The shuttle undocked as the two craft soared more than 200 miles above the Atlantic, just west of Africa's Western Sahara. The two crews spent 10 days together, working to install a new room, called Tranquility, and a domed observation deck the likes of which had never been seen before in orbit.
The compartments represented the last of the space station's major building blocks.
Mission Control told the six shuttle astronauts that they've had "an absolutely awesome mission," but now it's time to say "goodbye station, hello, Earth!" Touchdown is set for late Sunday night in Florida.
"It's been good having you. Sorry to see you guys leave," space station resident Timothy "TJ" Creamer called out as Endeavour backed away.
"We're sorry to go," replied shuttle commander George Zamka. "Hope you get to enjoy Tranquility and the new view."
The seven windows in the space station's new lookout were shuttered before Endeavour's departure, to protect against thruster contamination. The shuttle astronauts took one last long look out those windows late Thursday before retreating back into their ship to prepare for the undocking.
Endeavour then took a slow lap around the orbiting complex for picture-taking.
"Godspeed guys," radioed the space station's skipper, Jeffrey Williams.
Early Saturday, the shuttle astronauts were going to pull out their long laser-tipped boom to inspect their ship for any signs of micrometeorite damage that might jeopardize Sunday night's re-entry.
Thanks to Endeavour and its crew, the space station is now 98 percent complete, with a mass of 800,000 pounds. The two new compartments
- worth more than $400 million - were supplied by the European Space Agency.
