Discovery and International Space Station crew members will conduct their fourth spacewalk of the week today, an excursion aimed at freeing a snagged, partially retracted station solar array so it will fully fold properly.
Astronaut Bob Curbeam and Christer Fuglesang, a European Space Agency astronaut from Sweden, will venture outside the station at 1:12 p.m. CST. It will be Curbeam's fourth spacewalk of the mission, more than any astronaut has performed during a single shuttle flight, and it will be Fuglesang's third. Using a variety of specially prepared, tape-insulated tools, they will work to complete the retraction of the port solar array wing of the station's P6 truss.
Curbeam and Fuglesang spent the night in the station's Quest airlock in a procedure called a "campout." The air pressure in the compartment was reduced to 10.2 pounds per square inch to assist in purging nitrogen from their bodies, a measure that helps prevent decompression sickness.
The shuttle crew was awakened at 8:17 a.m. CST to the song "Good Vibrations," performed the Beach Boys. The song was played for the entire crew in honor of the vibrations the spacewalkers may create today to attempt to free the balky solar panels. As part of the suite of potential activities they have on hand to assist with folding the array, Curbeam and Fuglesang will shake the solar blankets by pushing on the boxes into which they fold. If needed, the spacewalk could last as long as six and half hours.
Curbeam will be on the station's Canadarm2 robotic arm during the spacewalk. He will be equipped to work on two problems believed to be experienced by the array. One is the apparent jamming of the guide wires in the grommets designed to guide them. The other is some backward, balky folding of hinges between solar panels that has been seen during attempts at retraction. As those issues are dealt with by the spacewalkers, crew members inside will send commands to further fold the array.
Fuglesang will be on the P6 truss. He will push the blanket boxes into which the arrays fold to shake the wing. He also will take pictures, including some of the P6 starboard solar wing. That wing is to be retracted on the next shuttle flight to the station. The photos taken by Fuglesang will assist in the planning of that task.
Williams and Discovery Mission Specialist Joan Higginbotham will operate the station's robotic arm during the spacewalk. Pilot Bill Oefelein will serve as the spacewalk coordinator, or intravehicular officer, inside the spacecraft.
The transfer of equipment and supplies between the shuttle and station will continue today as well. Almost all of the 4,292 pounds brought up aboard Discovery has been moved to the station, and the loading of 3,725 pounds of gear in those areas for return to Earth is nearing completion as well. Discovery's undocking from the station is now planned for 4:09 p.m. CST on Tuesday. Discovery is planned to land at the Kennedy Space Center, Florida, at 2:56 p.m. CST. on Friday.
The next STS-116 status report will be issued Monday evening, or earlier if events warrant.
