Re: Possible spacecraft weapons systems.

On Aug 26, 5:10 pm, atomicthumbs <atomicthu...@xxxxxxxxx> wrote:
I've decided to compose a list of weapons systems for spacecraft (present
and future). For this, let's assume a spacecraft with a zero-point energy
system and an entropy-reduction cooling system that runs on magic. The
list is as follows:

Okay, but if you've got such magical power and heat rejection systems,
then it would seem a little funny to not have magical weapon systems
also.

Masers - like lasers, but they shoot microwaves.

Pretty much useless for anything other than communications and active
sensors. Even for point blank range CIWS, where the beam spread
isn't a blatant deal-killer, microwaves simply bounce off conductive
hulls too efficiently to make for a plausible weapon system. Better
to
deliver that energy in the form of a laser or particle beam which
won't
just bounce off.

Lasers - the classic weapon. Fires a beam of light, anywhere from low
infrared to x-rays.

There are all sorts of different lasers. The ones I favor are pulsed
free electron lasers using a lasership and a distant fresnel or zone
plate lens (possibly using something I call "harmonic armor" to help
protect the rather large lens from enemy far). Unlike typical laser
weapon concepts, this can reach very long ranges and can scale
up to great power levels. Most laser weapon concepts are limited
by the power levels that the optics can handle. By using a distant
but large fresnel or zone plate lens, the only optics involved are a
large lens which focuses the beam onto a small spot on the target.

Useful for intense heating, burning, and cutting of
substances.

I tend to favor pulsed lasers over continuous lasers. A continuous
laser more or less has to melt its way through a target, which
requires a lot more energy than riddling the target with shrapnel.
But a laser is made up of photons, so it can't directly provide
shrapnel. The solution is to use a pulsed laser, which can vaporize
a small amount of the target to produce an explosion which
converts other bits of the target into shrapnel.

The ideal thing is to create an explosion inside the target, because
a surface explosion directs most of its energy in the direction of
least resistance--out into the vacuum of space. On way to achieve
this desired effect is a train of pulses. First, a few small "drill"
pulses to blast out a tunnel, and then a big "blast" pulse to create
an internal explosion.

Another way is to fire a hard X-ray laser which is very penetrative
to begin with. The zone plate free electron laser weapon design
can scale up to gamma rays, in principle.

X-ray lasers can make things explode due to very
intense heating and other effects.
These would also penetrate and give any
human inside the spacecraft cancer or serious death.

I suppose you're thinking of nuclear bomb pumped X-ray lasers.
But they might not even work, and even if they did work, they
aren't nearly as powerful as you're thinking. The idea was that
they'd produce radiation damage knocking out the electronics
of Soviet ICBM warheads. However, ICBM warheads are
small and can't afford the sheer mass penalty of any sort of
radiation shielding. A manned space warship would either
have heavy radiation shielding or future cancer treatments
would render such radiation shielding unnecessary. Either
way, a nuclear bomb pumped X-ray laser is not a threat to
the human occupants.

Electrical beam - an oft-overlooked weapon. Put a high enough charge into
a needle facing into a vacuum, and you'll get a stream of high-speed
electrons ready to create a current in whatever conductive surface they
hit. Can be negated by a plastic spaceship.

Electron beams are too hard to aim for anything but point
blank range use (they get deflected by natural magnetic
fields).

Even at point blank range, they won't do damage the way
you're thinking. An incoming missile might not have any
magnetic field (not worth it), but it probably has a conductive
hull of some sort. This will act like a Faraday cage, preventing
any "lightning bolt" of electrons from damaging what's inside.
The reason lightning bolts can be so damaging is because
they actually travel through a victim on their way to the ground.
But there's no "ground" behind a missile in space. The
electrons will hit the Faraday cage and then have no particular
reason to flow anywhere inside.

However, a high velocity electron beam can do a LOT of
damage simply by pumping sheer kinetic energy into the
target. The charge of the electron is mostly irrelevant,
except insofar as it turns the atoms of the target into big
gap-less "nets" that catch the electrons pronto. (This
contrasts with neutrons, which see atoms as empty space
except for a tiny obstacle in the center.) The relevant
factor is that a high velocity electron has lots of kinetic
energy, and when an electron bumps into the target, this
kinetic energy gets absorbed by the target.

A free electron laser weapon can have an auxiliary CIWS
mode which directly blasts the target with the electron
beam. This can be VERY powerful. A free electron laser's
peak power level is limited by the fact that only a fraction of
the electrons will lase on a given pass through the electron
wiggler. By recycling the electrons, the kinetic energy of
the electrons that don't lase isn't wasted--the electrons
loop through the weapon until they lase. But this does mean
the pulse of energy is "smeared out" a bit. In contrast,
by using the electron beam directly, the entire pulse can
hit the target all at once.

One potentially useful thing about an electron beam is that
it can be slewed through wide angles electronically. A
CRT monitor or TV uses this principle. This might be
important for CIWS where the weapon needs to engage
many submunitions simultaneously from many directions.

Particle beam - Basically a more powerful version of your average linear
accelerator. Neutrons would cause radiation burns, DNA mutations, and
death to the people inside the spacecraft as well as inducing
radioactivity. Not sure about protons or more exotic particles.

It's not actually clear if it's even possible to make a neutron
beam weapon. Currently, all particle accelerator designs
use electromagnetic forces and those forces have no effect
on neutrons. Even if you did figure out how to make a high
energy neutron beam, it's not clear how useful it would be
as a weapon since so many neutrons might simply sail through
the target unhindered.

However, a neutral particle beam of atoms is certainly possible.
The idea is to accelerate ions and then neutralize them after
they've been accelerated. There are a lot of HARD to solve
problems with taking a neutral atom beam and focusing it at
useful combat ranges, but there's no obvious hard physics
reason why they can't be competitive with lasers.

Atom/molecular/ion beam - Like a particle beam, except uses more massive
"particles" for more damage. Ion beam would have electrical effects due to
positive/negative charge. More difficult to implement.

Actually, an atom or ion beam is typically called a "particle beam".
The aren't more difficult to implement than the other sorts of
particle beam (electron beam, proton beam, positron beam,
anti-proton beam). The hardware is actually exactly the same,
except the strengths of the fields may be different to account
for the different charge/mass ratio of the ionic particles.

As for "more massive"...not really. For various reasons, the
best atom to use is hydrogen. A hydrogen particle is hardly
any more massive than a proton. And even if you do use a
heavier atom, the extra mass doesn't do any more damage.
In all cases, the overall amount of kinetic energy pumped
into the target is the same, and the target effects are the
same. Whether the beam is charged or not has no significant
impact on the target effect.

Now, implementing a "molecule" beam would indeed be more
difficult. Current particle accelerator designs don't really
work well with molecules since molecules can't be molecules
if you strip away too many electrons and you thus can't have
a really good charge/mass ratio. Also, a molecule isn't
heavier enough to make any difference to the target effect.

That said, I have in the past pondered a "colloid beam", which
fires dust particles big enough to actually pit and abrade the
target rather than just pour kinetic energy in an evenly
spread particle stream. The numbers didn't really work out.

Energy beam - Think Star Trek phaser. This beam uses an undiscovered form
of energy to create damage, disintegration, matter-to-energy conversion,
collapsing matter into a black hole, or any number of other possible
effects, depending on what the energy does.

Well...here's the magical weapon. Pretty much anything is
conceivable.

Missiles - your standard guided missile can be loaded with a variety of
warheads, and use a variety of targeting systems, including thermal,
optical, radar, gravimetric sensing, and possibly others.

There is a wide variety of types of missile. I tend to favor external
guidance due to the superior precision, and external power because
it's perhaps the only way to combine high delta-v and high thrust.
A missile can be literally as simple as a solid cannonball. The
guiding
warship uses pulse lasers to vaporize a bit of the cannonball. The
expanding gas produces thrust in the opposite direction.

Thermonuclear warhead - Your standard fusion bomb. These can produce
large amounts of damage to unshielded spaceships, but also produce a large
explosion, large amounts of ionizing radiation, lots of heat, and (if used
in atmosphere) an electromagnetic pulse. These are also heavy.

Nukes can do a lot of damage to a close target. I'm not sure what
you're thinking is supposed to be a "large explosion", but nukes in
space aren't like nukes in an atmosphere. You can think of a nuke
in space as a flashbulb emitting a powerful pulse of soft X-rays,
neutrons, and a small puff of plasma. As far as the target is
concerned, it's the X-rays and neutrons which are the problem.
The X-rays will cause a surface explosion of vaporized hull, while
the neutrons will cause massive radiation damage. The explosion
from the vaporized hull will be much larger and more visible than
the small puff of plasma from the former missile.

Most of the nuke's actual energy is in the expanding shell of
X-rays and particles which didn't directly hit the ship, but these
aren't very visible.

Conventional explosive warhead - Your standard high explosive. These
could be good for fighter combat, or lots of them against a larger craft.

The best sort of explosive warhead is a fragmentation warhead.
At plausible space combat speeds, the kinetic energy of the
missile is far greater than the amount of energy an explosive
warhead could add. Therefore, you should devote most of
warhead mass to shrapnel and only use a small explosive to
spread fragments.

Antimatter warhead - These are very powerful.

Theoretically, it's possible--but you need good mixing in order to
get a good yield. Also, most of the energy is released in the
form of gamma rays which can sail through a target. Depending
on the target, a fission-fusion-fission nuke could do more damage.
A nuke might only produce a fraction of the energy, but soft
X-rays and slow neutrons don't overpenetrate.

I should note that antimatter warheads are pretty close to "magical".
It's fantastically expensive to produce antimatter. An antimatter
catalyzed nuke may be a far more practical warhead--possibly
being smaller than a normal nuke.

Sand - Useful for mounting on fighters, and able to destroy almost any
unshielded spacecraft. At orbital/interstellar speeds, a couple thousand
grains of sand would be very easy to launch from any sort of spaceship,
and would do massive damage do to high velocities. These aren't very
dramatic, though.

Actually, no. At interstellar speeds, you've got a severe problem of
targeting a target--you MIGHT be able to see the target before you
pass him up, but good luck performing the stupendous sideways
thrusts required to get the Sand on an intercept course!

At orbital/interplanetary speeds, sand just isn't all that impressive.
A grain of sand does very little damage, actually, and at any sort
of plausible space combat ranges you'll be lucky to get even a single
grain of sand to hit the target.

Mass drivers - These could take the form of railguns or coilguns. They
could launch a metal slug, or a missile designed to survive the high
launch speeds, and magnetic flux or current. Does high amounts of damage.

You'd only ever want to shoot an unguided slug at an incoming
missile for CIWS. You don't actually need a high muzzle velocity,
since most of the kinetic energy of the impact comes from the
incoming. For any sort of offensive use, you need a guided missile.
Now, a dumb metal slug actually can be guided, using an ablative
laser approach. But missiles with integral thrusters are good
because you can launch masses of them at ridiculously high rates
of fire. All of these cheap little bastards can be simultaneously
guided by the same external guidance instructions and/or beams.

In any case, mass drivers seem to suffer from slow muzzle velocity.
It takes the better part of an hour for a 100km/s projectile to cross
a light second, and that might be an order of magnitude faster than
what a reasonable mass launcher can achieve.

Ramming - Not to be overlooked. Spaceships can run into other spaceships,
destroying them both unless one is a specialized ramming ship with
powerful engines and extra frontal armor.

Any spacecraft can be turned into a makeshift missile. But it
requires
magic tech to survive an impact with a similarly sized spacecraft.

If you can think of any more, add them to this list!

One unusual weapon concept I once came up with was a "positronium
gamma beam"--which is worth mentioning even if just for the cool
name. Basically, you use a linac to accelerate electrons and
positrons
up to high energies. Aim these beams at a close target, and most of
the energy ends up in hard gamma rays concentrated in a somewhat
narrow cone. The electrons and positrons may temporarily form
positronium; which decays into photons.

If you add in some magic technobabble, then positronium can lase
(this is really magic--positronium decay doesn't seem to offer any
possible mechanism for lasing). If positronium could lase, then the
narrow stream of positronium could form a VERY long range SASE
laser.

Another weapon system which deserves mention is the laser drone.
This is a drone which takes an externally provided laser and aims it
at a target. Traditionally, this is thought of as using a mirror to
redirect the beam--most famously as an SDI concept for using a
ground based laser along with orbital mirrors to shoot over the
horizon. But I prefer a swarm of small diffraction drones, which
form up into patterns to diffract the beam. Zone plate diffraction
reduces the beam strength by 50%, but unlike mirrors they work
with the short wavelengths required for long range effectiveness.

Zone plate laser drones are among the few weapon systems
potentially useful for interstellar warfare. Light speed delays
mean that some sort of "terminal guidance" is absolutely
necessary no matter what weapon system is used. But relativistic
missiles can't change course rapidly enough to turn and hit the
targets. Laser drones don't need to change course--they just
adjust the diffraction pattern slightly to alter the angle of the
beam.

Isaac Kuo

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