NASA set to try again for shuttle landing
Three sites under consideration after weather delays touchdown
From Thom Patterson
Programming note: CNN has live coverage of the Shuttle Discovery landing, "Daybreak," starting at 4:30 a.m. ET.
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KENNEDY SPACE CENTER, Florida (CNN) -- NASA officials vowed to land Discovery early Tuesday at one of three locations after weather conditions forced them to scrub the shuttle's scheduled return Monday morning.
The next opportunity is scheduled for Tuesday at 5:07 a.m. ET at the Florida landing site. It would be the first landing for a shuttle since the 2003 Columbia disaster.
The crew aboard Discovery was awakened at 8:39 p.m. ET Monday to prepare for the landing.
"We sure hope we get our feet on the ground," Mission Specialist Wendy Lawrence radioed down after the wake-up call.
Mission controller LeRoy Cain said NASA's weather forecast for Tuesday morning at the Florida site called for similar conditions, including possible clouds, light and variable winds, and a chance for rain within 30 miles.
Alternative sites were prepared at Edwards Air Force Base in California as a second choice and at White Sands Missile Range in New Mexico as a third choice.
"We'll land somewhere tomorrow," he said.
Officials would prefer to land at Kennedy Space Center to avoid the cost and inconvenience of flying the shuttle back to its launch site from the alternative landing strips.
NASA said Edwards is forecast to have acceptable conditions for landing Tuesday; the forecast for White Sands includes a chance of showers.
Of the 111 previous shuttle landings, 61 touched down in Florida, 49 at Edwards and one at White Sands.
"We are going to come in and make a real earnest attempt at the first two opportunities to [Kennedy]," Cain said. "If we can't make it there, we will be looking at Edwards."
Cloud cover in Florida on Monday, although within NASA's safety limits for landing, was enough to prompt mission controllers to scrub two chances for landing.
"We just can't get comfortable with the stability of the situation for this particular opportunity. So we're going to officially wave you off for 24 hours," Ken Ham at Mission Control told the shuttle.
"OK, Houston we copy that. We'll be a wave off for today," responded shuttle commander Eileen Collins.
Mike Fincke, an astronaut who spent six months in space on the international space station, told CNN that Collins wouldn't have had much time to see the runway clearly.
"Eileen Collins is an experienced test pilot, and she'd be able to land almost blindfolded. But there's no reason to take that risk," he said.
"This morning we thought there might be a cloud deck of about 500 feet, and that would have obscured the runway."
Mark Polansky, a pilot during a 2001 mission aboard the shuttle Atlantis, said the waiting is easier for orbiting crew members than it is for their families.
"It's much harder for people on the ground," Polansky said. "Loved ones don't know when their people are coming home."
Polansky and astronaut Nicholas Patrick are assigned to a shuttle mission aboard Discovery in 2006. Patrick said the orbiting astronauts have more than enough supplies.
"In between powering down today and preparing for Tuesday's landing attempt, they'll be taking care of some housekeeping and perhaps finding more time to be looking out the windows," Patrick said.
Following the decision to remain in space another day, Discovery received permission to re-open its payload bay doors and began powering down systems that had been poised to fire engines to take it out of orbit.
During the de-orbital burn before Tuesday's scheduled landing, the spacecraft's engines will ignite for about three minutes, slowing it enough to begin its fiery journey through the atmosphere.
Discovery's pilot, astronaut James Kelly, said Sunday that returning to Earth is much like riding on "a runaway train."
It's "a very exciting and exhilarating process that ends with being at home," Kelly said.
Though it launches into orbit like a rocket, the shuttle returns to Earth like an airplane. As it begins to transition from space, computer-controlled jets guide the shuttle.
Once the atmosphere thickens, Discovery's wing flaps and rudder steer it much like they would a conventional aircraft.
When the shuttle slows below the speed of sound, it triggers a sonic boom that alerts Florida residents that the spacecraft is returning home.
It was during re-entry in February 2003 that Columbia broke apart, killing its seven crew members.
Investigators later determined that super-heated gases that normally surround the orbiter as it returns to Earth entered Columbia's left wing through a hole created when insulating foam fell from the shuttle's fuel tank and struck the vehicle during launch.
The Columbia break-up left a trail of debris across Texas and Louisiana and resulted in vows from NASA that tighter safety precautions would be taken on future trips -- and that the problem of falling foam would be solved.
Under new guidelines, Discovery will follow a trajectory that takes it largely over ocean.
Mission STS-114 largely was designed to improve safety on future shuttle journeys, although the program has been suspended while NASA investigates its failure to solve the problem of foam falling from the shuttle's external liquid fuel tank during launch.
Video from the July 26 launch showed debris falling from the fuel tank, but NASA said it did not appear to have struck the orbiter.
Once in space, Discovery's crew used cameras to scrutinize the craft's exterior for possible damage that might pose a threat during re-entry.
The shuttle spent most of the mission docked to the international space station, delivering much-needed supplies and performing maintenance on the outpost.
Astronaut Steve Robinson performed an unprecedented shuttle repair mission by plucking two pieces of filler material protruding between tiles on Discovery's underside.
NASA wanted them removed to ensure they wouldn't overheat, damaging Discovery's belly during re-entry.
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