NASA’s DART mission will test a planetary defense strategy by hitting an asteroid

Hopefully, a spacecraft launched by NASA last November will crash into an asteroid on Monday.

If everything goes absolutely perfectlythat impact will push the asteroid into a slightly different orbit, meaning that for the first time humans will have changed the trajectory of a celestial object.

Making history, however, is accidental. The real mission is to defend the planet.

There is no need to panic: the target space rock has no chance of hitting Earth, nor any other known asteroid for at least half a century. This NASA mission, run by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, is testing a technique to redirect an asteroid in case the future people of Earth really need to take out one in the way.

The basic idea couldn’t be simpler – hit it with a hammer! But the degree of difficulty is high, in part because no one has ever seen the asteroid that NASA intends to push. It is a moon named Dimorphos which is the size of a football stadium.

Sky observers using the world’s most powerful telescopes detect the moon only as a shadow crossing the largest asteroid it orbits, Didymos, as the two surround the sun together. The pair forms a “double asteroid”, a common arrangement in our solar system.

Here’s how the $ 330 million Double Asteroid Redirection Test (DART) works: