Two astronauts have ventured out on the last spacewalk of the space shuttle era.
In a departure from previous shuttle visits, the job fell to space station crew Michael Fossum and Ronald Garan. The four-person Atlantis crew is the smallest in decades, and so the lone spacewalk of the mission was handed over to the full-time station residents.
It was the 160th spacewalk in the 12 1/2-year life of the orbiting outpost, and the last one planned for Americans for nearly a year.
The pair paused to admire the view as the linked craft soared above the Kennedy Space Centre, from which Atlantis departed last Friday on the very last shuttle flight.
Then Fossum and Garan headed to a storage platform to repair an ammonia coolant pump that stopped working last July and, for more than two weeks, left the space station with only half its cooling capability.
Nasa wants the pump brought back to Earth aboard Atlantis so engineers can work out why it stopped working to help them keep the on-board station pumps running. The space station is intended to operate until at least 2020.
While the spacewalk unfolded, the majority of the eight astronauts inside worked to unload the nearly five tons of supplies that were delivered in a giant cargo carrier by Atlantis. It represents a year's worth of food, clothes and other housekeeping items, to tide the crew over in case commercial rocket makers fall behind in their own cargo runs. The first such haul is supposed to take place by year's end.
Until now, the shuttle has hoisted the bulk of supplies to the space station. Cargo runs by Russia, Japan and Europe will continue.
Nasa is turning to private enterprise in the post-shuttle period, so it can meet the White House goal of sending astronauts to an asteroid by 2025 and Mars the decade after that.
The 13-day flight by Atlantis is the last for the 30-year shuttle program. Atlantis is due to return on July 21 to Kennedy, where it will go on display at a tourist centre.