NASA has a new Vision for Space Exploration: in the decades ahead, humans will land on Mars and explore the red planet. Brief visits will lead to longer stays and, maybe one day, to colonies.

First, though, we’re returning to the Moon.

Why the Moon before Mars?

“The Moon is a natural first step,” explains Philip Metzger, a physicist at NASA Kennedy Space Center. “It’s nearby. We can practice living, working and doing science there before taking longer and riskier trips to Mars.”

The Moon and Mars have a lot in common. The Moon has only one-sixth Earth’s gravity; Mars has one-third. The Moon has no atmosphere; the Martian atmosphere is highly rarefied. The Moon can get very cold, as low as -240o C in shadows; Mars varies between -20o and -100o C.

Even more important, both planets are covered with silt-fine dust, called “regolith.” The Moon’s regolith was created by the ceaseless bombardment of micrometeorites, cosmic rays and particles of solar wind breaking down rocks for billions of years. Martian regolith resulted from the impacts of more massive meteorites and even asteroids, plus ages of daily erosion from water and wind. There are places on both worlds where the regolith is 10+ meters deep.

Operating mechanical equipment in the presence of so much dust is a formidable challenge. Just last month, Metzger co-chaired a meeting on the topic: “Granular Materials in Lunar and Martian Exploration,” held at the Kennedy Space Center. Participants grappled with issues ranging from basic transportation (“What kind of tires does a Mars buggy need?”) to mining (“How deep can you dig before the hole collapses?”) to dust storms–both natural and artificial (“How much dust will a landing rocket kick up?”).

More here.