Space station trio set to return to earth Tuesday

CAPE CANAVERAL, Fla. -- Three of six crew members living aboard the International Space Station are poised to undock and return to earth on Tuesday after 168 days in space.

Outgoing Expedition 36 space station commander Pavel Vinogradov handed over command of the orbiting outpost to fellow cosmonaut Fyodor Yurchikhin on Monday in preparation for his crew's planned departure.

Russians Vinogradov and Alexander Misurkin and American Chris Cassidy, who arrived aboard the space station on March 28, are due to board their Soyuz TMA-08M craft at about 4:00 p.m. EDT on Tuesday in preparation for the craft's hatch closure at 4:20 p.m.

They will leave behind Yurchikhin, NASA astronaut Karen Nyberg and Italian astronaut Luca Parmitano who will stay aboard the space station until their departure in November.

Cassidy, along with Luca, performed two spacewalks during his stay to prepare the orbiting outpost for an upcoming Russian research module this December.

Based on the Russian timeline, the Soyuz spacecraft will undock from the Poisk docking port at 7:35 p.m., and slowly back straight out to a distance a few hundred feet out before circling around the station and departing.