Work with the Elektron unit, a device that recycles waste water into oxygen, was one of several maintenance activities completed by Commander Gennady Padalka and NASA Science Officer Mike Fincke this week.
With guidance from Russian ground controllers, Padalka had replaced the Elekron's liquids unit with one he had refurbished last week using spare components. The Elektron is operating without a gas analyzer that was removed during troubleshooting. The absence of the gas analyzer does not affect the Elekron's ability to generate oxygen, although it may mean the crew will be required to more closely monitor the unit's operations. Ground controllers requested the Elektron be turned off before the crew goes to sleep tonight to allow data gathered during its operations to be evaluated.
The crew flushed and cleaned several of the Elektron's lines earlier in the week, as well as cleaning a mounting plate and removing the gas analyzer.
While the Elektron was off, the Station atmosphere was repressurized Wednesday using oxygen from the Progress supply craft docked to the complex. The Station has a supply of oxygen available in its own tanks, the Progress tanks, and oxygen-generating candles that could be used for many months if it were needed.
Meanwhile, Fincke replaced a flex hose that is used to vent an area between panes of the window in the U.S. Destiny Lab. After depressurizing the window's inner panes, he replaced the hose and installed a protective cover. The previous hose had been damaged and allowed air to leak into the area.
The crew has begun some preparations for their trip home next month. This week, they tested the UHF and VHF communication systems of the Soyuz spacecraft that will carry them back to Earth. The communication checks were done with NASA ground stations at the White Sands Test Facility, the Dryden Flight Research Center and with the Wallops Flight Facility, allowing NASA sites to be used to supplement primary Russian ground communications sites. Fincke also used a camcorder to survey all external U.S. hardware visible from the Station windows. The video has been downlinked to the ground for engineers to assess the hardware's condition. Science activities for the crew included work with the Advanced Diagnostic Ultrasound in Microgravity experiment. Assisted by experts on the ground, they conducted body scans with the equipment to practice the procedures. They also continued providing information for the Interactions investigation, a computer-based survey that helps investigators study the interpersonal relations between crewmembers and ground control teams during long spaceflights.