When John Lane stood in his backyard and pointed his laser at the rain, he wasn’t thinking about weather on Earth. He was trying to figure out the best way to track lunar dust, part of a project to protect NASA’s Apollo landers from would-be moon visitors. But he ended up helping weather forecasters anyway, by finding a new way to measure the size of raindrops--something weather radar can’t do.
Lane, a physicist at Kennedy Space Center, was trying to calibrate a laser sensor that would pick up fine dust particles on the moon. The project is part of a NASA effort to protect its lunar heritage. New lunar landers, perhaps from the Google Lunar X Prize or other nations, would likely kick up dust and other material as they touch down on the moon. NASA wants to be sure its six Apollo sites are unperturbed, and understanding dust mechanics will help nail down how close new robotic landers could get.
“It's like sandblasting,” Lane explains in a NASA news release. “If you have something coming down like a rocket engine, and it lifts up this dust, there’s not air, so it just keeps going fast.” Some of this regolith (lunar soil) can even escape into orbit. It might even smack into the sensitive foil skins of the lunar descent modules, or maybe samples of waste left behind by astronauts. Impact by moon dust would ruin possible future experiments that would analyze what happened to some of that waste, so NASA wants to have some parameters for explaining the dust’s behavior.