ZHEZKAZGAN, Kazakhstan, March 2 (UPI) -- NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko returned to Earth after spending nearly a year in space on the International Space Station.
The Soyuz TMA-18M spacecraft capsule carrying Kelly, Kornienko and Russian crew member Sergey Volkov landed in Kazakhstan at 10:26 a.m. Wednesday, or 11:26 p.m. ET Tuesday. Kelly and Kornienko's 340-day stay in the ISS is about twice the length of a normal deployment and was part of a study to determine the effects of long-term spaceflight on the human body.
Volkov arrived at the ISS on Sept. 4.
"Scott Kelly's one-year mission aboard the International Space Station has helped to advance deep space exploration and America's Journey to Mars," NASA Administrator Charles Bolden said in a statement. "Scott has become the first American astronaut to spend a year in space, and in so doing, helped us take one giant leap toward putting boots on Mars."
Overall, Kelly has spent a total 520 days in space over four flights. Kornienko has spent 516 days in space across two flights and Volkov has spent 548 days on three flights.
"Kelly and Kornienko specifically participated in a number of studies to inform NASA's Journey to Mars, including research into how the human body adjusts to weightlessness, isolation, radiation and the stress of long-duration spaceflight. Kelly's identical twin brother, former NASA astronaut Mark Kelly, participated in parallel twin studies on Earth to help scientists compare the effects of space on the body and mind down to the cellular level," NASA said in a statement.
Kelly frequently posted to social media during his stay in space, posting images of his final sunrise aboard the ISS on Tuesday.