Sticky Valve May Extend Shuttle Mission

Flight controllers today struggled to open a stuck valve in a cooling loop at the International Space Station. For now, the space station is being cooled properly, but the valve needs to be opened or the entire nitrogen unit replaced, otherwise half of the station’s electronics may have to be turned off. Rod Rice reports on NASA’s options.

The effort to open the valve from the ground has been to no avail.   Ron Spenser, the lead space station flight director says while work continues on the ground, a spacewalk, or EVA might be necessary to swap the nitrogen tank for one of the two extra ones at the space station. That would be done by either extending the shuttle mission for a 4th spacewalk or having it done after the shuttle leaves by members of the space station crew.

Spenser says there are several reasons to go with the shuttle crew.

“One is that this task, although it was not planned for this flight, it has a lot of similarities associated with the ammonia tank replacement and so the EVA crew on this mission are familiar with the fluid connections, the electrical connections.”

And he says with manhandling a tank around the outside of the space station.

The reasons to wait and let the space station crew do the EVA are that there is no contingency plan ready to go to swap out the nitrogen tank and so the more time to plan the better.  And Spenser says the 13 day shuttle mission has already had three EVAs.

“And in this case it would be the same EVA crew going out to do the fourth EVA and so we are concerned a little bit about crew fatigue.”

Spenser says they’d like to make a decision on what to do by tomorrow night.