X-Message-Number: 12111
Date: Sun, 11 Jul 1999 08:16:42 -0700
From: Rand Simberg <>
Subject: Re: CryoNet #12103 - #12109

At 05:00 AM 7/11/99 -0400, Thomas Donaldson wrote:

>The only possibility of asteroid destruction comes for about the first
>75 years from now, when such efforts have not become routine and our
>abilities to deal with such asteroids remain in a primitive state. (I
>will note that nanotechnology won't be a lot of help. Asteroids are BIG,
>and deflecting them will require some large forces and/or prolonged small
>forces over a period of years). 

Well, Thomas, astronautical engineers, like myself, who are familiar with
the principles of molecular manufacturing (which I assume is what you mean
when you say nanotechnology), would strongly disagree.  

First, with respect to your last statement, assuming that it is found and
dealt with early enough, the delta V required to divert an asteroid or
comet from an earth collision course can be quite small (just as a
one-degree course change can result in a difference of many miles at the
end of a thousand mile journey).  The mass of the body itself can be used
as propellant, given some kind of sophisticated engine landed on it.  This
would be particularly easy with the ice of a comet, but even a stony-iron
meteoroid could be chewed up with mining machines and fed to an accelerator.

Second, since molecular manufacturing makes it easy and cheap to build
extremely light and strong structures, it will in general dramatically
reduce the cost of access to space (which are currently driven by the need
for high mass fractions and the containment of high-power reactions).  I
suggest that you look at some of the work of the Molecular Manufacturing
Shortcut Group (a virtual chapter of the National Space Society) for
further info.  

In short, MM will revolutionize the development of space and our ability to
manipulate its resources, so I just don't understand the above comment at
all.  That is not, to say, of course, that I am counting on it in any
way--I believe that we can develop such capabilities without it--just that
it will make it much easier.

Finally, I have no idea where you come up with the magic number of 75
years.  I expect that we will be moving asteroids for their resources in
less than twenty, with or without MM.

  * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)  
interglobal space lines  * 307 733-1715 (Fax) http://www.interglobal.org 

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