Nukes in Space: Why the Aliens Shouldn’t Be Worried

In this article:

  • In science fiction, coming up with technology that makes scientific sense matters.
  • Nuclear weapons are now a cliched way of bridging current weapons technology with that of the hypothetical future.
  • Simply put, nuclear weapons do not work in outer space the way we assume they should.  If you’re writing science fiction, find something else.  Now.

Today I decided to take  a page from Erik’s book and talk technology.  Nuclear weapons are one standard armament for future humanity, usually classed as a transitional technology.  If you need something bigger than a pistol, but can’t quite make a phaser, laser, or photon torpedo yet, nukes are the next best thing.  Unfortuantely, science tells us that they just won’t work in space the same way they do down here.  So, if we’re writing science fiction (i.e. fiction that falls within the realm of scientific plausibility) we need to look elsewhere.

There are plenty of examples of stories using nuclear weapons in science fiction.  Some older Star Trek novels about the early days of the Federation have starships carrying nuclear weapons.  They appear also in the made for TV movie Babylon 5:  In the Beginning, where John Sheridan destroyed the Minbari flagship Blackstar with nuclear mines.  Nuclear tipped torpedoes played a role in the early seasons of Stargate: Atlantis.  The human cruiser Daedalus employed them ineffectively against the Wraith (they were shot down before impact), though they were later transported into the enemy cruisers via Asgard beaming technology.  In all cases, they are seen as the best technology of an emergent species and are usually only marginally effective at best.  They provide a connection between our world and the one in the future, and give the storyteller a chance to make the audience feel intimidated when they see the most powerful weapon known to man fall short.

What we know about the basics of nuclear weapons makes them all the more fearsome.  When detonated, preferably a short distance above the ground where it can do the most damage, a nuclear device sends out massive successive waves of energy.  According to the Federation of American Scientists, roughly fifty-percent of this energy is sheer concussive force (the blast wave passing through the atmosphere), thirty-five percent is some form of thermal radiation (heat), and the remaining fifteen percent is nuclear radiation (neutrons, gamma rays, and residual radiation).  The incredible destruction of Hiroshima and Nagasaki using bombs with much lower yields than what is available today (or would theoretically be available to a space-faring humanity) illustrate the incredible destructive power of nuclear weapons.

The only problem is that nukes don’t work that way in space.  At all.

It turns out that space is missing a vital component:  atmosphere.  In this case, we aren’t talking about a simple lack of oxygen, since a nuclear reaction in a vacuum is quite possible; we’re talking about a lack of a conductor.  No atmosphere means that there is no medium through which two of the three waves of energy travel.  The blast wave owes much of its destructive force to the sudden compression and then expansion of the air around the detonation.  You can actually see this wave traveling through the air in some videos of nuclear explosions.    The air also provides the fodder for the thermal wave and conducts much of it away from the center event in the form of the massive fireball.  In short, without a substantial atmosphere surrounding a nuclear detonation, it could lose eighty-five percent of its destructive power.  The lack of atmosphere does have one “positive” effect on a detonation:  the radiation released affects a much broader area since there is no air to absorb it as it passes by.

What would happen if we were to detonate a nuclear weapon in space?  If NASA is right–and I presume they are–the results wouldn’t be all that impressive.  There would perhaps be a dull pulse of light and then…nothing in particular.  There would be a release of radiation (not all that much in the grand cosmic scheme of of things) and that would be it.

Therefore, nuclear devices really aren’t that useful in terms of science fiction (if we take science seriously*).  Deployed in a vacuum, they have no explosive power and no incendiary elements, leaving only an increased radiological yield.  A purely radiological weapon probably wouldn’t be of much use because, due to the significant amounts of radiation produced by the cosmos anyway, any potential spacefaring craft would already be heavily shielded against it.  A little more probably wouldn’t make much difference.

Do we need to dispatch with nukes altogether?  No, but we should use them in our stories intelligently.  Nukes are very effective inside an atmosphere, and therefore could be effectively deployed planet-side — that can include larger nukes for use in planetary bombardment (think Battlestar Galactica) and smaller, tactical ones for use on a battlefield.

If you’re looking for a good replacement, I would suggest railguns.  Real advances in recent years have convinced me that if we as a race are about to step into space, railguns will be the weapons we take with us.  They really are quite amazing.  That’s something I’ll discuss next Thursday.

Merry Christmas!

*Of course, an alternative method of dealing with it is to just call it science “fantasy” and then no one will care whether it makes scientific sense or not!


16 thoughts on “Nukes in Space: Why the Aliens Shouldn’t Be Worried

  1. Another place they would be useful would be deposited inside an enemy craft (e.g. Stargate Atlantis where the nuke are teleported inside the wraith vessels). Unless the enemy has no atmosphere inside their ships the Nukes would effectively rip apart the vessel from the inside out.

    1. Yeah, way to almost derail my short story submission, Dr. Melton! Nuke’s might not work in the vacuum of space (another thing I didn’t know about it, go figure), but an explosion from inside the ship’s contained atmosphere would be effective. It also seems to me that an explosion from within the ship would create a very powerful explosion; expanding gases in the frictionless void of space would have nothing to dampen them and nothing to lose heat to.

      I also envision something like a nuclear “flash-bang” weapon that would generate massive amounts of light and radiation that would disrupt optics and communication equipment.

  2. Not so sure about the footnote. The only difference between good fantasy and good science fiction is that in fantasy you can rewrite the laws of your universe so that (for example), magic works, while science fiction is supposed to follow the actual laws (as they are known) of the real universe. If you depart in scifi from the laws of physics (say, with warp speed) you have to provide an explanation that is at least plausible in terms of them (the warp envelope). But even in fanasy, where you have more freedom to write your own rules, you have to follow the rules you have written rigorously or you lose the structural integrity of your world. So I don’t think just calling it fantasy would let you get away with atmospheric effects in a vacuum–not if you want your work (as opposed to your bomb) to have a deep and lasting impact.

  3. Yeah, regarding getting the nuke inside an enemy ship, there are many munitions designed to penetrate and explode inside their target, bunker busters and some tank munitions spring to mind. This being born in mind, a rail gun propelling an armour penetrating slug with a nuclear warhead embedded deep inside could potentially cause massive damage to the traditional large sci-fi battleships, like in Battlestar Galactica. Sort of like a sci-fi Bismarck detonating the HMS Hood’s magazine with a lucky penetrating shot.

    This would also have the effect of bypassing any radiation shielding and cooking the internal electrical systems of such a ship should it survive the actual explosion for whatever reason (it’d probably make sense for crews to wear EVA suits and opperate in a vacuum to make hull breaches much less catastrophic, bringing the vacuum thing back into play).

    It also allows for the possibility of something resembling a cross between a shaped charge and flak, in that the nuclear explosion could effectively propel matter across a certain arc at an enemy vessel at high velocity without imparting unwanted thrust on the ship firing the munition in the first place, provided a missile style delivery system as opposed to mass driver is used.

    It’d also be quite a useful means of scuttling a ship to stop it being taken I suppose, so at the very least, nuclear scuttling charges would work.

    1. P.S. it’d also allow for mining areas of space with “nuclear claymores”, which due to the fact most likely space combat we could concievably fight with our technology would be determinned by viable routes determinned by gravity and orbital paths etc, wouldn’t be as hard as it sounds.

  4. Interesting article, but not quite the whole story. The area of damaging effect for a normal nuke in space would be about 1km… nothing in the grand scale of space combat, but still a reasonable area compared with other explosive devices. So, yes, nukes in space don’t give the result of say the Nostromo blowing up at the end of Alien, but then again, they would have a larger area of devastation than any other known attack. The radiation effects would probably be minimal to another spacecraft, already shielded against radiation for just normal space travel, but if the explosion is large and close enough to create an impulsive shock, the effects on the enemy ship’s hull would be impressive.

    Of course, all of this is relative, but the point is that most other weapons do require you to actually hit the opponent, which would also be quite hard.

    1. Thanks for your comment! Actually, one of the major points of the article was that with no medium to convey the force of the blast in the vacuum of space, there would be no blast radius at all. That would take away the vast majority of what we think of as the destructive capability of a nuke. We’d be left with just the radiological effects, which, as you noted, would probably be minimal.

  5. It’s important to say here that while it is true a small fission bomb wouldn’t produce as much widely dispersed heat as in atmosphere, there is a distinction between fission and fusion weapons, and a more sophisticated and much larger thermonuclear device like a hydrogen bomb (which uses a fission reaction to trigger a fusion reaction) would still generate a great deal of destructive heat, even in interplanetary space. The fusion reaction from one of our larger bombs would shed a lot of thermal energy and activity, and the less-dense gas substrate of space would make the fireball more diffuse.

    So a thermonuclear bomb detonated in space would still be destructive.

    1. That is a very good point, Henry. But, the post was more or less pointed at the tendency of Science Fiction stories, shows, and video games to conveniently ignore the differences between how explosions behave in atmosphere and in a vacuum. It’s in the same vein as most authors assuming that space is cold (it’s not; search for “Science Fiction Problems: The Vacuum of Space” for more info).

  6. Nuclear weapons in space by them selves are not very threating due to a lack of medium like stated in the article. But shaped nuclear weapon have been designed which project 85% of their force forwards towards their target making them more effective. But if you were to make a nuclear missile with a tungsten slug at the end at just a far enough distance away not to get vaporized by the shaped nuclear weapon with a medium like hydrogen gas between the nuke and the round in a sealed tube you would get a giant version of a light gas gun that is exponentially more powerful than anything that exists today. Acting as a nuclear powered anti ship kinetic weapon.

  7. Yes we know that nuclear weapons are near useless in space due to our vast scientific knowledge as the poster informs us. That is why Novas and Super Novas barely register in the scheme of things. They don’t produce shock waves in space as the original poster points out and their heat doesn’t conduct in a vacuum so solar systems near them have nothing to fear from such nuclear reactions except a bit of increased radiation. And we know radiation doesn’t affect things like electronics by EM bursts and so relatively small space ships (in the scheme of things) would have nothing to fear from something like the largest nukes Russia has open air tested (50-58 Megatons, 100 in full version) way back in the 20th Century would be useless in that regard, particularly if designed to be directional in burst and send out large shrapnel at high velocities (say large telephone pole style tubes of metal). Yes such things would be useless in space, especially in a hundred or more years with thousands of megatons used instead. Throw them near a spaceship and NOTHING would happen. A 30% yield of 1000 Megatons wouldn’t do much damage from radiation or shrapnel type payloads at high speeds against something like a quarter mile long spaceship…. Just utterly USELESS. 😉

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