Image shows a spacewalker at the end of a 50-foot (17-meter) boom that's attached to the international space station's robotic arm, in position for repairing a damaged solar array. Discovery astronaut Scott Parazynski is due to perform this operation for real on Saturday.
Crew members venture outside space station to attempt dangerous repairs
Hoping to save a ripped space station solar wing, astronauts ventured outside Saturday for one of the most difficult and dangerous spacewalking repairs ever attempted.
NASA officials and the astronauts in orbit worked day and night to plan every detail of the momentous repair mission. The snagged panel must be fixed before space station construction can continue.
"Go out there and fix that thing for us," station commander Peggy Whitson said just before spacewalkers Scott Parazynski and Douglas Wheelock floated out of the hatch.
"We will," Wheelock responded.
The plan calls for perching Parazynski at the end of a 90-foot (27-meter) robotic arm and boom extension for a 45-minute ride to the damage site.
There, he will tinker with what amounts to a damaged electrical generator. The solar panel will be teeming with more than 100 volts of electricity, possibly as much as 160 volts.
To save the solar wing, Parazynski needs to clear whatever snagged the panels and caused the wing to tear in two places while it was being unfurled Tuesday. He will not know what he's up against until he sees the damage up close.
"We've collected a lot of video, a lot of still photography.
But nothing's going to be like the moment when Scott Parazynski actually puts his eyes on this area of interest, on this potential guidewire snarl," flight director Derek Hassmann said Friday.
As it is now, the wing poses a structural hazard for the international space station. The damage could worsen and the wing could become unstable, possibly forcing NASA to cut it loose and lose a vital power source for future laboratories.
Once Parazynski has cleared the snag -- possibly by moving the guidewire or cutting it and letting it wind up at the base of the tower -- he plans to install several homemade braces so astronauts can deploy the wing to its full 110 feet (33 meters). It is about 75 percent deployed now.
Astronauts made the braces from aluminum sheets and insulated tape aboard the linked shuttle-station complex.
Wheelock will be nearby to guide Parazynski and the astronauts operating the robotic arm. Italian astronaut Paolo Nespoli will choreograph the outing from inside the complex.
It will be Parazynski's fourth spacewalk this mission and the seventh of his 15-year astronaut career.
He and Wheelock will wear partial mittens over their gloves for extra protection. Wheelock pierced the outer layer of a glove near the end of Tuesday's spacewalk, the third time in less than a year that a spacewalker tore a glove on something sharp at the space station.