Is there anything we could do to stop an asteroid?
Kinetic impactor
Kinetic impactors are one way by which we might be able to alter an asteroid's path. In principle, this technique requires smacking an asteroid to change its orbit around the sun so it no longer is a threat to Earth.
This could be done by impacting it with a non-destructive projectile, simply tugging the asteroid into a different orbit with a nearby high-mass spacecraft, ablating the asteroid's surface with a high-power laser (or a nearby nuclear explosion), or by placing small rockets on the asteroid's surface.
“We would estimate that it would take energy equivalent to about 200 gigatons of TNT to fully disrupt an asteroid with a 20-kilometer diameter,” Ramesh says. (This is roughly double the estimated size of the asteroid or comet that is believed to have killed the dinosaurs.
Using high-fidelity simulations, scientists reported in a study published earlier this month that a stealthy asteroid as long as 330 feet could be annihilated by a one-megaton nuclear device, with 99.9 percent of its mass being blasted out of Earth's way, if the asteroid is attacked at least two months before impact.
An asteroid on a trajectory to impact Earth could not be shot down in the last few minutes or even hours before impact. No known weapon system could stop the mass because of the velocity at which it travels – an average of 12 miles per second.
As a proof of concept on a small scale, Travis Brashears, a researcher at UC Santa Barbara's Experimental Cosmology Lab, led by Dr. Philip Lubin, has already experimentally verified that laser ablation can de-spin and spin-up an asteroid.
The good news is: an asteroid or comet impact is a natural disaster we can actually prevent—if we try. The effort to prevent asteroid or comet impacts is called planetary defense.
Their experiments showed that blowing up a 200-meter asteroid would require a bomb 200 times as powerful as the one that exploded over Hiroshima in 1945. They also said it would be most effective to drill into the asteroid, bury the bomb, then blow it up—just like in the movie Armageddon.
“Any asteroid over 1km in size is considered a planet killer,” said Sheppard, adding that should such an object strike Earth, the impact would be devastating to life as we know it, with dust and pollutants kicked up into the atmosphere, where they would linger for years.
Ultimately, scientists estimate that an asteroid would have to be about 96 km (60 miles) wide to completely and utterly wipe out life on our planet.
Can we protect Earth from asteroids?
The good news is: an asteroid or comet impact is a natural disaster we can actually prevent—if we try. The effort to prevent asteroid or comet impacts is called planetary defense.
NASA confirms that its DART spacecraft 'nudged' the asteroid Dimorphos into a new orbit. Humans have for the first time proved that they can change the path of a massive rock hurtling through space.
An asteroid on a trajectory to impact Earth could not be shot down in the last few minutes or even hours before impact. No known weapon system could stop the mass because of the velocity at which it travels – an average of 12 miles per second.