Send Astronauts to Mars —and Leave Them There

The most feasible way to get humans on Mars is to offer retirement-age astronauts one-way tickets to live out their last days on the red planet. Say what? It's not as crazy as it sounds, writes scientist Lawrence Krauss in the New York Times, who believes his plan would solve the major hurdles of a space mission to Mars.

For starters, cost. The trip would be far less expensive without requiring fuel—and thus a bigger ship—for a return trip. Also, the journey would likely subject astronauts to a life-shortening dose of radiation. Thus, a one-way space shuttle for 65-plus astronauts. Krauss thinks there'd be plenty of takers, and "human space travel is so expensive and so dangerous that we are going to need novel, even extreme solutions if we really want to expand the range of human civilization beyond our own planet." (More Mars stories.)