Re: [GZG] A Heavy Missile Question

["david smith" <bifsmith207@xxxxxxxxxxx>]

Thought you might like to read this. From a article taking about using nuke 
interceptors against enemy missiles.

The question then becomes: What would a low-yield nuclear weapon exploded in 
space 100 kilometers, 200 kilometers, or 500 kilometers above the surface of 
the earth, do to its target? It would clearly do nothing to the earth and 
very little to the space environment.

The weapons effects of a nuclear device detonated in a vacuum are very 
different from those of a bomb exploded near the surface of the earth. Blast 
and shock require a medium such as air or water to produce and propagate 
them. But space is a near vacuum.

The large thermal fireball associated with a nuclear explosion comes from 
bomb X-rays heating a large volume of air to luminescence. But there is no 
air in space, so no fireball develops.

A nuclear weapon in space has exactly two ways to destroy a target: soft 
X-rays and neutrons. The X-ray flash of a nuclear blast in space is very 
short, and the X-rays comparatively low in energy. But the instantaneous 
power in the radiation is enormous. When low-energy X-rays hit the outer 
skin of a warhead they stop, and their energy heats up a very thin layer of 
material. That sheath explodes away from the reentry vehicle, producing an 
intense shockwave that travels through the warhead. The shockwave is so 
intense that it is likely to destroy the structure of the intercepted 
nuclear weapon. In addition, plasmas may form on the powered electronics in 
the reentry vehicle, causing them to fail from "system-generated 
electromagnetic pulse."

The effect of X-ray photons depends on how "soft" the warhead is. Soft 
warheads are vulnerable at a radiant energy input of around 3 calories per 
square centimeter. (For comparison, desert grass bursts into flame when it 
experiences a thermal input of 6 calories per square centimeter.)

Weapons designers can harden a missile, but only at the cost of making the 
nuclear warhead heavier and significantly reducing its range. It is likely 
that hardening warheads to 100 calories per square centimeter is the outer 
range of what an entry-level missile and nuclear power can achieve.

The effect of X-ray photons also depends on how close the interceptor 
detonates to the incoming warhead. Estimating X-ray radiant energy in space 
is not difficult. By definition, 1 kiloton is the release of 1 trillion 
calories of energy. In a vacuum, roughly 85 percent of the nuclear yield 
appears in the form of X-rays. (In fact, only about half of the energy 
release is in the soft X-ray region, and hard X-rays penetrate too deeply 
into the skin or body of a warhead to produce an explosive "blow-off" and 
internal shock. Nevertheless, for the sake of this article and to be fair to 
nuclear proponents, we have used the full X-ray yield to determine the range 
of effectiveness.)

A 1-kiloton interceptor has a surprisingly long range against a soft 
warhead--somewhat more than 1.5 kilometers, or about a mile. The same weapon 
would be effective at only 250 meters against a "fully hardened" reentry 
vehicle.


> From: "john tailby" <John_Tailby@xxxxxxxxxx>
> > Subject: Re: [GZG] A Heavy Missile Question
> Date: Mon, 10 Apr 2006 18:54:47 +1200
>
> > The decayed blast radius effect is probably best accounted for in
> the anti matter missile.
>
> Whether even a large nuke has any radius effect in space depends on what 
> you define 1mu as equal to in real units like miles of kilometres.
>
> If you define the MU in terms of a planetary scale where say an earth sized 
> planet equals 6mu in diameter then each MU is a pretty big distance so the 
> effect of the nuclear explosion would be very limited.
>
> If you go for a much smaller scale where 1mu = say 100kms then would a 
> nuclear explosion have much of a blast radius? In space there isn't any 
> atmosphere so there isn't any blast wave. You might get a better effect if 
> you made the warhead into a directed charge and put some material that 
> could be fragmented by the explosion at the target. A nuclear powered 
> shotgun blast.
>
> I think that you will get the game all confused if you try and take a space 
> opera type game and apply real world hard physics.
>
> John


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