Flight controllers today put the finishing touches on plans for the fourth spacewalk recently added to the mission. On board the Space Shuttle Discovery and the International Space Station astronauts finished transferring the bulk of supplies between the two spacecraft.
Monday's spacewalk is set to begin at 1:12 p.m. as veteran spacewalkers Robert Curbeam and Christer Fuglesang go out to continue attempts to retract a solar array wing. The team has allotted six hours and 30 minutes for the spacewalk, but hopes to have the work completed in about four hours and 30 minutes.
Plans call for Curbeam to work from the end of the station's Canadarm2 to reach specific areas of the solar array. Today the arm was moved atop its mobile platform into position on the truss railway to support the spacewalk. From the arm, Curbeam can use Kapton tape-insulated tools, including a scraper, needle-nose pliers and an extended bail puller to free up the array for retraction.
The techniques designed to fix the array include lightly pulling on guide wires along the length of the panels, flipping grommets that the wires may be hung up on and gently pushing on hinges in the panels to allow them to fold up.
Fuglesang will work from the truss to assist Curbeam and shake the solar array, as was done in Saturday's spacewalk, if needed. He will also take photographs of the solar array wing on the other side of the truss to document its configuration before its retraction on the next joint shuttle and station mission.
After the crewmembers work on the array and change its configuration they will move clear as the crew inside the shuttle and station complex attempts to retract the array one bay at a time.
Astronauts Sunita Williams and Joan Higginbotham will operate the station's robotic arm during the spacewalk. Pilot Bill Oefelein will serve as the spacewalk coordinator.
In other activities, transfer of equipment and supplies between the spacecraft is almost complete. Crewmembers and flight controllers planned for the last bit of transfer to include tools and equipment remaining after the final spacewalk. That work is set to be completed before Discovery undocks from the station Tuesday afternoon.
Shuttle Commander Mark Polansky and astronauts Nicholas Patrick, Curbeam, Oefelein and Higginbotham participated in media interviews at 6:27 p.m.
This evening, the crew has time to review the spacewalk plans before Fuglesang and Curbeam enter the Quest airlock for their third overnight campout together. Lowering the pressure of the airlock to 10.2 psi is part of a process to avoid any possibility of the two spacewalkers developing decompression sickness in the relatively low pressure of their spacesuits. The suits are pressurized to a little less than 5 psi.
The crew goes to bed at 12:17 a.m. Monday and will awaken at 8:17 a.m. for another spacewalk day.
The next STS-116 status report will be issued Monday morning or earlier if events warrant.
