The space shuttle Atlantis has left the international space station after a week-long construction project.
Atlantis pulled away from the station very slowly, with its jet thrusters turned off to avoid contaminating the outpost with exhaust.
During their week-long visit, shuttle astronauts successfully completed their main construction task, lengthening the station's backbone.
They mounted a 15-meter aluminum girder, the second of 11 that will eventually span 100 meters to hold air conditioning, power, and data relay equipment for future research laboratories.
The effort required three spacewalks by two astronauts to connect kilometers of wires, optical fibers and tubes carrying coolant through three large heat radiators.
A similar section is to be installed during the next shuttle visit scheduled for November, a mission that will also bring a fresh crew to the station.
Atlantis is to return to Earth on Friday.