Twin Brother Returns From Space With Something Very Different About Him

Growing up, Scott and Mark Kelly shared two very important things: nearly identical genes and a desire to boldly go where no one had gone before. But back then, they had no idea of what their future really held. In the years to come, they’d be the subjects of a history-making experiment in space. It would leave one brother permanently changed — and scientists everywhere scrambling for answers.

Scott and Mark Kelly

Yep, the two men both achieved their life-long dream of becoming astronauts. And this wasn’t only special for the pair, but also for NASA. It’s not every day you see a pair of twins who are both capable of space travel. NASA knew it had to take advantage of this.

Twin experiments

“Early on in our astronaut career, my brother and I had kind of wondered about it. ‘Hey, I wonder if they’ll ever do an experiment with the two of us, being genetically nearly identical,’” Scott explained to Space.com. And while it took a few years, NASA eventually approached the brothers with a proposition.

Worlds apart

With Mark as the “control” on Earth and Scott as the “experiment” on the International Space Station, the twins would spend almost a whole year on different worlds. This was meant to show the effects of space travel on the human body. But Scott had no idea just how much the trial would affect him.

Mark’s carefree life

Mark’s life on Earth didn’t change much, except for how little he saw of his twin brother. He ate whatever he wanted, drank whatever he wanted, traveled wherever he wanted, and did whatever he wanted. Life was not so carefree for Scott.