NASA astronaut Scott Kelly, who returns next week after nearly a year aboard the International Space Station, said on Thursday the secret to enduring the longest U.S. spaceflight is marking individual milestones, not ticking days off the calendar.
Since arriving at the space station on March, 27, 2015, Kelly and Russian cosmonaut Mikhail Korneinko have served with eight different crewmates, unpacked six cargo ships, weathered two botched supply runs and participated in dozens of science experiments.
Kelly also made three spacewalks outside the $100 billion station, which flies about 250 miles (400 km) above Earth, and Kornienko made one.
"I've tried to do this with a deliberate pace, looking not really at the end, but at the next milestone," Kelly told reporters during his last inflight press conference.
"I could go another 100 days; I could go another year if I had to," he added.
Kelly and Kornienko's stint on the station, at about 340 days roughly twice as long as any previous U.S. mission, is intended to provide medical and engineering information to prepare for three-year missions to Mars.
Four Soviet-era cosmonauts flew longer missions aboard the now-defunct Mir space station. The longest flight was a 437-day mission between January 1994 and March 1995 by cosmonaut Valeri Polyakov, a physician.
"Physically, I feel pretty good," said Kelly, 52, a veteran of three previous spaceflights. "Even though I really look forward to going home, it's not like I'm climbing the walls."
Kelly's medical tests will continue for months after his return. His identical twin brother Mark Kelly, a former NASA astronaut, is participating in a series of related studies looking for genetic changes caused by the high radiation and weightless environment of space.
Scott Kelly, who previously spent 159 days on the station, said the hardest part of being in space for so long was being separated from his friends and family.
"The space station is a magical place," Kelly said, but added that even after a year, "it's just not normal."
"It is a harsh environment. For instance, having no running water, it's like I've been in the woods camping for a year," Kelly said.
After medical checks next week, Kelly said he will go to his Houston home to jump in his pool.
Kelly, Kornienko and cosmonaut Sergey Volkov are due to depart the station at 8:05 p.m. EST on Tuesday/0105 GMT and land in Kazakhstan 3-1/2 hours later.
Published 27 February 2016, 04:25 IST