The International Space Station crew wrapped up its week with post-spacewalk tasks and began to turn their focus toward the arrival of a Progress supply vehicle and preparations for Discovery’s upcoming shuttle mission, STS-121.

Commander Pavel Vinogradov and Flight Engineer Jeff Williams had a busy weekend with closeout tasks and station configurations after the spacewalk last week. They finished the cleanup and stowage of the Orlan spacesuits and related tools.

The crewmembers enjoyed light duty days on Monday and Tuesday to rest after the extended spacewalk and its follow up activities, but resumed a normal work and sleep schedule Wednesday. Another off-duty day for the crew is scheduled Monday.

The crew attempted to reactivate the Russian Elektron oxygen-generating system this week following the replacement of its external hydrogen vent valve during the June 1 spacewalk. After several attempts, the Elektron began operating but failed about seven hours later. Vinogradov checked the vent lines associated with the refurbishment effort during the spacewalk and they appeared to be clear and operating normally.

But another attempt to restart Elektron earlier today proved unsuccessful, leading Russian specialists to believe that the problem is due to a failed power unit. A spare was located by Vinogradov and will be installed on Sunday for another attempt to bring the system back on line. The crew has at least a week of oxygen available in the cabin atmosphere before it would need to use supplies out of the Progress 21 cargo ship tanks. The Elektron problem has had no impact on station operations and ample alternate supplies of oxygen are available.

This afternoon, the ISS Progress 21 thrusters were used to reboost the station by a little less than one mile, placing the complex at the correct altitude for the launch and docking of the new ISS Progress 22 cargo vehicle. Progress 22 is scheduled to launch June 24 from the Baikonur Cosmodrome in Kazakhstan, and will dock to the station on June 26 at the Pirs Docking Compartment port.

That docking port currently houses the older Progress 20 resupply ship, which will be jettisoned on June 19 to make way for the new cargo vehicle.

Other work this week included some final spacewalk tool stowage tasks and the reconfiguration of the station’s systems, including the communications system in the Russian Zvezda Service Module and the Pirs Docking Compartment airlock.

The crew conducted a successful communications test with the Dryden Flight Research Center and White Sands Test Facility ground sites and performed routine emergency fire drill training. They also inspected portable breathing apparatus and fire extinguishers.

Williams participated in two amateur radio sessions, the first with the Salt Brook Elementary School in New Providence, N.J., and a second with the Scarlett Middle School, a 2004 NASA Explorer School in Ann Arbor, Mich. Both crewmembers participated in an in-flight interview with the website team associated with the State Department's Bureau of Educational and Cultural Affairs.

Williams who serves as the station’s science officer, ran a session of two colloid experiments – InSpace (Investigating the Structure of Paramagnetic Aggregates from Colloidal Emulsions) and BCAT (Binary Colloidal Alloy Test). Vinogradov worked with two Russian life science experiments – URAGAN, which is a ground and space based system for predicting natural and manmade disasters, and DIATOMEA, an ocean observations program.

FMI: www.nasa.gov/station