NASA Mulls Its Shuttle Landing Options

NASA's ability to deal with adversity in its space operations is legendary -- STS-116 has been no exception. Despite a balky solar panel and tools lost in space, the shuttle and ISS crews have managed to execute all STS-116 mission objectives except one so far, meeting launch and landing schedules.

NASA slipped Thursday's originally scheduled landing to accommodate an additional spacewalk to fully retract that balky solar panel. Now, it looks as though Mother Nature will have another say in NASA's schedule as the forecast at Kennedy Space Center calls for low clouds and rain showers for Friday's rescheduled landing.

As if that weren't bad enough, NASA's backup landing site of Edwards Air Force Base in California is calling for crosswinds of 20 mph -- just 3 mph in excess of the agency's 17 mph safety limit.

The agency's tertiary landing site at White Sands, NM might prove to be the only option left. Although good weather is forecast there, it's the poorest choice logistically -- NASA would have to reposition a tremendous amount of equipment to support the orbiter's return to Florida.

NASA's chief of its flight directors’ office Phil Engelauf told the Associated Press, "More than likely, we will evaluate the conditions on a case-by-case basis on Friday and pick the lesser of evils."

Discovery's crew will continue with landing preparations today including tests of the shuttle's flight control system, stowing loose items and deploying a small satellite. Ground controllers are expected to give a thumbs-up after studying pictures of the shuttle's heat shielding the crew transmitted earthward on Wednesday.

There is a note of urgency in NASA's landing site dilemma. In the past the agency hasn't been shy about delaying a shuttle's landing to wait for better weather at its landing site of choice. This time, NASA wants the shuttle down no later than Saturday -- that's when the fuel cells providing Discovery's primary power run dry.

A landing in New Mexico poses some concerns for the space agency, but none that would interfere with getting Discovery on the ground safely. The last time a shuttle landed at White Sands in 1982, fine sand on the runway contaminated the shuttle's exterior and damaged its brakes.

Engineers are also worried freezing weather over the weekend there might damage the shuttle's thrusters and freeze water and fuel lines.

Additionally, complicated logistics issues mean a landing at White Sands will delay the shuttle's return to Florida by a month, and flying the orbiter back there piggy-back on the agency's special-purpose 747 is expensive.

It's unclear how a delay in returning Discovery to Florida might interfere with NASA's launch schedule for 2007. Three shuttle launches have already been pushed back for next year.

NASA says it has seven chances for a landing at any of its three landing sites Friday and Saturday.

FMI: www.nasa.gov