Three spacewalks before Atlantis can launch

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Three spacewalks at the International Space Station must be completed before Atlantis can launch on the next mission, now planned for a launch window between Dec. 6 and 13.

The space station crew must perform 15 days of work during the ten days between Nov. 26, when the Harmony module is scheduled to open, and Dec. 6, when Atlantis is now scheduled to launch.

"We have to go figure out what work we can get rid of," said Expedition 16 lead flight director Holly Ridings.

Discovery is poised for a 1:01 p.m. EST landing Wednesday at Kennedy Space Center. A backup landing opportunity comes at 2:36 p.m.

However, the first spacewalk at the space station begins at 5 a.m. Friday to prepare for the next mission.

Discovery delivered the Harmony module to the station, but it must be relocated and a pressurized mating adapter must be attached. Then a complicated set of electric wires, communication cables and ammonia lines must be connected to make the Harmony module ready to accept the next shuttle and two laboratory modules.

Atlantis is scheduled to carry the first of these modules up on Dec. 6. If Atlantis doesn't launch by Dec. 13, it must wait until January, due an unfavorable angle of the sun.

"Launching in December is a priority for all of us," said Pete Hasbrook, Expedition 16 increment manager. "It's not just an American mission we're going into. It's a commitment to the international partners to do what we can to make the December launch."

The schedule roughly follows this plan:

Nov. 9: Two spacewalkers disconnect cables on PMA2.

Nov. 12: PMA2 is robotically moved the Harmony module, which is robotically moved to the location were PMA2 was previously.

Nov. 20: 2nd spacewalk to connect umbilicals on Harmony module.

Nov. 24: 3rd spacewalk to finish connection of cables, wires and ammonia lines.

Nov. 25: Final activation of Harmony module.

Nov. 26: Opening of Harmony module.

After Nov. 26, astronauts at the space station must work feverishly to prepare the Harmony module to accept the Columbus module, which was built by the European Space Agency.

Another problem that remains is a damaged Solar Alpha Rotary Joint, which has been still since metal shaving were found on the joint.

NASA managers will study the shavings to determine whether they come from drive locks or trundle bearings. They are trying to find room on Atlantis for the 300 pounds of spare parts that would be needed to fix the joint.