OTU Only: Stealth and Detection in the OTU

[Supplement Four]

Just FYI...I wrote some simple Sensor Rules for Classic Traveller. The basic mechanic is easy. You roll 1D, 2D, or 3D, looking for your ship's computer model number or less for a lock. Modifiers apply. The number of dice you throw is based on range to the bogey.

S4's Special Supplement Four: Sensors.

 

[atpollard]

1. Traveller has "naval warfare" style space combat (ref: design notes from Battle Rider). Thus we have "sub hunts".

2. TRAVELLER has Stealth in space. Not just the OTU, but any setting which defaults to the core rules.

3. "HOW is stealth possible?" is not the question that people ask. They ask "HOW can we avoid fantasy?" Wil's note about "magic melt-resistant radiators".

4. You can't avoid fantasy.

Perhaps we can't avoid fantasy ... we already have fantasy MD and fantasy JD because 'reality' is just so much less fun.

Before I throw in the towel, let me attack the fantasy argument from the other direction. I think that we are overestimating detection optics. What is a reasonable minimum detection size? How many seconds of arc for 1 pixel and what size is that at various ranges?

I have a vague recollection that the wavelenth being detected has an absolute maximum resolution.

Can I really spot a match in the OORT Cloud from LEO?
Why can't we see the moons on worlds around other stars?

So in Traveller, at what distance can I really spot a missile travelling straight at me? I suspect that it is not infinite.

So what happens when there is a star a few hundred parsecs behind that missile? When does the IR pixel detect the missile and when does it detect the star?

 

[mike wightman]

How can one interpret "maintaining complete silence" in CT Book 2 except that Stealth in Space is possible in the OTU?

Define complete silence for me please. For one thing remaining quiet in space is a non issue, so they are obviously using the phrase to mean something else. It is my contention that 'maintaining silence' means powering everything down and minimising heat signature by directing you' waste heat magi-exhaust' (TM) away from the observer.

This makes it difficult for the passive sensors to find you until the relatively short range of 0.25 light seconds with civilian sensors or 1 light second with military sensors.

I also maintain that this isn't really detection in the sense that you first notice something, it is detection in the sense that you can obtain a weapon lock

To continue to argue that there is no stealth in the OTU and ships can 'see' everything within a parsec is pointless unless you can provide something from the actual game that at least suggests that is the case, because the sensor and detection rules seem to clearly indicate a different reality for the OTU.

It is a weapon lock range, not detection range, despite the language used by the authors.

If you delve into the Alien modules you find CT rules for using the sensors at parsec ranges to detect gas giants and planets, if you can do that you can find a ship with in a few AU no problem.

I suggest, absent any evidence from the rules that sensors are all-seeing, that the real question is not IF there is stealth in the OTU, but HOW it might be done.

See Mayday, High Guard etc.
LBB2 'detection' means 'obtain firing solution'.

 

[mike wightman]

Just FYI...I wrote some simple Sensor Rules for Classic Traveller. The basic mechanic is easy. You roll 1D, 2D, or 3D, looking for your ship's computer model number or less for a lock. Modifiers apply. The number of dice you throw is based on range to the bogey.

S4's Special Supplement Four: Sensors.

Mine are better, they are based on Star Cruiser

Ok, I do like yours too

 

[mike wightman]

1. Traveller has "naval warfare" style space combat (ref: design notes from Battle Rider). Thus we have "sub hunts".

Both Brilliant Lances and Battle Rider sensor rules are based on the lessons learned from T2300 Star Cruiser, which is a much more elegant system.

2. TRAVELLER has Stealth in space. Not just the OTU, but any setting which defaults to the core rules.

No it doesn't. See my earlier posts on 'detection' really meaning 'obtain firing solution'.

3. "HOW is stealth possible?" is not the question that people ask. They ask "HOW can we avoid fantasy?" (ref: Wil's note about "magic melt-resistant radiators". He didn't ask how it was possible: he already knew that it was only possible via fantasy.)

Lots of handwavium based on unobtaininum.
Gravitics and damper technology could be used to come up with an in-setting pseudo-science.
Basically the entire enclosed hull of the ship is cooled by the same acceleration compensators and artificial gravity fields that perform all the other magic. This requires a lot of energy which is obtained from the waste heat that would normally need to be radiated into space.
If your gravitics and acceleration compensators fail, then not only do you start to get thrown around as you maneuver but you also start to cook.

4. You can't avoid fantasy.

You can if you have science fictional explanation rather than a 'it just so happens that' explanation.

Traveller has several magical technologies, as you move away from the world of real physics then you are in danger of fantasy rather than science. If the magic technologies are rationally explained, coherent and not too full of plot holes and laws of unintended consequence then you can make it work.

 

[mike wightman]

Perhaps we can't avoid fantasy ... we already have fantasy MD and fantasy JD because 'reality' is just so much less fun.

And damper technology, and gravitics, and meson technology (whatever that really is) and black globes...

People have long described Traveller as hard science because it has shotguns in space etc. and many of the early adventures take place on low TL worlds that are described not unlike shanty towns or the wild west here on earth (something Firefly/Serenity tapped into).

BUT

There is a science fantasy setting hidden in plain sight. Once you are at TL8 in CT you have fusion power, air/rafts, man portable laser weapons - you are not in Kansas anymore.

TL9 brings absurdly cheap travel around a solar system, not to mention the ability to travel to adjacent systems.

This could turn into a rant ...

As long as we have a pseudo-science to describe the changes that come as TL advances (and the new toys in T5 make the TL15 Imperium more potentially transhumanist than it has ever been - at long last) then it remains science fiction.

And don't throw in the towel this is a really useful discussion.

 

[robject]

Once you are at TL8 in CT you have fusion power, air/rafts, man portable laser weapons - you are not in Kansas anymore.

In a nutshell, that was what I intended to imply with the "fantasy" label. I didn't mean dragons and magic... however, Clarke's Law applies.

 

[mike wightman]

In a nutshell, that was what I intended to imply with the "fantasy" label. I didn't mean dragons and magic... however, Clarke's Law applies.

Clarke's law shouldn't apply until TL21 and higher...

reason being that the TL of CT generated planets can hit 20

 

[atpollard]

Define complete silence for me please. For one thing remaining quiet in space is a non issue, so they are obviously using the phrase to mean something else. It is my contention that 'maintaining silence' means powering everything down and minimising heat signature by directing you' waste heat magi-exhaust' (TM) away from the observer.

This makes it difficult for the passive sensors to find you until the relatively short range of 0.25 light seconds with civilian sensors or 1 light second with military sensors.

I also maintain that this isn't really detection in the sense that you first notice something, it is detection in the sense that you can obtain a weapon lock

It is a weapon lock range, not detection range, despite the language used by the authors.

If you delve into the Alien modules you find CT rules for using the sensors at parsec ranges to detect gas giants and planets, if you can do that you can find a ship with in a few AU no problem.



See Mayday, High Guard etc.
LBB2 'detection' means 'obtain firing solution'.

No argument from me on 'complete silence' being a more poetic than literal choice of words.

Your argument that 'detection' = 'firing solution' is internally self-consistent (I grant that much) but has the problem of being a very strange definition of 'detection' as that word is commonly used and carries the paradox that I must get close enough to 'detect' (firing solution) a ship before any ship can track it at much longer range (per the rules as written).

I believe that the simpler common definition of 'detect' (to spot) fits better into the CT LBB2 rules. (and the T5 sensor rules describe active measures to 'hide'). Most of the thermodynamic arguments render any form of 'hiding' impossible, and that is clearly not what is presented. Taken as a whole, the CT rules create a very sub-hunt feel. Changing that dynamic is the core of many other arguments (like piracy) so it seems important to accurately paint the OTU with the correct basic technology assumptions.


The Planetary Detection is a logical fallacy. We can detect binary stars at staggering distances, but cannot image any planets outside our star system and are constantly finding new comets in our solar system. Gas giants may be detected by gravitational effect and the MD may prevent gravitational detection of a ship under acceleration. The ship may take efforts to avoid detection (like 'complete silence' ) that the planet and gas giant do not.


High Guard is admittedly an abstracted combat system. You would surely not argue that a fleet of dreadnoughts is incapable of invading a world defended by one fighter because HG says they cannot shoot the fighter, so they cannot break the defensive line of battle to attack the world. It seems more silent on the issue of detection than coming down for either strong or weak ship detection.


Mayday likewise seemed to present no sensor rules, but at least it was clearly not an abstracted combat system. So I do conciser Mayday as evidence that strong sensors are plausible. I am, however, uncomfortable using the lack of sensor rules in Mayday as proof that all ships can see everything in the system with no detection check required rendering stealth, spy ships and piracy all impossible in the OTU. I would really like to find something affirmative, some rule that states or clearly implies broad, long range detection of starships.

 

[whartung]

Just to clarify, how is "stealth" defined. Detection that SOMETHING is out there, detection that a SHIP is out there, detecting that a SCOUT SHIP is out there, and/or acquiring weapons lock on the SCOUT SHIP that is out there.

Those to me seem to be the 4 levels of stealth.

Which levels are we talking about here?

 

[aramis]

Just to clarify, how is "stealth" defined. Detection that SOMETHING is out there, detection that a SHIP is out there, detecting that a SCOUT SHIP is out there, and/or acquiring weapons lock on the SCOUT SHIP that is out there.

Those to me seem to be the 4 levels of stealth.

Which levels are we talking about here?

Weapons lock should not be longer than identification.

• To detect that it's a blip - active or passive, 1 pixel minimum.
• To detect that it's moving - active or passive, 1 pixel and 3 fixes over time†
• That it's a ship - active or passive, 1 pixel, and 4 fixes showing an acceleration curve inconsistent with other known items
• To get a firing solution - at least 2 passives* or 1 active sensor, at least 1 pixel, and at least 3 fixes over time.
• To ID the size: bigger than 1 pixel and distance known. (a single pixel only sets a maximum size; a known range, resolution angle, and size >1 pixel gives both a minimum and maximum size). Active sensor improves data by giving more accurate distance, and if >1 pixel, albedo in sensor's frequency, as distance can be measured by time, area by pixels, and albedo by return energy per pixel.
• To ID the hull type: at least 16 pixels across and known range. Active again gives more data.
• To ID the class: observation over time, including acceleration, gravity interactions, change in return shape, albedo, RF signature, temperature, and neutrino output...

*2 passives only gives 2D, but axial rotation can create multiple axises and thus 3D. Technically, one off center can do this, too, but probably not effectively enough for combat rangefinding. But since we only need range, that can be done on 2D passive, and the angle to it determined by which pixel(s) of the field of view of the passive are triggered. A 3rd passive not only increases range finding accuracy, but also positional accuracy, tho'. Oh, and the wider the baseline, the more sensitive the rangefinding.
† 3 fixes are needed to determine speed reliably; 2 can do it but 3 is about the minimum for use. Or so I read in an old coastal artillery manual... 3 fixes with the binocular rangefinder.

 

[SanDragon]

As an alternative to the automatic "radiate lots of always-detectable heat in all directions always" that some seem to insist on, what is wrong with hull insulation, heat pumps/hull&drive-cooling systems, and using the lasers/other energy weapon to discharge the excess energy (heat converted to electricity) in the opposite direction from whatever you are trying to hide from?

As long as you aren't in a dust cloud, there will be nothing to scatter the energy in the beam, and thus the beam won't be detectable from any appreciable distance unless it later bounces off an object or hits a dust cloud.

Well, unless you're willing to wait for passive information as to where the thing you're hiding from is at, you won't know where to bleed the excess heat to.

And I doubt anyone would want to bleed heat off in jump space in order to equal the local 3 Kelvin temperature when you fall out of jump space until you do know.

~~~~~~~~~~~~~~~~~~

Oh, look. A little late to the game. Not unusual.

I'm thinking stealth in this case is the ability (or not) of a ship to appear to be something it isn't.

Forgive my falling back to MT, but the sensors provide first, scan (there's something out there) and then pinpoint (there it is!), which is provided in as few dice rolls as possible (not going there).

Your success in identifying something is dependent on how well you rolled and what size and/or energy signature it has.

Success, exceptional success, small, large, low, high. (I'm shotgunning, I'm too lazy to dig up my manual.)

Ships can also reduce power plant output so as to appear smaller than they may actually be, and adding stealth technology helps them appear 'smaller' than they actually are by reducing the signature of their power plant.

But then, we can wrench the whole thing with the 'military' technology of the expensive densitometer and/or neutrino sensor.

Egad! I think I just came out of the closet as a grognard, due to the crunchiness of MT!!! XD

 

[Patron Zero]

Sidebar if I may.....

Are there any canon materials concerning the launching of counter-measures to decoy-deflect an active search for a ship 'running' silent ?

Obversely, does said searching vessels have deployable ordnance to enhance efforts to find 'concealed targets ?

 

[mike wightman]

In CT no.

In the Traveller corpus then yes.

TNE (FF&S, BL and BR) had the benefit of being able to draw from T2300 sensor rules (which do what you ask too) and MT.

 

[kilemall]

Just to clarify, how is "stealth" defined. Detection that SOMETHING is out there, detection that a SHIP is out there, detecting that a SCOUT SHIP is out there, and/or acquiring weapons lock on the SCOUT SHIP that is out there.

Those to me seem to be the 4 levels of stealth.

Which levels are we talking about here?

MgT has an explicit process, ranges and equipment levels for detecting, typing, and firing.

CT just describes detection without any distinction for fire control or typing (the -5 DM for switching targets does suggest a certain lead time to build a firing solution).

HG leaves detection open too except for the BGG rules which explain that turning the field on in detection range means you can't maneuver and the enemy has a virtual firing solution since they had your last vector.

Can't speak to the other systems.