Which leads us neatly onto the Rutherford Appleton Laboratory in the UK, which has devised a "mini magnetosphere" that essentially recreates the protection provided by the Earth's magnetic field. The scientists have so far used the magnetosphere to protect a scale spacecraft from radiation, and they're now working on a concept spacecraft, called Discovery, with a full-scale magnetosphere that could theoretically take humans to Mars.

"We have found a habitable environment," said John Grotzinger, project scientist for the Curiosity mission. "The water that was here was so benign and supportive of life that if a human had been on the planet back then, they could drink it."