Four Atlantis astronauts are in their final hour or so aboard the International Space Station before becoming the last shuttle crew to exit station hatches.
The crew is scheduled to join the station's six-person Expedition 28 crew at 9:19 a.m. for a farewell ceremony before they separate and close hatches between the spacecraft.
Watch the ceremony live here by clicking the NASA TV box at right.
Flying the 135th and final shuttle mission, Atlantis launched July 8 and arrived at the station July 10.
During eight days of work aboard the outpost, the shuttle crew transferred a year's worth of cargo to the station, packed more than 5,600 pounds of gear for return to Earth, and assisted a spacewalk that retrieved a failed station coolant pump.
A few final items are now being stowed on Atlantis' middeck.
Atlantis is scheduled to undock early Tuesday to begin the trip home to a planned Thursday morning landing.
Earlier today, the crew successfully moved the Raffaello cargo module from the station back into Atlantis' payload bay.