T4 Only: Some people say no stealth in space, a discussion.

[warwizard]

Well distance does reduce the number of photons per second that a given sensor with area of X can detect. Lets start with black body radiation. An object that is at equilibrium with it's environment gives off photons of total energy equal to the total energy of all energy being asborbed. An object in intergalactic space and has been there for 100 billion years, will asborb the energy of all the photons that it's surface captures plus all of the nutrinos that it's bulk mass captures. In addition it's surface may be reflective, or not so much. So even this object at .00001K still will bounce photons, it's gravity will bend photons that pass near, and give off black body radiation, as well as block photons. However here is the rub, How far away is the sensor, how much area does it have and what is the minimum photons per second that can result in a detection? My Mk 1 eyeballs have a very small sensor area, and require a lot of photons per second, to establish a detection. I am totally sure that my Mk 1 eyeballs have never reported seeing that 1m rock floating somewhere between the Milky way and Andromada galaxies. Therefor, for that set of object, distance and sensor, indeed that rock is stealthy.

The next thing is how usefull is this detection? What is the purpose of the detection, and what is the response time needed. Detecting the 1 m rock in intergalactic space, EM radiation from that rock took somewhere between .5 and 50 million years to reach earth, we had to wait 20 million years to collect enough photons to establish that something is there. However the response time needed is the average lifespan of the civilizations we create. We cannot use the detection for our society fails to have enough time to detect it.

So given that I have established that we CANNOT see everything, let us agree that indeed some things cannot be detected due to not enough packets of energy over time. Now, what if we constrain the object to be something within the Heliopause of a solar system, it has internal environment maintaining 273 degrees K, and we have one month to establish a usefull detection. Further limitations is that it arrived at it's location via jump, thus creating an energy spike as defined in the rules. Now we need to know something about the sensor abilities of the society/civilization in that system. TL 0 with Mk 1 eyes are never going to detect any but the ones trying to be seen (Circumpolar orbit with million candle power strobe lights!). Glass lenses should be able to be created at TL 0, however not many will be made so sensor coverage will be sparce and the sensors are now Mk 2 eyeballs with lenses perhaps 100X the photon gathering ability.

So the tech level of the sensor and the society's ability to build stuff affect sensor sensitivity and coverage. TL 4 pop 4 will not have much sensor coverage compaired to TL 4 pop 8, So the primary sensor ability is a fuction of tech level and population. The no stealth in space folks would agree that the TL 15 pop A folks will have a much easier time detecting due to sensor technology and coverage. So the question comes down to just one of technology and scale verses technology, size, and distance. My thought here is that there will allways be a Technology*Size*Distance that will not be detectible within a given Technology*Scale*Time. Let's discuss!

 

[infojunky]

Ok, T4... A lot of the assumptions made there were highly optimistic. Especially for passives.

 

[warwizard]

Ok, T4... A lot of the assumptions made there were highly optimistic. Especially for passives.

As I am arguing against the no stealth in space, I wanted to give the sensors the best chance. I left off the atmospheric attenuation/distortion/obstruction issues for TL 6-. There are a lot of things that you realize rather quickly when you start looking in FF&S T4 sensors. #1 active sensors broadcast your position at 2X the distance you could make an active detection with them, so are only used when you know you are already spotted, and need to be sure to detect the stealthed micro missiles that you know they launched a half hour ago. This means that the passive sensors will be the sensor to rely on for the first detection of the contact.

 

[kilemall]

Not being that interested in totally hard science and interested in easy to reuse existing ship designs, I have three assumptions -

1) the maneuver drive’s gravitic field has a distortion effect that renders the basic CT like ranges in play

2) detection isn’t target solution, there is something out there and then actual lock on yielding correct tonnage, observed emissions, etc and it’s easier if either the target is active or your sensors are

3) range is a function of computing power plus hull size, I assume hull mounted VLA type sensor arrays, and TL determines maximum maintain detection range

So for the latter I use computer model and the ship size modifier from High Guard. Smaller then 1dton objects like rocks, missiles get -3 DM.

Radio and laser comms are an exception to CT ranges as they are designed for extra long distance. Even then, the capacity of the comm sets’ range is determined by the same computer model/hull size plus whether it has a small craft/ ship bridge and/or enhanced sensors for that range of EM.

Speaking of, for each computer model number a specific EM band or other long range sensor can be added. Small craft bridge gets a free radio plus one short range EM detector (short range being the doggo range as modified by computer) and boat/ship bridges get an entire short range suite of all detectors (which include things like particle detection and sound).

This means that technically every ship can do a planetary survey, but usually do not have the crew or computer programs to do so, and how even hand me down Seekers can prospect.

As to the practical range concerns, mostly that is either weapons or detecting space hazards like rocks or solar flares and avoiding them. Therefore you have a maximum safe vee based on the combination of detection range and G available to change course and avoid.

 

[mike wightman]

There is no stealth in space for a fusion powered spacecraft maintaining an internal temperature of 291K (273 is ~ 0 Celsius)
unless you have space magic to hide the waste heat.

The JWST could spot it no problem.

 

[TamsinP]

There is no stealth in space for a fusion powered spacecraft maintaining an internal temperature of 291K (273 is ~ 0 Celsius)
unless you have space magic to hide the waste heat.

I beg to differ - there is stealth in space. It's called hiding behind an object bigger than yourself.

 

[Marcatlas]

I allow detection of a ship anywhere in the system with passive sensors within an hour (6 minute turns). However, that just gives a direction. Not range, speed course, ship size. Those take longer based on distance. Ya just can't escape a TL 7 Far IR scope and a good graphics card running on a 1999 era fast PC.

 

[Spinward Flow]

The mistake that people keep (repeatedly) making is that sensor detections are both "easy" as well as "free" ... so on the task scale they fall below the difficulty of "routine" and just become "automatic" (so don't even bother checking with dice). This fallacy stems from the idea that sensors are PERFECT in tracking all bands, simultaneously, in all directions ... simultaneously. There is a 360º by 360º volume sphere around your craft where you know EVERYTHING ... INSTANTLY ... without fail ... or even needing to rhyme or reason why.

Meanwhile, the difference between diffuse reflection and specular reflection get completely ignored (because it's inconvenient).

Worse yet, people all too often associate "stealth" with what amounts to a Cloaking Device (or straight up "invisibility").
Stealth is NOT (only) ... this ...

Perhaps it would help to use different words to adequately describe what is going on.



Everyone playing Traveller ought to be familiar with the concept of vehicle and weapons (fire) signatures.
In CT Striker, these are straight up modifiers that determine how easily certain things (like vehicles and weapons fire) can be detected on sensors.

Bigger vehicles = easier to detect
Hotter weapons fire = easier to detect (with plasma and fusion guns being an automatic detection)

So if design parameters such as dimensions/size and and weapons fire can have +DMs to sensor signatures ... it stands to reason that what stealth is doing is engineering a way to -DMs to sensor signatures (in various bands).

The "goal of stealth" is to simply REDUCE SENSOR SIGNATURES ... meaning apply a -DM to signature, rather than a +DM.
Ideally speaking, you want your -DM to signature to be of sufficient magnitude that it renders sensor detection "hopeless at useful distances" yielding a functional invisibility rather than requiring actually perfect invisibility.



And to all of the closed minded folks reading these forums who think that "signature reduction in space" (otherwise known as "stealth") is simply impossible to achieve (so don't even bother trying!) ... ... we already have THOUSANDS of real world examples of the effectiveness of signature reduction IN SPACE in orbit around Terra right now (in real life!).

The first Starlink satellites launched by SpaceX did not go far enough with their signature reduction engineering, causing the low orbiting satelltes to be (too) easily detectable from the ground ... either by the naked eye or by ground based telescopes.

SpaceX iterated their satellite designs to engineer a reduction in signature ... so as to "stealth" them (somewhat) ... in the night skies. This does not make the Starlink satellites "invisible" (per se) or otherwise "impossible to detect" with sensitive enough instruments (such as really high power ground based telescopes), but the later generation satellites DO HAVE a markedly lower "signature profile" than the earlier generation(s) of satellites.

That is an example of "stealth in space" (although the term "signature reduction in space" would be more accurate) being done with real world TL=7-8 engineering for something as simple as communications satellites in orbit around a planet. The design intent of the signature reduction is to reduce the (optical) reflective signature of the satellites relative to observers on the planetary surface below, rather than being some kind of "all aspect/all directions" type of magical "invisibility field" (or cloaking device, if you prefer).



Now, if signature reductions can be done for commercial communications satellites in orbit ... then signature reduction can be engineered into spacecraft and starships ... UNDER CERTAIN CONDITIONS.

Are those conditions going to be an "always on" or otherwise "automatic" thing?
Well ... with a BLACK GLOBE in operation, at a far enough distance from the sensor (so there isn't a trace of background stars getting successively eclipsed) ... effectively, YES.

But in the absence of an operating Black Globe, there ARE going to be ways to engineer a craft to present a reduced sensor signature ... otherwise known as "stealth" in many circles. How EFFECTIVE that engineering is under a variety of conditions, situations and circumstances ... can vary wildly.

For example ... a specular reflection light scattering system tuned to the dominant spectrum wavelengths of a G2 V (5500º K photosphere) star may actually perform poorly when illuminated by other types of stars ... such as a M5 V (2900º K photosphere) star.

At higher tech levels, where you have fusion power and neutrino sensors, things get a bit more complicated.
Fusion reactors will release neutrinos that a neutrino sensor will be able to detect (relatively automatically).
Solution?
Temporary shut down of a fusion reactor (denying the automatic sensor detection of a neutrino signature) and flying on orbital inertia (zero delta-v) and battery/capacitor power to "get past a sensor net" of neutrino sensors can work. For those readers who enjoy their historical parallels between wet navy experience and spacecraft, this is the equivalent to a "submarine diving" and then "silent running" while drifting past an adversary.



My point being that thinking of "stealth in space" as some kind of "all or nothing" sort of deal (or worse, as an invisibility/cloaking device) is the wrong way to think about the issue. It's tantamount to making damage results from small arms fire result in either "no effect or dead" as the only two options.



Is it *possible* to reduce a craft's signature on sensors while that craft is in space?
Yes.
Does reducing a craft's signature put constraints on how the craft can be operated while in space?
YES.
Even turning a Black Globe ON/OFF puts constraints on how a craft can be operated in space, which LBB5.80 covered explicitly.

 

[chipla]

2) detection isn’t target solution, there is something out there and then actual lock on yielding correct tonnage, observed emissions, etc and it’s easier if either the target is active or your sensors are

I think this is a very important point. Knowing something is there is different from knowing who or what is there.

A significant proportion of ships operating lawfully would have transponders on etc so your average civie merchant ship isn’t going to have a high end threat analysis suite comparing stated identity with emissions etc.

I suspect most “stealth” in a military context would actually be about emissions control and trying to convince the threat analysis software/ratings on the other side that you’re something else or adding just enough confusion into the mix to provide reasonable doubt as to the actual identity/class/loadout of the ship.

 

[Marcatlas]

I think this is a very important point. Knowing something is there is different from knowing who or what is there.

Exactly, while it is easy and almost free to detect if a ship exists via IR sig it is much more difficult to pinpoint it and determine size, etc. That involves moving the ship to get a long enough baseline for accurate distance measurement and additional observations to get a speed, course, etc.

 

[Spinward Flow]

I suspect most “stealth” in a military context would actually be about emissions control and trying to convince the threat analysis software/ratings on the other side that you’re something else or adding just enough confusion into the mix to provide reasonable doubt as to the actual identity/class/loadout of the ship.

Do not forget that in LBB S4, the Corsair detailed on p14-15 includes this tidbit detail ...

The ship has several centrally controlled identification features which can alter the shape and configuration of the ship at a moment's notice; fins retract or extend, modules appear or disappear, and radio emissions alter frequency and content. The ship's transponders can be altered to identify the vessel as having any of a variety of missions and identities.

SPOOFING YOUR IDENTITY as a craft in space has been A Thing™ in CT almost from the beginning.

I can even make the case that this kind of transponder spoofing by a "malign actor" is the actual reason behind one of the TAS News Reports prior to the Fifth Frontier War.

Fifth Frontier War, p6:

DENTUS/REGINA (2605-C979500-A S
361-1105

Word was received today that two weeks ago the Imperial Battle Cruiser Adamdun mistakenly engaged and destroyed the merchant craft Bloodwell of the Oberlindes Lines. The Bloodwell, according to the crew of the battle cruiser, was not showing its ID transponder signal and would not answer broad-beam hails. The ship was under full acceleration and, after it refused to change vector in response to laser warning fire, was engaged by high-G missile fire and destroyed. A subsequent (and unsuccessful) search for survivors resulted in the identification of the ship.

Oberlindes Lines officials called the story “an obvious cover-up of a tragic display of incompetence” and claimed that the Bloodwell’s ID transponder had just undergone its annual maintenance check and could not have failed to function. As in all commercial vessels, the ID transponder was supposedly tamper-proof and could not have been turned off by the crew. Legal action is expected.

A "careful reading between the lines" of that news report, if NOT taken at face value ... offers a different possibility.

Note: Adamdun is a Kinunir class battle cruiser (the last built that remains in service, actually).
LBB A1, p11:

No.	Name	Laid Down	First Flight	Builder	Fate
9531	Adamdun	140-1086	247-1089	Clan Severn	in service

A malign actor with spoofing enabled on their transponder "hijacked the identity" of the merchant craft Bloodwell to navigate an encounter with the Battle Cruiser Adamdun ... effectively letting the malign actor get "waved on through" so they could go about their business.

LATER ... the REAL merchant craft Bloodwell showed up (unexpectedly), the officer on watch of Adamdun jumped to the WRONG conclusions (with confidence) thinking that they were NOW dealing with a case of stolen (transponder) identity. The first ship spoofed them (successfully), so now there is an assumption of "Fool me once/Fool me twice" going on.

Adamdun opens fire with lasers, in a classic "shot across the bow" fashion.
Problem is ... in space ... there's no "water" for the cannon ball to "splash" into.
In fact, in the vacuum of space, lasers (even weapons grade!) are difficult to detect if they don't hit anything and aren't pointed RIGHT AT YOU ... meaning that they're pretty much worthless for any kind of "shot across the bow" warning to a civilian ship. A military sensor suite (and crew) might be able to detect the laser fire "shot across the bow" but a civilian ship with a model/1 or 2bis (at most) probably isn't going to even notice laser fire that doesn't hit them (or anything else nearby to them).

So the laser "shot across the bow" provokes NO RESPONSE from a civilian merchant ship.
The officer on watch on Adamdun orders missile fire and destroys the merchant craft Bloodwell.
Oops!



In this case, I'm thinking that Oberlindes Lines officials calling the story “an obvious cover-up of a tragic display of incompetence” is absolutely spot on.

1. At no time could the merchant craft Bloodwell have outmaneuvered or out accelerated the Imperial Battle Cruiser Adamdun, so the opportunity to "escape" (except by jumping) was never there. The merchant craft Bloodwell was under "full acceleration" (which probably meant 1G, let's be real here ) and probably not in any preparation to jump at any time soon ... and if they were, the sensor suite on Imperial Battle Cruiser Adamdun could have easily determined that fact.
2. Laser fire "across the bow" in space is going to be an extremely INEFFICIENT way of signalling to an unresponsive craft that "the party lights are on and you need to pull over/heave to and prepare to be boarded" (or words to that effect).
   
3. What SHOULD have been done is to use MISSILES ... not LASERS ... for the "shot across the bow" (missing intentionally) to get the attention of the unresponsive merchant craft Bloodwell ... and then train the lasers onto the merchant craft Bloodwell if the missile fire failed to get their attention. The news report states that the merchant craft Bloodwell was under full (probably 1G) acceleration and refused to change vector in response to the laser warning fire. That means that the merchant craft Bloodwell wasn't exactly maneuvering evasively (at 1G, c'mon ) and would have been an EASY target for the laser batteries of a Kinunir class battle cruiser capable of 4G acceleration.

An even more "mundane" explanation of the tragic events is that the Adamdun communication suite malfunctioned, so the "broad-beam hails" to merchant craft Bloodwell either weren't sent or the responses were not received. The officer on watch probably assumed that "nothing was wrong with THEIR ship" ... let the victim blaming commence.

And then when the scope of the tragedy was revealed ... the crew of the Imperial Battle Cruiser Adamdun immediately moved into making “an obvious cover-up of a tragic display of incompetence” for their deplorable actions.

However, I personally like to think that "there's more to the story" than just simply an incompetent bridge officer makes dumb mistake. I like to think that the "dumb mistake" was prompted by an EARLIER encounter with a malign actor who successfully spoofed their transponder ID during an interaction with the Imperial Battle Cruiser Adamdun with effects that reverberated into this tragedy concerning the merchant craft Bloodwell.

I like to think that "once bitten, twice shy" helped to contribute to the bridge officer overreacting and assuming that everything aboard their battle cruiser was "perfectly operational" and there could not be an "own side failure" of any kind, therefore that damned merchant is just cruisin' for a bruisin' ... so let's give it to them!

Meanwhile, the malign actor who (successfully) spoofed their way past a Kinunir class battle cruiser in the Dentus system is still out there somewhere ...

 

[mike wightman]

A useful video or two:

 

[TamsinP]

Do not forget that in LBB S4, the Corsair detailed on p14-15 includes this tidbit detail ...

SPOOFING YOUR IDENTITY as a craft in space has been A Thing™ in CT almost from the beginning.

I can even make the case that this kind of transponder spoofing by a "malign actor" is the actual reason behind one of the TAS News Reports prior to the Fifth Frontier War.

Fifth Frontier War, p6:

A "careful reading between the lines" of that news report, if NOT taken at face value ... offers a different possibility.

Note: Adamdun is a Kinunir class battle cruiser (the last built that remains in service, actually).
LBB A1, p11:

No.	Name	Laid Down	First Flight	Builder	Fate
9531	Adamdun	140-1086	247-1089	Clan Severn	in service

A malign actor with spoofing enabled on their transponder "hijacked the identity" of the merchant craft Bloodwell to navigate an encounter with the Battle Cruiser Adamdun ... effectively letting the malign actor get "waved on through" so they could go about their business.

LATER ... the REAL merchant craft Bloodwell showed up (unexpectedly), the officer on watch of Adamdun jumped to the WRONG conclusions (with confidence) thinking that they were NOW dealing with a case of stolen (transponder) identity. The first ship spoofed them (successfully), so now there is an assumption of "Fool me once/Fool me twice" going on.

Adamdun opens fire with lasers, in a classic "shot across the bow" fashion.
Problem is ... in space ... there's no "water" for the cannon ball to "splash" into.
In fact, in the vacuum of space, lasers (even weapons grade!) are difficult to detect if they don't hit anything and aren't pointed RIGHT AT YOU ... meaning that they're pretty much worthless for any kind of "shot across the bow" warning to a civilian ship. A military sensor suite (and crew) might be able to detect the laser fire "shot across the bow" but a civilian ship with a model/1 or 2bis (at most) probably isn't going to even notice laser fire that doesn't hit them (or anything else nearby to them).

So the laser "shot across the bow" provokes NO RESPONSE from a civilian merchant ship.
The officer on watch on Adamdun orders missile fire and destroys the merchant craft Bloodwell.
Oops!



In this case, I'm thinking that Oberlindes Lines officials calling the story “an obvious cover-up of a tragic display of incompetence” is absolutely spot on.

1. At no time could the merchant craft Bloodwell have outmaneuvered or out accelerated the Imperial Battle Cruiser Adamdun, so the opportunity to "escape" (except by jumping) was never there. The merchant craft Bloodwell was under "full acceleration" (which probably meant 1G, let's be real here ) and probably not in any preparation to jump at any time soon ... and if they were, the sensor suite on Imperial Battle Cruiser Adamdun could have easily determined that fact.
2. Laser fire "across the bow" in space is going to be an extremely INEFFICIENT way of signalling to an unresponsive craft that "the party lights are on and you need to pull over/heave to and prepare to be boarded" (or words to that effect).
   
3. What SHOULD have been done is to use MISSILES ... not LASERS ... for the "shot across the bow" (missing intentionally) to get the attention of the unresponsive merchant craft Bloodwell ... and then train the lasers onto the merchant craft Bloodwell if the missile fire failed to get their attention. The news report states that the merchant craft Bloodwell was under full (probably 1G) acceleration and refused to change vector in response to the laser warning fire. That means that the merchant craft Bloodwell wasn't exactly maneuvering evasively (at 1G, c'mon ) and would have been an EASY target for the laser batteries of a Kinunir class battle cruiser capable of 4G acceleration.

An even more "mundane" explanation of the tragic events is that the Adamdun communication suite malfunctioned, so the "broad-beam hails" to merchant craft Bloodwell either weren't sent or the responses were not received. The officer on watch probably assumed that "nothing was wrong with THEIR ship" ... let the victim blaming commence.

And then when the scope of the tragedy was revealed ... the crew of the Imperial Battle Cruiser Adamdun immediately moved into making “an obvious cover-up of a tragic display of incompetence” for their deplorable actions.

However, I personally like to think that "there's more to the story" than just simply an incompetent bridge officer makes dumb mistake. I like to think that the "dumb mistake" was prompted by an EARLIER encounter with a malign actor who successfully spoofed their transponder ID during an interaction with the Imperial Battle Cruiser Adamdun with effects that reverberated into this tragedy concerning the merchant craft Bloodwell.

I like to think that "once bitten, twice shy" helped to contribute to the bridge officer overreacting and assuming that everything aboard their battle cruiser was "perfectly operational" and there could not be an "own side failure" of any kind, therefore that damned merchant is just cruisin' for a bruisin' ... so let's give it to them!

Meanwhile, the malign actor who (successfully) spoofed their way past a Kinunir class battle cruiser in the Dentus system is still out there somewhere ...

Then again, from The Traveller Adventure we know that Oberlindes Lines have access to transponder spoofers, presumably in common use as their technicians are able to install it on the March Harrier and show the crew how to use it. Which could very well mean that the Bloodwell was using one and someone on the ship was accidentally transmitting as another ship.

 

[Condottiere]

If used to reduce thermal signature, a chill can is good for around four hours, during which time the user’s thermal signature is reduced almost to background levels. This imposes DM-4 on attempts to detect, track or target the individual using thermal sensors. By the end of the period the unit is saturated and thermal suppression is lost. The gel does not reach high temperatures; little more than the user’s body temperature, but a can could be deliberately ruptured to create a thermal decoy.

 

[whulorigan]

If used to reduce thermal signature, a chill can is good for around four hours, during which time the user’s thermal signature is reduced almost to background levels. This imposes DM-4 on attempts to detect, track or target the individual using thermal sensors. By the end of the period the unit is saturated and thermal suppression is lost. The gel does not reach high temperatures; little more than the user’s body temperature, but a can could be deliberately ruptured to create a thermal decoy.

That's fine for a ~310K Human (+suit operation waste heat) in a ~280K - 300K surrounding background environment. A human in a suit (or a stealth-aerofighter) can blend into temperature variations and thermal inversions, but there is no such thing in deep space.

For a starship you need a "chill can/slug" that can reduce the signature to ~ 2.7K (or perhaps up to ~30K) from a 290K environment for simple onboard life support needs, let alone the waste temperatures generated by the equipment aboard (such as the fusion plant operation).

T5 has some of this type of technology in the section for heat dissipation with black globes, but I do not recall if says what the TL of the dissipation tech is (and I am too lazy to go look at the moment . . . ).

And the issue is that you need to reduce ALL signatures in ALL wavelengths across ALL spectra (including EM, gravitational, neutrino and other particle radiation, etc), otherwise detectors will be created to detect those signatures, if at all possible. And since space is one big giant open empty abyss, your signal does not generally get attenuated by distance due to intervening medium/media, and unless you are lucky enough to have something to hide behind as noted up-thread, it is also not overly likely to be blocked by an intervening body except by deliberate plan. Your signature is like a giant flashlight/electric-torch carried on a pitch-black moonless plain at 2am, or a 20-story-high football-field sized enclosed room with no internal lights and non-reflective walls. The farther you get from the source, the dimmer it is, but it is still obvious.

 

[Marcatlas]

If used to reduce thermal signature, a chill can is good for around four hours, during which time the user’s thermal signature is reduced almost to background levels. This imposes DM-4 on attempts to detect, track or target the individual using thermal sensors. By the end of the period the unit is saturated and thermal suppression is lost. The gel does not reach high temperatures; little more than the user’s body temperature, but a can could be deliberately ruptured to create a thermal decoy.

A chill can works in a non vacuum background of a very high temp compared to space. Not gonna work in space

 

[whulorigan]

I will quote someone else that had a similar tangential discussion on the Mongoose Boards in relation to the recently released MgT2: Starship Operators Manual. There the proposal was that the best possibility for the creation of stealth was via the gravitic interaction:

WHULorigan said:
The handwavium "proposal", to my understanding is either that:

• Waste heat is transferred off the ship via a process similar to the one used in the M-Drive Reaction with the local G-Field: The heat dissipator mutually interacts with the local gravitational field and spreads the heat via the gravitational interaction across other bodies in the system (which increase in temperature an infinitesimal amount relative to mass and distance, while the ship decreases in heat by an equivalent amount).
• Dissipation by conversion to direct gravitational radiation is also another related possibility (though this would theoretically be detectable by Grav-Sensors or GravComm, or possibly Densitometers).

Response:

I think it is likely to be a combination of both of those.

The coupling between the gravitics on a ship (grav plates, lifter, acceleration compensation, and the m-drive) will allow waste heat to be dumped into the body the ship's gravitics are coupled with, and this will necessitate gravitational radiation/waves.

And yes these could be detected, but here are the potential gaming benefits:
-stealth coatings and EM masking can now make ships very difficult to detect, the sub hunt becomes possible in setting
-gravitic sensors and neutrino sensors have a hard time picking the ship's signature gravitaional and neutrino emissions from the background
-a whole JTAS or companion article could be written to detail this (or referee's can make it up)
-battle damage, sabotage, or malfunction could affect the heat removal system so the crew must find a way to deal with the problem or be cooked inside their own ship

 

[kilemall]

Stealth was really the whole point of my going into all the EM spectra. So here are the conceptual rules for your perusal and dissection.

Each -1 DM for each stealth against a specific spectra costs 10% of the ship, new. So you could get a -4 DM built in for IR for instance for a 40% greater cost. This will work against long range IR array equipped ships, but not anything else.

Since I have 10-11 spectra and most ships don’t care about Acoustics, to get each -1 DM it costs the same as the ship itself.

Effective DMs need to get into the -3/-4 range, so for complete coverage the ships end up costing 4-5x as much.

So 90%+ of all stealth is applied only to small craft, for spec ops, smuggling and recon.

Repair costs scale the same and need specialized shipyard work at their TL.


The other usage case is knowing that a particular world or navy uses specific spectra for long range sensor or missile use. So it might be worth adding 60% cost to add 2 -3DM stealth coverage against a specific opponent.

Part of this whole subgame was to have situations like a stealth cutting corners with specific EM and not being detected by the enemy only to have some random Type L ship with oddball sensor fits easily spot them and broadcast hails.

 

[whartung]

I beg to differ - there is stealth in space. It's called hiding behind an object bigger than yourself.

It's not that there's no stealth in space.

Simply, there's no surprise in space.

Specifically, regardless of all of the assorted gee gaws used to hide, or lower signature, or anything else, they're all quite moot by the time you get close enough for anything to matter.

It's space. "Space is big." - D. Adams. You are always HOURS away from anything, anywhere.

You want deep space stealth on the edge of the solar system, fine.

You want to bury yourself into an asteroid field, wearing a parka and eating frozen PowerBars, be my guest.

But by the time you get close enough to anything for your firepower (and that's what matters here) to be effective, to ambush or pounce on something. Good luck with that. Remember, if you're in range, they are in range. You're not going to surprise a target enough for them to not be ready for you when you close.

At best the engagement starts closer than it perhaps would have without "stealth", but the simple truth is if they could outrun you at long range, they can outrun you at shorter range, and vice a versa. Whenever you get close enough to be threatening, their gunners will be in their stations, jacked up on coffee, waiting for you to get +1 closer for a 12 on 2D to matter. Then, they start firing. Laser ammo is cheap.

 

[Spinward Flow]

But by the time you get close enough to anything for your firepower (and that's what matters here) to be effective, to ambush or pounce on something. Good luck with that. Remember, if you're in range, they are in range. You're not going to surprise a target enough for them to not be ready for you when you close.

You're equating multiple sensor types and tasks together and assigning a difficulty of "automatic" to ALL of them collectively, regardless of context (or even tech level).

And yet ... we have real world examples of Terra getting "an extra (quasi)moon" for a while which no one knew about until being "discovered" by astronomers. My point being that even for "rocks in space" lacking in "stealth" features, it can potentially be a Hard Task™ to detect, let alone characterize such objects, even at relatively near (weapons range relevant) distances of 1-3 light seconds. Even once such objects are detected, they must be RE-detected in follow up observations to confirm their existence and begin to define their course plot (which may be "zero acceleration" inertial, but still).