From: rwallace@unix1.tcd.ie (russell wallace)
Newsgroups: rec.arts.sf.science
Subject: Re: Wreaking a habitat (was Re: Wrecking a Planet
Date: 13 Jan 93 01:02:40 GMT
Organization: Trinity College, Dublin

In <1993Jan12.041012.3461@Princeton.EDU> jdunning@phoenix.Princeton.EDU (John Alan Dunning) writes:

>Why do you insist on making the planetary space-based defenses so
>expensive to build and maintain?  Any civilization capable of mounting
>significant orbital defenses is going to build them in orbit, not
>planetside.  Of course that means there would have to be one or more
>habitats nearby to build and maintain the weapons,

Right, then the population of the planet are not defending themselves
unaided, instead they're being defended by the people of the
habitats/moon bases/asteroid bases. But, the space population are going
to find it more expensive to defend a (large, totally immobile) planet
than a (small, somewhat mobile) habitat.

>Also, it sounds like everyone is assuming the civilization will be
>based on either a single planet or on multiple habitats.  You're not
>going to have habitats without a planet, unless you're colonists from
>another system and didn't find any habitable planets in this one (then
>why did you come?), or the home planet was rendered mostly
>uninhabitable by some nuclear conflagration, or you've turned it into a
>giant zoo in some sweeping environmental reform.  You're also not
>going to have a planet with orbital defenses without habitats,
>precisely because, as Mr. Wallace notes, it's just too expensive.

Yes, a planet can't fight a space war without a population and industry
base in space. On the other hand, you could have habitats colonizing a
nearby star system with no habitable planets (which there probably would
not be; life is needed to make a potentially habitable planet actually
habitable, by photosynthesis etc. - unless you think that most star
systems have life). Why did you come? To colonize the star system by
building more space habitats, of course :-).

>One of the advantages habitat-supporters claim is that the colonies
>can be anywhere in the system that they want and can move around at
>will, to confound long-range, unguided ballistic weapons.  But is this
>likely?  What are all these habitats doing out there?  How are they
>making money?  

They grow their own food, have manufacturing industry based on materials
mined from asteroids, comets and moons, and trade manufactured goods
and services among themselves and with planet-dwellers.


>The cheapest way to ship (inanimate) products between colonies and 
>near-earth obrit would be to use some sort of mass driver to simply launch
>the unguided or minimally-guided cargo ships at a big receiving
>station of some sort right next to the colony.  (This was how O'Neill
>proposed getting ore from the moon to orbit cheaply.)  This system
>assumes, of course, that the orbits of the habitats are predictable.
>Shipping cargo to randomly jinking habitats is going to be much more expensive.

You can't launch cargo from Earth with a mass driver. And the habitat
will only have moved a couple of hundred kilometres by the time your
cargo arrives => easily retrived by a tug.

>Perhaps the economy is based mainly on the trading of information,
>rather than physical products.  In that case the colonies might indeed
>be anywhere.  But their distance from each other would still be
>limited by the speed of light.  If the consumers are used to the
>near-instantaneous access to information available from a planetwide
>network, they'd get pretty impatient if they have to wait 5 or 10
>hours to get the information they just purchased.  Again, the economy
>would dictate that that the habitats would be clustered around the
>home planet or at least clustered around each other, providing
>attackers a larger target.

If they're hundreds of kilometres apart, this makes life much *more*
difficult for an attacker; a shotgun attack is still going to hit mostly
empty space, and the habitats can cover each other with their defensive
armament. But I don't see why the habitats couldn't be scattered around
the solar system, particularly since different mineral resources are
available in different places (heavy elements in the asteroid belt,
light elements further out). So what if you have to wait an extra couple
of hours for the computer program or video you've just purchased?

>>>And without postulating a technology which would also allow the rock to
>>>home in on your habitat, the habitat couldn't dodge.  Use the same engines.
>>>And it would be cheap - no need for life support or a lot of the other things
>>>needed on a habitat. Face it - a nice place to live is seldom a nice place to
>>>fight from - and vica-verse.
>>
>>If the rock is small, the defensive armament will vaporize it. If it is
>>big (which I think you are assuming it to be), the cost of tossing it
>>around at those sort of speeds, plus mounting enough defensive armament
>>on it to prevent the habitat from launching missiles to destroy it (or
>>at least disable its engines), plus the accomodation for the personnel
>>to operate and maintain all this equipment, will make it cost a good
>>fraction of what the habitat itself cost. Plus, it will be seen coming
>>from a long way off, leaving plenty of time for the defenders to do
>>something about it, or at least evacuate the habitat, leaving you with
>>a trade of a very expensive set of engines, armament and life support
>>system, for a very expensive habitat. Not much point, methinks.

>This assumes that the inhabitants have somewhere to evacuate to.  The
>cost of the "life boats" is also a factor in the placement of the
>habitat.  You can make fairly cheap, and therefore pretty
>uncomfortable, life boats if you can expect rescue within 24 hours,
>say.  Maybe giant beach balls with an air supply and minimal food.  If
>rescue times are measured in weeks or months, you're looking at
>well-stocked ships, with plent of radiation shielding, food, etc.  So
>the cheaper the life boat, the closer the habitats, and thus the
>bigger the target.  "Bigger" in the sense that the attacker can more
>confidently assume that the habitats in the cluster won't be moving
>very far from each other, because the inhabitants want to take
>advantage of the benefits of having close neighbors: cheap shipping,
>more customers, faster rescues, etc.

It seems likely that habitats will occur in clusters, for trade, mutual
defense in times of war etc. (See my above argument for why a cluster of
habitats a few hundred km apart is harder to attack.) So rescue would be
pretty soon.

>In fact, disrupting trade may be all you need to do to take over the
>system or destroy its civilization.  If the habitats are clustered
>together, throw rocks at them until they disperse and start jinking.
>Everything is suddenly more expensive, and the habitats inhabitants
>can no longer rely on a speedy rescue if they need to evacuate.  Each
>of the habitats now has to make its own spare parts, or do without.
>Pretty soon people are feeling kind of lonely and isolated.

No, they're still only a few hundred kilometres apart.

--
"To summarize the summary of the summary: people are a problem"
Russell Wallace, Trinity College, Dublin
rwallace@unix1.tcd.ie
Xref: sparky rec.arts.sf.science:3917 alt.folklore.science:4547