Discovery space shuttle crew tests systems

Los Angeles, Dec 21: NASA kept a close eye on worrisome weather forecasts today at its primary space shuttle landing sites, where low clouds and high winds threatened to interfere with Discovery's scheduled landing.

The shuttle's crew was to spend the day testing its steering and braking systems and securing equipment inside the cabin before returning to Earth tomorrow.

As part of routine tests, NASA and the shuttle crew will activate hydraulic power units that control Discovery during launch and landing; test its rudder, brakes and flaps; and fire steering jets used during descent.

The astronauts also will stow belongings and equipment not needed for landing and check communications with each of the three landing sites, in Florida, California and New Mexico.

The crew also is scheduled to deploy a third satellite from the shuttle's payload bay, and give a last in-flight round of media interviews.

Discovery's dwindling supply of liquid oxygen and liquid hydrogen, which power its electrical system, means the shuttle must land by Saturday.

Forecasts for tomorrow are for low clouds and thunderstorms at Kennedy Space Center in Florida, the shuttle's primary landing site, and for high winds at the back-up landing site at Edwards Air Force Base in California.

USED NEW MEXICO ONCE

Although the rarely used landing site at White Sands Space Harbor in New Mexico expects clear weather, NASA managers yesterday said they prefer not to land there.

NASA has only landed a shuttle in New Mexico once, in March 1982 when Columbia returned from its third spaceflight. The shuttle was damaged by sand.

Mission controllers are expected to finish analyzing data from yesterday's heat shield inspection and clear Discovery for landing tomorrow.

NASA extended Discovery's stay at the International Space Station by a day to retract a jammed solar panel. As a result, the shuttle spent an extra day in space, drawing on its back-up fuel supplies, to allow the crew to inspect its heat shield before the fiery re-entry into Earth's atmosphere.

The inspections stem from safety upgrades implemented after the 2003 Columbia disaster, in which the shuttle broke apart from heat shield damage and killed all seven astronauts aboard. The disaster halted construction on the space station until this year.

Discovery left the space station on Tuesday after its crew rewired the orbiting outpost and added a truss segment to its backbone. The shuttle also dropped off supplies and new station crewmember Sunita Williams, and picked up returning German astronaut Thomas Reiter during its 8-day stay.

The Discovery astronauts will have two chances to land at the Kennedy Space Center in Florida tomorrow, at 0226 hrs IST and 0402 hrs IST. The first landing opportunity in either California or New Mexico would be at 0357 hrs IST.

Discovery's flight is the fourth since the Columbia accident.

NASA plans to fly at least 13 more missions to complete construction of the half-built, 100 billion dollar space station before the shuttle fleet is retired in 2010.

REUTERS