This is a story about dust. Dust that can mold into the shape of an astronaut’s boot and remain unchanged for millennia. Dust that cuts like glass. Dust so fine that it brings billion-dollar machines to their pneumatic knees.

Moondust.

For Jason Schuler, a robotics engineer at NASA’s Swamp Works, in Florida, it’s an obsession. He works on machines that can extract, pulverize, mold, analyze, and protect against extraterrestrial dirt. If future lunar explorers are to live off the land, they will need one of Schuler’s machines. Future moon missions could use lunar soil, or regolith, to make rocket fuel or to build useful structures. But that same regolith can also be a real annoyance. It can cause respiratory problems, cling persistently to almost any surface it touches, and render spacecraft unusable.

READ MORE Moondust Could Cloud Our Lunar Ambitions

The Trump administration has tasked NASA with sending humans to the lunar south pole by 2024. At the National Space Council meeting held in March, vice president Mike Pence explained that the agency’s long-term goal is to put humans on the moon for good. Assuming NASA can scrounge the billions of dollars it needs for a crewed lunar mission—and that’s a big if—the exploration wouldn’t stop there. The agency’s long-term plan is to take advantage of the weak lunar gravity to use the moon as a springboard to Mars. An added bonus is that water is believed to be embedded in the lunar regolith, which could, in theory, be broken down to make rocket fuel. But first, experts say several robotic missions will have to venture to the moon to learn about its makeup.

Swamp Works is one of the few places in the world with an enormous test bed that mimics the conditions on the lunar surface. Inspired by Lockheed Martin’s Skunk Works, the lab responsible for several major aviation breakthroughs, Swamp Works was designed to bring the same agile spirit to NASA. And it’s where Schuler and about a dozen other researchers are prototyping robots to explore and mine the moon. In particular, they’re testing the Regolith Advanced Surface Systems Operations Robot, or Rassor, a four-wheeled contraption about the size of a motorcycle but only a fraction of the weight.

Rassor can haul nearly 200 pounds of regolith at a time, which Schuler says is far more than any of the other lunar excavator concepts NASA is developing, given Rassor’s low mass and energy requirements. On the moon, the first mining machines will, of necessity, be very light, which makes digging all the more difficult. Conventional excavation techniques, which leverage Earth’s gravity, won’t work. That’s why Rassor has two saw-toothed cylindrical mining tools protruding from each end. By turning in opposite directions while digging, these counteracting forces allow the robot to get some traction in the moon’s low gravity environment.

Schuler can’t easily test its low-gravity performance, but he can see how the Rassor performs in a giant sand box filled with 120 tons of faux lunar regolith. The “Big Bin” is the world’s largest regolith test bed, and it is used by Swamp Works engineers to troubleshoot the bot before it heads to the actual lunar surface. Moondust is loose and incredibly fine, its particles jagged like broken glass. It’s also electrostatically charged, so it sticks to everything and is very difficult to remove. If machines don’t come up with a way to remove this dirt on their own, over time it will get caked to the body of the robots, rendering them immobile and their sensors useless.

Lunar regolith is quite unlike dirt on Earth, but there is at least one close analog on our home planet. A few years ago, a team of NASA researchers were on assignment at a basalt flow in Arizona as part of a Desert Research and Technology Study, which uses the high desert for mock moon and Mars missions. During one of the tests, Schuler says, an engineer climbed on a mound of dirt and sank up to his waist in the loose material. When his colleagues came to extract him, one of them, former Apollo astronaut Jack Schmitt, remarked how similar the material was to actual lunar regolith. “This is a guy who has been on the moon and is an actual geologist,” says Schuler. “There was nobody better qualified to evaluate this pile of dirt.” And sure enough, when a sample of the material was brought back for testing, the analysis showed that the dirt, which was waste from a nearby quarry, almost exactly matched the physical characteristics of lunar regolith.