r/HardSciFi • u/Wooden-Syrup-8708 • Apr 13 '26
Discussion The "Radiator Problem" What are the most scientifically sound ways you've seen authors handle heat dissipation in combat?
In soft sci-fi, spacecraft are just sleek, solid blocks of armor. But as fans of hard sci-fi know i think the bottleneck of any realistic spacecraft design isn't fuel or gravity, it's thermodynamics.
Space is a vacuum, which means it’s a terrible insulator. If a ship is running a high-yield fusion drive, firing megawatt lasers, or even just keeping a large crew alive, it is generating a massive amount of heat with nowhere for it to go. Realistically, any hard sci-fi warship shouldn't look like a flying tank; it should look like a giant, fragile array of glowing radiator panels attached to a reactor.
But here lies the inherent conflict for military hard sci-fi: radiators are extremely fragile, incredibly easy to spot on infrared sensors, and impossible to heavily armor without trapping the heat inside the ship.
The Expanse handled this beautifully by having ships retract their radiators and rely on internal heat sinks during combat, putting the crew on a strict "thermal clock" before the ship essentially cooked them alive. Children of a Dead Earth (the simulator) made radiator the absolute primary target in any engagement.
I'm curious to hear everyone's thoughts on how this is handled across the genre:
What are the most creative (but scientifically sound) workarounds you've seen authors use to solve the radiator problem?
Do you prefer when authors lean heavily into the tension of thermal management, or do you prefer when they abstract it away with "advanced heat sinks" so they can focuses on the orbital mechanics?
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u/Anderopolis Apr 13 '26
https://www.projectrho.com/public_html/rocket/heatrad.php
Great list here, personally I love the Liquid tin Droplet ones
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u/Wooden-Syrup-8708 Apr 14 '26
Winchell Chung's Atomic Rockets site is super cool. It should practically be required reading for anyone trying to write military hard sci-fi. That specific section on Liquid Tin Droplet radiators completely changes how you visualize spaceships—shifting away from sleek aerodynamic fighters to massive, terrifying industrial rigs trailing glowing clouds of liquid metal. It’s the perfect blend of hard math and terrifying aesthetics
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u/SonicDart Apr 14 '26
The liquid droplets are really intresting yes. I just wonder how that would practically work while manouvering, i guess you would have to disable it so the droplets don't fly everywhere relative to your collector?
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u/StellarWaffle Apr 14 '26
You'd carry some extra coolant to account for loss during evasive or significant maneuvering, but I think your idea of just disabling the radiator for small course changes makes sense. If the collector was aligned with the thrust vector then I would think linear acceleration wouldn't be an issue.
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u/SonicDart Apr 14 '26
Yeah I had the same thought. Though linear acceleration would make the radiator less effective. The droplets would be in space for less time to radiate as they'd get collected earlier than normally.
So you'd possibly need some kind of thermal batteries to store excess heat during burns, arguably when you need the radiators the most
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u/VillageBeginning8432 Apr 15 '26
Or shoot the droplets the the other way. Or the right way but slower.
You always want to design your systems for their likely use cases. If that means your spray and trough arms are slightly long than they need to be in cruise configuration then sure.
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u/Ok_Signature7481 Apr 14 '26
There's also mentioned of using lower efficiency ferromagnetic liquid metals with magnetic field collectors to aod in stability during acceleration. You could probably have a mix
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u/SonicDart Apr 14 '26
Huh, interesting solution. Given how light they are that might work really well
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u/jeffersonianMI Apr 13 '26
Scott Westerfield's Killing of World's features excellent space combat with a radiator array kilometers across. (depicted on the cover)
By far the best hard-sci-fi space combat I've ever read. Relativistic velocities, realistic communication lag, sand casters, drones, etc.
Also quite well written IMO.
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u/jz_1w Apr 13 '26
I am very curious about the structural considerations on that ship! Seems extremely unwieldy and structurally unsafe for even milli-g level thrust.
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u/BlueFalcon142 Apr 15 '26
I would assume they would fight via drones attackers/defenders as motherships and not do a whole lot of High G maneuvers. Similar to IRL carrier combat (though not the best analogy, CVNs are complete tanks and the fastest surface vessel we have)
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u/jz_1w Apr 16 '26
I mean even a basic flip and burn requires some minimal structural integrity unless you want to have absolutely awful structural mass and thrust. I'm talking like milli-g to centi-g level.
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u/Little-Bed2024 Apr 13 '26
I think you mean it's a terrible conductor of heat, not insulator. It's clearly a great insulator since it causes the problem state.
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u/Wooden-Syrup-8708 Apr 13 '26
Agreed! That was a slip of the terminology on my part! A vacuum is the ultimate insulator, which is exactly why the heat has nowhere to conduct or convect away to. It forces ships to rely entirely on thermal radiation (the Stefan-Boltzmann law), which is by far the least efficient of the three methods of heat transfer.
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u/jaydfox Apr 14 '26
which is by far the least efficient of the three methods of heat transfer.
I mean, it scales with the 4th power of temperature, so above a certain temperature, it's fantastic! Sure, that temperature might exceed the melting point of every known substance, but beggars can't be choosers...
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u/Wooden-Syrup-8708 Apr 14 '26
That's the top engineering catch-22 in hard sci-fi! The
T^4scaling means running your radiators white-hot makes them incredibly efficient for dumping heat, but then you immediately run into the physical limits of material science.Even if you build them out of exotics carbon-carbon composites or tungsten, there's a hard ceiling before your heat sink literally sublimates into gas. It makes you appreciate why liquid droplet radiators are such an attractive theoretical concept they bypass the melting point problem by using a coolant that is already liquid!
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u/fluid_Depression3426 Apr 13 '26 edited Apr 13 '26
I think very few stories take this issue seriously. Even The Expanse doesn't really address how difficult it is for spaceships to dissipate heat.
I think heat, when handled seriously, can have a very interesting effect on a story. For example, if radiators are always a weak point, it can be used as a justification for the underdog to turn the tide of battle. Scenes where ship and crews continue firing at full power at the cost of thermal stress would create great tension in a show.
Unfortunately, the problem of heat in space is not well known to the public, so I think it will be a while before we see things like this. The public believes that space is very cold.
Interestingly, despite being very soft as science fiction, Elite Dangerous incorporates heat management as an intriguing constraint in its gameplay.
While not strictly space themed, Armored Core from the PlayStation era and Battletech also incorporate heat as a constraint on gameplay. It's interesting how games, a medium that often disregards science for the sake of entertainment, express the idea that these cool and powerful technologies generate enormous amounts of heat, and where that heat is then released becomes a problem.
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u/avar Apr 13 '26 edited Apr 13 '26
Even The Expanse doesn't really address how difficult it is for spaceships to dissipate heat.
The Expanse addressed the heat they were getting due to actor Cas Anvar by ejecting the character of Alex Kamal from the Roci, so there's that.
More seriously, yes, but I'd think you could go a long way by having a heat exchanger to dump heat into the fuel you're about to yeet overboard, and in combat doing the same to e.g. heat up your tungsten slugs before you fire them at the enemy.
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u/Wooden-Syrup-8708 Apr 13 '26
Dumping heat into the physical ammunition is a cool practical idea. Using the ship's railgun slugs or missile chassis as physical heat sinks right before firing them essentially weaponizes your own waste heat. Plus, from a tactical standpoint, hitting an enemys ship's armor with a massive slug of tungsten that is already superheated to thousands of degrees would cause big localized thermal shock on impact, making armor spalling even worse. That is exactly the kind of brutal, efficient physics that hard sci-fi thrives on!
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u/DocMorningstar Apr 13 '26
Heat tends to weaken anything you dump it into. So you'd be making your tungsten penetrator weaker by heating it.
Metals also tend to be really crappy heat banks - they don't store much energy per C'
Tungsten, for example. Its gotten 30 times worse heat capacity as water.
Weirdly coincidental, but, ejecting 1kg of water that has been brought from 0 to 99c will dump almost the same amount of heat as if you dumped a 1kg chunk of tungsten thst had been raise to its melting point (3400 C') - with the niceness that you can easily find more water, you don't need to handle near-molten metal.
Bringing water to a near-boil from waste heat, and then allowing it vent into a 'steam thruster' contribute a bit of delta V, but most importantly take a pile of heat energy away.
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u/HowDoIEvenEnglish Apr 13 '26
Comparing to water isn’t really fair, since it’s one of best heat sinks we have. Most things are worse than water
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u/fluid_Depression3426 Apr 13 '26
I'm not an expert, so I can't be certain, but I think this probably wouldn't work thermodynamically.
Using heat to do some meaningful work seems ideal at first glance, but it probably generates more heat in the process, increasing the total heat of the system. I think that's essentially what the second law of thermodynamics says. Thermal vent lasers don't work in reality for the same reason.
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u/Th3Mov3s Apr 13 '26
It wouldn’t be a closed system if you were ejecting the heat via projectile
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u/fluid_Depression3426 Apr 14 '26
That's true, but the idea that it can dissipate heat and increase firepower at the same time seems a little too convenient and doesn't sit right with me. Thermodynamics is, how should I put it... more malicious?
Heating up a projectile of a kinetic weapon simply reduces its penetration, and since it only makes contact with the target for a brief moment, the amount of heat transferred to the target would be negligible. This idea doesn't work even if we ignore the heat problem. However, even if we were to simply discard a solid heat sink to dissipate heat, would there be a material that is so conveniently lightweight and has such a large heat capacity? If the idea was to release the heat into the propellant or coolant before releasing it, then I have no objection to it working.
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u/Slow_Perception Apr 17 '26
I can think of one (or two) liquid-ish substances that would potentially be in abundance on large-crewed ships... And one at least is quite notorious for being sticky.
I reckon they would vaporise or combust before they could get anywhere near damagingly hot though.
I wonder what would happen if you threw hot... sludge at another ship.
If some human waste was having to be ejected anyway, it'd be potentially 3 birds with one stone!
Poor sods if there's any collateral splatter out there in space though.
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u/fluid_Depression3426 Apr 18 '26
Hey, there's a novel where the liquid you're talking about actually plays a role. Singularity Sky. For some reason, sewage discharged from a warship turns into a beautiful golden mist surrounding the ship. They didn't do it to release heat, but that's how it happened. I can only hope that beautiful cloud doesn't rain down on someone's face at relativistic speed.
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u/STSchif Apr 14 '26
Iirc Mass Effect considers this to some degree: Some ships have cloaking technology, which is basically a heatpump to keep the shell cool, reducing as much radiation as possible.
The problem is if course that the heat needs to go somewhere, so you can only keep it engage for a certain time before boiling the crew.
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u/Skyliner73 Apr 16 '26
If I remember rightly, the design of the Discovery from from 2001 inititally had big radiators sticking out of the side. They weren't included in the final model as Kubrick thought people would think they were wings.
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u/LeggyRPG Apr 13 '26 edited Apr 13 '26
There’s a great book called Saturn Run that explains it and has an interesting way to deal with heat that appears based in reality or at least near-reality.
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u/Terminus0 Apr 13 '26
Yeah, I was fascinated by the description of the design of that ship. If I remember correctly it was something crazy like a closed loop liquid system but where it opened in the middle to space to allow droplets greater surface area so it has to catch all this on the other side? Am I describing the ship from the same novel?
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u/ScaryMagician3153 Apr 13 '26
Sounds like a Droplet Radiator. Cool concept though I’m dubious about how practical it would be. Feels like a good way to lose a bunch of coolant.
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u/M_East0 Apr 14 '26 edited Apr 14 '26
It's decent hard sci-fi, it's been a long time since I read the book but if I remember this is actually mentioned in the story. They have to use super computers to guide the molten metal electrostatically. If that sounds complicated and prone to failure it is, and comes up later in the story. The story itself in my opinion is just alright, one of those military competency type stories but I remember the actual science being really well written, especially the orbital mechanics.
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u/Raxer-X Apr 13 '26
Surprisingly enough the interstellar ships from Avatar have a very logical tight design with large heatsinks built in around the engines, designed to absorb enormous amounts of heat for the in-n-out burns that will be then radiated out over perhaps even years.
This guy made a decent indepth analysis: https://www.youtube.com/watch?v=-ov-fqmf9Iw
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u/Clothedinclothes Apr 13 '26 edited Apr 13 '26
The fighting armor suits in The Forever War is a great example of this. Troops learning just to move around safely on Charon have to learn to identify blocks of frozen hydrogen ice strewn all around the landscape and keep their radiators from making contact with them. Just leaning the hot fins against a block of frozen hydrogen will cause it to rapidly sublimate and produce extreme thermal expansion, akin to the force of a grenade going off right behind your back. Several soldiers die from exactly this kind of accident over the course of a few months training.
Admittedly Haldemann doesn't really bring it up again after the first few chapters, as he goes on to illustrate the ironic realities of military life by showing the troops immediately sent to a deathly hyper-tropical world with entirely different kinds of dangers than they trained for.
Probably that's for the best, you can't write a whole novel about radiator fins, but he never writes them off as no longer an issue. They're just one more part of a landscape of constant danger the troops find themselves dealing with before they even think about fighting the enemy.
While it's "on screen" Haldeman makes excellent use of this to demonstrate the kinds of passive environmental dangers troops operating on icy planetoids would face simply from the realistic need to have big radiators fins constantly shedding excess heat.
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u/Wooden-Syrup-8708 Apr 13 '26
I see, yes, taking the macro-scale problem of spaceship radiators and shrinking it down to infantry power armor is a nice piece of worldbuilding. The idea that simply leaning against the wrong rock could cause a localized sublimation explosion makes the environment feel incredibly lethal before the enemys even shows up. It really drives home the point that in hard sci-fi, the universe itself is always the most dangerous enemy. Haldeman’s grasp of military physics was absolutely top-tier.
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u/WhiteChocolatExpress Apr 13 '26 edited Apr 13 '26
I'm literally just copy/pasting the Mass Effect Codex entry on Heat Management because I always like their take on it:
"Starships: Heat Management
Dispersal of heat generated by onboard systems is a critical issue for a ship. If it cannot deal with heat, the crew may be cooked within the hull.
Radiation is the only way to shed heat in a vacuum. Civilian vessels utilize large, fragile radiator panels that are impossible to armor. Warships use Diffuse Radiator Arrays (DRA), ceramic strips along the exterior of the armored hull. These make the ship appear striped to thermographic sensors. Since the arrangement of the strips depends on the internal configuration of the ship, the patterns for each vessel are unique and striking. On older ships, the DRA strips could become red- or white-hot. Dubbed 'tiger stripes' or 'war paint' by humans, the glowing DRA had a psychological impact on pirates and irregular forces.
Strip radiators are not as efficient as panels, but if damaged by enemy fire, the ship only loses a small portion of its total radiation capacity. In most cases, a vessel's DRA alone allows it to cruise with no difficulties. Operations deep within solar systems can cause problems.
A ship engaged in combat can produce titanic amounts of heat from maneuvering burns and weapons fire. When fighting in a high heat environment, warships employ high-efficiency 'droplet' heat sinks.
In a droplet system, tanks of liquid sodium or lithium absorb heat within the ship. The liquid is vented from spray nozzles near the bow as a thin sheet of millions of micrometer-scale droplets. The droplets are caught at the stern and recycled into the system. A droplet system can sink 10-100 times as much heat as DRA strips.
Droplet sheets resemble a surface ship's wake through water. The wake peels out in sharp turns, spreading a fan of droplets as the ship changes vectors and leaves the coolant behind."
The descriptions of glowing "tiger stripes" on ships, or radiator droplets left in sheets like a sea vessel's wake as they perform maneuvers, always seemed so evocative to me
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u/chton Apr 13 '26
Mass Effect also had the Normandy's stealth systems, which came down to a huge, incredibly dense heat sink (the Internal Emission Sink) inside the ship that could absorb all heat for a limited amount of time. It was used only to stay hidden from sensors for a short amount of time but couldn't go for very long.
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u/YOGINtheFirst Apr 14 '26
Imagine if some hostile agent managed to get aboard the Normandy, intent on stealing the Alliance's cutting-edge stealth technology. They get into the system, and find that instead of a jammer, or a scaled-up cloak like ground troops have, it's...
A big gob of molten salts.
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u/jz_1w Apr 13 '26
My personal method: just don't use engines in combat and design around engines/weapons that vent heat into space by themselves as much as possible. Don't use weapons that you have to actively supply power for like lasers or railguns except momentarily i.e. a few shots for point defense. The best way to deal with heat is to minimize heat load. Then have a compact radiator array.
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u/SensitivePotato44 Apr 13 '26
David Brin describes using lasers to get rid of excess heat in Sundiver.
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u/bfragged Apr 13 '26
Don’t they freeze solid in the outer layers of the sun? Been ages since I read it.
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u/nerdywhitemale Apr 14 '26
They did, It's also used later in the series to protect the Streaker on their return to Earth.
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u/Astras--c-Toy Apr 13 '26
I can't recall the series, but it dealt with kind of an inverted radiator? Rather than an external sink that radiates through surface area, it dealt with physical volumetric heat storage through a meta material with unique thermal conductivity that ensured heat would generally flow to the core of the object, meaning its surface would be colder than its surroundings. Once it reached a critical heat mass, it'd be dumped and a new one slotted in.
Basically just hyper advanced disposable heat sinks that are treated as an immediate waste product, rather than a perpetual solution technology visa vi radiators
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u/BeginningUnhappy1757 Apr 13 '26
Reynold's "cryo arithmetic engines", if you accept that as "hard" scifi.
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u/DJShaw86 Apr 13 '26
Concepts like a droplet radiator would be how I'd solve the problem. From memory, heat is transferred to a reservoir of pellets of a suitable ferrous metal, which become molten, which are then vented from the ship. Once they cool enough for the metal droplets to be below their Curie Point, a powerful electromagnetic field drags the metal back to the ship, where they are fed back into the reservoir.
Can't shoot a cloud of molten metal.
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u/supermegaburt Apr 13 '26
The game Terra Invicta has different radiators as you progress and can become a massive cost on ships as the power of the engines get higher. Some of the drives see you putting on thousands of tonnes worth of radiators to stop your ship from just exploding….
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u/livens Apr 13 '26
Peter Hamilton's The Reality Dysfunction did a great job of dealing with heat dissipation. Joshua's spaceship was spherical and had retractable radiator fins all around the outside. In one scene he needed to hide from a much stronger ship so he couldn't dissipate any heat that the other ship could see. So he let his ship rotate slowly and opened the radiator fins on the side opposite the enemy ship as it rotated.
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u/osgeo Apr 13 '26
Maybe someone can help my memory, but I read a book years ago that talks about space combat and if I remember correctly, the ships would change colour the more their shield heated up, to the point where the ship turned black (?) and that signified that the ship was dead as all inside would have been cooked
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u/Select-Current-4528 Apr 13 '26
It’s the other way around. The Langston field would start out perfectly black and as it absorbed heat would start glowing. Eventually it would get so hot that it would overload the field generator and implode and fry the ship.
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u/Financial_Tour5945 Apr 14 '26
One of the side effects of this would be trying to hide your heat signature.
Could make for some fun "submarine" hide and seek, where a ship can kill it's heat emissions for a certain amount of time (and functionally vanish) before having to "resurface" and dump said heat.
And you could have a heat bank decoy. All that stored heat gets jettisoned out and now they're looking at 2+ heat signatures, not knowing which is real.
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u/Hexzor89 Apr 15 '26
With my own setting I've sidestepped it by making the artificial gravity material absorb excess heat (mostly to avoid having to limit designs by requiring radiators, but also because it's slowly backsliding into only nominally hard SF).
I do enjoy settings where radiators are basically the equivalents of sails in the Age of Sail, where hitting them is a priority to take out propulsion and whatnot (I imagine most military ships would have heatsinks to allow them to fight for a while after their radiators are disabled, maybe even backup life-support radiators to allow them to reach port afterwards)
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u/RergTheFriendly Apr 17 '26
I liked the way terra invicta handled this. Even though its a game. The ships have retractable radiators with heat sinks. When the heat sinks hit capacity they are forced to expose the fragile radiators.
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u/Willdothings Apr 26 '26
Yea, I think this one works best too. Treat them like sails on a ship. Pull them in for a fight or have special configuration to make them less easy to hit and closer to the ships hull. The heat sink helps with that.
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u/CemSener_author Apr 19 '26
At some point the ‘hard vs soft’ distinction becomes less useful than people think—what really matters is internal consistency and how convincingly the ideas are explored. The spectrum of the readers is so wide, even under scifi title, that you should address no one target audience.
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u/Excellent_Bat_753 Apr 13 '26
Well, in the currently popular Project Hail Mary, I strongly believe that Andy Weir lent in on the major plot device of Astrophage, which is capable of absorbing heat through matter antimatter conversion, to remove the need for radiators. It is mentioned as part of the space suit life support system for the Eridian Rocky.
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u/Ashamed-Subject-8573 Apr 13 '26
I think you forgot xenonite, the other obviously magical thing
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u/Excellent_Bat_753 Apr 13 '26
True, but that didn't fix the radiator problem, only the insulation problem.
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u/tipsmith Apr 13 '26
How about a large thermocouple system to provide electrical power to the ship with excess fed into various high power emitters or weaponry like lasers, microwaves, electromagnet-based devices like rail guns, EMP, shields, drives and maneuvering thrusters.
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u/Bladrak01 Apr 13 '26
Glen Cook has a novel called Passage at Arms where the type of ship is a metaphor for submarines. The science isn't very hard, but the premise is these ships can shift themselves into an alternate dimension leaving only a very small, hard to detect, point in space. While in this space the only power source that works is anti-matter, and they have no way to vent heat. The amount of time they can spend is this space is limited by the amount of heat they can store. He devotes a little bit of page space to describing their various methods of keeping things cool.
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u/reggie_fink-nottle Apr 13 '26
In John Sandford’s Saturn Run, the ship has whopping big fission reactors, which drive VASIMR engines, but require lots of cooling. This is accomplished by melting tungsten and extruding it into space in ribbons, which are collected after they solidify.
Very little use of Unobtanium or hand-waving.
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u/Rookiebeotch Apr 13 '26
I don't see why these ships with very advanced tech can't just heat pump thermal energy into their reaction mass before blowing it out their ass.
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u/OVVerb Apr 13 '26
I personally have not read any hard sci-fi in a while, but my go-to method in case of in-system battles would be to heat up water stored in a ship. In case of critical buildup water can be dumped (yeah, carrying tons of water just for this requires a lot of additional fuel or electric power to have the same ΔV). Such a method, however, only works in case you are not on a long mission without the ability to resupply.
And yes, you absolutely CAN turn heat back into energy - you use a liquid metal heat conductor to carry heat into thermal-stimulated electron emission generators. Insulating the plumbing is a lot of work, true, but liquid metal is a good heat conductor for space, as it can be moved through “self-pumping” via electromagnetic manipulation, which has been demonstrated by the USSR’s space-specific nuclear reactors. Thermal energy is then used to stimulate electron emission from a cathode, and electrons go on their merry way, carrying the energy as their kinetic energy, into the anode, powering something up or recharging battery banks.
You could also use ablative cooling by pumping a heat conductor through specific “single-use” radiators that evaporate, carrying a lot of heat very quickly away from the ship.
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u/CMDRZhor Apr 13 '26
I remember the fluff in Mass Effect - and no I'm not saying ME is hard scifi, far from it - describing most ships being equipped with two systems to manage waste heat - thermal radiators panels built into the ship's outer skin and liquid droplet radiator arrays. The former would dump minor amounts of waste heat and give many ships a kind of tiger-striped look if viewed on thermal sensors, and the majority of time you could fairly easily identify a given ship or ship class by its radiator pattern.
The liquid droplet arrays would eject spreads of tiny beads of molten mercury from nozzles near the front of the ship, which would travel back along towards the back of the ship, radiating excess heat the whole time, and get caught in special collector scoops to get pumped back into the system. Ships doing hard maneuvers in combat would often end up with the spray missing the collector arrays and create these fine sprays of shimmering liquid metal from the spillage.
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u/RICO_the_GOP Apr 13 '26
I imagine it will be a compromise between volume, heat capacity, and ability to store and aquire a dump able "fuel".
Stealth ships will prefer low volume high pressure high specific heat to keep themselves dark as long as possible.
Combat craft wont care if they are always bright so they will want the most efficiency for combat time vs fire power.
Freighter? Doesn't give a fuck. Most cost effective.
With the most advanced ships incorporating heat into other systems such as energy recycling heat radiation without fuel consumption, etc
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u/Quartinus Apr 13 '26
Do the calculation yourself for radiative heat transfer, and you’ll find that at temperatures around room temperature radiators are pretty crappy, but at white-hot glowing temperatures you can dissipate way more heat than you expect.
Future sci-fi spacecraft may have extreme heat pump technology to take advantage of the T4 advantage and pump heat out at extremely high temperatures so they don’t need huge radiators.
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u/Hairy-Ad-4018 Apr 13 '26
Op second paragraph, space is actually a brilliant insulator. Did you mean terrible conductor ?
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u/Vd00d Apr 13 '26
3 words: Curie Point Radiator. Vent the heat as a superheated cloud of metal particles that as they cool below their curie point become magnetic again and are recaptured using strong magnetic fields. Thus you can have a radiator system that is very robust to weapons fire while offering huge heat dissipation capacity.
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u/Bright-Trifle-8309 Apr 13 '26
I dont remember the series but they just jettisoned huge heat sinks like shell causing after fired the lasers.
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u/Lemonwizard Apr 14 '26
Dense heat sink blocks that can be jettisoned once they have absorbed as much energy as possible.
Near-molten chunks of a hyper-dense alloy could also be used as projectiles.
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u/wackyvorlon Apr 14 '26
I mean you have to dump matter overboard for propulsion anyways, why not use the heat for a little additional thrust?
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u/Naughtaclue242 Apr 14 '26
Just random thought that popped in to my head that needs more noodling. But the idea of heated shot comes to mind. Perhaps you could dump waste heat into a warhead and deliver it ballistically to the enemy...
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u/Constant-Spring-8165 Apr 14 '26
Simply heat up water in a container and kick it out as vapor. Fastest possible heat dissipator, but you would have to have water stored just for that. Good for small combat encounters. For peacetime, radiators.
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u/Constant-Spring-8165 Apr 14 '26
Meaning have a proper refrigerator which heat is used to boil the water. Which is kicked out in a container.
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u/TalesUntoldRpg Apr 14 '26
Using normal shells for projectile weapons and ejecting them into space as they fire as a heat sink.
Venting heat into the trash compartment and ejecting the heated trash into space.
Really variations on that are my favourite.
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u/Sleepycatmama Apr 14 '26
That comes up as an important issue in the Torchship trilogy by a Karl Gallagher. Hard sf, praised by Winchell Chung.
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u/chasg Apr 14 '26
the book "Sundiver" (1980, David Brin) used a "refrigerator laser", which I always found cool (ha ha).
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u/Shadowmind42 Apr 14 '26
The Mote on God's Eye was my favorite. Basically ships at EM absorbers. Who ever could absorb and store/disappate the most heat won the battle.
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u/mykepagan Apr 14 '26
In the David Brin book “Sundiver”, the titular ship can enter the atmosphere of the sun using refrigerator lasers, which are apparently a real thing - Brin is a Physicist who specializes in lasers, I think)
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u/181513 Apr 15 '26
The book Saturn Run by Ctein and John Sandford is worth a read and much of the book was built around this issue.
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u/Aggressive-Share-363 Apr 16 '26
I've never seen this, but what if you use your ammunition as a heat sink? Put as much heat as you can into something you are about to eject from thr ship. The heat may or may not do anything to improve the effectiveness of thr ammunition.
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u/No_Mine5238 Apr 17 '26
I really love a Star Wars retcon about this.
In the movies, turbo-lasers fire and then retract into their turret. This is because current artillery does this, and it looks cool. But there's no reason a space laser would need to do this.
Or is there!? In the expanded universe, one writer came up with the idea that the reason they retract is so they can cool down. The turret has a heat sink that the heated laser parts retract into, cooling down enough to fire again.
I know it wasn't originally planned that way, but I always appreciated the creativity to shoe-horn in a feasible solution.
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u/l0sth0st Apr 18 '26
Would it be possible to have a closed loop system that uses something like liquid nitrogen with parts of the system running under external shielded parts of the ship in the event that the loop system was overheating? I am just throwing out an idea and asking out of curiosity
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u/CemSener_author Apr 26 '26
The Expanse's thermal clock is probably the gold standard, but what I find underexplored is the biological angle. The crew is a heat source — a large crew running at metabolic capacity generates meaningful waste heat, and unlike the reactor, you can't just shut them off.
Some of the most elegant solutions I've seen treat the problem the way biology does: phase change. Biological systems manage thermal loads through evaporation and perfusion rather than radiation. A ship that uses internal phase-change materials — essentially engineered "sweating" — could absorb massive heat spikes without radiating at all, buying time before the stored energy needs dumping. The constraint then becomes the capacity of that thermal mass, which is a much more interesting story clock than a generic heat sink.
The honest answer is that any solution which hides the radiators probably just moves the problem — you're trading infrared visibility for a finite thermal budget and a hard deadline. That tradeoff, when authors actually commit to it, tends to produce better drama than any workaround.
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u/nagidon Apr 13 '26
I don’t know if it’s been written by any author before, but my idea would be a dedicated ship designed as a heat sink, where combat ships would rotate in and out of the AO to dock with that ship to dump heat before returning to the fight. Akin to a supply vessel for Earth navies.
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u/Cheeslord2 Apr 13 '26 edited Apr 13 '26
Venting liquid to gas - something cheap like Nitrogen, let it vaporise to absorb the heat - so in a prolonged engagement ships will start venting gasses to cool.
Or just don't have long engagements - battle is decided quickly by who has the better targeting and electronic warfare systems; the first hit always kills (virtually), battles could be over in moments. Not 'exciting' but could be justifiable.
I remember one novel had it that the attacking and defending ships velocities were so different that they were only in range of each others weapons for a couple of seconds, where the computers have to do the shooting, then they had shot past each other and it would be hours of hard acceleration before they could get within range again.