The astronauts also completed their initial outfitting of the station.
The astronauts initially could not remove caps covering the valves, but later forced them off and completed the task.
Shortly after the launching, the astronauts completed their main task, deploying the satellite.
It was the first time astronauts had successfully completed an unscheduled repair operation outside the shuttle since the program began a decade ago this month.
The astronauts will have completed four days in orbit, presumably deploying a radar reconnaissance satellite and conducting other military observation experiments.
The two astronauts completed the six-hour, 31-minute spacewalk at 19:53 UTC.
The astronauts today completed their scientific experiments and checked the performance of the steering rockets, which will orient and guide the descent.
They also must help astronauts successfully complete their tasks and carry out their missions.
During his first four flights, the astronaut logged more than 1 year, 3 months and 19 days in space and completed seven space walks.
After recovering their composure, both astronauts returned to their positions on Skylab and completed the EVA.