Energy from heat - The argument against stealth in space

[phavoc]

A UK team recently was able to make a breakthrough in converting heat to energy. It's been possible for a time, but like many scientific endeavors, far from practical. The latest attempt had them using graphene with an exotic titanium mix. The new process now is able to handle temps from nearly room temperature to a few hundred degrees. The previous version had somewhere around 10 degrees or so variance.

It's still a far way off from being practical. So far they are only able to convert about 5% of the thermal energy into electricity. However that's much better than before so I'd say it was a success. It may be that in a few years or even decades they might be able to raise that percentage up. When solar power first came out it's conversion rate was quite low, but now it's far better.

So maybe finally the question of how do you hide a hot spaceship in the cold of space will be solved. Getting rid of power is easy.

 

[Anonymous]

If the heat was "pulled" from the surface of the ship, would the ship be cold to the touch? And if we are talking about projecting the technology into the future and the ship being effectively stealthy (in the infra red), would the surface of the ship be at or close to 0 degrees K? What other issues might this lead to?

Reaction drives obviously have a heat signature, does a gravitic drive have a signature?

I believe that today we can be identify vehicles (ships? aircraft?) by their exhaust signature, will that be true of a gravitic drive?

 

[Reynard]

Did everyone forget a trivial invention called 'ceramic heat tiles'?

Also remember Traveller has IR Chameleon (TL 12) and Vislight Chameleon (TL 13) technology for armor. I'm sure that's also the tech in ship Stealth coating. Even today our stealth fighters and bombers use a less advanced yet still effective stealth coating while engine exhaust is given minimum signature from detection but then do reactionless drives produce a detectable emission?

All relative and Traveller has done a decent job of extrapolation.

 

[phavoc]

If the heat was "pulled" from the surface of the ship, would the ship be cold to the touch? And if we are talking about projecting the technology into the future and the ship being effectively stealthy (in the infra red), would the surface of the ship be at or close to 0 degrees K? What other issues might this lead to?

I would assume with the strength of the hull materials the heat would be coming from within - the electronics, the people, the fusion reactor, etc. The hull itself shouldn't be generating much heat unless it was near a star. If you could convert heat to energy, it wouldn't be very hard to bleed some of that heat into the hull to make it the same temperature as your local space area.

Reaction drives obviously have a heat signature, does a gravitic drive have a signature?

I dunno, that's a good question. Off the top of my head I'd prolly say yeah, maybe a little, but not like a reaction drive. I would say that an A-G unit working against a planetary gravity field wouldn't necessarily though. In deep space there isn't any gravity field to twist or work against, so grav drives are probably slightly different in that respect than A-G in say an air-raft. That's just a guess though.

I believe that today we can be identify vehicles (ships? aircraft?) by their exhaust signature, will that be true of a gravitic drive?

I dunno. Maybe? I suppose that every ship would develop a personalized signature over time that with the right instrumentation you could 'fingerprint' it. Guess it depends on how you want to run that in your gaming universe. I don't see it as being beyond the realm of possibility though. Even for Trav!

Did everyone forget a trivial invention called 'ceramic heat tiles'?

Also remember Traveller has IR Chameleon (TL 12) and Vislight Chameleon (TL 13) technology for armor. I'm sure that's also the tech in ship Stealth coating. Even today our stealth fighters and bombers use a less advanced yet still effective stealth coating while engine exhaust is given minimum signature from detection but then do reactionless drives produce a detectable emission?

All relative and Traveller has done a decent job of extrapolation.

Nope, not at all. I've always been of the opinion that as the science of detection advances, the science of obfuscation is right behind it. Since we are talking about a gaming system that has fusion drives, anagathics, interstellar travel, etc, it shouldn't be a huge leap to think they'd figure something like this out. I posted the article summation because of the previous discussions that have occurred that said you can't stealth in space because you can't hide your IR signature.

I'm not sure of the relevance of ceramic heat tiles though. The issue has always been how will a space ship get rid of its internally generated heat? If you radiate it away through normal processes you will indeed light up like a christmas tree against very cheap and low-tech passive IR sensors. It's never been a question of can you make a 'cold' surface. Just what do you do with the heat you cannot stop from making?

 

[Reynard]

People seem to be under the impression a ship radiates any energy out in all directions. As I said about jet exhaust, it's masked and directed. If a starship need to hide then the systems would use internal venting to collect the worst energy sources and send them through directed sinks which seems to also be part of the Stealth option descriptor. Whatever that coating is, it works and it's good! Considering there are ships and systems above Stealth's TL 11, it seems there is no counter measure. It's real good!!

 

[Anonymous]

I would assume with the strength of the hull materials the heat would be coming from within - the electronics, the people, the fusion reactor, etc. The hull itself shouldn't be generating much heat unless it was near a star. If you could convert heat to energy, it wouldn't be very hard to bleed some of that heat into the hull to make it the same temperature as your local space area.

Yeah but. In order for your crew to not freeze to death the crew compartment (which on most Traveller deck plans is everything) is kept at "room temperature" which is something to the order of 300 degrees K warner than it is outside. The hull is therefore included in the "stuff that needs to be managed for stealth to be remotely possible" and is compounded by the heat generated by the stuff you mention, a fusion power plant? Yeah, that's gonna be toasty, some is shielded and some is bled off with whatever means the 57th century has come up with but if our sun is anything to go by (as it's the only fusion reaction that most of us have seen or would want to see) it is warm!

Reaction drives obviously have a heat signature, does a gravitic drive have a signature?

I dunno, that's a good question. Off the top of my head I'd prolly say yeah, maybe a little, but not like a reaction drive. I would say that an A-G unit working against a planetary gravity field wouldn't necessarily though. In deep space there isn't any gravity field to twist or work against, so grav drives are probably slightly different in that respect than A-G in say an air-raft. That's just a guess though.

It could be, if the heat signature has been dealt with as your OP speculates, that the passive sensors used in Traveller are actually looking for gravitic distortions. Sounds kinda logical to me! Densitometer anyone?

I believe that today we can be identify vehicles (ships? aircraft?) by their exhaust signature, will that be true of a gravitic drive?

I dunno. Maybe? I suppose that every ship would develop a personalized signature over time that with the right instrumentation you could 'fingerprint' it. Guess it depends on how you want to run that in your gaming universe. I don't see it as being beyond the realm of possibility though. Even for Trav!

Agreed. Maybe that's the difference that can explain the different sensors: basic military are good enough to ID a ship from it's gravitic signature. I may well have watched too many (bad) films but I'm pretty sure we can ID submarines from the noise generated by their propeller.

A lot of this is the kind of clarification I would love to see in the new version of Traveller that has not been announced yet and probably doesn't exist!!!

 

[Condottiere]

If you can recycle heat and turn it into energy, which turns back to heat in a closed system, I suspect you get a perpetual energy cycle, especially as the crew will certainly add to it.

As for propulsion, maybe the release of ions without generating heat.

 

[Anonymous]

Wouldn't an ion drive (if that's what you're suggesting) be a form of reaction drive?

How does one detect ions?

 

[ShawnDriscoll]

Ion means takes forever to move. Slow moving ships are seen way before their ions are.

 

[Condottiere]

The ship might have a fast enough velocity, the ion drive does some minor direction correction.

 

[phavoc]

People seem to be under the impression a ship radiates any energy out in all directions. As I said about jet exhaust, it's masked and directed. If a starship need to hide then the systems would use internal venting to collect the worst energy sources and send them through directed sinks which seems to also be part of the Stealth option descriptor. Whatever that coating is, it works and it's good! Considering there are ships and systems above Stealth's TL 11, it seems there is no counter measure. It's real good!!

Heat will go out in all directions unless you channel it through radiators (assuming no conversion issues here). Sure, you could have radiators that bleed out in a direction of 'behind' your starship, but once it leaves the radiator its going to spread out and dissipate like a gas would, thus you would generate a cloud of sorts behind the ship. And while it's cooling off it's changing the local temperature, thus it's showing up on IR as a temperature irregularity. If you exhaust heat as heat I don't know how you are supposed to contain it otherwise.

If you can recycle heat and turn it into energy, which turns back to heat in a closed system, I suspect you get a perpetual energy cycle, especially as the crew will certainly add to it.

As for propulsion, maybe the release of ions without generating heat.

In this instance excess energy could be converted into power and then beamed into space (through a laser, or even just as microwaves). I don't see it as a perpetual motion type of system because I don't think it would be enough to power the ship overall. We probably aren't talking megawatts (or gigawatts as a fusion reactor will probably be).

Yeah but. In order for your crew to not freeze to death the crew compartment (which on most Traveller deck plans is everything) is kept at "room temperature" which is something to the order of 300 degrees K warner than it is outside. The hull is therefore included in the "stuff that needs to be managed for stealth to be remotely possible" and is compounded by the heat generated by the stuff you mention, a fusion power plant? Yeah, that's gonna be toasty, some is shielded and some is bled off with whatever means the 57th century has come up with but if our sun is anything to go by (as it's the only fusion reaction that most of us have seen or would want to see) it is warm!

The hull itself, assuming there's insulation on the inside, would not generate or radiate heat externally. The heat would be trapped on the inside, thus it would build up to intolerable levels. The ISS has multiple cooling systems, with the primary being an ammonia-based one that picks up the heat from other cooing systems as well as the solar panels and then transfers the heat to a set of radiators to dump into space. You really don't want your hull to radiate your heat away like say your windows do in the winter, cause that means if your power fails you'll die from, well, from heat loss too. With no power on in a ship I don't know how much just humans would generate in heat. But with a well insulated hull then at least they wouldn't be losing any internal heat. I suppose one could calculate it if you wanted to. Bodies give off X amount of heat at rest, more when you are doing things, so that would tell you roughly how much energy a person is generating at any given moment.

 

[dragoner]

A UK team recently was able to make a breakthrough in converting heat to energy. It's been possible for a time, but like many scientific endeavors, far from practical. The latest attempt had them using graphene with an exotic titanium mix. The new process now is able to handle temps from nearly room temperature to a few hundred degrees. The previous version had somewhere around 10 degrees or so variance.

It's still a far way off from being practical. So far they are only able to convert about 5% of the thermal energy into electricity. However that's much better than before so I'd say it was a success. It may be that in a few years or even decades they might be able to raise that percentage up. When solar power first came out it's conversion rate was quite low, but now it's far better.

So maybe finally the question of how do you hide a hot spaceship in the cold of space will be solved. Getting rid of power is easy.

It is interesting for direct energy conversion, and how the power plants do their work, eg not by steam turbines or something.

The stealth argument has always been mooted by two factors: A ship's hull is going to be the ambient temp of that around it, otherwise it would mean it's permeable, and it can't be for what it resists, such as skimming, combat, hot zones such as nebulae, etc.. Second 95% of matter and energy being "dark", have stealth; so until there is further information, the argument is pointless. A lot of people take the term stealth to mean invisible, which isn't actually what it means anyway.

 

[Anonymous]

Direct energy conversion could also be stored in batteries to power systems as and when required.

 

[dragoner]

Direct energy conversion could also be stored in batteries to power systems as and when required.

As it stands now, how they actually do their work isn't described, but direct energy conversion seems logical. Capacitors might be better, with batteries for back up and things like starting.

 

[Anonymous]

And if we project this far enough into the future when batteries can discharge at rates approaching capacitors :mrgreen:

Unless of course I've misunderstood why capacitors would be a better choice over batteries?

Tho I guess I can stop quibbling over words and say "energy storage device with variable output rate" or some such

 

[-Daniel-]

Tho I guess I can stop quibbling over words and say "energy storage device with variable output rate" or some such

I love doing this when talking about fictional far future tech. Makes my head hurt less. :mrgreen:

 

[Anonymous]

Tho I guess I can stop quibbling over words and say "energy storage device with variable output rate" or some such

I love doing this when talking about fictional far future tech. Makes my head hurt less. :mrgreen:

See sig pic :wink:

 

[dragoner]

Tho I guess I can stop quibbling over words and say "energy storage device with variable output rate" or some such

Something, it's fine.

I love doing this when talking about fictional far future tech. Makes my head hurt less. :mrgreen:

Yeah, sort of like talking about air combat in the 1880's. :wink:

 

[Reynard]

"Heat will go out in all directions unless you channel it through radiators (assuming no conversion issues here). Sure, you could have radiators that bleed out in a direction of 'behind' your starship, but once it leaves the radiator its going to spread out and dissipate like a gas would, thus you would generate a cloud of sorts behind the ship."

Heat is IR energy which is part of the electromagnetic spectrum. This energy does not dissipate as matter does, it prefers to travel in straight lines until it hits an object that lets it bounce at angles. The only reason a ship would glow in all directions is energy, especially IR, is bleeding off in all directions and that's if the ship has little to no insulation. Space and starships are well insulated.

Remember the point of the fusion reactor is producing heat to be as efficiently converted to electricity as the technology allows. Very little waste heat. Marc Miller conceived that the modern fusion plant is a working cold fusion system so there would not be IR problems that can't be masked easily. The worst problem will be neutrinos.

The Traveller system's passive sensor mechanics take this all into consideration. Passive is the Is Someone There aspect of sensors. The Radar/Lidar is the Who Is There once you think you found something. The Stealth coat from the Core Book suppresses any leftover heat bleed normal insulation misses and absorbs the active energy directed at the ship so there's no return signal. The point from this is normal ships aren't concerned they can be spotted and there's still a chance they won't. That coating is expensive and noticeable. It's disadvantage is it screams I'm up to something so merchants don't bother with it to hide from pirates.

 

[Condottiere]

If you place enlarged cowls over the thrusters that both block view off heat radiating, absorb it and recycle it back into the ship.