NASA astronauts Sunita "Suni" Williams and Barry "Butch" Wilmore have been on the International Space Station since June, even though they initially expected to stay for just eight days. They'll be back on Earth in late March.

NASA astronaut Sunita Williams and Butch Wilmore on Thursday stepped out of the International Space Station (ISS) for 5.5-hour spacewalk, setting a new record, the US space agency said.

Commander Sunita Williams and Butch Wilmore floated out to perform maintenance work and wipe the International Space Station’s exterior for evidence of any microbes that may still be alive after launching from Earth and escaping through vents.