Scott Kelly has had longer to look at the Earth from space than any other American astronaut and some of what he sees worries him. In a CNN interview, the astronaut, who is 322 days into a 342-day mission, says parts of the planet seem unwell. "There are definitely parts of Asia, Central America that when you look at them from space, you're always looking through a haze of pollution," he says. "As far as the atmosphere is concerned, and being able to see the surface, you know, I would say definitely those areas that I mentioned look kind of sick." From his vantage point, the atmosphere seems "very, very fragile and just kind of like this thin film, so it looks like something that we definitely need to take care of," he says.
Kelly is scheduled to return to Earth March 1 after a historic mission to study how long periods in space affect the human body. He says he has noticed changes in his vision, but "nothing alarming." His identical twin, retired astronaut Mark Kelly, has been Earthbound while his brother was on the International Space Station, giving scientists the perfect opportunity to track the changes caused by such a long time in zero gravity. Kelly says that despite the challenges, he believes a Mars mission is possible with public support and financial support from governments, "because I think, technically, pretty much anything we have ever put our mind to we have been able to accomplish." Click for the full interview. (Read more Scott Kelly stories.)