Restoration of a failed computer system returned regular rhythm on the international space station Sunday, as two astronauts made the fourth spacewalk since space shuttle Atlantis docked with the outpost a week ago.
"We're slowly moving back into a normal mode of operations," station commander Fyodor Yurchikhin radioed Mission Control in Moscow.
The "normal mode" included the previously unscheduled fourth trip outside the space station to finish up tasks originally scheduled for last Friday's third spacewalk. Astronauts on the third spacewalk had the unplanned job of repairing a thermal blanket which had peeled back near Atlantis' tail during the June 8 launch.
The top priority for the spacewalkers, Patrick Forrester and Steven Swanson, was activating a rotating joint on the outpost's newest segment, allowing a new pair of solar wings to track the sun and provide power to the station.
The astronauts also set up a new camera stanchion outside the station's newest segment and planned to install a debris shield and a computer network cable between the United States and Russian sides of the space station during the planned 6 1/2-hour spacewalk.
At the end of the day, flight controllers on the ground planned to give the rotating joint a small test by moving it 5 degrees. A more thorough test to see if the solar arrays track the sun was in store on Monday.
Flight controllers on Monday also planned to test the space station's thrusters, which have not been used since the crash last week of the Russian computers, which control orientation and oxygen production.
Yurchikhin and Russian cosmonaut Oleg Kotov got four of the six computer processors operating again on Friday. The remaining two were brought back online on Saturday but then flipped back off to be "in cold standby mode" so that they could be used if needed.
"We can report that things are still improving," said flight director Holly Ridings.
With the exception of an oxygen generator, all of the space station systems that were powered down when the computers failed were back running.
Mission managers will decide after the thruster test whether Atlantis needs to spend another day at the outpost.
Atlantis is set to undock on Tuesday and land Thursday in Cape Canaveral, Florida.