BAIKONUR, Kazakhstan (AP) - American astronaut Scott Kelly and Russian counterpart Mikhail Kornienko blast off early Saturday to begin a year away from Earth.
The trip is NASA's first stab at a one-year spaceflight, anticipating Mars expeditions that would last two to three years. Their Soyuz space capsule sets off from Russia's manned space launch facility on the steppes of Kazakhstan and docks with the space station several hours later.
Gennady Padalka of Russia also is to be aboard the Soyuz capsule; he is scheduled for the standard six-month tour of duty aboard the International Space Station.
Kelly's identical twin Mark, a retired astronaut, agreed to take part in many of the same medical experiments as his orbiting sibling to help scientists see how a body in space compares with its genetic double on Earth.
Kelly and Kornienko will remain on board until next March. During that time, they will undergo extensive medical experiments, and prepare the station for the anticipated 2017 arrival of new U.S. commercial crew capsules. That means a series of spacewalks for Kelly. They also will oversee the comings and goings of numerous cargo ships, as well as other Russian-launched crews.
Doctors are eager to learn what happens to Kelly and Kornienko once they surpass the usual six-month stay for space station residents. Bones and muscles weaken in weightlessness, as does the immune system. Body fluids also shift into the head when gravity is absent, putting pressure on the brain and the eyes, impairing vision for some astronauts in space.
The year-long stint will allow doctors to assess whether such conditions are aggravated by a long spell in space or whether they reach a point of stasis or even taper off.
NASA has never flown anyone longer than seven consecutive months. The Russians hold the world record of 14 months, set by a physician-cosmonaut aboard the former Mir space station in 1994-1995. Several other Russians spent between eight and 12 months at Mir. All but one of those long-timers are still alive.
Heintz reported from Moscow.
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