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

A NASA spacecraft that hurled itself into an asteroid two weeks ago changed the space rock’s orbit as scientists had hoped it would, the mission team announced today from the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

“This mission shows that NASA is trying to be ready no matter what the universe throws at us,” said NASA Administrator Bill Nelson.

[NASA crashes spacecraft into asteroid, passing planetary defense test]

Data from a group of Earth-based telescopes showed that the Sept. 26 collision of the DART craft — the mission’s name is Double Asteroid Redirection Test — jostled the asteroid closer to its larger neighbor, shaving 32 minutes off its nearly 12-hour orbit.

The asteroid had no chance of striking Earth, nor does any other known asteroid for at least half a century. The mission tested a technique for redirecting this asteroid as proof of concept in case future Earth folk really need to bat one out of the way.

The basic idea is simple: Hit it with a hammer! But the degree of difficulty was high, in part because NASA was aiming at an asteroid no one had ever seen until about an hour before the collision. It is a moonlet named Dimorphos that is about the size of a football stadium.

Sky watchers operating the world’s highest-powered telescopes detect the moonlet only as a shadow that crosses the larger asteroid it orbits, Didymos, as the two circle the sun together. The pair make up a “double asteroid,” a common arrangement in our solar system.

Here’s how the $330 million DART test worked: