Cloaking

[Crazy Eddie]

The heat pumps themselves would generate heat. Even if you managed to isolate the reactors with heat containment systems that were 100% efficient or nearly so, you'd still have the life support to deal with. I just don't think it is at all feasible for a system to be able to hide that much heat from a starship's sensors, at any distance within, say, the diameter of the typical solar system. You'd need to hook up your kick-ass heat pumps to almost every surface of the ship, and those pumps themselves would generate their own heat.

OTOH, the efficiency of any thermal transfer system depends on its ability to move more heat than it generates (and even then, its ability not to add heat back into the system it's removing it from). And all of the problems you described can be solved by simply putting the working parts of the heat pump (compressors, motors, etc) in an insulated compartment where they won't bleed into the ship's environment.

Yeah. Engineering is complicated.

I understand that you disagree and you have some very elaborate theories as to how to get around the problem of stealth in space... but I really think you need to do the math on this if you want to convince me. You say Atomic Rocket is wrong, but Atomic Rocket has some very convincing math to prove itself right. Its going to take math to prove them wrong.

From AtomicRocket's own website:

A full spherical sky search is 41,000 square degrees. A wide angle lens will cover about 100 square degrees (a typical SLR personal camera is about 1 square degree); you'll want overlap, so call it 480 exposures for a full sky search, with each exposure taking about 350 megapixels.

Estimated exposure time is about 30 seconds per 100 square degrees of sky looking for a magnitude 12 object (which is roughly what the drive I spec'd out earlier would be). So, 480 / 2 is 240 minutes, or about 4 HOURS for a complete sky survey. This will require signal processing of about 150 gigapizels per two hours, and take a terabyte of storage per sweep.

He was onto something here, and it bears repeating: a complete sky search at this level of resolution will take about four hours. The only way to speed up the rate of the search is to drastically reduce resolution, which either 1) decreases the effective range of those sensors against the same object or 2) increases the size of the object that the sensors could detect at the same range.

Unfortunately, Ken Burnside then goes on to backpedal with a tangent into the processing requirements of online video games:

Assuming 1280x1024 resolution, playing an MMO at 60 frames per second...78,643,200 = 78 megapixels per second. Multiply by 14400 seconds for 4 hours, and you're in the realm of 1 terapixel per sky sweep Now, digital image comparison is in some ways harder, some ways easier than a 3-D gaming environment. We'll say it's about 8x as difficult - that means playing World of Warcraft on a gaming system for four hours is about comparable to 75 gigapixels of full sky search. So not quite current hardware, but probably a computer generation (2 years) away. Making it radiation hardened to work in space, and built to government procurement specs, maybe 8-10 years away.

This is where he lost me, and it didn't get any better as I read the rest of the page. Because since I happen to know quite a bit about digital image processing (my science teacher and long-time family friend used to work for the JPL) and I know that digital image comparison and 3D gaming are not in the same ballpark, not the same stadium, not even the same sport. Image recognition and image processing--that is, of REAL images, not of pre-programmed images whose parameters are artificially limited--is massively difficult, and now on the cutting edge of even MILITARY sensor devices.

The problem is that a digital image processor has to sift through thousands of different data points with thousands of different signatures and amplitudes, all of which are totally unknown. You're essentially asking the computer to identify a particular needle in a stack of needles. This is easy to do in a 3D gaming environment, where technically the computer already knows where the needle is and simply needs to pretend to go through the motions of finding it. In digital image comparison, simply taking and scanning the images is the EASY part; analysis is complicated enough that it still can't be done automatically unless the computer is programmed to track a very specific pattern in a very specific location (see, for example, image recognition technology in guided missiles).

The only other numbers they put out are those he gets from somebody named John Schilling in a forum post, numbers which are themselves based on another college textbook (and schilling doesn't give the numbers, only the results). Logically, the fact that a given sensors will DETECT your ship from 50 million kilometers is not particularly interesting if your system lacks the ability to RECOGNIZE your ship at the same distance.

and all respect to Ken Burnside, but:

Ken Burnside explains why not. To actively refrigerate, you need power. So you have to fire up the nuclear reactor. Suddenly you have a hot spot on your ship that is about 800 K, minimum, so you now have even more waste heat to dump.

I'm proposing there's no need to dump the waste heat at all. Just recapture it and convert it back into electricity. This is nowhere close to a "perpetual motion" concept since the system requires constant energy input from your reactor system. You don't need to radiate that heat outside the ship, just put it somewhere where the bad guys can't see it. If you can't find anything useful to do with that heat, then just store it there until the bad guys aren't around and then flush the heat tank with coolant when the coast is clear.

 

[JuanBolio]

I can't speak to the speed of sky-scanning with futuristic sensors and computers that measure procesing power in teraquads, but as for using a heat pump to convert waste heat to electricity... why on Earth aren't you working for NASA if this is so easy? The space shuttle has to fly around with its cargo doors open to act as radiators, and it doesn't even run on a reactor - it uses fuel cells! I remain dubious on your thermodynamic math on the heat-to-power solution. It just doesn't seem likely or even possible that you'd be able to hide or re-use enough of that heat to make a difference, especially when you consider that the conversion of that heat to electricity is going to give off heat, the transmission of that electricity through the power systems is going to give off heat, and the utilization of that electricity is going to give off heat.

 

[Crazy Eddie]

I can't speak to the speed of sky-scanning with futuristic sensors and computers that measure procesing power in teraquads

Processing power is irrelevant. At issue here is INTELLIGENCE, which has to do with software. As I again repeat, sky-searches of the type described by AtomicRocket are still not done automatically. Even asteroid searches have to be verified by human researchers because of the enormous amount of false positives and ambiguities in the data, and these searches involve little more than a search for relative motion against a fixed star field. The matter becomes mind-numbingly complicated when searching for something like the thruster plume or thermal signature of a space craft, which can look like just about anything and may or may not be in motion relative to the observer (and may or may not still be visible between sweeps).

Ken Burnside's analysis is based on "torchship" notions, an old sci-fi staple that says that most space craft will use very huge and powerful fusion reactors to fling themselves around the solar system by constantly accelerating at all times. You and I know that most starships in the Trekiverse don't operate this way; when a warp-driven starship needs to travel a long distance in a hurry, it will simply jump into warp drive, which renders a sky search pretty useless and you're better off switching to gravitic sensors and listening for the echo from his warp field.

as for using a heat pump to convert waste heat to electricity... why on Earth aren't you working for NASA if this is so easy?

I said it is easy, not CHEAP. And heat pumps and their assorted machinery are also very very heavy.

OTOH, they did something like this on Skylab, recycling heat from the skin of the craft and using it as a source of hot water. Apparently this is somewhat easier to do on solar-powered space craft that have more spare energy to use for active coolant systems.

On still the other hand... need I point out the obvious fact that neither NASA nor the Russians have ever attempted to build a space craft that doesn't radiate excess heat into space? I'm not even saying the technology has been implemented, I'm saying it COULD be if someone needed to, using technology we already have.

It just doesn't seem likely or even possible that you'd be able to hide or re-use enough of that heat to make a difference, especially when you consider that the conversion of that heat to electricity is going to give off heat, the transmission of that electricity through the power systems is going to give off heat, and the utilization of that electricity is going to give off heat.

In a situation involving a cloaked vessel, much of that energy is already radiated away from the ship in the form of whatever forcefield you're using to hide yourself. Such a system would undoubtedly have very poor energy efficiency with prolonged usage (since it's only reclaiming about 10% of the heat it pumps back out of the ship) but it would be harder to detect in the long run, and it solves your "overheating" problem very nicely. If for some reason the Romulans can't design a decent heat exchange system that can store that excess energy somewhere useful, they can always channel it to a "hotbox" somewhere in the nacelles and then flush them with coolant every, say, ninety five minutes so that any starship looking for them would have to be looking directly at them the moment they performed a coolant purge to have a chance to pick them up (which, again, is highly unlikely at long ranges).

 

[JuanBolio]

You certainly back up what you say, although I must admit not convincingly enough to satisfy me completely. I still maintain that cloaking or any form of stealth in space (short of hiding behind something) is realistically implausible, short of some future material/principle we don't yet know about - I.E. unobtanium and handwavium. However, Star Trek has never been terribly accurate in terms of science realism, so this can all be forgiven. Cloaking makes for an interesting plot device, and that's all it was ever intended to be.

By the way - there are two key factors in detecting a ship's heat signature by computer that would make it all considerably easier than you've made out. Distance (which can easily be determined), and relative motion/acceleration (which would be even easier to pick out).

 

[Crazy Eddie]

By the way - there are two key factors in detecting a ship's heat signature by computer that would make it all considerably easier than you've made out. Distance (which can easily be determined), and relative motion/acceleration (which would be even easier to pick out).

Distance can only be determined once you've worked out the target's position with enough precision to triangulate it using a rangefinder. If you don't know the distance ahead of time, identifying something "too close to be a star" just isn't going to happen unless you're bouncing a laser beam off every conspicuous heat source in the cosmos.

Motion/acceleration works out well in the torchship scenario, but only in the Ben Bova/Larry Niven style scenarios where the maximum velocity of any space craft is on the order of a few hundred kilometers per second and interplanetary flights are measured in weeks or months; in this case, a four hour sky search for an accelerating torchship could easily detect an anomalous heat signature in two different places, then using a simple "Eliminate the difference" algorithm and focus a more detailed scan in that direction to identify it (which is more or less what the Minor Planet Survey does, except the things they're looking for are much less obvious, hence the large number of false positives). This would make it trivially easy for the Enterprise to get a fix on, say, the SS Botany Bay making a slow dash across the solar system with its big sub-impulse fusion drive blasting away for six consecutive months. The Botany Bay is at a disadvantage, though, because by the time their sensors pick out the Enterprise's impulse engine heat signature, the ship has already gone to warp and left the area days ago.


I'm not even saying that trek sensors are blind and dumb. Actually, for fanfic purposes I use a similar set of assumptions as these and I figure that gravitic sensors (which for some reason are FTL devices) can complete a full sky search out to a distance of, say, 500,000km in about 60 seconds; this sweep can only resolve an object with a mass of at least fifty thousand tons, so searching for a smaller object would require a more thorough (and therefore longer) search. Divide the lowest resolution by two and double the sweep time, meaning that in order to detect a ship with a mass signature of about 10,000 tons, it has to complete five sweeps, or about five minutes of scanning time.

If part of what a cloaking device does is hide the gravitational distortion from the ship's mass (say, making a 90,000 ton vessel look like a 10,000 ton one) then this vessel can evade detection by a scanning starship for up to five minutes before an anomaly is detected. During this five minutes it can take evasive action to avoid detection, up to and including accelerating to high impulse and dropping back out of range, or going to warp and repositioning before the enemy can get a fix. Other sensors (lidar, radar, EM/multispectral, etc) would have similar limitations, such that a cloaked ship needs only reduce its radar/lidar/EM cross section enough that it takes longer for a scan to detect it, giving them a bit more time.

In practice, it would work like one of those old submarine movies, where the sonar operator "thinks" he hears something and tries to zero in on it. If he's lucky, maybe he'll pick up another signature on a different set and realize he's looking at an impulse engine flare and report to his captain that there's a possible cloaked ship at such and such a coordinate. If he's not lucky, he'll keep analyzing it until just before the Romulan ship decloaks and opens fire, having successfully evaded detection until it's too late.

 

[CuttingEdge100]

The problem with cloaking is that the ship cannot realistically use a fusion engine as it's IR signature would be easily spottable. The Enterprise would have had to have had infrared sensors onboard.

So the next logical assumption would be that it would use warp-engines in sub-light use as it would produce no exhaust that could be hit. However, here presents another problem, the warp-field and it's distortional effects on space would be detected. I don't know how the hell you'd hide that. Also the ship would need to have it's nav-deflectors on to some degree even at sub-light speed to avoid getting creamed by small-debris which would also be visible.

I suppose if you could hide all that you'd have a workable system, and the energy output would be pretty gigantic as described. Of course you'd have to somehow mask the warp-field and nav-deflector without actually neutralizing them. Otherwise the ship wouldn't go anywhere and the deflectors would be useless.

But assuming you could do that, the next obstacle would be that the ship would have to be able to see through it's own cloak.

If that could be overcome, then what would prevent them from being able to get a passive-weapons lock? A passive sensor can acquire a target too, and modern day (Early 21st century) we have LOAL (Lock-on After-Launch) capability with missiles. Basically you fire it and it either selects its own target after launch, or the launch vehicle then signals it telling it to take out a desired target. Photon Torpedoes as explained in Star Trek are basically fancy missiles with warp-capability and matter/anti-matter warheads.

The answer is that there is no reason it could not fire it's torpedoes while cloaked. This would limit it's ability to engage a target over long range as it would not have active subspace scanners working (which would reveal it's location), and would rely mostly on lightspeed sensor readings. I suppose a passive subspace scanner could be used, picking up subspace signals produced by other vessels, but it might have limitations, though I'm not sure. For one, subspace signals are FTL waves and are entirely artificial. The other ship if they knew a cloaked vessel was in the system they'd just shut them off. On the other hand though, passive subspace scanners might include scanners that detect warp-fields (although I'm not sure if that would fall under passive or active), and even impulse vessels usually use low-warp to help improve acceleration, so it might be able to do just fine working on just passive sensors.

It sounds quite overboard to have cloaked ships traveling at warp while cloaked. The amount of energy to hide a warp-field that is able to distort space to a level that the vessel can travel dozens to hundreds of times speed of light, and the ability to produce a deflector field that would reach out far enough to sweep away anything would be massive and the amount of energy to hide all that would be obscene even by Star Trek standards

 

[Crazy Eddie]

The problem with cloaking is that the ship cannot realistically use a fusion engine as it's IR signature would be easily spottable.

Hiding the IR signature is probably a major part of what the cloaking device does. It doesn't seem to only act against active scans, it needs to have the ability to handle passive emissions from the ship that uses it, especially since a captured cloaking device is able to hide a starship (like the Enterprise) that isn't designed to use it.

It probably phase-shifts the IR emissions into something on a lower spectrum, like S-band radio or something, the sort of emissions a sensor might not be looking for. Or (as I did once in a fanfic) the shift the emissions into higher frequencies by converting IR emissions into upper UV frequencies which might otherwise be mistaken for hydrogen cloud reflections or some natural phenomenon. This solves the thermal problem, too, since the cloaking device would have to add energy to those emissions to raise their frequency and therefore the device itself might function as a heat sink.

 

[Unicron]

I always kind of liked the idea that Trekverse ships had to have a balance of system power, and that the reason it's difficult to fire and cloak at the same time is in part to keep the cloak effective. Without that, it might be too easy for a ship to simply sneak up behind an enemy and attack with impunity. Star Wars cloaks seem to have the "double blind" problem CuttingEdge mentions and are somewhat rare.

StarCraft cloaks don't seem to cause a problem in terms of weapons, since they're self contained modules on Terran units and the Protoss have more advanced cloaks. However, it's also fairly easy to detect a cloaked unit with the right equipment, and that naturally negates the stealth advantages.

 

[Crazy Eddie]

^ Well, with the right equipment you can negate ANY advantage, even in the Trekiverse. The trick is knowing how to avoid people who have the right equipment.

 

[Anwar]

That's probably why they don't have the cloak-fire thing after TUC: the cloak arms race produced anti-cloak weapons for the Feds that made them develop a better cloak that no longer allowed the fire-while-cloak option.

 

[Timo]

Or then it was found useless to maintain cloak through firing - because modern fire control systems could make use of the couple of seconds the cloaked target is illuminated by its own fire.

OTOH, Kirk's gas-tracking torpedo would probably be a useless weapon with minimal countermeasures, such as erratic maneuvering with occasional switching off of the gas-belching engine, or emission of decoy gas clouds. Hell, it was probably useless to begin with, because most battlefields would be saturated with the exhaust gases of multiple vessels in zigzagging and crossing lines. It was just good luck that the torp didn't home in on Kirk's own engines, and that it eventually found Chang's.

Timo Saloniemi

 

[CuttingEdge100]

Timo,

That's a good point. I don't think they would have been in danger of shooting themselves, but they might have been in danger of shooting the Excelsior. That vessel is huge and is far more massive than the Enterprise, and it's engines are quite large compared to the Enterprise.

The exhaust gases from the Enterprise would be behind the torpedo, though there is no rule to say a torpedo cannot home in on a target behind itself (there are missiles that have a 360-engagement envelope such as the Rafael Python V) but obviously the people who made the movie didn't think this through as

1.) Kirk and Spock are both extremely intelligent people and would have taken that into account, either shut the engines off when firing or programmed in a "no engage" zone around the impulse decks.

2.) If ships that were cloaked did emit thermal signatures, the Enterprise even in TOS time would have been easily able to identify the target as it had all sorts of sensors including electro-optic (how do you think the view-screen works?) and infrared.

 

[Vanyel]

Timo,

That's a good point. I don't think they would have been in danger of shooting themselves, but they might have been in danger of shooting the Excelsior. That vessel is huge and is far more massive than the Enterprise, and it's engines are quite large compared to the Enterprise.

The exhaust gases from the Enterprise would be behind the torpedo, though there is no rule to say a torpedo cannot home in on a target behind itself (there are missiles that have a 360-engagement envelope such as the Rafael Python V) but obviously the people who made the movie didn't think this through as

1.) Kirk and Spock are both extremely intelligent people and would have taken that into account, either shut the engines off when firing or programmed in a "no engage" zone around the impulse decks.

2.) If ships that were cloaked did emit thermal signatures, the Enterprise even in TOS time would have been easily able to identify the target as it had all sorts of sensors including electro-optic (how do you think the view-screen works?) and infrared.

Or they could have programed the torpedo to ignore the Enterprise's impulse trail (radiation, thermal whatever that would make it more Federation than Klingon).

 

[Timo]

I'd think our heroes wouldn't have had time for that. They'd just dump in the gas sensor, launch the torp, and see if it worked. If it started heading towards them, they'd use a standard scuttling system they hopefully wouldn't have removed from the torpedo... Either automated, with programmed no-engagement zones, or simple manual. Certainly the torp would otherwise be capable of hitting the launching ship, considering the loops it is shown making.

It would require a bit more R&D to devise a torp that could differentiate between Klingon and Federation trails, I guess. And the trails would probably be modifiable, making the task difficult.

It's something of a misconception, probably, that Trek cloaks would be working against the background of empty space. A typical battlefield would be a messy place where a cloak could be incomplete and still not reveal anything that would immediately stand apart from the background. It would only be in pre-combat situations where a cloaked ship might have trouble sneaking in - a situation that is familiar to submariners today. And no doubt cloakship captains, just like submarine ones, would make maximal use of local conditions and anomalies to facilitate the sneaking - a task made easier by the greater prevalence of anomalies in the Trek outer space as compared to our own...

Timo Saloniemi

 

[USS Jack Riley]

I would think that since the equipment used to help the torpedoes hone in on Chang's shope were already used to study gaseous anomalies, they were also already programmed to eliminate the Enterprise as a source of similar gaseous anomalies, plasma venting, etc.

YMMV

 

[Crazy Eddie]

Or it could have been a last desperate gamble by a starship that was being crucified alive by its target and didn't have any cards left to play.

As is often the case for ships named Enterprise, it's better to be lucky than smart.

 

[CuttingEdge100]

There is of course one major flaw in Star Trek VI. The Enterprise wasn't charting gaseous anomalies -- the Excelsior was...

 

[Unicron]

But it might carry standard equipment for doing work similar to what the Excelsior does at the beginning of the movie, just perhaps not as much.

 

[JuanBolio]

There is of course one major flaw in Star Trek VI. The Enterprise wasn't charting gaseous anomalies -- the Excelsior was...

Doesn't mean the Enterprise wasn't, or couldn't. Perhaps it was fleet-wide catalog gaseous anomalies month.

 

[Timo]

I'd point out that a previous version of the script indeed referred to yet another "Meyerism", a blatant Star Trek analogy to the first International Year of Geophysics (1957-58) that was another Cold War milestone and involved military vessels performing seemingly innocent scientific research that had very important strategic uses, so that in this script version all Starfleet vessels were indeed carrying gaseous anomaly analysis gear at that time...

...But I don't believe in unfilmed scripts as part of the Trek universe.

Nevertheless, mention of this was made in an unfilmed scene where Kirk toured the Klingons around his ship. And it does make sense, even if left unmentioned. As a bonus, it casts the mission of the Excelsior in a different, darker light: a mighty warship doing "scientific research" just next to the Klingon border is ominous enough, but when coupled with this International Year of Geophysics analogy...

Timo Saloniemi