Mission controllers in Moscow fired pyrotechnic devices that activated spring pushrods to eject the 20-foot-long instrumentation and propulsion segment of the Pirs Docking Compartment at 10:36 a.m. Central time today. The segment moved away from the station at a rate of about 4 meters per second until it reached a point far enough away to fire its control system jets without contaminating the station. It then moved ahead and above the station to a distance of 24 kilometers when its thrusters were commanded to fire in a deorbit maneuver sending it into the atmosphere to burn up upon reentry. Left behind is the 16-foot long, 4-ton Pirs, which will serve as a new port for future Russian vehicles arriving at the station and as an airlock from which spacewalks will be conducted from the Russian segment of the outpost.
Today's activity sets the stage for the first space walk from Pirs by Dezhurov and Tyurin on Oct. 8. On that space walk, the pair will use Russian Orlan space suits to connect power and data cables between the Docking Compartment and the Zvezda Service Module. A second space walk is planned Oct. 14, and a third in early November.
Flight control teams in Houston and Moscow are working on a plan to address this week's shutdown of the Russian segment oxygen generation unit called Elektron, and an air-conditioning unit in Zvezda. Russian flight controllers are reviewing data in an attempt to determine the causes of the shutdowns and are working with their American counterparts to provide backup oxygen generation capability until the two Russian components can be repaired or replaced. The crew has about a week's worth of oxygen already in the station atmosphere, and has ample stores of oxygen from the gas tanks on the Quest Airlock as well as solid fuel oxygen candles to last for months. Other maintenance work completed by the crew this week included the replacement of 10 smoke detectors in the Zvezda module. The Elektron shutdown will have no impact on station operations.
Meanwhile, at the Baikonur Cosmodrome in Kazakhstan, a replacement Soyuz return spacecraft is being readied for launch to the station on Oct. 21. The station crew will relocate its current Soyuz spacecraft on Oct. 19 from its present location at an Earth-facing port on the Zarya module to the new docking port on Pirs to clear the way for arrival of the fresh Soyuz and a taxi crew. Commander Victor Afanasyev, Flight Engineer Konstantin Kozeev and Flight Engineer Claudie Haignere will arrive at the station Oct. 23 for an eight-day stay.
The orbiting trio has expanded its scientific investigations into new areas, including a study of the ability of certain chemical compounds to impede the formation of kidney stones. Culbertson set up and served as the first test subject for the experiment this week, which involves ingesting pills that contain either the active compound or a placebo in an effort to determine the value of the countermeasure on a small population. Urine samples are collected, as are detailed information about the crewmember's fluid and food intake. The other two crewmembers also will participate in the experiment. The crew also continued testing the Active Rack Isolation System through a series of "shaker" tests of its ability to protect sensitive experiments from vibrations caused by everyday crew activity. Oversight of science investigations on the station from the ground is handled by the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, AL. the Human Research Facility is managed by the Johnson Space Center.
The station is orbiting at an average altitude of 240 statute miles (385 km).