March 15, 2008
Astronauts Overcome Robot’s Power Problem
Astronauts aboard the international space station overcame a worrisome power problem with their new, partially assembled robotic maintenance man late Friday, sending a wave or relief through his Canadian design team.
The fliers also floated into a newly installed Japanese module for the first time, finding the enclosure ready to occupy.
Dextre , a $209 million robot, and the 14-foot-long module, the station's first Japanese component, arrived aboard the shuttle Endeavour earlier this week. Both were transferred from the shuttle's cargo bay to the station late Thursday and early Friday. That's when it was discovered that Dextre could not receive electrical power for internal heaters that warm vital electronic circuitry.
Friday's accomplishments set the stage for a spacewalk late Saturday in which astronauts Rick Linnehan and Mike Foreman will resume Dextre's assembly by attaching two arms to his torso.
Dextre was developed to take on some of the space station maintenance work normally assigned to spacewalking astronauts.
"I guess I can say it's alive," Pierre Jean, the Canadian Space Agency's acting space station program manager, told a news briefing after the power problem was overcome. "A little bit of tension is relieved."
When fully assembled, Dextre will stand 12 feet tall with arms that stretch out 11 feet. The robot is so large, it must be stored outside the station, where the temperature swings are extreme.
"It was quite a relief, a real sense of success to see power applied," said Phil Engelhauf , NASA's chief flight director.
Efforts to begin the flow of space-station electricity to Dextre with a software patch early Friday failed to resolve the problem.
Working without a break, Canadian troubleshooters eventually tracked the source of the problem to a power cable within the pallet used to cradle Dextre's disassembled torso, arms and hands during Endeavour's launch.
The cable, engineers concluded, was not suited to handle both the flow of electricity and the exchange of data between the robot and a control panel inside the station.
As a workaround, Canadian engineers, decided to grapple the robot with the station's robot arm. The contact would establish a new path for electricity as well as the data exchange, they reasoned.
The strategy worked.
"Dextre has power," John Ira Petty, the commentator in NASA's Mission Control announced shortly after 9 p.m. CDT.
The pallet and the cable will return to Earth aboard Endeavour. Dextre will remain aboard the space station, plugged into one of several grapple fixtures like the mechanism on the end of the robot arm.
Also Friday night, three of the astronauts floated into the new module that will serve as an equipment locker for a larger Japanese lab called Kibo.
The Kibo lab is scheduled for launching aboard the shuttle Discovery in late May.
Station commander Peggy Whitson and Japanese astronaut Takao Doi led the way into the new module.
"This is a small step of one Japanese astronaut, but a giant entrance for Japan to a greater and newer space program," said Doi, who paraphrased the words spoken by American Neil Armstrong, when he became the first person to walk on the moon.
"We love our new room already," Whitson said. "We're very happy to have our new partner working with us more actively with the new module on board."
Japan becomes the last of the 15 nations involved in the American-led space station program to have a module added to the orbital outpost. When it arrives, the larger Japanese lab will house a variety of biology and physics experiments.
Doi, Whitson and Linnehan donned goggles and air masks as they floated in, garb to protect them from harmful dust and debris that may have been jarred loose during Endeavour's launch.
A third Kibo segment, an external experiment platform with a robot arm, is scheduled to arrive at the station in spring 2009.
Endeavour and a crew of seven astronauts lifted off early Tuesday on a 16 day mission, the longest shuttle assembly flight to the space station to date.
The linkup united 10 astronauts from four nations.
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