A U.S. astronaut and Russian cosmonaut have taken a spacewalk outside the international space station to work on an aging air conditioner and install communications antennas.
Crewmen Michael Fincke and Gennady Padalka spent nearly six hours outside the station repairing a pump on a Russian cooling system and installing three antennas on the Russian module. Ground controllers will communicate through the antennas to remotely guide a new, unpiloted European cargo vehicle when it arrives on its maiden visit late next year.
The new cargo carrier will have two-and-a-half times the storage space of the Russian rockets that currently supply the outpost. This would ease supply shortages of the type that have affected the station in the aftermath of the shuttle Columbia disaster last year. The large capacity U.S. space shuttles have been grounded for safety modifications, severely limiting the amount of cargo the outpost gets.
Unlike the last spacewalk, the station did not mysteriously tilt almost straight up this time due to some unknown force. But expecting that it might, ground controllers had turned off several pieces of equipment inside the station to conserve power during the outing, because if another tilt turned the solar energy panels away from the sun, there would have been extra demand on batteries.
One theory is that the unexplained force pushing the station upward last time might have been air escaping from an open hatch door or from the spacesuits. To test that, engineers asked the two crewmen to stay motionless for 30 minutes. U.S. flight director Matt Abbott says technicians will continue to troubleshoot the issue during future spacewalks.
"We're still continuing to try to find better ways to characterize that and to do some tests to see if we can understand where it's coming from," said Mr. Abbott. "Because we don't know where it's coming from, we haven't really been able to design a whole lot of test cases yet that we've been able to work into the timeline. Of course, we've got to work with our Russian counterparts to do that."
Friday's spacewalk was the fourth and final one for crewmen Padalka and Fincke on their six month tour of space station duty. They will be replaced in one month. All of their outings have taken place without a third astronaut to monitor their activities and the station from inside, as was once standard procedure. The third crew position has been temporarily eliminated because of the limit on supplies during the U.S. shuttle stand down.
Because of these cargo limits, engineers and the crewmen have had to improvise repairs in orbit instead of exchanging equipment on supply flights. For example, spacewalk director Paul Boehm says astronaut Finke recently fixed a faulty pump that was blocking coolant flow in one U.S. spacesuit.
"We've also done things where we've created new pieces of hardware on board to do these operations, because these suits were not designed to be maintained in orbit, so have actually had to, on the ground, take a look at pieces and parts and see what we could fit together to make the tools to get things done," he added.
Space station officials say such improvisation will be necessary during long space exploration flights that NASA is planning in later years.