There have been movies made about it. And some believe it will happen in 2012. A massive asteroid, meteor or comet threatens to destroy life on Earth as we know it. Only this scenario is not relegated only to movie theaters and science-fiction novels. There is a real possibility that a large object could one day be on a collision course with Earth. The question becomes, is there anything that we can do to stop the apocalypse?
The Key is Early Detection
History tells us that large comets or asteroids periodically collide with Earth, and the results can be devastating. There is evidence that a large object collided with Earth about 65 million years ago and caused the extinction of the dinosaurs. More recently, a iron meteorite impacted the Earth in modern day Arizona, leaving a crater that is 34 miles wide. Such a collision almost certainly destroyed all life within hundreds of miles from the impact site.
Clearly these types of collisions do not happen very often, but when one does come along, what do we need to do to be ready?
The more time that we have to prepare a plan of action the better. Under ideal circumstances we would have years to prepare a strategy on how to destroy or divert the object in question. Surprisingly, this is not out of the question.
With such a large array of optical and infrared telescopes scanning the night sky, NASA is able to catalog and track the motions of thousands of Near Earth Objects (NEOs). Does NASA ever miss one of these NEOs? Sure, but such objects usually pass right by Earth or burn up in our atmosphere. When one of these objects does reach the ground, it is too small to cause significant damage -- loss of life is rare. If a NEO is of significant enough size to potentially threaten life on Earth NASA has a very good chance of finding it.
The recently launched WISE infrared telescope will conduct a complete survey of the sky and should find any and all NEOs that are potential planet killers. But just because we don't detect any now, does not mean that we are safe forever. This is a continual process since the NEOs need to be close enough for us to detect, so there may be some coming this way that we just can't see yet.
How Do We Stop Asteroids From Destroying Earth?
Once a NEO is detected that could threaten Earth, we will devise a plan to prevent a collision. The first step will be to gather information about the object. Obviously the use of ground based and space based telescopes will be key, but it will likely extend beyond that.
NASA will hopefully be able to land a probe of some sort on the object so that it can gather more accurate data about its size, composition and mass. Once this information is gathered and sent back to Earth for analysis, scientists could then develop the best course of action for preventing a devastating collision.
The method used to prevent a cataclysmic disaster will depend on how large the object in question is. Naturally, because of their size, larger objects can be more difficult to prepare for, but there are still things that we can do.
- Nuclear Bomb: One of the easiest approaches to preventing a large collision is to try and divert the object from its course. There are several ways that NASA could do this. The first would be to detonate a nuclear weapon, or some other powerful bomb strategically near the object. The blast would knock the object off course.
- Rocket Motor: Alternatively, a rocket or motor could be attached to the object, and used to drive it onto a new course. In either case, it would not require a significant deviation of course to cause it to miss us, especially if there is an early detection. If launched early enough, a change of course of less than one degree could cause the object to miss the Earth by millions of miles.
- Solar Sail: Another proposed defense is to use the power of the Sun to help divert the object. The solar energy from the sun can actually apply pressure on an object. So a sail could be attached to the object to harness the solar wind, similar to how we use sail boats here on Earth, and divert the course of the object that way.
- Break The Object Up: NASA could also use a weapon to break the object up into smaller pieces. In theory this would accomplish two tasks, it would cause most of the pieces to miss Earth by changing their direction. But, more importantly, it would break the object up into such small pieces that even the ones that made it to Earth would likely burn up in the atmosphere. Sounds good in theory, but this would actually be very difficult to do well and would require extensive knowledge of the object and careful planning. This would be most effective on smaller objects.
Obstacles Still Remain
With the previously mentioned defenses in place we should be able to prevent future planet-killing collisions. The problem is that these defenses are not in place, some of them only exist in theory.
Only a very small part of NASA's budget is designated for monitoring NEOs and developing technology to prevent a massive collision. The justification for the lack of funding is that such collisions are rare, and this is evidenced by the fossil record. True. But, what Congressional regulators fail to realize is that it only takes one. We miss one NEO on a collision course and we don't have enough time to react; the results would be fatal.
Clearly early detection is key, but this requires funding and planning that is beyond what NASA is currently being allowed. And even though NASA can find the largest and deadliest NEOs, those 1 kilometer across or more, rather easily, we would need dozens of years to prepare a proper defense -- a forewarning that we may not readily have. The situation is worse for smaller objects (those a few hundred meters across or less) that are more difficult to find. We would still need significant lead time in order to prepare our defense. And while collisions with these smaller objects would not create the widespread destruction that the larger objects would, they could still kill hundreds, thousands or millions of people if we don't have enough time to prepare. Time we may not have unless the government begins taking these threats more seriously.