Beginning at about 9 a.m. central time tomorrow (Thursday) and continuing each Thursday for the next six weeks, the Canadian-built Space Station Remote Manipulator System delivered on the most recent flight of the shuttle will be fully checked out in preparation for its first assembly assignment to install the station's airlock in June. Tomorrow's checkout will include cycling the capture device inside the arm's end effector and actually latching onto two different fixtures on the station: one on the Destiny Laboratory and one on the transfer tunnel between the lab and the Unity module.
Engineers on the ground have worked around the clock to restore full capability of the station's command and control computers since their mass storage devices exhibited failures in two of the three units during Endeavour's visit to the ISS last month. The computers - known as C&C (for command and control) 1, 2 and 3, act as the interface between station systems, the software and the hard drives that store and execute programs required for various activities, including the operation of the robot arm known as Canadarm2.
The current configuration shows C&C 2 as the primary computer, C&C 1 as a fully capable backup, and C&C 3 available as a standby without the use of a mass storage device. C&C 3's hard drive has exhibited the same potential failure characteristics as that of C&C 1. As a result, the crew built a spare computer this week and is ready to install it as a replacement for C&C 3, if needed.
Regardless, additional computer spare parts are being loaded aboard the next Progress supply vehicle scheduled for launch May 20 from the Baikonur Cosmodrome in Kazakhstan. It will dock May 22 to the back end of the Russian Zvezda module. The failed hard drive was returned aboard Endeavour May 1 and troubleshooting is ongoing as to what caused the failure.
With a new Soyuz vehicle now available at the ISS, Expedition Two Commander Yury Usachev and Flight Engineers Jim Voss and Susan Helms got back to work on board and set up for the robotics work that will utilize the Robotics Work Station in Destiny. They also completed repairs on the high-tech treadmill in Zvezda, restoring it to full use for the first time since it broke during the Expedition One mission.
Science activities continue onboard, scheduled during and around the robotics work and maintenance tasks.