What would space combat really be like?

[Fishbowl Helmet]

Okay, first off, sorry for how I handled myself in the other thread. It's an interesting topic, so let's open it up for conversation.

There are a few good articles I've found on the topic of realistic space combat: here, here, and here. Each has its own take on the topic and I think they're all worth reading.

So, to spitball on the topic, the really important thing here is the speed of light. Assuming things like FTL drives aren't used during actual combat, and that weapons and sensor systems are limited to the speed of light, we can make some really cool guesses as to what this might actually look like.

First up, speed. Relativistic speeds are roughly 10% the speed of light. Let's say our ships are traveling slower than that, but the specific speeds don't matter much until the distances between two ships is really small, relatively speaking. Speed doesn't matter, practically speaking, because of sensors and computers. Once a hostile detects a target, their computer can easily calculate projections for where the target is now, and where the target will be when the weapon would hit them (if they're actually there). Remember speed of light makes things tricky, which means sensors are really important.

Second, sensors. Assuming information is limited to the speed of light, any type of sensor a ship could have would be limited to 299,792,458 m/s. Now, assume you detect a ship at 5 light minutes out. The position you detect that target at is a 5 minute old snapshot. Track the target for a few seconds (or whatever) and your computer can project where the target is now (real time), and based on velocity, project where it will be when your weapon would intercept them. So we're limited to the speed of weapons.

Third, weapons. Your weapons are limited to the speed of light. So it would take a laser another 5 minutes to reach the projected location of the target. So you're dealing with 5 minute old information, a shaky estimation of where the target is in real time, and an even shakier projection of where they will be 5 minutes in the future. The closer the targets are to each other, the easier this becomes, until they reach eyeball range, but, more than likely, things will be over long before that happens.

But, speed does come back into things once we're talking about ranges in the 1-2 light minute range. Close enough where your projects are less of a spitball and more likely to be accurate. If you're moving too fast you can't maneuver effectively to avoid an enemy firing at your projected location. Too slow and the enemy can hit you even easier.

Seems like the best thing to do would be fire a shot at each of the three possible locations you have: initial contact (old info), current estimate (shaky info), projected location (really shaky), and hope for the best. Basically keep shooting at these three spots until you tag them. Or they tag you. All the while you're both maneuvering as best you can, but again, too fast and you're an easy projection, too slow and you're a sitting duck.

I think space combat will be more akin to predicting the path of a storm than either the naval battle or dogfighting analogies suggest. Another possibility is submarine warfare, but that doesn't work either as the key is stealth and first strike. In space stealth is essentially impossible unless you start using some really impossible technology. (Impossible in the sense of not even theoretically possible from current theories.)

Does that sound about right? Am I totally wrong? What do you think?

 

[Galacticdefender]

Leviathan Wakes and Caliban's War have some pretty good, fairly realistic space combat in them.

And I actually think there could be a bit of a naval aspect to space combat. One side would build a warship, then another side would build a warship to out fight that warship, then other warships could support those warships. In that regard, I think there still might be a bit of navel-ness to space combat.

 

[Rodders]

The lost fleet series by Jack Campbell was praised for it's realistic space combat.

 

[Bakerman]

This website is a fantastic resource for all things space-warfare, and space-travel in general. The most important thing to remember is TANSIS: there ain't no stealth in space!

I think space combat will be more akin to predicting the path of a storm

I really like that analogy. I imagine there'd be a ton of statistics and AI assistance involved, to predict possible motion based on the ship class, its mission, the combat situation, previous experience with the same target, etc.

I really liked the combat in Peter F. Hamilton's Night's Dawn series. I think it might even be the first scene in the first novel where a freight squadron gets attacked by mercenaries. The combat in that universe tends to revolve around the vessels firing out 'wasps', little combat drones that themselves carry the weapons that actually do damage. The idea is that the wasps can get close enough using massive acceleration to target the enemy more precisely. (Of course, some wasps are just missiles, but others do actually carry secondary weapons.) Battles tended to become fights between clouds of wasps, as defensive wasps tried to stall the enemy's offensive wasps and vice versa, because the crewed vessels themselves were super-vulnerable.

Not sure how strictly realistic it was, but it seemed like it!

 

[chrispenycate]

Assuming we're limited to lightspeed communications and sensors, (which essentially limits us to interplanetary conflicts, no interstellar empires or whatever. Not entirely; we could be back to pre-flag sailing ship techniques, where the fastest way of sending a message beyond hailing distance was to seal it in an envelope and send a vessel), I suspect the main technique will be self guided weapons; either suicidal artificial intelligences (as in present day infra-red seeker missiles) or near suicidal biological intelligences (as in present day fighter-bomber pilots, with the odds of survival much lower). Assuming ships have to be built lightweight to achieve acceptable acceleration rates (if armour gives you a near invulnerable ship with a ten-thousandth of a gee acceleration, your predictive software is going to get very accurate, and something – what ever stretches the 'near' of its invulnerability – is going to be targeted on it very early in the battle) overwhelming their defences with kinetic strikes (see the cannonballs in Harry Harrison's 'Homeworld", if I remember correctly; cheap, literally throwaway weapons) might be effective, but basically beam weapons (Lasers, masers, plasma, particle beams) only become useful at knife-fighting range.

What do you consider 'relitivistic' velocities? I generally use the term for speeds where spacetime distortion means you can no longer trust calculations based on Newtonian physics, ie above, say, 90%c. While 0.1c might be a reasonable limit for a capital ship (although this would stretch battles into days, if not months, and the main tactical aim would be to get within threat range of your enemies non-mobile bases, planets, habitats or asteroid bases, so you can offer genocide in exchange for surrender), a simple linear accelerator (think of a rail gun with a fighter plane with one aimable warhead) would be able to throw weapons twice that speed, or more.

So the problem becomes one of confusing the attacking forces – chaff, EMP, stealth on the main ships, electronic simulations – while getting the maximum of information for your front liners. And using your beam weapons, and anti-missile missiles, and local fighters, and close kinetic weapons, fired from the same railguns as your attack wave, to defend you from the missiles and kamikaze pilots who were not confused.

Actual drive techniques modify the exact details, of course, but consider that anything that could accelerate a multi-megaton spacecraft at a tenth of a gee is putting out as much energy as a hydrogen bomb, and doing it continuously; it could well be that slowing down towards your enemy (turning your back on them) could be considerably more effective, both in attack and defence, that rushing towards them headlong.

 

[Vertigo]

There are a few things to consider on the speed front. For example speed doesn't just mean you have little time to react and you have to predict positions based on trajectories, but it also means that if the opposing ships/fleets are travelling towards each other the window of opportunity for fighting will be extremely brief (you will pass so fast) and also the turn around time for another pass will be huge. Each ship/fleet will have to kill all it's forward speed and begin accelerating back towards the opposing ship/fleet. Unless you have an as yet unknown technology such as David Weber's 'inertial compensators', this could means days or even weeks between each pass in the battle! This as Rodders mentions is something dealt with quite thoroughly in Jack Campbell's Lost Fleet series.

Another aspect that I thought of recently, though I haven't done the figures, is what happens in an orbital battle. IE. one taking place in orbit around a planet. Any change in velocity here, in other words any change in your orbital speed, will result in a change in your orbit. I'm not sure how big this effect would be but essentially a sudden acceleration in the direction of your orbit would result in your ship going up and conversely a deceleration would result in your ship dropping.

As I say I've not considered the actual figures so I don't know how big the effect would be but it seems like it might offer an interesting dodging manoeuvre. Also if you are in the same orbit as another ship and wanted to catch up to engage you would need to accelerate slightly down towards the planet, and keep doing so, otherwise your higher catch up speed would result in your orbit getting larger and you will overfly the other ship, with the risk of it getting a shot at your underbelly.

Personally I would go with Chrispy; the most likely weapons would be smart missiles that can accelerate much faster than a human body could stand and that would make final targeting decisions only when very close to the enemy ship. This is something addressed in almost painful detail in Weber's HH books.

 

[Fishbowl Helmet]

I suspect the main technique will be self guided weapons...

I disagree only because of the ranges and speeds involved. Up close, sure, they'd be useful. But not the main technique. They offer no benefit over weaponized lasers, which we basically have now, and are theoretically spectacular to use as weapons.

What do you consider 'relitivistic' velocities? I generally use the term for speeds where spacetime distortion means you can no longer trust calculations based on Newtonian physics, ie above, say, 90%c.

I'm no physicist, so I rely on Wikipedia's answer to that, i.e. "The boundary for when a particle becomes relativistic is difficult to define, but a particle can generally be said to be relativistic when Newtonian Mechanics no longer provide an accurate description which, within a margin of error of 1%, is 10% of the speed of light." Which is why I set the speeds where I did, roughly 5% c.

While 0.1c might be a reasonable limit for a capital ship (although this would stretch battles into days, if not months,

Not so sure about that. Lasers do defuse over space and time. There's got to be a limit to their effective range. Besides, no commander would want to fire a weapon and wait hours, much less days before knowing if it hit, and whether the enemy retaliated.

and the main tactical aim would be to get within threat range of your enemies non-mobile bases, planets, habitats or asteroid bases, so you can offer genocide in exchange for surrender), a simple linear accelerator (think of a rail gun with a fighter plane with one aimable warhead) would be able to throw weapons twice that speed, or more.

But wouldn't something like the Geneva Convention exist after a time? Agreeing that even if groups go to war, sending a rock down a gravity well would be akin to terrorism or a weapon of mass destruction (as in verbotten).

So the problem becomes one of confusing the attacking forces – chaff, EMP, stealth on the main ships, electronic simulations – while getting the maximum of information for your front liners. And using your beam weapons, and anti-missile missiles, and local fighters, and close kinetic weapons, fired from the same railguns as your attack wave, to defend you from the missiles and kamikaze pilots who were not confused.

Agreed, save stealth, which is impossible for anything that's accelerating or the source of weapons fire, etc.

Actual drive techniques modify the exact details, of course, but consider that anything that could accelerate a multi-megaton spacecraft at a tenth of a gee is putting out as much energy as a hydrogen bomb, and doing it continuously; it could well be that slowing down towards your enemy (turning your back on them) could be considerably more effective, both in attack and defence, that rushing towards them headlong.

Right, but such a drive would be visible in the next solar system and easily countered, and getting close enough to try to "braking fire" at a target would make you a sitting duck for all their toys. The predictive computer simulations would know exactly where and when the ship would be, making it as simple as a press of a button to destroy it.

 

[chrispenycate]

But a 'smart' missile - or one with a human pilot not too worried about survival, and history has shown that humans like that can be found, or generated – could take hours, or even days in ballistic mode, practically indetectable until it lit up a manoeuvring drive; and if nine tenths of what you sent out with your railgun (Ugh, Laithwaite would have hated the name, no matter how much he approved of the principle) was inert matter, using defensive weapons on every little radar blip would be an expensive operation.

Lasers in vacuum spread very little – seconds of arc –but they've got quite noticeable inconveniences as main weapons. The first is that spacecraft are designed to withstand quite high levels of ambient radiant energy. If not actually mirror plated (and I suspect warships would be) they are at least high albedo, which means that a large percentage of the laser beam is reflected off. If they are rotating to simulate gravity, and have something like a superconducting web to equalise temperature over the hull, burning a hole in one requires a massive overkill factor. So, pulse lasers; a hundred gigawatt hours of energy packed into a nanosecond, then wait for everything to cool down (and probably replace the half silvered mirror) before the next shot. And a few kilograms of mirrorplast outside the hull can absorb, diffuse (not defuse) and reflect the shot.

And, at the other end, we meet efficiency limits. Oh, it probably won't be like the SpectraPhysics Laser I toured (10 kW electric power for 4 watts of light – and you could light a cigarette on stage from the outer rim of a stadium) but you'll be lucky to get 50% efficiency; which means disposing of all that thermal energy. I'm assuming you can generate (and store) enough energy in the first place; bomb pumped lasers, while theoretically possible, are not convenient shipboard weapons.

Explosive weapons; conventional nuclear warheads, fragmentation devices and the like, are even shorter range, but don't need to be operated from a ship. If they can recognise a target and rush in and hug it, problem solved. But the closer they get, the more likely they are to be detected, and having all that unstable energy aboard they're far too easy to destroy.

Antimatter weapons? We can make antimatter. An antimatter fragmentation grenade, with microscopic bits too small to detect, but still each containing more energy than the Bikini explosion? Still, transporting and delivery systems are a bit beyond me.

Right, but such a drive would be visible in the next solar system and easily countered, and getting close enough to try to "braking fire" at a target would make you a sitting duck for all their toys.

It would only be visible next door after the light had time to arrive. Yes, shortish range (unless you could manage a photon drive, the most efficient system there can be), because the drive energy is not collimated and concentrated, but at a thousand times the energy of the incoming beams, not so negligible. And which toys? There would be enough matter in the propulsion beam (very high velocity reaction mass) that your beams wouldn't have a hope of burning through it, and missiles would have to fly off well to the sides, increasing travel time and vulnerability period. Not an option in the Honorverse, where they use gravitational drives (which also gives us our inertial compensators, by the way) but you're looking at an essentially Newtonian, action/reaction scenario.

I was assuming a real war; and do you have any doubt what would happen to the Geneva convention (and Geneva, and me) if it became a question of survival, rather than a gentlemen's game? I suppose if the two fleets originated on one planet it might get a bit inconvenient to sterilise it; but if they were different species, adapted to different environments…

 

[Vertigo]

I very definitely agree with Chrispy on the weapons. Laser weapons are simply too easy to defend against unless they are seriously high powered and, I suspect, to get them powerful enough to do get past any such mirror defense would require bomb pumped lasers, which, as Chrispy says, really wouldn't be too clever to operate from your main ship. Even if you do, the distances involved (as described by FH in the OP) would mean a significant delay between firing at and hitting (or missing) your target. Continuously making random course shifts should be enough to make a hit a matter of pure luck.

Alternatively, fire a load of smart missiles into the general area the enemy is expected to be in by the time they arrive. Fire them with a railgun so most of their trajectory is ballistic making them extremely difficult to detect. Don't fire their drives until they are close enough to pick their target with little time for that target to dodge. Using the drives the smart missile gets close enough to either destroy the target using a fragmentation bomb or a bomb pumped laser.

Another possibility would be to adapt the old grapeshot technique. A mass of inert, probably mettalic, projectiles fired by railgun to give them lots of kinetic energy. Then literally fill the approcimate area you predict the enemy to be with this 'grapeshot'. This would require much more significant random dodging from the enemy.

 

[Metryq]

From the discussion, it sounds like space warfare would be exceedingly difficult—at least with the technology we currently have, or can imagine. Naturally, a revolution in physics might come along (like the GENESIS MACHINE in James. P. Hogan's novel).

We no longer use battle lines of soldiers, like the musketeers of the 1600s and 1700s, nor are castles viable defenses. Most space battles I've seen in the movies or read in books are terrestrial tactics and weapon variations translated to the new environment—where they probably would not work too well, or at all.

What would space combat really be like? That may take some serious thinking outside the box. And is there some asymptotic limit beyond which warfare is absurd—that the technologies and resources required outweigh whatever resources might be gained?

 

[Vertigo]

Actually Metryq, if I'm brutally honest, I'm with your last point. I actually suspect space warfare might be so difficult to be almost impossible.

Another thing to consider that also goes in favour of the smart missile approach is to consider where warfare is headed today. Still a long way to go, but a lot of the most significant weapons research now is in the area of drones and unmanned vehicles of all kinds. I think the most likely scenario would be that the manned vessels of each side would stand well back and the real battle would happen in the space between them. All the actual fighting being done by drones.

 

[Grunkins]

I agree, Vert. Unless a person is actually going somewhere there is no reason at all to put them on a space ship.

 

[Vertigo]

I would also add that I suspect when one side's drones break through the other will promply surrender otherwise their chance of survival would probably become diminishingly small.

 

[alchemist]

I would also add that I suspect when one side's drones break through the other will promply surrender otherwise their chance of survival would probably become diminishingly small.

I think that's where your beam weapons will come in. At close quarters, taking out munitions instead of ships, acting in milliseconds based on info from sensors on the ship.

Apart from that, I think it's mostly about swarms of drones and counter-drones.

 

[Fishbowl Helmet]

I have my doubts about drones though. They're just as easily countered as lasers are, apparently. A nuclear blast nearby and the electronics are fried. or have a drone with a nuke hang back and once your line is broken, blast 'em. All the drones are dead weight. Or any type of electronic countermeasures (ECM) and they're done.

If lasers, or other long range beam weapons for things to get close and personal, then we'd be talking about particle beam weapons and manned fighters again. If one nuke drone can take out whole swaths of enemy drones, they're not going to be relied on much. Maybe as smart mines, but not in a stand up fight. And that's to say nothing of directed EMPs.

 

[Vertigo]

The only effect the nuke would have would be its EMP. Military hardware is already getting well hardened against EMP and anything designed to operate in space has to be well shielded from radiation anyway. I think it's reasonable to assume all military hardware will be protected against EMP by the time we start shooting at each other in space. If not then space warfare is pretty much out of the question as an EMP wouldn't just take out the drones it would take out all the spaceships in the battle, friend and foe alike.

Other than that, unless the nuke is seriously close to it's target it's going to have no effect whatsoever. Even fragmentation will only really be effective if it is close.

 

[Bakerman]

Actually Metryq, if I'm brutally honest, I'm with your last point. I actually suspect space warfare might be so difficult to be almost impossible.

I hate to take the pessimistic view, but if you have people travelling in space, and people disagreeing with each other, I think some form of space warfare is inevitable. Maybe not the battle-lines and national armies sort of warfare, but it will be there. Once you have any significant amount of industry or transit in space, it becomes a target for sabotage, terrorism or outright conflict. Once that is a possibility, you start to defend your assets in whatever way you can. Once assets are defended, you need more offensive capability to take them out, and that's the way the cookie crumbles. I'd really like to imagine a future where we really can just all be adults and get along, but all it takes is one person with a big stick to cause a lot of damage.

 

[Jacob Larch]

From a diet of Star Trek and Star Wars as a child I was surprised to come across a pocket sized gem in the form of "the outcasts of heaven's belt" in which a system from a world across the way comes to visit a developed, militaristic but xenophobic culture, meets a few people, adopts a disabled brother / sister scavenging unit (I'll give a nod to Joan here, that influenced my first book) and then escaped.

But instead of "blasting out of Mos Eisley" I was treated to one of the most dramatic slow-burn chapters I can ever remember with her description of space combat based on relative vectors, range of weapons, and the speed of communications being faster than the speed of missiles.

So you have the escaping ship A that has to pass by point B to reach escape point C on a parabolic vector. Due to the nature of space travel, plotted vectors do not allow for course changes on a nickel, or dog-fighting / evasive maneuvers of any kind.

The intercepting ship D has to travel to point E to launch missiles within something like a 30 second vector for the missiles to travel to point B and coincide their arrival with escaping ship A. Once the escaping ship reaches point C, it's too late: D can't re-plot a vector quickly enough.

Problem is, it takes minutes for D to reach E, but both vessels can communicate.

So you have an original chase where the escapees in A can see their death coming a mile away and they can't escape it, so they have to try and negotiate with the Captain of D to see the humanitarian side of their argument and "not launch". As the Captain of D enters E, time is ticking down and his finger is literally over the launch button whilst he makes up his mind....

 

[Kylara]

That sounds like a pretty ingenious solution to the plotting trajectories and all that...personally I think it would, most likely, end up as having tiny space UAV style ships, a bit like the wasps in PFH's work, but with pilots remote controlling them; humans tend to go with the close combat fighting if you look at weapon evolution, handguns are still in wide use and there aren't that many snipers about (but the reason for that is partly a different story I won't go into now) we seem to like being able to get up close and personal as we deal death out to the lackeys on the other side. So small speedy space UAVs made up of propulsion and weapons, flown by a pilot in a little pod on the big (FTL?) ship, fighting other little space UAVs flown by pilots in a little pod on the enemy ship...then, depending on whether you are winning or not, you can fly away slowly (or "hyperspace" jump or whatever) or send in a load of bombs - once their little kamikaze style space UAVs are nearly gone - to kill the big ship (probably fairly easy as we tend to build weapons first then, when someone steals them go *Oh s***, we should've thought about a shield that would defend against them FIRST, duh"), or maybe: you've got all their ships, so you have "won" *shakes hand and carries on*...then again we may not like the idea that we're not killing actual people, just machines, and send a squad over to the opposing ship to destroy some integral systems so that they are stranded and they all starve to death...

 

[Kylara]

Jacob, you said comms were still open right? So let us move into the evil computing world, if comms are open, then if you write a suitably impressive worm/virus/programme then you could simply encode it into your comms, aand render the ship incapable, thus allowing you to float over and kick it. Or just leave it and its occupants to die in the hostility of space, but now I'm giving my SF novel plans away *wink*