From: travis@cco.caltech.edu (Leopold E. Travis)
Subject: Re: Star Wars vs. Star Trek, tech & tactics, etc.
Organization: California Institute of Technology, Pasadena
Date: Sat, 25 Jul 1992 22:51:46 GMT

rlbell@babbage.waterloo.edu (Richard Bell) writes:

>In article <1992Jul24.103955.8494@cs.ruu.nl> mmhazewi@cs.ruu.nl (Maarten Hazewinkel) writes:

>>As for the DS2 shield, this was apparently of an extraordinary powerful
>>variety, requiring planet (moon) based machinery. The DS2 might eventually
>>have gotten an equivalent shielding power, if it had been completed.
>>
>>And to be ahead of some people, who are bound to ask: why didn't the DS1 have
>>these powerful shields? Well, there are a number of possibilities.
>>
>>1. They didn't have these new shields then, they were only invented when the
>>DS2 was built.

>We saw one on Hoth, it must be a cooling problem, waste heat rejection is
>a severe problem for spacecraft, the shape of the Death Star, minimum surface
>area for its volume, makes it even worse.  A planetary atmosphere carries
>the heat away by convection, and then the entire planet's surface is available
>as a black body radiator.  The Death Star is a HUGE spacecraft, but it is an
>extremely tiny planet.  

The Death Star must have incredibly efficient cooling capabilities,
considering that it channels a hundred thousand times the output of
the sun when it fires its planet-destroying weapon.  A more likely
explanation for the moon-based generator is that it was required to
make the plot work.  After all, it would have been more prudent for
the Empire to complete the second Death Star's shield generators before
working on its offensive capabilities.  But then the Rebellion would
have lost...

Returning to the Star Wars vs. Star Trek idea, consider the following
scenario:  The Death Star drops out of hyperspace near a Federation
world, accompanied by fifty to a hundred Star Destroyers, and begins
powering up its 100-quadrillion-megaton planet-zapping weapon of doom.
Can the Feds stop it in time?

Clearly if it has a shield like the one provided by the moon-based
generator, the answer is no.  It wouldn't even need the Star Destroyers;
it could just laugh at the Feds' attacks, blow up the world, and hop
back into hyperspace.  

So let's suppose it doesn't (perhaps this new shield technology _was_
invented after the first Death Star was destroyed, or whatever).  The
Feds can clearly toast the Star Destroyers--which can't fight at FTL
speeds--but they may buy the Death Star some time.  So the question
becomes, how many photon torpedoes would be required to destroy the
Death Star?

I don't know if there's an official figure for the yield of a photon
torpedo; if so, I'm sure someone will post it.  Let's assume for the
moment that it's about 100 megatons.  Now a 100-megaton surface burst
on dry soil will carve out a crater about 1.2 kilometers in diameter,
and 0.3 kilometers deep (source: Glasstone and Dolan's _The Effects of
Nuclear Weapons_).  The Death Star's made of metal, but it's mostly
hollow, so suppose as a rough estimate that a photon torpedo will
obliterate a portion of this diameter and depth.  It seems likely that
an area of at least twice this diameter will be rendered non-functional
from shock and heat effects, so a photon torpedo effectively destroys
about 4.5 square kilometers of the Death Star's surface.  The area of
the Death Star being about 45000 square kilometers, this means about
10000 photon torpedoes would be required to destroy its entire surface.

Of course, one probably wouldn't have to destroy the entire surface
area to make it unable to fire its gun.  Even so, it seems likely that
the Death Star could withstand many hundreds of photon torpedoes without
flinching.  So it looks like there's no way for the Feds to prevent it
from destroying the planet and then escaping back into hyperspace, since
only a few minutes at most are required for it to do this (it took half
an hour at the moon of Yavin because Yavin itself was in the way and
the Death Star had to maneuver into position).

The above analysis is by no means rigorous; comments and refinements 
are welcome.

--
Leopold Travis
travis@alumni.caltech.edu

Newsgroups: rec.arts.sf.starwars