NASA Prepares for Shuttle Landing Contingencies
While the upcoming launch of the space shuttle Discovery will mark the return to flight of NASA’s space shuttle fleet, it is only the beginning of the great care being taken to assure a successful mission throughout, particularly the landing, wherever it might take place.
To ensure a safe return of Discovery’s astronaut crew, shuttle officials at NASA’s Dryden Flight Research Center and Edwards Air Force Base, Calif., have conducted training drills in the off-chance the orbiter makes a West Coast landing instead of touching down at Kennedy Space Center in Florida as planned.
“We try to have one major practice about every six months,” said Joe D’Agostino, head of Dryden’s shuttle support office, in a telephone interview. “That includes getting the whole NASA, Air Force, Army and Navy team together to practice a contingency operation.”
While Kennedy Space Center is NASA’s preferred landing site for Discovery — and all shuttle missions since 1990 — the space agency turns to Edwards Air Force Base and White Sands, N.M., when weather conditions make a Cape Canaveral landing impossible. Thunderstorms, wind speeds and cloud ceilings will all play a role in whether shuttle flight controllers opt for a contingency landing, shuttle officials said.
“Basically, what we’re looking for is no thunderstorms and, obviously, no rain,” said LeRoy Cain, ascent/descent flight director for Discovery’s mission, which NASA named STS-114. “We’re not going to risk flying through rain if it is within 48 kilometers (30 miles) of [Kennedy Space Center].”
Discovery’s STS-114 mission is NASA’s first bid at resuming space shuttle flights since the 2003 Columbia accident that led to the loss of one orbiter and the deaths of all seven STS-107 astronauts. The Columbia orbiter broke apart during re-entry Feb. 1, 2003, about two weeks after sustaining wing damage during launch.
Shuttle engineers have spent the last two years revamping Discovery and its sister ship, Atlantis, to increase flight safety. They have also redesigned portions of each orbiter’s external tank to reduce the shedding of potentially damaging debris. The Columbia Accident Investigation Board concluded that the wing was breached shortly after launch when it was struck by foam debris that fell off part of the external tank system.
Discovery is set to launch toward the international space station no earlier than July 13, and return about 12 days after liftoff.
While NASA has focused much of its attention on minimizing, if not eliminating, the same type of launch debris that doomed Columbia, there are new concerns for landings, NASA officials said.
“If there’s the possibility of debris coming off an orbiter, we’ll want less exposure to the public and that might favor a scenario at White Sands rather than Dryden or [Kennedy Space Center] ,” D’Agostino said. “Our first and foremost requirement [in addition to astronauts] is the safety of the general public.”
Search teams collected 37,648 kilograms of the debris that rained down from the Columbia orbiter, primarily over Texas, as it crumbled during re-entry. “We were very fortunate during the tragedy of STS-107 that we did not injure anyone on the ground,” D’Agostino said.
If Discovery’s STS-114 mission goes as planned, it should land at Kennedy Space Center during daylight, though NASA officials said it is not a flight constraint.
“We have a daytime launch constraint, which puts us in a daytime landing,” Cain said.
Shuttle officials set the daylight launch constraint for Discovery’s STS-114 flight, and NASA’s follow-up STS-121 mission aboard Atlantis, in order to allow good observation conditions for ground and air-based cameras.
Cain, who also oversaw Columbia’s re-entry, said Discovery’s landing conditions must include at least 8 kilometers of range visibility, with cross winds not exceeding 15 knots among other constraints. The surface wind criteria, he added, protect the orbiter from putting too much pressure on its landing gear struts.
The last shuttle to land at Edwards was Endeavour during the STS-111 mission in June 2002, but Dryden and military officials are prepared to receive an orbiter.
“It’s really weather-driven,” D’Agostino said, adding his crews are ready when landings near. “We went four and a half years without a landing, and then had four in a row, so you never can tell.”
Originally tapped as the prime shuttle landing site, Edwards Air Force Base is fully equipped with the necessary hardware and support crews to not only safeguard an orbiter after the wheels stop, but also turn it around for shipment back to Kennedy Space Center atop a modified 747 aircraft.
“That will be the first site I look at, and primarily it’s because there we have a little bit better understanding of the weather,” Cain said. “But more importantly, there is more support in the post-landing … [Edwards] is a fully augmented landing site.”