NASA astronaut Scott Kelly has returned to earth this week after spending 340 days in space. It was almost a year for all of us, but the record-breaking astronaut says it was like ‘forever’ in microgravity.

It was a very long trip to stay in microgravity, says Kelly. In a statement at NASA news conference on Friday, the 52-year old astronaut admits that one year at the International Space Station (ISS) was a long time. It was a way longer than thought, as per Kelly.

The ISS is a habitable artificial satellite hovering about 400 kilometers over earth. It completes 15.54 orbits per day. During his stay of over 340 days aboard the space station, Kelly travelled about 144 million miles. He said that those were the happy moments when a Soyuz capsule carrying him and two other astronauts landed on the surface of earth. That time was better than his return a few years ago from a 159-day mission to the ISS, he added.

According to the astronaut, his skin is feeling very sensitive after the space visit. It is almost like a burning feeling, Kelly said.

Now, Kelly and Russian cosmonaut Mikhail Kornienko, who also stayed at the ISS for almost one year, will undergo some tests, results of which will define how human body behaves during long space missions. Scientists hope it may help plan future deep space missions.

“By looking at Mark’s results collected over the course of the year, we can see what the normal variations might be. Where genetic changes were faster in Scott Kelly, those will tell us what areas to investigate in the future”, said John Charles, an associate manager for NASA’s human research program.