Re: Kicking a few ideas around in my head (SF), would like to get feedback

On Aug 6, 7:46 am, MatthewJRotondo <rotond...@xxxxxxxxx> wrote:

-Presume that a spaceship had some sort of insulation that would allow
it to control the amount of heat that it gives off, at the cost of
having to store it within the ship, to the point where it could store
ALL of its generated heat inside the ship for a limited time before it
melts the circuits and cooks the crew.
   1) is this theoretically possible, and
   2) if so, how fast would the heat build up? Is there a formula to
use? something that deals with heat generated and volume of    the
ship?

Consider that it takes about a megajoule to raise a kilogram of iron
from room temperature to its melting point and then melt it. A 10 ton
(10,000 kg) spacecraft made of iron with a 1 MW reactor would last
10,000 seconds before it melted, or less than 3 hours. In practice,
it would be disabled long before than by the rising temperature. The
spececraft described would need to be thrusting for significantly
longer than 3 hours to get a significant change in orbit for, say,
going from earth to mars.

-Weapons
--Besides chemical explosions, nuclear explosions, and the rather
implausible (in the conceivable future, anyway) antimatter torpedo, is
there anything else that can be used as an explosive? Besides using
the missile itself as a Kinetic bullet, of course. What would be the
best boom for buck for a space missile?

At 3 km/s, a projectile will impact with as much energy as its own
mass in high explosives. 3 km/s is quite slow for closing speeds in
space (expect around 5 to 10 km/s in earth orbit, 10 to 30 km/s in
interplanetary encounters). This makes chemical explosives both
redundant and pathetic. Unless you are going nuclear, a long-rod
penetrator of something dense (like tungsten) would probably be the
munition of choice. These would explode upon impact while also
defeating layered armor. You may want to read
http://www.projectrho.com/rocket/rocket3x.html#kinetic .

For nukes, the effects are a bit different from what you would expect
from detonations in atmosphere. You get a brief x-ray flash. If the
target is close enough to the nuke, the x-rays explosively heat the
surface and smash the target. You need to be fairly close for this to
work - in many cases, you get a better stand off kill distance by
releasing long rod kinetic penetrators. Nukes also release a lot of
neutron radiation, which may be lethal to biological organisms. You
may want to read http://www.projectrho.com/rocket/rocket3x.html#nuke .

--I'm not entirely clear on Lasers. My understanding (which may be
wrong) is that the more energy you pump into a laser, the stronger
said laser is. In that case, what would differentiate, say, an
infrared Laser from an X-ray Laser? In terms of energy consumption and
its potential as a weapon? What would be the most cost-effective type
of photon to use?

For lasers, you want two things. You want a lot of power (or energy)
in the beam, and you want it to focus well. A lot of people have this
misconception that lasers just go straight in perfectly collimated
beams. This is not so. Much like using a magnifying lens to focus
the rays of the sun onto a hapless ant, a laser will want to focus its
beam to as small a spot as it can on a target. This concentrates its
available power to a high intensity that can melt or burn the bad
guy. Clearly, the more you can focus, the higher your intensity, but
also the higher the power the higher your intensity.

Now, the shorter the wavelength of the beam, the tighter it can focus
for a given size of lens or focusing mirror. If you are restricted by
the size of your spacecraft to a 10 meter wide mirror, and you need a
10 cm wide spot or less to damage your enemy, a 10 micron far infrared
beam can be focused to damaging intensity at a distance of 83 km. If
you use a 1 micron wavelength near infrared laser, you have a range of
830 km. A 0.5 micron visible green beam would put the scorch into the
enemy at 1,660 km. And a 0.1 micron vacuum ultraviolet beam would
damage the other guy at a range of 8,300 km.

I see a number of people have gotten confused about the energy per
photon, and somehow thinking that the fact that an individual short
wavelength photon has more energy than an individual long wavelength
photon makes short wavelength beams more damaging. Nope. 1 megawatt
of long wavelength light focused into the same area as 1 megawatt of
short wavelength light will cause about the same effects.

Things get more complicated when you start going to the x-rays. X-
rays do not go through lenses and are not easily reflected by mirrors,
plus they penetrate some distance into the target so you need to
consider the depth of material heated. X-rays are very short
wavelength so they can focus very well, but the difficulty of getting
optical elements to focus them mitigates this to a significant degree.

You may want to read http://www.projectrho.com/rocket/rocket3x.html#laser
, http://www.panoptesv.com/SciFi/HeatRay.html , http://www.panoptesv.com/SciFi/Blaster.html
, http://www.panoptesv.com/SciFi/Focus.html , http://www.panoptesv.com/SciFi/Diffraction.html
, http://www.panoptesv.com/SciFi/DamageAverage.html , and
http://www.panoptesv.com/SciFi/DamageInstant.html .

--speaking of which, would a planet-based laser (say, mounted in a
really tall tower), which can draw energy from terrestrial power
supplies (as well as have lots of ways to vent heat), naturally
stronger and longer ranged than a laser mounted on a space ship?
Wouldn't this be an effective terrestrial defense against invading
spaceships?

Ground based lasers have the big advantage of being able to dispose of
waste heat far more easily. They may also be significantly larger,
and thus have more power and be able to focus farther. They have the
disadvantage of being occasionally hindered by clouds, and not being
able to use wavelengths shorter than the near ultraviolet. Large
installations will also be immobile, although laser trucks or trains
or surface ships or submarines may all be practical.

Here is an interesting article on ground based defense against space-
based attackers http://www.rocketpunk-manifesto.com/2009/06/space-warfare-i-gravity-well.html
..

--Particle weapons -- Great fun until the radiation kills you, no?
What about plating the casing in lead and mounting it on a ship far
enough away from crew compartments?

If particle beams can be made to propagate well through space, the
radiation shielding should not be a deal-killer.
http://www.projectrho.com/rocket/rocket3x.html#particle
Not to mention that crewed space warcraft are probably not all that
realistic.
http://www.rocketpunk-manifesto.com/2009/06/space-warfare-iii-warships-in-space.html

--FTL communication -- There seems to be a never-ending supply of semi-
plausible (and not so plausible) ways to get around that pesky speed
of light for spaceships. Realizing that FTL anything is probably
alchemist's gold, are there any similarly semi-plausible theories for
transmitting information FTL? I've heard of ansibles, but from what I
can tell, they make FTL spaceships look like microwave ovens in terms
of plausibility.

Ansibles are technobabble. Just a term an author made up for an FTL
radio.

The only plausible FTL-anything, whether travel or communication,
comes from bending spacetime with general relativity. Wormholes and
Alcubierre-style space warps let you get from here to there faster
than a beam of light shown directly from here to there - but these
beasties come with their own collection of quirks and oddities and
difficulties.

--Force fields -- as with FTL, recognizing their fairy tale status,
are there any semi-plausible designs for a force field? Or would I
have to go the route of Frank Herbert and just come up with some
vague, handwavium quantum effect? (not to knock the author of my
favorite SF of all time, of course).

It depends on what you mean by a force field. If you are looking for
an invisible immaterial barrier that stops matter dead in its tracks,
then no. There is no plausible or semi-plausible method of doing so.
There are ways to trap a plasma in a radio frequency field that looks
like it can screen out charged solar radiation in deadly solar flares
and other such space storms, but these will not do squat versus seeker
drones armed with long rod tungsten penetrators bearing down on you at
20 km/s, nor will it stop a megawatt beam of ultraviolet laser light
from vaporizing a hole through your craft's spine.

Also, remember, if you can see out, then light can come in. If light
can come in, you are vulnerable to lasers.

Luke
.

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