The space station crew beamed down video of the departing shuttle, the last ever shot of Endeavour in orbit. It was a dark, solitary image against the blue, cloud-covered Earth and grew increasingly smaller.
NASA's youngest shuttle -- the baby of the fleet with just 25 space voyages -- is due back in Florida early Wednesday. Its next stop after that will be a museum in Los Angeles for what some consider to be an early retirement.
Endeavour undocked close to midnight Sunday, ending 11 1/2 days of joint flight. The two spacecraft were soaring more than 200 miles above Bolivia when they parted.
By the time they were over eastern Europe, the shuttle astronauts could see the $2 billion cosmic ray detector they installed on the space station, as well as the new platform holding spare parts.
"We're the ones that get to see this incredible view, but you're all with us in spirit, and this is really a new day for science aboard the space station," shuttle commander Mark Kelly told Mission Control.
Endeavour and its crew left behind a space station that now has a mass of 905,000 pounds and is 100 percent complete, at least as far as NASA's share of the 12-year project. On the fourth and final spacewalk of the mission Friday, the astronauts attached an extension pole and declared the construction effort over.
The Russian Space Agency still intends to add another compartment or two. But the other partners have all the major items they need already up there for the decade ahead.
Atlantis will make one last supply run to the space station this summer to close out the 30-year shuttle program.
Endeavour's final job in orbit was to provide a platform for a navigation experiment, designed to assist future spacecraft that may fly to an asteroid or Mars one day. The shuttle hung around a few extra hours to accomplish the task.
"We're closing another chapter on the flight," astronaut Andrew Feustel radioed when the experiment ended. He asked if flight controllers got enough data. "We've got a roomful of happy people down here," replied Mission Control.
The lead shuttle flight director, Gary Horlacher, praised Kelly and his crew for their "absolutely flawless" 16-day mission. He wished them "a safe voyage" and said he'd meet them on the runway at Kennedy Space Center.
Kelly promised to see him there, although he noted that stiff crosswind might postpone the touchdown.
Endeavour will aim for a rare middle-of-the-night touchdown. Landing time is 2:35 a.m. Wednesday.
Just four hours beforehand, Atlantis will begin the three-mile trek from the hangar to the launch pad one last time. Hundreds if not thousands of Kennedy Space Center employees will be on hand for the double-header events.
Built to replace the lost Challenger, Endeavour will have racked up 123 million miles by flight's end, beginning with its first journey in 1992, and have circled Earth more than 4,670 times. NASA's launch director has mentioned on more than one occasion that Endeavour still looks new.
One person missing the landing will be Arizona congresswoman Gabrielle Giffords, the wife of Endeavour's commander. She attended the May 16 launch, but underwent skull reconstruction two days later in Houston. She's recuperating but Kelly said the landing will occur at an inconvenient hour and the nighttime views will be limited.
Kelly got a special musical send-off Sunday from Giffords.
The wakeup call was a song by a Tucson, Ariz., band. Kelly said the song, "Slowness" by Calexico, is about two people reaching across a distance, and references places in Tucson, his wife's hometown.
"I know she really, really wants to get back there," Kelly said. "It's an appropriate song because that's coming soon."