CU Professor: Scott Kelly's Long Space Stay Will Help With Mars Mission Research

BOULDER, Colo. (CBS4) - He spent 340 days in space, but the toughest times may still be ahead for NASA astronaut Scott Kelly.

Kelly is heading home on Tuesday from a record breaking stay at the International Space Station. He's the first American to live in space for such a long period of time.

"Coming home is the more challenging part of this in some ways because now you come back to a gravity environment, your bones are weaker, more brittle potentially," said Dave Klaus, a professor of Aerospace Engineering at the University of Colorado Boulder.

Klaus told CBS4 Kelly's mission helps scientists understand how space effects the human body, using Kelly's twin brother and fellow astronaut Mark Kelly for comparison.

"That's a perfect ground control in a sense because it's a person who is essentially genetically identical," Klaus said.

The mission marks an important stepping stone.

"There's very much involved in all this exploration development that's all aimed at getting people to Mars," Klaus said.

It's a goal that NASA and the aerospace community hope Kelly's mission puts in closer reach.