Re: Asteroid Problem

[Ludwik Kowalski <kowalskiL@MAIL.MONTCLAIR.EDU>]

What if nuclear fusion is used as a source of power for
giant rocket engines placed on the asteroid (in order to
change its orbit)? The material (ice and rocks, but not
iron) from which the celestial object is made can, in
principal, be used as fuel. Developing such engines,
and the technology for placing them effectively on
asteroids, may be a worthwhile "insurance policy."
Ludwik Kowalski

"Daniel L. MacIsaac" wrote:

> > for the "hard sciences."  Recently my grandson, age 9, and I have been
> > playing a thought game regarding the best way to precisely deflect an
> > earth-bound asteroid into a benign orbit around the earth.  He suggested
>
> > 2.      What would be the best way, using current technology, to deliver this
> > energy to the surface of the asteriod?  High energy lasers such as the
> > ones being developed by DOD? Or accelerating hydrogen nuclei [i.e., a
> > proton beam] at very high relativistic speeds? Or some other way?
>
> A great problem; I actually heard a lecture by Freeman Dyson given on this
> topic at Purdue University about 8 yrs ago.  Unfortunately, I was unable to
> find anything on that talk online, but perhaps he published it somewheres.
>
> Dyson started the lecture with an actuarial analysis of the problem --
> impacts only occur once in a great long while, but since destruction of
> property and loss of life were nearly total for the planet the problem is
> worth financially addressing via research (buying insurance).
>
> The gist of Dyson's analysis was that nuclear devices are lousy for changing
> momenta, which is what you need.  Even pulverising an asteroid just means
> you get whacked with a lot of high kinetic energy gravel which is not much
> better than a solid asteroid -- the KE still get dumped rather traumatically
> into the atmosphere.  His real analysis focussed on how far out you could
> still land on such asteroids and erect mass throwers on the surface to
> deflect the asteroid.  You need to fling a lot of mass over a lot of time,
> and the earlier you start the better off you are.  The conclusion wasn't
> very optimistic yet, but in a century or two (assuming our luck holds)
> we are in good shape.  Until then, we should be surveying as frantically
> as we can.
>
> Dan M
>
> Dan MacIsaac, Assistant Professor of Physics and Astronomy, Northern AZ Univ
> danmac@nau.edu          http://purcell.phy.nau.edu         PHYS-L list owner