Indian-American astronaut Sunita Williams and International Space Station commander Mike Lopez-Alegria went on a seven-hour, 55-minute spacewalk in the first of an unprecedented three outings in nine days.
The duo returned to their home in space through the Quest airlock at 4:39 am IST on Thursday after working on the reconfiguration of the station's power and cooling systems, US space agency NASA said.
They are scheduled to take their second space walk on February 4 and the third on February 8.
While flight engineer Williams — wearing an all-white suit — reconfigured electrical connections, Lopez-Alegria — in the lead in a suit with red stripes — worked at the "rats' nest", an area near the base of the Z1 Truss with numerous fluid and electrical connections.
As the spacewalkers stood by, the ground control retracted the starboard radiator of the P6 Truss.
After retraction, they installed six cable cinches and two winch bars to secure the radiator and then installed a shroud over it. Williams and Lopez-Alegria then moved to the Early Ammonia Servicer on the P6 Truss.
It provided a contingency supply of ammonia for the temporary Early Ammonia System. With the permanent cooling system working, it is no longer needed.