Mission Specialists Bob Curbeam and Christer Fuglesang began their second spacewalk at 1:41 p.m. CST. Less than two hours later, they had the first half of the stationís permanent power system Ė channels two and three Ė up and running, taking advantage of power generated by the solar arrays delivered in September.
The second half of the stationís power system Ė channels one and four Ė will be reconfigured during the missionís third spacewalk Saturday. Once thatís done, the stationís power system will be in its assembly complete configuration, ready for the addition of more solar arrays and science modules next year.
Before the spacewalkers swapped the cable connections, station flight controllers had to shut down about half of the stationís systems, including some lights, communication gear, ventilation fans and back-up computers. They started the power down just before 2 p.m., and by 3:45 p.m., were powering up main bus switching units for the first time ever and activating power channels two and three. By 4:30 p.m., one of two external thermal control system loops was actively shedding excess heat into space, and the direct current-to-direct current converter units were regulating power voltages.
The spacewalkers headed out the hatch of the Quest airlock this afternoon about 30 minutes ahead of schedule, and made it through their tasks quickly enough to pick up another thirty minutes. They finished at 6:41 p.m., an hour earlier than planned and exactly five hours after they started. Expedition 14 Flight Engineer Suni Williams and STS-116 Mission Specialist Joan Higginbotham operated the station's robotic arm in support of the spacewalk.
Before heading back into the station, Curbeam and Fuglesang also relocated two small handcarts that run along rails on the stationís main truss, put a thermal cover on the stationís robotic arm and installed bags of tools for future spacewalkers.
Discoveryís crew is scheduled to go to sleep at 1:47 a.m. Friday. Flight Day 7 begins with a wakeup call at 8:47 a.m. The crew will spend the day transferring supplies and equipment from Discovery to the station, participating in a news conference and enjoying some off-duty time.