Mission's End: ISS Astronauts to Return to Earth

Threeastronauts will cast off from the International Space Station (ISS) Saturday toride a Russian spacecraft back to Earth and end their orbital mission.

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"It's beenan extraordinary privilege for us to represent humankind as, for a period oftime, the only two human beings living off the surface of the Earth," saidMcArthur, commander of Expedition 12, during a brief change of command ceremonyFriday. "But all wonderful experiences have an end."

Changing of the guard

McArthurand Tokarev, Expedition 12's flight engineer, are leaving the ISS in control ofExpedition13 commander Pavel Vinogradov, of Russia's Federal Space Agency, with NASAscience officer Jeffrey Williams serving as the increments flight engineer. TheExpedition 12 crew arrived at the ISS in October2005.

"We willcontinue our mission, our work, in space," Vinogradov said during the ceremony.

McArthur,Tokarev and Pontes are expected to land their Soyuz TMA-7 spacecraft on thesteppes of Kazakhstan in Central Asia at about 7:48 p.m. (2348 GMT).

While theExpedition 12 crew is wrapping up a six-month mission aboard the ISS, Pontes iscompleting a 10-day spaceflight, eight of which were spent conductingexperiments at the station. His spaceflight marks Brazil'sfirst foray into human spaceflight.

"EverythingI encountered here was equal to or better than I expected," Pontes said Friday."Thanks to Bill and Valery for an excellent six months of service."

Set for landing

Pontes andthe Expedition 12 crew are scheduled to seal themselves inside their Soyuzspacecraft at about 1:30 p.m. EDT (1730 GMT) and, three hours later, undockfrom their berth at the aft end of the space station's Zvezda service module.

Tokarevwill command Soyuz trip back to Earth, an hour-long descent that will begin atabout 6:58 p.m. EDT (2058 GMT) when the TMA-7 vehicle fires its engines toleave orbit.

Thespacecraft's gumdrop-shaped crew compartment will separate from its orbital andengine modules, plunge through the atmosphere heat shield first, and thendeploy parachutes about 15 minutes prior to landing, NASA officials said. A setof retrorockets will fire to further slow the capsule's descent just beforelanding.

A fleet ofhelicopters, recovery crews and medical personnel are staging in Kustanai,Kazakhstan to meet the Pontes and the Expedition 12 crew once they land, NASAofficials said.

DuringFriday's command-change ceremony,  Williams presented McArthur - a retiredU.S. Army colonel, aviator and four-time spaceflyer - with the Army AviationAssociation of America's (Quad-A) Order of St. Michael's Gold Award to honorthe more than 30 years of service the veteran astronaut has committed to thearmed forces.

"I'm almostat a loss for words here," said McArthur, who also earlier spoke to top U.S.Army officers with Williams. "We are truly proud to be soldiers in space."

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