CAPE CANAVERAL, Fla. – NASA astronaut Scott Kelly blasted off in a Soyuz spacecraft from Kazakhstan on Friday afternoon to spend a year in space.
[SPACE HISTORY: Follow their journey | PICS: Rocket launches | VIDEO: Raw launch | WATCH: Docking at ISS]
Kelly and Russian cosmonaut Mikhail Kornienko embarked on a mission to the International Space Station.
Gennady Padalka will stay in space for six months.
The veteran space fliers are scheduled to reach their home for the next year — roughly 250 miles above Earth — in less than six hours.
By doubling that mission duration for two crew members for the first time on ISS — four cosmonauts lived for at least a year on Russia's Mir station — NASA and its partners hope to learn more about the issues astronauts might face on even longer voyages to Mars.
The space agencies are discussing assigning more astronauts to year-long missions.
It's something Kelly, a 51-year-old father of two daughters (ages 20 and 11) who spent nearly six months on the station ending in early 2011, was not enthusiastic about at first.
"I'll be honest with you, I wasn't all that interested," he said. "After mulling it over, talking to my family, friends, girlfriend, I decided that the challenges that staying in space for a whole year presented was appealing to me even considering the sacrifices."
Kornienko's wife cried upon learning about his second long spaceflight — this time for an entire year — but later supported the decision. The 54-year-old grandfather will fly with pictures of his family and his deceased parents.
"We have the chance to be the first to spend a whole year on the space station, and it will be of great use for future generations for science and for those who might fly further to Mars and to outer space," he said, through a translator.
Kelly does not conceal how difficult he expects living on the station for nearly a year — 342 days, to be precise — to be. But hopefully he'll experience nothing like the family crisis he confronted during his first expedition.
Halfway through that flight he learned about the shooting of his sister-in-law, then-U.S. Rep. Gabby Giffords, who is married to his twin brother, former astronaut Mark Kelly. Giffords continues to recover, but that day both Kellys endured early media reports that she had died.
Mark Kelly is in Central Asia to see his brother's launch.
Researchers will take advantage of a twin's involvement in the mission to study spaceflight's long-term effects. They'll compare how Scott responds over the year in microgravity to Mark, a four-time shuttle flier, back on the ground.
Months in space are known to cause loss of bone and muscle mass, weakened immune systems and impaired vision, but the upcoming mission will track those health impacts over more time, with better medical technology than was available during Russia's previous year-plus missions.
"That's one of the reasons why we're doing this flight and flying for longer than we have before, to better understand some of these effects and how to mitigate them for our future exploration goals," said Scott Kelly.
Based on experience and advice from cosmonauts who have flown longer — the longest single trip lasted 438 days — Kelly expects his biggest challenge will be pacing his workload to avoid burnout.
Appropriately, the mission patch for his Soyuz crew features marathon runners.
"I hope I get six months into this and I have six months of energy left in the battery to get to the end," he said. "I think I will."
On his last flight, however, he found he began feeling mentally ready to return home about two-thirds of the way through — after just four months, in that case. He hopes not to feel that way so soon this time.
It might help that Kelly will participate in a busy period involving what he calls the station's "reassembly." A module and other components will be rearranged, and he'll likely perform his first spacewalk.
During free time he plans to talk to family and friends with a Skype-like phone connection, see them in occasional video conferences, send emails, read books and watch TV shows uplinked to him, including Houston Texans football games.
"It hasn't escaped me that I'll watch a whole baseball season, which is very long, and a whole football season," he said.
He plans to maintain a daily journal to document his thoughts and feelings as the lengthy mission progresses, experiences he'll share with scientists.
In addition to Kornienko, Kelly will spend parts of his year in orbit with 13 others coming to and going from the outpost, including the three crew members there now. But he knows he'll miss the variety of people and weather on Earth, and will grapple with the monotony of being in the same place for so long.
"You'll miss your friends and family on Earth," he said. "You also miss being able to leave, being able to go outside your place of work. It's kind of like you're at work 24/7 for a whole year."
At the same time, he's looking forward to seeing how parts of the planet change over an entire year, its thin, fragile atmosphere, and visually stunning space weather phenomenon like the aurora.
By the end of the mission, Kelly's career total of 522 days in space will set a U.S. record, surpassing Mike Fincke's 382 days. But it will be Gennady Padalka, now 56 and launching with Kelly on his fifth spaceflight, who upon returning in six months will own the all-time record: 888 days, or more than two years of his life.
Reluctant initially, Kelly finally welcomed the opportunity to fly in space again, perhaps for the last time, in a different and more demanding way.
"I don't think I've ever done anything that will be as hard as this," he said. "I look forward to this flight and the challenge that the duration presents."