Endeavour Mission Doubles Space Station Crew Capacity, Improves Solar Array Mechanism, May Provide Water Supply Solution After 2010

Fourth And Final Spacewalk Performed Today

Space Shuttle Endeavour will wrap up the STS-126 Mission to the International Space Station when the shuttle orbiter vehicle lands Saturday at Kennedy Space Station.

Meanwhile, its crew is working hard to finish myriad tasks in a busy mission dealing with multiple problems.

The crew is racing against time to try to get a balky new system, the Urine Processor Assembly (UPA), working before Endeavour departs from the space station.

The system, which is supposed to recycle astronauts’ urine and sweat into drinkable water, is critical to doubling the space station crew capacity next year from three to six.

Until now, space station crew members have been drinking tons of water hauled from Earth, a major undertaking. But the brawny U.S. space shuttles must cease flying in 2010, President Bush has ordered. And the next-generation U.S. spaceship, Orion-Ares, will have a much smaller payload capacity and won’t begin manned space flights until 2015.

After being installed, the multi-million-dollar UPA recycling system repeatedly has shut down.

Space station capsule communicator Terry Virts notified station Commander Mike Fincke and Flight Engineer Sandra Magnus that engineers have determined the UPA suffers a mechanical problem with the centrifuge in the distillation assembly of the UPA.

Astronauts are attempting to make on-orbit fixes, rushing to get it working so they can bring back treated-water samples for laboratory analysis on Earth.

Lab technicians would have to determine whether the water was safe to drink, before letting space station crew members drink it.

As well, the STS-126 Mission includes four challenging spacewalks, including one today, to solve a long-standing problem hampering the space station from gaining maximum electrical power.

Giant solar arrays generate electricity, with huge Solar Array Rotary Joints (SARJs) keeping the arrays pointed toward the sun for maximum generating capability. But one SARJ, on the port side, became balky, with filings and debris on it.

It had to be cleaned and lubricated, and crew members accomplished that. One astronaut, Heidimarie Stefanyshyn-Piper, opened a tool bag containing a lubricant applicator, like a caulk gun, and discovered it oozed lubricant all over the inside the bag. As she attempted to deal with the errant lubricator, the tool bag drifted away into space. That forced her and fellow spacewalker Steve Bowen to share equipment. But the important point is that the job of fixing the SARJ, including replacing the problematical trundle bearing, was accomplished. And that bad bearing will be returned to Earth on Endeavour for analysis.

This isn’t the first time that tools have been lost during spacewalks. Other astronauts have had the same experience, watching a tool they need float into the darkness.

NASA hasn’t at this point announced whether engineers will begin working on some system, such as a rod with a hook, or a scissors-type extension arm, that could be used to reach out and grab tools or other items that get loose and begin drifting away in space.

The spacewalk today began at 1:45 p.m. ET, lasting 6.5 hours. Mission specialists Bowen and Shane Kimbrough performed more port SARJ servicing work. Their other tasks included installation of a video camera on the P1 truss and work on the Kibo laboratory built by Japan and brought to the space station by NASA shuttles.

If all that wasn’t enough, the STS-126 Mission also has involved physical labor, moving tons of equipment from the Leonardo European cargo capsule, built by Thales Alenia Space, that Endeavour brought to orbit. Items such as beds, toilet facilities, ovens and more are crucial to doubling the station crew capacity.