A meteorite 50 feet wide blazes a trail through the skies of Siberia, Russia, before exploding in a fireball with a force thrity times stronger than the atomic bomb that was exploded over Hiroshima. At almost the exact same time, an asteroid, named 2012 DA14, over three times larger comes within 15,000 miles of the Earth's surface, less than a tenth the distance to the moon and closer than many satellites. Fortunately, it doesn't hit our planet, but if it had, it would have hit with the force of a thermonuclear bomb, and could have completely destroyed a city. What is going on here?
According to NASA, incidents like the one in Siberia happen on average about once a century. The last one also happened in Siberia, in the Tunguska region, in 1908, and was considerably more powerful than the one that just happened, flattening an entire forest. While it is fortunate that the larger one didn't hit us, objects that big and bigger have hit us in the past; just look at Meteor Crator in Arizona. An asteroid about three miles in diameter impacting what is now the Yucatan peninsula in Mexico is deemed by scientists to be primarily responsible for the extinction of the dinosaurs. According to scientists at NASA, the probability of something likd that happening again in the near future is very remote; however, they also said that the probability of two events like the meteor in Siberia and the one that just missed us happening at the same time is about a million to one, and if another large asteroid does manage to hit us, we, not the dinosaurs will be the ones to become extinct.
While all this may sound like a bad science fiction movie, the events of last weekend have pointed out that our planet being hit by an asteroid is a real problem that shouldn't be ignored. While the chances of it happening at any given time are remote, if it does happen the consequences will be so devasting that it could affect life on Earth for a long time, even if it doesn't end it. NASA itself admits that it only knows of the location of about one-third of the NEO (Near Earth Objects) that have the potential to someday hit us. The asteroid that just passed us by wasn't discovered by astronomers until fairly recently, and the smaller one that exploded over Siberia was never discovered until it hit us. Even if we did discover that a large asteroid was going to hit us in, say, a year, right now there is little we could do to alter its path or destroy it.
What are some of the proposed options in dealing with such a situation? Basically, if we were to discover a large asteroid headed for earth, the two options we would have are; one, to change its path so that it misses us, and two, to destroy it. Destroying it would be a possibility if we could hit it with enough explosive force, but right now all the nuclear-tipped ICBMs we have are pointed at each other, not space, and we would need time to do the calculations and reprogram the computers so they could be targeted at an object in space. Furthermore, if we don't hit the asteroid with enough force and exactly in the right place, like splitting a diamond, the asteroid, instead of being destroyed, could fracture into two or more large pieces, and as we know from watching movies like Deep Impact, that would not be a good thing.
The second option we would have, since Bruce Willis presumably wouldn't be available, is to find some way of changing the path of the asteroid so that it missess the Earth. This could be done, but only if we had enough warning. Another problem is that, unfortunately, we have yet to invent a tractor beam as portrayed in Star Trek, although there was a report in the scientific press last week that some scientists were actually working on just that. There has also been a proposal to deploy satellities in space that could use either nuclear or solar power to generate powerful laser beams, which could be directed at the asteroid so as to alter its path. This is similar to the Strategic Defense Initiative (SDI) program proposed by President Ronald Reagan in the 1980s, only in this case the target would be the invading asteroid, rather than man-made missiles. We probably have the technolog to do this, but it would be very expensive, and the question is, do we have the will?