Foale did a leak check early this week of ventilation valves that are part of the hatchway between the Station's Unity connecting module and the U.S. Quest Airlock. The valves had been disassembled and reassembled earlier this year during troubleshooting by previous Station crews. For the check, the hatch between Quest and the rest of the Station was shut and the air pressure inside the airlock decreased by about five pounds per square inch. The hatch remained shut overnight so any leakage through the valves could be measured. No leakage was detected.
While Foale worked on the leak check, Kaleri began work to replace a faulty heat exchanger in the Zvezda living quarters module's air conditioning system. After removing the old unit, Kaleri had trouble aligning connections on the new exchanger and securing it. Russian flight controllers are evaluating the problem and may continue the work next week. The primary air conditioning system is operating well, and the replacement is for a backup system.
Russian flight controllers also have been monitoring operation of the Elektron unit in Zvezda, a system that recycles wastewater aboard the Station by converting it into oxygen for the Station atmosphere. The Elektron has been operating only intermittently, shutting down when air gets into pumps that help separate liquid and gas. The problem is believed to be one that is sometimes experienced as membranes in that unit age. A replacement is onboard, but flight controllers plan to continue operations as they are for as long as possible before using the new equipment.
Oxygen also is being provided to the cabin air from tanks aboard the Progress cargo craft that to the complex. The oxygen in those tanks must be used in the next few weeks to prepare for the undocking of that supply craft in January. With the Progress oxygen being used, continuous use of the Elektron is not necessary.
Foale and Kaleri took time out on Wednesday to mark the 100th anniversary of powered flight. They spoke with schoolchildren in North Carolina and Ohio, displaying a model of the Wright Flyer, flown by Wilbur and Orville Wright in 1903. On Friday, the crew sent down Christmas greetings and displayed some of the presents from friends and families. The crew shared their plans for the holiday, showing off decorations, which include Christmas trees and stockings. Foale and Kaleri will have Christmas Day off, and will visit with their families via two-way videoconferences.
Also on Friday, Foale sent down data he has gathered as part of the Foot/Ground Reaction Forces During Space Flight experiment, a study that gathers information on the loads experienced by Station crewmembers on their lower bodies and their muscle activity as they work. The information is gathered via an instrumented pair of pants worn by Foale. Earlier in the week, Foale removed a sample from the Pore Formation and Mobility Investigation experiment that had been in processing when a circuit breaker tripped, stopping the investigation. Troubleshooting of the experiment is planned next week.