how we're hunting for killer asteroids with space radar

NASA proved we can redirect incoming asteroids. Now we just need to find them before they find us, and we think we might know the best way to do it.

Dinosaurs living 65 million years ago had a really rough day, one we probably wouldn’t want to repeat because of all the dying and extinction that will happen, us included. In even worse news, we don’t need to have a another asteroid the size of Mount Everest hit us to straight up not have a good time. Since the kinetic energy of any impact is a product an object’s momentum, not just its size, a kilometer long rock in space that’s moving really fast — which, spoiler alert, is all of them — can wreak global havoc with blunt force if it slams into a major city, or massive tsunamis if it hits the ocean, as it’ll be most likely to do, seeing how they cover the majority of the planet.

Okay, that was the bad news. The good news is that NASA launched a mission to see if we could nudge a space rock off course and prevent an impact we know is coming, and it worked splendidly. Yes, yes, no need to send Aerosmith and Bruce Willis to save us on short notice, we can do all of this remotely. (Related, if we can save the Earth in our PJs from home, why do we need to return to the office to update spreadsheets?) But the only problem we now have is that the effort to track down potential impactors is not as well funded as we’d like, and we’ve been relying on mostly luck and overtime from dedicated asteroid hunters.

Enter deeply pocketed defense contractor Raytheon, the Green Bank Telescope, and the Very Long Baseline Array. Using just 700 watts of power — barely enough to warm up your leftovers in the morning — the trio produced insanely high resolution images of the Moon with a radar array, catching anything larger than five meters from nearly a quarter million miles. And that was just a proof of concept. The planned 500 kilowatt system could spot anything even remotely big enough for us to think about furrowing our brows in concern even if it’s over two million kilometers above us, which is exactly for what it’s intended.

As the planet spins around its axis, it could actively scan the skies on a regular basis with no concern about the time of day since it’s not using light. However, if we want a true planetary defense system, we would need multiple installations just like it in both hemispheres at the very least. If enough similar arrays can take a snapshot of the full sky every day, we’ll have a pretty decent advanced warning system that will help us either deflect incoming objects, or prepare for the worst with rapid evacuations prior to impacts. This will require a global alert system and worldwide coordination, but we won’t always have the luxury of an early warning and time for a redirect mission.

Here’s even more good news. According to NASA, we’re almost certainly safe from a major impact for the next century, and there’s only a small chance that anything fast and heavy will hit us in the next 1,000 years. We have time to get our act together, so it’s great news that we’re starting now. After all, one missed asteroid half a kilometer wide could still ruin our year, and hundreds of millions of lives, trillions of dollars, and, oh, right, the potential end of humanity, is nothing to take lightly.