Station Moved To Avoid Yet Another Chunk Of Space Debris

Problems with a vital water purification system onboard the International Space Station may be more than skin deep, after the system stubbornly refused to work during testing Sunday.

NASA reports Expedition 18 Commander Mike Fincke spent much of the day working with the Urine Processing Assembly, after installation of a new distillation assembly delivered by Discovery's STS-119 crew. The new unit was ferried up to the station after astronauts encountered problems with the system during a previous shuttle flight to the station, as ANN reported.

Proper operation of the UPA is necessary for the station to support a full six-person crew complement... due to be onboard the ISS in May.

First results were encouraging. Initially the system showed a lower than expected flow rate when attempts were made to fill the reservoir tank, but after a tank swap, the tank was filled. Reuters reports a second "dry spin" of the unit also succeeded... but when Fincke started a "wet spin" test, with actual urine, things ground to a halt.

"Once you closed valve 3 it didn't seem to flow," Fincke radioed to ground controllers. "I have no idea why that could be, so good luck with the trouble-shooting and we're standing by to answer any questions or be of any use."

Also of note Sunday, NASA repositioned the station-shuttle complex in order to avoid a piece of debris from a nine-year-old Chinese rocket, that might have come a bit too close to the ISS during Monday's planned third and final spacewalk of the STS-119 mission.

Somewhat oddly, thrusters onboard the station were used to propel the ISS ever-so-slightly closer to Earth, where the atmosphere will generate enough friction to slow the station enough to allow the debris to speed past uneventfully.

"That'll slow the whole stack down by just a bit," said mission commentator Kelly Humphries.

Mission Specialists Joe Acaba and Ricky Arnold prepared tools and equipment for their Monday morning spacewalk, before moving to the Quest airlock to "campout" in the Quest airlock to condition their bodies ahead of the spacewalk set to begin at 10:43 am EDT.

They plan to relocate an equipment cart from one side of the station's Mobile Transporter to the other; attempt to complete a deploy of a cargo carrier that exhibited a balky handle during the second spacewalk Saturday. They also will deploy a payload attach system and complete work to swap electrical relays to the station's gyroscopes.

One last task will be to lubricate the latching end effector on the station’s robotic arm -- a routine maintenance task to prevent stickiness during latching procedures.

FMI: www.nasa.gov/shuttle