After closing the hatch on Sunday, shuttle pilot Alan Poindexter gently unlocked latches and released powerful springs that pushed the spacecraft away from station.

"Alpha, Houston, physical separation confirmed," radioed to mission control in Houston, Texas, shuttle commander StephenFrick.

Once at a safe distance, Atlantis will fire up its engine and execute a fly-around the ISS so that its protective tiles can be photographed and inspected for possible damage one more time before its return to Earth.

The procedure was introduced in the wake of the 2003 fiery demise of the US shuttle Columbia, which burned upon re-entry into the atmosphere because of damaged shielding.

Hitching a ride home aboard Atlantis is American Daniel Tani, a master spacewalker and operator of robotic arms, who is returning to Earth after working on the ISS since October.

But the spaceship has left behind Frenchman LeopoldEyharts,amedical researcher and engineer from France's National Centerof Space Studies.

He earned his stripes 10 years ago, working for more than 20 days aboard the now-defunct Russian SpaceStation Mir. Eyharts performedexperimentsintheareasofmedicalresearch, neuroscience,biology,fluidphysicsandtechnology.

The Frenchman will stay aboard the station until March, getting the newly installed European-made Columbus laboratory -- a new facility delivered into orbit by Atlantis -- up to speed.

"We are incredibly excited to see it right on our left over there -- with the lights on and ready for action," shuttle commander Stephen Frick told reporters in a final briefing before departure.

The French astronaut paid tribute to Tani, calling him "a great guy."

"I have been really impressed by the experience he acquired here at the space station," said Eyharts. "It was really a pleasure and honor to receive a handover from him."

Attached to the station on February 11, ColumbusisEurope'slargestcontributiontotheorbiting complex that up to now had been largely a preserve for Americans and Russians.

Twenty-threefeet (seven-meter)long and15feet (4.5 meters)indiameter,themodulewillhouseexperimentsinlifesciences,materialsscience,fluidphysicsandotherdisciplines, adding the station's mission a new dimension and a more international profile, said US space officials.

During Atlantis's stay at the station, astronauts conducted three spacewalks to attach Columbus to the ISS and prepare it for scientific work. They also replaced an expended nitrogen tank on a key truss aboard the complex.

Reflecting on the past and future of the station, Tani said it represented a vivid example of how international relations had switched from confrontation to cooperation since World War II and the Cold War.

"I have spent time with men from France, from Italy, and from Germany, and from Russia," said the departing astronaut. "Nations that had not always been friendly are now cooperating, and we are doing great things."

If everything goes as planned, Atlantis will land at the Kennedy Space Center in Florida on Wednesday.

The return of the Atlantis is anxiously awaited by the US Navy, which plans to shoot down a disabled spy satellite that is threatening to plunge into Earth's atmosphere sometime in late February or early March.

The navy has modified three SM-3 missiles aboard Aegis ships, defense officials said. It wants to intercept the satellite at a point just above the atmosphere to increase the likelihood of bringing it down in an unpopulated area.

But the military has given assurances that no missiles will be fired until after the Atlantis mission ends.

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