Thanks everyone for answering
It is a viable option – it’s a better option for some asteroids than others though. If you spot an asteroid long enough in advance, a little nudge will do and a nuke isn’t necessary.
The nuke option is good if you don’t have a lot of advance notice and there is a lot of surface ice or loose debris to blast away to impart maximum momentum in the opposite direction.
The idea wouldn’t be to destroy the object because that creates the potential for many smaller problems which wouldn’t be easy to handle. The idea is to use the thermal energy from the nuke to turn one side of the object into a massive rocket engine to give it a giant nudge.
The idea that ‘you cannot nuke an asteroid’ is a popular misconception. Many people seem to think that nuking an asteroid would break it apart without changing its trajectory, but this is only true if you spot the asteroid *extremely* late. In most cases, a nuclear blast would alter the asteroids orbit, so that neither it, nor the debris from the explosion, would come anywhere near the earth. This works better the more time you have.
In movies like Armageddon, they only have 18 days before impact, so in this scenario, a nuke might not work. This is incredibly unlikely to happen in real life however. We track asteroids in the solar system quite well, and we’d likely have many years, if not decades or even centuries of warning. If you can nudge the vector of an asteroid by just 1 mph, that would result in a deflection of over 80,000 miles after a decade – far larger than the diameter of the earth, so well enough to prevent it from hitting us.
>I’d rather be hit by smaller pebbles instead of an actual rock
That’s not the trade
Your choices are get hit with a big cannon ball or a blast from the biggest shotgun imaginable
The choice is irrelevant as the end result is largely the same
A single large impact can actually be less damaging because so much energy is wasted going up and down. A 2 km rock would enter with about 20,000 Megatons of energy. A 200 meter rock still enters with 200 Megatons of energy and now you have dozens of them which will ensure a more uniform devastation across the impact region
We shifted from building bigger and bigger nukes to lots of 100-250 kT warheads *because* multiple smaller explosions are more effective than a single large one. If you want to double the blast radius you need 8x the energy
Scientists did a test on the theory and it would work, very well. They predict that 99% of the mass would be removed. The catch is that you only have a window to use it – two months or more. Believe me it does in fact happen that a death rock is suddenly coming to Earth’s direction out of nowhere, it happened not too long ago. If you don’t spot them in time, you’d need to use the deflection system (pushing it or hitting with a force so hard it moves away). This was also the simulation of 1 megaton bomb with 365 foot wide asteroid (which is the size that causes the Tunguska event)
The secondary problem is that you need a massive launch vehicle to use it. Rockets are huge even to launch supplies in space. You need to build something even bigger to launch it into deep space. You’d also need to make a nuclear warhead design for this mission. If an asteroid is bigger, you’d need to scale up to even more crazy level. Only two countries in the world has this rocket and nuclear capabilities (for now): Russia and the United States.
The third problem is that let’s say you get it all dandy, well. What if it fails? It suddenly explodes half-way because of an error or something? Well, now you have nuclear waste scattering over a massive area. Seems less threatening than a rock smacking into Earth, but if you get a second one or third one launch (which is surely the case as backups or overkill), then you still have to deal with the massive ecological disaster.
Let’s say that there is no time. Well, it wouldn’t have time to break up in smaller pieces. Instead, you’d not get pebbles (which would burn up anyways) instead you would get building size rocks or bigger causing an explosive shockwave like a nuclear weapon right before hitting the ground damaging and killing countless people like a shotgun effect. It would cause massive losses of life on the shorelines as massive waves would swallows inland, it would cause widespread wildfires, total economic collapse. It wouldn’t end the world, but it would still cause the borderline collapse of human civilization as the damage would be so widespread. Imagine the Tunguska event all over the globe, it would be catastrophic on a scale that we honestly couldn’t even imagine since the Black Death.
Because now you’ve created lots of smaller objects that will fall in a wider area. They’d also be radioactive