What would happen if an asteroid migrated into the cosmic billiards and then headed for Earth? NASA asked this question a long time ago. There are plans that are initially only theoretical. But as you know, dear reader, it is always better to try to better deal with these small events. In this case, a planetary disaster. So NASA will distract an asteroid to test how its emergency plan works.
This is the DART (Double Asteroid Redirection Test) mission. A spaceship will crash on the smallest asteroids in a binary system. It will be easy to measure changes in the orbit of the smallest object from Earth. And it’s a good indicator of whether you’ve been redirected successfully.
In search of the killers
“DART will be an extraordinary demonstration,” said Ed Lu, a retired NASA astronaut. He is the founder of the B612 Foundation, which is dedicated to the discovery and distraction of asteroids.
The first step in stopping a killer asteroid is to find it. “There are literally hundreds of thousands of asteroids,” says Lindley Johnson. He is a NASA planetary defense officer. The catalog contains 2,078 potentially dangerous asteroids.
NASA classifies any object over 140 meters wide that travels eight million kilometers as potentially dangerous. In seven years, the 1990MU asteroid (three kilometers wide) will be five million kilometers from Earth. “We don’t want something that big to have an impact,” says Johnson. «Our main task is to find them. And complete the catalog of everything there.
Asteroids a kilometer or more would wreak havoc across an entire continent. They would cause a drastic cooling and the possibility of poor harvests for years.
Even space rocks less than 150 meters wide can be extremely dangerous. Some meteors explode with the power of atomic bombs in the sky. Like in Chelyabinsk, Russia, in 2013. Nobody saw it coming.
Prevention is the key
With years or even decades of preparation, we could take large asteroids off course. The DART mission will crash a half-ton spaceship on an asteroid. In October 2022, the refrigerator-sized spaceship approached an 800-meter-wide asteroid. It’s called Didymos and is orbited by a moon about 150 meters wide. This moon is being hit. If they manage to change their orbit, it will be a success.
Kinetic impactors could successfully redirect a small asteroid. But what if it’s big? Lu points out that we would need a larger strategy if such a large object were on a collision path with Earth. How to detonate an atomic bomb near the asteroid to evaporate part of its surface and distract it from its course. But it could emit a flood of fragments towards Earth.
The optimal redirection strategy depends on both the incoming object and the time we have before the impact. So NASA will distract an asteroid: to know if it works, you have to practice. A little preparation makes a big difference.