HOUSTON, Nov 7 (Reuters) Astronauts aboard space shuttle Discovery closed their ship's payload bay doors today in preparation for landing in Florida following a successful 15-day mission to prepare the International Space Station for new laboratories.
The shuttle and its crew of seven was scheduled to land at Kennedy Space Center in Florida at 1:01 p.m. EST (1801 GMT), NASA said. Weather at the Florida spaceport was cool, sunny and clear and expected to be perfect for landing.
The US space agency said Discovery would fly across the United States as it returned -- the first time a shuttle takes this path since Columbia broke apart during its descent in February 2003.
Thousands of Columbia pieces showered eastern Texas and Louisiana, prompting NASA to favor a more southerly return route that crosses mostly water as it heads to the spaceport on Florida's east coast.
But NASA officials chose the cross-country path to avoid a more dangerous night landing for shuttle commander Pam Melroy.
Columbia broke apart and its seven astronauts were killed because launch debris caused damage to the shuttle's heat shield that went undetected.
NASA, which now uses a laser-tipped robot arm to perform in-flight heat shield inspections, said no damage had been found on Discovery, clearing the ship for landing.
''I've got no worries about my thermal protection system,'' entry flight director Bryan Lunney told reporters at Johnson Space Center in Houston. ''The vehicle is in great shape.'' He also said weather forecasts for the landing strip at Kennedy were good.
NASA is scheduled to deliver Europe's Columbus laboratory to the space station on a December shuttle flight and hopes to start bringing up the Japanese Kibo lab in February.
Plans are to complete the 100 billion dollars international outpost before the aging shuttle fleet is retired in 2010.
Discovery brought the Italian-built Harmony module to the space station, adding the first new living space to the outpost in six years.
IMPROVISED REPAIR But NASA's expansion plans were almost derailed by a solar power panel that tore in two places as it was being unfurled last week.
Astronaut Scott Parazynski made an unprecedented spacewalk to the farthest reaches of the station to perform an improvised repair to the 110-foot-long panel.
While working at the tip of the station's robot arm, extended by a boom borrowed from the shuttle, he had to take care to avoid contact with the electricity-producing solar cells.
The successful fix prevented a power shortage and station stability problems that would have threatened future station construction, NASA said.
Still awaiting repair is a massive circular joint that rotates solar panels on the other side of the station to keep them pointed at the sun for maximum power production.
The 10-foot joint, installed on the station in June, has been dragging in recent weeks and was found by spacewalker Dan Tani to have metal shavings inside -- an indication that metal is grinding.
NASA locked the wheel in place to minimize damage while it tries to determine the problem and how it can be fixed.
Tani is remaining at the station, trading places with Clay Anderson, who is returning after a five-month stay at the outpost.
REUTERS NC SK RAI2130