Macross Missile Spam -> The only way to go

[Lord Aurelius]

How big are the sensors needed to spot a shuttle RCS plume at the distance of Mars? Are we talking a liquid helium cooled infrared telescope, or a (large) solid state CCD like what FLIR uses in their cameras?

[SomeGuy12]

I'm saying that at interplanetary distances beam weapons (using technology we have now or in near future) are not feasible. There are too many issues for them to be an effective weapon that can be deployed on a spaceship.

1000m radius antenna? Come on. How do you turn that thing without it wobbling horribly out of shape?

Even if you could get a focused beam, pointing it accurately at a few million kilometers is going to be hard.

I agree. I guess what I was trying to get at is if you are thinking about going for a bigger mirror, or a petawatt of continuous beam power, the bigger mirror is a better idea.

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How big are the sensors needed to spot a shuttle RCS plume at the distance of Mars? Are we talking a liquid helium cooled infrared telescope, or a (large) solid state CCD like what FLIR uses in their cameras?

Yes, liquid cooled. It's not as bad as it sounds - the "liquid cooling" just means one of these is against the sensor. So there's a sensor, a solar panel for power, a radiator panel to shed the heat, and some kind of low-vibration pumping system. And gyros for orientation and RCS. Probably a spacecraft the size of a trash can or so. Basically, a mini version of the James E Webb telescope without the massive focusing mirror, just a small one.

[KerikBalm]

Which are the first targets to get blown up.

Sensor warfare isn't the same thing as stealth.

Rune is basically proposing using lasers to blnd everything... but he's not calling it stealth.

Then use something else. Like exhaust nozzles cooled by the fuel itself (something several models of real spacecraft engines already do--the goal isn't stealth, it's usually to preheat the fuel, but this idea can be adapted for stealth in space).

The exhaust is still is a problem, and you need your ship to be cooled to nearly absolute zero.

Room temperature is still to hot to hide.

Which means a 10-30% reduction in the infrared signature.

Whoopedy do... and now since your ship mass has increased from spamming thermocouples all over it, you are more massive and need more thrust, probably a higher Isp engine.. and now you have more power output, and more aste heat to capture.

Wrong. At half the temperature the effective detection range gets cut in half. Any heat source becomes too dim to spot at a certain distance,

Wrong....

#1) at half the energy output, effective detection range is cut by 1/root(2), due to the R^2 law. At half the distance, the signal is 4x as intense.

Given that the detection ranges are in dozens of AU, reducing your thermal emissions by half is only going to lower your detection range by ~70%... which is still measured in astronomical units so high, that even my wet dream(will that be censored?) exotic FEL laser systems won't be in range when you are detected. You'll still get detected long long long before you are in range for a fight.

#2 - there is no way you're going to lower you exhaust's thermal emissions by a factor of 2 just by having some part of your ship obscure it for the tiniest fraction of a second as it exits the nozzle. Know what elese obscures exhuast? a nozzle. You're essentially claiming a longer nozzle will hide the exhaust. The exhaust won't cool by conduction... but by thermal radiation, and that won't decrease significantly in 1 ship length. The exhaust may cool slightly by adiabatic expansion... but when it leaves the nozzle, its already expanded a lot relative to the throat of the nozzle... its nearly as cool as its going to get... a longer nozzle won't help.

if you play KSP, you know how big a deal "heavy" is!)

Like all that fuel for a low Isp engine because you want cooler exhaust? like plating your ship in thermocouples to get your 50 AU detection range down to 40 AU? (assuming that would even work)

You have no idea what kind of engines, at what power levels, we're actually going to see in space. That's one of the things we can only guess at.

Ok, you build a space warship/missile in KSP using sepratrons for propulsion, and I'll build one using LV-Ns... we'll see how that goes.

We know that particle speed correlates with temperature -> physics

We know that Isp correlates with the particle speed of the exhuast -> physics

We know that you're going to need high Isps to get anything reusable (like a warship) and not expendable (like a missile).

Even something expendable, will need ridiculous dV to get past even a UV laser defense system that operates at more "reasonable" ranges of only tens of thousands of kilometers

Hell, even the A-10 Thunderbolt's extremely cheesy method of masking its infrared signature (rear control surfaces surrounding the engines to the sides and below) makes it very difficult for a defender on the ground to get an infrared missile lock. That trick will certainly work in space

Won't work at all. You need to be colder, and there's no air to mix with the exhuast to cool it.... see above #2.

And here's another trick: four engines, each at one-quarter the power. Thereby splitting up the one heat source into four smaller ones.....

And the total thermal energy output is the same, and at when you are 5 AU out, they can't even resolve the difference between 1 vs 4 engines. You are detected just the same.

.....if the ship is close enough to a sensor for whatever temperature the exhaust is.....and if the sensor is looking in the right direction. There's the "perfect recon" fallacy again. Can't rely on that.

Yea, ok, so if I have 1 guy looking around, looking out, at night, and you try to sneak up on him in a bright glow in the dark suit, we should think you can do it, because to say you can't do it is a perfect recon fallacy.

You are observable at dozens of AU.... that is plenty of time to obtain sufficient recon.

You are also rely on a perfect recon fallacy in the first place to assume that you can evade enemy recon, by assuming you know exactly what directions you should not radiate.

Something that is an observatory, and only an observatory, that does not participate in combat in any way will still be visible due to solar radiation and being heated above the CBR, but it will see your warship long long before you see it.

-although something orbiting out at the kuiper belt, not making any maneuvers, with a power output barely sufficient to work its IR camera... would be pretty stealthy... but thats the only way to be stealthy... sit still, don't do anything, far from a star/energy source.

And you can't switch between active and powered down states.. because to become "stealthy" like that, you follow the same path you were on before you became stealthy... when you were visible for dozens and dozens of AU away, and everyone knows where you are and where you are going, and can still go intercept you and destroy you.

No it doesn't, that would break the laws of thermodynamics. Thermocouples generate a current from the transfer of heat down a gradient, you still get the heat transfer.

To be fair, he did say less heat... but as I mention above, that doesn't help much.

Sure, you capture some of the thermal energy and store it in another form instead of radiating it... you're still seen easily by what you didn't capture.

Given that, the appetite for exotic X-Ray FEL lasers measuring kms in length, I think, will be small to nonexistant, for a long time. Such size of weapon almost counts as a fixed installation by default, and fixed installations are kinetic fodder.

Well, its hard to say... If you are mining and manufacturing in space (16 psyche maybe?), there is really no practical limit to how large you can make your spacecraft. Its also how hard to say how much these things can be compacted. How small will a fusion reactor ultimately be?

How cold can you keep your magnets for the FEL, and how much will high temperature superconductors be advanced? What sort of power densities can you pump through your FEL? I don't know.

Even an instalation... such an installation should be able to swat incoming kinetics away with ease, I don't see why its kinetic fodder.

If your enemies base of operations is within range, they can't even launch to orbit without being swatted away, let alone launch kinetic at you.

If such an installation were orbiting in the asteroid belt right now... there's nothing Earth could ever do do stop it... we'd never get anything to orbit, and we can't get a similar installation in firing position to take it out because of the atmosphere.

[GeneralVeers]

No it doesn't, that would break the laws of thermodynamics. Thermocouples generate a current from the transfer of heat down a gradient, you still get the heat transfer.

I understand the laws of thermodynamics fine. What they say is, you don't get something for nothing. A thermocouple (or a solar panel or anything else) can't simply pluck free energy out of thin space. (snicker)

Describe for me a potential rocket engine design that has ISP above 100 and does not involve a massive thermal signature.

A cylinder of gas stored at very high pressure and low temperature. To use the engine, you don't ignite the gas; you simply open the valve. Know what happens to gas under pressure when the pressure is released? It cools very quickly. The ISP of the system would depend mostly on the storage pressure. There you have it: thrust without a significant infrared signature. The problem being that it produces less thrust per unit mass of propellant. No, I have no idea how much gas at what pressure would produce how much ISP, but the basic concept is definitely workable. In fact, I think that's how a lot of real RCS thrusters actually work: by simply spraying compressed gas instead of actually igniting anything.

Possible downside: if the exhaust gas liquifies or forms crystals, the liquid/solid form might produce a detectable radar signature......

Directional antennas are a lot easier to make than directional heat radiation.

And carry the inherent risk of slipping off-target. Oh, and directionals are still possible to jam, because you don't have to jam at the source--it's what the receiver hears that matters.

And there's another problem I didn't think of before. The sentry satellites themselves are very hard to spot, of course--but how do you get them there without the launchers (or the final-positioning RCS burn) being spotted? That's the problem. Getting a strong survey network in place to prevent stealth, requires stealth. And if there's no stealth in space, as people keep claiming......then the Other Side will know where all of the probes are, and will try to shoot them down, so you'll have to defend or replace them, and once again the battlefield devolves into the same cat-and-mouse games that are already played on real battlefields.

Okay, maybe I misspoke. Not terawatt... Whats the next bigger prefix? Petawatts... Yeah, that might do.

Did you mean the next lower prefix? Gigawatts? That might be workable--a ship the size and mass of a thousand Boeing 747's is a lot, but probably we could put that in orbit with present-day technology. However, that would be a ship armed with a single laser. Whereas the missiles needed to punch a lethal hole in such a ship could be mounted on a drone the size of your car. That's the tradeoff with a laser: more hardware and mass for less damage output, but with better accuracy and basically unlimited ammunition.

Yes, I'm aware of YAL-1, and it's a toy compared to what you'd need in interplanetary conflicts at distances of millions of kilometers.

Depends on the combat role. For point defense against missiles and unguided shells, the YAL-1 would probably work fine. Longer laser exposure would be needed to destroy a target, though (the way modern lasers usually destroy planes and missiles is by damaging the target's hull so it suffers aerodynamic failure and either tumbles out of control or breaks up--which won't happen in space).

How big are the sensors needed to spot a shuttle RCS plume at the distance of Mars? Are we talking a liquid helium cooled infrared telescope, or a (large) solid state CCD like what FLIR uses in their cameras?

Other important question: what's the viewfield angle at which a shuttle RCS plume can be spotted? Wider view = lower resolution.

Sensor warfare isn't the same thing as stealth.

It's an integral part of the game. Stealth in space is all about numbers: "am I generating enough heat to be detected, and at what range". Fewer operational scanners means less chance of detection.

The exhaust is still is a problem, and you need your ship to be cooled to nearly absolute zero.

To be invisible at what range? For example, the FLIR sensor Lord Aurelius mentioned a few posts ago? How close would that FLIR sensor have to be to detect a target two meters by two meters whose surface temperature is a hundred degrees Kelvin?

You have no idea. Yes, anything above absolute zero is visible--if the sensor is close enough and has high enough resolution. You simply left out far too much stuff for your arguments to warrant consideration (that's why I skipped your other stuff, if you're wondering).

[SomeGuy12]

A cylinder of gas stored at very high pressure and low temperature. To use the engine, you don't ignite the gas; you simply open the valve. Know what happens to gas under pressure when the pressure is released? It cools very quickly. The ISP of the system would depend mostly on the storage pressure. There you have it: thrust without a significant infrared signature. The problem being that it produces less thrust per unit mass of propellant. No, I have no idea how much gas at what pressure would produce how much ISP, but the basic concept is definitely workable. In fact, I think that's how a lot of real RCS thrusters actually work: by simply spraying compressed gas instead of actually igniting anything.

.

Keep going. Go through the exercise. What's the fastest gas you can use? If you permit it to expand, how fast will it leave the cylinder? How hot does the gas have to be?

I know the answers, but I know you won't believe me unless you do the exercise yourself.

[Rune]

I'm saying that at interplanetary distances beam weapons (using technology we have now or in near future) are not feasible. There are too many issues for them to be an effective weapon that can be deployed on a spaceship.

1000m radius antenna? Come on. How do you turn that thing without it wobbling horribly out of shape?

Even if you could get a focused beam, pointing it accurately at a few million kilometers is going to be hard.

I concur, but infeasible interplanetary lasers doesn't mean that lasers don't get stupendous ranges for ship-to-ship combat.

I'm a little confused.

1. Are you saying you can't focus, with a big mirror on the order of 100 to 1000 meters radius, onto a target at a great distance using UV or X-rays?

2. Are you saying you actually need that kind of beam power if you can get a small, tight beam at whatever distance you are at?

The whole idea is that if you are using a laser against an enemy vehicle in the same weight class, the enemy can shed just as much heat as you are sending. So you have to be able to focus the beam onto a small enough area to vaporize a hole in their systems. The vapor gets lost to space and so the enemy ship loses mass, and the functionality of whatever system the beam burned through. Burn a hole in the enemy power source or the enemy weapons or the enemy radiator junctions and you win.

If you are forced to spread the light over their whole hull, you don't win. They can shed as much heat as you are sending, because by definition they have radiators about the same size, and your lasers are less than 50% efficient. (they basically have to be, because of that dreaded law of physics, entropy. An in phase laser beam focused in a single direction has very low entropy compared to the chaotic sea of high energy particles resulting from a fission, fusion, or antimatter reaction that is your power generator. So you have to shed the difference as high entropy heat)

Your "petawatts of power" idea only works if the enemy is massively out-massed.

That would be true... except sensors are much less resistant than hulls, and will be destroyed at extreme ranges with wide unfocused beams. Then it's not a matter of giving him heat that he can't shed, it's that once he is blind, he can't hit you and you can close in with impunity.

While such observations are certainly possible, I still think you are ignoring the severity of the problem. You still need sensors that can detect objects that merely have to contain a laser, a power supply, and some sort of heat-sink (presumably a liquid and vacuum chamber that can keep flooding the chamber so you can mask the IR until the laser has fired). Expect this to be few meters in a sea of millions of km. About the only real advantage you have is seeing that IR signature pop out against a 3K background, but you still need either outrageous resolution (or more likely sensors *everywhere*). Hubble can resolve about 25km on Mars (and I would assume this means pictures taken in 2003 with the 56 million km distance), this won't help at all with a stealthy ship. Not only that, but you effectively have to get near-meter resolution *in*all*directions*all*the*time*. No mere 2-d sweep with detectional RADAR, expect sensor ships *everywhere*.

That's quite wrong, actually. Resolving a target is not dependant on its cross section at all, it's dependant on their photon emission, and how many of those your sensor intercepts. Otherwise, there would be no freaking way you could see stars with the naked eye, when you can't see the moons of Mars, for example. I'm pretty sure if you work out the numbers Phobos would have a much greater angular cross-section than, say, Vega or Altair. See where I'm going?

So your detection range is dependant on power output only, and power output is dependant on your mass, isp, TWR, and firepower. And it's usually a couple (or ten) orders of magnitude higher than the 3K background, as you say.

Rune. Quick post because I have to go to bed. See u guys tomorrow!

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Keep going. Go through the exercise. What's the fastest gas you can use? If you permit it to expand, how fast will it leave the cylinder? How hot does the gas have to be?

I know the answers, but I know you won't believe me unless you do the exercise yourself.

"It's a trap!" - Admiral Ackbar. xD

[SomeGuy12]

Rune : we discussed this. So you blind a few sensors. How many more does the enemy spacecraft have? No, you can't close with impunity. They can either devise laser light shielded sensors, sacrifice a sensor periodically to get targetting information on you, get the data relayed from other observers you aren't lasing, use your laser beam itself as a target and a sensor that has enough attenuation layers to analyze the light from it, etc etc etc. Or set a nuke off as an illumination flare and use shielded sensors. Heh.

I think the only way to take a spaceship out of a fight is to destroy a system needed to fight in a way that cannot be quickly repaired. So burn a hole through their reactor, all their radiator wing-roots, etc.

And yeah, it's a trap. To be invisible to infrared, Wedge has to use a gas with the same temperature as CBR. The way we'd spot his proposed stealth space battlewagons is when they blot out the sun from their enormous propellant tanks. It's also a trap in that using cold gas like that makes you colder than CBR...which is also spottable as a cold spot against the background. Whoops.

Edited September 30, 2015 by SomeGuy12

[wumpus]

"just burn a few sensors"

To be able to consistently detect [small] IR signatures, you are going to need *lots* of sensors *everywhere*. Burning the ones near you just give away your position (but may allow you to take an unknown course. Doubtful, now that other sensors are pointing their long range sensors in your direction). Burning the ones near a target just means they dump more out to detect you (the ones out deep are irreplaceable, but vastly harder to get them all then mere stealth spacecraft.

Remember: space is big. You don't get sub km coverage over billions of km by just "a few sensors".

[Kryten]

That's also assuming a craft is carrying all of it's own sensors. It could get data from nearby planets, or satellites around them, or deploy sensor drones. A drone deployed with cold gas and with no active systems other than a directional radio would be as close to invisible as you're going to get.

[Kibble]

You guys should research the way we detect near-Earth objects. A hostile spacecraft and a minor planet have alot of things in common - they are small, shine dimly in the infrared spectrum, not actively communicating with you, and on unpredictable planet-crossing orbits. We have discovered hundreds of these over the years, but observatories on Earth's surface are pretty limited. If you wanna detect enemy probes with more regularity, you need dedicated infrared space observatories. But those have limitations too, like, limited mirror diameter, and you can't look anywhere near the Sun without dim stars getting completely drowned out (you know, the same way you can't see stars during the day), not to mention blowing thru your precious coolant.

Observatories on interplanetary orbits will be nessecary too, if you are fighting somebody inferior (as in, on an orbit closer to the Sun) to you. Like, Venus would have a huge advantage fighting Earth, because transfers would only be visible for very short times - maximum elongation! Unless Earth had some space telescopes inferior to Venus.

[KerikBalm]

There's no point arguing with Wedge...

"You have no idea, so I'm not going to consider your arguments"

He has no idea, so its not worth arguing with him.

[shynung]

I'm putting forward the idea of passive-reactive sensors.

This is the kind of sensor that, rather than scanning the skies like a telescope or radar would, simply pops open and waits there. Rather than being made of one telescope or dish on a turret, this is made of hundreds of photocells (think cheap cellphone cameras) mounted on a spherical base in such a way that there is at least one or two photocells looking at any arbitrary direction, similar to an insect's compound eyes. While capable of passive object detection like a regular sensor, albeit limited in accuracy, its main purpose is to deliberately let it be shot at by anti-sensor lasers. This way, the sensors can acquire the hostile laser emitter's position, and feed the targeting data thus obtained to laser counter-battery systems elsewhere.

[p1t1o]

Head on over here for a ton of relevant information:

http://www.projectrho.com/public_html/rocket/spacewarintro.php

(Specifically, the strengths and weaknesses of lasers and attack/defence scenarios)

[Mazon Del]

Incidentally, something I feel I should point out for the discussion on Blinding sensors Rune. You have two ways that the opponent laser can mess with your sensors, either you are over saturating them with data (imagine a flash-light being shined into a camera, the camera is working but it can't show anything useful) or you have destroyed their sensing elements (it's actually physically broken). Both of these are actually in their own way fairly easy to get around. We'll start with the harder case, where components are being destroyed.

You have, generally speaking, two ways you can go about making this work. The first is that you just have a crapton of disposable sensors and you don't care that they are getting burned because they last long enough to be useful and are cheap to replace. On a spacecraft with mass restrictions, this option is less than ideal, but still workable. The second is that you increase the robustness of your sensor system in some fashion. Here's an example, you have a filtered pane of glass in front of your camera lens that blocks something like 90+% of the IR (or whatever) coming through, make it multispectrum blocking if you want. Then you just ensure that your active cooling systems (coolant flowing around inside your ship) are keeping that pane nice and cold (which you are likely doing anyway for the camera's thermal stabilization). What this means is that you can have a terribly sensitive camera that is protected from the attacking energy as most of the IR is getting soaked up by the pane which is ideally cooling enough to minimize (though of course not actually stop) vaporization/drilling. What would this sensor see? Most of the time probably nothing except for the sun, nearby planets, very nearby drive plumes, possibly (but unlikely) a few stars, and any time someone fires an IR beam at the ship/camera, they'll show up like a nice bright spot. What was it you were trying to do with this camera? Find a bright spot of IR that is your enemy so you can target them? Sweet deal! Free beacon targeting!

Now, in the case of your sensors being blinded, this is just a matter of crafting your sensor correctly. An example would be a camera with a fish-eye lens. If you shine a blinding light at it, the system has enough data it can pick up from other directions (where your oppressively blinding light is not shining from) that now the centroid of the light blob can be determined, what's at the centroid of this blob? Why the ship causing the blob! Free beacon targeting!

Modern day ECM/ECCM is WAY beyond "I'll just spam out noise that they can't penetrate.". Sure, that works on some of the lower tech countries, but for people like US vs Russia the game gets very interesting. We've worked on the problem enough that "noise spamming" a tactic that you intentionally do to get the enemy to shoot at whatever is causing the noise spam instead of something more important. But then when people started doing that (like dropping the spammers on missiles/drones), we also figured out a variety of ways (doing things I mentioned above pretty much) to look past/through the spamming to find out what we want. These days the game is more about trying to confuse the radar returns to make it look like the plane is either something that it is not, or to make the radar think the plane is somewhere it isn't. That's the thing though, ECM/ECCM warfare really only gets that chess-gamey on radars and such because the enemy DOESN'T have a radio beacon announcing where it is in the middle of a firefight (IFF is different, shush). That's what the IR signature of engines or your ship is, a beacon announcing to everybody where you are at all times. There is not a lot you can do to play ECM games with that. You can pump out a blob of hot gas now and then and that might draw their targeting off to the side, but that is a losing game on your part.

[wumpus]

You can pump out a blob of hot gas now and then and that might draw their targeting off to the side, but that is a losing game on your part.

Is it? This seems to assume that "battlespaceships" (spacecraft with weapons) will have to do more than orient their weapons on a target. If the assumption is if moving gives you away and allows the enemy to destroy you with a beam weapon, then DON'T MOVE. Just fire your beam weapon from wherever you are. You might have a ton of decoy "ships" pretending to acquire targets, but at interplanetary ranges the ship will have fired before you see it move (due to speed of light issues). I'm assuming that not only is there no way to tell an asteroid from a ship (pretty trivial), but also that spacefaring societies can launch such ships without (ussually, but just not always will work) having them detected. Presumably manufactured inside an asteroid or something (presumably anything moving from an oort-based orbit to the asteroid belt will get carefully checked with "active RADAR" to determine just what it is supposed to be, if simply blown up by any side aware it isn't theirs).

Once one side decides to start a war*, all known targets are attacked with all weapons believed to be compromised plus enough additional sacrificial weapons needed to destroy all known targets. Once this attack is detected, surviving weapons and enough sacrificial weapons are used to destroy the now known weapons (note, if the weapons are dispersed much beyond the orbit of a planet (or moon), they won't be able to coordinate strikes but more or less attack by predetermined zones of responsibility). This cycle continues until one or both sides die or surrender (asking for a draw within minutes of a holocaust seems outside of human psychology).

Expect losers to send a gotterdammerung message to remaining undetected (possibly occluded from the battle) weapon ships to hold fire for maximum damage (the net effect would be something like dealing with land mines long after a war). The more obvious gotterdammerung weapon would be waiting in the Oort cloud, ready to divert comets (preferably iron stuff, but will use a snowball if has the right orbit) at targets.

* if things favor the first striker as much as it looks like here, expect a very unstable situation with a war happening well before all ~10^30 km^3 of interplanetary space can be sensed at sub-km scale. Then again, this means most "spacebattleships" won't be detected.

[Mazon Del]

Moving is not what gives you away exactly. It's that you are a warm entity compared with most of the observable universe. Moving just tends to mean you've used some sort of engine or device, which is going to make you even hotter and thus more noticeable. If you have a human crew aboard your ships, it is going to pump out enough heat that there is no way to actually hide it. Even for automated vessels there is going to be some heat release. Pretty much by the time that we have the sort of industry to devote to secret factories producing secret ships, unless man has been at peace for hundreds of years and thus no longer distrustful of each other, we are going to have a system in place (probably multiple, from all sides) watching just about every warm chunk of object this side of the oort cloud.

Though space does somewhat guarantee that at least you have the opportunity for a second strike. There's just too much space and not enough ability for sneaking to actually have a total kill first strike.

[GeneralVeers]

There's no point arguing with Wedge...

"You have no idea, so I'm not going to consider your arguments"

He has no idea, so its not worth arguing with him.

You're half right. There's no point arguing with me--just not for that reason.

You can spew theories at me until your keyboard breaks, and I won't care because the brightest minds in the world have been wrong many, many times. To prove an argument true or false, you have to test it. And this thread is almost entirely about stuff we can't test. So don't go saying "that guy's wrong" when you've got no way to prove it.

Is stealth in space possible? Yes. Will it be worth the effort? No way to know until Space War One breaks out (except that it won't be called "Space War One" until after the second Space War breaks out). Humans will definitely attempt stealth in space, because whoever does manage to make it work will have a gigantic advantage in a space war.

[wumpus]

Moving is not what gives you away exactly. It's that you are a warm entity compared with most of the observable universe. Moving just tends to mean you've used some sort of engine or device, which is going to make you even hotter and thus more noticeable. If you have a human crew aboard your ships, it is going to pump out enough heat that there is no way to actually hide it. Even for automated vessels there is going to be some heat release. Pretty much by the time that we have the sort of industry to devote to secret factories producing secret ships, unless man has been at peace for hundreds of years and thus no longer distrustful of each other, we are going to have a system in place (probably multiple, from all sides) watching just about every warm chunk of object this side of the oort cloud.

Though space does somewhat guarantee that at least you have the opportunity for a second strike. There's just too much space and not enough ability for sneaking to actually have a total kill first strike.

I've always assumed that any stealth battlespaceship would be unmanned (making cyberwarefare that much more dangerous), and would have little more than a radio receiver active while dormant (thus the need to rotate and acquire the target once activated). Hiding them during/after launch seems next to impossible, hiding crew changes just makes it worse. Radio (recievers) barely take any power: anything capable of radiating away ship-killing laser blasts can dissipate the IR trace down to next to nothing. Making the laser, power supply for laser, attitude control, radio, any navigation abilities (not to likely) all work at 3K is probably a much harder problem (although by this point space engineering is almost certainly common enough to solve this with easily available off the shelf parts).

I'd assume that the reason you don't have a total kill first strike is that you can't find all the ships sneaking around (especially outside the elliptic). I'd expect the amount detected to be pretty small. My guess is that you have to detect them as they launch. You can sneak all you like as long as you stay in one orbit.

[RainDreamer]

If it is transmitting/receiving any kind of signals, it can still be traced. It should be completely autonomous. Which means advanced AI. Which can also means some terrifying possibilities.

[NuclearNut]

I am sorry if I do not understand this matter, but what is the point of conducting war with spaceships? From what I understand the only things worthy of colonization and thus strategic control are planets and asteroids, said asteroids and planets also have a massive advantage over nearby spaceships due to their massive capacity for heat, thus allowing truly massive lasers to be added. Oh, and they do not need to be shipped around on huge cost and can have batteries located behind hundreds of meters of rock and hidden from view.

Now look at spaceships, to make a spaceship travel to a nearby star system or even planet requires a phenomenal amount of delta v, and the fuel in this case would equal the cost of a new spaceship, thus it would be best to simply make the ship go on a one way trip to the target, unload a large number of nuclear warheads with or without a cobalt jacket, or if fast enough simply impact the target. Once that is done re-colonization would be quite possible and practical.

I see, in a war where the cost of a missile is cheaper than the cost of a spaceship going there dropping bombs and returning, a lack of reason for spaceships or space based combat, rather I see a need for bypassing enemy defensive systems through internal action and large swarms of missiles heading from planet to planet, star system to star system, with the goal of removing individual targets.

[GeneralVeers]

I've always assumed that any stealth battlespaceship would be unmanned

Very likely. Humans have a pretty significant infrared signature. An unmanned ship could run a lot colder and would be that much harder to spot.

Making the laser, power supply for laser, attitude control, radio, any navigation abilities (not to likely) all work at 3K is probably a much harder problem

This could be done if the ship ran on battery power instead of a reactor or radiothermal generator--the tradeoff being limited running time. Making a computer run cold? Definitely possible, seeing as how miniaturization technology is aimed at doing more with tinier circuits running at lower power levels. Instead of that CPU in your gaming PC that generates so much heat it would melt if you took the heatsink off, a computer with less dense circuitry would run significantly slower......but also significantly colder.

Keep going. Go through the exercise. What's the fastest gas you can use? If you permit it to expand, how fast will it leave the cylinder? How hot does the gas have to be?

Irrelevant. Though you definitely want an inert gas that won't react with the interior of the container..... What's important with a cold-gas thruster is how high you can get the pressure in the storage vessel; that's what determines the exhaust velocity and the burn time. (lol--"burn" time)

In fact, why should I obey your requirement that the engine produce at least 100 ISP? I say that's irrelevant too. The ISP of a cold-gas thruster would certainly be pretty low, but if it's enough to, say, dock with a space station without producing a heat signature, it would still be useful.

[0111narwhalz]

How about a Dyson swarm (not shell), configured with reflective solar sails? When you want to kill something, point the sails such that the beams focus roughly at what you want to kill briefly. Tell each swarmling to do so at a slightly different time and angle, so that it saturates the region of the target. A similar concept to the Nicoll-Dyson Beam, but with a different application. When something wants to kill you, you don't care; the swarmlings are independent of one another and are cheap enough to throw up in the dozens.

Before you tell me that solar sails are not enough to keep an object in "orbit," let us consider a particular orbit. One which is eccentric by the exact quantity supplied by the sails.

As to stealth, what are you going to point your telescope at? Sol? That's a surefire way to blind your sensors. The scope is plated with smoked glass or something? The swarmlings are small enough, and plentiful enough, that you're not likely to get any meaningful data. The swarmlings are also free to use hot engines, because their backdrop is the single brightest object in the sky, itself powered by fusion. How are you going to spot a fusion plume against a fusion ball?

[KerikBalm]

You're half right. There's no point arguing with me--just not for that reason.

I think this is a good quote: "the brightest minds in the world have been wrong many"

They have been wrong, and you most certainly are in this case.

That is actually the reason

You can spew theories at me until your keyboard breaks, and I won't care because the brightest minds in the world have been wrong many, many times.

So... you won't listen to any logic or reason... because other people have been wrong... that's great logic...

To prove an argument true or false, you have to test it.

So you will continue to insist that you are right, untill we have a deep history of space warfare.... got it.

Is stealth in space possible? Yes.

Oh look, a statement supported by neither testing nor logic and reason.

Given we can already test detection in space, there is certainly more evidence for the no stealth in space argument.

In the absensce of any evidence supporting your view, or any reason supporting your view, you continue to insist that you are right.

You don't even give points that can be debated.

You simply call yourself right and the otherside ignorant.

[SomeGuy12]

Wedge, I agree with Kerik. Taking the position that "because we can't test X, my position Y is correct" is a fallacy. Even though we can't test X, from what we know now, stealth in space is not possible. You can only make reasoned opinions based on current knowledge. Maybe FTL travel is possible or you can escape to parallel dimensions to sneak up on a target, or maybe there's a way to have total omniscience about an area of space. You can't make a reasoned judgement on "maybes". When we say "there's no stealth in space", what we are saying is, "based on the best current knowledge of physics and thermodynamics and compact sensors, stealth in space is extremely unlikely".

We don't care what your speculation about future knowledge is. If you have a meaningful opinion to give based on current scientific knowledge, I'd be glad to hear it, but speculating advances that are not currently known to be physically possible is a waste of time and space in this thread.

[cypher_00]

What if instead of trying to go stealth by cooling things down you do it the other way around by deploying a swarm of thermal decoys that blind the enemy's sensors?