Astronauts fix ripped space station solar wing
Sunday, November 4, 2007
The solar panel captures sunlight to generate electricity, and is alive with more than 100 volts of electricity.
HOUSTON -- A spacewalking astronaut fixed a ripped solar energy panel on the international space station Saturday in a difficult and dangerous emergency procedure that allowed the crew to extend the wing to its full length.
Spacewalker Scott Parazynski installed improvised braces on the torn wing and clipped the snarled wires that had ripped it in two places as it was being unfurled Tuesday. He then watched as the crew deployed the wing to its full 115-foot length.
Astronauts inside slowly extended the wing, watching closely for more problems. The wing was about three-quarters unfurled when the crew noticed the damage on Tuesday.
"Excellent work guys, excellent," space station commander Peggy Whitson said after the wing was locked in place.
"Before we do the victory dance let's get Scott safely back to structure, and then we can all rejoice," Discovery commander Pamela Melroy said as the robotic arm started driving Parazynski back to the station.
Perched at the tip of a 90-foot robotic arm and boom extension, Parazynski worked at the far left end of the linked shuttle-station complex, about half a football field away from the pressurized compartments where the astronauts work and live.
The ugly snag involved a guide wire, two hinge wires and two grommets. Parazynski first clipped a hinge wire near the larger tear, using a special tool that looked like a hockey stick to make sure the panel didn't spring back and hit him.
The solar panel captures sunlight to generate electricity, and is alive with more than 100 volts of electricity, possibly as much as 160 volts.
"It's a bit of a reach here," Parazynski said as he stretched to cut part of the guide wire.
"It's what those monkey arms are for," Melroy said, referring to Parazynski's 6-foot-2 height.
As soon as Parazynski cut the guide wire, the approximately 90-foot stretch of it recoiled all the way down into a reel where fellow spacewalker Douglas Wheelock was controlling and monitoring it. To everyone's relief, it retracted smoothly. "Beautiful. Nicely done," Parazynski reported.
Parazynski's helmet camera sent close-up pictures of the damage to Mission Control and the space station, allowing the astronauts and experts on the ground to discuss the best way to tackle the damage on the gold-colored wing.
To reduce the risk of Parazynski being shocked by the electricity generated by the panel, all of the metal parts on his space suit were covered with insulating tape -- triple-taped, in fact -- as were all his tools.
Wheelock also kept a close eye on Parazynski and his tools, guiding him to lean back when he got a bit too close to the swaying wing.
Without repairs, the wing posed a structural hazard for the international space station. The damage could have worsened and the wing could have become unstable, possibly forcing NASA to cut it loose and lose a vital power source for future laboratories.
It was Parazynski's fourth spacewalk this mission and the seventh of his 15-year astronaut career.