Commander Yury Usachev and Flight Engineer Jim Voss will open hatches in the Zvezda module beginning Friday morning about 9:30 to reposition a docking mechanism in preparation for the arrival of a Russian docking module later this year. They climbed into their Russian spacesuits Tuesday, entered the transfer compartment and conducted a practice session for the task, which is budgeted to take about 30 to 40 minutes.
As a precaution, hatches will be closed at various locations on the station so that the small, ball-shaped transfer compartment can be depressurized. Flight Engineer Susan Helms will remain in the Zarya module throughout the Extravehicular Activity (EVA).
Meanwhile, the Canadian Space Agency today planned to send computer commands to the station's robot arm, called Canadarm2, to attempt to pinpoint the cause of a problem with one of its seven joints in the redundant, or backup mode. Though the primary system of the arm works perfectly, the arm must have a prime and backup operating system functioning prior to the launch of Atlantis delivering the Joint Airlock to the complex.
The Canadarm2 is required for the grapple of the airlock in Atlantis' cargo bay and its installation on a docking port of the Unity module. The 25,000-pound airlock will allow future station-based spacewalks to be conducted in U.S. and/or Russian spacesuits. The Shuttle robot arm cannot reach the Airlock installation location.
In parallel, a software patch is being developed that actually can mask, or inhibit, the use of the suspect shoulder pitch joint allowing operation of the arm in six of the seven degrees of freedom. Again, the arm works fine on its primary string and, in fact, yesterday was maneuvered to what likely will serve as its stowed, or cradled position, with each end firmly attached to a grappling pin on the outside of the Destiny laboratory and one on the tunnel adapter leading to Unity.
Until the Canadarm2 evaluation is completed at week's end, shuttle and station managers will not firmly decide on the launch dates for the next two assembly missions. However, at present the next flight is tentatively slated for launch in early July pending resolution of the shoulder pitch joint problem and the conduct of a "dry-run" of the airlock installation. The follow-on flight remains scheduled for early August carrying a replacement crew for Expedition Two.
The Expedition Three crew of Commander Frank Culbertson and Flight Engineers Vladimir Dezhurov and Mikhail Turin today completed training at Star City outside Moscow.