A spacewalk was conducted today by astronauts Rex Walheim and Stan Love, members of the STS-122 Space Shuttle crew, to install the new Columbus module onto the International Space Station.

The spacewalk, or extra-vehicular activity (EVA), began at 14:13 UTC, with the astronauts leaving the Quest airlock of the Space Station, and starting work to install an attachment point on top of the Columbus module, to allow it to be moved by the Station's robotic arm. This was completed at 19:00, about an hour later than planned, owing to the installation taking longer than expected. Columbus was lifted out of the payload bay of Atlantis at 19:55 UTC, by the Space Station's robotic arm, Canadarm2. Astronaut Dan Tani, controlling Canadarm2 from aboard the ISS remarked "Columbus has started its trip to the new world". At 21:29, Columbus soft-docked with the Space Station's Harmony node, and the module finished bolting itself in place by 21:44.

Meanwhile, the astronauts performed some tasks to prepare for the next spacewalk, which is currently scheduled for Wednesday. They loosened bolts holding a nitrogen tank in place on the port truss segment of the Station, ahead of its replacement. It was originally planned that they would also disconnect pipes and electrical connections, however these objectives were delayed to Wednesday's spacewalk, due to time constraints. The EVA finished at 22:12 UTC, having lasted seven hours and fifty-eight minutes.

This marks the 102nd spacewalk as part of the International Space Station programme, and the first of three planned for the STS-122 Shuttle mission. It was originally planned that German astronaut Hans Schlegel would perform the EVA instead of Stan Love, however he was unable to do so due to an undisclosed medical problem.