With half the International Space Station's electrical system rewired, the crew of Space Shuttle Discovery gets half a day off today before they finish the job during a third spacewalk set for Saturday.
Mission Specialists Bob Curbeam and Christer Fuglesang rewired channels 2 and 3 of the station's power system in a five-hour spacewalk Thursday. A similar task will be done with the two remaining station power channels, channels 1 and 4, on Saturday. However, for Saturday's spacewalk, Curbeam will be joined by International Space Station Flight Engineer Suni Williams for the outside work while Fuglesang will coordinate activities inside the spacecraft. Once the third spacewalk is complete, power will be fully online from the station's P4 Truss solar array wings, which were installed in September. At that point, the station's power system will be ready for additional expansion with more arrays and new laboratories to be delivered next year.
Discovery Commander Mark Polansky and his crew-Pilot Bill Oefelein and Mission Specialists Nicholas Patrick, Joan Higginbotham, Thomas Reiter, Curbeam and Fuglesang?were awakened at about 8:52 a.m. CST to the song "Low Rider," performed by War, and played for Oefelein.
Discovery and the station are in good condition. Discovery is currently maintaining the orientation of both the station and shuttle using the shuttle steering jets, a function it began performing during preparations for the spacewalk on Thursday. Control of the station's orientation was transferred to Discovery on Thursday as part of the normal preparations of the station's power system for the rewiring job. The station usually uses its own control moment gyroscopes to maintain its orientation, without having to use fuel.
Originally, control of the station's orientation was to be transferred back to those gyroscopes late Thursday after the spacewalk tasks were completed and station systems powered up. However, problems were experienced as that transfer was attempted. Flight controllers believe the problems were due to a higher than usual amount of atmospheric drag currently experienced by the station due to recent solar activity. They may attempt to transfer control of orientation back to the station again today, although the shuttle thrusters can be used if needed for that purpose through the rest of the mission. If necessary, the station has thrusters that can be used for orientation control as well.
During the first half of their day, the astronauts will transfer supplies and equipment between the station and shuttle. At 1:07 p.m. the two European Space Agency astronauts, Fuglesang of Sweden and Reiter of Germany, will participate in a VIP call from Swedish dignitaries. At 2:47 p.m. all 10 astronauts and cosmonauts on the shuttle/station complex will conduct a news conference with reporters in the U.S. and Europe. The shuttle crewmembers will be off duty the last half of the day.
Station Commander Michael Lopez-Alegria and Flight Engineer Mikhail Tyurin are scheduled for interviews with KNX Radio, Los Angeles, and National Public Radio at 4:27 p.m. CST.
Engineers investigating the difficulties with fully retracting the port-side solar array wing of the station's P6 Truss believe a guide wire may be snagged in a swiveling grommet on one of the array's panels. The snag could be keeping the panels from folding up completely. The array remains almost halfway retracted as it has been since Wednesday. Early this morning, station flight controllers commanded the array through a series of "wiggle" tests, swiveling the wing 10 degrees at a time repeatedly to see if that would help the situation. They are continuing to evaluate the results of those tests and to investigate options for further work with the array, including the potential to add a spacewalk to latter part of this mission. Options also may include some additional troubleshooting commanding that could be performed with the array during the crew's day today.
The next STS-116 status report will be issued Friday evening or earlier if events warrant.
