WASHINGTON: Nasa will attempt a feat humanity has never before accomplished: deliberately smacking a spacecraft into an asteroid to slightly deflect its orbit, in a key test of our ability to stop cosmic objects from devastating life on Earth.

The Double Asteroid Redirection Test (DART) spaceship launched from California last November and is fast approaching its target, which it will strike at roughly 14,000 miles (22,500 kilometers) per hour.

To be sure, neither the asteroid moonlet Dimorphos, nor the big brother it orbits, called Didymos, pose any threat as the pair loop the Sun, passing about seven million miles from Earth at nearest approach.

But Nasa has deemed the experiment important to carry out before an actual need is discovered.

If all goes to plan, impact between the car-sized spacecraft, and the 530-foot (160 meters, or two Statues of Liberty) asteroid should take place at 7:14pm Eastern Time (2314 GMT), and can be followed on a Nasa livestream.

By striking Dimorphos head on, Nasa hopes to push it into a smaller orbit, shaving ten minutes off the time it takes to encircle Didymos, which is currently 11 hours and 55 minutes — a change that will be detected by ground telescopes in the days that follow.

The proof-of-concept experiment will make a reality of what has before only been attempted in science fiction — notably films such as Armageddon and Don’t Look Up.

Technically challenging

As the craft propels itself through space, flying autonomously for the mission’s final phase, its camera system will start to beam down the very first pictures of Dimorphos.

Minutes later, a toaster-sized satellite called LICIACube, which separated from DART a couple of weeks earlier, will make a close pass of the site to capture images of the collision and the ejecta — the pulverised rock thrown off by impact.

LICIACube’s pictures will be sent back in the weeks and months that follow.

Also watching the event: an array of telescopes, both on Earth and in space — including the recently operational James Webb — which might be able to see a brightening cloud of dust.

Finally, a full picture of what the system looks like will be revealed when a European Space Agency mission four years down the line called Hera arrives to survey Dimorphos’s surface and measure its mass, which scientists can only guess at currently.

Published in Dawn, September 27th, 2022