We all see the apocalyptic social media posts of a doomsday event. Mainly an asteroid or supersized fictional planet impacting the Earth. Everyone hid under a rock in 2012 thinking the world as we know it was going out in a blaze of glory!
It is accepted that a large asteroid collided with the Earth during the late Jurassic Period resulting in the extinction of the dinosaurs. The effect was similar to a modern nuclear strike in which hundreds of millions of soot and organic material were plunged into the atmosphere, blocking the Sun’s light and heat causing the Ice Age.
So was this extinction event a one off? Absolutely not! Every so often, approx every 100,000,000 years. So within the next 45 million years we are due a mass extinction event. Within all of physics and orbital mechanics, the precision of an extinction event is extremely difficult to determine so a plan needs to be put in place for the event of a large asteroid heading towards the Earth.
NASA have contingency plans for the sighting of an asteroid with a calculated collision course towards the Earth. With differing circumstances different plans are in place. Both plans depend on the mass and velocity of the asteroid and how long we have to react.
So if all goes in favour of mankind, the plan to avert the asteroid is by using what NASA call a gravitational tractor. A large craft would be launched into the proximity of the asteroid with a view to the gravitational power of the craft averting the asteroid. Should the craft draw the asteroid to it, it could minimise damage to the Earth or send it on a course around the Earth entirely.
Time to get Hollywood. If an asteroid is observed much too late it is time for the cooler plan. Nukes! If it is too late for a gravitational tractor to be inserted into or near the orbit of the asteroid, we need to destroy it. Of course this depends what it is made of!
The most powerful bomb built by humans is the Tsar bomb. Should the bomb be launched into orbit it would be a huge gamble to wether it would actually work and if it would send a shower of debris towards the Earth. That would be a galactic equivalent to spotting the iceberg too late.
So there are plans in place for the event of an apocalyptic asteroid hurtling toward the Earth. Wether they work or not depends on the size and velocity of the asteroid and if we see it on time. To increase our chances of survival, keep using your telescopes!