Re: Comet deflection capability

From: Greg Campbell (nospam_at_null.net)
Date: 06/11/04 

Date: Fri, 11 Jun 2004 12:54:34 -0700

David Dalton wrote:

>>In real life, the most effective way to divert an asteroid
>>or comet is with a salvo of proximity-fuzed nuclear missiles
>>detonating nearby, not nuclear weapons buried deep inside.
>
>
> Wouldn't the ejecta from the hole act as a jet to
> push the body aside?

To a degeee. It's much simpler to detonate the bomb a modest distance
from the target. The intense radiation vaporizes the surface, creating
a strong jet/rocket effect. This also has the big advantave of
distributing the jetting forces over a much wider area. You want to
push the object, not fracture it.

> Also if there was fragmentation,
> many small impacts is better than one big impact.
> (If a comet was in a thousand pieces a higher percentage
> would burn up before impact, for one thing.)

It's the kinnetic energy of the object that causes the damage. If you
took a rock 5 mile across and gently lowered it it on Tokyo or NYC (the
historic favorites for spectacular destruction) you would have a 5 mile
wide pancake. Areas a short distance away would escape damage. The
same rock going umpteen thousand miles per hour will take out half a
continent and damage most of the planet.

As for your thousand pieces. Yes, they would all burn up....dumping all
their kinnetic energy into the atmosphere. Zorch.
The same object, if intact, will 'bounce' off the earth before dumping a
little less energy into the air. The regional and global effects would
be different but it wouldn't really matter.

>>Furthermore, in real life it's a lot easier to divert an
>>asteroid or comet a year before impact than it is a week
>>before impact. Even if you factor in the cost of building
>>the dedicated network of telescopes that guarantees you a
>>year's advance warning.
>
>
> Not always, but yes I underestimated the time that
> would be available there, and should have quickly
> researched comet detection on the web first before
> posting.

Consider the movie 'Armageddon' (the WORST hit movie of all time, I
might add). At the end, mere minutes before impact, Bruce pushes the
button and the nuke blows the comet(?) apart. The pieces ZOOM away,
missing the earth on either side. How fast were those pieces going?
How much energy does it take to accelerate umpteen million tons to
speeds of several thousand miles per hour? It can't be done. The
accelerative forces required would simply pulverize the comet, leaving
most of it on the same trajectory. Zorch.

To deflect a fragile ball of rock and ice, you need to push gently for a
long time, or push gently a long time ago. A comet that is scheduled to
hit earth several years from now needs only a gently push; slow or alter
it's course by less than a mile per hour and <SHAZAM!> it misses Earth.
  This method is much less dramatic, but also much more effective.

> But of course you are not the cult atheist sort
> who would say that even if there was evidence
> of it, right?

You have evidence? James Randi will give you a million dollars! Enjoy
your mansion and private jet. (OK - fixer-upper and ultralight.)

-Greg

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