Expedition 9 Commander Gennady Padalka and NASA ISS Science Officer Mike Fincke took part in a variety of experiments that focus on learning how the human body responds to extended periods without gravity. The crewmembers completed the first sessions of a series of Russian biomedical experiments measuring body mass and calf volume and drawing blood to measure red blood cell mass. They also performed operations with two European Space Agency experiments looking into adaptation of the vestibular system, which provides the body's sense of balance.
Padalka and Fincke launched with plans to conduct two spacewalks, but they learned last weekend that a third had officially been added. The planned June 10 spacewalk calls for the crewmembers to replace a Remote Power Controller Module (RPCM), a type of remote controlled circuit breaker, on the Station's truss. The RPCM failed April 21, cutting power to one of the Control Moment Gyroscopes (CMGs) which provide attitude control for the Station. There are still two CMGs operating well and controlling the Station's orientation. As managers continue to evaluate the spacewalk plans, Padalka and Fincke will conduct a fit check of the U.S. spacesuits next week. This week, Fincke completed maintenance work with the spacesuit battery chargers and batteries and began a procedure to regenerate canisters which remove the carbon dioxide spacewalkers exhale from the suits. The previous Station crew, Expedition 8 Commander Mike Foale and Flight Engineer Alexander Kaleri, are at the Gagarin Cosmonaut Training Center in Star City, Russia, this week for post-flight debriefings and checks. Foale is expected to return to Houston later this month.