Scott Kelly: Travel to Mars ‘Clearly Doable’

— -- After more than 300 days in constant micro-gravity, U.S. astronaut Scott Kelly is confident human travel to Mars is “clearly doable.”

“I think what we've done in space proves we can overcome challenges,” Commander Kelly told ABC News’ David Kerley from aboard the International Space Station. “It’s something that I hope to see in my lifetime,” Kelly commented about travel to Mars.

Kelly, who spent the last 11 months orbiting earth, is set to return home via Kazakhstan on March 1 after a consecutive 342 days in space. (With 520 interstellar days under his belt, he’ll hold the U.S. record for cumulative days in space as well.)

Spending so much time cooped up in a million-pound mobile laboratory cruising through the cosmos at 5 miles per second isn’t as effortless as it looks.

“Space is hard,” said Kelly. “You never leave, you can never go outside… it is very similar day after day for a really long time.”

When he lands, he’ll face a battery of tests that will help determine how the human body – and psychology – stands up to that much time outside earth’s atmosphere.

Scientists will examine his muscle mass, blood flow, bone density and body proteins: research that will inform plans for crewed missions to deep space and beyond.

“I absolutely feel great, but there are challenges, especially with radiation between the earth and Mars,” Kelly said.

They’ll run the same tests on twin brother, retired astronaut Mark Kelly, as part of NASA’s comparative “twin study.”

Before Scott’s launch, the brothers told Kerley that while Mark got the “easy part” of the assignment, Scott got “the fun part.” And though the monotony of space occasionally grated on his nerves, Scott still says he “wouldn’t trade places” with his twin “for anything.”

Of course, freeze dried food aside, there are some perks to the gig, including an incredible view.

From an array of breathtaking vistas (all chronicled on his twitter feed), Kelly says the northeastern side of the Himalayas were some of his favorites.

From space, the mountains “are incredibly remote looking and desolate, but at the same time beautiful, so I think if I had to choose one place I would go up in the foothills,” he said.

For now, he’s ready for some hearty filet mignon – and a meal “sitting at a table with friends and family.”

ABC News' Daniel Steinberger and Becky Perlow contributed to this report.