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Q & A: avoiding collisions with the Earth

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Most recent answer: 08/27/2013
I was wondering if it was possible to slow down meteors that enter our atmosphere enough so that they would burn up and not make it to our surface. If so, how much would we have to slow them down to make a difference?
- Bader Semakieh (age 16)
Normal, IL, USA

Some meteors (dubbed meteorites) do make it to the surface. I have one on my mantle piece. Most don't.

I'm not an expert, but I think that the effect of speed is the opposite of what you may be implying. A very fast meteor has lots of kinetic energy that gets converted quickly to heat. That can cause the meteor to ablate (evaporate) completely, sometimes ending with an explosion. A more slow-moving meteor has less kinetic energy and longer for it to dissipate away via thermal radiation and convection. So I think slowing one increases its chance to reach the surface.

Larger objects, such as asteroids, present a more important practical problem. If one wanted to avoid the dangers of a larger object hitting the Earth, or exploding in the atmosphere, the method would be to spot it far away and use a rocket to nudge it to miss the Earth altogether. Since occasional catastrophic asteroid hits do happen, there has been much talk of setting up an international program to do just that.

Mike W.

(published on 08/27/2013)

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