March 16, 2008
Second Spacewalk Brings Robot Dextre to Life
Spacewalking astronauts brought a robotic handyman to life outside the international space station overnight, swinging the big partially assembled machine into a sitting position and attaching two arms.
Dextre, a $209 million Canadian creation, was designed to take on some of the repair duties normally assigned to spacewalking astronauts.
Astronauts Rick Linnehan and Mike Foreman transformed Dextre's pieces into a single gleaming 12-foot tall mechanism with outstretched arms and a menacing appearance.
"That was pretty impressive," said Linnehan, who tugged at Dextre's torso until the partially assembled robot was sitting up and ready for the arms to be attached. "It's really eerie out here, with this white humanoid-looking thing below me "” Mr. Roboto."
A spacewalk Monday night by Linnehan and astronaut Bob Behnken will equip Dextre with a toolbelt, lights and cameras.
The latest outing, which stretched seven hours into the early hours of Sunday, proved to be physically taxing.
"What we need is a jackhammer," Linnehan complained as they encountered the first of several balky bolts restraining Dextre's arms to a pallet.
"Do we have one of those?" asked Foreman, who fetched a pry bar instead.
Dextre's unassembled body arrived at the space station aboard the shuttle Endeavour last week. The U-shaped pallet holding the torso, arms, hands and other components was transferred to the orbital outpost using the station's robot arm.
Linnehan and Foreman floated over the work site just off the space station's main power truss. The two men groaned and grunted as they pried and pulled to loosen fasteners that restrained the first of the robot's arms.
"We may have to get medieval on Mr. Dextre," Linnehan huffed.
Bolts securing the robot's second arm required some prying as well.
The spacewalk was the second of three needed to fully assemble Dextre. Linnehan and Garrett Reisman attached hands to the robot's arms during the first outing late Thursday.
The overnight outing was the fifth spacewalk for Linnehan, a 50-year-old veterinarian who joined NASA's astronaut corps 15 years ago. It was the first for Foreman, a 49-year-old naval aviator, who signed up a decade ago.
The prying put the two men nearly an hour behind schedule at one point, but not out of sorts.
"I didn't think we would get this kind of workout," laughed Linnehan. "We really are longshoremen."
Frequently, the spacewalkers were asked to inspect the palms and fingers of their gloves for damage. The parade of spacewalks outside the station during the last two years is taking a toll on the protective garments. The inspections are intended to spot damage before it leads to a dangerous puncture.
"Are you guys ready to (spacewalk)?" station commander Peggy Whitson quizzed her colleagues before they floated out of the space station.
"Let's go," said Linnehan.
"Have fun out there, and get to work," said Whitson.
Dextre is so large he must be stored outside the station, where the temperature swings are extreme as the outpost sails in and out of sunlight.
After Dextre's arrival, the shuttle crew was unable to hook up electricity for the heaters that keep the robot's critical electronic circuitry from growing too cold.
Without heat, the robot's electronics would succumb to the low temperatures within four to five days.
Eventually, the problem was traced to an inadequate power cable in the delivery pallet. Mission Control overcame the problem by grabbing Dextre with the station's robot arm and routing power for heaters through the connection.
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