Last week on the podcast we talked about space health. Specifically, we told you about a new paper discussing the role that physicians will have to play in determining which citizens are fit enough for commercial jaunts into space.

Now let’s leap ahead, and much farther afield. What kinds of issues might a crew of astronauts face on a longer journey—say, a round-trip to Mars?

To find out, six volunteers spent a record 520 days confined to a simulated space habitat near Moscow. They emerged in 2011.

Now a report in the Proceedings of the National Academy of Sciences [Mathias Basner et al., Mars 520-d mission simulation reveals protracted crew hypokinesis and alterations of sleep duration and timing] shows that the simulated spaceflight did have real effects. Removed from natural light and the rhythms of everyday life, four crewmembers experienced some type of sleep disturbance. And one exhibited signs of chronic sleep deprivation in regular alertness tests. Overall, the crew also became more sedentary with time.

The researchers conclude that a real Mars mission would need to incorporate tactics such as timed light exposure or exercise to keep astronauts’ circadian rhythms on beat. Because it would be a bad idea to land on Mars sleepy and out of shape.

—John Matson

[The above text is a transcript of this podcast.]