The crew also tested the four 630-pound gyroscopes in the truss, called Control Moment Gyros, which will be used to orient the ISS as it orbits the Earth. The crew spun up the gyros to about 100 revolutions per minute, largely to confirm their speed and power consumption. They will ultimately be spun up to about 6,000 revolutions per minute once they assume attitude control of the ISS following the arrival of the U.S. Laboratory Destiny, scheduled for January.
Mission Specialists Bill McArthur and Leroy Chiao used a laptop computer to conduct the tests, which included turning on the gyroscope heaters. The heaters are designed to keep the gyros from being damaged by the cold of space.
Those tests, and the transfer of supplies into the Russian Zarya Module took longer than expected. As a result, the crew's final departure from the Station's Unity module was delayed until Friday morning, which, in turn, will delay Discovery's undocking from the ISS for about ninety minutes to 10:09 a.m. CDT time Friday. The later undocking time will have no impact on other Shuttle operations for tomorrow.
Pilot Pam Melroy and Mission Specialist Jeff Wisoff took samples from surfaces in Zarya to study the module's environment. Melroy and Wisoff also unclogged a solid waste disposal system in the Shuttle's toilet, which was restored to full operation after a brief interruption in service.
In other news, NASA and Russian officials announced today that the Expedition One crew will be launched on a Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan on Tuesday, Oct. 31 at 1:53 a.m. central time, 10:53 a.m. Moscow time. The one day adjustment in the launch date was made to accommodate the Soyuz rendezvous requirements needed to reach the ISS two days after liftoff. Docking of the Soyuz and the Expedition One crew, Commander Bill Shepherd, Soyuz Commander Yuri Gidzenko and Flight Engineer Sergei Krikalev is now set for Thursday, Nov. 2, at 3:20 a.m. central time, 12:20 p.m. Moscow time.
Discovery's astronauts will begin an eight-hour sleep period at 9:17 p.m. CDT tonight and will be awakened at 5:17 a.m. Friday to prepare for their undocking.
Discovery continues to orbit the Earth in good shape with landing scheduled for Sunday afternoon at the Kennedy Space Center.