Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: Aardwolf on August 25, 2010, 10:09:07 pm
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In a "realistic" space warfare scenario, how can you possibly get the enemy to "lose your trail" once you've been spotted? Assuming of course that once one enemy spots you, they inform the rest of the enemy ships / observation network. This is really bad for your attack craft, because once they get spotted, either they have to stay on the field until they're dead, or return to their base as the bringer of death; as soon as the craft returns, the enemy which was watching that attack craft now knows where your base is, and can either blast it at long range with lasers, or track anything else deployed by it (and then hit any places those ships return to, along with the base they had previously spared).
I've got an idea how you might do it but I wonder what you guys can come up with.
But first: no FTL, no handwavium, and no violating the laws of thermodynamics.
Edit: removed spoiler tags. My idea was this:
Jam the bastards! If all their sensors can pick up is a blinding white / static, they can't track you! Hopefully...
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one would have to assume there is a practical limit to the range of detection. i imagine it would be much like air or naval combat today, just on a larger scale.
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Put something between you and them. Preferably a star, but a planet might work.
Beyond that, jamming's more or less it.
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Assuming that they can't see you from far off, you could: destroy what spotted you, drop a nuke (for interference), and run like Hell, as it were.
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There's nothing that will work short of physical occlusion.
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Well, unlike air and naval combat, there's no air to degrade the signal quality. At worst, it decreases a tiny bit worse than 1/r2 for passive sensors, and 1/r4 for active sensors.
That, and there's no horizon blocking your line of sight... unless you do what NGTM-1R suggested, of course. But then you have to pray that their distributed sensor network doesn't include anything on the other side.
Depending on the extent of their surveillance network (ships, sensor stations, dirt-cheap unmanned probes, etc.), the people watching you might have a limited "surveillance budget"... it would probably be easier for each node to track stuff closer to it, and if everything's focusing on tracking the one attack ship that just unloaded its payload on your colony, it's not focusing on tracking the ship that's got a full payload ready to drop on something else... Still, even if they had a very small surveillance budget, you could never be sure they weren't still tracking you (unless they're somehow incapable of using anything other than directional active sensors, of course).
Edit: In response to the stuff that was posted while I was typing (specifically Battuta's comment about physical occlusion)... even then, you can't be sure.
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invest in weaponry that has a longer effective range then your opponent.
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Sensor decoys
Clone your own ship causing multiple targets
The previous mentioned kill them
Jammers
Outrun them
Broadcast porn on their radar frequency.
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Broadcast porn on their radar frequency.
I like the way this man thinks.
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The only effective stealth in space is moving towards your opponent's sensors at speeds only somewhat slower than the speed of the signals you give off.
This is why space warfare between any reasonably advanced 'real' species would simply become mutual destruction with RKVs. Inevitably all objects in predictable orbits (including planets) would have to be abandoned.
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They could also follow your propellent trail.......
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They could also follow your propellent trail.......
That's pushing it more than a little. Particularly if you're not actively burning.
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The only effective stealth in space is moving towards your opponent's sensors at speeds only somewhat slower than the speed of the signals you give off.
This is why space warfare between any reasonably advanced 'real' species would simply become mutual destruction with RKVs. Inevitably all objects in predictable orbits (including planets) would have to be abandoned.
Yeah, I was thinking that. As soon as it became a "total war" scenario (i.e. where you're willing to obliterate cities or colonies), planetary colonies would just get obliterated by lasers at maximum range. A city can't jink, after all. Only a REALLY thick atmosphere could protect you, I think... maybe Venus or Titan. You might be able to dig deep enough underground on other planets that you could withstand bombardment, but then you have the trouble of not being able to dig back up (due to the enemy controlling the surface). And even if you dig really deep underground, they could always just make bigger bombs. Or gopher-bombs!
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A few things to think about before we fall into the avoiding detection is impossible trap
what transit speed are we talking for the sensor signals? if we are talking EM frequency based systems then at 1 AU distance you have a there and back time of about 16 minutes.
also what about things like solar ejecta and gravitational distortion of the signal
finally we don't know what hull materials / energy shield systems space ships will employ and what sensor defeating properties they will have
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Cloak and quote Shakespeare at them.
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Only one problem.
Stealth for atmospheric craft is easy. There are two ways of detection, optical and radar (there's also audio, but we'll ignore that for now). To defeat optical detection, you need to have a paint scheme to blend into your surroundings.
Then there's infrared detection. You cannot fully defeat that, but you can reduce the risks by employing exhaust cooling mechanisms (Look at the Apache Gunship, the F-117 or the B2 for examples). If you're moving very fast, atmospheric friction will also screw you over, as the SR-71 proves.
To defeat radar, you can either absorb the radiation (heating up in the process) or scatter it.
Now. As we can see, stealth is a function of how well you can blend in with your surroundings. Let us now consider space. If our proposed stealth spacecraft is in front of empty space, it will stick out like a sore thumb on infrared, as it will be considerably hotter than its background. In addition, radar backscatter (which can only be reduced, never absorbed completely) means that you can safely treat any radar target you get as a threat (and micrometeorites are a large enough danger that you need to do that anyway).
Now, you speak of stealth fields and energy shields. Here's a hint. As long as you are emitting something, you are not blending in with the empty space surrounding you.
You can, of course, hide behind another celestial body. That will always work. You can't, however, hide in front of another celestial body (although it would work provided the distance between you and the target is big enough). All the emission-suppressing stuff you've been doing to blend in with empty space? Won't help you if you're hiding in front of a planet. You'll still stick out, simply because you'll be much colder than your surroundings.
Hiding in front of a star is easier as the star will blanket your emissions IF you are far enough away from your target.
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Decoys, tons of them.
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I tend to think your best bet is automated warships. So for example you were going to attack some system, you would need to begin the operation at least six months or so before your attended attack time. Your warships would be accelerated into whatever trajectory led them to your desired attack positions, most likely around the major planets/colonies rough patrol areas. They would then pretty much completely cut all power prior to detection range and coast in. Some kind of timing device would be needed, lets say something analog and automatic for no energy emissions set to wake the ship after the time for reaching the activation area had expired. The ship would need to cold start all its systems, identify and attack targets hopefully before it is destroyed.
That said unless all parties are suicidal space warfare probably needs to be relegated with strict and specific rules of engagement, otherwise the first war will be the last.
P.S. Decoys probably won't work (http://www.projectrho.com/rocket/rocket3w.html)
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If we are operating a high probability of detection and a sub-light craw into the system scenario then I would have to look at ignoring obtaining space superiority as a 1st objective.
I'm thinking using something StarSlayer's drone concept with 2 components to the "fleet"
Component 1: The principle component of the fleet being a swarm of "smart" missiles who arrive in system, identify pre-programmed and/or targets-of-opportunity such as space installations, settlements, mining operations etc and attack using explosives, one shot energy weapons, chemical/Biological payloads. auxiliary armament would be a small scattering of point defence weapons but mainly relying on evasive measures to deliver the attack.
Component 2: is a covering fleet programmed to shadow the missiles and act in their defence using a mix of heavy weapons to bring down large threats and faster tracking weapons to provide 1st line close defence against small craft and missiles.
Should the second component detect a retreat in enemy occupation of the system then have them signal that fact to us and we then deploy a more versatile occupation fleet
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go to the far side of Jupiter and wait for **** to blow over (your buddies will have to tell you when it's safe)
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Throw asteroids at them
From the other side of the galaxy
Also, remain in tight formation when in orbit, there's not much room to maneuver up there.
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Escape path through minefields/other traps.
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Throw asteroids at them
From the other side of the galaxy
Also, remain in tight formation when in orbit, there's not much room to maneuver up there.
By shooting the asteroids with plasma out of your ass?
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Throw asteroids at them
From the other side of the galaxy
Also, remain in tight formation when in orbit, there's not much room to maneuver up there.
By shooting the asteroids with plasma out of your ass?
exactly.
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Let's get the crud out of the way:
1. There is no stealth in space.
Thermodynamics say so. Check Project Rho for this has been debated and debunked to death. No stealth in space as long as you play by the rules of physics.
2. Decoys don't work. Any decoy that could fool your opponent will cost as much as a ship.
Newton says and thermodynamics say so. If your exhaust is of T-temperature and of L-luminescence, then you're outputting F-force. If F is smaller than what a ship would need then it's a decoy. If your decoy is as heavy as a ship and needs an engine just as big as a ship's you're better off building a ship anyway.
3. Weapons are more important than the platform they're mounted on. A space laser can have an effective range measured in light-minutes. Kinetic weapons and missiles have *unlimited* range. Provided you can push them hard enough, you could hit a target from half across the solar system.
4. Hitting is more important than destructive potential. If you can't jink you'll be hit.
There are four (and a half) kinds of weapon:
-Lasers (infra, visible, ultraviolet, X-ray). Their range limited by diffraction, but they'll have the best hit-to-miss ratio as they're light-speed weapons.
-Kinetics are rocks or metal thrown hard. Actually your biggest weapon is the ship's engine. Kinetic energy is a *****. You don't need a multi-ton railgun when your target's already on a reciprocal orbit of several hundred km/s. Kinetics have the worst hit-to-miss ratio as they can't correct their course and a maneuvering target can avoid them entirely.
They're the cheapest and *still* a weapon of mass destruction. Throw some big chunks of rock from higher up the well and gravity will give your rocks all the "OOMPH!" you need.
-Particle beams are the bastard child of kinetics and lasers, but in practice are more like short-legged lasers than kinetics. They have worse hit-to-miss ratio than lasers, but pack a bigger punch. (Ion canons are actually particle canons). They're c-fractional weapons that is most designs have their shot travel at a considerable fraction of the speed of light.
-Missiles fix the worst drawback of all your other weapons: they can react to your target as they get new data. They have practically unlimited range as you can build multi-staged or re-ignitable engines and can make them coast for a portion of their flight. Whether a missile can intercept a ship is the very same question whether a ship can intercept another. Both fall under the same restriction of space design (fuel-fraction, engine specific impulse, maximum thrust).
-Missiles could mount a variety of warheads and therefore use the best abilities of other weapons. You could mount nothing and let kinetic energy do its work however *hitting* a jinking target is really hard. You could mount a nuclear warhead, but with no medium to transmit the shock wave you'd still need to be within a couple of km-s of your target for radiation pressure to do the damage. Finally you could mount a bomb-pumped laser on the missile and get a weapon that both has an practically unlimited range and a light-speed weapon that's impossible to dodge if you're closer than a couple of light-seconds (the actual range depends on the target's ability to dodge).
-If you mount a conventional laser on your missile you end up with an automated ship, a "drone".
About weapon design:
-Kinetics could be nothing more than chunks of rock tied down and released from their harness.
-Particle beams would likely need a particle accelerator (either a helical or a linear design) so they'd be both bulky and heavy, since you can use magnetic fields to shape the particle stream it could have a small cross-section.
-Lasers will be big and have a great cross section as their range depends on the diameter of their main mirror used for focusing their attack beam. This could be a highly polished and expensive main mirror, a composite design that would be less effective but easier to maintain and repair... or even a throw-away external design that's only good for a couple of shots. Both have their pros and cons, but here's the main deal: if your ship uses a laser there's no logical reason not to build it as big as possible so it has a greater range. Therefore the laser will take up a great deal of your mission section. (While -as usual- propellant will take up the bulk of your ship).
Lasers vs Kinetics vs Missiles:
-There's a good parallel between the various weapons: A cop has a pistol that can hit a felon far away. This is the laser. He also has a shotgun that does a great deal more damage, but it can't hit objects far away. These are kinetics. (The picture is not entirely correct though as kinetics are highly speed dependent. On opposite orbits they're devastating... however if the combatants are on similar orbits they loose a great deal of their destructive potential). He also has a police dog, that he can set loose and it will track down the felon on its own.
The picture is correct as far as that the felon could also have all of these and he could shoot the dog with either his shotgun (kinetics) or his pistol (laser).
What's not accurate though is that lasers can also shoot down kinetics with impunity. The battle between "orange" vs "purple" has been long waged and the answer as to which is better: ...it depends.
A laserstar (a spaceship with a laser primary weapon) will likely be several magnitudes more expensive than a kinetistar (a spaceship with a kinetic primary weaponry). The quesiton whether kinetics have a chance depends on how much mass you can bring against the laserstar and how fast the later can jink.
If you're up to GW output levels of engines that can do full G-s of sustained thrust (torchships!), then kinetics have no chance... however in a more probably (for the early space future) mili-g powered ships with nuclear-electric engines they *do* play.
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Actually, there could be stealth in space if the detection methods were not thermal based detection methods.
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Lies that's what heat sinks are for!
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Actually, there could be stealth in space if the detection methods were not thermal based detection methods.
But why wouldn't you use thermal detection methods if they work so well?
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saturated environments.
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I would think stealth technology might be possible to implement, but only if you have a fairly good idea from what direction you are going to be observed. It is possible to cool the forward facing quarter of the ship to "ambient" temperature, but that means your heat sinks are going to have to work overtime to dissipate waste heat in a direction no one is expected to be looking from. If there is a chance of being observed from more than one angle, that trick will not work for long if at all.
I can see it working to mask your approach to a star system as long as you are coming in unpowered and ballistic. Once you get close enough, if they are looking from more than one location, the thermal signature from your heat sinks will show up whether you are coming in under power or not.
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if you know the direction of the enemy vessel, couldn't you pump the heat away to the far side of the ship?
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</hivemind>
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We are Hugh.
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if you know the direction of the enemy vessel, couldn't you pump the heat away to the far side of the ship?
You could.... but where is the enemy? If stealth is possible, it would be possible for everyone, meaning you wouldn't be able to find a direction that is safe for you to point your radiators in. There would always be the risk of you pointing your exhaust right where an enemy can see it.
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Some direction is better than no direction at all. Besides which, if an enemy can see your directional exhaust, he could always have seen your non-directional exhaust had no attempt at stealth been made.
It's a "risk" with no net negatives, and only gain.
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the original question was could you lose someone, if you are trying to lose someone that implies you know where they are, or at least have a good general idea.
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I don't think it's possible.
If your drive is off you are on a ballistic course and can be vectored and intercepted (since they have, in this scenario, detected you.) In order to alter your course, you have to turn on your drive or thrusters, and will then be detected no matter how good your stealth is unless you have some kind of terribly passive drive system that doesn't scatter (I have no idea what that would be.)
Even so, you need to cool your hull to around 2 Kelvin, and I simply don't see any way to do that.
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you use magnetic acceleration to fire 2 degree Kelvin metal pellets, altering your trajectory, getting a thin film of metal on the outside of your ship that cold seems like something that might be possible by the time we have to worrying about our space ship evading another space ship's weapon and tactical sensor systems.
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you use magnetic acceleration to fire 2 degree Kelvin metal pellets, altering your trajectory, getting a thin film of metal on the outside of your ship that cold seems like something that might be possible by the time we have to worrying about our space ship evading another space ship's weapon and tactical sensor systems.
I don't think it'd work. Putting a cold thing in front of a hot thing is not going to conceal it because heat in space is radiative.
Check out the Project Rho page, it has a long discussion on the topic.
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Not only that, but if you're firing 2K projectiles, you're going to be expending energy (and thus generating heat) to cool the projectiles...
Once you're caught, you have two intelligent options...
(A.) Turn N' Burn (run away!) - and try to get away from your attacker to a safe locale...
Or...
(B.) Turn N' Fight!
Obviously, the considerations now fall into what your ship is armed with, how it handles (accelerates, etc.), and what consumables you have (fuel, life support, ammunition). Then, you must consider the same thing for your opponet. I think it's also a great idea to also realize that super sensors are kind of being overplayed - there's lots of really large things out there we don't know about even in our current situation of understanding our solar system. Being stealthy will most likely rely on the ship commander keeping in mind where his enemy is, how to avoid him, and how to stay as far away as possible. Any emitter (sensor, etc.) will lose intensity/signal strength over extreme ranges. Being an irregular, moving target will also make a ship hard to catch - ships are also likely to be pretty small in comparison to the large objects we spot moving around in space - you know, big rocks? ;p
That said, being picked up by an enemy might imply that you're close enough for whatever enemy you're dealing with to actually open up on you. If you've had this happen to you... Well, your technique was wrong, that's all. :lol:
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heat in space is radiative, so if you put something cold between a sensor and something hot all the sensor will see is cold, it's not like it's going to see 'hot' vacuum.
heat generated by the refrigeration system for the stealth propellant and the magnetic impulse system will be directed away from hostile sensors
you turn your ship in the general direction of your base, turn your thrusters to max burn until you reach a good speed, obviously evading attack that might be launched at you, once you reach a cruising speed you turn your stealth system on, that disables all high energy systems and refrigerates the back side of your ship. you use a mass driver that fires small same-temp-as-space pellets to apply course corrections.to get you at the very least not on the same trajectory you were on when you were doing a high thrust burn away from your pursuers. the only thing not currently feasible with our level of technology is a refrigeration system that can cool the hull of a ship down to 2K, but it is not physically imposable.
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What about laser propulsion? If you do it right, it could only be spotted from (almost) directly behind (and then you'd be dead)
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well being as how lasers are massless, i'm not really sure how that would work.
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well being as how lasers are massless, i'm not really sure how that would work.
Oh, you poor fellow. :p
Don't you know how a solar sail works? It's not by solar wind (common misconception, that), it's by light pressure. Light has momentum.
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granted, but GENERATING the light with the miniscule momentum doesn't sound practical to me.
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Even so, you need to cool your hull to around 2 Kelvin, and I simply don't see any way to do that.
Since I have friends up at Palomar Observatory, I can state that this isn't really true. 50 or 100 Kelvin is a much more realistic figure for obscuring your radiated heat from instruments that could be practically mounted on a manned or unmanned missile truck for space combat. Anything else is too large, too sensitive, and far too easily burned out by an opponent with IR-frequency laser pointer (I'm not joking about that, someone wrecked a 50k infrared camera once with a laser pointer from a couple miles away) and half a brain.
If you go ultrasensitive thermal, a few minutes after mutual detection you both go blind. They can afford to saturate your possible courses with infrared "spots" because it's not very power-intensive to damage a sensitive instrument. Granted, cooling to 100 or 50 Kelvin is still a big problem.
There's also tradeoffs that would have to be made between field of view and effective detection range if you want to look deeper than a couple AU.
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That's in a ship-to-ship engagement, but anyone smart is going to have a lot of passive thermal detection on drones or whatever.
And like you said, cooling the ship to 50 or 100 is not going to be easy either. Overheating is a huge problem in space.
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heat in space is radiative, so if you put something cold between a sensor and something hot all the sensor will see is cold, it's not like it's going to see 'hot' vacuum.
Yeah, it's just going to see the glare of the radiated heat through your screen of cold metal pellets, which are never going to be thermally opaque.
heat generated by the refrigeration system for the stealth propellant and the magnetic impulse system will be directed away from hostile sensors
See Project Rho. I recall it doesn't work.
you turn your ship in the general direction of your base, turn your thrusters to max burn until you reach a good speed, obviously evading attack that might be launched at you, once you reach a cruising speed you turn your stealth system on, that disables all high energy systems and refrigerates the back side of your ship. you use a mass driver that fires small same-temp-as-space pellets to apply course corrections.to get you at the very least not on the same trajectory you were on when you were doing a high thrust burn away from your pursuers. the only thing not currently feasible with our level of technology is a refrigeration system that can cool the hull of a ship down to 2K, but it is not physically imposable.
Yeah but then you run into a wall of sand somebody puts in front of your incredibly limited future position cone.
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That's in a ship-to-ship engagement, but anyone smart is going to have a lot of passive thermal detection on drones or whatever.
Which have to transmit somehow or they're useless, and are equally susceptible to being blinded for that very reason. Unless you want to put them on a really long wire.
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That's in a ship-to-ship engagement, but anyone smart is going to have a lot of passive thermal detection on drones or whatever.
Which have to transmit somehow or they're useless, and are equally susceptible to being blinded for that very reason. Unless you want to put them on a really long wire.
Yeah, but again, you only have to vector the target once to get a pretty good paint (most 'realistic' ships don't have anywhere near the kind of delta-V to make rapid course changes) and your remotes can use laser signals, which are pretty hard to pick up.
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That's in a ship-to-ship engagement, but anyone smart is going to have a lot of passive thermal detection on drones or whatever.
Which have to transmit somehow or they're useless, and are equally susceptible to being blinded for that very reason.
Well yeah, in order to share their findings they have to transmit. That transmission is probably omnidirectional, rather than being beamed directly toward some command post (then you'd have the advantage of not revealing your sensor's position as much, but you'd be revealing where your command post is when they manage to detect it), so the sensor is now a target.
So make them as cheap as possible.
And maybe set them up so they can be remotely switched from a passive mode to active mode once you figure they've been spotted anyway.
Edit:
Oh right, lasers for transmitting the data.
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Edit:
Oh right, lasers for transmitting the data.
Laser comms are probably a bad idea in a situation where you are required to A: manuver radically to avoid destruction and B: light lag is a factor.
In essence, if you are manuvering enough to avoid being skewered by enemy lasers, you are also manuvering enough your drones won't be able to reliably signal you with a directional beam. It has to be omni. Even a semi-directional transmission cone would require you to squawk yourself on a fairly regular basis and invite dire consequences if your cryptology isn't up to the task.
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Ah, but this is a sensor drone/platform/probe.
It only ever needs to send (well, almost), and if it's using a laser, when it does send, it (probably) doesn't reveal its position. And since it's unmanned, it doesn't need to keep humans at livable temperatures. So it's cold. Stealthy. No need to be maneuvering and avoiding enemy lasers if they don't even know where you're watching them from.
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You misunderstand me. I'm not talking about the drone. I'm talking about your weapons platform to which the drone is actually transmitting, which has either been fried by enemy lasers or to which the drone cannot transmit using a form of completely undetectable communications like laser comms because it can't predict where it's supposed to be transmitting to.
So the drone has to squawk. And then it will be vunerable to either blinding or destruction.
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Your whole scenario is silly. If you're evading lasers you know exactly where the enemy is because he's shooting lasers at you, so you don't need the drone at all!
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Again, the implications so far have relied on the "super sensor" scenario, which also seems to imply the given region is perfectly observed or defended. Over a truly massive region, this simply is not feasible, at least not on a scale with "sub-FreeSpace tech," which of course does not have access to magic or unobtanium.
Being "stealthy" in space really comes down to avoiding major "control points," such as planetary orbits, etc. The problem is thus that to engage the enemy, you will need to encroach upon such positions...
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Again, the implications so far have relied on the "super sensor" scenario, which also seems to imply the given region is perfectly observed or defended. Over a truly massive region, this simply is not feasible, at least not on a scale with "sub-FreeSpace tech," which of course does not have access to magic or unobtanium.
Being "stealthy" in space really comes down to avoiding major "control points," such as planetary orbits, etc. The problem is thus that to engage the enemy, you will need to encroach upon such positions...
As Lex Luthor would say, wrong!
Something as teensy as the Space Shuttle's main engines can be detected, by modern sensors, from a range of several AU. Something realistic like a fusion torchship could be detected from Alpha Centauri.
As for the drone issue - your remote sensor platforms should simply fire whisker lasers at stationary (well, predictably moving) repeaters near your own ships, which could then rebroadcast omnidirectionally.
Again, that's with modern tech.
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Here is a related problem how much effort in computational power and staffing would it take to monitor a defence of our home system? also how many sensor locations would it take to have total coverage?
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Here's a thought: unless we're talking about an unmanned drone, your ship will need to have sections at least 293 degrees Kelvin hot (20 degrees Celsius), so the hairless monkeys on board don't die.
...you'll have to do something with that heat.
As to "directional radiators": How the hell do you know which direction is safe? Your enemy can be just as stealthy as you.
...and the bottom line: if you run your radiators cool, they'll be massive. Bye-bye dodging incoming shots as you'd be too heavy to do so.
...and all the enemy vessels need is a separation of a couple thousand kilometers to get some scattered IR. Not too hard to do.
So:
Absolute stealth is impossible in space and even "practical stealth" is impractical as the benefits are far outweighed by the costs.
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at least 293 degrees Kelvin hot
lolwut?
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Your whole scenario is silly. If you're evading lasers you know exactly where the enemy is because he's shooting lasers at you, so you don't need the drone at all!
But since you cannot possibly evade them once fired, if you suspect there is an enemy ship in the area you would be conducting evasive manuvers as a matter of course. It's not silly; it's intelligent. :P
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Your whole scenario is silly. If you're evading lasers you know exactly where the enemy is because he's shooting lasers at you, so you don't need the drone at all!
But since you cannot possibly evade them once fired, if you suspect there is an enemy ship in the area you would be conducting evasive manuvers as a matter of course. It's not silly; it's intelligent. :P
But now you're ignoring one of the tenets of your scenario and one of the tenets of how lasers work, those being
1) you postulated light lag was a factor and ergo sufficiently enthusiastic evasives could slip a laser, because
2) lasers must remain on the target in order to achieve burnthrough in all but the most energetic configurations, and therefore rapid maneuvering and rotation are important even when light lag isn't a factor but especially when it is.
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And that ignores...how?
Recall we're discussing drones that other people are saying are stealthy/blahblah.
Also recall that your posist was they could mount more sensative instruments than the weapons truck. And I said why the weapons truck wouldn't want one.
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Well if you CAN possibly evade them when fired then saying that you can't possibly evade them when firing (as a way to
wait
I already said that the best course would be to have your remote sensors use lasers to transmit to repeaters aaaanyway.
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Here's a thought: unless we're talking about an unmanned drone,
My drone is unmanned. Your argument is invalid.
I already said that the best course would be to have your remote sensors use lasers to transmit to repeaters aaaanyway.
Or you could make the sensors dirt cheap, so cheap that they don't need to worry about being shot down because of how many of 'em you've got... and then use omnidirectional transmission... But then I guess the guys monitoring the drone chatter might have a hard time sorting out what's important.
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Well if you CAN possibly evade them when fired then saying that you can't possibly evade them when firing (as a way to
And I said that you can't evade a blinding laser because they can fire a hell of a lot more of them then a weapons level laser because they take very little power, thus making staturation of your possible courses simple.
I already said that the best course would be to have your remote sensors use lasers to transmit to repeaters aaaanyway.
Which then themselves would be destroyed first. :P
Your only real option is saturation of drones. Not even drones, really, fixed emplacements in fixed orbits in large numbers. Make it impractical to destroy them all. Of course, that's true of everything.
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Space combat is totally going to be lame...
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Well if you CAN possibly evade them when fired then saying that you can't possibly evade them when firing (as a way to
And I said that you can't evade a blinding laser because they can fire a hell of a lot more of them then a weapons level laser because they take very little power, thus making staturation of your possible courses simple.
Yeah but what's that going to do except tell you exactly where they are anyway?
I already said that the best course would be to have your remote sensors use lasers to transmit to repeaters aaaanyway.
Which then themselves would be destroyed first. :P
what is this
how
Your only real option is saturation of drones. Not even drones, really, fixed emplacements in fixed orbits in large numbers. Make it impractical to destroy them all. Of course, that's true of everything.
Fixed fortifications are monuments to the stupidity of man!
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I already said that the best course would be to have your remote sensors use lasers to transmit to repeaters aaaanyway.
Which then themselves would be destroyed first. :P
what is this
how
More specifically, how can they destroy the guns anyway if they cannot tell where they are?
The laser transmission ensures that both the sender and recipient are difficult to detect, unless you're within a narrow cone around the laser. Granted, you could get lucky, or your detection network might be huge enough to detect their detection network's transmissions every time...
Space combat is totally going to be lame...
Inorite? :(
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Yeah but what's that going to do except tell you exactly where they are anyway?
Make you go blind so you can't detect them. The laser flash destroying your ability to detect at long ranges doesn't occur to you? Isn't that what this whole discussion has been about?
what is this
Your logic failing. :P
how
They'd squawk to transmit where the target is and make themselves obvious targets in the process, since they're the clear weak link in the system.
Fixed fortifications are monuments to the stupidity of man!
what is this
And how is it relevant when they're not even fortifications? They're target saturation same as any other relevant tactic, and effectively the only useful tactic in this is target saturation anyways.
Or we could just put the system on the weapons platform itself and cut out all these middlemen who aren't really going to help.
More specifically, how can they destroy the guns anyway if they cannot tell where they are?
Because as I keep telling you and you keep failing to listen to, at some point somebody has to squawk omnidirectional to make the system work, and they in so doing will give their posistion away and become the natural targets. Someone has to be unsealthy to make this system of sensor drones and repeaters work.
The laser transmission ensures that both the sender and recipient are difficult to detect,
But won't get it to the guy with the weapons who is evasive, at random, and hence can't be transmitted to with a laser. Someone has to tell him, and that someone has to do so with an omnidirectional system to protect the weapons platform from being an easy target by having to stand still or hold a course.
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People, people... less quote warfare, please. You're antagonizing each other more than you're changing each other's minds!
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Jamming (as suggested by NGTM-1R) seems like a good idea, and hasn't been discussed much, despite my mentioning it in the first post (albeit in spoiler tags).
NGTM-1R, in response to your point about them squawking to transmit... I believe if the drones are using laser transmission, this could avoid the drones being detected. As you have pointed out, in order for the laser transmission to be received properly (without widening the cone and making it easier to spot), the recipient can't be jinking. So I ask, who is the recipient, and do they have to be jinking? Could a system be devised wherein the recipient does not need to be jinking?
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Depends. Can you devise a situation where the recipent won't be subjected to enemy weapons if detected? Manuver is your basic defense against being attacked by enemy weapons capable of relativisitic speeds like lasers, and to be safe you have to be manuvering when they arrive. And you're not going to see them coming, so you might as well just manuver constantly.
Jamming has dangers of its own in that missiles could be programmed to home in on the source, but deceptive jammers and trackbreakers should still be effective. However with no real reason to use radar for terminal homing (unless you can put your ship in front of a star or the sun side of a planet and it can no longer distingush an infrared target) the chances for it are few.
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Space combat is totally going to be lame...
Inorite? :(
Seriously. Give me the FS-verse over this whole mess any day of the week. :p
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As far as keeping the recipient alive... the recipient could have a preset flight pattern, known only to it and the sensor drones (obviously the sensor drones then need a failsafe to keep that information from being captured). Still, a recipient which has to maintain a flight pattern is going to be thrusting, which can be spotted even if the lasers can't.
Redundancy is probably a better approach. Have multiple stations/platforms/whatever listening to the sensor drones' data, and have the drones only ever transmit to one of them. The drones could additionally have a passive sensor to watch and verify that the monitoring station hasn't been incapacitated somehow. If it determines the monitoring station is out of action, it'd find the next available recipient (maybe randomly, or maybe by some "smart" algorithm).
One more thing: the sensor drones probably shouldn't be transmitting constantly. I reckon they should be on "quiet" mode until they detect something of interest, and only then should they begin transmitting (and then they should only transmit in short bursts, at irregular intervals). They might also monitor other sensor drones nearby, and coordinate which one should do the squawking somehow, so that they don't all go into "noisy" mode at once and thus don't all get shot down at once. This coordination would optimally be done with as little detectable transmission as possible; if the drones are in close enough proximity to each other, they might even be able to do some sort of "hand gestures" (I don't know of a technical term for this... basically something that you could see if you were watching through a small telescope, but which nobody else would see if they weren't already looking in the right place. And the data it conveys would be as useless as possible to anyone watching it that shouldn't be watching it)
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Because as I keep telling you and you keep failing to listen to, at some point somebody has to squawk omnidirectional to make the system work
why? why why
makes no sense
You have drones. They shoot lasers at each other. Eventually one of them shoots a laser at your home ship. It could be a few thousand kilometers from your home ship at that point, though it doesn't need to be; you cannot alter your velocity with any sort of speed in any way that will make a laser miss even at a vast range. Your whole scenario is contingent on the notion that some kind of unpredictable evasion is possible; it's not particularly. The best defense against lasers is, ironically, spinning.
If you are somehow maneuvering hard then you have enough drones that the later links are sufficiently close to your home ship to laser you. Not hard. Not at all. No omnidirectional squawking involved.
That said all this is basically irrelevant. You don't need the daisy chain at all. You need one drone and it needs to get one contact report and transmit it. It doesn't matter if it's destroyed after that. No realistic ship has enough smash to alter its velocity after that to make any meaningful difference to the subsequent engagement in any near-future setting.
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Battuta, although your laser transmission scheme makes sense, I do not believe it is necessary. If the sensor drones are sufficiently cheap and sufficiently numerous, an omnidirectional 'squawk' would at worst lose you a single drone, unless prior to this the enemy was completely oblivious to your observation.
Furthermore, I am not sure how wide of a cone the laser beam would be detectable within, although I imagine there would be some 'leakage', maybe a degree (angle measure) or so around the beam. In that sense, an omnidirectional squawk might have the benefit of not revealing the recipient. That said, narrow cone or not, the volume is still immense (although perhaps not infinite)... finding the target of the laser might not be feasible, either.
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Battuta, although your laser transmission scheme makes sense, I do not believe it is necessary. If the sensor drones are sufficiently cheap and sufficiently numerous, an omnidirectional 'squawk' would at worst lose you a single drone, unless prior to this the enemy was completely oblivious to your observation.
That's what I said in my last post.
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Yes, I was "running with it"
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You have drones. They shoot lasers at each other. Eventually one of them shoots a laser at your home ship. It could be a few thousand kilometers from your home ship at that point, though it doesn't need to be; you cannot alter your velocity with any sort of speed in any way that will make a laser miss even at a vast range.
Because they know where your home ship is. All of them. Without being told. So they know where to transmit to to pass it on. And they know where to do everything else without being told! Because it's magic!
Since you've already rejected the concept of placing them in fixed orbits earlier in the thread the weapons platform itself is going to be confused as to where they are and in order to "hook in" will have to talk to them somehow.
I'm sure this has occurred to you somewhere...oh wait it hasn't.
Your whole scenario is contingent on the notion that some kind of unpredictable evasion is possible; it's not particularly. The best defense against lasers is, ironically, spinning.
Then your scenario is equally useless as all that retransmission time works against it. While someone is heating your hull.
If you are somehow maneuvering hard then you have enough drones that the later links are sufficiently close to your home ship to laser you. Not hard. Not at all. No omnidirectional squawking involved.
Except for the connection phase. Also the ship would over time have to periodically update them and the drones themselves are in motion.
That said all this is basically irrelevant. You don't need the daisy chain at all. You need one drone and it needs to get one contact report and transmit it.
I've been saying that all along dammit. :P However if you can have one why not have more than one? There are other reasons your first salvo could fail.
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You have drones. They shoot lasers at each other. Eventually one of them shoots a laser at your home ship. It could be a few thousand kilometers from your home ship at that point, though it doesn't need to be; you cannot alter your velocity with any sort of speed in any way that will make a laser miss even at a vast range.
Because they know where your home ship is. All of them. Without being told. So they know where to transmit to to pass it on. And they know where to do everything else without being told! Because it's magic!
Magic would be helpful but unnecessary. The daisychain can stay in contact pretty easily.
Since you've already rejected the concept of placing them in fixed orbits earlier in the thread the weapons platform itself is going to be confused as to where they are and in order to "hook in" will have to talk to them somehow.
I'm sure this has occurred to you somewhere...oh wait it hasn't.
Uh yes it has, the whole point of them being able to pass reports is that they talk to each other.
Except for the connection phase. Also the ship would over time have to periodically update them and the drones themselves are in motion.
Mostly ballistic motion, not exactly hard to figure out. Believe it or not but real satellites do this!
That said all this is basically irrelevant. You don't need the daisy chain at all. You need one drone and it needs to get one contact report and transmit it.
I've been saying that all along dammit. :P However if you can have one why not have more than one? There are other reasons your first salvo could fail.
Sir, I dispute the fact that that's what you've been saying all along.
anyway stealth doesn't work in space
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Srsly guys, stop with the quote warfare.
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Ok uh... would a setup such as the following work?
1. An observer (could be sensor drones, or ships, or whatever) detect an enemy ship.
2. Regardless of whether the observer has been detected by the enemy, the observer then transmits to a friendly control center (ship or station where data is collected), which preferably is and will remain undetected by the enemy. If the observer matters (that is, you can't afford to lose it), then this transmission can be done via laser. If you don't give a damn what happens to the observer after it transmits, then you might as well just do an omnidirectional squawk. Or maybe it uses some sort of "hand gesture" system, readable from any direction but only if you've already got your telescope trained on the observer. Either way, the control center is still safe.
3. Now the control center knows where the enemy is. It can track the enemy as well as the observer, if not better (because it's designed to). It now begins tracking the enemy contact. The observer may now go on with it's business.
Note that the observer is not necessarily a 'focused' detection device like a telescope. It may be capable of focusing in on something like a telescope does, and it may do that whenever it spots a new contact, though.
The control center, on the other hand, is like a whole bunch of independent telescopes (or some similar sort of device(s)), which upon hearing about something, will point themselves at that something and not let it out of sight. Only one telescope (out of all of those on a control center) needs to be assigned to any one contact, except possibly as the contact moves out of view of one and into view of another. If there are multiple such control centers (which is probably a good idea), they can share some of their targeting data with each other (provided they can use some of the previously discussed "low profile" communication methods), so that if one goes down, the rest of them are still able to track (most of) its targets.
As for actually doing the attacking, the weapons platforms (lasers, missile pods, etc.) could and probably should be separate from the control centers. That way, you can attack without risking the loss of any more than that single platform.
Distributed and redundant systems FTW... then again, you probably won't trust an army of tiny robots to declare war or negotiate peace, so you still need to have some way of telling them what to do. Maybe just a failsafe, so if they're still floating around 10 years after the last friendly contact, they self destruct.
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NooOOOo do it so that if they ARE still floating around ten years without friendly contact, they must activate scorched earth protocol and avenge <strikethrough>me</strikethrough> their human masters.
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Why does the deployed sensor net need to be a "daisy chain" at all? Why not more like a neural network? Multiple paths back to the "home" ship. All communication could still be tight-beam to prevent detection. Active communication between nodes in the net to keep all elements apprised of position. I see minimal chance of the communication being detected. How likely is it for the enemy to fly right through a tight-beam in order to intercept the transmission? Even so, with sufficient encryption, the enemy still only knows the location of two elements of the net, and does not know whether they are merely sensor buoys or weapons platforms etc.
To me, it seems like redundancy is the best defense and offense.
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Meh, I'm tired of people regurgitating their "WW II U-boat/1990 Desert Strom in Space!" arguments again and again. Here are the facts:
1. Any object that is fast enough to evade a laser (even with light speed lag) will be detected.
2. Any object warm enough to house humans will be detected.
3. Jamming is useless. In space you don't need active detection as there is no atmosphere to degrade passive detection. Jamming can only effect active, ie. radar detection, but it just makes the life easier for your foe if they use passive detection.
4. Small stationary, really cold objects could be harder to detect - until they fire, then they light up like a Christmas tree. Thermodynamics says so. Any weapon that can hurt a ship will output enough waste heat so you show up.
5. ...to not light up, you'll need a *big* heat sink. Like an asteroid that will be detected anyway. Unless you're doing battle in the rings of Saturn that will be conspicuous anyway.
6. ...so all your transmission schemes are irrelevant as a maneuvering enemy can bypass your comm-net just by putting on a few km/s. You headquarter will show up anyway and will need to dodge either lasers of missiles if you're further back so you might as well put in on a warship that can dodge good.
So the final werdict:
Stealth is useless.
Stop trying to justify it, when you've yet to write a single equation. It's been done a thousands times and it has been proven *not* to work a million times.
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1. You don't have to evade if they don't know you're there, and they'll only know you're there once you start firing. By then it's too late.
2. You don't have to have humans to be dangerous.
3. That would only make sense if the jamming device is on the ship that's trying to hide. Obviously the jamming device is not going to be following along with the ship, it's going to be jettisoned as a decoy. Otherwise it's like trying to distract a guard dog by yelling "fetch the juicy steak" and then tucking the steak into your trousers and walking away.
4. By then it's too late. And maybe it's a one-use weapons platform anyway, so not only did they lose whatever I shot, but they also wasted a shot.
5. Or I can use unmanned throw-away vessels that aren't producing heat until they're firing anyway, and by then it's too late.
6. What? Bypass my comm-net? This makes no sense.
Stealth: Who's talking about stealth? Nobody here is talking about stealth except you.
Even if you can't be "stealthy", unless they've spotted your little blip on the infrared, and are actively tracking you, they've got a whole sky to search through. It doesn't matter that your thrusters are visible from Pluto if nobody's zoomed in watching that region of the sky in infrared. Just as a baseball field on earth can take a while to find in Google Earth, so too can a spacecraft evade detection in space. No "stealth" is required.
We've all (well, maybe 'all' is a bit too optimistic, but whatever) been aware of the effective impossibility of "stealthy" manned/armed/self-propelled spacecraft since before I posted this. The issue, if you had read the first post, revolves around the fact that once they notice you and start tracking you, there's very little you can do to get them to un-notice you.
Edited to fix 1 or more typos.
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Finding you is a *trivial* matter unless you do your damnest to hide your emissions. You people *still* don't realize that you're talking about fantasy scenarios from space-opera while the rest of us try to quote hard facts.
For God's sake stop spouting more of the same nonsense and read some solid science!
http://www.projectrho.com/rocket/rocket3w.html
http://www.rocketpunk-manifesto.com/2009/06/space-warfare-ii-stealth-reconsidered.html
Ken Burnside said:
Most of the arguments on thermo and space detection run through a predictable course of responses:
1) "Space is dark. You're nuts!"
2) "OK, there's no horizon, but the signatures can't be that bright?"
3) "OK, the drive is that bright, but what if it's off?"
4) "But it's not possible to scan the entire sky quickly!"
5) "OK, so the reactors are that bright, what if you direct them somewhere else..."
6) "What if I build a sunshade?"
7) "OK, so if I can't avoid being detected by thermal output, I'll make decoys..."
8) "Arrgh. You guys suck all the fun out of life! It's a GAME, dammit!"
Ken Burnside said:
A full spherical sky search is 41,000 square degrees. A wide angle lens will cover about 100 square degrees (a typical SLR personal camera is about 1 square degree); you'll want overlap, so call it 480 exposures for a full sky search, with each exposure taking about 350 megapixels.
Estimated exposure time is about 30 seconds per 100 square degrees of sky looking for a magnitude 12 object (which is roughly what the drive I spec'd out earlier would be). So, 480 / 2 is 240 minutes, or about 4 HOURS for a complete sky survey. This will require signal processing of about 150 gigapizels per two hours, and take a terabyte of storage per sweep.
That sounds like a lot, but...
Assuming 1280x1024 resolution, playing an MMO at 60 frames per second...78,643,200 = 78 megapixels per second. Multiply by 14400 seconds for 4 hours, and you're in the realm of 1 terapixel per sky sweep Now, digital image comparison is in some ways harder, some ways easier than a 3-D gaming environment. We'll say it's about 8x as difficult - that means playing World of Warcraft on a gaming system for four hours is about comparable to 75 gigapixels of full sky search. So not quite current hardware, but probably a computer generation (2 years) away. Making it radiation hardened to work in space, and built to government procurement specs, maybe 8-10 years away.
I can buy terabyte hard drive arrays now.
I can reduce scan time by adding more sensors, but my choke point becomes data processing. On the other hand, it's not unreasonable to assume that the data processing equipment will get significantly better at about the same rate that gaming PCs get significantly better.
Now, this system has limits - it'll have trouble picking up a target within about 2 degrees of the sun without an occlusion filter, and even with one, it'll take extra time for those exposures.
It won't positively identify a target - it'll just give brightness and temperature and the fact that it's something radiating like a star that moves relative to the background.
On the other hand, at the thrusts given above, it'll take somewhere around 2 days of thrust to generate the delta v to move from Earth to Mars, and the ship will be in transit for about 1-4 months depending on planetary positions.
Nyrath wrote:
The maximum range a ship running silent with engines shut down can be detected with current technology is:
Rd = 13.4 * sqrt(A) * T^2
where:
Rd = detection range (km)
A = spacecraft projected area (m^2 )
T = surface temperature (Kelvin, room temperature is about 285-290 K)
If the ship is a convex shape, its projected area will be roughly one quarter of its surface area.
Example: A Russian Oscar submarine is a cylinder 154 meters long and has a beam of 18 meters, which would be a good ballpark estimate of the size of an interplanetary warship. If it was nose on to you the surface area would be 250 square meters. If it was broadside the surface area would be approximately 2770. So on average the projected area would be 1510 square meters ([250 + 2770] / 2).
If the Oscar's crew was shivering at the freezing point, the maximum detection range of the frigid submarine would be 13.4 * sqrt(1510) * 2732 = 38,800,000 kilometers, about one hundred times the distance between the Earth and the Moon, or about 129 light-seconds. If the crew had a more comfortable room temperature, the Oscar could be seen from even farther away.
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I am familiar with projectrho. Stop assuming that, because you know such misconceptions exist, the people disagreeing with you must have them.
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So... summarizing...
It seems likely that a properly designed 'stealth' ship - remote or mostly remote controlled heavily insulated rock covered coasting thingamajig - would be able to approach far closer to the sensor site than regular ship. And deliver a barrage before being detected - with c lag it might be able to shoot several times before being spotted. But after the initial barrage there wouldn't really be any place for it to hide or shake the 'sensor lock' apart from going behind some bigger object.
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So... summarizing...
It seems likely that a properly designed 'stealth' ship - remote or mostly remote controlled heavily insulated rock covered coasting thingamajig - would be able to approach far closer to the sensor site than regular ship. And deliver a barrage before being detected - with c lag it might be able to shoot several times before being spotted. But after the initial barrage there wouldn't really be any place for it to hide or shake the 'sensor lock' apart from going behind some bigger object.
Even the first doesn't happen: to move into position it'd need to use an engine of some sort and then it'd be picked up.
...or it'd need to coast into position, however unless you can plan your engagement to happen months in advance that won't happen.
I'll grant you this: you might hide rockets or a laser or two on asteroids around a planet. However there's just so goddamn much space to cover that's it's unlikely that your emplacements would be in position to shoot. Furthermore anyone coming in may drop kinetic killers on all orbital emplacement as a policy as they too would be aware that you can hide nasty surprises on rocks.
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Lasers don't need to close the distance :p
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...remote or mostly remote controlled heavily insulated rock covered coasting thingamajig...
Even the first doesn't happen: to move into position it'd need to use an engine of some sort and then it'd be picked up.
...or it'd need to coast into position, however unless you can plan your engagement to happen months in advance that won't happen.
I did not say it would easy or very practical. Just that it should be possible within certain extent.
Also the all glorified RKV theory is flawed as it assumes that all warfare would total warfare in nature. Unrestricted by any laws or sanity. Same issue which governs the use of NBC weapons most likely affects RKVs as well. No one wants to conquer a nuclear or chemical wasteland or contaminated landscape. Same issue with RKVs... Impressive in theory but i doubt any sane strategic goal would include a step which renders the target planet uninhabitable.
The way i see the it...
Not big or fast enough RKV and it can be most likely shot or detonated to bits or diverted as case might be. Big and fast enough RKV to be able to ignore these threats and there is no longer any point launching it if you intended to actually land on the target planet within your lifetime. But that is already off-the-topic.
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...remote or mostly remote controlled heavily insulated rock covered coasting thingamajig...
Even the first doesn't happen: to move into position it'd need to use an engine of some sort and then it'd be picked up.
...or it'd need to coast into position, however unless you can plan your engagement to happen months in advance that won't happen.
I did not say it would easy or very practical. Just that it should be possible within certain extent.
Also the all glorified RKV theory is flawed as it assumes that all warfare would total warfare in nature. Unrestricted by any laws or sanity. Same issue which governs the use of NBC weapons most likely affects RKVs as well. No one wants to conquer a nuclear or chemical wasteland or contaminated landscape. Same issue with RKVs... Impressive in theory but i doubt any sane strategic goal would include a step which renders the target planet uninhabitable.
They'd work like nukes - deterrents.
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Lasers don't need to close the distance :p
They do. Their effective range is limited by diffraction.
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Well yeah, but unless you're a couple AU away, you're still dead.
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Ken Burnside said:
A full spherical sky search is 41,000 square degrees. A wide angle lens will cover about 100 square degrees (a typical SLR personal camera is about 1 square degree); you'll want overlap, so call it 480 exposures for a full sky search, with each exposure taking about 350 megapixels.
That gives 3.5 MPi per square degree, or 1871 lines per degree. This means each line is 2 seconds of angle wide, and a pixel is 2 sec by 2 sec. Wikipedia says the Moon is about 30 arcminutes in angular diameter, and it's 3474 km across. (http://en.wikipedia.org/wiki/Moon)
So in this scan, the Moon fits into a square that's 900x900 pixels, giving almost 4 km per line and 16 km^2 per pixel. If we parked the SJ Sathanas on lunar orbit facing Earth, it's 2.6 km by 2.8 visible part would have a surface of 7.3 km^2. That's less than half a pixel.
The camera will average out the temperature on the whole area the pixel covers. Let's assume that the ship has 280 K inside and absolutely no thermal insulation (giving it the 280 K on the outside as well).
If you're lucky, it'll be in a single pixel, and you'll get 7.3 km^2 with 280 K, and 8.7 km^2 with 3 K. The pixel will have a brightness of (7.3*280+8.7*3)/16= 129.4 K.
If you're unlucky, and the ship spreads out evenly on 4 pixels, it'll be a pretty cold object, with the 4 pixels at some 30-something K.
If you're very unlucky, and the ship has thermal insulation, and it's outside is hundreds of degrees colder than the inside (like a re-entering Space Shuttle, only inverted), it'll get below 10K.
Now if your ship isn't a Sath, but a GTF Pegasus facing the Earth.....
Nyrath wrote:
The maximum range a ship running silent with engines shut down can be detected with current technology is:
Rd = 13.4 * sqrt(A) * T^2
where:
Rd = detection range (km)
A = spacecraft projected area (m^2 )
T = surface temperature (Kelvin, room temperature is about 285-290 K)
If the ship is a convex shape, its projected area will be roughly one quarter of its surface area.
Example: A Russian Oscar submarine is a cylinder 154 meters long and has a beam of 18 meters, which would be a good ballpark estimate of the size of an interplanetary warship. If it was nose on to you the surface area would be 250 square meters. If it was broadside the surface area would be approximately 2770. So on average the projected area would be 1510 square meters ([250 + 2770] / 2).
If the Oscar's crew was shivering at the freezing point, the maximum detection range of the frigid submarine would be 13.4 * sqrt(1510) * 2732 = 38,800,000 kilometers, about one hundred times the distance between the Earth and the Moon, or about 129 light-seconds. If the crew had a more comfortable room temperature, the Oscar could be seen from even farther away.
Again, they assume the outside temperature will be the same as inside. Can anyone calculate how much power the ship would be emitting through thermal radiation if it had a sustained 280 K on the outside, in a 3 K environment?
Can anyone calculate how much energy an idling (running on full power) nuke reactor and 200 crewmen generate? We'd be able to figure out once and for all how warm the outside will have to be to radiate the surplus heat.
BTW- this time they're looking for it far more closely than doing a quick 4 hour scan of the sky with a 100 square degree camera described above.
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Thank you, BengalTiger, for doing that math for us. This was something I was thinking about from early on in this discussion (but didn't have any concrete figures for); even if a full-sky search takes however long, the resolution for that is limited. To get anything useful, you'd need to do a much narrower scan of the area around the little anomalous blip (your < 1-pixel-sized Sathanas, in the example).
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Or just use higher resolution cameras (or sensors or whatever). Which I'm sure we'll have by the time we start having serious space wars.
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Higher resolution requires more processing power (or more time to process). Obviously.
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Oh damn, too bad advancements in computer processing power have come to a stone cold stop. Oh wait, they haven't.
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OP specified no technical level of computational ability. I'd say it's a fallacy to assume best-case scenario in that department for the purposes of this exercise.
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So... what? Are basing this all on currently available technology? Can't we extrapolate how much computational power will increase in the future? I mean we're already talking about ridiculously powerful propulsion systems and radiators and stuff.
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can i just say all we have talked about so far is taking a snapshot of the sky, those readings then need to be analysed which takes human time and or additional computer processing/analysis
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can i just say all we have talked about so far is taking a snapshot of the sky, those readings then need to be analysed which takes human time and or additional computer processing/analysis
Not quite that difficult as space is cold, anything man-made is hot. You compare it to your charts for known objects and if something turns up it's a bogey...
...and paranoid captains will have the crew double-check the few objects in the vicinity anyway.
@Resolution debate: You don't get it. It's not about identification, it's about detection. Granted, if the bogey tries to blend into a nearby solar-body then this method won't work...
...except it will as it will likely be of different temperature.
...and using a sensor pod that's a couple of light seconds away is "impossible", you can't just make sure that a bogey can't hide in front of a solar body that way, that would be too easy. No we need some very expensive using unobtainium.
Still a sensor that's good for detecting things in deep space (in transit) would prevent all you stealth warfare scenarios as you'd see the bogeys coming in from a long way.
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Flaser, did you miss the part where a Sathanas would be smaller than a pixel, when it's only as far away as the moon? And that's something as large as a Sathanas, not a fighter or a missile.
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not to mention once detected you need to identify the object as friendly, hostile or neutral and IFF transmissions can be faked/copied.
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Alright, since noone figured out how warm an Oscar would be to get rid of excess heat, I volunteer to spend the next
few (dozen) minutes half hour to calculate it. I never did anything like this, so if I make a mistake anywhere- be sure to point it out.
The Oscar SSN has 2 pressurized water reactors, delivering about 73 000 kW each (shaft power). The highest efficiency for such a reactor is 32% (https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Pressurized%20Water%20Reactors.pdf). So running at full power, it'll deliver some 228 MW, of which 155ish is lost as heat, radiation, etc (let's say it's all heat to make stuff easier). If the ship's running without powering up it's nuclear rocket motors, let's assume the reactors run idling at 10% power. So that's 16 MW of heat per reactor.
So both reactors give a total of 32 MW of heat. Let's say the crew doesn't make enough energy to change the final result too much, so this is all the power that has to be radiated to space to keep our boat from overheating.
Now let's assume that the whole side surface of the ship is one ginormous radiator. The ship, as described a few posts earlier, is 154 m long, has a dia of 18 meters. That makes it's circumference around 18*3.14= 61 meters.
The total side surface, therefore is 154*61= 9394 m^2.
So we need to lose 32 MW in 9394 m^2. That's 3.4 kW per sq m.
Now, to figure out the black body temperature of our tub-of-war, I'll go ahead and use the Stefan-Boltzmann law, which states that the total power emitted from a black body (per square meter); known from now on as j is equal to the temperature^4 multiplied by the Stefan–Boltzmann constant, or sigma.
j= σT^4.
j= 3.4 [kW/m^2], σ= 5.7x10^-8 [W/(m^2*K^4)]
Therefore:
T= (j/σ)^1/4
T=(3.4/5.7*10^-8 [(1000*W*m^2*K^4)/(m^2*W)])^1/4
T=(3.4*10^8*1000/5.7)^1/4
T=494 K
Pretty dayum hot (especially when the reactor will have to run hotter than the coolant to give energy to it), and it shows how far we are from realism in our SWAGs in this thread.
It also shows that a 30% efficiency nuclear drive would totally suck on a space warship, unless it's OK to be detected pretty far away.
I'm also pretty sure that this ship would go 'below radar' for much longer than a Sathanas at nearly 300 K, so you'd really need a whole army of many thousand telescopes watching the sky to find it.
Now let's shut down the sucker completely. This time we have 100 crew members, each generating probably 500 watts of heat when sprinting from one end of the boat to the other.
That's 50 kW for 9394 m^2, or just over 5 W/m^2. The d00ds on wikipedia say that's below 100 K (http://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law). If the crew drops to 50, and they sit around making 200 watts, the boat would only need a few dozen K outside to keep from overheating, making it a much harder target to find than the 280 K that was expected in the texts about no stealth in space.
Now let's assume the nose cone gets totally insulated by a few yards of aerogel (and it could, because we have a realistic temperature on the radiators on it's sides that keep it from overheating). Without a space based system of sensors, or the ship flying to Earth sideways, it's just a very small, cold asteroid.
Now I'll make the ship with a 2x larger outside surface, and make it look like a disc (with the 2 sides being front and rear; defining "front" as the direction it's traveling).
I'll put all the radiators on the rear half. They'll have the surface of an Oscar sub, and they'll radiate heat with a temperature of under 100 K with the reactor off, just like the earlier cigar shaped vessel. And just like the Oscar, it has enough cooling not to overheat.
I'll put several yards of thermal insulation on the front half (aerogel is pretty light) to keep it from overcooling. Because the radiators are on the @$$ and the temperature is stable, the front could emit no energy at all. If the logic is correct, I now have a ship which is stealth (in space) in the front.
Now try to find me before I get past you, activate, and attack. :p
Hell, without the Solar system being saturated in sensors, I could simply keep facing the Earth using thrusters on the rear side and remain invisible.
My warheads could be smaller versions of the ship, and they can also be launched facing Earth. They'd make it all the way to reentry without being spotted.
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There's a lot of wishful thinking in there - but then again there's a lot of wishful thinking in the Project Rho calculations too. The truth is probably somewhere in between the two.
Your ship won't be able to get much of anywhere without giving its position away, but if it were launched from another rapidly moving object it might be able to coast in a stealthy fashion. Unfortunately incident solar radiation on the ship will render it thermally detectable inside about Jupiter orbit, so it better stick to the edge of the system. (Equilibrium temperature for a spherical blackbody around 1 AU is I believe somewhere near 300K).
The directional heat stealth might work at distances larger than that, though again the best the ship can do is glide.
You'd be best off ditching the crew. You could also get behind an occluding object, fire your thrusters there, and re-emerge gliding on a new vector.
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(Equilibrium temperature for a spherical blackbody around 1 AU is I believe somewhere near 300K).
True...
Earth's average temperature is 287 K. Mars has an average temperature of 210 K, and Pluto has 44- this will give a ballpark figure of how warm the side of the attacker facing the Sun will get, unless he/she/it/other is in a shadow or has a really high albedo or something. In that case it will be easy to attack- the defender's army of orbital telescopes will be far brighter than the attacker's fleet crossing Pluto's orbit. Even near Mars the attacker has a 100 K advantage vs illuminated objects orbiting Earth, and a sensor system covering the whole sky as far out as Pluto would require huge amounts of satellites (don't forget that all the data has to be processed). If they are insulated on the side facing away from Sol, they'd be just as invisible to the attacker as the attacker would be to them.
It looks to me that finding something in space isn't nearly as easy as it looks.
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Flaser, did you miss the part where a Sathanas would be smaller than a pixel, when it's only as far away as the moon? And that's something as large as a Sathanas, not a fighter or a missile.
No, you guys are the ones, who don't realize that for mere detection I don't need to get a "picture" at all, just a range, angle (~azimuth+elevation) and range rate. Sure, with a resolution of less then 1 pixel for freaking huge areas of space, my readings will suck - but that's fine! I've detected the bogey, I know *something* is there (I don't yet know if it's just a single source or multiple).
Even with only a single pixel to that whole area, the incoming reading will still flare compare to the environment, so I will get a definite reading that *something's* there.
Now I can slew my narrow angle targeting scope to the area and have a better look.