X-Message-Number: 12116
From: Thomas Donaldson <>
Subject: for Rand Simberg: why I chose 75 years
Date: Tue, 13 Jul 1999 00:09:56 +1000 (EST)

For Rand Simburg:

While I do not plan to argue about the exact number of 75 years (I meant
it to be approximate) I will explain that figure here. I was not just 
taking account of the required TECHNOLOGY. I was also discussing the
politics and the vision of people at large. That is why I came up with
a figure longer than you seem to expect.

First of all, most people have no idea of this particular danger. This
includes lots of politicians. The very first thing we'd need to do is
to set up a network to FIND such asteroids, and that in itself has
not proven easy. There's no problem about the technology required; it's
a matter of competing with all the other things that people and their
politicians want, in a context in which most people would think that
asteroids colliding with Earth belong only to science fiction. And if
most of your friends think that asteroid collisions are a real problem,
I'll have to say that (like anyone else, really) you've selected your
friends. (I think it is a real problem, too, incidentally).

Right now we do not have a telescope network wide enough to capture many
asteroids which might collide with the Earth. I do not know how long
it will take to get such a network; clearly it is the very first
requirement of ANY system for dealing with dangerous asteroids that we
first know of them AND their orbits.

So we must tack on some extra years to your 25 year estimate. 

Then we have some other problems (all political, as I've said). First of
all, to use slow methods we need to have good data on the (unaltered)
trajectory of the asteroid literally years before we get to work. If
we discover an asteroid likely to collide with the Earth only (say)
2 years in the future, we have a problem. We'll need much more powerful
ways to giving it an impulse. One obvious powerful way consists of 
nuclear explosions, but that is quite certain to run into political 
problems, too ... with things such as Test Ban Treaties (Oh, those 
Americans have just found a clever way to get around the Test Ban
Treaty!). Even if we can deal with it otherwise, the earlier it is found
the more expensive will be our means to deal with it. I can see Congress 
full of speechmaking etc on just this subject; and I do not believe that
in just 10 years some independent small group will have the required
resources to deal with such an asteroid on their own.

The political side can get even worse. As an observer you might easily
do perfectly fine work, and have good data. I guarantee that if you
go to politicians for funding your expertise and or objectivity will be
questioned and some people will insist that a SECOND study be done to
verify yours.

Yes, I don't like politics and the need to educate lots of people in
a democracy in order to get something like this done. (Dictatorships
of course have even worse problems! Then you have to educate the 
dictator, who'll probably be very skilled in the use of political power
but totally ignorant of astronomy ... and arrogant, refusing to listen,

Do I think that we'll have some systems in place to deal with the problem
of asteroid collisions? Yes, certainly. I just see more than just the
technical problems in setting up such systems. But they will come. And
while I too would like them sooner, I think that we'll probably not have
to deal with the problem for long enough that we can get together the
required system. 

So that's why I think 75 years is a better estimate than 25 years. And if
the required system is set up in 25 years, I'll be one of the first to

			Best and long long life,

				Thomas Donaldson

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