How the Mars500 volunteers fared during their simulated journey to the Red Planet

In the movie "Alien," astronauts like Ripley traveled through space in deep sleep chambers. But in real life, there's no short cut for traveling to distant planets.

To find out what that kind of trip would be like, six men volunteered to step into tight quarters, lock the doors and spend more than 500 days pretending to fly to Mars. Scientists tracked their every move, from sleep patterns to exercise habits.

Now the results of that study are now being published by the journal Proceedings of the National Academy of Sciences. David Dinges, who co-authored a paper on the experiment, joins the show to tell us about how the six brave "guinea pigs" fared in the experiment.