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So I'm going for a pretty realistic setting and I don't like shields, they break the style of realism I'm going for.

So for the most part defence is accomplished by dodging (which at the incredible ranges these combats generally take place is reasonable) and point defence lasers, which are destructive at short range but are not powerful enough to take down a torpedo before it hits the ships.

This leaves me the problem of torpedoes, they are guided which means dodging won't work, and can accelerate much faster than something with a pilot, allowing for H-Bombs slamming into the side of ships before the lasers can finish them because of their bulk. To say nothing of anti-matter...

Is there armour that could withstand that kind of blast? If antimatter is still gonna tear through it I can live with that.

Or Maybe a form of defence I hadn't considered? A way to trigger the bombs at a safe distance or destroy them without triggering the laser detection?

Notes:

The ranges are huge, light seconds and more.

The torpedoes would have extended acceleration in the hundreds of Gs and have plenty of time to get up to stupendous speeds before they are in range of the lasers.

The torpedoes have armour specifically designed to be resistant to lasers. (You have educated me on how good real lasers are but I still don't want them to feature to heavily in my story. They feel too "clean" or something.)

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    $\begingroup$ Nuclear bombs are actually pretty bad in space: basically all the destructive power bounces out into the void because it’s easier to go that way than push further into the ship. If you truly want some fun, nuclear and space based then you should look up the concept of a Casaba Howitzer (or maybe nuclear shaped charges) $\endgroup$ – Joe Bloggs May 1 at 21:33
  • $\begingroup$ Riding off Joe's comment, kinetic energy weapons would be quite effective and could probably better survive lasers $\endgroup$ – bendl May 1 at 21:40
  • $\begingroup$ @bendl With the ranges that combat generally take place at small random thrusts are generally enough to dodge unguided weapons. If you have unguided stuff, its mostly about closing the range. $\endgroup$ – Douglas May 1 at 21:48
  • $\begingroup$ This means that your thrust generally determines victory unless you include guided torpedoes. $\endgroup$ – Douglas May 1 at 21:49
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    $\begingroup$ Re: armour: look up the pusher plate designs of orion drive ships. There's probably an answer in there somewhere... I don't have time to write it today, but maybe someone else will oblige $\endgroup$ – Starfish Prime May 1 at 21:54
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Lets lead with some reality checking.

The torpedoes would have extended acceleration in the hundreds of Gs and have plenty of time to get up to stupendous speeds before they are in range of the lasers.

When people talk about the "tyranny of the rocket equation", they mean the way it stomps, hard, on stuff like this. A rocket with both stupendous force (to develop those hundreds of gravities) and stupendous efficiency (to keep running for long enough to reach those stupendous speeds) is astonishingly high tech to the point of being nigh-on-impossible. Generally speaking you get one or the other of those two things, not both.

You might be able to do it with a nuclear saltwater rocket, but even then "hundreds of gravities" seems like a bit stretch.

The torpedoes have armour specifically designed to be resistant to lasers. (You have educated me on how good real lasers are but I still don't want them to feature to heavily in my story. They feel too "clean" or something.)

Lasers powerful enough to reach out and swat things across tens or hundreds of thousands of kilometres of space laugh at armour, and small torpedoes that need to carry a big warhead and a big engine can't afford to haul much armour anyway. For a realistic scenario, you'd be better off taking an approach that simply says that powerful lasers are too big and too inefficient to be useful on a warship that isn't entirely made of heat radiators, which would then be limited in other ways.

H-Bombs slamming into the side of ships

Firstly, don't use plain old nukes. In the very best scenario, a nuke going off in contact with the hullk of an enemy, half of the energy released will be in the hemisphere facing away from the ship, and so will be wasted. Actually hitting something manoeverable that can see you coming from a million km away is far too hard to be worth trying.

Instead use Casaba Howitzer type nuclear shaped charges that can (largely) direct a nuclear blast at a target from hundreds or thousands of km away. Its an energy weapon, sure, but no-one would ever describe a focused nuclear explosion as too "clean" or "neat". Shorter ranged than lasers too.

(also, if you genuinely have torpedoes that can hit a percent of the speed of light, you might just consider using fragmentation warheads. cheaper, simpler, still pretty devastating)


Now, on to your actual question.

Is there armour that could withstand that kind of blast?

...mmmmmmaybe? Now, Casaba Howitzers grew out of the Orion project, a propulsion system that involved using nuclear blasts to push spacecraft. Obviously, said craft would need to be fairly nuke resistant. A close enough blast would still smash them, but even then the pusher plate would help. Armouring your whole ship like that is probably far too heavy and impractical but a spacecraft design that incorporated a physical shield is potentially a fun one. Big dense metal slab with generous layers of radiation-absorbing material, shock absorbers, whatever. Face towards enemy and joust with nuclear lances!

Just remember that any blast close enough will fry you. Now, if your defences are good enough, you can force incoming torpedoes to detonate too far away from you to make a one hit kill, simply by persuading its onboard computer that it will certainly be wasted if it gets any closer.

And speaking of defences,

Or Maybe a form of defence I hadn't considered?

You can see torpedoes coming. At 100km/s they'll take nearly an hour to cross a light second. At 1000km/s they'll take an hour to cross 10, obviously. Unless you're using warp drives, you'll almost certainly not get as fast as 10000km/s (0.03c), so the target has lots of time to think. Any drive system capable of pushing an object that fast in a short time is so energetic that there's no way to stealth it. The target will see you.

Now, a warship might be quite a tough thing. You need a big blast to kill it, or many small ones. A torpedo on the other hand, that has no mass to spare for significant armouring and toughness. You need waaaay less energy to mission-kill it, let alone outright destroy it.

How do you get to an incoming missile far enough away to kill it safely? Use interceptor missiles. They're related to torpedoes, so have the same incredible drive systems and can reach out to extreme range to meet their targets in short order. Interceptor missiles can use warheads that aren't much good against ships, because their targets are much softer. This makes your interceptors smaller and cheaper, or faster and/or more manoeuvrable than their targets.

  • Your lasers are crap at long range, but you can use bomb-pumped lasers mounted on a torpedo to swat an enemy missile at range, faster than it can dodge. X-ray and gamma-ray lasers are impractical to armour against. Potentially more precise and perhaps even longer ranged than casaba howitzers... depending on how you like your tech you can swing it either way.
  • Hitting a fleck of gravel at 1000+km/s is likely to be devastating. An interceptor could have a fragmentation warhead that projects a cone of grit towards its target. The odds of any one speck hitting a target are low, but a big cloud of probabilistic doom isn't something that you want to throw your limited numbers of expensive torpedoes into. Just get close enough to your target that the grit cloud is dense enough to be a problem. Worst case you make them waste fuel and time evading it, softening them up for the next interceptor. The cone of debris is moving away from you at speed, so it is no threat to your own counterattack or your warship itself.
  • Casaba howitzer them back! Nuking nukes is a perfectly viable tactic.

Antimatter is another, uh, matter altogether. Probably worth saving for another question. Suffice to say, that whilst it is definitely very useful, it isn't really earth shatteringly gamechanging in a warhead (but useful in a rocket). Don't worry about it too much.

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Automated Defense Drones

The ship has kamikaze drones that are designed to crash into a torpedo and self destruct taking it out before it can reach the ship. Just like the torpedos can follow the dodging ship, the drones follow the torpedos.

It's basically a shield designed to destroy anything that comes within range. Torpedo torpedos if you may....

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  • $\begingroup$ Crashing into a possibly evading target that is approaching you at hundreds or thousands of km/s is likely to be Quite Hard. $\endgroup$ – Starfish Prime May 2 at 9:59
  • $\begingroup$ How is it any harder than the torpedo crashing into an evading ship? At least you know what the torpedo is aimed at. You're already between the torpedo and it's target. $\endgroup$ – Thorne May 2 at 10:04
  • $\begingroup$ The ship probably won't be evading with 100Gs of thrust. Also, as already observed elsewhere, crashing a torpedo into a ship is silly. $\endgroup$ – Starfish Prime May 2 at 10:07
  • $\begingroup$ Anything the torpedos can do, so can the drones and at the end of the day they need to get past the drones to reach the ship. $\endgroup$ – Thorne May 2 at 10:11
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    $\begingroup$ Just leaving this here: en.m.wikipedia.org/wiki/Multiple_Kill_Vehicle $\endgroup$ – Demigan May 2 at 10:55
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Armor

Good luck with this. In our current world we've way outpaced our ability to protect by our ability to destroy. Our bunker busters can push right through multiple feet of defense and explode on the other side. Not certain about your spacecraft, but military cruisers' armor tends to be under 3".

Possible Solution

One nuclear-defense method we're looking at is firing counter missiles at missiles. You could do something like this; counter torpedos to the offending missile.

These counter missiles don't need anywhere near the payload of whatever they're aiming to take out, so they can be made smaller, cheaper, and more maneuverable. These can be fired, potentially, en masse, so even if the enemy's torpedo could potentially dodge a single counter-torpedo, dodging an entire school of counter-torpedos is a much harder affair.

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A question, to start: why are the point-defense lasers so ridiculously-short-ranged? If they're effective weapons, they should be good out to hundreds or thousands of kilometers - in space, little impedes laser energy. On Earth, right now, laser weapons can blow things up at better than a kilometer, and this is future-lasers.

So lasers would effectively be "if you can see it, you can hurt it" kind of weapons. "Dodging" would only be feasible at ranges greater than a light second (300 000 km). This makes the use of nuclear torpedoes much more difficult, because ECM would then become the defenders' friends. Jam the control signals. Present false positives to the torpedo's sensors. Etc.

Space is really, really big. If you're within 100m, armour isn't going to be the solution - but no space battle is ever going to be joined at that range.

So the overall answer to your question - dodging is fine, particularly for torpedoes, because ranges are going to be long.

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    $\begingroup$ Depends on the index of diffraction for the lasers - there's a degree of diffraction that all lasers have to deal with due to the properties of light. $\endgroup$ – nick012000 May 2 at 5:32
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    $\begingroup$ Because if you want to fire at something lightseconds away without losing too much energy you need something on the lines of a kilometer sized focussing array? Lasers are kind of bad at ranged weaponry, thats another reason why we still have mutli-kilometer range kinetic weapons lasers are mostly in prototype stages they may never get out off. Also having a large cloud travel with your ship can provide protrction against lasers but not kinetic bombardment... $\endgroup$ – Demigan May 2 at 11:03
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  1. Radar detects torpedo when it is a long, long way away. Radar is fast because it is light. Radar works better in space than it does on land.

  2. Torpedo knows it has been detected because it sees radar. It starts dodging around.

  3. Lasers light up torpedo. Lasers are in a circle; possibly a frowny face. If all components of laser circle are not reflected back, laser circle moves in direction to put missing frowny face edge back on torpedo.

  4. Railgun uses laser targeting circle and launches a fleck of beryllium at 0.8c. Be fleck changes torpedo into things that are not torpedos.


  1. New torpedo is made of stealth stuff that does not reflect radar.

  2. Radar dish is retrofitted to use visible light. Visible light is fast because it is light. Visible light works much better in space than it does on Earth.


  1. New new torpedo is covered with Vantablack. Frowny laser face does not reflect...
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  • $\begingroup$ Using active sensors over a range of several light seconds probably isn't worth the effort, inverse-square being what it is (and having to be applied twice, cos the reflected signal will spread out too). A railgun capable of firing at 0.8c is the sort of thing you'd use instead of a torpedo, not against one! That's a ship-killer all by itself. $\endgroup$ – Starfish Prime May 2 at 10:53
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First of all, I'm going to pick on the fact that you stated you wanted a realistic setting. Your missiles parameters will not work out, you can either have high delta V or you can have high acceleration, but not both (unless you use ridiculous amounts of energy) I'd suggest reading up on Atomic Rockets what kind of drive you want to use and what kind of delta V performance you'll get

If you do want these kind of performances, your worry about nukes is gone: Nuclear warheads or even antimatter warheads will not noticeably increase the amount of damage done by the kinetic energies involved.

Thus you end up with 2 types of missiles:

Chem-fuel: These are high acceleration, short duration weapons, thus they need to be fired relatively close to the enemy to be still within range, otherwise the enemy will simply dodge them given enough time.

Main Drive: These missiles have a scaled down version of whatever main drive you use on your ship, thus likely involve a nuclear reactor. They are correspondingly big, essentially a one-way mini spacecraft, and thus few in numbers.

Since the range of simple nukes is very limited in space, defense is much the same against nukes as it is against kinetic impactors.

For defense you have the following options:

Counter missiles: These are especially effective against Main Drive attack missiles, since they are much cheaper, but they may work as well against other attack missiles.

Lasers: Lasers are long ranged weapons, a 1000km laser has a 100s to intercept a 10km/s incoming missile, and is reusable, unlike the missile. The exact breakdown between laser and missile is very much up to debate and up to the tech involved.

Particle Beams: Neutral particle beams also have enormous ranges, and has the benefit of not requiring large, exposed mirrors. How they compete against lasers depends on the tech.

Railguns: These may work against attack missiles, as any projectile traveling 5km/s hitting anything going 10km/s the other way will deal massive amounts of damage, and missiles can't afford any redundancy.

Decoys: These will likely only work short term as final defense, but any near miss is a wasted missile.

Armor is the last line of defense, but mass intensive, the bane of spacecraft. How effective it is really depends on your exact parameters of the tech available.

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Anti-torpedo missiles, guided by radar or lidar or by torpedo exhaust heat signal. Being short-range, they would not need a lot of fuel and should hence easily reach enough acceleration to match any course changes by a torpedo.

Decoys. A space fleet is surrounded by lots of decoys with the same radar, lidar, and heat signature as a warship. Unless such decoys are much more expensive than torpedoes, you could easily build enough to match the number of torpedoes. Regularly changing configurations of warship/decoy placement could fool machine learning.

It is worth noting that since there is no air in space, the shockwave of a nuclear explosion would dissipate quickly, probably over a few kilometers. Radiation is a greater issue, but shielding and distance should protect from that. Hence, a near-miss (in astronomical terms) of an H-bomb torpedo would not cause any major problems. You would need a direct hit to cause massive damage.

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  • $\begingroup$ Decoys don't really work in space, if you're using rocket engines. Even nuclear ones. Exhaust plumes are very bright hot and easy to spot, and give a good idea of how big and heavy the target is. You'd have to use decoys the same weight as your actual warships, with the same engines, to reliably fool people! $\endgroup$ – Starfish Prime May 2 at 10:12
  • $\begingroup$ Heavy decoys might not be a problem - they would still be a lot cheaper than actual warships. Fuel expenses might be a problem unless fuel is fairly inexpensive. $\endgroup$ – Klaus Æ. Mogensen May 2 at 11:51
  • $\begingroup$ Depends where your expenses are going. You still have to build something that: looks like a warship, weighs as much as a warship, has the same engines as a warship and the same endurance as a warship. Given that the principle armament of the OP's warships appears to be missiles, your decoys have ended up basically indistinguishable from a warship with empty magazines. At some point, you've got to wonder whether arming your decoys might make them a bit more useful... $\endgroup$ – Starfish Prime May 2 at 18:53
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Water ice. Water has a very high specific heat capacity, which means that using it as a layer of ablative armor to protect your ship against energy weapons would work very well - and, since there's no material in space for shockwaves to propagate through, nuclear weapons would be forced to act as energy weapons and inflict their damage through radiation, barring a direct hit.

Additionally, water ice is a resource that is abundantly available in space, which means that field repairs following a confrontation would be very straight-forward - just head over to the closest icy asteroid and start bucketing it up and sticking it on your ship.

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  • $\begingroup$ I’m not sure why this got downvoted. Water ice is a viable sort of armour against energy weapons, which is what nuke are when they’re set off in space. It’s an ablative armour, sure, but every armour is when you’re talking about energy weapons. $\endgroup$ – nick012000 May 2 at 21:36
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EMP

The electromagnetic pulse is real and has been weaponized. You can check out one of these systems for yourself: here

As they said in the article, it hasn't been tested on military hardened electronics but it might provide you with something real to build off of.

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  • $\begingroup$ Can you expand on how that would help with regards to nuclear torpedoes? $\endgroup$ – bendl May 1 at 21:40
  • $\begingroup$ Well it wouldn't help much for torpedo but then again neither would another missile or a laser. $\endgroup$ – Rob May 1 at 21:43
  • $\begingroup$ This would just disable the torpedo which could be useful provided the torpedo was far enough away to be dodged. I can imagine that there'd be a mechanical failsafe detonation switch so that wouldn't be enough to prevent it going off either. $\endgroup$ – Douglas May 1 at 21:50
  • $\begingroup$ @Douglas Agreed, however, you're alternatives are guaranteed to result in an explosion as well and the emp won't be rendered useless during a thunder storm. $\endgroup$ – Rob May 1 at 22:06
  • $\begingroup$ It would seem like any undirected EMP (of the sort in your link) would do as much damage to the launcher as the target if it were being used defensively. Directed energy countermeasures are exactly what was dismissed by the author. $\endgroup$ – jdunlop May 1 at 22:06

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