From: rwallace@unix1.tcd.ie (russell wallace)
Subject: Re: Wrecking a Planet (Was: Re: Sci-Fantasy Weapons)
Organization: Trinity College, Dublin
Date: Fri, 8 Jan 1993 00:19:35 GMT

In <1993Jan7.173125.20305@linus.mitre.org> m23364@mwunix (James Meritt) writes:

>In article <rwallace.726348286@unix1.tcd.ie> rwallace@unix1.tcd.ie (russell wallace) writes:
>}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.

>Why bother with total destruction?  Have you considered the results of a
>number of 5 inch holes drilled through it by very fast gravel?

As I explained in another article, a piece of gravel is not at all going
to drill a hole in a 1 billion ton O'Neill habitat. Even if it did, the
population presumably have sealed compartments to get into during raids.
Plus, your attack carrier will have to get reasonably close to throw the
gravel. Probably within range of the defensive armament, plus the
defenders will have interceptors, as well as lots of civilian ships that
can be armed and used as interceptors.

>}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. 
>Unless you are advocating near continuous random changes in acceleration,
>it fits in much the same category as "planet" - except that the attack
>could come from any location in the universe, as opposed to less than
>half for a "moonbase".  There is something reassuring about being able to
>have your back against a few thousand miles of protective rock...

Presumably the attackers of a planet will have the wit to time their
attack to hit the right side of the planet.

>}Also a bomb to hit a habitat
>}will have to come within range of the habitat's own defensive armament,

>So?  Tough to stop a rock...

The habitat's defensive armament (which can be of almost any desired
size and power output) can simply vaporize the rock a long way away.

>}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

>heat sink, yes.  But terribly vulnerable radiators.  So to zap it, dump silver
>paint so that it coats the radiator.  And as for the "full power
>generating capacity", if it is environmental, you couldn't accelerate
>(read "move") and it could be closed down with black paint.  And if it
>is internal, so could the planetary base.  

Who mentioned radiators? The heat sink for a fusion gun or whatever
could simply be the habitat's water reservoir. I think a 10,000-ton
water storage takn could soak up quite a lot of heat (with bleeder
valves in case the water got too hot).

>}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.

>Only if you are trying to defend the planet, and not just the "special"
>site.  Most folks I know really wouldn't care if a few cubic miles of the moon
>get peppered by gravel.  There is a LOT of turf that would count as a "miss".

If an amount of nuclear explosives equivalent to a Dinosaur Killer hit
the Earth, that would cause a lot of inconvenience to everyone. Plus
that megatonnage aimed at say Europe would kill quite a lot of people.
Even not aimed at specific targets.

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