And now we have a tentative answer to the threat of an asteroid colliding, to cataclysmic effect, with our planet: NASA’s Double Asteroid Redirection Test, or DART. Developed by a team of scientists from the Johns Hopkins University Applied Physics Laboratory and NASA’s Planetary Defense Coordination Office, DART is an unmanned, remotely controlled astronomical suicide mission designed to nudge an asteroid that is half a mile in diameter out of its orbit. Doomsayers take note: This is only a test. The asteroid in question, Didymos — Greek for “twin,” and so named because it was discovered to be paired with its own small moon — is not actually on a collision course with Earth. Sometime between Thanksgiving week (perhaps as soon as the evening of Nov. 23) and February 2022, the team behind DART will launch it from Vandenberg Space Force Base in California on a SpaceX Falcon 9 rocket. The spacecraft will, if all goes according to plan, travel 6.8 million miles to reach and collide with Didymos’s moonlet, Dimorphos, which is 525 feet in diameter. DART will also ferry a shoebox-sized spacecraft contributed by the Italian Space Agency. Several days before DART’s impact with Dimorphos, that little craft, the LICIACube (Light Italian CubeSat for Imaging of Asteroids), will separate from DART to capture images of the impact.