With Indian-American astronaut Sunita "Suni" Williams operating the International Space Station's robotic arm, a pair of space-walkers turned electricians to rewire her new home in space.
During a five-hour excursion, which ended at 6.11 am on Friday, Robert Curbeam and Christer Fuglesang, on their second space-walk, changed the station's power system into a permanent one - a task that would allow doubling the size of its crew and add two more labs in the coming years.
Mission control at Houston happily reported to the space station that power was flowing through two electrical channels hooked up by the space duo. "We've got good news. No, it's not good news, it's great news," said astronaut Stephen Robinson.
"Awesome!" said lead space-walker Curbeam.
"Excellent. Excellent," said pilot William Oefelein, who was coordinating the space-walk from inside the orbiting outpost, with resident flight engineer Williams and mission specialist Joan Higginbotham minding the robotic arm.
The National Aeronautics and Space Administration (NASA) immediately started powering up systems aboard a large section of the space station. The power had to be turned off for the space-walkers' 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.
As the space-walk began at 1.11 am on Friday, Curbeam and Fuglesang rewired two of the station's four power channels. After they finished the connections, flight controllers began sending commands at 3.15 am on Friday to power up the electrical systems in their new configuration.
The remaining two channels will be rewired during the mission's third space-walk slated for Saturday to bring power generated by the P4 solar arrays on line for use by the station's systems and prepare for more arrays to be added next year.
The duo then turned their attention to the relocation of two crew equipment translation aid carts. This cleared the way for the station's mobile transporter rail car to move down the station's rail system to the S1 truss at a later date in preparation for another shuttle mission next spring. The final task of the space-walk was the rerouting of cables on the Z1 truss.
In other activities, the visiting and resident astronauts continued cargo transfers between space shuttle Discovery and the station.
Managers and engineers continue to explore options relating to the retraction of the port wing of the station's P6 truss. The wing was partly folded on Wednesday and all but 17 of its 31 bays were retracted.
That was enough to allow the P4 solar arrays to begin their paddle-wheel-like rotation to track the sun for optimal power production. A decision on whether any further action will be taken to fully retract the array during the Discovery mission is not expected before Saturday.
The half-retracted accordion-like 115-foot array, which had provided temporary power to the space station, presents no danger, NASA said. In a worst-case scenario, it could be jettisoned.
"It's a little disappointing with the solar array, but folks...understand you're going to have a little hiccup," said Joel Montalbano, a space station flight director. "NASA probably does its best with their back against the wall."
During a short break, the space-walkers 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.
"Gosh, they're beautiful," Curbeam said.
Throughout the outing, NASA kept a close eye on radiation levels near earth that have been high as a result of unusually powerful solar flares last week and again on Wednesday. The shuttle and station crews have spent the past two nights sleeping in protected areas of their spaceships in case X-ray and heavy particle emissions from the sun began passing through the metal hulls.
Discovery arrived at the space station on Saturday for a weeklong stay. It is scheduled to land on earth on December 21 at the Kennedy Space Centre in Florida.