Astronauts on space shuttle Atlantis prepared for a walk in space on Monday to add a giant new piece to the International Space Station, and NASA engineers pondered whether a bump in the ship's heat protection system needs repair.
Atlantis crewmembers Jim Reilly and Danny Olivas were to make a seven-hour spacewalk to install a 45-foot (14-metre) long, 35,678-pound (16,183-kg) aluminum structure that will become part of the station's exterior backbone and includes solar panels to generate more electricity.
Atlantis docked with the station on Sunday 220 miles (354 km) above the Earth and handed the $367 million module in its cargo bay to the station's robot arm.
Once the unit is in place, Reilly and Olivas will hook it to the station; on Tuesday the solar array will be deployed.
The panels will add a net 14 kilowatts of electricity to the international space station, which will be needed as upcoming shuttle flights add new sections.
NASA plans 12 more shuttle missions to complete the $100 billion station, a project of 16 nations, before the aging shuttle fleet is retired in 2010. Another mission is planned for maintenance on the Hubble Space Telescope.
Reilly and Olivas were preparing for low pressure during their spacewalk by sleeping overnight in an airlock with reduced air pressure.
Atlantis' crew is scheduled to perform two more spacewalks during its week-long station visit to retract an old solar array and possibly repair a thermal blanket that peeled back slightly during Friday's launch.
The blanket protrusion exposed a few inches of underlying layers of the shuttle, which could lead to damage during the heat of re-entry, deputy shuttle manager John Shannon said.
He said the size and location of the problem meant any damage would not be catastrophic, but could require repair once Atlantis returns from its scheduled 11-day mission.
"I would just like to avoid that scenario altogether and tuck that blanket back down," Shannon said.
Fixing the bump would be a simple chore that could be incorporated if time permits into the third spacewalk, scheduled for Friday. If not, it would mean a fourth spacewalk.
The shuttle Columbia disintegrated while returning to earth in 2003 because of a break in the heat shield on its wing, caused by insulating foam flying off the fuel tank at takeoff. The seven astronauts on board were killed and NASA has since approached heat shield problems with great caution.
NASA said there appeared to be no other heat shield issues on Atlantis, save for a gap filler on the shuttle belly that photographs taken from the station showed protruding about 3/4 of an inch.
(Reuters, 11/06/2007)