March 18, 2008

Spacewalkers Finish Assembly of Dextre Robot

Spacewalking astronauts wrapped up the assembly of a robotic handyman outside the international space station late Monday, equipping the 12-foot tall humanoid with a tool kit, camera and lights.

The outing by astronauts Rick Linnehan and Bob Behnken drew to a close after midnight, stretching to nearly seven hours.

The $209 million Canadian mechanical maintenance man, nicknamed Dextre, was delivered to the space station in pieces aboard the shuttle Endeavour last week. His hands, arms and torso were fastened together during two previous spacewalks.

Dextre's new cameras and lights will serve as the eyes for astronauts positioned inside the station or the operators in Mission Control who issue the commands that make Dextre move. He was developed by Canadian engineers to take over some of the space station maintenance tasks normally assigned to spacewalking astronauts.

"Happy St. Patrick's Day, and have a good (spacewalk)," colleague MIke Foreman radioed the two men as they floated from the station's airlock to work with Dextre and transfer spare parts and experiment from the shuttle's cargo bay to the station.

Dextre will be moved from his assembly site on the station central power truss to a parking place on the outside of the American science module today. There, he will wait for his first assignment.

Monday's spacewalk required plenty of muscle as Linnehan worked from the tip of the station's 57-foot-long robot arm and Behnken floated next to Dextre. Though they got off to a early start, the spacewalkers fell about 40 minutes behind schedule as they bolted a tool kit to Dextre's right side and installed a camera and light fixture. Working more than 200 miles above the Earth, Linnehan and Behnken stopped to watch the brilliant flashes of lightning from a line of thunderstorms off the west coast of South America.

As he turned to the south, Linnehan also spotted something unusual.

"That's definitely a satellite, two satellites, three satellites," he radioed. "Wow."

The spacewalkers were less successful with a pair of experiments they attempted to attach to the outside of the station's European science lab. A jam in the latching mechanism prevented Behnken from installing a pair of suitcase-sized containers with samples of spacecraft construction materials. The samples were to be exposed for a year, then collected by spacewalkers so the effects of solar radiation, temperature swings and other corrosive conditions in space can be studied.

Linnehan and Behnken also transferred a collection of spare parts for the station from Endeavour. Those included two power-switching devices that are part of the battery-charging system on the station's solar power network and spare parts for the robot arm.

The outing was the first for Behnken, a 37-year-old Air Force major with a doctorate in mechanical engineering. It was the sixth for Linnehan, a 50-year-old veterinarian. Behnken joined NASA's astronaut corps eight years ago and Linnehan 16 years ago.

Endeavour launched March 11 on a 16-day mission, the longest shuttle assembly flight to the station to date. More spacewalks are planned for Thursday and Saturday nights.


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