From the number of daily sunrises to preparing a cup of coffee , living in microgravity about 250 miles above the Earth is remarkably different from terrestrial life.

Scott Kelly , who recently wrapped up a 340-day mission aboard the International Space Station, is among the rare few who understands this well.

"I've been up here for a really long time and sometimes, when I think about it, I feel like I've lived my whole life up here," Kelly told CNN on Tuesday.