Updated 7:18 p.m.: Capsule with American and Russian aboard docks with space station
The capsule carrying a Russian and an American who are to spend a year away from Earth docked Saturday with the International Space Station.
Mikhail Kornienko and Scott Kelly are to spend 342 days aboard the orbiting laboratory, about twice as long as a standard mission on the station. The Soyuz space capsule, also carrying Russia's Gennady Padalka for a six-month stay, docked about six hours after launching from Russia's manned space facility in Kazakhstan.
Once the hatches are opened between the two craft after a long procedure, the three will enter the space station to join American Terry Virts, Anton Shkaplerov of Russia and Italian Samantha Cristoforetti, who have been aboard since late November.
The trip is NASA's first attempt at a one-year spaceflight; four Russians have spent a year or more in space, all on the Soviet-built Mir space station.
Updated 1:04 p.m.: NASA astronaut blasts off for 1-year trip on space station
American astronaut Scott Kelly and his Russian counterpart Mikhail Kornienko blasted off early Saturday on a mission to spend an entire year away from the Earth.
The trip is NASA's first attempt at a one-year spaceflight, anticipating Mars expeditions that would last two to three years.
Their Soyuz space capsule set off from Russia's manned space launch facility on the steppes of Kazakhstan at 1:42 a.m. (1942 GMT Friday; 4:42 p.m. EDT Friday) and was to dock with the International Space Station about six hours later after making four orbits of the planet.
NASA is carrying a live stream with updates and replays of the launch and other material:
Cosmonaut Gennady Padalka of Russia was also aboard their Soyuz capsule. He is scheduled for the standard six-month tour of duty aboard the 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. They are 51.
Kelly and Kornienko, 54, 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, which will be his first.
The two men also will oversee the comings and goings of numerous cargo ships, as well as other Russian-launched space crews and an expected September visit from singer Sarah Brightman on a "space tourist" trip.
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 yearlong 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 in space, set by Valery Polyakov aboard the former Mir space station in 1994-95. Several other Russians spent between eight and 12 months at Mir. All but one of those long-timers are still alive.
A year in space will carry not only physical challenges, but emotional ones as well.
A day before the launch, Kornienko said he would long for the sights of nature. Even on his mission in 2010, which was half as long, he said he had asked to be sent a calendar with photos of rivers and woods.
Kelly said he thought one of the biggest challenges would be to pace himself mentally so he could remain energetic during the year aboard the laboratory.
But he joked that he wouldn't miss his sibling.
"I've gone longer without seeing him, and it was great," he said.
— Dmitry Lovetsky and Jim Heintz/Associated Press
Heintz reported from Moscow.
8:31 a.m.: NASA astronaut Scott Kelly set to begin year in space
Later today, a Russian rocket is scheduled to carry a Russian cosmonaut and an American astronaut to the International Space Station, where they will live for a full year, twice as long as people usually stay.
No American has lived in space for longer than 215 days. Only a few people have ever gone on space trips lasting a year or more — the longest was 437 days — and they're all Russian cosmonauts. The last year-plus stay in space occurred nearly two decades ago.
What's more, NASA's upcoming mission offers scientists a unique opportunity to study the effect of spaceflight on the human body. That's because the astronaut making the trip, Scott Kelly, has an identical twin brother, Mark Kelly, who's a retired NASA astronaut.
Initially, NASA did not plan to compare the earthbound twin with the one on the long-duration space mission. But after Scott Kelly got this assignment, he went to a briefing to get ready for a press conference.
"And I asked the question, 'Hey if someone just asks...will there be any comparative studies between you and your brother, how should I answer that?'" recalls Scott Kelly in a NASA video.
A few weeks later, he explained, a program scientist came back to him and said, "It actually looks like this might be something that the science community is interested in."
Over the next year, researchers will scrutinize Scott and Mark Kelly in what NASA is calling the Twins Study. Ten separate investigations will look at space travel's effect on everything from gut bacteria to eyesight.
Christopher Mason, a geneticist at Weill Cornell Medical College in New York City, will be searching for changes in gene activity. "The advantage of this study is that we will get a complete profile, I would even argue the most comprehensive molecular profile of a human being that's maybe ever been generated," says Mason. "And then, to boot, we'll get the comparison of someone on Earth who's the identical twin."
His colleague Francine Garrett-Bakelman has already been collecting blood from the twins, and she'll periodically get more samples from Scott that are returned to Earth. Scientists can't draw any definitive conclusions from just one set of twins, she notes, "but you can get some idea of what things might change over time, between space and Earth."
That's something NASA needs to know as it contemplates attempting longer spaceflights to places like Mars.
This will be Scott Kelly's fourth space trip. He did two shuttle missions and also lived on the station for about five months. While there, he sent back a video tour of his cramped crew quarters, where he seemed pretty comfortable. "I sleep much better up here than I do in my own bed at home," he said, demonstrating how he zips himself into a sleeping bag hanging from the wall.
But recently, he's said that there are some things on Earth he expects to miss during his year in space — like his children's birthdays, good food and the rain.
— Nell Greenfieldboyce/NPR
This story has been updated.