Scifi Eye: averting an asteroid catastrophe

Dinosaurs ruled this planet for 165 million years, which probably makes them one of the most successful species ever to have existed. But that all came to an abrupt end when fate dropped a 10 kilometre-wide asteroid on them.

You’ve probably heard the old saying, ‘Hope for the best, plan for the worst.’ In engineering, it makes a lot of sense. It’s why tall buildings have lightning conductors, and bridges are designed to withstand earthquakes. When we consider that NASA estimates the number of Earth-crossing asteroids larger than 1km to be at least a thousand, perhaps it’s time to start planning for the worst.

But how can engineers mitigate the effects of a global killer?

While Hollywood imagines a team of oil drillers could drop a nuclear device into a shaft in order to split the incoming rock in two, that’s very unlikely to work in reality. Many asteroids are loosely held-together rockpiles. Setting off a nuke would simply convert one large impactor into a rain of smaller, radioactive impactors. The amount of devastation would be much the same.

If the asteroid is solid, and caught early enough, a nearby blast might be enough to nudge its trajectory enough to miss us, but if it isn’t particularly stable, you again run the risk of turning it into a shotgun blast of smaller rocks.

So what else can we try?

We could try attaching a rocket motor to it. Some kind of low-thrust ion motor might be capable of achieving a course alteration without structurally destabilising the asteroid. But that would take some time, so we’d need the capability to reach the asteroid and attach the motor while it was still some distance out.

We could fire a laser at it. A large enough laser, assuming one can be built and placed in position in time, could be used to heat one side of an incoming body, which would cause trapped gasses in the rock or ice to expand and act like a thruster, pushing the asteroid or comet onto a new course. The trouble with this plan is that any space-based laser with that amount of power would be a ferocious weapon, able to strike any part of the Earth’s surface.

Indeed, as Carl Sagan noted, any method capable of deflecting impactors away from Earth could also be abused to divert non-threatening bodies toward the planet. A rock only 100 metres in diameter could be easily capable of wiping out a large city, as it would strike with more energy than a 50 megaton bomb.

In the recent Amazon movie, Greenland, the governments of the world construct bunkers buried deep in the Earth in order to shelter essential members of the population. But bunkers like these would have to be deeper and more resilient than anything built during the Cold War. If something the size of Snowdon comes at you travelling 300,000 kilometres-per-second, you’re going to need some hefty shielding.

If we’re going to look at this from a science fiction point-of-view, it might actually be easier to evacuate key personnel into orbit ahead of the impact, as in Netflix’s recent satirical drama, Don’t Look Up. However, the challenge of constructing and maintaining a viable space habitat for a large number of people, not to mention the amount of rocket launches needed to ferry them up there, makes this a far-from-simple option, and certainly not achievable unless we have a lot of advanced notice.

Perhaps one day, we will develop the ability to open an Einstein-Rosen bridge, or wormhole. These are theoretical structures that link two disparate locations in space and time. They have appeared in Star Trek, The Expanse, and the movie Interstellar, and are usually seen as a way to travel to distant star systems without having to cover the intervening distance. But what if we used one for defence?

If a large comet or asteroid came at the Earth, we could manoeuvre one end of the wormhole between us and it, so that the potential impactor passed into the hole instead of hitting the Earth. It would then be up to us to decide where it would emerge. In the heart of the sun, perhaps, or maybe way out in interstellar space, where it wouldn’t become a threat again on its next orbit around the sun.

Asteroid impact seems like a science fiction problem, but it’s a real possibility. To ensure our survival, we’re going to have to dream up some science fiction solutions.  

Gareth L. Powell is an award-winning and widely lauded author at the forefront of speculative fiction. He has won the British Science Fiction Association (BSFA) Award for Best Novel twice, and been a finalist for the Locus, British Fantasy, and Seiun awards. He can be found on social media @garethlpowell