International Space Station astronaut Ron Garan is seen with the Cupola of the ISS in the background in this image from NASA TV May 29, 2011. [Photo/Agencies]

Kelly and his crew also provided the space station with a platform full of spare parts and an extension boom for future repair work. The boom, installed Friday on the fourth spacewalk of the mission, marked the completion of the US portion of the space station.

The astronauts also worked on some of the critical life-support systems inside, in an effort to leave the orbiting outpost in the best possible shape for the shuttle-less years ahead.

Astronauts Mike Fincke and Gregory Chamitoff - who spent months living on the space station in years past - pretended they didn't want to leave Sunday morning. They were dragged into the shuttle by their crewmates. Garan joined in on the joke, waving goodbye as if he were heading out aboard Endeavour as well. He's just two months into his five-month station stay.

All told, the hatches between the two spacecraft were open 11 days.

Only one more shuttle flight remains for NASA.

Atlantis will blast off July 8 with a load of space station supplies to close out the 30-year shuttle program.

Kelly, meanwhile, will now have to go without daily calls to Giffords. He used the space station's Internet phone to keep abreast of her condition, and NASA even arranged a videoconference between the two.

Giffords was critically wounded January 8 in Tucson, Ariz., during a political event. She attended Kelly's launch May 16 and, two days later, underwent skull reconstruction.

She is not expected to be at Kennedy Space Center for Endeavour's homecoming given the inconvenient hour: 2:35 am.