Shuttle Discovery Prepares to Come Home

HOUSTON--Following a hectic week docked at the International Space Station (ISS) where a few historic "firsts" were performed in space, the shuttle Discovery is being prepared to come home.

"We're ready to go," said Paul Hill, Discovery's lead STS-114 flight director, during a briefing here at NASA's Johnson Space Center.

The only major concern, aside from the typical risks associated with flying the shuttle--effectively a 100-ton glider during reentry--back to Earth, is weather at Kennedy Space Center where it will land at 4:46 a.m. EDT ( 0846 GMT) Aug. 8, Hill said.

"We are highly confident in this entry," veteran astronaut Eileen Collins, Discovery's STS-114 commander, said earlier this week. "I think we're going to have a clean entry."

Discovery is set to undock from the ISS Saturday at 3:44 a.m. EDT (0744 GMT) then back about 400 feet away, where it will slowly circle the orbital laboratory with the station with shuttle pilot James Kelly at the helm.

"The only reason we're doing it is to take pictures of the space station," Hill said. "There's no technical reason other than the fact that we can see all the way around. We're going to take the time to snap some pictures from some angles we haven't seen since the last orbiter was there."

Discovery is the first shuttle to visit the space station since 2002, and NASA's first orbiter to fly since the Columbia disaster. Columbia's STS-107 mission, commanded by astronaut Rick Husband, ended in tragedy about 16 minutes before landing when the orbiter broke apart during reentry on Feb. 1, 2003 while flying over Texas. Investigators pinned the accident on wing damaged cause during Columbia's launch, when a piece of foam debris fell form the orbiter's external tank and pierced its heat shield.

Many of the new tools and methods used by Discovery's crew are a direct result of the Columbia accident.

The astronauts repeatedly used a laser camera-tipped inspection boom extension for the shuttle's robotic arm to scan their ship's thermal protection system, and ISS crewmembers photographed the orbiter's heat tile-covered belly during a backflip maneuver prior to docking on July 28.

The shuttle is now fit for landing after an in-flight repair to pluck two protruding strips of filler material from its belly tiles during a first-ever spacewalk and conclusions that a damaged thermal blanket should not pose a hazard during landing, the shuttle is fit for landing, mission managers said.

"But there is no such thing as no concern," Hill said. "Just making it past the milestone where we lost STS-107 is not enough."

Hill said that the lost Columbia astronauts have been a constant presence in his mind and those of his flight team, even as mission controllers focused on returning Discovery and its STS-114 crew home safely.

"During the crew commemoration yesterday, they were on our minds a lot," Hill said. "During de-orbit I'm sure I'll have a thought or two about Rick Husband and his crew. At wheel stop, I think a lot of us are going to think a lot about the STS-107 crew as well as the STS-114 crew at landing."

• Fixing NASA: Complete Coverage of Space Shuttle Return to Flight