Astronauts scan space shuttle for damage

CAPE CANAVERAL, Fla, Dec 20 (Reuters) The shuttle Discovery astronauts glided sensors over their ship's wings and nose today, scouting for any heat shield problems before Friday's scheduled landing in Florida.

The survey was intended to find any damage from tiny meteoroids or space debris that may have occurred since the shuttle reached orbit on December 9. The astronauts inspected their ship once already to see if it made it through the launch without problems.

Both inspections stem from safety upgrades implemented after the 2003 Columbia disaster, which was triggered by a piece of foam insulation that fell off the shuttle's fuel tank during launch and hit the ship's wing.

Damage from the impact was so severe the shuttle broke apart as it flew through the atmosphere for landing 16 days later, killing all seven crew members.

Though Discovery showed no signs of damage from launch, NASA decided the final inspection was more important than preserving the standard two-day supply of cryogenic chemicals, which are used to make electricity, for any weather-related or technical problems that might postpone landing.

Discovery's mission had been slated to last 12 days, which would have left enough supplies for the two-day reserve, but was extended a day to retract a jammed solar wing panel on the International Space Station.

Discovery departed the space station yesterday after rewiring the orbiting outpost and adding a truss segment to its backbone.

With just one day's supply of liquid oxygen and liquid hydrogen in the tanks, Discovery is poised to return to Earth on Friday. NASA mobilised all three shuttle landing sites, including its rarely used New Mexico landing strip, to improve the chances of a homecoming on Friday.

Meteorologists were predicting possible rain and clouds at the prime landing site in Florida and potentially high winds at the backup landing site in California. The White Sands Space Harbor in New Mexico, however, was expected to be clear.

NASA has only landed a shuttle in New Mexico once, in March 1982 when Columbia returned from its third spaceflight. The shuttle, which was the only one in the fleet at that time, was damaged by sand.

The Discovery astronauts will have two opportunities to land at the Kennedy Space Centre in Florida on Friday, at 3:56 pm (local time) and 5:32 pm. The first landing opportunity in either California or New Mexico would occur at 5:27 pm.

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 dollars space station.

REUTERS PKS RN0145