Year in Space: Record-long US spaceflight leaves astronaut Scott Kelly feeling soreCAPE CANAVERAL, Mar 6(AZINS) Astronaut Scott Kelly said on Friday he returned from a record-long US spaceflight with sore muscles, joint pain, over-sensitive skin and a sense he had been away for more than a year.

"It seemed like I lived there forever," Kelly told reporters at the Johnson Space Centre in Houston and on a conference call during his first news conference since returning from a 340-day mission aboard the International Space Station (ISS).

Kelly's mission, which was about twice as long as astronauts typically serve aboard the station, was part of a pathfinder program to prepare for missions to Mars that will last more than two years. Kelly, a veteran of three previous spaceflights, said he initially felt well after landing in Kazakhstan on Tuesday, but then fatigue and muscle soreness quickly set in.

"I'm kind of surprised how I do feel different physically than the last time, with regards to muscle soreness and joint pain. That was something that was kind of unexpected," Kelly said. The 52-year-old astronaut added that he is wrestling with over-sensitive skin, which leaves him with a slight burning sensation.

Kelly and his crewmates tackled more than 450 experiments during the flight, which eclipsed the previous longest US spaceflight of 215 days. Four Soviet-era cosmonauts lived in orbit even longer aboard the now-defunct Mir space station, including a mission lasting nearly 438 days that ended in March 1995.

Kelly said it was hard being away from family and friends, but that he could have stayed longer. "Whether it's science or going to a certain destination, I think people rise to the occasion if you're doing something important," Kelly said. "If going to Mars takes two years or two-and-a-half years, that's doable."

Like many space travelers, Kelly returned to Earth with an increased appreciation of the planet and sense of its fragility. "You can see a lot of pollution over parts of Asia that is almost continuous. You can't really see the ground very well. And those fires in California over the summer, that smoke was pretty extensive. But the predominant thing is you just notice how thin the atmosphere is, how fragile it looks. That combined with these large swabs of pollution is somewhat alarming," Kelly said.

Kelly will continue to undergo a battery of medical, psychological and other tests for about a year so scientists can learn more about how spaceflight impacts the human body and mind. His identical twin brother, former astronaut Mark Kelly, also is participating in studies looking at possible genetic changes from spaceflight, which may impact cancer research, said John Charles, who oversees NASA's human research program. "I am confident in saying that it will influence how we understand cancer," Charles he said.

Kelly and his twin were reunited on Wednesday. By then, the 1.5 inch (3.8 cm) increase in height he experienced as a result of his spine expanding in microgravity had

reversed. "He's squished back to normal height," Mark Kelly told reporters.