Commander Ken Bowersox and NASA ISS Science Officer Don Pettit on Monday installed a new Pump Package Assembly (PPA) in the Moderate Temperature Control Loop (MTL) of the Destiny Laboratory's Thermal Control System, which provides cooling for the station's avionics control boxes. The old pump had failed the previous day. The new pump was started Tuesday but one of its check valves stuck open. Thursday, the crew and flight control team worked together to reseat that check valve, get the PPA running, and verify the MTL for operation. Cooling for the Lab's systems was provided through the TCS's Low Temperature Loop during the interim.
While the Americans were installing the new pump Monday, Flight Engineer Nikolai Budarin upgraded the Russian computer system's control software. Wednesday, the crew helped ground controllers respond to a computer-commanded power down of many station systems and science equipment. After the Russian computer system was rebooted, a Russian terminal computer in the Zvezda module was unable to communicate with U.S. Guidance, Navigation and Control (GNC) computer #2, which was in control at the time. When the two computers couldn't talk because of the ongoing software transition, a routine handover of station attitude control to the Russian segment was not possible. This prompted U.S. computers to begin powering down non-critical systems. Flight controllers in Houston restarted all systems within hours, station attitude control was never lost an there was no damage to any station system. The trio also started reviewing a timeline for the second spacewalk of their tour of duty, now scheduled for April 8. Bowersox and Pettit, who conducted the first spacewalk of the mission on Jan. 15, are preparing for another excursion to several sites along the station's Integrated Truss Structure where they'll reconfigure power connections, release a light stanchion on one of the Crew Equipment Translation Aid (CETA) carts, provide a second power source for one of the station's control moment gyroscopes, and secure thermal covers on quick disconnect fittings for the station's thermal control system. This will be the 51st spacewalk in support of station assembly, the 26th to originate from the station itself.
After weeks of careful troubleshooting for the cause of a power failure in the Microgravity Science Glovebox, an inquiry board from the European Space Agency has approved a return to normal operation for the experiment facility in the Destiny Laboratory. The apparatus, which provides a controlled environment for microgravity science experiments involving fluid, fumes and flames, has been inoperative since the failure of two power-control boxes in late November. Repaired components were installed in early February, but after being restarted the MSG exhibited signs similar to those seen just prior to its failure late last year. Since then, Pettit has worked with the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, Ala., and ESA specialists to complete a detailed series of tests, and they have uncovered no failures or unusual current draws. Next week, MSG will be fully powered and evaluated, and then could be cleared for full operation. Tuesday morning, Bowersox and Pettit talked about the goals of their mission and their progress in achieving them with WISH-TV in Indianapolis (Bowersox is from nearby Bedford, Ind.) and Pettit's hometown newspaper, the Silverton (Ore.) Appeal-Tribune.