Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 20/07/2012 09:34:19

Title: Should we blow up an Earth-bound object?
Post by: thedoc on 20/07/2012 09:34:19

Hello Naked Scientists,

If a comet were heading toward the Earth, it is often stated that the worst thing that could happen would be to break it up into pieces because then you would compound the problem.

Why?

If I want an ice cube to melt faster in a glass of water, I break it into pieces which increases the surface area. It seems to me that 100 microcraters would be a big improvement over a Yucatan-sized, dinosaur-ending type rock.

Thanks,

Andy John from Asheville NC, USA

Asked by Andy John


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Title: Re: Is it worse to blow up an approaching Earth-bound comet?
Post by: distimpson on 14/07/2012 14:20:51

I think part of why it does not make common sense is  due to the cube root, V=(4/3)pi*r^3. So, if the Yucatan impactor was 6 miles in diameter, breaking it into 100 pieces would yield 100 impactors each about 1.3 miles in diameter. Breaking it into 1000 (=10*10*10) pieces would reduce the diameter by 1/10, so 1000 objects 0.6 miles across, still pretty big impactors each with a many megaton explosion. Either way it is a bad day at the beach.

If you could vaporize the comet to dust size particles it may be a better situation but I can't say I've seen any models of the Earth running into a giant relatively dense dust cloud.

Title: Re: Is it worse to blow up an approaching Earth-bound comet?
Post by: chris on 15/07/2012 10:41:00

I agree; i think it comes down to the fact that one threat we have some hope of curtailing or mitigating, because at least the trajectory will be predictable.

But if we fragment the parent body, predicting the trajectories of the derivative pieces will be very difficult; plus, more impactors more more chances that one of them will hit somewhere important.

Chris