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Any attempt at asteroid deflection relies on early detection of the threat. It would take a couple of years to build a missile that could carry an explosive device powerful enough to deflect an asteroid and have time for the deflection’s effects to widen the orbit enough to miss Earth. Even though there have been a few potentially hazardous objects (PHOs), asteroid deflection is still a thing of conjecture, but exciting conjecture none the less.
The Asteroid Deflection Research Center was formed at Iowa State to bring researchers from every nation together to attack the issue of asteroids striking the Earth. Some of these researchers have been studying the problem since the early 1990s, but have not reached a common theory. The need for preventative measures was reinforced by the Tunguska event in which over 80 million trees were destroyed by a small meteorite exploding above the earth just 100 years ago. The devastation that such an event would wreck if it hit an urbanized area is too mind boggling to express.
The most common thought of method to effect an asteroid deflection is a nuclear bomb. Non-nuclear alternatives have been found to be much less effective and harder to predict. Still, more research is needed to verify the effectiveness and practical viability of a nuclear approach. A 20 meter stand off distance is often mentioned to achieve a maximum velocity change, but no one is for certain. With over 900 known PHOs, there is a definite reason to continue the research.
The non-nuclear methods of asteroid deflection include kinetic impactors and slow-pull gravity tractors, possibly relying on solar sail technology. Another method that is being studied is the combination of both nuclear and non-nuclear methods. The theory is that a nuclear bomb would be exploded to force the major velocity and course correction then a gravitational tractor will be deployed to further correct the asteroid’s orbit away from Earth.
The immediate need for asteroid deflection is not great, but the future will hold even more of a threat from PHOs. Scientists admit that the frequency of an extinction class object striking Earth is only once in every 50-100 million years. The precision orbital guidance systems that are being developed from this research will have more immediate uses, so there is some good use immediately.
Although, there may not be any immediate need for asteroid deflection scientists are working hard for future use. The astronomy community is looking forward to the advances in propulsion and guidance systems that will come out of this research.
ISU Asteroid Deflection Research Center