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Discovery to Deliver Heart of Japanese Lab to Space Station

By Cheryl Pellerin

When Discovery launches on May 31, the STS-124 mission to the International Space Station will carry the centerpiece of Japan's science laboratory complex and reach a milestone in NASA's restructuring of its space shuttle program after the February 2003 loss of Columbia in the skies above Texas.

The accident - caused by a piece of heat-insulating foam that came off the shuttle's external fuel tank and caused damage that resulted in the shuttle exploding on re-entry - prompted a series of changes to the shuttle program and the spacecraft, including the external tank.

"This will be the first mission that takes all the design modifications we did to the external tank and puts them in line in the processing of the tank as it goes through the normal assembly process," John Shannon, space shuttle program manager, said during a May 1 NASA briefing.

Before STS-124, he added, "all the modifications we did to the external tank were retrofitted onto tanks that had been built before Columbia." STS-124 will be the 10th shuttle flight since the Columbia accident; 10 flights remain until the shuttle is retired in the summer of 2010.

REPAIRING HUBBLE

The new processing schedule for the external tank will add four to five weeks to NASA's launch manifest, Shannon said, slipping the Hubble Space Telescope STS-125 repair mission, previously scheduled for August 28, to late September or early October.

"We probably wouldn't notice [the schedule slip]," he said, "except that Hubble has this unique launch-on-need requirement so we have to process and have two vehicles ready to go."

During the 11-day flight on Atlantis, NASA also will support a potential rescue flight for the mission's seven astronauts. If such a flight becomes necessary, Endeavour will lift off from launch pad 39-B at Kennedy Space Center. (See "Shuttle Returns After Delivering Canadian, Japanese Equipment ( http://www.america.gov/st/space-english/2008/March/20080327110632lcnirellep0.7743952.html ).")

During the mission's five spacewalks, astronauts will install two powerful new science instruments, a new set of the gyroscopes that help stabilize the telescope, and batteries and thermal blankets to extend Hubble's operational life until at least 2013.

"I think it's a small price to pay - four to five weeks - for all the improvements that we're getting on this tank," Shannon said. "Everything we thought of immediately post-Columbia that would be a good modification has been implemented on the tank. It's a much, much better tank than we were flying pre-Columbia but it's a more laborious process."

JAPAN'S "HOPE"

Navy commander Mark Kelly will command the STS-124 mission to deliver the pressurized module and the robotic arm of the Japanese experiment module, called Kibo (hope), to the space station. Navy commander Kenneth Ham will serve as pilot. Mission specialists include NASA astronauts Karen Nyberg, Ronald Garan and Michael Fossum; and Japan Aerospace Exploration Agency (JAXA) astronaut Akihiko Hoshide.

Gregory Chamitoff also will fly to the station as an STS-124 mission specialist to take Garrett Reisman's place as an Expedition 17 flight engineer. Reisman will return to Earth on Discovery.

STS-124 is the second of three flights that will ferry components to complete the Kibo laboratory. The mission will include two spacewalks to install the new lab and its remote manipulator system. The lab's logistics module, installed in a temporary location during STS-123 in March, will be attached to the new lab.

"The major assembly task of this mission is to install the largest and heaviest module that we've attached to the International Space Station," Matt Abbott, STS-124 lead space shuttle flight director, said.

"To fit Kibo into the payload bay, we needed to leave the orbiter boom sensor system onboard the station back on the STS-123 mission," he added, "so another major objective is to retrieve that boom so we can use it for inspections later on in the mission and after undocking."

This means inspections of Discovery's heat shield will occur later than usual in the mission. Normally the boom sensor system is attached to the shuttle robotic arm on the second day of a mission to make sure the shuttle was not damaged during launch.

Because the boom is stowed on the station, Discovery's crew will use only cameras at the end of the shuttle's robotic arm to conduct an inspection before the shuttle docks to the station. That inspection will be limited because the camera on the arm's elbow joint, which helps the astronauts steer the arm, has to be strapped down to ensure it does not touch the Japanese module during launch.

Discovery will get a thorough inspection after it undocks. An extra day has been added to the STS-124 schedule after undocking to give ground teams enough time to review the data before landing. An additional day is available if needed.

More information about STS-124 ( http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts124/index.html ) and the Hubble repair mission ( http://www.nasa.gov/mission_pages/hubble/servicing/index.html ) are available at the NASA Web site.

Source: U.S. Department of State