22 November 2011

Defending The Earth From Asteroids

On Friday, 13 April 2029, Asteroid 2004 MN4 also known as Apophis, will have a close encounter with the Earth.

The asteroid will not hit the Earth.

It will be so close to the Earth that the asteroid will be passing below the communication satellites orbiting the Earth. On April 13, 2029, Apophis will fly past the Earth 18,600 miles above it. The satellites orbit at 22,300 miles.

Although the asteroid will narrowly miss the Earth, there is a small complication. It may collide with the Earth seven years later.

Upon passing the Earth, if Apophis passes thru a certain region of space above the planet called the Keyhole, which is about 600 miles wide, seven years later on April 13, 2036, the asteroid will directly collide with the Earth. April 13, 2036 is also a Friday. There is a 1 in a million chance that the asteroid will pass thru the keyhole.

Video: Neil DeGrasse Tyson discusses Apophis and the destruction it can bring

Apophis is around 1,150 (350 meters) feet in diameter, bigger than a football field. It's not big enough to wipe out civilization but can cause serious damage. The impact can be comparable to detonating a 510 megatons of TNT. In comparison, the biggest hydrogen bomb ever exploded was 50 megatons.

Scientists all over are busy finding ways to avert this disaster. China's Tsinghua University proposed launching an impactor spacecraft in a retrograde orbit, steered and powered by a solar sail. The spacecraft will move the asteroid away from the gravitational keyhole. As mentioned by Phil Plait in the video, another solution is to launch a probe that will hit the asteroid first then launch another one that will safely "tow" the asteroid away from the Earth using an ion drive. There may even be a possibility of towing it to orbit the Earth in order to mine the asteroid for minerals.

Video: Phil Plait talks about asteroid impacts, Apophis and ways to avoid a collision.

The B612 Foundation, a private foundation dedicated to protecting the Earth from asteroid strikes, estimated that if an impact with Apophis does occur, the path of the collision extends across Southern Russia, the north Pacific (near Californa and Mexico) then between Nicaragua and Costa Rica crossing Colombia and Venezual ending in the Atlantic before reaching Africa.