From: curt@quest.UUCP (Curtis Gibson)
Subject: Re: Wrecking a Planet (Was: Re: Sci-Fantasy Weapons)
Organization: Quest Research, Inc.
Date: Wed, 06 Jan 1993 20:33:01 GMT

>>curt%quest.UUCP@cs.umn.edu (Curtis S. Gibson) First posted
>>Build a linear accelerator catapult out in the ort cloud, well out
>>side the enemy detector range.  About 5 light days or more I'm guessing.
>>We reduce the chance of detection by hiding next to a comet, we also
>>use the comet for raw materials and reaction mass.  The catapult would
>>be hundreds of kilometers long, maybe over a thousand if need be.  We
>
>bscott@nyx.cs.du.edu (Ben Scott) Replied:
>Problem 1 - what kind of accelerator?  Unless the projectiles are metallic
>in the extreme (which Oort cloud objects, hypothetically, aren't), you'd
>need to figure out some kind of magic tractor-beam thingie to accelerate an
>uncharged object.  Well, one SF author said something about dumping
>electrons (from an ion drive) into an object for a few months to develop a
>static charge; but I doubt this would work since even a vacuum allows a
>charge to dissipate.

Well without inventing the "Magic Tractor-Beam Thingie", I expecting
the Mag-Lev Train tech will work just fine with a bit of upscaling.
(Mag-Lev is the linear electric moter that the Japanese & Germans are
years ahead of us Americans developing into a High Speed Train.)
I would build the catapult in sections back in my home system or a
system I controled.  Break it down, transport it, set up and launch,
and do it quickly, before they spot you doing it.

>
>>would use hundreds, maybe thousands, of 1 to 100 ton projectiles.
>>The projectiles would be solid iron, chilled down to near 0 Kelvin to
>
>Yeah, but again, where do you get the iron in the rock and ice asteroids?
>The only metallic objects we've seen so far come from the asteroid belt;
>hence the theory that the belt was originally a planet and had a metallic
>core like Earth.  The Oort cloud is further out and like the further
>planets, consists mostly of the lighter elements.  Jupiter, for example, is
>largely hydrogen and helium.

Bring it in from outside the ort cloud.  I don't plan on spending a
few years building the catapult right under their noses (or whatever
they have for that purpose 8^) ).

>
>>Some Points to ponder:
>>  What's the best mass for the projectiles?
>
>As much as possible.
>
>>  What's the best speed?
>
>As fast as possible.

These questions were supposed get you thinking about the Gee forces needed
to kick a projectile to .8 C in a distance of 1000 km.  I can't find
my old physic text books to get the formulas for acceleration, its been
twelve years and 6 or more moves sence I took intro to physic.  
Can we build a Mav-Lev style catault that could that the strain?  We
may have to settle for .4 C and 500 kg, but we get lots of shots.

>
>>  What will the best of the above yield in megatonnes?
>
>Quite a few.
>

One of the few formulas I still remember is the E=1/2MV^2 .  And I know
that it only holds for non-relativistic velocitys.  Above some value of
< C its a different formula.  Whats that velocity and formula?

>>  What's the minimum number of projectiles needed to wreck the ecosphere?
>
>About one.  If it's a good 'un.
>
>>  What's the best spacing in the "footprint of destruction"?
>
>Depends.  On a LOT of things.  Whether you want to hit water or land, which
>in turn will depend on what you want to do and how quick.  How many you have
>to work with will matter of course.
>
>>  Can a projectile travelling .8 C, fired from 5 light days out in the
>>    ort cloud, be aimed accurately to hit a planet 1 AU from the star?
>
>Nothing scientific forbids it; a formidable technical challenge, to be sure,
>but so is the rest of your idea...
>
>>  Will we need to make midcourse corrections?
>
>Depends on how one solves your previous question.
>
>>  Will we be able to make midcourse corrections?
>
>Depends on how you get it moving in the first place, I'd guess..
>
>>  Will we be able to make midcourse corrections and still maintain
>>    stealth?
>
>Depends on how you solve your previous problem...
>
>>  What could stop the projectiles? (or make miss the planet)
>
>An obstacle.  The usual idea of a bunch of H bombs fired toward it would be
>a good start.  But how to hit something going at .8c?  By the time you
>detect it you're nearly too late.
>

After I sent off my first posting I thought that sand or gravel spread
in the path of the projectiles would be a good defense.  The blast of
hitting a big grain of sand or small gravel at .8 C would slow the
projectile a tiny bit.  But do it far enough away, 8 or 9 AUs and you
got a clean miss.  I don't think any misses will be orbiting back to
be a problem next year 8^).

>>  Would the projectiles be detectable by their wake in the solar wind?
>>    If so how far away?
>
>Probably not; you'd have to have sensors behind it.  You don't see the
>"wind" from the side.
>
>>  Would using fusionable materials (2H)(is that the correct notation?)
>>    improve the destruction enough the justify the effort?
>
>Not sure I understand you here.  You're suggesting hitting a planet with a
>ball of hydrogen instead of a ball of iron?

Yes, deuterium or tritium.  At the energy levels its going to hit at, it
should undergo fusion with no problems.  Look Ma, fusion without fission.
The question is, will the fusion provide enough energy to matter in 
the huge amount just the speed will liberate?

>
>>  Would using fusionable materials make it (easier/harder) to stealth
>>    the projectiles?
>
>Since you don't specify the "stealth" method, nor what detection strategies
>the "stealth" countermeasures are designed to thwart, it's a bit tricky to
>answer that one.

Stealth in every way possible, light for optical searches & lider
(spell???), radio wave lengths for radar, infa-red, ultraviolet,
even x-rays and gamma if we can.  We don't want them to see the
projectiles at all, no clue as to why the place is blowing up around
their ears (or what ever they use for that 8^) ).

> 
>>This is the mad ranting of a former mad rocket scientist at my former
>>Jr High.  And have been submitted for entertainment purposes only.
>>And are in the public domain.  And hoping someone with a scientific
>>education, (mine's in business) will work out the answers.  And I 
>
>Not a bad question; it's just that speculation about scientific questions
>without any scientific backing makes it rather easy to miss some rather
>important points.  More of a fun exercise (if it's fun) rather than anything
>that will accomplish results.    
>
>One thing to remember is that the damage depends on kinetic energy - and you
>can increase kinetic energy (or whallop, in business terminology...) by
>increasing EITHER mass or velocity.  But kinetic energy increases as the
>SQUARE of velocity, and only linearly with mass.  So a small object going
>REAL fast will do the trick as well as a larger object moving more slowly.
>

Curtis S. Gibson    curt%quest.UUCP@cs.umn.edu
Newsgroups: rec.arts.sf.science