WMDs IN SPACE

[Hai-Etlik]

What constitutes a 'Weapon of Mass Destruction" depends on the setting. In plenty of space settings, fusion or even antimatter warheads are conventional weapons to use against other spacecraft, and inert lumps of matter (going VERY fast) are WMDs capable of wiping out planets.

[DAT]

Originally Posted by Darekun

These are even easier to get rid of. In the real world, it's hard to get a neutrino beam, but for the ones we've used in the lab, there's one thing they have a significant effect on: heavy nuclei. That effect is… meltdown. ...

I question your science on this.

The term "meltdown" is not what you want if you want to imply an early detonation, you want "prompt supercritical event".

The term "meltdown" implies an overheating and melting of a material, which implies a depositing of energy in the material from some source. Neutrinos might interact more with heavy nuclei than light, but the interaction probabilities for heavy nuclei are still extremely small. Your beam weapon would have to use a tremenous amout of energy to get a minor heat up is a small fissile material pit in your nuke. The mass of heavy metal in your nuclear weapon is fairly small compared to the heavy nuclei in your Os or Ir armor on your military space craft. The neutrino beam would have to heat up a lot of materials before it could heat up the Pu in a nuclear warhead enough to matter.

-Dan

* Not sure if this is the correct term, but it is something like that.

[lwcamp]

Originally Posted by Darekun

These are even easier to get rid of. In the real world, it's hard to get a neutrino beam, but for the ones we've used in the lab, there's one thing they have a significant effect on: heavy nuclei. That effect is… meltdown.

You would need an extraordinarily intense neutrino beam - a beam that would deliver a substantial radiation dose to anything it passed through.

Originally Posted by Darekun

Proton-proton fusion should be doable, and no resource shortage will stop that.

Proton-proton fusion will take tens of millions of years to fuse even a minor part of the fuel, and that even with containment temperatures and pressures found in the cores of giant suns.

Originally Posted by Darekun

Biological weapons are also somewhat difficult when your opponent is in a spacecraft. Vacuum generally has more stopping power than any pathogen, and any damage control team that shows up to deal with air escaping to vacuum will be suited up, and they'll need to be in an area with working life support before they take the suits off.

At the expected closing speeds of space conflicts, biowarfare microbes will be self-sterilized by the energy of their impact with the hull.

Originally Posted by Darekun

The spacecraft also makes the generic caustics usually more effective against hull than crew, and even then, not that effective. The targets need NBC-level protection just to keep the air in and fresh.

Caustics are not terribly effective against structures except over long time scales, and in any event the energy of impact between the chemicals and the spacecraft hull will dissociate the chemicals (and cause far more damage than the chemical ever will - which for diffuse gases is practically nil in any event).

Luke

[Darekun]

Originally Posted by DAT

The term "meltdown" is not what you want if you want to imply an early detonation, you want "prompt supercritical event".

Definitely not a detonation. The experiments so far have pushed them barely supercritical.

Originally Posted by DAT

The term "meltdown" implies an overheating and melting of a material, which implies a depositing of energy in the material from some source.

Er, it's not directly heating the target, it's doing something like catalyzing nuclear decay. The thermal energy deposited was not measurable, it just turns the implosion sphere into a little RTG. (I've never seen anyone more than guess at the mechanism, though.)

Originally Posted by DAT

The mass of heavy metal in your nuclear weapon is fairly small compared to the heavy nuclei in your Os or Ir armor on your military space craft.

Now that may be trouble. I tend to assume either offense will continue overpowering defense, or superscience defenses. Still, this wouldn't doom it; simply use the handy neutrino beams(which are limited superscience anyway) as the explanation for an existing beam type's stats, and note that as a side effect they cause meltdowns on the scale of a Spaceships turn.

Originally Posted by lwcamp

You would need an extraordinarily intense neutrino beam - a beam that would deliver a substantial radiation dose to anything it passed through.

From what I read, the ratio was considerable — the conventional beam effect wasn't measurable on even the same target. Still, side effect of a weapon would work.

Originally Posted by lwcamp

Proton-proton fusion will take tens of millions of years to fuse even a minor part of the fuel, and that even with containment temperatures and pressures found in the cores of giant suns.

So what would you say is the constraint on fusion?

[lwcamp]

Originally Posted by Darekun

From what I read, the ratio was considerable — the conventional beam effect wasn't measurable on even the same target. Still, side effect of a weapon would work.

If you have a reference, I'd be interested in reading it. I am a bit skeptical, however, since one of the most intense sources of neutrinos we have today are fission reactors, and the rate of fission in the reactors is described very well without considering the effect of neutrinos.

Originally Posted by Darekun

So what would you say is the constraint on fusion?

Proton-proton fusion on the scale of a city block or smaller is likely magitech of a pretty high degree. You need the plasma to be optically thick to the <i>bremsstrahlung</i> x-rays it produces, because it emits many orders of magnitude more power in bremsstrahlung than it gains in fusion - and this requires a huge, dense plasma. It also generates power at a pitifully slow rate - the sun has a specific power of milliwatts per kilogram, compared to kilowatts per kilogram for an automotive piston engine, and tens to hundreds of kilowatts per kilogram for a high performance gas turbine. The reaction is so slow that there is probably no way to get it to explode.

Deuterium tritium (D-T) fusion is the most practical form of fusion. It suffers from various plasma instabilities that make it not work when we try it in the lab, but we are working on it. Well, except that we can get D-T fusion to work when you compress it with enough speed and energy - as evidenced by the so called "hydrogen" bombs. D-T fusion has various drawbacks: it emits 80% of its energy in the form of very energetic neutrons, it requires a radioactive fuel (tritium) with a half life of only a decade (although many designs create or regenerate the tritium on the spot using a reaction of neutrons with lithium, and you certainly have enough neutrons). There may be ways to explosively ignite a D-T reaction in the absence of a fission primer in a science fiction setting, but I am not going to discuss the details.

Only two other forms of fusion appear to be able to work at sub-planetary scales - Deuterium deuterium (D-D) fusion, and deuterium helium-3 (D-3He) fusion. D-D fusion offers no advantage over D-T and is much harder to ignite. D-3He is also much harder to ignite than D-T (although slightly easier than D-D), but has the advantage that it produces very few neutrons. A number of other forms of fusion have been proposed, mostly on the merit of being neutron free (p-11B, 3He-3He, and others), but they release more bremsstrahlung than they create and the outlook for these is bleak.

Luke

[Lord Carnifex]

Here's how I handled this in my last space opera game:

The PC's were members of the military forces of the Imperium, an amoral bunch at best. The Imperium's outlook could be best summed up as "ruthless efficiency"; it's easiest to think of them as a force in a resource-management strategy game, played by a 'player' who wants to maximize the resources available to him and win the game.

FTL travel is slow and difficult, and Earthlike garden worlds few and far between. Terraforming is pretty much impossible. So, the Terrans and any other FTL-capable species commonly settle worlds that are far from perfect.

The Imperium discourages use of WMD's. Chemical and biological weapons don't see much bettlefield use, because chances are that the battle is taking place on a planet where everybody needs sealed armor and life support anyway. Garden worlds are precious enough that no one wants to risk poisoning them - the Imperium can plant so many more productive subjects on a world where they can breathe without domes.

Nukes and planet-killing asteroids aren't used because planet-side warfare is fought over resources. Destroying the settlement or colony one is trying to capture is usually counter-productive. Even if you can rebuild, new colonies and starbases are expensive and time consuming to build - it's almost always better to take over existing ones rather than start over from scratch.

Plus, all sides have access to about the same level of weapons. There's a kind of gentleman's agreement in place among all the possible combatants that "if I don't use them, you won't use them". They don't worry about Mutually Assured Destruction as such, but no-one wants to trigger a WMD exchange that leads to too many productive subjects killed, valuable infrastructure destroyed, or useful resources wasted.

[Gold & Appel Inc]

Originally Posted by Perfect Organism

Add layers of bureocracy, outdated procedures and neglected technology over a long enough period of time and the WMDs will probably be effectively impossible to use. 'Nuclear fusion weapons require approval by both houses of the Terran senate before they are used, but the lower house was disbanded in the electoral reforms twenty years ago. I'm afraid you will have to wait for the legislation to be revised before you can use them...'.

"Approval passed through the House no problem, but the Fatcat Party is threatening to filibuster it in the Senate if we don't sign off on another tax cut for the top 1% income bracket."

"But that's literally impossible! The top bracket is already taxed at 0%!"

"Yep..."