BEIJING, June 11 (Xinhuanet) -- Two space shuttle Atlantis astronauts prepared for a seven-hour spacewalk Monday to install a 45-foot(14-meter) 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.

    Crewmembers Jim Reilly and Danny Olivas were preparing for low pressure during their spacewalk by sleeping overnight in an airlock with reduced air pressure.

    Atlantis docked with the station on Sunday 220 miles (354 km) above the Earth and handed the 367 million U.S. dollar 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.

    Atlantis' crew is scheduled to conduct two more spacewalks during its weeklong 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.

    (Agencies)