(AP) - Two spacewalking astronauts successfully rewired half of the international space station on Thursday, a job that when finished will allow the orbiting outpost to double the size of its crew and add two more labs in the coming years, reports Trend.
Flight controllers on the ground happily reported to the space station that power was flowing through two electrical channels hooked up by astronauts Robert Curbeam and Christer Fuglesang.
NASA immediately started powering up systems aboard a large section of the space station; the power had to be turned off for the spacewalkers' safety while they were handling the electrical connections.
The space agency also rushed to get the space station's ammonia cooling system operating again before the new electrical equipment overheated. It took less than an hour for the cooling system to start running smoothly.
"Today went as close to 'without a hitch' as you can possibly have a spacewalk go," John Curry, NASA's lead flight director for the space station, said at a briefing late Thursday.
It was the second spacewalk for Curbeam and Fuglesang since space shuttle Discovery arrived at the orbiting lab for a seven-day visit. The five-hour foray ended at 7:41 p.m., a full hour earlier than planned, and marked the 75th spacewalk dedicated to assembling the space station.
The rewiring job involved switching the space station from its old, temporary power source to its new one a pair of solar arrays that were delivered in September. The spacewalkers had to unhook three dozen electrical hoses and reconnect them. The astronauts also completed some housekeeping tasks.
This trip outside the spacecraft brings the total of spacewalking time dedicated to assembling the space station to 455 hours and 50 minutes, said NASA spokeswoman Nicole Cloutier.
During a short break, the spacewalkers watched shooting stars and the blaze of the aurora borealis, or northern lights phenomenon, which is caused by solar flares colliding with Earth's atmosphere. A solar flare earlier this week forced the astronauts to sleep in protective areas of the station and shuttle as a precaution.
"Gosh, they're beautiful," Curbeam said.
A third spacewalk set for Saturday will repeat the rewiring job, but on the flip side of the station's U.S. segment.
Before the start of the spacewalk, NASA flight controllers on the ground powered down sections of the station, losing some of the redundancy the space agency likes to have in its systems.
Half the lights in the station's U.S. laboratory went dark. Cameras at the station stopped working and some ventilation ducts were turned off. Communication between the U.S. and Russian sides of the space station was cut off. Even a smoke detector was turned off.
NASA is still keeping the option open to do a fourth spacewalk in which astronauts could manually fold up the old solar array, which failed to retract fully by remote control on Wednesday, but managers said they would try other options first.
The accordion-like 115-foot array, which had provided temporary power to the space station, retracted about halfway enough to allow the new pair of solar arrays to rotate.
The half-retracted array presents no danger, NASA said, but it needs to figure out how to overcome the hitch, as a second pair of arrays are scheduled to be retracted on a later mission.
Mike Suffredini, NASA's space station program manager, outlined a couple of ideas the space agency will try, starting on Friday. The hangup in the array is with a guidewire that is stuck in an eyelet, causing the array to billow.
NASA saw the problem on Earth, but gravity here helped fix it on its own. In space, the wire will need a little help, so NASA will try jiggling the array by moving a joint on that structure. It may also ask one of the astronauts to break a sweat using a bungee bar-like exercise device. Suffredini recalled an incident where NASA saw an array shaking and found the cause was astronaut Leroy Chiao working the device hard in his squats and lifts.
Because of the risks involved in spacewalks especially a spacewalk with a shock hazard involved and the mission's tight timeframe, Suffredini said a fourth spacewalk would be one of the last resorts.