From: rwallace@unix1.tcd.ie (russell wallace)
Subject: Re: Wrecking a Planet (Was: Re: Sci-Fantasy Weapons)
Organization: Trinity College, Dublin
Date: Wed, 6 Jan 1993 19:24:46 GMT

In <1993Jan6.145739.25169@mail.cornell.edu> phydeaux@guru.med.cornell.edu (Dave Weingart) writes:

>In article <rwallace.726282358@unix1.tcd.ie>, rwallace@unix1.tcd.ie (russell wallace) writes:
>|> stop a smaller fraction of the bombs. This is one reason for living in a
>|> space habitat rather than on a planet; a space habitat is a *lot* easier
>|> to defend.

>On the other hand, the consequences of even _1_ breakthrough by the attacking forces
>are much more severe.

Sure, a 0.5-gigaton bomb (incidentally I got my calculations slightly
wrong about the weight/yield ratio of bombs in my original message - a
0.5-gigaton device will weigh about 10 tons) will probably totally
destroy a space habitat if it gets a direct hit. (It will have to get a
*direct* hit on a relatively small target, as opposed to being abl to do
damage exploding anywhere in a planetary biosphere.) Even then, there
will probably be survivors in sealed compartments who can be rescued
later. But a population of say 10 billion will be scattered over *many*
space habitats rather than all on a single planet, so even if many hits
are scored, a lot of the population will still be safe.

Most importantly however, is that a space habitat can move. Not with
great agility, to be sure, but it means that a guided, powered missile
is needed, not simply throwing bombs on a precalculated ballistic
trajectory. Much more difficult, and you can't use simple inflated
balloons as decoys with the projectiles. Also a bomb to hit a habitat
will have to come within range of the habitat's own defensive armament,
which can be of almost any desired size and power output, with the
habitat's full power generating capacity available, and almost unlimited
heat sink capacity, and the population on hand to maintain it. As
opposed to trying to defend a planet; the defences have to be in orbit,
which means they're separated from the population and industrial plants
which are on the ground.

>Can't recall the story I read some years back (series that ran in Analog, about the
>captain of various freighters (Shuster?) who eventually ends up in the company's space
>operation), when talking about why the space base should be on the Moon rather than in orbit
>(the quote is not exact):

>"It can't be shot down.  Over my dead body is the company gonna invest my hard-earned
>money in a billion dollar clay pigeon."

Huh? A base on the Moon *can't move*. It's a sitting target. You can
throw unguided bombs from 10 AU away and hit it precisely. Or you can
sneak up on it around the horizon. It's dramatically better than a
planet (no atmosphere to conduct shock waves and fallout, and ruin the
performance of ground-based weapons), but it's certainly not as good as
a space habitat. Also, 10 billion people living on the Moon would be
confined to a small area, compared to 10 billion people living in (say)
the asteroid belt, so a shotgun attack approach might be feasible.

--
"To summarize the summary of the summary: people are a problem"
Russell Wallace, Trinity College, Dublin
rwallace@unix1.tcd.ie