Science & technology | The Double Asteroid Redirection Test

The DART planetary defence test worked 25 times better than hoped

A step has been taken towards protecting Earth from space rocks

Astronomers using the NSF’s NOIRLab’s SOAR telescope in Chile captured the vast plume of dust and debris blasted from the surface of the asteroid Dimorphos by NASA’s DART spacecraft when it impacted on 26 September 2022. In this image, the more than 10,000 kilometer long dust trail — the ejecta that has been pushed away by the Sun’s radiation pressure, not unlike the tail of a comet — can be seen stretching from the center to the right-hand edge of the field of view.

Oct 12th 2022

It worked! The Double Asteroid Redirection Test (DART) exceeded its minimum specification twentyfivefold. This picture, taken by the Southern Astrophysical Research telescope, in Chile, shows the plume of debris ejected when that probe, which weighed 600kg, hit Dimorphos, the asteroidal moonlet of a somewhat larger asteroid, Didymos, on September 26th. The hope was to change the time it took for Dimorphos to orbit, to demonstrate how something similar might be done to the trajectory of a space rock threatening Earth. The mission would have been deemed successful if the moonlet’s orbit had changed by as little as 73 seconds. In fact, observations by telescopes on Earth, announced on October 11th, show that it changed by just over half an hour, from 11 hours 55 minutes to 11 hours 23 minutes, probably assisted by Dimorphos’s recoil from the plume’s release. The idea that an actual threat from space might thus be pushed away, is vindicated.

This article appeared in the Science & technology section of the print edition under the headline “DART’s success”