As Discovery Heads Home, NASA Prepares for Landing

HOUSTON - Flight controllers are watching the weather for Discovery's return to Earth Monday and are planning alternate landing sites should rain storms in Florida prevent the early-morning touchdown, mission managers said Saturday.

The shuttle undocked from the International Space Station (ISS) earlier today and flew around the orbital platform before heading back to Earth.

"The undocking and fly-around both went by the book," said Paul Hill, lead shuttle flight director for the orbiter's STS-114 mission. "We couldn't be happier with the operational success of STS-114."

Discovery's only landing target Monday is NASA's Kennedy Space Center (KSC) in Cape Canaveral, Florida, where it launched spaceward on July 26. While the orbiter is slated to land at 4:46 a.m. EDT (0746 GMT) on Aug. 8, it could also land 5:21 a.m. EDT (0921 GMT) if weather prevents the initial attempt.

Both KSC and a contingency runway at Edwards Air Force Base in Southern California will be on call Tuesday if needed, shuttle officials said, adding that a third airstrip in White Sands, New Mexico is also a landing option.

Current weather predictions at KSC call for light and variable winds, a few scattered clouds and a slight chance of rain during the predawn hours of Discovery's landing opportunities, they added.

"That's about as good a forecast as you're going to get in Florida, but I have high hopes," said Wayne Hale, NASA's deputy shuttle program manager, during a press briefing here at Johnson Space Center. "You don't commit until it's time to de-orbit."

By a chance of orbital mechanics, most of Discovery's Monday landing approach will be over water - though it will pass over parts of Central America and Cuba before reaching south Florida and homing in on the at the Shuttle Landing Facility runaway at KSC. That ground track poses little risk to the populations the shuttle flies over, a new consideration for NASA since the Columbia orbiter broke apart over Texas in 2003, scattering debris across the region, shuttle officials said.

"These ground tracks are low risks in terms of public overflight hazards," Hale said. "This is a new topic for us, [and] it's not a concern for our primary landing site at the Kennedy Space Center."

Should Discovery and its STS-114 crew, commanded by veteran astronaut Eileen Collins, be forced to land at Edwards Air Force Base, flight controllers have tweaked two trajectories to shift them away from passing over major population areas in the Los Angeles Basin, Hale said.

Limiting flight over populated areas is largely tied to whether Discovery is suffering from any hazard concerns. This is not the case for the STS-114 flight, shuttle officials said, citing data from sensors inside the orbiter's wing leading edges that confirm no impacts from micrometeorites at all thus far in the 13-day mission.

"We thought the batteries were going to run down after 36 hours," Hale said of the sensors, which were primarily designed to monitor wing impacts and temperatures during launch. "This vehicle is in extremely clean shape."

Discovery's STS-114 flight is NASA's first shuttle mission since the 2003 Columbia accident, which claimed the lives of seven astronauts and destroyed their spacecraft. Investigators later found that a chunk of foam insulation fell from Columbia's external tank and pierced the shuttle's heat shield during launch, critically wounding the orbiter. The resulting damaged allowed hot gases to enter the orbiter's wing during reentry and destroy the vehicle on Feb. 1, 2003.

Hale said there are about 47 in-flight anomalies that shuttle engineers will have to address from the STS-114 flight before they launch the space shuttle Atlantis on NASA's second return-to-flight mission. The Sept. 22 launch target for Atlantis' STS-121 spaceflight discussed Friday by NASA officials remains tenuous due to the work required, he added.

Discovery must be turned around and prepared to serve as a rescue shuttle for Atlantis' STS-121 mission, and there work still remains to prepare Atlantis itself for launch, Hale said. There is also the challenge of addressing the foam debris shedding seen during Discovery's launch, which shuttle officials have pledged to understand and fix before Atlantis or any other orbiter flies.

"I would not call that a serious launch date at this point," Hale said of Atlantis' Sept. 22 target. "It's just a date for people to start thinking about, is there something we can do by then or not."

Meanwhile, all eyes will be on Discovery and its STS-114 crew during Monday's planned reentry, shuttle officials said.

"I'm looking forward to watching the crew walk off the orbiter in Florida," Hill said.

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