European Space Agency astronaut Luca Parmitano and U.S. space agency NASA astronaut Andrew Morgan wrapped up their spacewalk at 1:35 p.m. U.S. Eastern Time (1835 GMT).
The six-hour-and-33-minute spacewalk started as the astronaut duo switched their spacesuits to battery power at 7:02 a.m. U.S. Eastern Time. This is the second of a series of spacewalks to replace a cooling system on the Alpha Magnetic Spectrometer (AMS).
The two astronauts successfully cut a total of eight stainless steel tubes, including one that vented the remaining carbon dioxide from the old cooling pump.
It came after they removed a debris cover on the AMS and installed handrails in preparation for the subsequent spacewalks during their first extravehicular repair work on Nov. 15.
During today's spacewalk, the crew members also prepared a power cable and installed a mechanical attachment device in advance of installing the new cooling system.
It cleared the way for their next task on Dec. 2 when they plan to bypass the old thermal control system by attaching a new one off the side of AMS. After that, they are going to conduct leak checks on a fourth and final repair work.
The 7.5-ton AMS, launched to the space in 2001, is developed by a 600-member multinational team. It features a thermal control system developed by Chinese scientists.
ISS crew members have conducted 223 spacewalks in support of assembly and maintenance of the orbiting laboratory.