----- Original Message -----
From: "Robert J. Bradbury" <[EMAIL PROTECTED]>
To: "Europa Icepick" <[EMAIL PROTECTED]>
Sent: Monday, October 08, 2001 1:09 PM
Subject: Re: More jolly Space Station news
>
>
> On Mon, 8 Oct 2001, Bruce Moomaw wrote:
>
> > Forgive me for saying so, but you have a complete bee in your bonnet on
the
> > urgency of asteroid deflection.
>
> Bruce, it is precisely because I understand the laws of statistics
> that I have such a bee. I have sat at the roulette tables in Las
> Vegas attempting to play the odds and lost. It is precisely because
> you cannot guarantee that the heavy hitter against civilization will
> come in 10 million years vs. tomorrow that I argue that attention is
> required. The fundamental question is this -- How much would you be
> willing to pay such that you are alive tomorrow?
>
> > It will be tens of millions of years before another dinosaur-killer
asteroid
> > hits Earth -- and by that time, humanity will either be spread all over
the
> > Solar System or (more probably) will have totally exterminated itself,
even
> > if we expand into space at only a very slow trickle.
>
> You *CANNOT* guarantee with 100% probability that a dinosaur-killer
> asteroid will not strike the Earth tomorrow. You are simply hoping
> that the statistical probabilities are in your favor such that you
> have 10 million years before such an event. Are you willing to bet
> humanity on such odds? More importantly -- can you convince me that
> *I* should bet humanity on such odds.
Actually, what I'm "betting on" is the quite elementary statistical concept
of "expected value" (which, by the way, is the reason I've never gambled).
David Morrison has estimated that the chance of the average human being
killed by an asteroid impact is actually about the same as the chance he
will be killed by an aircraft accident (asteroid impacts, of course, are
tremendously rarer but are likely to kill tremendously more people). Thus,
it seems to make sense to spend about as much yearly on preventing one as
the other -- if such an expenditure has the same chance of preventing such
deaths.
But -- as I've said before -- the overwhelming number of impacts will be
Tunguska-type events, and even they will occur on the average only once
every several hundred years. And, with sufficient advance warning, we can
get out of their way; strictly speaking, we don't even need to deflect them
(although it may often be worth our while to do so). Dinosaur-killer rocks,
which absolutely must be deflected, come along on an average of once several
tens of millions of years -- which means the odds are overwhelming that we
will have the technology to routinely deflect them by the time the next one
arrives, even if we spend almost NOTHING yearly on space exploration and
industrialization. If we're going to talk about "betting humanity on such
odds", I can't guarantee that an armada of hostile alien spaceships won't
arrive at some point and wipe us out, either -- but I don't see you (or
anyone else, except perhaps Mulder and Scully) arguing that we should spend
billions yearly against THAT particular super-extreme longshot.
> > The only significant short-term risk from an impact is that
> > another Tunguska-size event might panic a nation into thinking it was
under
> > nuclear attack -- and that (along with the need for evacuation of the
small
> > impact area), is why a Spacewatch network is cost-justifiable, but your
> > proposed huge project is not.
>
> Why? I'll note that the U.S. is planning to spend between $15 -$100
BILLION
> on the loss of ~5000 individuals. This is equal to an ~2-5 year NASA
budget
> allocation. Go compute the frequency of impact likely to wipe out 5000
> people -- Is NASA spending $1-$5 billion a year on preventing that?
The purpose of this military operation, obviously, isn't just to save "5000
individuals" -- it's to minimize the chances of much greater losses in the
future, since bin Laden and his damned swollen organization will certainly
switch to using nuclear and biological weapons the moment they can get their
hands on them. The purpose is to destroy Al-Quaida -- or as much of it as
possible -- before it can do so.
> > (Moreover, if we ever do decide to deflect an asteroid or comet, we
could
> > do it right now -- without any need for a major manned presence in space
> > -- just by aiming unmanned vehicles at the object.)
>
> Bruce, if you really believe this, you need to review the literature
further.
> Have we identified the targets, do we have the vehicles, can we accelerate
them
> towards and intercept the objects with sufficient kinetic energy, etc.,
etc.
>
> I do not believe that is the case. I would further argue that our current
> knowledge with regard to potential hazards is so insufficient that even
> if we did have the capability of deflecting them we do not know their
> whereabouts and trajectories sufficiently to use such capabilities
effectively.
True -- but the point is that a space station, of ANY type, is completely
irrelevant to doing this. Accurately locating NEOs, and launching and
controlling warheads to deflect them (even the biggest ones), can be done
just as cheaply from Earth. And we certainly don't need to "brake NEOs into
Earth orbit and mine them" for that purpose.
==
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