Fixing A Leak

Expedition 8 Commander Michael Foale reestablished a vacuum between the Destiny Laboratory’s science window’s two panes of optical-quality glass over the weekend. The window work was associated with continuing repairs following a small pressure leak detected on the International Space Station in January.

Foale, with help from Flight Engineer Alexander Kaleri, completed a procedure to remove any condensation that might have accumulated between the glass panes during removal a damaged flex hose used to keep the area between the window panes at vacuum. The final remaining steps in the repairs are construction of a cover to protect the hose against inadvertent contact and installation of a new jumper hose that was delivered by the resupply ship Progress 13.

Kaleri continued to troubleshoot intermittent failures of the Elektron oxygen generation system in the Zvezda service module. That system, which pulls oxygen from water, is one of several mechanisms used to provide breathing air. Today, Kaleri and flight controllers in Moscow restarted the system repeatedly in an effort to eliminate bubbles in the system. While repairs are ongoing, the Station’s atmosphere has been repressurized using oxygen from the Progress spacecraft. Oxygen-generating canisters also are available, but are not being used at this time.

The first part of the week consisted of time off and light duty for Foale and Kaleri after last week’s first-ever two-person spacewalk without a crew member inside the Station. The pair completed almost three-quarters of the tasks planned before Kaleri reported that drops of water were beginning to form inside his helmet visor and that his suit temperature was a little warm. After cutting short the spacewalk, the pair quickly detected a kink in one of the tubes in Kaleri's liquid cooling garment. The kink was straightened out and water began to flow normally.

The crew also worked with several science experiments, notably the PromISS protein crystal growth experiment. Wednesday, they stowed the experiment sample in the Aquarius incubator after a successful 30-day growth cycle.

In Thursday’s regularly scheduled ISS Mission Management Team meeting, US and Russian managers discussed the status of a minute pressure decay in the two helium systems that pressurize the Soyuz 7 vehicle’s propellant tanks and lines. The pressure decay was first noted on System 2 when the Soyuz arrived at the Station in October, and was confirmed on System 1 during a thruster test in preparation for last week’s spacewalk. Russian flight controllers have concluded that the decay poses no concern. The decay was extremely small and there are no plans to change normal entry and landing procedures.

Meanwhile, flight controllers in Houston reported seeing slight momentary increases in electrical current and vibration readings from one of the Station's Control Moment Gyroscopes (CMG) earlier this week. The readings were seen on CMG 3, one of three operating CMGs on the Station, following normal steps taken as part of a Station altitude reboost performed Tuesday using thrusters on the docked Progress cargo craft. All three CMGs continue to function well now with normal current indications, although flight controllers continue to evaluate the readings seen in recent CMG operations. Powered by electricity generated by the Station's solar arrays, the CMGs provide continuous orientation control of the Station without using the Station's limited fuel supply.

FMI: www.nasa.gov