JTAS sensor rules

[TheMachine]

But this leads me immediately to 2 follow-on questions -

1. How is the "ship systems" part of the power requirements divided up between the various components it encompasses?

We know from the 2e core rulebook that you can reduce this by powering down non-essential systems, like "the chicken soup dispenser on deck C", and this halves power requirements (that seems a bit high, but good for playability). Is this as far as we want to go with this? What about lighting? Probably not covered under "non-essential" but could also be powered down. What about heating? What about switching even oxygen processing off - just temporarily? Which brings me to...

2. How long would it take a ship with heating turned off to get dangerously cold, and how long could a crew survive on just the oxygen they have? Obviously this will depend on the ship (and, in the second case, the crew), but how could we calculate (or, rather, quickly guesstimate) it?

 

[AndrewW]

We know from the 2e core rulebook that you can reduce this by powering down non-essential systems, like "the chicken soup dispenser on deck C", and this halves power requirements (that seems a bit high, but good for playability). Is this as far as we want to go with this? What about lighting? Probably not covered under "non-essential" but could also be powered down. What about heating? What about switching even oxygen processing off - just temporarily? Which brings me to...

Doesn't have to eliminate lighting, just reduce it.

 

[TheMachine]

We know from the 2e core rulebook that you can reduce this by powering down non-essential systems, like "the chicken soup dispenser on deck C", and this halves power requirements (that seems a bit high, but good for playability). Is this as far as we want to go with this? What about lighting? Probably not covered under "non-essential" but could also be powered down. What about heating? What about switching even oxygen processing off - just temporarily? Which brings me to...

Doesn't have to eliminate lighting, just reduce it.

Well, to be honest, lighting is probably a tiny proportion of the total anyway. Something I missed out, that might be more significant, is the anti-grav plates.
But the broader question is - can they reduce ship systems power by more than half, and if so, what are the dangers/consequences?

 

[Linwood]

We know from the 2e core rulebook that you can reduce this by powering down non-essential systems, like "the chicken soup dispenser on deck C", and this halves power requirements (that seems a bit high, but good for playability). Is this as far as we want to go with this? What about lighting? Probably not covered under "non-essential" but could also be powered down. What about heating? What about switching even oxygen processing off - just temporarily? Which brings me to...

Doesn't have to eliminate lighting, just reduce it.

Well, to be honest, lighting is probably a tiny proportion of the total anyway. Something I missed out, that might be more significant, is the anti-grav plates.
But the broader question is - can they reduce ship systems power by more than half, and if so, what are the dangers/consequences?

Another thought - some systems do not take well to a quick emergency wakeup. Military-grade systems might act differently from civilian-grade systems.

Some of what we're discussing may already be part of 'standard' system architecture. For example, it's likely most ships have a 'night mode' that dims the lights in passenger areas. Cargo areas might be at reduced gravity in normal operation - why have full 1G in the cargo hold filled with crates and pallets of goods? Similarly, areas of the ship that aren't routinely manned might be allowed to go colder than normal. A crew might also elect to put everyone in vacc suits to run the environmental systems at even lower set points (I'm assuming they can plug into air supplies at their workstations to extend bottled air supplies).

I think I'd look at adding a negative DM to maintenance and repair checks for ships who routinely engage in extended power-down sequences, unless the ship has been designed specifically for that. Maybe a Routine or Average Difficulty skill check would be a way to avoid damage by bringing systems back up at the right pace and in the right order.

 

[AnotherDilbert]

I'm definitely pinching it for our game. In fact, I might add even more granularity at the low end (where players mostly live). Like so:

That is probably a good idea.

But beware large DMs on a 2D roll. Civilian sensors might become incapable of seeing small craft under basically any circumstances. Optimised military sensors already see nearly everything, we hardly need to make cruisers and battleships even easier to detect.

I would try to keep within ±2 under normal circumstances, and perhaps ±1 more under extraordinary circumstances.

So I would balance the increased granularity at the low end with less granularity at the high end, perhaps something like this:
-3: <___3 Power; missile?, perhaps a drifting launch?
-2: <__10 Power; small smallcraft under EMCON
-1: <__33 Power; small smallcraft, perhaps small ships under extreme EMCON
±0: <_100 Power; large smallcraft and small ships
+1: <1000 Power; medium ships, small military ships
+2: ≥1000 Power; large ships
+3: very large ships or stations.

Less elegant than a strict exponential scale, but perhaps more playable?


We should also check what happens with stealthed small craft, so they don't become undetectable...

 

[AnotherDilbert]

But this leads me immediately to 2 follow-on questions -

Current LED lighting takes next to no power on the Traveller scale. A small fraction of a Power point would light up a small ship like a christmas tree...

Unless the power plant is completely shut down, heating isn't a problem, cooling is the problem.


Starships lose heat rather slowly, direct sunlight can keep them fairly hot. In the inner system it's not a huge problem, unless you are in permanent shadow. In the outer system it's a problem.

 

[AnotherDilbert]

But the broader question is - can they reduce ship systems power by more than half, and if so, what are the dangers/consequences?

See "Not Enough Power, Cap’n!" sidebar, HG p16.

 

[Condottiere]

LED lightning is low hanging fruit, that the Vilani obviously never discovered.

Hence why one of the big Terran exports was RGB computer cases.

If I had to guess, the main power draw for hull tonnage was artificial gravity and inertial compensation, presumably followed by life support.

 

[phavoc]

Sensor rules are one of those things that has bedeviled all versions of Traveller.

For those who argue "there is no stealth in space because of XX", there is a legitimate counter using tech. Radar only works if the beam is returned back to the emitter (we have had stealth tech for decades at our current TL - it would be no different in the future).

Others counter the issue of heat - except none of the Traveller ship designs or the artwork in all of the editions feature the large radiator panels necessary to get rid of heat in space - which ironically is not that easy since vacuum makes for a poor conductor. 1960s tech had RTG's which convert heat generated from nuclear materials into electricity. Using room-temperature superconductors and more advanced materials makes it quite possible that 52nd century ships have mastered the tech required to convert heat to energy and thus you no longer have giant heat signatures in space.

Our history has shown us that for each vector of detection technology a counter is swiftly developed to off-set the sensor advantage. That concept should be alive and well in the future, thus making detection a reasonable issue (i.e. no magical detections at a bazillion meters distance). Which puts this concept back to the idea that is IS possible to have stealth in space - but not to the point where you have a 1,000,000 dton dreadnought sailing through an enemy formation because it's "stealthed". That is taking the silliness to the extreme. Which means some common sense and reasonableness needs to be applied. And, since this is Traveller, lots of arguments and rules lawyering is to be expected as well.

As far as the issue about detecting missile launches, that's a fair point. We don't even have an explanation of what sort of drives/engines a missile or torpedo has to move. Is it reaction-based? If so are we talking liquid fueled? Solid fueled? Both have strengths and weaknesses. Not to mention a hit on a missile turret can cause leaking rocket fuel if it's liquid. Or are the missile drives gravitic, like a ship, and have an internal capacitor that drives the missile for it's intended range? Some argue it won't matter, but others will ask their GM about this because it's important to them. And while the most common response is "it's whatever the people playing the game want it to be", that's a bit of a cop-out since you are buying a game system and are paying for others to have thought these things up and put them in the books you paid money for. Otherwise nobody should ever buy a gaming system but "just make it up as you go along" since that's the same applied logic. It will always be about finding a balance between useful minutiae and useless minutiae.

 

[Sigtrygg]

There is no legitimate real world technological answer to there is no stealth in space because there is no stealth in space without invoking magic technology.

Every energy transfer on the ship will eventually result in waste heat. You can not extract useful energy from waste heat, you have to get rid of it or it will cook the crew, scramble electronics, then melt the ship. The living area of the ship has to be maintained at 300ish K, insulate the ship so the insides are maintained at this temperature and the body heat of the crew will eventually contribute to cooking them without a refrigeration system to cool them, which requires... waste heat.

I don't have a problem with there being a gravitic or damper based magic heat sink in Traveller, but you think it would have got a mention by now.

 

[Ursus Maior]

You can not extract useful energy from waste heat [...].

The thermoelectric effect begs to differ. And advances into that field of research are being made: https://phys.org/news/2019-11-material-world-electricity.html

Yes, they are talking small scale electrics in that article. But this is not to say that most naval and ship-based electronics in Traveller wouldn't be small scale electronics by our definitions. And your definition of "useful" energy becomes very much dependent on technological capabilities, i. e. TL.

"Space magic" is very real, if you look from a TL 7 world into a future that is TL9 and beyond.

 

[AnotherDilbert]

It's not a matter of better engineering, it's a basic principle of physics; in short "entropy increases":
https://en.wikipedia.org/wiki/Second_law_of_thermodynamics


Yes, you can turn some not-quite-waste heat into electrical energy, but that means increasing entropy somewhere else, i.e. radiating more waste heat.


Like any other science it might be wrong, but it is well tested for centuries, so it's exceedingly unlikely.

 

[Sigtrygg]

You can not extract useful energy from waste heat [...].

The thermoelectric effect begs to differ. And advances into that field of research are being made: https://phys.org/news/2019-11-material-world-electricity.html

Ha I knew I would catch at least one. Just kidding.

Go and read this and do not believe everything you read in a popular science article written by journalists, better still is to understand the basic science behind it:
http://www.projectrho.com/public_html/rocket/thermodynamics.php

 

[Linwood]

I agree the energy from waste heat must go somewhere. I do wonder whether we will eventually find clever ways to slow that transfer rate down or to muffle the signature such that it is harder to detect against the background of space. That might indeed fall into the realm of magical technology.

We should probably also think in terms of broad- vs narrow-focused sensors. It's likely that stealthing past a narrowly-focused sensor system. But it's also likely that trying to search a wide swath to that level of detail would take a very significant amount of time. So being able to mute the IR signature such that broadly-focused sensors might miss the target would be of some use, even if they won't defeat a more narrowly focused sensor system.

Maybe the ultimate tech hack there would be to turn the waste heat energy back into matter. I figure that's at least a TL 16 innovation - definitely in the realm of magic!

 

[AndrewW]

Do a grandfather and create a pocket universe, dump the waste heat into there.

 

[Sigtrygg]

So every TL9+ society can create small pocket universes for heat management? :shock: :shock: :shock:

 

[AnotherDilbert]

I agree the energy from waste heat must go somewhere. I do wonder whether we will eventually find clever ways to slow that transfer rate down or to muffle the signature such that it is harder to detect against the background of space. That might indeed fall into the realm of magical technology.

We have to radiate waste heat, but necessarily equally in all directions.

I can imagine a system that can limit radiation in some directions and radiate more in some other directions. It would take advanced tech and energy, but it's not impossible...

 

[Sigtrygg]

That is a perfectly reasonable solution.

There are just a couple of counters to it - the first is having IR sensors scattered around your system, the second is that the directed radiated heat will interact with gas and dust in 'empty' space, said gas and dust will then re-radiate the heat in all directions such that a sufficiently sensitive passive IR sensor will notice this hot gas and dust...

 

[Condottiere]

I have no idea how a plasma carronade works.

So how about transferring the heat there until you turn hydrogen into plasma, and discharge it?

 

[Sigtrygg]

Your plasma cannon is 12kK, your waste heat reservoir is 300K - the heat goes from your plasma cannon into your waste heat reservoir and makes it even hotter and thus melts your ship faster.

A version of the second law of thermodynamics - heat can not go from cold to hot without external work being done.

So basically if you want to shunt waste heat from your ship into the plasma you will have to do work and therefore generate more heat than you transfer.