President George W. Bush recently set two goals for the nation’s space program: humans will return to the moon by 2020, and land on Mars by 2030. But human biology is not designed for space travel. The earth is, in effect, a spaceship, with an atmosphere, gravity and light cycles that allow us to thrive. Space, however, is inhospitable. To travel across vast distances of space, humans must bring along the conditions of spaceship earth. Researchers at the University of Virginia have begun looking for ways to help the human body adapt to months, perhaps years, of space travel during a Mars mission. Once astronauts leave Earth, there will be no day/night cycles. And on the Martian surface, the days are slightly longer than the 24-hour day on Earth, which likely will skew the natural rhythms of the astronauts’ biological clocks.