Suppose NASA/Airforce/Navy had some kind of spacegoing battleship…
:dubious:
…with steel armor a thickness on par with seagoing naval vessels.
Now lets just say “the enemy” has nuclear capability and can launch a payload to orbit
Lets say the warhead has a 20 kt yield (approx equal to Hiroshima and Nagasaki nukes).
Without air to transmit blast damage, how close could a detonation occur without a hull breech?
While I can’t outright answer your question, I’ll add a couple of complicating factors –
I recall from the hayday of “Star Wars” missile defense research that a nuclear weapon detonating in vacuum would still produce an “X-ray shockwave,” which was necessary to the functioning of Edward Teller’s proposed space-based nuclear powered laser system. I’ve no idea what the real kinetic destructive power or range of that shockwave might be.
An attacker might very well provide his nuke with a fragmentation jacket – say, a layer of tungsten penetrators like modern tank guns fire. The materials vaporized by the detonation of the bomb itself would, I should think, be sufficient to propel the penetrators in all directions at speeds well in excess of what atmospheric drag would permit, and likely perforate, if not shred, the space battleship at a substantial distance beyond the destructive range of its own shockwave and thermal effects.
Wag:
You’ve got a 1000 kg warhead that’s mostly iron avg MW = 56
So you’ve got 17500 moles of material to gasify.
22.4 moles per liter at 1 atmosphere and room temperature.
So those 17500 moles’d get you about 392986 liters of gas at STP.
That’s only 392 cubic meters.
Let’s heat the gas to 10,000,000 °K
That’ll increase the volume by about 33,000 fold
so about 12.9 million cubic liters.
The radius of a sphere that size is about 145 meters.
That represents an overestimate of how big a sphere of atmospheric pressure gas your bomb could generate. Presumably a sudden gust of wind at several thousand miles per hour and 1 atmosphere pressure would be enough to damage a battleship.
I think you might be safe out at a kilometer, where the pressure wave is down by a factor of a thousand or so.
Of course a kilometer is awfully close to be sitting to a 300 meter diameter sphere radiating black body at 10,000,000°K. Chances are good that direct thermal transfer would cook your battleship at that distance.
Pretty damn close.
The proposed Orion rocketship would have used hundreds of detonating atomic bombs blasting against a pusher plate to propel it.
Without an atmosphere to transmit the blast energy, all you are really doing is heating the crap out the very top layer of the ships metal. Your Obama Sucks bumper stickers are likely toast, but that 1/2 inch of steel plating is just gonna get warmed up a bit IMO.
My WAG is anything more than couple hundred feet away dont mean didley (not considering radiation effects messing up electronics/frying ensign’s nads).
Adding to Squink’s comments Mr. Neutron (and there would be many of him) would cause some prompt and delayed effects on you, your buddies, and transmuting some that steel. At 300 meters your craft would not be DNA friendly.
This section of the “Space Wars” episode of History Channel’s “The Universe” discusses nuclear weapons in space, mostly against Earth. It starts at 3:00. (http://www.youtube.com/watch?v=Id09x6TtAyo)
You don’t need a hull breech to kill your enemy if you can get enough radiation, such as gamma radiation, to fry him.
To protect against both neutron radiation and thermal/x-ray vaporization your best bet would probably be something like the beryllium ablative shielding used on the Apollo command modules. So a thick outer coat of that over hull steel for strength and protection against x-rays and gamma sounds like the best bet. Sort of like a certain fictional space-battleship.
If you have a battlestar, they can take nuke hits all the time and keep on moving :).
BTW, that’s a related question: in our fictional scenario I can easily accept surviving a near-miss in space (strong armor, radiation shielding, etc.) but what kind of unobtanium-grade armor are we talking about that can withstand a direct hit from a nuclear weapon (for purposes of discussion, let’s assume the trusty ol’ Hiroshima 20kt example)?
Obviously, wreckage can and did survive near ground zero of the Hiroshima and Nagasaki blasts, albeit in awful shape. What kind of materials/thickness are we talking about that can actually survive an impact and detonation?
Seems logical, but unless you have some kind of directional blast (using some kind of pretty nearly indestructible barrel?) you’d have the the penetrators rushing off in an expanding sphere, which means the effectiveness (measured as the amount of penetrators hitting an object) would be inversely proportional to the square of the distance to the blast, and unless you’ve got targets all around the bomb, you’re wasting over 50% of the energy anyway since it’s blasting in the wrong direction entirely. On the other hand, it’s not as if the penetrators are going to slow down any time soon, so you may still hit a lot of stuff - though it probably won’t be your target.
Wouldn’t the penetrators (and any other solid matter within a few meters of the blast) vaporize shortly after detonation?
I think you are probably better off just using cheap metal penetrators fired from an electromagnetic rail gun.
If you check out Operation Crossroads stuff:
The test “Able” blast was an airdropped (23kt) weapon that detonated 615 yards away from (and 520 feet above) the old battleship USS Nevada:
Yeah, I’m familiar with that stuff. The difference there is that you’re still stuck with air and water to transfer pressure damage to hulls, and the bombs didn’t hit a target head-on.
Alas, probably as close to “real life” as we’re gonna get (thankfully!).
Well, I was going to mention the atmosphere…
But even with the atmosphere to transmit shock, an airburst did not sink the Nevada.
It did sink other, less armored, targets. Even this is mitigated on the specific facing/aspect the target was in relation to the blast.
The underwater blast (test “Baker”) did a whole lot more dramatic damage, because water does not compress as much as air does, so it transmits more “shock”. It caved in the whole starboard side of the USS Arkansas.
I assume a vacuum blast would not, to the eye, appear to inflict impressive physical damage to a large stoutly built target.
…It’s the only way to be sure.
and if you are anywhere near it, you’re going to get some of it also.
As I understand it, it is theoretically possible to make a shaped nuclear blast. The idea is, you detonate several small nukes surrounding a much larger nuke, and if timed properly the small blasts will shape the main one into a jet. Rather similar to how shaped chemical charges work, I believe. Making something like that compatible with penetrators would be challenging though.
I’m assuming the penetrators would be made of some kind of material that (mostly) won’t vaporize. Maybe a hollow sphere made of some brittle metal with some sort of gas or whatever on the inside to push it away from the blast.
ETA: as msmith537 said: In space, I would think a rail gun would be simpler and more effective, though.
Actually, the goats in the quoat–er, quote–died of radiation sickness, not blast pressure. So figure that whatever level of armor the ship had would NOT be enough to save your space cruiser’s crew.
I know people LOOOOOOVE the idea of rail guns, but has anyone ever made a WORKING artillery-grade rail gun? My understanding of them is that they’re completely unreliable and impractical at present. Might as well say that, “in space, photon torpedoes would be simpler and more effective.”
Well, considering there’s nothing to slow your “bullets” down, that could make any kind of directed kinetic weapon pretty effective at much larger ranges than an undirected burst of rays or particles.
ETA: I’m fine with rocket weapons, but they just don’t sound Sci-Fi enough 