(AP) -- Shuttle Discovery's astronauts aimed for a Thursday evening landing to wrap up their successful space station delivery mission, but late summer storms threatened to keep them up an extra day or two.
Mission Control said Wednesday that "the weather will pose a challenge" for bringing Discovery home. The forecast called for a chance of thunderstorms. Conditions were expected to worsen Friday and remain poor Saturday.
"The weather in Florida this time of year is always a little iffy," Discovery's commander, Rick Sturckow, said from orbit. "If things aren't good, the worst that can come out of it is that we have another day in space, which is a great deal."
In orbit since Aug. 29, Discovery has enough supplies to last until Sunday. If the shuttle cannot return to Florida on Thursday, NASA will consider landing it in California, but not until Friday at the earliest.
Astronaut Timothy Kopra is headed home after nearly two months at the international space station. He said the flight wasn't too long by any stretch. He should have spent an extra month at the outpost, but his ride up ended up being delayed because of shuttle problems.
Buzz Lightyear, by comparison, spent 15 months aboard the space station.
The 12-inch action figure rocketed into "infinity and beyond" aboard Discovery in May 2008. Once Walt Disney World gets the toy back, it will be feted at a tickertape parade early next month with Buzz Aldrin, the second man to walk on the moon.
Kopra assured a TV interviewer that Buzz is doing well after so long in space.
"He's very secure. He's in his spacesuit, and I'm quite confident that he'll have a very safe ride home. But we obviously cannot disclose his location upon the space shuttle," Kopra joked. He kept a serious face, but his crewmates chuckled.
Sturckow and his crew spent Wednesday checking their flight systems to make sure everything was in order for re-entry. While that was happening, a small object resembling a strip of cloth floated away from the left side of the shuttle, back along the payload bay.
Mission Control assured the astronauts that while no one could identify the piece, it was not part of the shuttle's thermal shielding and posed no safety concern for re-entry.
Columbia was destroyed during re-entry in 2003 because of a gashed wing. It wasn't until later that a space surveillance review discovered an object floating away from Columbia on flight day two; experts believe it was part of a wing panel.
Thanks to restocking by Discovery, the space station now has enough food to last until February, as well as a spare air-cleanser and new treadmill. The exercise machine is named Colbert in honor of the TV comedian. More supplies will arrive on a Japanese vessel that's due to lift off Thursday, just before Discovery's scheduled 7:05 p.m. touchdown.
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