HOUSTON - NASA astronaut Peggy Whitson, the first female commander of the International Space Station, returned to Earth at approximately 4:30 a.m. EDT Saturday, ending a mission during which she conducted five spacewalks and set a new record in American spaceflight.

Whitson and Russian cosmonaut Yuri Malenchenko, members of the 16th crew to live and work aboard the station, safely landed their Soyuz spacecraft in the steppes of Kazakhstan. Spaceflight participant So-yeon Yi also returned to Earth aboard the Soyuz. The landing was approximately 295 miles from the expected landing site, delaying the recovery forces' arrival to the spacecraft by approximately 45 minutes.

Whitson, 48, has accumulated more time in space than any U.S. astronaut in history. She and Malenchenko, who launched to the station on Oct. 10, 2007, spent 192 days in space. This was Whitson's second flight to the station. She served almost 185 days as a flight engineer on the Expedition 5 crew, which launched June 5, 2002, and returned to Earth Dec. 7, 2002. Whitson has totaled 377 days in space during two missions. On April 16, she surpassed the 374-day record set by astronaut Mike Foale during his six flights.

Malenchenko, 46, a Russian Air Force colonel, completed his third long-duration spaceflight. He spent 126 days aboard the Russian space station Mir in 1994, and commanded Expedition 7, spending 185 days in space in 2006. He also was a member of the STS-106 crew of shuttle Atlantis on a 12-day mission to the station in 2000. He has accumulated 515 days in space during his four flights. That is the ninth highest total of cumulative time.

The Expedition 16 crew worked with experiments across a wide variety of fields, including human life sciences, physical sciences and Earth observation. Many of the experiments are designed to gather information about the effects of long-duration spaceflight on the human body, which will help with planning future exploration missions to the moon and Mars.

The Expedition 16 crew members undocked their Soyuz spacecraft from the station at 1:06 a.m. The deorbit burn to slow the Soyuz and begin its descent toward the Earth began at 3:40 a.m.

Before undocking, Whitson and Malenchenko bid farewell to the new station crew, Expedition 17 Commander Sergei Volkov and Flight Engineers Oleg Kononenko and Garrett Reisman. Volkov and Konenko launched to the station April 8. They were accompanied by Yi who flew under a commercial contract with the Russian Federal Space Agency. Reisman came to the station aboard shuttle Endeavour on the STS-123 mission, which launched March 11.

For information about the International Space Station, visit:

http://www.nasa.gov/station

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