Pranay Mishra reached down to the floor of his workplace and scooped a handful of what might be the closest thing on Earth to the feel of Martian soil.

"This is actually unprocessed garnet," he said, sifting the gray granules in his palm. Tiny ruby-colored flecks caught the light. Mixed with diatomaceous earth, a fine powder of algae fossils often used by gardeners, the coarse gray stuff makes a decent substitute for the density and texture of Mars' dirt. The only difference is that on Mars, no one has to clean it up.

"I've torn up three pairs of shoes working in this," the JPL systems engineer said with a laugh. "It follows you home. It's in your car, it's in your house—it's everywhere."

At some point in the next several weeks, a critical amount of actual Mars dust will cover the solar panels of NASA's InSight lander, which has been studying the red planet's crust, mantle, core and seismic activity since 2018. The batteries won't generate enough voltage to keep the spacecraft's instruments online.