to use hand-held flashlights since the module?s main systems aren?t online.

Tranquility was delivered with a seven-window observation deck that includes a huge round central window that is the largest ever sent to space. ?Those windows are closed tight and covered by protective shutters, but will be opened next week once the observation dome is moved to its final, Earth-facing location.

The two additions cost nearly $409 million and were built in Italy for NASA by the European Space Agency. They?re arrival has brought the $100 billion space station up to 98 percent complete, but three spacewalks are required to fully install them.

The spacesuit glitch, the second for Endeavour?s two-man spacewalking team, will require astronaut Nicholas Patrick to fix a malfunctioning fan inside his suit. He may replace the small parts or use a different suit entirely, but only after the power harness on that spare can be repaired, mission managers said.

Next shuttle?s move delayed

Meanwhile, engineers back on Earth have delayed plans to move Endeavour?s sister ship Discovery to NASA?s cavernous Vehicle Assembly Building in Florida to be attached to its external fuel tank and rocket boosters.

Frigid temperatures will keep that shuttle in its maintenance hangar at the Kennedy Space Center until at least Monday. When temperatures drop to around 30 degrees Fahrenheit (minus 1 degrees Celsius) the seals on a shuttle?s thrusters can leak, among other issues, Cain said.

Discovery is slated to launch a cargo pod filled with supplies and equipment to the space station on March 18. It is one of NASA?s five final shuttle flights (including Endeavour?s current one) before the three-orbiter fleet is retired this fall.

Cain said shuttle managers will wait to see if the cold snap in Florida breaks next week before deciding what impact Discovery?s delayed move, if any, will have on its upcoming launch date.

SPACE.com is providing complete coverage of Endeavour's STS-130 mission to the International Space Station with Managing Editor Tariq Malik and Staff Writer Clara Moskowitz based in New York. Click here for shuttle mission updates and a link to NASA TV.