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Space naval combat (Segway from Antimatter thread)

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Tue, 2010-08-17 18:26
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Rhyx Rhyx's picture
Space naval combat (Segway from Antimatter thread)
I thought that the possibilities of this topic deserved it's own thread so here it is. Quoted form Arenamontanus :
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Thinking a bit about naval strategy: What kind of weapons are being fielded, can they be defended against, and what kind of missions will the ship be sent on? If the weapons are hard to defend against the ship has to be stealthy and hard to hit. Looking at the core book description of the destroyer having railguns, nuclear and HE missiles, point defense lasers and fighters, tells us a few things: Railgun projectiles currently move with velocities a few kilometres per second. This is comparable to normal inter-spacecraft velocity differences: just putting a pebble in the way of your enemy will do plenty of damage on its own. It also means that it will be hard to hit an enemy that is manoeuvring since by the time the projectile reaches where it was, it will have had plenty of time to go somewhere else. Even spamming space with a cloud will be hard since the volume where the ship could go is very large. If the distance to the enemy is d, it moves with velocity v like the projectiles and can accelerate up to a km/s^2, then the total volume where it could go is .5*pi*a^3*d^6/(3*v^6) - for d=1000 km, v=10 km/s and a=5 G I get a volume of 62 million km^3. [I assume the projectile traverses the distance in time d/v, during which the enemy has accelerated up to .5*a*(d/v)^2 away from the extrapolated path.] If railgun projectiles go much faster, then things cheer up for the attacker. A 100 km/s projectile gives the enemy ship just 62 km^3 to hide in, and a 1000 km/s projectile just 62,000 m^3 (and they are going to intersect the volume too, not just sample a single point). Increased acceleration tolerance of the enemy of course equalizes things a bit, but the deciding thing is the relative distance between the ships - you can't hit anybody beyond a certain radius - and the speed of the railgun projectiles. Note that habitats are sitting ducks here, possible to hit almost from anywhere with a high-accuracy shot. The probability of hitting a ship with cross-section area A will be ~4*v^4*A/(pi*d^4*a^2). [I assume the projectile will hit somewhere in a circular cross section of area pi*(.5*a*(d/v)^2)^2, and if it hits within a particular area A it hits. ] Assuming A=0.1x0.1 km for an impressive Destroyer, with the above 10 km/s projectile the chance to hit is just 10^-8. For 100 km/s it is 0.0005, and for 1000 km/s you are pretty certain to hit. If the ship is just 10x10 meters, then even the superfast projectile is back at 5% chance again. This makes fighters sensible - they can likely keep a small cross section and high acceleration. Also note that if the distance is just 100 km the hit chance goes up a lot - you want to shoot close to the enemy, but not be close to him. The kinetic energy from a 10 km/s 1 kg impact is 50 MJ. At this point the kinetic energy starts to become bigger than any (chemically) explosive force you can put in the projectile. 100 km/s is 5 GJ (about one ton of TNT) and 1000 km/s is 500 GJ (100 tons of TNT). They will penetrate to a distance about equal to the projectile length times the ratio of projectile to armour density (Newton's penetration law). This is actually an interesting problem: you want to deposit all this energy inside the ship, so you want to tune the projectile length to its armour. Too heavy projectiles and they go straight through the ship - sometimes having no armour at all the smart strategy (just hope they do not hit your antimatter). Too light projectiles and all energy gets deposited outside the armour. Since the lasers are point defences rather than main armaments (with v=300,000 km/s, you would be able to hit anybody visible within at least a lightsecond), I think we can deduce that it is hard to project a sufficiently high energy beam far enough, but that it can become tough on short distance. I expect railgun projectiles are hard to hit, but missiles are the likely main targets. Missiles can presumably accelerate at least a few 100 G. They can also adjust their course to get close to ship targets and then launch something nasty. However, they likely need to get reasonably close to do this given the above discussion. They likely lack the energy to launch railgun projectiles, but instead launch a bunch of warheads or fire a one-short laser. So they will always be vulnerable to point defences, which will successfully defend the ship if they disable the missile before it detonates. Conversely, if it detonates then it can deliver far more oomph to the enemy than a railgun projectile. There is essentially no way a ship can handle running into a point-blank nuclear fireball or piece of antimatter. Together, this seems to imply that 1. Missiles are the real ship killers, and much effort will go into detecting, avoiding and disabling enemy missiles. 2. railguns are useful against certain targets, but either require enormous velocity or rather short distance fighting. 3. Fighters make sense since you want to bring sensors, railguns and missiles close to the enemy while staying far away yourself. 4. Armour might mainly be against railgun impacts (and other debris) rather than missiles, and it might be better to have a ship that is resilient to a few impacts than have a heavy armour that brings down your acceleration. 5. Railguns make sense against fighters, since they can not accelerate as much as missiles but will be close to you. 6. Maintaining distance is a good way of avoiding to be hit. Hence, you want to be faster than your enemy (and stealthy). Second best is having a big acceleration, tied with a small area. If I were a naval planner for the Titanian Commonwealth or the Planetary Consortium, I would likely start by deciding that the major naval ships would not have any space for biomorphs onboard, and quite likely not much of synthmorphs either. The sheer amount of space and mass that has to be spent on keeping a biomorph alive is large, and they have to be protected from accelerations, temperature, radiation, you name it. An infomorph crew and tiny repair synthmorphs/nanoswarms would work much better. This way the ship could be made as stealthy as possible (by keeping a low temperature), as small as possible, and able to handle extreme accelerations. My idea for a major high-tech naval ship would probably be something like a tiny Borg cube, dropping off fighters and modules in a large cloud while staying hidden. Armour would be sacrificed for redundancy. The Jovian Junta, having to have biomorphs onboard, cannot do as heavy accelerations and will be forced to have bigger ships. So they can add lots of armour to withstand railgun fire, and lots of point defences plus sensors to catch any incoming missiles. To have a chance at hurting the enemy they need plenty of fighters, again pretty heavily armoured/defended since they cannot be too nimble (expendable pilots cannot fix the lack of acceleration tolerance: a pulped kamikaze pilot is useless). To my mind, that suggests that they would really want to get their long-distance weapons better: either very fast railguns, or *powerful* lasers. [doff's my admiral's hat folded from newspaper]
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Tue, 2010-08-17 18:35
root root's picture
Re: Space naval combat (Segway from Antimatter thread)
root@Space naval combat Hmm. Can we break this down one piece at a time? Let's start with how engagement would have to happen. This is based on sensors or intelligence, so that gives us an idea of how far away from each other the ships have to be before they can even start to engage.
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Tue, 2010-08-17 19:09
Rhyx Rhyx's picture
Re: Space naval combat (Segway from Antimatter thread)
My friend and I spend entirely too much time thinking about how war would be waged in outer space and basically this is what we came up with: It will probably be a mix of submarine and naval and air tactics. Here's what I mean. As anyone who's read the Hitchhiker's Guide knows: Space is big! ~So detection is the first key, because you can't shoot something if you can't see it. (Well you can try but bring a LOT of ammo.) ~The fastest means of discover something in space is light, or in this case infrared radiation. Meaning that hiding that IR is gonna be paramount in the same way sonar emissions and engine noise works in water. Problem is all that heat needs to go somewhere, it's gonna warm up awful fast in that ship if you trap all your heat. So depending on the situation it might be an endurance run. the guy who's heat sinks gives out first loses. ~Therefore you need detectors to see him before he sees you, that's where the fighters come in running a search pattern and looking for any IR leaks or anything else. Keep in mind that in an engagement both sides are doing this, so the fighters are gonna meet somewhere in the middle and duke it out in a furball. ~The fighters deployment will have to be very strategic because through little tricks of geometry and statistics your enemy can look at your fighter deployment and try to guesstimate where you are, same thing with him. ~Once you find him, the fighters converge and try to destroy the point defense lasers so that your battleship can finally evacuate it's heat and fire a nuke without it being shot down in mid flight. It hits. Game over. ~Or all your fighters get taken down by his and you are left a sitting duck slowly cooking in your own gravy until your coolant overloads and you either blow up, fry to death, or do an emergency heat dump and give away your position. Add to that electronic countermeasures, elecetronic counter countermeasures, reaper and fury boarding crews, decoys, Viral hacking and counterhacking, smart dust, various things to hide behind and it's a party!
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Tue, 2010-08-17 19:46
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
Yes, detection is the key. If you are accelerating you will be leaving a long trail of energetic hydrogen or plasma behind you, and this will have detectable black-body radiation. If we assume metallic hydrogen produce a mere 1000K, that is still 2898 nm IR radiation. A fusion torch is definitely hotter. Even worse, antimatter annihilation does not just produce the desired gammas, they also produce pions that decay while radiating neutrinos. This means that even if you hide your plasma tail, you will radiate a neutrino signature. Given EP tech, we know that they can be detected (but perhaps it is hard to get a good position from neutrinos, so the enemy will just know there is somebody out there but not exactly where). So ideally your ship should not accelerate during the battle. Or you try to hide yourself among decoys. Every time you manoeuvre, some decoys trigger and try to look like they are you. Generally, I expect space battles to involve extended networks of decoys, drones, munitions, sensors and whatnot. The communications issues are serious: I expect it to be worth the money to use FTL quantum communication to keep everything linked, untraceable, fast and unjammable. Qubits are a very strategic resource (incidentally, I doubt they can be stored without some very good nano - bad news for the Jovians, who probably have to break a few rules to get it). Primitive forces that have lightspeed-limited networks are at a serious disadvantage, and must also ensure that the enemy cannot detect *where* the cloud sends its messages (OTP encrypted neutrino broadcasts in all directions instead?) Active sensors are a dead give-away of where you are, but you can always use an expendable buoy (and triangulation from dispersed sensors). Stealthing against radar/lidar/Xdar on all wavelengths is not going to be practical, so you better hope the enemy does not activate an active sensory buoy in the wrong wavelength band. BTW, an interesting fictional space naval engagement in this style is found in Scott Westerfeldt's novel "The Killing of Worlds" (the sequel to "The Risen Empire"; lots of fun EP-useful stuff in both). Most of the novel consists of two ships racing towards each other, launching enormous numbers of drones of different kinds, experiencing a second of battle, slowly turning around again, redeploying and finally having (if I remember right) a decisive battle lasting a second or two.
Rhyx wrote:
~The fighters deployment will have to be very strategic because through little tricks of geometry and statistics your enemy can look at your fighter deployment and try to guesstimate where you are, same thing with him.
It becomes a nice game of guessing. You know the deployment of the enemy, but also that he knows that you know and will hence place his important assets where you least expect it. Conversely, he wants to catch you, so he also has to deploy fighters where he thinks they will have a chance to find you. Sounds like just the kind of probabilistic multidimensional differential game AIs like to play.
Quote:
~Once you find him, the fighters converge and try to destroy the point defense lasers so that your battleship can finally evacuate it's heat and fire a nuke without it being shot down in mid flight. It hits. Game over.
Or you get enough of a hit that the stealth is permanently broken, and it hence becomes a sitting duck for a long-range sustained railgun attack. Of course, at that point it has nothing to lose in powering up completely and charging with everything. What happens depends on who the crew is.
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Tue, 2010-08-17 20:13
icekatze icekatze's picture
Re: Space naval combat (Segway from Antimatter thread)
hi hi Unfortunately for the fans of exciting naval warfare, space is just about the worst possible place to hide. Space really is big, as Rhyx says, but everyone is going to basically know where everyone else is before the fighting even starts. I'll start with some examples using modern technology, not super high tech stuff like in Eclipse Phase. • The destroyer as an example is putting out over 120 terrawatts when it uses it's main engines. The exhaust plume from which would be intense enough to see from Alpha Centauri with passive sensors. • The main engine on the space shuttle can be seen from Pluto. • The maneuvering thrusters on the space shuttle can be seen from the asteroid belt. Thanks to the unforgiving nature of physics in a vacuum, even if you shut off your engines and go dark, they'll still know what your course is from the last time you made any sort of burn. There's really no way to get around that unless you use some kind of reactionless drive. Even if you could sink your heat and got lucky with nobody looking in your general direction when you made your burn, you'd be devoting prohibitive amounts of space to heat sinks and you'd be taking much longer to reach your destination. Unless you are in a confined space, like in an orbit, there's no reason for any ship to get within weapons range of a piece of space junk, regardless of whether or not they have identified it as such, so laying in wait probably wont help much either. At least not in deep space, and not for an aggressor. ----- For the most part, space combat in Eclipse Phase seems to me like you will have two commanders who are part of opposing factions, they both look at the fleets arrayed against them and say "well ƒ£ßK that." Up until the point where they're replaced by someone a little more insane. At that point, the aggressor fleet burns towards their objective giving the defenders a few weeks/months to bolster their defense. The aggressors might open up from a long distance with bombardment of non-maneuvering targets with railguns. Workhorse craft could potentially maneuver defensive plates into the path of the projectiles or tug stations out of the way. Either way, the defensive fleet is going to be obliged to respond at some point. The two fleets might dance about at the edge of their effective weapons ranges for a while, hoping to score a lucky hit, but more likely they'll have to charge straight in for a joust. A joust is where the two sides burn towards each other making course adjustments from side to side to attempt to evade projectiles, all the while firing back. As the ranges get closer, the weapons become more effective and many times the attack will be over before the two pass by each other. Some weapons might have a long cooldown period, and those would be held in reserve as long as possible to give them the best chance of scoring a hit, but not so long that the ship is hit and disabled before they get a chance to fire. In a big messy joust with lots of vessels, command and control may break down due to jamming and other electronic warfare. Targeting may not be coordinated and some ships may survive the joust unharmed, at which point they turn around and repeat the process. Assuming they don't feel surrender or escape is the better option. That probably depends on the value of the target. In a minor naval engagement, fighters will probably be deployed to deal with a significantly smaller threat while leaving the mothership safe from reprisal. In a major naval engagement, I think that fighters will be deployed as either missile busses or missile point defense. In space, there's really not much difference between a fighter and a missile except that one has a chance of coming back. Because of that, it is required to devote extra space to propellant for the return trip, making it the less combat effective of the two. Of course, combat effective and cost effective don't always equal the same thing, should fighters have a sufficient survival rate.
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Tue, 2010-08-17 20:46
root root's picture
Re: Space naval combat (Segway from Antimatter thread)
root@Space naval combat Heat dispersal is interesting in a vacuum. Convection and conduction do next to nothing with little to no matter to interact with, so it's all down to radiation. So we are working with the equation: Q = εσAT[sup]4[/sup] Q = rate energy is emitted from a surface (W) ε = emissivity of the surface (0 ≤ ε ≤ 1.0 ) (unitless) σ = Boltzmann constant = 5.67[sup]-8[/sup] W/m[sup]2[/sup]K[sup]4[/sup] A = surface area m[sup]2[/sup] T = absolute temperature of surface (K[sup]4[/sup]) Making the only modifiable variables the emissivity and the surface area. Here is a random paper selected for it's ease of googling on an "amorphous diamond-like carbon/Ag-alloy", or a diamond/silver glass that has an emissivity of 0.1. We can assume an emissivity of that or lower. Our desired upper limit on temperature is going to be 2.7 K (the ambient temperature of space from background radiation), and lets assume 1 square meter for ease of calculation Q = 0.1*(2.7 K)[sup]4[/sup]*5.67[sup]-8[/sup]W/m[sup]2[/sup]K[sup]4[/sup]*1 m[sup]2[/sup] Q = 5x10[sup]-6[/sup] W (roughly) So you need to have less than 0.000005 W of energy transfer out of your ship to be invisible. Since that is impossible, I guess you have to just go with being far enough away that not many of the photons being put off actually get to them. Any better methods of thermal camouflage?
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Tue, 2010-08-17 20:57
icekatze icekatze's picture
Re: Space naval combat (Segway from Antimatter thread)
hi hi You could attempt to redirect your radiation in a single direction, actively refrigerating one side of your ship while extending radiators on the other. However, given the technology level, I think it is a safe assumption that anyone who has warships is going to have remote sensors all over the system, making it very difficult to point your thermal exhaust away from prying eyes.
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Tue, 2010-08-17 21:27
Rhyx Rhyx's picture
Re: Space naval combat (Segway from Antimatter thread)
Well darn, So trying to be subtle in space is like playing hide and go seek with a bunch of people wearing neon colors and bright yellow construction helmets. That kind of wizzes on that nice clautriphobic"Das Boot"-like dramatic feeling. Oh well we have no choice! Bring in the inflatable decoys! http://www.aerostar.com/military/military_decoys.htm
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Tue, 2010-08-17 21:42
icekatze icekatze's picture
Re: Space naval combat (Segway from Antimatter thread)
hi hi Decoys can be useful in some situations, but usually only as a last ditch effort to confuse a less intelligent guided weapon. In the grand scheme of things, they're not terribly useful. Movement in space follows action and reaction rather plainly. When you see a ship thrust, you can measure the velocity of it's exhaust, the vessel's change in velocity, and compare that to the intensity of it's exhaust, those three factors will tell you very precisely how much the vessel weighs. (Pro-tip, by measuring thrust and change in velocity, you can determine how much reaction mass a ship has left) In a nut shell, if you have a decoy that produces the same thrust as your vessel and it has less mass then your vessel, it will accelerate much faster. If you reduce it's thrust to keep it's acceleration the same as yours, it obviously puts out less energy. I don't know how fast a processor on the tip of a missile is going to be, but I suspect you would have to launch your decoys very late in the game in order to fool it. Additional: For fusion powered ships, a decoy is probably going to need a fusion reaction to generate a sufficiently bright heat signature. At that point though, you might just consider tossing fusion warheads out the side of your ship and vaporizing enemy missiles as they get within the kill zone. (I do believe you can shape charge nuclear explosions to some degree)
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Tue, 2010-08-17 22:07
root root's picture
Re: Space naval combat (Segway from Antimatter thread)
root@Space naval combat
icekatze wrote:
hi hi Decoys can be useful in some situations, but usually only as a last ditch effort to confuse a less intelligent guided weapon. In the grand scheme of things, they're not terribly useful. Movement in space follows action and reaction rather plainly. When you see a ship thrust, you can measure the velocity of it's exhaust, the vessel's change in velocity, and compare that to the intensity of it's exhaust, those three factors will tell you very precisely how much the vessel weighs. (Pro-tip, by measuring thrust and change in velocity, you can determine how much reaction mass a ship has left) In a nut shell, if you have a decoy that produces the same thrust as your vessel and it has less mass then your vessel, it will accelerate much faster. If you reduce it's thrust to keep it's acceleration the same as yours, it obviously puts out less energy. I don't know how fast a processor on the tip of a missile is going to be, but I suspect you would have to launch your decoys very late in the game in order to fool it. Additional: For fusion powered ships, a decoy is probably going to need a fusion reaction to generate a sufficiently bright heat signature. At that point though, you might just consider tossing fusion warheads out the side of your ship and vaporizing enemy missiles as they get within the kill zone. (I do believe you can shape charge nuclear explosions to some degree)
"How far away do you have to be before the heat and light diffuse to much to be picked up by current sensors? I imagine that if we up the scale by one, the heliopause probably occludes a great deal of energy. Other than a heliopause, wouldn't seeding your combat zone with ice crystals and prisms be a good idea? I guess you aren't seeding your combat zone as much as your combat vector, but you should be able to cover a decent area in the cone in front of you."
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Wed, 2010-08-18 07:03
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
The atomic rocket site is filled with great information, and we should all read the page on sensors (especially since it rather accurately predicts a lot of this thread!): http://www.projectrho.com/rocket/rocket3w.html It changed my opinion about stealth in EP. I think it is indeed hard to do. A very useful formula is that the maximum range of detection of a cross-section area A ship at temperature T that is just coasting, is 13.4 * sqrt(A) * T^2 km. So the 100x100 m Destroyer is visible from 1.3 billion km away, even when at a cool 100 K. A 10x10 m fighter is visible over 13 million km away. Bad news, but now consider what happens when you try to shoot at it. Over those distances railgun projectiles and lasers are useless (as per my previous estimates). The projectiles will also be detectable (see below), so the ship will turn off its previous course. So you need to get something close to deliver damage, and that means missiles or fighters. Except that these are also visible. Rough railgun projectile temperature and detection estimate: when accelerating it to velocity v, .5*m*v^2 J of work are done. A fraction f (<<1 but >0) of this will turn into heat. The temperature becomes T=.5*f*v^2/C, where C is thermal capacity (~1000 J/K). If f=1% and v=10 km/s, we get bright 500K projectiles. For v=100 km/s f must be much less, since otherwise we would just get a vaporized mess. If f=10^-4 (a ridiculously good efficiency) the faster projectile will also be 500K. The only thing making them hard to see is their small area. Assuming the visible area is ~10x10 cm, then they can be detected 13.4*0.1*500 = 670 km away. That gives you 67, 6.7 or 0.67 seconds to point defence them. At least for projectiles slower than 100 km/s this is pretty OK for the defender. Fighting distances will be on the order of the distance where you can accurately predict where the enemy will be in order to hit him with something. For a ship with acceleration a, it can go .5*a*t^2 in time t from previous course. If your sensors and weapons are d km away, they will lag d/c seconds. You immediately respond and send something (laser or projectile) at velocity v towards the most likely next position. It arrives after d/v seconds. If the uncertainty distance is less than the size of the ship, you will have a good chance of hitting. So the condition for being able to hit someone is: sqrt(A) < .5*a*d^2*(1/c+1/v)^2, or d has to be less than sqrt(2 sqrt(A)/a(1/c+1/v)^2). Assuming a slowly accelerating big ship with a=5 g and sqrt(A)=100 m, the laser distance is 302,000 km. For a smaller 50 g fighter with sqrt(A)=10 m the distance is 30,000 km. For a missile with sqrt(A)=0.1 and 500 g acceleration point defences start having a chance at a distance of 957 km. Note that it is likely that the upper range here is more due to energy dissipation and diffraction limits than being able to paint targets. For slow railgun projectiles with v=10 km/s, the capital ship can be hit at 20 km distance and the fighter at 2 km. For mid-speed railguns you can hit the big ship at 201 km and the fighter at 20, and for 1000 km/s railguns you can hit at 2000/200 km. Railguns have shorter range (but presumably are much better at doing damage). So where does this leave us? Capital ships are easy to see and hit, but they are pretty deadly against fighters too (and vice versa). The point defence zone is about 1000 km in radius: inside it point defenses have a chance of hitting nearly anything. If you can get sensor drones really close to the enemy your effective firing distance increases without his improving, giving you a huge advantage. So I am strengthened in my view that the capital ships are more like carriers unleashing plenty of smaller crafts, drones, munitions and gadgets than traditional heavily armed battleships. The future probably belongs to the nanofighters.
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Wed, 2010-08-18 09:37
nezumi.hebereke nezumi.hebereke's picture
Re: Space naval combat (Segway from Antimatter thread)
Yes, fighters are visible - as long as they are active. If you have an infomorph in cold storage, with the fighter ejected from the carrier ship outside of range, and with no maneuvering and little or no power systems, you now have a pretty stealthy fighter. It'll be detected before contact still, but a fighter can definitely get much closer than a capital ship. Because a fighter individually isn't very helpful against a capital ship, and a fighter cloud will still be highly visible, the fighter will need a dedicated payload for a particular job, for instance deploying ECM, chaff, or carrying a detonator of some sort (okay, maybe we're really talking about a missile nine times out of ten...) Definitely blinding your opponent should be your first priority, so I imagine you would have fighters dedicated specifically for attacking sensor systems. Capital ships can't conceal that they're accelerating, but they may be able to conceal the details of it. A pulsed fusion drive is just a series of fusion bombs. If I release a spread of fusion bombs around me, and they all go off in quick succession, I've now made a course correction but you can't (without observing me directly) tell which of those 'accelerations' were genuine and which were not. Similarly, a series of fighters carrying fusion bombs can paint me as having a much larger fleet than I really do. Regardless though, capital ships are going to ultimately find themselves charging directly at a target that knows it's coming. Blinding your enemy may buy you time or force him to misallocate resources, but you're never going to get close enough to fire on him without him seeing you and being able to fire back. So capital ships will need to be made to 'run the gauntlet', specifically at a large target likely with a defensive net. The most sensible thing then would for capital ships to have a very small cross-section, probably like a tube or triangular shape, since those naturally increase the structural integrity. In a nutshell, we should expect these to look like those beautiful old diesel subs (except giant - and with rail guns), and built primarily for a frontal assault. The front would be heavily armored, and this tactic is perfect for spinal weapons. The sides would have more focus on fighter/missile launching and point defense. There would likely be some weapons pointing out the aft so you can hit targets both ways when doing a fly-by, or to attack pursuers, but the focus is definitely on the front. Not sure where you'd put radiators, since that's a HUGE vulnerable spot. Fighter clouds would help to circumvent defenses, such as armored fores, weapons platforms, nano-disassembler clouds, etc. When two capital ships are fighting each other, the most basic tactic would be charging each other like a joust, trying to do the reverse of the old 'cross the T' (I guess 'line the T') and hit the vulnerable sides of the ship. Meanwhile, fighters and missiles are spreading out and attacking around the flanks, or fighting each other. Overall though I don't see capital ship jousting as being very common. If the other guy has a bigger force, it'll be obvious, and you stay out of range. Capital ships would instead be for attacking targets that can't move (like habitats), defending critical assets in transit (like troop carriers or shipments of antimatter), or defending stationary targets until they build better defenses.
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Wed, 2010-08-18 17:11
root root's picture
Re: Space naval combat (Segway from Antimatter thread)
root@Space naval combat If I have a correct summary of the difficulties: 1) Both sides have all relevant information available. 2) Both sides are able to perceive the information with needed accuracy. 3) Both sides are able to perfectly perform all the calculations necessary. 4) Both sides are perfectly rational. What we have here is not particularly different from Tic-Tac-Toe, in that there is always a correct, optimal choice to be made, and therefore the outcome is known before any moves need to be made. In order for space warfare to work, something needs to change with these conditions. Assuming you can't drive the other decision makers mad before engagement, and you are unable to sabotage their tactical computers, this leaves conditions 1 and 2. We need to deprive the players of perfect perception of relevant information. The difficulty of depriving the other side of information comes directly from thermodynamics, in so much as the cosmic background radiation is so bloody low temperature (2.7 Kelvin), that a lazy sneeze is packed with so much energy that it can be seen for thousands of kilometers (I didn't do the math on that, it's a rhetorical example). Before I go off on my theoretical strategies, does anyone know why a combatant entity can't produce clouds of ice and clouds of thermally radiant materials to mask their vectors?
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Wed, 2010-08-18 20:05
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
root wrote:
root@Space naval combat If I have a correct summary of the difficulties: 1) Both sides have all relevant information available. 2) Both sides are able to perceive the information with needed accuracy. 3) Both sides are able to perfectly perform all the calculations necessary. 4) Both sides are perfectly rational.
Well, 1 is not entirely true. You can infer a lot from some emissions, but you cannot reliably tell whether that little 10 cm 40 K glob is a hidden micromissile with antimatter warhead, just a sensor, a decoy or something else. Both sides can see what is moving, but there might be far too much stuff to get a complete picture (consider a fight around Earth). So there are going to be surprises, even if things turn out to be obvious in retrospect. 2 is also problematic. My calculations seem to show that even with distributed sensors communicating FTL, there are going to be uncertainty in position for things accelerating wildly. 4 is of course never true. They are not TITANs after all :-)
root wrote:
What we have here is not particularly different from Tic-Tac-Toe, in that there is always a correct, optimal choice to be made, and therefore the outcome is known before any moves need to be made.
No. The winning conditions are undefined - what constitutes a successful objective can be much more complex than just blowing up the enemy ship, and both sides might have non-zero-sum goals. Besides, many simple games are computationally impossible to solve despite their determinism. Space warfare is complex enough that it is not a chess game. Ships and missiles take evasive action based on quantum random number generators, making hits probabilistic. Hidden nanodrones and overlooked packages affect the battle. Uncertainty about stealth and illusion coatings confuse things (you might be detectable, but why give the enemy obvious information?) Survival of ships may depend on armour and engineering details.
Quote:
Before I go off on my theoretical strategies, does anyone know why a combatant entity can't produce clouds of ice and clouds of thermally radiant materials to mask their vectors?
See the analysis at Atomic Rocket. You need to get clouds that move to mask the Doppler effect.
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Wed, 2010-08-18 22:26
King Shere King Shere's picture
Re: Space naval combat (Segway from Antimatter thread)
Clouds, eh? What about intentionally polluting parts of space with clouds to ease stealth & reduce visibility? Another similar tactic could be exploiting drifting micro-hazard fields & destroyed ship remnants from prior conflicts. Ship graveyards becoming instruments of shiphazards.
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Wed, 2010-08-18 23:04
OneTrikPony OneTrikPony's picture
Re: Space naval combat (Segway from Antimatter thread)
Couple a thoughts; On Weapons: The most powerful weapon on a ship is might be it's own engine. I cant claim to comprehend how an anti mater drive works but IIRC the exhaust velocity of a fusion drive ship is something like 17 billion or 1.7 billion Km/sec. Which seems like it might extend a really powerful torch for a really long distance. (I remember reading that on the atomic rocket site years ago.) On Deep Space warfare: It seems unlikely that in a setting with EP level tech you'll ever have armed conflict way out between one destination and another. With the stated Delta V capacities of EP ships and the distances involved a chance interception is exceeeeedingly unlikely. And it doesn't make sense to purposely send ships to intercept other ships when you know they're coming and you can just sit back and wait while you load up extra missiles instead of fuel. (Joel haldeman had some things to say about this, and I always wondered how "Forever War" and "Forever Peace" aren't listed as inspirational to EP.) So, Probably all armed conflict is going to happen near to the home of one side involved. The home team has a massive advantage in not having to burn tons of payload to get to the party. They have another massive advantage in (presumably) being able to Refuel. And as has been noted, Point Defense Lasers run by AI are extremely effective. The Away team is in bad shape from the start. They have to decide how much offensive mass to load and how much reaction mass to load and still leave enough deltaV for combat maneuvers. As has been noted Point defense lasers are effective so they shouldn't even bother to attack unless they can afford to freight enough offensive mass to overwhelm the defenses of the Home team. Unless the away team is just going to do a fly-by, (and what would be the point of that?), they have to expose themselves by making a burn to accelerate down to and orbit of the target. So No mater how cold and quiet they keep their ship while it's coasting they're going to get noticed as they approach. Not only that but they have to win the objective before they've burned too much fuel to return home or they have to abandon ship and Farcast back. Finally: Why, given the massive expense of launching an armada capable of overwhelming the defender with any decent probability of success, would you bother to attack people worlds away who are probably not an immanent threat? Obviously it happens, the PC has attacked Locus twice from Mars. But you still gotta wonder; Why? That would be like if the US attacked some country just because some of their people were... Fuck-it, never mind. Why is irrelevant.
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Wed, 2010-08-18 23:28
icekatze icekatze's picture
Re: Space naval combat (Segway from Antimatter thread)
hi hi Clouds, debris fields and un-powered fighters run afoul of the "space is really big, like, super big," problem. Even if you had a cloud that could hide your ship, without dispersing too much and somehow being able to absorb all that thermal radiation (don't ask me how, I wouldn't know) your enemy will still know what your position is because they have calculated your vector based on your last maneuvering burn. Should you decide to maneuver again, you are going to leave your cloud/un-powered fighter behind. Exhaust from a fusion or anti-matter rocket ship is definitely going to be very dangerous at close range, but since it is unlikely to be very collimated you'll need to be practically right on top of your enemy to use it. Also, the speed of light is just under 300,000 km/s, so that is really the upper limit on exhaust velocity, not 1.7 billion km/s. I can think of some very good reasons to intercept someone in deep space. I will relate a particularly poignant one. A cargo vessel is carrying a highly important piece of technology to a research facility on one of Saturn's moons. It was supposed to be traveling low profile, but someone leaked the information to the Jovians. The Jovians scramble a fleet to intercept it, with orders to capture if possible or destroy the vessel if capture is impossible. The cargo vessel pushes it's engines as hard as it can, but it is no use, they know they will be intercepted before they reach Saturn, so an escort fleet is dispatched to intercept the Jovians. A dangerous game of brinksmanship ensues, but when it becomes clear that diplomacy will not stop the attack, there is a pitched battle. In the end, both fleets are decimated and the cargo vessel escapes with it's precious cargo. The defenders don't have quite so huge of an advantage being able to mass at a gravity well. Gravity wells are notoriously good targets for bombardment. A defense fleet is going to want to intercept the aggressors before they can get too close.
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Thu, 2010-08-19 00:31
OneTrikPony OneTrikPony's picture
Re: Space naval combat (Segway from Antimatter thread)
Sorry about my unintended hyperbole. I bothered to look it up this time. And it should have been million instead of billion. Also it should have been m/sec. not Km/sec. And actually it should have been 7.8 millin m/sec. if EP ships are using He3-D fusion. For some reason I was under the impression that the exhaust was fairly columnated. Seems like I read something about it being a beam of Ions 20 km long or something like that. I don't do math or science, I'm just a groupie. :D "A cargo vessel is carrying a highly important piece of technology [From Where?] to a research facility on one of Saturn's moons." Probably it's not comming from the inner system unless it's stolen tech. It could be comming from the main belt. In either case the Titanians don't have a prayer of catching the Jovan fleet before the Jovans can get to your ship. It's probably comming from some other Autonomist outpost in the outer system, in which case the Jovans know absolutely that it's going to an orbit around Saturn and are most likely to catch it there. That would be a desparate move because they're picking a fight in the Titanian's back yard. But the target ship knows as soon as the Jovan Fleet launches and can easily drop mass and redirect to another port or just return home. Regardless, it's not traveling on a ship unless you can name 3 "highly important pieces of technology" that cant be digitized and have to be physicaly transported in the EP setting. No one keeps thier defensive Materiel down a gravity well. If the interdiction of earth can be set up in a period of months so can any moon or habitat be similarly guarded and much more quickly. Defence of a fixed point is only a dissadvantage if your on-sight resources are limited to less than twice that of the attackers. Meaning that attackers are at a supply disavantage to all but small habitats. If you're only attacking a small habitat you wouldn't expect them to be able to mount a defence at a significant distance; say more than 1.5 million KM. Incedently; while the Atomic Rockets page is pretty adamant in their position that "space fighters are stupid." I think they overlook two points. One, that fighters are necessary if your objective is other than to destoy. In those situations the navy's job is done and it's time to bring in the Marines--think Landing craft. Two, obviously the writer and contributiors of Atomic Rockets aren't dealing with the Eclipse Phase concept of Digitized Minds. At the point where a fighter is driven by a digital pilot the only diference between a fighter and a misile is it's DeltaV capacity. There's a reason that fighters kinda make sense in StarWars but less so in Startrek
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Thu, 2010-08-19 02:22
root root's picture
Re: Space naval combat (Segway from Antimatter thread)
OneTrikPony wrote:
Regardless, it's not traveling on a ship unless you can name 3 "highly important pieces of technology" that cant be digitized and have to be physicaly transported in the EP setting.
1) 1 time cipher pad 2) qbits 3) Any sample of Exsurgent corruption
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Thu, 2010-08-19 06:48
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
I have been thinking about the limits of lasers. If you want to hurt somebody, you want to focus as much energy on them as possible. While lasers in everyday life look like perfectly collimated lines they do disperse slowly: over typical space distances this can be more than enough to render them useless. For a Gaussian beam (the simplest model) you get a hyperbolic divergence. If your gun is at the waist and has radius r, then the width of the beam at distance d will be r*sqrt(1+[lambda d/pi r^2]^2) where lambda is the wavelength. The energy per square meter will be I/[pi (r^2 + lambda^2 d^2/pi^2 r^2)] - it will decline with the square of the distance and wavelength used. Short wavelengths are nice. Let's assume a 500 nm visible light laser, a big ship laser 10 meters across (I imagine a big phased array construction). Then at 1000 km away the beam is still nearly 10 meters across. In fact, you need to go a million km away before it doubles in size. Sounds good, right? But this just means the intensity will be close to what it was near the firing ship. Ideally you want to deposit so much energy on your enemy that he breaks but not risk the same in your gun - you want to focus a large source with a manageable energy density onto your pesky enemy. If we turn the beam equation around and try to aim a converging beam onto a narrow (and hot) waist, we get an equation I am too lazy to solve this morning. But there is a simpler approximation for long distances, saying that the divergence angle of the beam is lambda/pi r (where r is the waist size). So if I am at distance d and has a radius R laser, r = d lambda/pi R. For the above example r=1.5 cm, an almost 444,000-fold increase in intensity. If my laser was a bigger phase array with R=100 m, I could get a focal point 0.1 mm across - that would likely hurt a lot. While the waist of the beam is narrow it is also pretty long: for the first case the focal depth is 2.8 km, and in the second 12 meters. You need to ensure your enemy is where you point the beam, otherwise you will just illuminate him. Now, this suggests another reason you don't want to fight close to planets: stationary defence stations can easily set up pretty big phase array lasers, and then they can blast you very well. Ships could in principle unfold big arrays too, but I expect it is hard to both power them and keep them accurately pointed while dodging incoming lasers, projectiles and missiles. This kind of laser arrays still have the problem that if you are uncertain of exactly where the enemy is (and we are talking about meters here) you will miss him. So my previous calculations still apply - the Titan moon lasers can vaporize nearly anything, but if you are more than a few thousand kilometres from a sensor that pinpoints you and flying evasively, they will not be able to hit you.
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Thu, 2010-08-19 07:08
icekatze icekatze's picture
Re: Space naval combat (Segway from Antimatter thread)
hi hi The thing is that in space, 20 kilometers is essentially point blank range. Weapons are going to have ranges of thousands of kilometers, if not hundreds of thousands. The Titanians may not have a prayer of catching a Jovian fleet if the cargo ship is traveling to Saturn via Jupiter, but Jupiter could be on the opposite side of the Sun at the time, or any other position inbetween. In reality, the planets usually don't line up neatly like they do on distance charts. Plus there are likely military outposts at various lagrange points or other orbital vectors for the big players. If it is a cargo of stolen tech, there's a good chance they can't turn around and go "home," or go to a different port for fear of confiscation. I am a little confused, you say that no one keeps their defensive material in a gravity well, but that the defenders will have more defensive material. Why is this? If people keep their equipment outside of the gravity well, what is to stop the attackers from assembling a larger force? Infomorphs really blur the line between missile and fighter to the point where I'm not really sure it is a useful distinction to make, given the usage. The thing that makes fighters/missiles viable in Eclipse Phase is the relative weakness of point defense. ----- You could definitely make some very powerful, very long range laser weapons out of a static structure. Think of a phased array the size of a deep space radio telescope! However, such installations do become prime targets for mass driver bombardment since their maneuvering capability will be limited, but I am still of the opinion that most space combat is not going to take place near a planet. I don't recall reading anything about any one group invading another through military force, so my guess is that they'd be messing with each other's affairs out in the open where they are relatively safe from reprisal.
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Thu, 2010-08-19 09:57
OneTrikPony OneTrikPony's picture
Re: Space naval combat (Segway from Antimatter thread)
the PC attacked Locus, Twice. search the core book for "Locus" I'm under the impression that at EP tech levels the gravity well from orbit of any of the occupied planets and moons, including Venus, is negligible to the fuel costs of moving things around the system. Space navy supplies are already in orbit. In many cases the gravity well isn't an issue because the defensive position is a micro-gravity habitat like Locus, or Eris, Fresh Kills, the Hexagon. Even still, it seems a lot easier to fab some chemical rockets to push more payloads up to resupply your depots then it is to freight the equivalent from Jupiter to wherever the Jovans might attack. I think the Defensive perimeter of most habitats is going to be somewhere around the 1.5 million Km that fusion ships can cover in a day. I think the Defense sets the range of most engagements. And I think it's to their benefit to be closer to home.
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Thu, 2010-08-19 11:35
Byzantine Laser Byzantine Laser's picture
Re: Space naval combat (Segway from Antimatter thread)
With dumb AI trivially easy to make, it seems like one cheap tactic would be to mass-produce smart mines/missiles. Don't bother putting any explosives in them or anything, just make them a chunk of mass with basic thrusters that are just smart enough to plot a trajectory. Maybe coat it in a good near-blackbody material if you want to get fancy. Have them sit in orbit until you detect an unwelcome visitor. Once they see somebody inbound, have hundreds of them accelerate on an intercept course--not particularly quickly, just fast enough to hit the target. At the speeds the ships are likely traveling, it'd be about like dropping a cinder block onto a car going at 65 mph if one hits. Even if they shoot them down, they'd just be facing dozens of clouds of debris heading their way, which is still quite dangerous at those speeds. A few downsides I can see to this approach: -Short-ranged: If the enemy can bombard you with a railgun from 1000 km away, this won't help you much. -Dangerous: Having all that junk floating around is as much a danger to your own traffic as it is to any enemies, unless you manage to keep travel paths clear.
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Thu, 2010-08-19 11:44
Extrasolar Angel Extrasolar Angel's picture
Re: Space naval combat (Segway from Antimatter thread)
How about simple Sandcasters as defense against low-armoured fighters?
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Thu, 2010-08-19 12:12
nezumi.hebereke nezumi.hebereke's picture
Re: Space naval combat (Segway from Antimatter thread)
Pony - you actually answered some of your own questions. Imagine this simple setup - the Martian Cycler, Transcendant Blossom is travelling between Mars and Earth. They are largely unpowered, and rely instead on the gravity paths of the two planets. On board the Blossom is the Argonaut memeticist and cultural leader, Larns Thein. Thein is a valuable person and has access to a unique set of skills. The Triads decide they wish to capture Thein. They recognize that attacking the Blossom while in orbit around Mars or Earth will result in it being defended by the heavy platforms and Direct Action ships in the neighborhood. So instead, they map out the course (easily available and difficult to change) and send out a set of small warships to attack it while it's en route, with the goal of disabling the ship, extracting Thein, and holding his ego either as ransom or as a slave (plus auctioning off all the other egos on board as ransom and keeping the ship itself as a new barge). Now you have space combat :) To make things more interesting, Direct Action receives word of the attack while the Blossom is .2 AU away, so they light up their engines and head out. The Blossom is too slow to adjust its course and avoid attack, so instead DA must defend it from boarding. Once the Triads get on board, it'll be much easier for them to capture prisoners, steal their heads and harvest their egos for ransom - best to stop them in space, while damage is minimal. So they send out a few small cruisers of their own as escorts. As the Triad ships approach, they realize they're in trouble. They didn't anticipate serious protection. Their ships only have enough fuel for taking the trip one way, after which the crew would egocast off and leave the ships following the same gravitational path as the Blossom itself, for later recovery. Now the Triads can either turn tail and run - abandoning all of their requipment for DA capture and failing the mission - or fight difficult odds on the possibility of success and profit. Now you have rational, armed combatants fighting a superior force. There are very many things which will be transported through space. Antimatter, H3, carbon, water, new ships, military squads, pleasure barges, TITAN artifacts, Exoplanet finds, scum crews, research vessels.... Most of these don't have the luxury of tons of fuel to burn on excessive maneuvering. Many will be fired off to follow the Interplanetary Transport Network. That means they will generally follow relatively few, well documented routes, modified based on destination and time. If a target can be spotted early enough (or found through other intelligence), its future coordiantes can be predicted - and there may not be much anyone can do to change that, even if it's known there's an ambush ahead. I imagine a large percentage of ships in the system are 'ghost ships' - ships left basically without a crew, guided on by an AI and physics, oftentimes carrying valuable cargo and expecting a network on Earth to provide proper tracking and defense when necessary (or at least not expecting a tenfold increase in population in space). A large percentage of the crewed ships will also rely on ITN. Almost all ships will rely on getting from habitat A to habitat B, which are both known points. All of these make attacks possible (even if difficult), with it growing more likely as you get closer to major waypoints like gravity wells.
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Thu, 2010-08-19 13:43
Byzantine Laser Byzantine Laser's picture
Re: Space naval combat (Segway from Antimatter thread)
This all got me thinking more on the topic of cheap and dirty warfare. On this note, another I was thinking of was just how easy it is to deny orbits. A few tons of scrap rock or metal scattered in orbit around a planet could deny most conventional traffic to and from it for months. (As an aside, I recall reading an article about how something similar could have been considered as a scorched earth tactic during the space race.) On a larger scale, strap a cheap engine to a small asteroid to put it on a collision course with a planet or space station, and even blowing it up will likely not be much help unless you vaporize it. And then there are nanobots... there are so many ways to fight dirty with those that I can barely even begin to think of them. Grey goo, nanoscale delivery systems for everything from rare viruses to immune suppressants, espionage, demolitions--if they can be used to hollow out an asteroid to make a habitat, I don't see why they'd have huge problems doing so beneath an enemy factory. Altogether, between this stuff and the likely high costs of space combat, I assume that cold wars are the name of the game. Outright warfare would likely be short, very deadly, and leave less for everybody. Not too dissimilar to nuclear war, actually. The only winning move is not to play. (And it makes me want to introduce some radical terrorists as enemies in my game.)
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Thu, 2010-08-19 16:42
root root's picture
Re: Space naval combat (Segway from Antimatter thread)
The nanobots are a very good idea. If you send a dust of them on a collision vector with a ship, it might go unnoticed. I'm thinking a great method of espionage would be to convert patches of hull to transceivers. Signal warfare problems pop up as usual, but it's a start.
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Thu, 2010-08-19 17:24
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
root wrote:
The nanobots are a very good idea. If you send a dust of them on a collision vector with a ship, it might go unnoticed. I'm thinking a great method of espionage would be to convert patches of hull to transceivers. Signal warfare problems pop up as usual, but it's a start.
Some fragility issues, but I think one can design nanobots to survive a 10 km/s impact - it is enough that a few survive. Once you have a transceiver on the enemy you have a much easier time targeting him, since you could figure out his position and accelerations exactly. It is still not perfect - the patch has to signal back to one of your sensors, but it will really help approaching missiles to aim. However, space is still absurdly big. You cannot just spread a cloud of nanites and hope they will hit, you need to get pretty close to have any chance of getting a few onboard.
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Thu, 2010-08-19 20:56
jsnead jsnead's picture
Re: Space naval combat (Segway from Antimatter thread)
root wrote:
OneTrikPony wrote:
Regardless, it's not traveling on a ship unless you can name 3 "highly important pieces of technology" that cant be digitized and have to be physicaly transported in the EP setting.
1) 1 time cipher pad 2) qbits 3) Any sample of Exsurgent corruption
4) Antimatter 5) Alien artifacts (from the other side of a Pandora gate) 6) New elements and other exotic materials created in specialized facilities that are expensive to duplicate. 7) Genuine pre-Fall artifacts from Earth (not technology, but still very valuable).
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Fri, 2010-08-20 14:14
King Shere King Shere's picture
Re: Space naval combat (Segway from Antimatter thread)
I imagine missiles and mines as a delivery systems for nano & micromachines. One type detach a second wave of "clean up" before it impacts, another type breach into the target & release its boarding-party. These delivery systems could also be smarter a adapt to situations & target; capable of using these & different strategies to maximise (or minimize) doom.
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Fri, 2010-08-20 15:01
icekatze icekatze's picture
Re: Space naval combat (Segway from Antimatter thread)
hi hi Destroyers in Eclipse Phase seem to have a role similar to what cruisers would have in contemporary terms. Mainly, they are capable of long range independent operations, and engage in a wide range of missions. I think a battleship would be dedicated to destroying other capital ships, and thus would be designed very differently from a Destroyer. I think a battleship might actually be a two stage vessel. One stage holds a high efficiency anti-matter drive, crew compartments, repair facilities etc. However, the second stage is all fight. It would have a high thrust rocket with handling and acceleration comparable to a fighter, bristling with weapons and no living amenities. Logistics concerns would mean that Battleships are only brought out for big fights, but a typical engagement would likely involve the entire assembly moving near the engagement zone, but at about the same time the Destroyers are launching fighters, the Battleship separates it's second stage which then goes on ahead while the first stage retreats or falls in with the destroyers.
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Fri, 2010-08-20 18:54
nezumi.hebereke nezumi.hebereke's picture
Re: Space naval combat (Segway from Antimatter thread)
The problem with deploying nanomachines is firstly, getting them out there, which requires a delivery system (which then implies that anyone who has been watching the area will know that the place has been trapped, or again you have rockets you can fire at before they reach the target), and secondly, that when you have a high enough concentration of nanobots to quickly turn the tide of battle, I imagine that would come up on things like radar. On the flip side, you can make a rocket with a warhead full of nanomachines. If the rocket is destroyed before reaching the target, the nanomachines will continue on that course, spreading out slightly, making a nice shotgun spread. If they're close enough to the target, and the target doesn't change course, it could still be an effective attack, and the only real defense is some sort of magnetized or ionized hull, and counter-nanobots (or just being honking massive). I like the idea of a two-stage spaceship. That's definitely thinking out of the box, and it would make sense. By leaving behind the low delta-v engine, the extra fuel tanks, etc., you reduce your mass and increase your maneuverability in a way that otherwise would be impossible. The non-combat part can also be used for duties like sensors, communications, triangulating targets, launching long-range weapons, etc.
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Fri, 2010-08-20 19:15
King Shere King Shere's picture
Re: Space naval combat (Segway from Antimatter thread)
Suddenly I think of Star Wars "Death star". A Bit to big & mobile to be a "mere" spacestation & its no moon. In harder Sci Fi, It would not be good thing for a planet; to have a Death Star detonate near it. "kamikaze moons" Rather than constructing a "fragile" battleship craft, I imagine its sound to arm, outfit & accelerate robust celestial objects. These can serve the same function as battleships/spacestations/mobile forts & or as weapon platforms intended for a implacable attack. Something really bothersome for the opposition to destroy. Perhaps almost as bothersome as the effort to move & accelerate It; in a desired heading. . Even more evil is to attack with one of the opponents own objects. What conventions of war remains & who follows them? "Sir, something has set one of our larger space stations on a collision course with us" "One of our civilian space stations? Evasive actions!" "Sir, its correcting its heading & continues to accelerate" "Call up fleet command for instructions & request permission to use suppressive force against a hostile civilian target"
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Sat, 2010-08-21 15:41
babayaga babayaga's picture
Re: Space naval combat (Segway from Antimatter thread)
In terms of hiding your IR signature, it should not be too hard, though it will cost you some energy/mass. In a nutshell, you have to export your heat/entropy packaged into a tight beam towards a direction where it's not likely to encounter an enemy sensor. Unless the system is *really* packed with enemy sensors, it seems very likely that you can do so with extremely high probability. Keep in mind that you do not need to do so continuously, but just with occasional pulses - just before changing direction and/or using decoy mirrors (or your reaction packages, see below) to redirect the beam. You probably also want to maintain a "directional" heat signature - similar to what is done with active camouflage clothing - so that a craft that has you eclipsing the sun from their point of view does not see a cold, suspicious spot. Using heated hydrogen as reaction mass for "stealth" maneuvering is a really dumb tactic - since the plume *will* radiate a reasonably visible IR signature. But nothing forces you to do so. Just use the equivalent of a big railgun to send reaction mass, in occasional pulses, in the opposite direction you want to accelerate. Again, you are hoping nothing lies in the *exact* trajectory of the reaction mass (after all, space is very big and very empty). If it's smart matter than can camouflage itself (see above), serve as a sensor or mirror (see above), or just *eat* any enemy it comes in contact with, so much better. In terms of weapons, I think that the ultimate weapon are nanobots - smart matter. Anything else - projectiles, laser beams, perhaps even antimatter - should be cannibalizable by the nanobots of the defender. With nanotech, throwing dumb stuff at the opponent is generally *helping* them. I am not too sure how a smart matter vs. smart matter fight would end up - for symmetry principles, I'd guess that whoever has the largest mass wins, though technological differences could mean that a mass of superior nanobots could probably beat a slightly larger, but "slightly-less-smart" mass. In short, it's a little like traditional battles, with larger/better armies usually winning the day. It's just that the soldiers are very small.
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Sat, 2010-08-21 16:37
icekatze icekatze's picture
Re: Space naval combat (Segway from Antimatter thread)
hi hi King Shere: While I don't argue that an asteroid might make a useful weapon if set up properly, I am curious as to where you propose to place the reaction mass. External tanks are going to be just as vulnerable to weapon fire as any other ship, and if you hollow it out to store reaction mass internally, doesn't it lose it's status as a robust object? If it is big, it is going to need big engines otherwise it'll be very slow and an easy target for defensive fire, or the defense could just launch their own asteroid to smash into it in the opposite direction. I think, in order to use someone's own space station against them as a weapon, they'd need to kill off everyone on board first. Anyone still alive onboard could fix any errors in course manually. Their maneuvering thrusters can't work if they're physically disconnected from their propellant source. ----- babayaga: You could make a heat laser, but the act of collimating the energy it would necessarily produce more heat than it disperses. Without collimating the waste heat, it will disperse using the inverse square law and thus greatly increase the area in which an observer can be situated. Also, it doesn't matter what kind of material you are using as reaction mass, if you are accelerating it, it is going to pick up heat energy and produce a clear signature. A trail of hot magnetic slugs is going to be just as visible as hydrogen. The only way to cool off a reaction mass is to slow it way way down, and in that case your ship isn't going to travel very far. (it is perhaps a common misconception that friction is the only source of heat in a railgun.) Nanobots are pretty awesome, but they're not that awesome (unless they're TITANs, in which case anything nano or otherwise is that awesome) Projectiles, through virtue of Newton's Third Law of Motion, will necessarily transfer their kinetic energy into whatever they hit (and vise versa) so without regard for the material's size or composition, at stellar velocities they will flash vaporize on impact. Especially given the fact that nanobots are, by their small nature, not very resilient to heat. They probably wouldn't survive an impact of more than a few kilometers per second. That is not to say a soft landing by a projectile would be impossible, or that it wouldn't have any tactical value, but I would think it might be more in the lines of covert operations than as a weapon of destruction. Especially considering that the opponent could have counter nano-bots or even just excise the infected portion of the ship and jettison it. However, a few well placed nanobots that get into the opponent's computers could have devastating effects if they go un-noticed.
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Sat, 2010-08-21 16:51
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
babayaga wrote:
In terms of hiding your IR signature, it should not be too hard, though it will cost you some energy/mass. In a nutshell, you have to export your heat/entropy packaged into a tight beam towards a direction where it's not likely to encounter an enemy sensor.
To quote from http://www.projectrho.com/rocket/rocket3w.html (which is almost frightening in how well it covers this thread):
Quote:
"Besides, redirecting the emissions merely relocates the problem. The energy's got to go somewhere, and for a fairly modest investment in picket ships or sensor drones, the enemy can pretty much block you from safely radiating to any significant portion of the sky. And if you try to focus the emissions into some very narrow cone you know to be safe, you run into the problem that the radiator area for a given power is inversely proportional to the fraction of the sky illuminated. With proportionate increase in both the heat leakage through the back surfaces, and the signature to active or semi-active (reflected sunlight) sensors. Plus, there's the problem of how you know what a safe direction to radiate is in the first place. You seem to be simultaneously arguing for stealthy spaceships and complete knowledge of the position of enemy sensor platforms. If stealth works, you can't expect to know where the enemy has all of his sensors, so you can't know what is a safe direction to radiate. Which means you can't expect to achieve practical stealth using that mechanism in the first place. Sixty degrees has been suggested here as a reasonably "narrow" cone to hide one's emissions in. As a sixty-degree cone is roughly one-tenth of a full sphere, a couple dozen pickets or drones are enough to cover the full sky so that there is no safe direction to radiate even if you know where they all are. The possiblility of hidden sensor platforms, and especially hidden, moving sensor platforms, is just icing on the cake. Note, in particular, that a moving sensor platform doesn't have to be within your emission cone at any specific time to detect you, it just has to pass through that cone at some time during the course of the pre-battle maneuvering. Which rather substantially increases the probability of detection even for very narrow emission cones. "
Basically, the problem is that you try to turn a omnidirectional, always on heat source into something that is unidirectional and occasionally on, but has the same average power. Manipulating high power energy tends to incur thermodynamical losses proportional to the power, so now there is a real problem with getting heat emissions from your decoy mirrors and slowly cooling emitters. Perfect stealth might not be necessary if you are confusing enough, but it is not going to provide reliable security.
Quote:
Using heated hydrogen as reaction mass for "stealth" maneuvering is a really dumb tactic - since the plume *will* radiate a reasonably visible IR signature. But nothing forces you to do so. Just use the equivalent of a big railgun to send reaction mass, in occasional pulses, in the opposite direction you want to accelerate.
You could use *cold* gas for stealth manoeuvring. Just release some sufficiently cool argon under pressure. Railguns will produce electromagnetic signals with a characteristic directionality, so they might reveal your position and direction.
Quote:
In terms of weapons, I think that the ultimate weapon are nanobots - smart matter. Anything else - projectiles, laser beams, perhaps even antimatter - should be cannibalizable by the nanobots of the defender.
How do you think nanobots could cannibalize antimatter? One touch of a matter tooltip to an antimatter atom, and now you have some hard gamma instead. Similarly high intensity laser radiation can be pretty good in ionizing nanobots - and in nanostructures ions and free radicals are terribly destructive. Smart matter is limited by thermodynamics, available information, time, energy etc. It is not magic. When a rail-gun projectile arrives at 50 km/s, there is not enough time to do anything with it until after it has deposited its explosive energy throughout the impact path, destroying whatever infrastructure was there. And the attacker might be cheap enough to just send some low-energy, high-density matter like lead that cannot be used for much but impact mass.
Quote:
I am not too sure how a smart matter vs. smart matter fight would end up - for symmetry principles, I'd guess that whoever has the largest mass wins, though technological differences could mean that a mass of superior nanobots could probably beat a slightly larger, but "slightly-less-smart" mass. In short, it's a little like traditional battles, with larger/better armies usually winning the day. It's just that the soldiers are very small.
I have actually been tinkering with this for a paper. If you start with the Lanchester equations you get some interesting possibilities. If the square law applies, then the factor that matters is the square of the number times the quality. That would make mass the really deciding factor, helping defenders against nanoattackers. But when you consider the derivation it looks more like the linear law, in which case the deciding factor is just number times quality. So there might be better chances for a really efficient attacker. But these equations need to be changed if you take reinforcements, especially self-replicating reinforcements, into account. My conclusion so far has been... ahem... that I have no conclusion yet. It is complicated.
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Sat, 2010-08-21 18:47
babayaga babayaga's picture
Re: Space naval combat (Segway from Antimatter thread)
icekatze: I fail to see why a heat laser could not remove more entropy than it produces (see e.g. http://adsabs.harvard.edu/abs/2008PhRvA..77f1401M) Also, I fail to see why "it doesn't matter what kind of material you are using as reaction mass, if you are accelerating it, it is going to pick up heat energy and produce a clear signature." There is no fundamental reason why you can't accelerate some mass while adding to it an arbitrarily small amount of entropy. Finally, I fail to see why a smart material would not be able, in principle, not only to avoid being "vaporized", but also to actually cannibalize energy from the projectile. All you need to do when facing a "dumb" slug is to: 1) analyze in real time it shape and speed - a small cloud of smart dust orbiting a few dozen meters around the ship can easily do so when being hit by the projectile, and trasmit the information to the core of the ship before the projectile is halfway through those meters. 2) reconfigure the smart material out of which the ship is made *locally* (i.e. no atom get moved by more than a few atomic radii) in such a way that it will part almost without friction as the projectile hits it, and close behind it, except for a small portion of matter that gets carried away by the projectile. 3) this portion of matter simply spins itself into a several (thousands?) kilometers long, elastic filament that captures the mass and energy of the projectile over a few seconds to a few minutes.
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Sat, 2010-08-21 20:55
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
babayaga wrote:
I fail to see why a heat laser could not remove more entropy than it produces (see e.g. http://adsabs.harvard.edu/abs/2008PhRvA..77f1401M)
Nice paper, but it is about how much entropy a cooling laser can remove from atoms it shines on, not from the laser generating system. The efficiency of the cooling is anyway rather low, about 20%.
Quote:
Also, I fail to see why "it doesn't matter what kind of material you are using as reaction mass, if you are accelerating it, it is going to pick up heat energy and produce a clear signature." There is no fundamental reason why you can't accelerate some mass while adding to it an arbitrarily small amount of entropy.
You are doing work on the material, increasing its kinetic energy. There will be a thermodynamic loss turning some of the work into waste heat. It seems pretty implausible that this will distribute itself solely on the railgun and not the projectile.
Quote:
Finally, I fail to see why a smart material would not be able, in principle, not only to avoid being "vaporized", but also to actually cannibalize energy from the projectile. All you need to do when facing a "dumb" slug is to: 1) analyze in real time it shape and speed - a small cloud of smart dust orbiting a few dozen meters around the ship can easily do so when being hit by the projectile, and trasmit the information to the core of the ship before the projectile is halfway through those meters. 2) reconfigure the smart material out of which the ship is made *locally* (i.e. no atom get moved by more than a few atomic radii) in such a way that it will part almost without friction as the projectile hits it, and close behind it, except for a small portion of matter that gets carried away by the projectile.
2 is the problem. The matter hit by the projectile cannot get out of the way in time, although it could probably break the strong mechanical links to the rest of the ship that would transmit momentum and force. So the projectile will slam into this part of the matter, imparting momentum to it at a very high rate. This will produce heat, and for a typical railgun projectile you get temperatures enough to disrupt nanomachines (see previous estimates of railgun energies). Even if the smart matter organises itself as smartly as possible the matter of the projectile will be compressed in an entropic fashion and heat up as it pancakes. The best you could do is likely a ship that removes its armour and bulkheads where it is hit, allowing projectiles to barge straight through with as little damage as possible. If you can avoid having all the energy released inside your ship and can repair the holes, then it is probably worth it.
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Sat, 2010-08-21 23:39
King Shere King Shere's picture
Re: Space naval combat (Segway from Antimatter thread)
icekatze wrote:
While I don't argue that an asteroid might make a useful weapon if set up properly, I am curious as to where you propose to place the reaction mass. External tanks are going to be just as vulnerable to weapon fire as any other ship, and if you hollow it out to store reaction mass internally, doesn't it lose it's status as a robust object?
The robust asteroid could perhaps have "tubes" drilled into it where the rockets & or the payload delivery system is. I think it depends on the choice of propulsion, how much the gloves are off & what's available. [i]VASIMR or VASIM rockets[/i], looks promising for meteor mitigation, or for our "curling stone" http://en.wikipedia.org/wiki/VASIMR If the gloves are off & my "Evil" hat is on; [i]Nuclear pulse propulsion[/i] http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion http://en.wikipedia.org/wiki/Antimatter_catalyzed_nuclear_pulse_propulsion The idea is to launch/drop small shaped charge fission or explosives out the rear, detonating them at a short distance, and use the generated blast to achieve propulsion. The rear is re-enforced to achieve a efficient push- Aside from outfitting a "curling stone" with propulsion of its own or a hijacking, I also imagine scenarios where the "curling stone" is towed or pushed with specialised tug ships (or regualar ships) to do the deed. Perhaps a whole fleet of military ships ganging up on a unsuspecting orbital station, accelerating it in a desired/unhealthy direction instead of simply blowing it up.
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Sun, 2010-08-22 14:34
icekatze icekatze's picture
Re: Space naval combat (Segway from Antimatter thread)
hi hi babayaga: As Arenamontanus has already pointed out, a cooling laser is not quite what you think it is. They generally only work on very small numbers of atoms, because atomic interactions can disturb the process; atoms that are already very cold, because the frequency of the laser is dependant on the resonant frequency of the atom in question; and they require the atom to be held within an electromagnetic trap of some sort. (typically a Magneto-optical trap, Penning Trap or a Paul Trap) Nanomachines are notorious for being slow, that is one of several of their limiting weaknesses. For nanomachines, building new structures happens more on the scale of growing a plant. Sure, it is like a very fast and highly advanced plant, it is still roughly on that scale, not thousands of meters per second. If that kind of technology were available, there would be no point to the weapon tables in the book because any projectiles or energy beams would just pass harmlessly through someone. However, in the core book they specifically say that "self-replicating nanoswarms with the ability to transform or destroy anything through the power of geometric growth remain out of transhumanity's grasp." ------ King Shere: There's no need to pull the gloves off as it were, the anti-matter drives that warships already use are just as, if not more potentially destructive as the nuclear pulse drives described. The issue is not the power of the drive, it is the mass ratio of the object. (the ratio of propellant to other mass) A nickel-iron asteroid would be a difficult nut to crack, but I don't see why regular warships would be unable to achieve the same structural integrity using advanced diamond composites and things. It is just a matter of how thick you want to make the hull. Perhaps there might even be a sort of hybrid, asteroid/warship creation where they reconfigure asteroids into warships kilogram for kilogram. I could see tugs flinging a plain asteroid towards a planet and having the approaching fleet use it as an Enders Game style barrier between their approach and an static defenses, because one problem with an object that big is that it becomes difficult to evade weapons fire and they could conserve maneuvering propellant on the approach. I think if someone actually tried, they could make a massive orbital habitat sized mass driver and bombard a nearby planet without ever leaving their own. A giant laser array based on a moon or something could push asteroids out of their orbits from a long ways away too. The way I figure it, if you have control of orbital space such that you can tug stations and astroids around with impunity, anyone in that gravity well is essentially at your mercy anyway.
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Sat, 2010-08-28 00:01
Dry Observer Dry Observer's picture
Re: Space naval combat (Segway from Antimatter thread)
For canon info on the Planetary Consortium attacks on Locus, see page 101 of the second edition of the Eclipse Phase Core Rulebook. It doesn't say much, but clearly an anarchist cluster habitat (population 2,000,000+) was able to repel an invasion fleet, and, with Titanian help, the much more serious fleet that followed.
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Sat, 2010-08-28 00:16
Dry Observer Dry Observer's picture
Re: Space naval combat (Segway from Antimatter thread)
I tend to assume that most conventional ships -- of all but the most colossal size -- being dispatched in a hurry from major space-based military stations will be accelerated by those launching them. That might involve designs like giant railguns, huge lasers targeting an attached mirror, or what have you. Fighters launched in a hurry, say, an unexpected attack, will also be accelerated, though they are more likely to be firing their engines as they move. This gives each vessel a lot of momentum that they don't have to pay for with their limited on board energy stores.
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Sat, 2010-08-28 15:24
Dry Observer Dry Observer's picture
Re: Space naval combat (Segway from Antimatter thread)
Arenamontanus wrote:
Quote:
In terms of weapons, I think that the ultimate weapon are nanobots - smart matter. Anything else - projectiles, laser beams, perhaps even antimatter - should be cannibalizable by the nanobots of the defender.
How do you think nanobots could cannibalize antimatter? One touch of a matter tooltip to an antimatter atom, and now you have some hard gamma instead. Similarly high intensity laser radiation can be pretty good in ionizing nanobots - and in nanostructures ions and free radicals are terribly destructive. Smart matter is limited by thermodynamics, available information, time, energy etc. It is not magic. When a rail-gun projectile arrives at 50 km/s, there is not enough time to do anything with it until after it has deposited its explosive energy throughout the impact path, destroying whatever infrastructure was there. And the attacker might be cheap enough to just send some low-energy, high-density matter like lead that cannot be used for much but impact mass.
Quote:
I am not too sure how a smart matter vs. smart matter fight would end up - for symmetry principles, I'd guess that whoever has the largest mass wins, though technological differences could mean that a mass of superior nanobots could probably beat a slightly larger, but "slightly-less-smart" mass. In short, it's a little like traditional battles, with larger/better armies usually winning the day. It's just that the soldiers are very small.
I have actually been tinkering with this for a paper. If you start with the Lanchester equations you get some interesting possibilities. If the square law applies, then the factor that matters is the square of the number times the quality. That would make mass the really deciding factor, helping defenders against nanoattackers. But when you consider the derivation it looks more like the linear law, in which case the deciding factor is just number times quality. So there might be better chances for a really efficient attacker. But these equations need to be changed if you take reinforcements, especially self-replicating reinforcements, into account. My conclusion so far has been... ahem... that I have no conclusion yet. It is complicated.
I don't want to get too much into this subject -- unlike the subject of handweapons to be used against raging Cthuloid hellbeasts, these ideas might actually be used by someone, especially if technological progress manages a steady degree of acceleration -- but I do think there's one particularly powerful reason why no major power in the Eclipse Phase universe has gone to war with any other major or minor power, and why, other than Locus, even the major habitats haven't been hit... in the wake of what happened, twice, at Locus. Uncertainty. In addition to all the other reasons -- the overriding threat of the TITANs, the advantages due defenders, and so forth -- the real problem is that while you can come up with a plausible attack strategy against a "conventional" EP-era military, it all depends on information about that other side's defenses which may be misinformed, disinformation, missing key data, utterly outdated or simply wishful thinking. You honestly don't know if they've made a quantum leap in their sensor arrays, have filled that one asteroid with a core of extremely well-contained antimatter, have infiltrated your chain of command with sleeper agents, have psi-augmented/seed AI/Exhuman assassins poised to strike at will (or even if you look at them funny) or any of a thousand other factors. Also, you don't know how other forces in Eclipse Phase will respond to your assault. Given that these forces don't just include other polities and humanity/transhumanity as a whole, but the Factors, the Exsurgents, the Titans, the Exhumans and the Prometheans, that's a lot of forces to contend with if they decide to move while the bulk of your military is off "teaching those Extropians a lesson" or what have you.
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Tue, 2010-08-31 08:54
valen valen's picture
Re: Space naval combat (Segway from Antimatter thread)
icekatze wrote:
----- You could definitely make some very powerful, very long range laser weapons out of a static structure. Think of a phased array the size of a deep space radio telescope! However, such installations do become prime targets for mass driver bombardment since their maneuvering capability will be limited, but I am still of the opinion that most space combat is not going to take place near a planet.
Seems to me that this is an ideal giant rock defense. When some terrorist yahoo decides to steer a asteroid at you, you just am your "Phased array the size of a deep space radio telescope", hence forth known as a Death Ray, at the asteroid. You should have at least months of lead time to vaporize parts of the rock and change its course. I see a death ray as a useful component of a habitat defense as opposed to a super-weapon.
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Tue, 2010-08-31 09:02
valen valen's picture
Re: Space naval combat (Segway from Antimatter thread)
Arenamontanus][quote=babayaga wrote:
2 is the problem. The matter hit by the projectile cannot get out of the way in time, although it could probably break the strong mechanical links to the rest of the ship that would transmit momentum and force. So the projectile will slam into this part of the matter, imparting momentum to it at a very high rate. This will produce heat, and for a typical railgun projectile you get temperatures enough to disrupt nanomachines (see previous estimates of railgun energies). Even if the smart matter organises itself as smartly as possible the matter of the projectile will be compressed in an entropic fashion and heat up as it pancakes. The best you could do is likely a ship that removes its armour and bulkheads where it is hit, allowing projectiles to barge straight through with as little damage as possible. If you can avoid having all the energy released inside your ship and can repair the holes, then it is probably worth it.
Also, if the armour is made of smart materials, then it stand to reason that the incoming round is made of smart materials and/or carries an explosive warhead.
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Tue, 2010-08-31 15:47
The Doctor The Doctor's picture
Re: Space naval combat (Segway from Antimatter thread)
Byzantine Laser wrote:
With dumb AI trivially easy to make, it seems like one cheap tactic would be to mass-produce smart mines/missiles. Don't bother putting any explosives in them or anything, just make them a chunk of mass with basic thrusters that are just smart enough to plot a trajectory. Maybe coat it in a good near-blackbody material if you want to get fancy. Have them sit in orbit until you detect an unwelcome visitor. Once they see somebody inbound, have hundreds of them accelerate on an intercept course--not particularly quickly, just fast enough to hit the target. At the speeds the ships are likely traveling, it'd be about like dropping a cinder block onto a car going at 65 mph if one hits. Even if they shoot them down, they'd just be facing dozens of clouds of debris heading their way, which is still quite dangerous at those speeds.
Why not load them up with smart corrosives and use compressed gas for reaction mass? All the mine would have to do is land on the ship's hull seal itself in place (smart epoxy?) and begin dumping khaki goo onto the skin. The heat generated by pulling the hull apart would probably be noticable but there might be ways of mitigating that somewhat (though probably impairing the efficiency of the disasssemblers at the same time).
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Tue, 2010-08-31 16:39
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
The Doctor wrote:
The heat generated by pulling the hull apart would probably be noticable but there might be ways of mitigating that somewhat (though probably impairing the efficiency of the disasssemblers at the same time).
This assumes that the hull can be digested exothermically. If it is just iron or silica (or carbon in vacuum), you need to provide energy to the disassemblers to do their work.
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Wed, 2010-09-01 19:52
Xarei Xarei's picture
Re: Space naval combat (Segway from Antimatter thread)
I've been musing on the difficulty of safely venting heat and disguising drive output. One thing that came to mind is that it might be possible to utilize controlled interference from multiple sources of emission to disguise the exact location of the emitter. The simplest example would be two heat vents projecting infrared at 1000nm wavelength in a 180 degree 'fan' that were exactly 1000nm apart. From a perspective in line with the two emitters there would appear to be no radiation due to destructive interference, whereas from other vantage points constructive interference would reveal the output. It would seem that slightly but continually modulating the distance between the emitters you could prevent a sensor at any given vantage point from receiving total information. The obvious difficulty with this idea is that with enough sensors out there (especially if they communicate with Qbits) it would still be quite possible to divine the location and current velocity etc. of the ship.
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Thu, 2010-09-02 03:31
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
Xarei wrote:
The simplest example would be two heat vents projecting infrared at 1000nm wavelength in a 180 degree 'fan' that were exactly 1000nm apart. From a perspective in line with the two emitters there would appear to be no radiation due to destructive interference, whereas from other vantage points constructive interference would reveal the output. It would seem that slightly but continually modulating the distance between the emitters you could prevent a sensor at any given vantage point from receiving total information.
But if you have a perfectly defined frequency the entropy of the radiation is going to be zero, so it cannot get rid of any waste heat. Blackbody radiation (which I assume has maximal entropy) on the other hand is incoherent and multispectral, so you cannot get any good interference to hide in.
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Thu, 2010-09-02 13:00
Xarei Xarei's picture
Re: Space naval combat (Segway from Antimatter thread)
That's definitely a good point about entropy, but I'm not sure the emitters need to be perfect. The destructive interference just needs to lower the 'profile' of the emission to the point where a sensor can't distinguish it from background radiation. Now the background radiation in space is pretty low, so that's not necessarily a lot of room for error, I suppose it depends on how far thermometer accuracy has improved in EP. Taking a brief look at modern thermometers shows a precision of around .1 degree C at the incredibly low temperatures we are talking about, so that might give some leeway. In trying to go farther with this whole destructive interference idea, I seem to have run into the edge of my physics knowledge... I realized that I was not sure whether or not you could actually propel a ship if all that it was emitting was photons. On the one hand photons are massless, but on the other hand there is radiation pressure. Whether you could generate reasonable delta-V is a whole other question, I'm just wondering if you could move at all?
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Thu, 2010-09-02 16:56
Arenamontanus Arenamontanus's picture
Re: Space naval combat (Segway from Antimatter thread)
Xarei wrote:
Taking a brief look at modern thermometers shows a precision of around .1 degree C at the incredibly low temperatures we are talking about, so that might give some leeway.
The WMAP satellite has a sensitivity of around 1 milliKelvin per second in its measurements of the cosmic microwave background, so we should expect EP sensors to be at least that sensitive.
Quote:
In trying to go farther with this whole destructive interference idea, I seem to have run into the edge of my physics knowledge... I realized that I was not sure whether or not you could actually propel a ship if all that it was emitting was photons. On the one hand photons are massless, but on the other hand there is radiation pressure. Whether you could generate reasonable delta-V is a whole other question, I'm just wondering if you could move at all?
You can definitely propel a ship with just photons: consider a solar sail. A magical antimatter rocket that just radiated gamma straight backwards would be really efficient - the faster your reaction mass is moving the better thrust you get, and light is the ultimate in this regard. The problem is that stealthing ships by radiating away energy so that enemy sensors fall into interference fringes probably doesn't work for simple geometric reasons. You need to keep the enemy in these bands, but you may not know or control how he is moving. He might also be far away, meaning that it matters where your fringes were at the point in time he is seeing - you would actually need to steer in certain directions to keep him in the dark, quite likely forcing you to move somewhere you don't like. Now add a second enemy sensor moving independently...
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