Explosions in Space

I’m not talking the big bang here. The movie-style fireball explosion in space; thats all BS, right? Fire needs oxegen to burn- no oxegen in space, so no explosion, right? So a bomb wouldnt work on the moon? What if an explosion destroyed a shuttle in space from the inside out, what would happen? The fire would be quenched once the hull was breached?

Well, guns would work in space, because modern guns use an accelerant that has it’s own oxidizer.

I suspect the same may be true with other explosives.

And, modern explosives, even on earth do not create the fireball that is shown in movies.

Bang, dust, dirt and debris. No fire ball unless a lot of gas or something else is mixed in.

Explosives contain their own oxidizer, so they don’t need air. That’s the main difference between an explosive material and a (merely) combustible material. So a bomb would definitely work on the moon. And a conventional rocket may explode in a fireball because it contains both a fuel tank and an oxidizer tank.

But a bomb would be less effective in vacuum because there’s no air to transmit the shock wave. You’d still be hit by shrapnel, hot gas and radiated heat if you’re standing near an explosion.

If you consider just an accidental explosion on a spacecraft, the vast majority of whatever it is that explodes was probably intended for use as chemical fuel. So, it’s either got it’s own oxidizer mixed in (a la solid rocket fuel), or there is sufficient oxygen somewhere in a tank to combine with it. Otherwise why bring it up in the first place.

A bomb on or near a spaceship would work just fine, assuming it was designed for an environment without oxygen. They use bombs against submarines, afterall.

Very good point. And easy to understand.

Except that water transmits the energy of the explosion, unlike vacuum in space. As scr4 says, the hot gas, shrapnel, etc. from the bomb itself would still expand and do damage from the explosion.

That begs a question, scr4: ever lost an instrument to an explosion? Is that why you know the answer? :smiley:

Actually always kind of wondered about this. I understand there is no medium for the shockwave to travel through but then there is no medium to attenuate the hot gas and such flying at you which, I think, is a shockwave with stuff in it.

So, say a 50 foot radius from an explosion is lethal on earth. Is the lethal radius in space more or less than that?

If you find yourself in the path of a piece of shrapnel, it doesn’t matter if the bomb was 50 feet away or 500 km away.

…and that whole thing with an explosion in space causing a spreading, flattened, disc-shaped shockwave: is that Hollywood mumbo-jumbo, or is there any basis in fact? I can’t imagine why one plane would be favored over another.

I remember watching footage of nuclear weapons test explosions in space and the explosion was perfectly round, like the sun. Of course this was viewed from the ground, but I’m guessing it would be round if viewed from space.

Of course there wouldn’t be a disk shaped shock wave, it’s purely Hollywood. You COULD use a shaped charge that explodes in some preferential direction, but I have no idea why you’d do that in a disk…most shaped charges are designed to form a jet.

The attenuation of the explosion would be different than in an atmosphere. There would be no shock wave except for the explosive material itself, but the explosion and shrapnel wouldn’t stop until they hit something. On earth any shrapnel is going to hit the ground pretty quickly, plus the air can drag on any really small debris particles and slow them down. In space everything will continue to travel at its initial speed. Of course, everything is exploding in a rough sphere, so the chances of getting hit by something decrease by the cube of the distance.

Most explosions in the movies use gasoline to create the big fireballs. In real life there’s usually no fireball except from secondary explosions…if you shoot a tank it’s only going to fireball if you set off the gas tank. But gasoline only explodes if the conditions are exactly right. If you set your car on fire it’s very likely that the gasoline tank isn’t going to explode…you need a ruptured gas tank with gasoline volatilizing into the air before the fire starts to get an explosion. Remember the fire triangle! Fuel+Oxygen+Heat=Fire. Take away any leg of the triangle and there’s no fire.

Although slightly off topic, but interesting nonetheless, take a look at these pictures of an atomic bomb detonation taken with a 1/1,000,000,000 of a second exposure.

it just looks cool and dramatic. Hollywood has used such “directional” explosions in space ever since Alien (although the Hollywood effect is named, IIRC, for one in a Star Trek movie).

Oddly enough, the films which got space explosions right are Forbidden Planet and Silent Running – uniform spherical balls of light, a relatively low-tech solution. The one in FP is even silent (it’s in space and all. And almost 100 million miles away).

It’s interesting that George Lucas replaced the unioform fireballs of his orihinal Star Wars movies with such “directional” explosions in his revamped editions. He had it right, then changed it. Proof that it’s the dramatic effect that’s important.
By the way, space explosions can definitely contribute a lot of oomph, even in vacuum. If not, there’d be no point to Ptoject Orion’s nuclear explosion-driven impulses.

Well it wouldn’t be the first time. Han shot first, damnit!

True, but the propulsion “bomblet” design included a mass of some heavy, high thermal density substance (typcially, a tungsten liner or plate) which formed the bulk of the propellent. Also, the explosion was both shaped and contanted; some directed toward the nozzle (such as it was) which was essentially waste, and the rest to the pusher plate/shock absorber assembly which absorbed the momentum of the blast and released it at a lower instantaneous impulse to the vessel.


IIRC the first “directional” space explosion I remember was the ship Nostradamus being destroyed in the first “Alien” movie. Were there ones earlier than this?

<Nitpicky sci-fi fan mode: ON>
Shape of an explosions of a conventional bomb in space? Spherical, sure.
Shape of the explosion of a craft, even a spherical one? Depends on MANY factors like where fuel is stored, weapons are stored, secondary explosions, pressure changes. The new Death Star explosions make some kinda sense if you imagine that there were a lot of volatile materials in the equatorial trench (like engine banks or fighter hangars or whatever) that combusted before/while the main reactor finished going kaboom.

Then how do they make movie-fireballs?

With gasoline. Gasoline isn’t an explosive because it doesn’t contain it’s own oxidant.

Are you sure they weren’t simulations? I’ve never heard of actual space-based nuke tests.

There has never been a detonation of a nuclear weapon in space. If anything, fear of EMP would prohibit it, as do treaty agreements.