How To Defend Earth From A Large Asteroid Or Comet

Official Links :

JPL Asteroid Watch : http://www.jpl.nasa.gov/asteroidwatch/
Near Earth Objects Program : http://neo.jpl.nasa.gov/index.html
JPL Solar System Dynamics : http://ssd.jpl.nasa.gov/

Just a little insight the laws of physics based in the movie Armageddon are False, Blowing up an object that is traveling at a speed more then 25.000 MPH would result in being in effective to destroying a asteroid the size of Texas heading to earth, Not only would the nuclear blast blown up the asteroid into smaller objects but also its traveling speed of mass would stay intact which means the object itself would still be heading to earth not only will you take out Communication Satellites but also project the possibility of more ground impacts from the asteroid as smaller objects still head to earth.

 

The Options

1.
Direct nuclear explosions. As immortalized in the movie Armageddon, we could blow an asteroid out of the sky like so much interplanetary skeet. But there’s a catch: The pieces could still hit Earth, and we might not have enough firepower to do serious damage. It’s a last-minute, last-ditch option.

2.
Nearby nuclear explosions. Rather than blowing it up, a nuclear explosion could reroute a space rock’s trajectory clear of Earth. This would need to be done decades before the asteroid reached us. They are, after all, not easy to steer. But models suggest it could work.

3.
Laser sublimation. Several spacecraft could use machines that direct beams of concentrated sunlight to the surface of an appropriately icy asteroid. As it heats up, it’ll spew a plume of debris and change course. Of course, anyone who’s ever tried to set a ball of paper aflame with a magnifying glass knows it’s not easy. Now imagine that the ball was rotating and traveling faster than sound.

4.
Electric propulsion. To adjust course, land a spacecraft on an asteroid, fire up some rockets and push off. It’s a potentially powerful approach, but controlling that push on a spinning rock will be difficult.

5.
Gravity tractor (pictured below). Every object exerts a gravitational pull, including a single spacecraft. Merely by hovering above the asteroid, it could pull the rock off course. The approach could even be tried with the asteroid belt-exploring Dawn spacecraft, scheduled to finish its tasks by 2015. This is potentially much easier than electric propulsion, but not quite as powerful.

6.
Solar sails. Installing a photon-catching sail on an asteroid would be even harder than landing a ship, but it would certainly be prettier.

Official Links :

JPL Asteroid Watch : http://www.jpl.nasa.gov/asteroidwatch/
Near Earth Objects Program : http://neo.jpl.nasa.gov/index.html
JPL Solar System Dynamics : http://ssd.jpl.nasa.gov/