New research has been published detailing how even current technology might one day save our planet from a devastating collision with asteroid Bennu, one of the potentially dangerous near-Earth objects.
Asteroid Bennu is now mostly known for having been visited by NASA’s OSIRIS-REx – the spacecraft is slowly coming back to Earth with a precious sample of material from it. But there’s another concerning fact about Bennu: the asteroid has a one-in-2,700 chance of hitting us on September 25, 2135.
On that Sunday morning, Bennu will pass Earth five times closer than the Moon, based on current estimates. The uncertainty is still wide enough that it might hit our planet or miss it, but it remains concerning. Bennu is over 500 meters (1,640 feet) across, and an impact would release 1,200 megatons of energy. That’s 24 times the yield of the Tsar Bomba, the most powerful nuclear weapon ever built and tested.
But worry not! Even if we discover that the impact is going to happen, it doesn’t mean it’s inevitable. Researchers from the US have previously released a plan showing an impactor called HAMMER designed to deflect the dangerous space rock. Now, Chinese researchers have released their own plan, that also relies on existing technology.
The work, published in the journal Icarus, focuses on the kinetic impactor approach to deflect an asteroid. A spacecraft is crashed onto the asteroid, giving it a little nudge. With enough time and enough impacts, you can shift the asteroid enough to avoid Earth completely.
The proposed system is called the Assembled Kinetic Impactor (AKI) because instead of having the impactor separating from the rocket when it gets to leave Earth’s orbit, the rocket comes along for the ride, adding mass to the impact. Using the technical data of the Long March 5 (CZ-5) launch vehicle, Bennu’s trajectory could be deflected by 1.4 Earth’s radii (8,900 km/5,550 miles) with 23 successful impacts of such rockets.
With just a 10-year lead-up time, this would be enough to change the asteroid’s orbit and save Earth – and you wouldn’t need a nuclear weapon to accomplish that. The Chinese approach is a little more efficient in terms of launches compared to HAMMER. Back in 2018, the team estimated that it would take between 34 and 53 HAMMER impacts to shift Bennu with a 10-year lead before impact.
While Bennu is currently not a threat, there are other bodies that might be. With a 10-year lead-up time, a single AKI could deviate a 140-meter-diameter (459 feet) asteroid by more than one Earth radius. Having something like this ready could be a life-saver.