This story was updated at 12:33 p.m. EDT.
CAPE CANAVERAL, Fla. - Astronauts aboard NASA?s shuttle Discovery are gearing up for their planned Saturday landing after Mission Control found that a lost metal clip poses no threat to their spacecraft?s return.
Shuttle commander Mark Kelly and pilot Kenneth Ham test fired Discovery?s maneuvering thrusters and power up systems to flex the shuttle?s flight control surfaces. But after those tests, they reported spotting a shiny, rectangular bit of debris drifting away shuttle to the aft of its starboard wing.
Mission controllers swiftly studied the 1- to- 1 1/2-foot long (0.3-0.4 meter) object in short video of and still images captured by the shuttle crew. It was one of three tail-mounted metal clips that are not needed for landing and posed no threat to the orbiter?s planned landing.
?We?ve seen these things come off before and it?s really not a concern at all for entry,? Kelly said in a televised interview today. ?It?s no worry at all.?
Discovery?s crew is stowing last bits of cargo to prepare for tomorrow?s planned 11:15 a.m. EDT (1515 GMT) landing here at NASA?s Kennedy Space Center. Kelly and Ham are also rehearsing landing activities via a computer simulation.
?Overall, it?s a get ready for entry day,? NASA?s deputy shuttle program manager LeRoy Cain said Thursday, adding that the orbiter?s heat shield appeared to be in good health for landing.
Saturday homecoming ahead
Discovery?s six-man, one-woman crew is returning to Earth after a two-week mission to deliver Japan?s massive, billion-dollar Kibo laboratory to the International Space Station (ISS).
?That was pretty much solid work,? Ham said Thursday. ?We?re all pretty much tired at this point and getting ready to come home.?
Japan?s 37-foot (11-meter) laboratory is the size of a tour bus and the second segment of the Kibo research facility to reach orbit. It followed its small storage room, which astronauts delivered during an earlier mission in March.
The new room, the largest ever launched to the space station, includes two windows, a robotic arm and a small airlock for passing new experiments to a planned porch-like platform due to launch to the space station next year. A smaller robotic arm for fine movements is also slated to fly.
?It was just amazing,? said Discovery mission specialist Akihiko Hoshide, who helped install Kibo, of the view of his country?s new space lab during undocking Wednesday. ?I can?t really explain it.?
Returning to Earth with Kelly, Ham and Hoshide are mission specialists Karen Nyberg, Ronald Garan, Michael Fossum and returning station crewmember Garrett Reisman, who said he was awed at the sheer size of the now nearly three-quarters complete space station when Discovery undocked.
?It started out as just a single, little module, and now it?s enormous,? said Reisman, who is wrapping up a three-month spaceflight aboard the station and has compared its interior to the inside of a jumbo jet. ?With the addition of Kibo, it looks like a real space station, and that?s exciting.?
Reisman, a NASA astronaut, joined the station?s crew in March and was replaced by fellow U.S. spaceflyer Gregory Chamitoff, who arrived aboard Discovery last week to begin his own six-month mission.
Discovery astronauts will set up a special recumbent seat for Reisman today on the shuttle?s middeck that will allow the returning long-duration spaceflyer to return to Earth?s gravity in a reclining position, rather than the upright seats of the shuttle?s short-term flyers.
?The truth is, adjusting back to gravity is not so easy,? Reisman said during the mission. ?Just like adjusting to weightlessness takes some time, adjusting back to gravity takes some time too.?
Discovery has two chances to land Saturday with NASA?s Spaceflight Meteorology Group at the Johnson Space Center in Houston forecasting relatively fair conditions on landing day. Some clouds are expected during the shuttle?s first landing window, with a slight chance of rain showers within 30 miles (48 km) during a second opportunity at 12:50 p.m. EDT (1650 GMT).
Mission Control roused Discovery?s crew early Friday with the song ?Baby Won?t You Please Come Home? by Louis Prima and Keely Smith, a tune chosen for Reisman by his wife Simone.
?Good morning to you Houston and a special good morning to Simone, my favorite Earthling,? Reisman said. ?Get ready doll face, Discovery?s coming home.?
NASA is broadcasting the Discovery's STS-124 mission live on NASA TV. Click here for SPACE.com's shuttle mission updates and NASA TV feed.
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