Bennu - an asteroid that may end life on earth

Credit: NASA/Goddard/University 

of Arizona/Lockheed Martin space

An asteroid named Bennu is approaching towards earth, and scientists have estimated that it may hit us on Thursday, September 22, 2135. It has a diameter of about 0.3 miles and its impact would create an energy equivalent to 50,000 times that of the nuclear explosion of Hiroshima. This energy is enough to destroy almost half of a continent, if not the entire planet.

Around 65 million years ago, a huge meteor 10 miles (16km) in diameter, hit the Yucatan peninsula, destroying life on earth at that time, which was dominated by the dinosaurs. The meteor made a crater 100 miles (150km) wide on earth.

Recently, a smaller meteor with size 60ft (20m), hit the atmosphere of Chelyabinsk, Russia. Its impact was almost 30 times that of the nuclear explosion in Hiroshima, and its Shockwave broke the glass of windows and injured 1500 people.

These show that there have been meteor contacts on earth, which have a considerable effect, whether it is a small meteor or a huge one. Large meteors like that in Yucatan, hit the earth in 50 to 100 million years, possibly destroying all the life, while the small ones like that in Chelyabinsk, have a comparatively lesser effect. Infact, the small meteors are quite common and hit the earth quite often, but mainly in the oceans as the 70% portion is covered by these huge water bodies.

Earth, moon and asteroid Bennu in a 

single image. This image was OSIRIS-

REx Spacecraft of NASA, in which earth

and moon are in bottom left while the

asteroid Bennu is at the top right. At the

time of capturing this image, the

 Spacecraft was at a distance of 71 million 

miles(114 million km) from earth, and 

27 miles (43km) from the Bennu asteroid. 

Credit: NASA/Goddard/University 

of Arizona/Lockheed Martin space

There is a third category of meteors, whose size are in between the above two, and Bennu falls under this category. However, the chances of Bennu hitting the earth are very less, but still if it doesn't hit and just passes by, then another one is likely to hit us anytime sooner. Hence, NASA has already a plan for this.

In a theoretical exercise, scientists at NASA are making a conceptual design of a hypothetical Spacecraft named HAMMER (hypervelocity asteroid mitigation mission for emergency response vehicle). This Spacecraft would either ram into the asteroid or destroy it with a nuclear arsenal, deflecting its path from earth in either cases. But, this would need to be done soon because everyday it is coming nearer to earth and chances of its path being deflected would also decrease with it. Even a small applied force anytime now, would surely deflect the path of any possible impact, while the greatest effort done in the last minutes won't be effective in any means.

Although, asteroids like Bennu hit the earth once in 100,000 years, and perhaps Bennu might not be the one. But, it is also inevitable that a similar rock will hit anytime. On the other hand, chances of smaller rocks to hit the land area or the habituated zone, is also not less, and in the near future any such event could destroy an entire city.

A couple of movies like Armageddon and Deep impact have dramatized such events on screen earlier.