The Effectiveness of Nuclear Weapons in a Vacuum

[Cadaei]

Much to my surprise, there is substantially less information on this topic on the internet than I initially thought there would be. Wikipedia has very little to go on, and I can't find any papers or serious discussions of this topic. There are many people asking similar questions on websites like yahoo answers, but the answers to these questions are shaky at best and never cite sources.

Also, let it be clear that I am not talking about high altitude nuclear explosions that were technically in space, as these programs deal almost entirely with their effects on the atmosphere and had little to say on the effects in a vacuum.

The question is simple: Would a nuclear explosion in the vacuum of space be more effective, less effective, or comparably effective than on Earth?

It seems to me that there are several pros and cons:

The pros:
-There would be nothing blocking the intensity of the gamma rays
-The range on the weapon should increase (a Wikipedia article said this was a benefit of the high-atmospheric nuclear testing that was done)
-Charged particles and shrapnel (whatever shrapnel is worth) would move at extremely high speeds and not be slowed down

The cons:
-No atmospheric shockwave
-No atmosphere to heat up


To me, it sounds like it may be more effective at annihilating human life and electronic devices than actually damaging structures. This begs a couple of more questions:

From a military perspective, would it be easier or harder to shield a craft from a nuclear blast than on Earth? Is it possible (viable) with current technology to shield against these gamma rays? Would conventional explosions be more or less effective?

From an "Armageddon" perspective, would close-proximity nuclear blasts even be a viable option for blasting apart or diverting asteroids or comets?

I would love to discuss this with anyone willing.

 

[Antiphon]

Your pros and cons are correct. Most of the terrestrial damage is from the radiant heat ignitining things and the the atmospheric shock wave leveling them.

In space the shock wave would be carried by the expanding mass of the vaporized weapon itself which would rapidly diminish in pressure with distance.

The shrapnel would completely depend on the construction and it's hard to say how much there would be or how fast it would go.

Large physical parts of a triggered but not-yet detonated fusion device travel at significant fractions of the speed of light prior to the ignition of the fusion capsule. This makes me think you could engineer a nuclear space cannon whose projectile would be unstoppable by any armoring.

 

[mfb]

Even on earth, the gamma ray shielding is not very good - just light nuclei with low density in the air. If you are so far away that the air absorbed a significant fraction, you are problably so far away that the intensity is not lethal anyway (depends on the yield of the weapon) or can be shielded.
I would expect that charged particles do not exceed energies of ~MeV/nucleon or ~MeV per electron, which is the energy released in the individual fission/fusion processes. Both can be shielded.
Shrapnels: No idea. Might be dangerous.

 

[Pkruse]

Perhaps some insight could be gained by studying how a light gas gun works. Here you have a high explosive detonation in an environment of Helium or Hydrogen. By comparing that to how the same explosives work in air, it may be possible to make some reasonable extrapolations to a vacuum.