Footfall vs RL

[Junghalli]

You could, and while that means they won't know where you're coming from, they will still know that someone is there who doesn't want to be seen. So you may just end up making it harder for you to hide.

Yeah, but if you could make convincing decoys then you could send them in different directions and confuse the enemy as to which one is your actual ship, which could be useful in all sort of possible ways.

Destructionator XIII observed on another board just now that people tend to think of stealth in terms of hiding, but it doesn't necessarily need to be that. It just needs to be able to compromise an enemy's situational awareness.

[Stark]

Even having difficulty correctly establishing the orientation, position or heading of objects is useful; there's a huge scope between magic ST sensors that can read the size of your shoe from across the system and 'blind as a bat'.

[Gil Hamilton]

Couldn't you also hide your relatively cool ship by having warmer decoys drawing attention away from you?

Depends on the body you are hiding against. A warmer decoy doesn't make you more stealthy, because people can necessarily detect the decoy if they can detect anything at all. Hiding against a natural body that has a similar temperature as you might help as along as it is much much bigger or hiding against something that is screaming IR (like say, a star) as well. In that case, you can be lost in the noise of the detector. Of course, most natural bodies in space aren't known for being very warm, so they aren't very good blackbody radiators.

The best way to not be detected, of course, is be far enough away. You need arrays of telescopes working in concert to achieve good resolution over interplanetary distances, due to limits in how good it is physically possible to make a telescope and detector. If you are trying to approach something undetected, the truth is you are going to have to resign yourself to the fact that eventually they are going to notice you if you intend to stop while there. I imagine you can do tricks as you are approaching, like covering your vessel with tubes of high heat capacity fluid that you can quietly sweat off to mask your heat, but at there isn't much I can imagine you can do about your drive once you turn it on.

[Simon_Jester]

Guns, missiles, interceptors, lasers. Fighters would be in a completely different environment than the interplanetary (ish) situation described a few posts ago - they make the most sense in a tight, crowded setting, something like a space orbital habitat cluster, where there's a billion people within a few hundred miles.

Since all your threats are close in and there's metric assloads of cross-habitat space traffic, watching everything is a pain and there's no need to build huge telescopes to begin with. All trips are fast and there's no need for engine burns at all for a great many trips. (The rotation of the habitats means you are already in motion.)

You're also in the middle of active sensor systems- it's like trying to hide in an air traffic control environment by flying a cargo plane and pretending to be a civilian. You can do it, but you might as well just fire missiles as far as I can tell.

You also has a problem if the enemy's got competent traffic control and starts double-checking; you're close enough that it won't be all that hard to focus a camera on you.

Congratulations, you just shot down a civilian transport! It was inertial to conserve fuel; keeps costs down with passengers who don't mind waiting.

Don't be wilfully obtuse. A civilian passenger would damn well answer hailing signals, or damn well look like a civilian transport when someone fires a probe past it at a few thousand kilometers on a flyby. It would also be a good idea to have a transponder, things like that, precisely so civilian traffic isn't mistaken for a warship.

Of course in theory, your stealth ship could be disguised as a civilian vessel... but at that point you're not really protecting the ship with stealth; you're protecting it by disguising it as something else entirely. A civilian ship would not want to be invisible to people on the receiving end, for a number of reasons.

Beats a lethal dose of X-rays, no?

Maybe. But are your crews going to stay alert after a few false alarms? Machines maybe. Humans, that's not so easy.

1) What makes you think I haven't got computers on the fire controls?

2) It's not like this is particularly demanding duty. All I need to do is have people ready to man their battlestations while probes check out the

3) I would think that when there is supposed to be a war on, yes people would be willing to spend long periods of time being bored on duty. That's half the point of military organizations: to force people to do boring and unpleasant things for long periods of time. (The other is to force people to do exciting and unpleasant things for short periods of time).

Moreover, if you're counting on this strategy, then you've got a plan that only works if the enemy is stupid or not paying attention, on a strategic level, in an environment where mistakes mean mass destruction. That's like counting on the operators in an ICBM silo being asleep at the switch when the Big One gets dropped.

Does it matter? I can get the fine details of where your ballistic stealth ship is headed by launching a space probe to do a flyby mission past it and ping it with lidar from a few thousand kilometers.

For everything I launch? Everything my neighbors launch?

For everything you launch that can't be verified to be civilian shipping? Why not? We're talking about things way cheaper than a large starship.

The probes are only an emergency response in the case of something that's not responding to hailing signals (it can't for fear of being localized), that can't be confirmed to be non-hostile. Any prudent nation would already have plenty of the things in stock for routine purposes, because there are a lot of reasons to want to do a flyby to check out things that might be of interest.

And what if there's hundreds of countries out there, like in the real world. Are you watching them all like that? What if I decided to slip in via Canada rather than the direct approach? Are you watching them in such detail too?

...Uh, are we talking over interplanetary distances here? Clusters of habitats separated by interplanetary distances?

This isn't like borders on the surface of the Earth; you have to start from a well defined point that will be visible to the person you're launching at.

In a more cluttered environment you could conceivably conceal a launch... as long as no neutral parties tip your target off: "Hey, habitat 827, habitat 129 just launched something ballistic in your direction, want us to check it out?"

-The enemy has resupply from his own base, and may be able to afford the luxury of keeping a few weapon systems continuously ready to fire, or ready to fire on very short notice. Thus, you're trying to beat someone to the draw when their weapon is already in their hand.

My first wave will just have to be bigger than your alert forces.

...And highly mobile. And of course, they have to come close enough to beating the opponent to the draw; otherwise you lose a respectable fraction of your attack wave before opening fire.

If you have this kind of superiority over an inattentive, poorly equipped opponent, you don't really need anything else to win.

-The enemy may well spot you from so far out that they warm up their weapons far in advance- a major risk if they are clever and have mobile recon assets.

Yup. It's not a silver bullet. All I'm saying is a) it exists and b) it plays a role.

Bayonets play a role in modern warfare too- more as can openers than as weapons, though.

My argument here is that stealth is not a good way to get into a firing position before becoming a target for enemy return fire. Nor does it force an opponent to do anything particularly expensive that they weren't already doing. As such, its role is minimal.

[Guardsman Bass]

Couldn't you also hide your relatively cool ship by having warmer decoys drawing attention away from you?

Depends on the body you are hiding against. A warmer decoy doesn't make you more stealthy, because people can necessarily detect the decoy if they can detect anything at all. Hiding against a natural body that has a similar temperature as you might help as along as it is much much bigger or hiding against something that is screaming IR (like say, a star) as well. In that case, you can be lost in the noise of the detector. Of course, most natural bodies in space aren't known for being very warm, so they aren't very good blackbody radiators.

What about decoy emitter drones? At interplanetary distances the resolution is so poor that they all look like dots in terms of IR radiation, so you could have jettison a bunch of drones that fire up some really hot engines for a few seconds, and add to the total number of targets that the defense system has to track.

The best way to not be detected, of course, is be far enough away. You need arrays of telescopes working in concert to achieve good resolution over interplanetary distances, due to limits in how good it is physically possible to make a telescope and detector. If you are trying to approach something undetected, the truth is you are going to have to resign yourself to the fact that eventually they are going to notice you if you intend to stop while there. I imagine you can do tricks as you are approaching, like covering your vessel with tubes of high heat capacity fluid that you can quietly sweat off to mask your heat, but at there isn't much I can imagine you can do about your drive once you turn it on.

Pretty much. Somewhat realistic interplanetary combat seems to heavily favor defenders, who can have huge, immobile telescopes scanning a vast area of space, and then relay that data to the defending fleet for engagement and targeting.

The only real way to get around it would be superior numbers and waves of attacks. You'd probably have to send in a large first wave of drone ships that would get in close, actively scan the system with radar, and relay that information back to the second wave of ships and onward before getting destroyed.

I suppose you could also throw out distractions, like boosting asteroids into collision courses with planets, forcing the defending fleet to divert ships to deflect them.

Of course, if you also have a whole bunch of civilian ships fretting about, that complicates things.

[bz249]

Your imagination is really limited.

Guns, missiles, interceptors, lasers. Fighters would be in a completely different environment than the interplanetary (ish) situation described a few posts ago - they make the most sense in a tight, crowded setting, something like a space orbital habitat cluster, where there's a billion people within a few hundred miles.

Since all your threats are close in and there's metric assloads of cross-habitat space traffic, watching everything is a pain and there's no need to build huge telescopes to begin with. All trips are fast and there's no need for engine burns at all for a great many trips. (The rotation of the habitats means you are already in motion.)

Okay let's put some economy behind such a scenario, because military is not really hanging in thin air (except maybe Prussia an army masked as a state)... So I think it is a general rule, that the manufacturing plant represents more capital costs (read resources and labour, both things should be heavy limiting factor in case of a space habitat) than the product itself. So unless one produces quite an amount of a certain stuff it is cheaper to buy than to build. This is especially true for such economically inactive stuff like weapons. Of course national pride and other irrational things can play a role, but the most probable course would be that several space habitat team up together and produce weapons as a coalition/consortium since it can minimize the cost of producing one unit by reducing the spare capacity (waste of resources). So in that case any realistic war would be fought between alliances, so the stealth ships should foul each members sensors and better to take out each member or face retaliation.

On the other end of the spectrum, when weapon manufacturing is extremely cheap, so that each habitat can afford an own heavy weapon producing factory (so that can effectively kill another habitat) first strike could be an extremely tempting option to remove the threat of the potentially dangerous other habitats. To counter this each habitat should build up a second strike ability. Since weapon production is cheap enough, there is really no reason not to add another independent weapon drone somewhere far, the other option is to make mutual guarantee treaties with other habitats. Which again lead to a scenario where one has to hit multiple targets simultaneously to avoid the consequences.

[AniThyng]

Surely the main point about stealth , even imperfect stealth is the virtual attrition it causes by forcing the opposition to devote more care to ID and detection than he otherwise would need.

To use a modern analogy, why bother with camo for tanks when they show up like sore thumbs on IR sensors when running? Why bother using low observable paint schemes on non-stealth fighter jets when radar can spot them at will? (or stealth jets for that matter - if imperfect stealth = worthless, one wonders why the Silent Eagle or Super Hornet need exist at all)

[Gil Hamilton]

Pretty much. Somewhat realistic interplanetary combat seems to heavily favor defenders, who can have huge, immobile telescopes scanning a vast area of space, and then relay that data to the defending fleet for engagement and targeting.

Keep in mind the other factor, that the "huge array of telescopes" thing to provide good resolution through interferometry has weaknesses. You use it to get around the fact that any individual telescope is diffraction limited, but in exchange for higher resolution, you have greatly increased processing of an image and I believe noise as well. In addition, your Argus Eyes can only look at one thing at a time for a given array and the sky is vast. Remember, optical interferometry was first used and is continued to be used to look at stars and measure their diameter. I'm sure in the future they'll have better optics and processing power won't be an issue, but there are certain things that arrays of telescopes can't do physically. An object might get QUITE close to a planet and just happen to not be noticed if it isn't actively emitting radiation, and not necessarily tiny objects (though the smaller the object, the less likely it is to be detected).

The reason you have to resolve yourself to the fact that eventually someone on the planet you are approaching will notice you is eventually, your ship is going to become a strong emitter of radiation if you want to stop. Even then, it depends on the nature of the civilization on the planet. If the Message Bearer in Footfall headed for Earth today, there is a chance we'd never notice it until it blew up the International Space Station, let along when it turned on its drive to stop, simply because at any stretch of time we aren't watching more than a tiny fraction of the sky at a time. I'd like to think that someone would notice when they turned on their space drive and a new star moving impossibly fast across the sky appeared (once the thing is located and put under observation, it would be impossible to disguise the fact that it is under power), but like as not it might be an ameteur astronomer calling in an object he can't recognize to the local observatory as much as someone from NASA.

The only real way to get around it would be superior numbers and waves of attacks. You'd probably have to send in a large first wave of drone ships that would get in close, actively scan the system with radar, and relay that information back to the second wave of ships and onward before getting destroyed.

Maybe. Depends on how long you want the attack to take to get there. Large stationary objects in predictable orbits or on the surface can easily be destroy by a ceramic covered metal cannon ball which is extremely unlikely to be detected before it hits if the attacker is willing to wait six months for the cannon ball to get there.

Further, attacks have the advantage that they don't necessarily need to stop, while the defenders are by definition stationary. The attackers may put themselves in an orbit that intersects the planet they want to attack, but not choose to park, but instead make a fly by where they only release their weapons when they are at the closest approach. Orbit and repeat as necessary, or have it be in waves strung out like a string of pearls at irregular intervals. You can even just push your missiles into space so that all of them are out (inertia will keep them on target, as they are being "aimed" in advance by the ship) so that all your ordinance is already in space in advance, then only turn them on when they are close to something you want destroyed. The attacking ships need never get close.

Or something else, depending on the technology available. The point is that it isn't so cut and dry as you make it sound.

[Simon_Jester]

Surely the main point about stealth , even imperfect stealth is the virtual attrition it causes by forcing the opposition to devote more care to ID and detection than he otherwise would need.

To use a modern analogy, why bother with camo for tanks when they show up like sore thumbs on IR sensors when running? Why bother using low observable paint schemes on non-stealth fighter jets when radar can spot them at will? (or stealth jets for that matter - if imperfect stealth = worthless, one wonders why the Silent Eagle or Super Hornet need exist at all)

This is absolutely true. The problem comes when the marginal cost of adding more stealth exceeds the value of the stealth. If adding a low observable paint scheme to a fighter jet added three or four tons of weight, people normally wouldn't do it: the value of having those extra tons of weight to play with exceeds the advantage you get from painting your plane gray.

My argument is that against a competent opponent willing to spend pennies on detection per dollar you sink into stealth ships, the effectiveness of stealth is extremely small. This isn't the scale of virtual attrition Stuart talks about a lot, where adding extra countermeasures decreases the enemy's strike capability by a factor of two or something. It's more like it decreases their capability by a few percent, and you pay for that.

You pay in increased travel time, which means a greater risk of the ship having an engineering casualty en route and the mission failing.

You pay by having to launch your attack far ahead of time: if the enemy watched your ships launch and knows they're coming (via intel, long range and sensitive telescopes, or the like), he has much more time to prepare than he would against a simple brute-force attack that comes in faster: months instead of weeks or days.

You pay by having a highly all-or-nothing strategy: the stealth ship may be able to get into firing position if it is not seen, but if it is seen it will almost certainly be destroyed without being able to defend itself effectively, because its low closing speed gives the enemy plenty of time to engage with long range weapons (especially guided ones).

[bz249]

You pay in increased travel time, which means a greater risk of the ship having an engineering casualty en route and the mission failing.

You pay by having to launch your attack far ahead of time: if the enemy watched your ships launch and knows they're coming (via intel, long range and sensitive telescopes, or the like), he has much more time to prepare than he would against a simple brute-force attack that comes in faster: months instead of weeks or days.

Those are consequences of being interplanetary in the first place, with my conservative engine assumptions. It has nothing to do with stealth.

Playing in the orbital battleground, well one can destroy the enemy targets with powerful enough lightspeed (or near light speed) weapons without any notice. So the only need for a stealth ship arises to disguise who was behind the attack. However simple terrorism, or using neutral transports or any other methods are way better then active stealth.

You pay by having a highly all-or-nothing strategy: the stealth ship may be able to get into firing position if it is not seen, but if it is seen it will almost certainly be destroyed without being able to defend itself effectively, because its low closing speed gives the enemy plenty of time to engage with long range weapons (especially guided ones).

Why is it always that one side has perfect intel and the other side is a pack of one note idiots?

Well the possible approach vectors are known, the defending side can use active sensors (if the stealth ship shoots back they are pretty much defeated) they also have a way larger maneuver budget (and possibly more vessels also). So the only thing they need to know is someone approaching. That might not require an uberintelligence agency, indeed the opposite is true, the attacker needs a very good disguise and superb counterspy network to hide that they are preparing for something similar.

[Guardsman Bass]

Pretty much. Somewhat realistic interplanetary combat seems to heavily favor defenders, who can have huge, immobile telescopes scanning a vast area of space, and then relay that data to the defending fleet for engagement and targeting.

Keep in mind the other factor, that the "huge array of telescopes" thing to provide good resolution through interferometry has weaknesses. You use it to get around the fact that any individual telescope is diffraction limited, but in exchange for higher resolution, you have greatly increased processing of an image and I believe noise as well. In addition, your Argus Eyes can only look at one thing at a time for a given array and the sky is vast. Remember, optical interferometry was first used and is continued to be used to look at stars and measure their diameter. I'm sure in the future they'll have better optics and processing power won't be an issue, but there are certain things that arrays of telescopes can't do physically. An object might get QUITE close to a planet and just happen to not be noticed if it isn't actively emitting radiation, and not necessarily tiny objects (though the smaller the object, the less likely it is to be detected).

That's true, although I wasn't talking about interferometry. I was just stating that the defenders could probably afford to build up some truly gigantic stationary telescopes because they don't have to drag them around with them like an attacking fleet (although if they're launching attacks from a fixed position as well, that might not be the case).

The reason you have to resolve yourself to the fact that eventually someone on the planet you are approaching will notice you is eventually, your ship is going to become a strong emitter of radiation if you want to stop. Even then, it depends on the nature of the civilization on the planet. If the Message Bearer in Footfall headed for Earth today, there is a chance we'd never notice it until it blew up the International Space Station, let along when it turned on its drive to stop, simply because at any stretch of time we aren't watching more than a tiny fraction of the sky at a time. I'd like to think that someone would notice when they turned on their space drive and a new star moving impossibly fast across the sky appeared (once the thing is located and put under observation, it would be impossible to disguise the fact that it is under power), but like as not it might be an ameteur astronomer calling in an object he can't recognize to the local observatory as much as someone from NASA.

That's true. I was positing a scenario where the defender had an idea that something might be coming, and had defenses set up.

Further, attacks have the advantage that they don't necessarily need to stop, while the defenders are by definition stationary. The attackers may put themselves in an orbit that intersects the planet they want to attack, but not choose to park, but instead make a fly by where they only release their weapons when they are at the closest approach. Orbit and repeat as necessary, or have it be in waves strung out like a string of pearls at irregular intervals. You can even just push your missiles into space so that all of them are out (inertia will keep them on target, as they are being "aimed" in advance by the ship) so that all your ordinance is already in space in advance, then only turn them on when they are close to something you want destroyed. The attacking ships need never get close.

The defenders are not necessarily stationary around a planet, and I suspect the planet would mostly serve as a rally and supply point for them to strike out from. That was my point about the large stationary telescopes being an advantage for the defender - if they spot something, they can immediately communicate that information to defending spacecraft.

The attackers don't necessarily have that advantage. Sure, they could close in and launch projectiles at the planet itself (planets seemed to be screwed if the attacker is simply intent on completely wiping out an enemy), but they have an even worse problem with finding out where all the defending spacecraft are.

Of course, like I said earlier, this all depends on the defenders knowing that an attack might come, and being on their guard. If they're caught completely unaware, they'll probably lose if the attackers are just trying to cause as much damage as possible.

[Gil Hamilton]

That's true, although I wasn't talking about interferometry. I was just stating that the defenders could probably afford to build up some truly gigantic stationary telescopes because they don't have to drag them around with them like an attacking fleet (although if they're launching attacks from a fixed position as well, that might not be the case).

Man, can you imagine the maintainance you'd need on optical elements that size in space? Besides, those seem like big targets for metal cannon balls drifting in, since your telescope would necessarily be very large and be in predictable orbits. If any one of your mirrors gets damaged, your telescope is toast. No one sensible would construct such monsters, because its alot easier to use swarms of small telescopes and deal with the problems of interferometry than have to replace a kilometer wide parabolic mirror due to a random meteorite hit.

The defenders are not necessarily stationary around a planet, and I suspect the planet would mostly serve as a rally and supply point for them to strike out from. That was my point about the large stationary telescopes being an advantage for the defender - if they spot something, they can immediately communicate that information to defending spacecraft.

More of your guys chasing my guys means, less of your guys being present to defend your base.

The attackers don't necessarily have that advantage. Sure, they could close in and launch projectiles at the planet itself (planets seemed to be screwed if the attacker is simply intent on completely wiping out an enemy), but they have an even worse problem with finding out where all the defending spacecraft are.

And particularly those large optical telescopes you are counting to spot my fleet before I smash them. I don't need to destroy your fleet, I just need to make it clear that your fleet can't stop my fleet from smashing your base if I feel like it, so your guys had better surrender. I don't need to capture your pawns if I can checkmate your king.

Of course, like I said earlier, this all depends on the defenders knowing that an attack might come, and being on their guard. If they're caught completely unaware, they'll probably lose if the attackers are just trying to cause as much damage as possible.

Even with them being on guard, I think you are overstating the advantages of being a defender in this.

[Simon_Jester]

Man, can you imagine the maintainance you'd need on optical elements that size in space? Besides, those seem like big targets for metal cannon balls drifting in, since your telescope would necessarily be very large and be in predictable orbits. If any one of your mirrors gets damaged, your telescope is toast. No one sensible would construct such monsters, because its alot easier to use swarms of small telescopes and deal with the problems of interferometry than have to replace a kilometer wide parabolic mirror due to a random meteorite hit.

Yes, but the defender also has the advantage of being able to build and launch more telescopes, because they aren't hurling everything across interplanetary distances. It's best to assume the enemy does have a working deep space sensor net (umpty zillion Hubbles orbiting the planet and grabbing interferometer pictures of everything suspicious, while wide-field passive detectors serve to tip the Hubbles off as to where to look).

More of your guys chasing my guys means, less of your guys being present to defend your base.

Kind of meaningless, since we could equally well say:

More of your guys shot down by my guys means, less of your guys present to attack my base.

If the defender has parity in mobile units, their advantage in sensor and static-firepower capability will give them a big edge. If they're badly outnumbered in mobile units they may be screwed by lack of sufficient firepower to intercept everything that's thrown at them, but that's another matter.

And particularly those large optical telescopes you are counting to spot my fleet before I smash them. I don't need to destroy your fleet, I just need to make it clear that your fleet can't stop my fleet from smashing your base if I feel like it, so your guys had better surrender. I don't need to capture your pawns if I can checkmate your king.

It occurs to me that long range ballistic cannonball attacks are thwarted without too much difficulty so long as the opposition has even limited station-keeping capabilities. I don't have to make much of a course correction on the Giant Orbital Telescopes to dodge a ballistic weapon fired six months ago; I could be in quite a different orbit now than I was then, as a routine precaution.

At which point your pure-ballistic attacks are limited to targets that have zero maneuverability (planets and moons, not orbital installations), or to sporadic saturation bombing of the entire area around the planet (very difficult and energy-inefficient).

Range of any weapon in space is determined by how far shots can travel before the enemy gets out of the way; if the enemy has six months to dodge you're probably out of range. To make "cannonball" attacks work in this context you really, really need some kind of a guidance package.

[Connor MacLeod]

I don't have time to get too lengthy on this but, I have to ask the pro "No stealth in space" side a question: do you guys know for sure just how thoroughly the "Stealth" topic has been researched? And if so, where is the evidence? I dont know it very well so I have to question how thoroughly this has been investigated and backed up, because as I mentioned I dont trust it when people start stating things as certainty in sci fi analysis. And when I see alot about the capability and performance that is all well and good, but what about other aspects? Things like cost, maintenance (Gil I noticed brought these up - if others did I apologize for ignoring them) but other factors too. A big telescoep (for example) is going to be.. well.. big. How fast can you swing something like that around without compromising efficiency or damaging it? Does that mean that you need lots of big telescopes or can you get away with only a couple? How much money will these systems cost (both stationary and onboard ships), how much time and money and effort to maintain them, and what kind of economic situation is building them?

I want to point out that last one is a big question mark for me. I don't think we can just assume a sci fi society will magically have all the time and money and resources to just build whatever they need, even if we assume they have the inclination (Which is another pet peeve. Why do we assume "hard" sci fi humanity is so damn practical? RL humanity ain't nearly that smart most of the time.) Just having the ability does ont mean it is neccesarily fully or even intelligently applied.

And just to clarify what I think is becoming confused: those who are arguing AGAINST "no stealth in space" are ont arguing in favor of "stealth in space always works!" nor are they trying to say that many of the usual depictions of stealth (EG the "running silent" meme) are actually right. What those folk are arguing against is against the absolute NO STEALTH UNDER ANY CIRCUMSTANCES OR TO ANY DEGREE. Which is reasonable given that like with most sci fi concepts it probably hasn't been fully explored yet (there are on "space warfare" experts of this type we can refer to.) and there's alot more research to be done BEFORE an absolute is decided (if then.) It could very well be that stealth in space utlimately IS impossible, but it seems far too premature to just go declaring that it is, yet.

[Guardsman Bass]

I don't have time to get too lengthy on this but, I have to ask the pro "No stealth in space" side a question: do you guys know for sure just how thoroughly the "Stealth" topic has been researched? And if so, where is the evidence? I dont know it very well so I have to question how thoroughly this has been investigated and backed up, because as I mentioned I dont trust it when people start stating things as certainty in sci fi analysis. And when I see alot about the capability and performance that is all well and good, but what about other aspects? Things like cost, maintenance (Gil I noticed brought these up - if others did I apologize for ignoring them) but other factors too. A big telescoep (for example) is going to be.. well.. big. How fast can you swing something like that around without compromising efficiency or damaging it? Does that mean that you need lots of big telescopes or can you get away with only a couple? How much money will these systems cost (both stationary and onboard ships), how much time and money and effort to maintain them, and what kind of economic situation is building them?

I was just looking at some of the general ideas of how defense in space might be done without using any overt "magic-tech" solutions that violate the laws of physics as we know them (like FTL, planetary shields, arbitrary-resolution sensors, and so forth). Your civilization is obviously going to be limited by how extensive their space presence and space industrial capabilities are.

[Simon_Jester]

I for one freely agree there are things you can do in space to make yourself far more difficult to detect, when compared to a ship that does none of those things. Limiting production of waste heat is a good idea by default and will help. Not making engine burns in mid-course is quite normal and will help.

However, I do not think that some of D-XIII's schemes for using this kind of stealth to deliver devastating surprise attacks are as practical as he implies. Too many of them rely on the absence of what I would strongly expect to be relatively cheap countermeasures.

For instance, you don't really need high resolution to detect an infrared signature; you just need high resolution to resolve the physical dimensions of that signature and nail it down precisely. A highly sensitive passive IR detector does not need excellent resolution to tell you what general patch of sky contains an anomalous thing that is worth turning a battery of telescopes to look at.

High resolution optics are expensive and limited by their field of view, whether they're single big telescopes or interferometer arrays. High sensitivity optics are expensive too... but the costs are much less extreme than one might think.


Performance and cost are big issues, I agree with that too. But given that much of the equipment we're talking about already exists for satellite astronomy, and given the kind of improved hardware we'd need in order to be operating in space at this level, I'm inclined to doubt that it would be a critical show-stopper.


As far as I can tell, the best I've heard from D-XIII so far boils down to two options.

One idea is "disguise your armed ship as civilian traffic and achieve strategic surprise." Which I'd expect to work tolerably well, but it's not a 'stealth' tactic in the normal sense any more than an armed merchant cruiser is a 'stealth ship.' You're relying more on the enemy seeing you and mistaking you for something else than you are on the enemy not seeing you at all.

The other idea is "use ballistic projectiles, as opposed to ballistic ships." And I must say I like that. Ballistic solid projectiles are a viable option when attacking targets that can't dodge (even to the limited extent that they can shift their orbit slightly). Ballistic projectiles with terminal guidance are even better.

Very large ballistic projectiles with a time delay fuze might also be interesting, because they let you saturate cones of the enemy's space with small bits of hypervelocity shrapnel, if you time the detonation right and design the shell properly... but that's a personal hobbyhorse of mine.

Ballistic weapons, whose destructive power lies in their kinetic energy, can be a lot stealthier than ballistic ships, large platforms that themselves mount weapons to fire at an enemy. You can make them large while equipping them with negligible onboard power supplies, you can fire a lot more of them, and you don't have to worry much about casualties since you're writing them off the minute you fire them in any case.

[bz249]

Detecting a ballistic projectile is practically the same as detecting an incoming asteroid (well maybe finding the optimum adsorption coefficient and shape might help a bit). The smaller the projectile the more chance it will get through. I guess if humanity would ever able to wage space war then we would have a reasonably efficient asteroid collision warning system (since we plan to build such a thing nowadays... although we lack the resources and/or the really desperate willingness) under such conditions the only possible goal of stealth could be to reduce the heat/reflected light signature below of a detection limit of the asteroid detection system. The smaller the vehicle the easier to achieve this, but anything in with a cross section equal of a hundred meter sized asteroid is potentially hazardous which should be tracked nonetheless. So assuming that they have a much needed asteroid warning net only very small stuff can approach the target undetected (the Sun itself provides the required amount of illumination in the Inner Solar system).

[Junghalli]

Dumb weapons can't be ordered to stand down though.

You could put a remotely activated self-destruct charge in.

[Simon_Jester]

Detecting a ballistic projectile is practically the same as detecting an incoming asteroid (well maybe finding the optimum adsorption coefficient and shape might help a bit). The smaller the projectile the more chance it will get through. I guess if humanity would ever able to wage space war then we would have a reasonably efficient asteroid collision warning system...

The problem is that you really don't need something the size of an asteroid to be dangerous. The real menace from ballistic attacks is that the enemy will use small shots that travel much faster than asteroids (say, around 100 km/s), or small shots that travel at the same speed range (more like 10 km/s) but have terminal guidance that lets them home in on a target as they approach.

Either kind of threat would be much harder to spot than a hundred-meter asteroid, and yet either could carry enough kinetic energy to be very effective as a weapon against spacecraft.

a) Spy satellites. Slip them in to a relatively close orbit to keep an eye on people. Hiding them means they don't know what you have - and can't destroy them all so easily in battle. This might be one of the most useful things to have in practice.

Yes. That or reconnaissance probes on flyby missions, either way. In both cases, you only need stealth to last for a while; getting close enough to snap pictures is good enough for your purposes. And since the probes are expendable, relatively cheap, and above all small, they don't need the kind of large-scale power that your X-ray laser battleship would need.

b) Nukes. Imagine the hilarity. Someone puts thousands of nukes in random orbits just for fun. The war starts. Those nukes come to life. It's sort of like a minefield, but where the mines (remote controlled, naturally) have some delta-v to avoid being complete pushovers. Since everything is in motion and there's so much volume, this probably won't help much. If they light up, they are probably easy prey for area defense, but if everything lines up right, it might get a few hits. Worth it? I don't know.

Over interplanetary distances this is problematic because you have to boost them: they're only near the target at a single specific moment. Over orbital distances they're too easy to spot; someone can just turn on their space search radar and see the nuclear warheads that are near them.

Look at the progress we've made here though. It isn't dismissed as physically impossible. We're debating the specifics on how it might be used. Now, our imaginations are the limiting factor rather than science. Our back and forth might represent what two space powers would do in their strategies and counter strategies.

Well, I do think that stealth is of limited utility; the circumstances where it is easiest to avoid detection are also those where you aren't really making an attack with a "ship." You're sneaking a recon probe past at umpty thousand kilometers, or firing a cannonball, or something else.

For an invasion fleet, or for big spacegoing weapon platforms armed with extensive arrays of lasers/particle beams/mass drivers/missile launchers/whatever... it's a lot less viable as a strategy.

What if you had a few submarines tagging along with that merchant ship? That's the key point.

The problem is that in space there is no equivalent to the submarine. Any ship coasting ballistically will be relatively hard to see if it is well designed, and improving the stealth to the point where you make significant compromises on effectiveness to get it (as a submarine does) doesn't give rewards equivalent to the cost.

Ballistic weapons, whose destructive power lies in their kinetic energy, can be a lot stealthier than ballistic ships, large platforms that themselves mount weapons to fire at an enemy.

Dumb weapons can't be ordered to stand down though. What if in those months it takes to get there, the diplomats work out a deal?I'm a bit squeemish at something that might end in killing them all, especially if it can't be undone last minute. Maybe a self destruct on the weapons would work. (Use the same fuse to spread the shrapnel around but with a premature detonation perhaps.)

Easy enough; build a solid fuel rocket engine into the projectiles, pointing perpendicular to the line of flight. In case of an abort, send the go code, fire the rockets, and generate a miss by boosting your cannonballs away.

For projectiles with terminal guidance, there may also be a "deliberately miss" code.

Of course, the problem is that in no case do you have deniability; once you make a sneak attack the enemy will inevitably KNOW you have made one. You can't stop short of the target or deliberately miss it without doing something they can see.

Honestly, lack of easy guilt-free abort options are a predictable price of ballistic sneak attacks. You have to commit to the attack with a lot of lead time, and you can't really unmake it very well without tipping off the enemy to the fact that you were planning to kill them with a sneak attack.

That's one of the reasons I argue stealth isn't very helpful- the context in which it's useful is pretty much limited to "we are at eternal war with no possibility of resolution short of total defeat for one side."

[bz249]

Detecting a ballistic projectile is practically the same as detecting an incoming asteroid (well maybe finding the optimum adsorption coefficient and shape might help a bit). The smaller the projectile the more chance it will get through. I guess if humanity would ever able to wage space war then we would have a reasonably efficient asteroid collision warning system...

The problem is that you really don't need something the size of an asteroid to be dangerous. The real menace from ballistic attacks is that the enemy will use small shots that travel much faster than asteroids (say, around 100 km/s), or small shots that travel at the same speed range (more like 10 km/s) but have terminal guidance that lets them home in on a target as they approach.

Either kind of threat would be much harder to spot than a hundred-meter asteroid, and yet either could carry enough kinetic energy to be very effective as a weapon against spacecraft.

I am not argueing against that deliberately fired projectiles can be more destructive than asteroids of the same size. The asteroid warning system is just gives a lower limit of what we can expect from a civilian tracking system in such a scenario. Any stealth attempt should take this into account.

[Simon_Jester]

Point. Agreed.

[MKSheppard]

How detectable is a 30 kW source?

Hum.

There's a formula for Equilibrium Temperature for Non-Ideal Radiative Heat Transfer for a Sphere in Free Space.

It goes:

T = [ (E • α • AS + PINT) / ( ε • σ • ARAD) ]^1/4

where

E: Irradiance in Watts/m2 from a solar source
α: Absorptivity.
ε: Emissivity.
PINT: Internal heat/power generation in watts.
ARAD: Radiative area in square meters. (Surface area of your ship basically)
AS: Absorption area in square meters. (The area of the side that faces the sun).
σ: Stefan-Boltzmann’s constant, which is: 5.67 x 10^-8 W/m^2 K^4

Some assumptions. This will take place near the center of the asteroid belt; the best place for skullduggery in a solar system.

The amount of solar incidence at a given AU can be discerned through a simple calculation:

E = C • (1/DIST)^2

Where

E: Incidence in W/m2.
DIST: Distance from the Sun in AU's.
C: Solar Constant at 1 AU (1,366 W/m2)

At 2.5 AU; the Solar Incidence is 218.6 W/m2.

We'll assume that your fictional ship is a sphere.

(Spheres make my life easier and are the most efficient in terms of volume/mass/area.)

We'll assume your main hab/weapons/whatnot sphere is 20m in diameter; and it's covered in graphite epoxy or some composite compound like that that is not only dark, but adds to radar stealthiness.

Graphite Epoxy has the following stats for absorption and emmisivity:

α: 0.950
ε: 0.750

Your sphere would have the following specs:

ARAD: 1,256 m2 of surface area that radiates heat
AS: 314.15 m2 of area pointed towards the sun that absorbs heat.

We'll do the calculations for a bunch of power profiles.

30 kW of internal power: 205~K (51-76 times hotter than space)
10 kW of internal power: 193.7~K (48-72 times hotter than space)
6 kW of internal power: 191.1~K (48-71 times hotter than space)
3 kW of internal power: 189.1K (47-70 times hotter than space)
0 kW of internal power: 186.9K (47-69 times hotter than space)

Space is between 2.7 and 4K.

Even flying completely 'dead' or with a super-insulated capsule that soaks up all the heat from your electronics preventing 'leak through', the skin of your spaceship is going to be 47-69 times hotter than space itself due to solar irradance.

Of course, you can get that temperature down through two ways:

• Invest in an active cooling system for the side that's currently pointing towards the threat vector (which will drain your heat sink of it's capacity even faster).
• Paint it in something that has a high α/ε ratio.

If we painted your ship with white paint (α: 0.25 / ε: 0.853); the temperature for 0 kW of PINT would be 129.7K; still some some 32-48 times hotter than space. And by doing this, you've become much more visible to visible light detectors, since you're TEH SHINY.

So how far can we effectively detect an enemy ship?

A good rule of thumb for the resolution of a device is a modified form of the Rayleigh Criterion:

θ = (λ / D)

Where:

θ: Angular resolution of the imaging system in radians.
λ: Wavelength of observed radiation used by the imaging system.
D: Diameter of the lens aperture / Length of the maximum physical separation of devices in an Interferometric Array.

Feeding into that is a modified Angular Diameter Equation:

D = d / [ 2 • TAN(δ/2) ]

Where:

δ: Angular Diameter of object in radians (aka resolution of your imaging system)
d: Diameter of Object.
D: Distance between observer and object.

NOTE: d/D must be expressed in the same unit.

So lets compute two different types of imaging devices.

The first one is a spherical spacecraft 20m in diameter. On each side, we have a truss system that can extend 17 meters; allowing us to create a baseline of 54 meters (54,000,000 μm). We're looking for a target 20m in diameter (the enemy spacecraft); and cranking the formulas results in these maximum ranges:

Visible Light (0.562 μm): 1.9 million kilometers
Near Infrared IR (1.075~ μm): 1 million kilometers
Mid-Wavelength IR (5.5~ μm): 196,300~ kilometers
Long Wavelength IR (11.5~ μm): 93,900~ kilometers

Of course, these ranges are for a 'head on' target that is not generating any appreciable angle-off. If the target is moving at an angle to the sensor; it will be detectable at longer distances, depending on it's own off-angle and speed, by 'smearing' long exposures.

What's truly interesting is if we take two spacecraft and have them flying in "formation" 50 kilometers apart. Their sensors would form a very long interferometric baseline.

At 50,000 meters baseline (50,000,000,000 μm), sensors would have against a 20m target the following ranges:

Visible Light (0.562 μm): 1.78 billion kilometers
Near Infrared IR (1.075~ μm): 930~ million kilometers
Mid-Wavelength IR (5.5~ μm): 181~ million kilometers
Long Wavelength IR (11.5~ μm): 86.9~ million kilometers

If we take your assumption that our weapons can open fire at 2.5 million klicks; and that our ships are moving at a speed of 10 km/sec towards each other for a closing speed of 20 km/sec; even on Long Wavelength IR; we'll detect you 48~ days out with a pair of ships cruising together.

That doesn't even get into the possible absurdities you could create with fairly large sensor arrays at the Earth-Moon L4/L5 lagrange points.

Of course; this is basically imposing very conservative assumptions onto detection technology -- for one, you don't need to resolve something to detect it. However, without resolving it; you will be limited in how much track data you can generate on it.

Amusingly enough; these calculations make small escort ships feasible from the standpoint of acting as a giant sensor for a 'shooter' platform.

A group of six ships would be able to generate a baseline in almost every direction with minimal manouvering needed; and you could have a central ship in the center of the sphere that keeps them stocked up with manouvering fuel and supplies.

You could even have the escorts be completely unmanned with advanced enough technology -- they just dock with the central ship every few months to be checked over in an enclosed hangar, fuelled back up, and then sent out again.

Plus, they become ideal as expendable defense craft -- they can manouver into the way of a missile salvo to help absorb it with their own point defense weapons, or self-detonation.

*give award to the AI of FSC #231231 who sacrificed itself bravely*

[MKSheppard]

Thinking further; the only way you'd truly get stealth in space is if you attached yourself to an asteroid and stayed in the "shade" side.

But that brings a problem.

Whatever it is you sent to hide on the dark side of the asteroid would be tracked going there.

So it would only be a reasonable "stealth attack" method; along with space mines (TM) if the opponent was entering the solar system via some FTL handwavium -- he wouldn't have full trajectory and track data from before hand.

[MKSheppard]

To go back earlier to what I was trying to say about cascade failures:

The 20 July 1992 crash that caused a V-22A to crash into the Potomac river in full view of Congressmen at Quantico was a classic cascade failure.

It started when combustible fluid had begun to leak into the right nacelle during the V-22A's 3~ hour flight from Eglin to Quantico.

It was probably due to a oil seal being installed backwards in the proptor gearbox. Because the plane flew in horizontal flight mode for the three hour flight, the oil collected in the bottom of the engine cowling and sat there.

But when the nacelles tilted for landing, the oil then rushed into the engine where it caught fire. This fire caused an engine surge.

The surge triggered a governor which was designed to prevent engine overspeed and lit off some warning lights. The pilots reset the flight control system to be sure it was a real alarm, which was SOP for the V-22A as it was full of wiring glitches, causing false alerts and alarms.

The Flight control system reset caused both engines to rapidly increase in power, overspeeding both. This caused the right engine to fail.

Now, you're saying, what about that famed cross-link driveshaft that lets one engine drive the other in an event like this?

Because the crosslink driveshaft has to turn 90 degrees to get to the proptor; there's a second driveshaft in each nacelle called the Pylon driveshaft.

This driveshaft in order to save weight was made out of composites. The specific composites that shaft were made of melt at 240F. The fire in the right nacelle was about 900~F.

The driveshaft melted and deformed enough to cause the right proptor to stop. But that wasn't all. Due to it's deformation and because it was still getting power through the crosslink; it then tore through various electrical and hydraulic lines in the nacelle; causing the flight control computer to die and freeze the nacelles in their 58 degree angle that they were found at the bottom of the Potomac River.

...all because someone installed an oil filter backwards.

[MKSheppard]

Temperature is irrelevant. Resolution is irrelevant.

No light, no sight. And there's just not enough light.

You might be correct if this was taking place in interstellar space, where everything cools towards the mean universal background temperature of 2.7K unless it is internally heated.

But in a solar system with one or more stellar objects providing irradance?

Even if we go way past the orbit of Pluto to 50 AU; solar irradance still heats up a white painted object with no internal power to 29K; or 7 to 10 times hotter than space itself.



I'll let NASA explain this:

It's a patch of sky in the constellation Taurus photographed at two different times by the infrared Spitzer Space Telescope. The two frames are correctly aligned; the objects are moving because they are asteroids. At thermal infrared wavelengths, most of the bright objects in the plane of the solar system are space rocks.