Heading into the homestretch of their six-and-a-half month mission aboard the International Space Station, Expedition 8 Commander Michael Foale and Flight Engineer Alexander Kaleri spent the past week conducting biomedical experiments and performing maintenance for a key Station component.
Foale and Kaleri spent two days replacing a liquids unit and a water flow system in the Russian Elektron oxygen-generation device in the Zvezda Service Module, after weeks of troubleshooting failed to coax it back into service. The Elektron produces oxygen for the Station cabin atmosphere through electrolysis, the separation of hydrogen and oxygen from water that flows through a series of pumps and valves. The hydrogen is vented overboard, leaving the oxygen for crew support.
Russian specialists spent several weeks trying to track down the cause for repeated shutdowns of the system after just a few minutes of operation. They concluded contaminate particles of potassium hydroxide electrolytes, a by-product of the electrolysis process, created air bubbles in the liquids unit, resulting in the unit’s repeated shutdown.
Since last Saturday, the crew has derived oxygen from solid-fuel oxygen generation (SFOG) canisters that are activated in Zvezda. The crew has used an average of two SFOGs daily, since air and oxygen was depleted from tanks in the Russian Progress supply vehicle, following the first shutdown of the Elektron.
Russian engineers will spend the weekend reviewing the results of the repair procedures. They plan to activate the refurbished Elektron tomorrow for a few days of checkouts and diagnosis. If the Elektron repair is successful, the SFOG canisters will no longer be needed. There is an ample supply of canisters, as well as oxygen contained in the Quest airlock tanks, to provide oxygen for the Station for several months, if needed.
Today, Foale did a leak check of the window in the Destiny laboratory. In January, a flex hose that helps to vent air from the inner panes of the window was causing minor pressure decay from the Station. Although the flex hose is operating normally, today’s check revealed a slight leak from one of the inner panes of the window.
The leak will not affect the pressure in the Station, but it will require another venting procedure in the next week or so to prevent condensation buildup.
Foale spent time this week conducting experiments with a cellular biotechnology device to test methods for improved cell culture growth and with a device designed to measure the forces imparted on the joints of the lower extremities and the feet in the absence of gravity.
The crew also worked on the Pore Formation and Mobility Investigation in the Microgravity Science Glovebox. This experiment studies how bubbles form in materials. It gives scientists an opportunity to observe bubble dynamics in a sample being processed in a way similar to industrial methods. Researchers hope to gain insights that will improve solidification processing in a microgravity environment. The generated data may also promote our understanding of processes on Earth.
Last week, scientists saw the completion of a record-breaking 31-day experiment on the Station, called PromISS-3. It’s the longest duration experiment ever conducted inside the Microgravity Science Glovebox, built by engineers and scientists at the European Space Agency (ESA) in collaboration with NASA’s Marshall Space Flight Center in Huntsville, Ala. The Glovebox, a sealed container with built-in gloves, provides an enclosed workspace for investigations conducted on the Station.
Sponsored by the ESA, PromISS-3 was an experiment to study the growth of protein crystals. Among the proteins grown were iron storage proteins found in all living things. They help protect humans from bacterial infection and proteins related to anemia and neuromuscular disease in humans. The heart of the experiment was the use of a holographic microscope, which sent back images of the crystals while they were growing. The holographic microscope provided a capability to look at the physics involved in the growth of these types of crystals in order to better understand why some crystals grow better in space and some do not.
Foale and Kaleri also took time out from their schedule to answer questions from a syndicated talk show host from the Premiere Radio Networks and from students at the Howard Bishop Middle School in Gainesville, Fla.
Information about activities aboard the Space Station is available on the Internet at:
http://spaceflight.nasa.gov/
Information about Station science operations is available on the Internet at:
http://scipoc.msfc.nasa.gov/