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Astronauts ready for Tricky Solar Wing Surgery

With NASA's go-ahead, astronauts are gearing up for a tricky solar wing repair at a far end of the International Space Station (ISS) tomorrow.

Crewmembers scrounged around the orbital laboratory yesterday for supplies, crafting "cuff links" with them that will button up two rips in the solar array wing. Today, mission controllers here at Johnson Space Center (JSC) sent astronauts on another scavenger hunt to find tools for repairing the power-generating blanket.

The space station now confronts two major threats to its power supply, both of which arose during the STS-120 mission. In addition to the maimed solar wing, which generates electricity but is structurally unstable, spacewalker Dan Tani discovered unusual metallic grit in solar-array-orienting gears on Oct. 28.

Since the solar array tore during its deployment on Oct. 30, however, mission managers abandoned inspecting the gears and scrambled to make the solar wing fix a top priority.

"We've had at least three or four extra teams running throughout the shifts," said Heather Rarick, ISS flight director, of the efforts to finish detailed plans for tomorrow's spacewalk. "It's just been a fantastic effort."

Astronauts took the changes in stride as well, offering up their sparse free time to outfit the space station's newest room as well as create the solar wing-saving cuff links. Today, crewmembers prepared Parazynski's ride--a 90-foot (27.4-meter), extended robotic arm--to the damaged solar wing.

"We know and understand how hard you guys are working down there," spacewalker Doug Wheelock told mission controllers last night. "We're ready to execute."

Wheelock will accompany Parazynski during the fourth and now final spacewalk of the mission. A fifth spacewalk was planned for Sunday, but mission managers cancelled the operation to focus on hashing out plans to repair the 4B solar wing, which is attached to the Port 6 truss section of the space station.

Risky repair
Mission managers said yesterday that Parazynski faces multiple risks while tacked onto the extended robotic arm.

Beyond electrocution from the solar array wing, which can generate 110 volts of electricity at 90 amperes in full sunlight, Parazynski will be an hour away from the safety of the airlock--significantly farther than astronauts are during most spacewalks.

David Wolf said the spacewalk is necessary to ensure the future completion of the space station.

"There comes a time when the station needs repaired, one-time events where we--with good mitigation and knowledge--accept high risk," Wolf said. "And that's one of them." Wolf added that addressing the risks outright leads to better controlling them and preparing astronauts like Parazynski to avoid danger.

"Our job is to think of all those possible ways where a bad outcome could occur," Wolf said, "and be sure that every hazard is mitigated and handled."

NASA awoke the 10 free-floating astronauts this morning to the song "World" by Five for Fighting. "We're looking forward to another great day working with you and building the space station," Wheelock said as he awoke, dedicating the tune to hard-working crews on the ground.

Discovery and its seven-astronaut crew are slated to leave the orbital laboratory on Nov. 5 and land at Kennedy Space Center on Nov. 7, weather permitting. NASA officials said that the crew has enough supplies to stay docked for the ISS for two more days beyond Monday, should the need arise.

And it might. Mission managers said that if Saturday's spacewalk effort fails to repair the solar wing, mission managers said they will resurrect the fifth spacewalk for a second try on Sunday or Monday.

About Orbital Laboratory
The Manned Orbital Laboratory (MOL) was part of the United States Air Force's manned spaceflight program, a successor to the cancelled X-20 Dyna-Soar project. It was announced to the public on the same day that the Dyna-Soar program was cancelled, December 10, 1963. Initially, the MOL was intended to prove the utility of man in space for military missions. However, the program was redirected in the mid-1960s and developed as a space station used for reconnaissance purposes. The space station used the Gemini B spacecraft that was derived from NASA's Gemini program. The contractor for the MOL was the Douglas Aircraft Company. The Gemini B/MOL craft was externally similar to NASA's Gemini spacecraft although it suffered several modifications. The most obvious was the addition of a circular hatch through the heat shield to allow passage between the spacecraft and the laboratory.