For many people, the threat of an asteroid harming them is either nonexistent or too outside of their control for them to care. It’s something most people only think about after watching “Armageddon” or “Don’t Look Up.” Although such an event is unlikely to happen, its effect can be huge. I am not just talking about an extinction-level event, but rather something comparable to a natural catastrophe such as an earthquake, hurricane, or tsunami. With a BIG difference: an asteroid hitting the Earth can be predicted years in advance. This advance warning won’t go to waste, as there are already multiple promising technologies capable of deflecting the asteroid off its path to Earth.
Kinetic Impactor
Imagine you are playing pool and you hit one ball with another. The moving ball crashes into a still ball and makes it roll away. The same idea is applied to an asteroid. We send a spacecraft to crash into the asteroid. When it crashes, it gives the asteroid a small push that changes the asteroid’s orbit enough to make it miss Earth.
In September 2022, a spacecraft known as DART, sent by NASA, successfully crashed into an asteroid and changed its orbit. This mission was only a test, but it was the first demonstration that we can actually change an asteroid’s path.
Nuclear Blast
Think of it like this — you blow up a nuke on the surface of the asteroid. When it explodes, it turns a chunk of the asteroid into a dusty gas which shoots off at high speeds. This gas then pushes the asteroid in the opposite direction; it is the same principle as when you let go of a balloon and the air coming out pushes the balloon around the room.
Ion-beam Shepherd
Think of using a hair dryer to move a ping-pong ball across a table. That’s the basic idea behind this method. The spacecraft parks itself near the asteroid and points its engines towards the asteroid. The “air” coming out pushes the asteroid and slowly changes its orbit.
Gravity Pull
The idea is simple. Imagine placing a spacecraft near an asteroid. Just by being close to it, the spacecraft’s gravity will pull the asteroid and over time change its orbit. The heavier the spacecraft, the faster this process would be.
Laser Ablation
This uses the same principle as the nuclear blast method, but instead of using a nuclear explosion to turn rock into a dusty gas, we use a high-powered laser. The gases will float away and push off the asteroid.
There is an alternative to this method that, instead of using a laser, uses mirrors to focus the energy of the sun into the asteroid. This method would be called Solar Ablation.
Mass Drivers
This is my favorite method, though it’s probably the most technologically challenging. Picture a swarm of mining spacecraft landing on an asteroid. These spacecraft drill into the surface and collect chunks of rock. But here’s the exciting part: they’re equipped with “cannons,” called mass drivers, that fire these rocks into space. Each shot creates a reaction force that gently pushes the asteroid in the opposite direction, gradually shifting its orbit.
Are we safe?
All of these methods have one thing in common: they all take years to make meaningful changes in an asteroid’s orbit. With enough advance notice, we have the technology and expertise to deflect an asteroid. But what if we don’t have enough time? Well, to guarantee that we do, space agencies worldwide are scanning the sky daily, looking for new asteroids that could pose a threat to Earth in the future. But what if that isn’t enough? Well, then we always have nukes…
