A NASA spacecraft is about to commit suicide. If everything goes as planned, it’ll ram into an asteroid on Monday afternoon. Astronomers will keep an eye on the asteroid to see how the impact affects its orbit around a larger companion asteroid. The mission is known as DART. It’s an early step in the effort to develop ways to protect Earth from asteroids or comets that might be on a collision course with our planet. An impacting spacecraft might deflect such a body just enough to miss us. The target is Dimorphos, which is about 525 feet in diameter. It orbits Didymos, which is about half a mile across. DART will hit the little moon head on. A small companion spacecraft will snap pictures from a safe distance. The system isn’t a threat to Earth. But it passes close enough that it’s easy to reach. And the sizes of the two bodies provide a good test of just what an impact can do. It should cause a small but measurable change in the orbit of Dimorphos. Astronomers will monitor the system f
