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[Sir Pseudonymous]

You know, they've actually developed prototype artillery shells than can adjust their trajectory in flight to compensate for any wind conditions or drag that's making them deviate from the desired course? (I remember seeing a thing about that on one of those "UNGH FUCK YEAH HIGH TECH WEAPONS AND SHIT UNGH" that were popular on discovery and the like before they started just spamming reality shows about fishermen and rednecks driving trucks for god knows what reason.) That's a guided projectile, but is certainly not what in common parlance is referred to as a "missile".

If you're talking about the ones I am thinking of, they use flanges/fins to guide the shell through the air to correct their course very slightly. You don't have that option in space, all course corrections require active energy expenditure unless you're in a super thick nebulae or something I guess.

But it is an example of a guided projectile that's not, in common parlance, a "missile," as well as a guided projectile that receives all its propulsion from the initial launch. While obviously an atmospheric solution wouldn't work in a vacuum, the basic concept remains the same. Slight corrections en route to account for any possible change in trajectory the target might make, as well as the margin of error in the sensors and targeting equipment.

A drone that carried its own guidance software and had no link to the outside world wouldn't be very susceptible to jamming, and if launched at a significant fraction of the speed of light to start with, only making small adjustments en route to its destination, there's not much room for any countermeasures to be deployed in time to matter. By the time its seen, it's already right on target, and launching chaff or something wouldn't change that (or even be outside the hull by the time it impacts). A single rocket taking down a multi-billion dollar vessel? Seems perfectly cheap to me, even if the guidance systems were made by contractors and so ran into the tens of thousands of dollars per shot. If it hits, it hits, and if it hits hard enough to bring down the target, it's more than payed for itself.

Missiles carry their own guidance software and sensors and they're susceptible to jamming and countermeasures. Barring magic stealth technology, the target ship would see the drone at the same time the drone saw the target. I have no idea what kind of electronic countermeasures would be available but I'm certain they would attempt to deploy them.

A tiny drone traveling very, very fast is going to be harder to spot that a big ship, which you already have the position of. Hell, something like this could be launched from a cold platform in distant orbit (or launched on a set trajectory towards another target), that has nothing but a single processor waiting for a wake up signal, where it goes hot, acquires the target and crunches the trajectory numbers, before firing several projectiles at it within a second. There would be no time to respond to it.

And missiles, for the most part, rely on GPS to reach their location. If it relied entirely on its own visual sensors to follow the target, there'd be nothing to jam with any manner of ECM, and the only solution would to somehow shake its visual lock. When you have the span of half a second to do this, even if done immediately on detection any sort of decoy for it to lock onto wouldn't even be out of your hull before it hit you.

And remember, the faster the 'drone' is traveling the tighter its possible intercept cone is, as it can only alter its trajectory so far from the original course in the time between sighting the target and impact/miss. Once it misses, it is lost for all intents and purposes as I doubt it would carry energy reserves to reverse course, that would take quite a bit of power and time. This is another reason I think it would be more correctly classified as a smart missile, but what we call it doesn't really matter.

Right, so long as that cone is larger than the target's cone of trajectory, it's still going to find its way on target.

[Nivim]

 So, here's a bunch of much longer and more detailed threads on this subject of space battles. Some▬ just a few▬ of those posting there even know what they're talking about, being enthusiasts and having to deal with the topic so much.
 "Weapons and mounts"
 "Weapon types and Gameplay"
 "Levels of Firepower"
 "Realistic Sword&Shield Thread" (Automatically scrolled down.)

[Shade-o]

I don't know if you know, but that also includes things like shields and FTL.

I also doubt that space warfare will be governed by balancing to ensure as fun an experience as possible by all factions and tech paths.

[Nivim]

 Of course not, but there isn't any difference between how ridiculous those threads are and how ridiculous this thread is.

[thobal]

Do you guys know anything about the theory around volume engagements. It's pretty basic stuff.

A projectile takes time to move from its launch point to its target. The target can move a certain distance in this time. It's a relatively simple matter to calculate the maximum volume the target could exist inside in the time it takes to cover the distance between the launch point and the target.

From there, it's simply a matter of filling this volume of space with a destructive density of projectiles. Given the energy requirements involved with propelling any sort of large object at high speeds in environments with little or no grasping medium, any sort of combat in space is going to be fairly short and typically weighted heavily on the side of the defender.

Most combat will be waged with dumb rocks. All this talk of missiles, fighters and drones is utterly fantastic. Any war in space will quickly devolve to  two planets and whatever colonies they have throwing rocks at each other. It's not very romantic and it's not fun to write about. It's the same reason no one writes many novels or screenplays about nuclear war.

tl;dr
I'm sorry, but you're all very very wrong.

[Soadreqm]

But what if you don't want to destroy the planet? Humans have had nukes since World War two, but very few wars are solved with them. Sure, you could just detonate the enemy's planet, but then he'll detonate your planet. It is so much better to just use your planet detonation capacity to lend weight to your requests for ceasefire, and solve things with diplomacy. Have a few proxy wars to show them who's boss.

And while high-speed rocks are great for utterly demolishing stationary ballistic targets like planets, they're not so great against things that can change direction. Your rocks do not have any kind of guidance system. They follow completely deterministic ballistic paths. I can take my huge-ass futuristic infra-red telescope, notice them coming MONTHS before they hit, calculate with perfect precision which points of space they are going to occupy at each moment in time, and dodge. Maneuvering uses fuel, so just having to move out of the way is a loss to me, but you're not going to actually hit anything. Now, a guided missile with a warhead can alter its course depending on where I'm moving, and only has to get reasonably close and explode to kill me.

[thobal]

Yes, but unless you're assuming some fantastically advanced propulsion system, you cant maneuver very far and expect to ever get back on course. Plus the rocks would presumably be launched not with rockets but mass drivers at tremendous speeds. A cloud of rocks traveling one tenth of one percent of light speed could go from the moon to Mars in less than three days. I admit that that speed does seem fairly high (~300km/s).

While it's true that a spacecraft could maneuver to avoid the rock cloud, it's options are not unlimited, and most people's understanding of the ease at which spacecraft can maneuver is extremely exaggerated.

These rocks would also be capable of striking specific cities, the entire bio-sphere need not be wrecked.


It is true that nuclear weapons have eliminated most wars. Must I remind you that major fleet actions have also been eliminated?



War in space will be a matter of sneak attacks, commando actions, and tense standoffs. There will be no huge battles with giant fleets shooting at each other inside visual range.

Wars fought in space promise to be of the cold variety. I cant imagine a proxy war possibly emerging except perhaps in the cold outer orbits.




I have just had an idea for a kind of spacecraft for battle. It would be huge, hundreds of kilometers in size, composed mostly of solar concentrators, panels, and dozens of nuclear reactors, capacitor banks, automated all to hell. Basically it would have to boil anything that came at it into vapor. Missile, drone, whatever. Huge radars, telescopes, and the like.

[USEC_OFFICER]

Most combat will be waged with dumb rocks. All this talk of missiles, fighters and drones is utterly fantastic. Any war in space will quickly devolve to  two planets and whatever colonies they have throwing rocks at each other. It's not very romantic and it's not fun to write about. It's the same reason no one writes many novels or screenplays about nuclear war.

Really? I'm fine with the idea that waring planets will chuck rocks at each other as a type of bombardment, but I doubt that all the two planets would do is chuck rocks at each other. If they did, it would be so simple to just send a ship around in a circular course to attack the facilities that are launching these rocks.

Additionally, if these two planets are not even in the same system, then the rocks would be worthless, since it would be simple to place detectors at the edge or beyond the system, then calculate the asteroid's movement and figure out whether its a danger or not. If it is going to impact an important planet, then send your mass drivers to intercept and redirect it/destroy it. Since the rock can't change position, a planet can train power lasers on it to destroy it. If you are well prepared, it's quite simple. This is assuming that war between two systems could occur. With the several year delay between communications, and the incredibly long travel times, it would be almost impossible for war to occur. And if it did, there would be enough time to prepare the anti-asteroid defences. (Unless the enemy acted sneaky and declared war when their asteroids were due to hit the enemy planet.)

If the two waring planets are in the same system, then bombarding each other with asteroids becomes even more useless. The two planets will simply send space marines to disrupt the enemy's attempts at bombardment, while trying to protect their own attempts. Fleets could be built to hover over the enemy's planet to prevent them from sending the necessary men and equipment from reaching the asteroid belts. If a war reaches a point were rock bombardment is used regularly, then the war is pretty much won.

Inter-system warfare would be based around preventing the enemy from bombarding your planets with rocks. At first this means sending space marines to attack enemy facilities in asteroid belts, before it evolves into fleet warfare. As soon as one fleet is victorious, then a blockade of the enemy's planets can commence. Now the enemy has no way of attacking you (Since they can't get off their planet without getting blown up.) and you can launch rocks at your leisure.

[Soadreqm]

While it's true that a spacecraft could maneuver to avoid the rock cloud, it's options are not unlimited, and most people's understanding of the ease at which spacecraft can maneuver is extremely exaggerated.

It doesn't have to maneuver far. Assume a spherical rock one meter in diameter, on a course towards a head-on collision with a spherical spaceship a hundred meters in diameter. After the ship notices the rock, it will have to move fifty and a half meters into any direction perpendicular to the rock, in the time the rock is in travel. Now, this is a spaceship, presumably capable of crossing interstellar distances in a somewhat reasonable time, so you'd expect it to have some VERY IMPRESSIVE thrusters. And you're not going to get much of a cloud in space. If you wanted to force the ship to dodge, say, a thousand kilometers, you'd need to completely fill a circle two thousand kilometers in diameter with rocks. That's about (pi*1000000^2)/(pi*50^2) = 400 000 000 rocks. Well, a bit less since the rocks have volume too.

If we're launching granite boulders one meter wide, it'll take 9.8×10^12 J of energy to accelerate four hundred million of them to 0.001c. If a battleship weighting 100 000 000 kg was to do that, it'd gain the velocity of 313 m/s, allowing it to clear the danger area in fifty three minutes. In fifty three minutes, a 0.001c rock will travel 953000 km, which is a pretty dangerously short range in space.

Okay, I have no idea what a futuristic spaceship would weight. It could be something like a hundred thousand tons. That was the smallest ship you could build in Space Empires IV.

Also, I'm not saying that the future of space warfare is going to involve huge battles with ships shooting at each other at close range. Only that rocks aren't going to be great for fighting anything nimbler than a space station in orbit.

[Urist Imiknorris]

One would think lasers would be useful in space combat. Not as they're portrayed, of course, save for that one episode of TNG where the Enterprise makes first contact with the Borg (and the latter take a piece out of the ship with a cutting laser or similar device). Severing vital components would probably lead to a quick victory with other weapons (like the aforementioned rocks).

[forsaken1111]

One would think lasers would be useful in space combat. Not as they're portrayed, of course, save for that one episode of TNG where the Enterprise makes first contact with the Borg (and the latter take a piece out of the ship with a cutting laser or similar device). Severing vital components would probably lead to a quick victory with other weapons (like the aforementioned rocks).

Speaking of, I really enjoyed the game Nexus. The laser weaponry in that game barely did any hull damage but could pierce shields and armor to damage and destroy subsystems. Shields reduced the laser's power but a sufficiently strong beam could penetrate.

[Strange guy]

Seeing the vast distances it seems like stopping your fire from being dodged will be a big issue. Lasers have speed, missiles/drones/fighters can change course but everything else could be mostly redundant. I suppose if you fire enough shots or they explode violently enough it could work, but in that case you might as well just turn them into missiles.

Kinetic weaponry is the obvious answer for attacking planets. So do people think it will be stray asteroids or 'rods from god' dominating the kinetic weaponry? Since you can pick them up near the planet you don't have to worry about carrying asteroids around across large (by interstellar standards), but it raises the question of how exactly you direct them. There's also a potential of being less controllable and predicable, so might not be great if you are avoiding unnecessary ecological and collateral damage, though it's not like either is great for that.

[PTTG??]

Why would two planets fight? We have to consider this, because if, for instance, Mars wants to take some of Earth's biomass, then they presumbably don't want to vaporize it.

Furthermore, let's not be so close-minded that we forget that it's not just "planets" that will be political entities.

Consider instead of warring planets, three or five or a dozen factional groups of miners in the asteroid belt. Of course, when you picture this, remember that the belt is so sparse as to make virtually every stone invisible to all others. What sort of combat would we see in that sort of situation, then?

Or perhaps we have colonists arriving at mars whom, for whatever reason, are not welcomed by the current settlers. How would they fight in that case?

[forsaken1111]

Oh no, we were accidentally discriminatory against hypothetical asteroid dwellers!

For some reason that just strikes me as funny.

[thobal]

...if these two planets are not even in the same system...

...presumably capable of crossing interstellar distances in a somewhat reasonable time... some VERY IMPRESSIVE thrusters...

That completely absurd.

 Do you have any idea the amount of energy you'd need to move anything an interstellar distance? The sheer impossibility of getting from star to star in anything less than hundreds of years? The spacecraft would be huge. Even allowing for advanced electrical propulsion(500 GJ/kilogram), your 100,000,000 kilo ship will need 90,000,000,000 kilos of propellant to reach .10c.  I dont think that's accounting for relativistic effects. No, interstellar wars are impossible.

Taking your hundred million kilo ship again. To execute the dodge you suggested, it would expend 196 kilos of propellant(assuming again, hypothetical electric propulsion). Suddenly 100,000,000 kilos is 99,999,804 kilos. So we must question how much of the ship is fuel? What is the maneuvering capability of this ship? If the ship wanted to reach the sun's closest neighbor(not allowing for any sort of braking maneuver, just to pass by) in 45 years with a starting mass of 100,000,000 kilos, only 10,000 kilos or so are going to make it to the next star.

tl;dr
You hundred thousand ton spacecraft launches towards Alpha Centauri at 10% of light speed. When it arrives 45 years later it is still traveling at 10% of light speed but is out of fuel. It masses at about ten tons, roughly the equivalent of two Apollo Command Modules.




 
About the amount of rocks needed to make a hit:

You don't need to fill the maneuver radius completely.One can leave all the gaps they want so long as no gap exceeds the size of the target(allowing a modest margin for the destruction of incoming projectiles and the spacecraft's ability to quickly dodge into gaps and target incoming).

Plus, one need not fire just one volley. I think it would be interesting to calculate how long a body like, oh say, the Moon could keep up that kind of defense before the lost mass began to effecting it's relationship with the Earth.




If you can see my cold rocks then I can see your warm troop transports. Hiding from thermal signatures against a 3 kelvin background doesn't seem very plausible. Supposedly, off-the-shelf(current technology) sensors could detect the space shuttle's heat signature from Pluto.

Or perhaps we have colonists arriving at mars whom, for whatever reason, are not welcomed by the current settlers. How would they fight in that case?

I like this one though, realistic. Though local martians would probably want the manual labor, assuming they were unhappy, I'd say:

Rovers filled with seismic survey charges parked in front of important buildings, snipers, sabotage, biological warfare. Knife attacks, sticks, stones, whatever they found handy. Crude landmines in well traveled areas.

Now that would make an interesting movie. An insurgency of Martian born settlers who think the new arrivals are there to steal their destiny.



But as for the asteroids, only Ceres and a few others have the sort of mass you'd want in a combat situation. I'm sure any disputes could be easily settled by calculating the amount of mass both parties had on hand and would be able to throw and simply declaring a victor without getting the universe all entropic. I think if the belt is independent(good luck with that), then Ceres would be master. Who ever held that would have the biggest rock and the deepest foxhole.