Final day in orbit for space shuttle Atlantis

The six astronauts flying aboard space shuttle Atlantis worked Tuesday to prepare their spacecraft for its final planned return to Earth.

STS-132 mission commander Ken Ham, pilot Dominic "Tony" Antonelli and mission specialists Garrett Reisman, Piers Sellers, Stephen Bowen and Michael Good spent their morning packing supplies, stowing equipment and testing Atlantis' flight control systems, all in an effort to bring the shuttle to a landing at NASA's Kennedy Space Center (KSC) in Florida on Wednesday. Their first opportunity to land, weather permitting, is targeted for 8:48 a.m. EDT (1248 GMT).

"The crew will power up one of the auxiliary power units that provide its hydraulic power to the aerosurfaces on Atlantis and they will check those out along with some navigational aids that are used to find the landing site," described lead shuttle flight director Mike Sarafin on Monday. "Once those are complete, the crew will proceed into some cabin stow activities and Atlantis will be ready to come home."

IN PICTURES: NASA's Space Shuttle

"The crew is doing exceedingly well and we all look forward if all goes well, to the return of Atlantis to the Kennedy Space Center," Sarafin added.

In addition to the astronauts on-orbit landing preparations, mission managers were also waiting on the results from a survey that the astronauts performed on Monday using the shuttle's robotic arm and extension boom to inspect Atlantis' heat shield for orbital debris damage.

"We expect an answer by the crew's midday meal or early-to-mid-morning Houston time, and once we get that answer, the final clearance for reentry will be given relative to Atlantis' heat shield," said Sarafin.

With Mission Control optimistic that the shuttle will be cleared, their attention has begun turning to the only other factor that could delay Atlantis' return: weather conditions at NASA's east coast spaceport.

"The early weather forecast at the Kennedy Space Center is typical for a spring attempt," Sarafin said. "There is a chance of low clouds and a chance of showers."

Atlantis launched May 14 and has enough supplies to stay in orbit through Saturday. NASA has planned two landing attempts into KSC on Wednesday and two more on Thursday before calling up back-up sites at Edwards Air Force Base in California and in White Sands, New Mexico.

"We may get lucky and land on the first attempt and the weather may cooperate, or we may have to go around another day or two. We'll just have to see how that plays out," Sarafin said.

Other activities scheduled for today aboard Atlantis included the astronauts stowing the high bandwidth antenna through which they have been relaying live and recorded video, as well as exercise sessions to help prepare the crew for their return to gravity.

At 8:10 a.m. EDT (1210 GMT), the crew members were scheduled to speak to the media including ABC News and Comedy Central's "The Colbert Report" with comedian Stephen Colbert.

NASA currently plans to retire Atlantis after this flight, but will ready the spacecraft to serve as a rescue ship as a safety precaution for the agency's final space shuttle mission slated to fly in late November. NASA and some lawmakers have been lobbying to take that rescue mission and turn it into a full-fledged extra shuttle flight for Atlantis, but the space agency has not yet received approval to add the mission to its schedule.

After Atlantis lands, only two more shuttle flights remain, on shuttles Discovery and Endeavour, before the orbiter fleet is retired. President Obama's proposal for NASA's future post-shuttle is for new technology development and launch vehicles aimed at sending astronauts to an asteroid or Mars.

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SPACE.com is providing complete coverage of Atlantis' STS-132 mission to the International Space Station with Senior Writer Clara Moskowitz and Managing Editor Tariq Malik based in New York. Click here for shuttle mission updates and a link to NASA TV.

IN PICTURES: NASA's Space Shuttle

Editor's note: An earlier version of this story carried an incorrect byline.