No asteroid is known to pose a significant threat to Earth within the next century... but just in case one ever does, we're getting ready. NASA's DART mission is our first planetary defense test of "kinetic impactor" technology—in other words, we're crashing a spacecraft into a small asteroid (named Dimorphos) to change its course. Though DART's impact will be small (and won't bring Dimorphos near Earth), the data we collect will help us prepare if a large Earth-bound asteroid or comet is ever d