If you've ever endured an 8+ hour flight, you know how good if feels to get off the plane and breathe fresh air. Now imagine a 520-day flight.
Scott Kelly
has just returned from more than a year in space, the longest of anyone ever. He celebrated 2 birthdays on the International Space Station and came back 2 inches taller than when he left.
Kind of puts sports and pop stars' accomplishments in perspective, doesn't it?
Being an identical twin, researchers for the first time have a control subject in his brother that allows them to accurately determine the physiological effects of living in space, essential data if we're going to send humans to Mars as planned.