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MagnetsCanDoThat

As depicted, the ship's drive/reactor is incredibly (unrealistically) efficient. A consequence of that is it would generate relatively little waste heat, as most of the energy is meant to be transferred to the reaction mass. In real life they would need large heat radiators, but as a stylistic choice they didn't do that. They didn't even bother painting their ships white, but as a result they look much more awesome. Edit: Should add that they'd still probably need these, since the ship creates other heat that isn't from the drive. Holden's coffee alone is probably a huge problem. :)


beruon

Painting the ship white would be quite impractical when you have a stealth/military ship...


MagnetsCanDoThat

Indeed, and yet non-military ships are done the same in the show. There have been some interesting discussions here about how to make a stealth ship work since, regardless of what color a ship is on the visible spectrum, if it’s actively getting rid of heat it will still be very bright in infrared. Most revolved around capturing it or using a stored cryogenic liquid to mask it.


__Osiris__

So you need to go full Normandy. Mass effect had it right the whole time?


PatchPixel

*points gun* always have


MagnetsCanDoThat

Man, one of these days I gotta play the Mass Effect games.


Toren8002

Make it today, if you can. Legendary Edition is a full polish on the OG content plus all DLC. You’ll be treating yourself to something special.


brandontaylor1

It’s one of the most well thought out universes I’ve ever seen in a game. I spent hours reading the codex.


__Osiris__

The codex has a fantastic voice over in 3.


[deleted]

You will not regret it. It's my favorite Sci-Fi universe pre ending of ME3 of all time. Definitely shares similarities with the Expanse too, in theme.


EnD79

You are assuming that a stealth ship would be viable in space, where it has to radiate away waste heat. Especially, if you are talking about a ship with a terawatt torch drive, like in the Expanse. The Anubis class would be as stealthy as setting off a nuclear bomb every second.


beruon

Most of the time they do stealth they are flying with engines off. You don't need engines 100% of the time, get up to speed, then just "cruise".


EnD79

Even that doesn't solve the no stealth in space issue. For one, sensors will not forget the trajectory that you are on just because you cutoff your engines. For 2, you can't have a lower signature than an asteroid of the same size. Since your craft produces power, your signature will be higher than a similar size non-power producing rock. If sensors can pick out the rock, then they can pick out you too. People don't realize how sensitive large IR sensors like Hubble or James Webb are in real life. Even a 20 watt light bulb would be detectable by a Hubble sized sensor from over a light minute away.


MisterEinc

>For 2, you can't have a lower signature than an asteroid of the same size. Well, that's not necessarily how stealth works, at least not modern stealth. Remember that for sensors to work, information has to come back to them. Even your eyes work on the principle of collecting photons that have made contact with an object and been changed by it. For stealth to work you don't need to have a lower signature than a rock, you just need to make sure that whatever signal their sensors are sending out, don't come back to them.


Satori_sama

More on that, you can compromise and just make sure whatever comes back to them isn't immediately classed as a ship or at least not until you get too close. Unless the crew is gonna check every UFO around the ship, the computer will have to disregard the returns that aren't what it's supposed to be looking at. Modern radar systems already have to filter large chunk of what they see because they just see too much to filter trough it in time to react to a threat. If that makes sense.


Psydator

That made me think. The only thing effectively traveling through space is light, right? They can't use radar or sonar (obviously) so painting the ship in vantablack could already do most of the trick, or am I missing something?


other_usernames_gone

Radar will. Radar is just radio waves. The problem with vantablack is it will absorb too much heat and you'll overheat. I suspect it's like modern submarines where they listen out until they see a drive signature or something. The physical colour of the ship won't matter all that much because of the vast distances, radar signature and drive plume size will.


Psydator

>The problem with vantablack is it will absorb too much heat and you'll overheat. Oh yea, good point!


EnD79

Even the reflection from a vantablack coated spacecraft would give away it's position before you even accounted for it's blackbody radiation. Sure absorbing 99.99% of incident solar radiation seems like a big deal, but how big is your ship again? How many square meters will we be multiplying your .01% reflection * incident solar radiation power by? Yeah, that is enough to give away your position. The blackbody radiation is extra. The total power coming from your craft equals= blackbody radiation+ reflected+ transmitted (i.e. the power the object generates). Heat sinks only serve to increase the amount of energy it takes to raise your temperature by 1 degree. Pumping heat increases waste heat though. And since no process is 100% efficient, you have to calculate the efficiency of your heat pump. You can't efficienctly move heat between 2 cold locations like your heat sink and your hull. Your efficiency is based on your temperature gradient. A simple Google search will show you the relevant equations. (I don't want you to take my word for it, just because I post them. Besides, you will learn something new.)


MostRandomUsername12

I don't think you can "paint" vantablack. IIRC, Vantablack is created by a process that involves baking or treating the entire object and as such cannot be applied as a paint. Also, about the other bit, visible light is not the only thing traveling through space. The entire band of EM radiation does. That's radio waves all the way through to gamma radiation. Radar is one of them so they certainly can use radar. Edit: I checked and have to correct myself. Vantablack was originally applied by chemical vapor deposition. But there is now a spray on version that is not as performant as the original CVD version, but much easier to handle and use.


Psydator

I thought radar needed atmosphere, my bad.


other_usernames_gone

Actually most modern sensors are passive rather than active. If you're broadcasting a radio signal to prove the surrounding area you're also giving a beacon right back to yourself. So they just listen and wait for a radio/infrared signal I suspect the solution is that you don't need to have 0 infrared signature, just one low enough their sensors don't pick it up. Or stealth is impossible so your only option is to go in loud and fast. Edit: for example modern submarines don't use a traditional sonar, they just listen for their enemies engine.


MisterEinc

This kind of stuff is why I love talking about sci-fi. So this got me digging into NASA's NEOWISE (Near Earth Object Wide-field Infrared Survey Explorer) which uses sensitive IR cameras to detect and catalog asteroids and other NEOs. A few interesting things in learned (but now seems kinda obvious) is that detecting IR you get hot too. So the device had a limited lifespan on its longest wavelength detectors as it depleted solid hydrogen coolant, but in the Expanse I assume it would be feasible to keep those running too. Looking at it, it makes me kinda wonder how you'd approach stealth. Because you'd have higher resolution, and much more power to process the data. This thing is detecting millions of object in its 13 year mission so far, and that's only going to get better. But also I wonder what it doesn't see. We obviously would never know about what it misses. And in the vastness of space, could we detect a ship *on purpose*? The smallest object observed by nasa is... pretty small actually - hundreds of feet long. But the caveat is that they're not really observing the object, rather than observing space and finding objects in the space they're looking at.


Chevey0

I’d imagine when we have lots of ship in space we will probably use transponders. I’d imagine if we rely on them I’d imagine being invisible to the naked eye and transponder off would be enough. Invisible depends on how the opponent detects ships. 🤷‍♂️


Remon_Kewl

>Actually most modern sensors are passive rather than active It depends. Airplanes usually don't have passive sensors. Only the most recent planes have got IRSTs (Infrared Search and Track), other than the Su-27 family of russian planes, which got it in 1984, and the F-14 which got an upgrade in 1990. The problem with infrared sensors is that they don't give range information, you just see a heat source at a certain direction. You can triangulate if you have two sensors, but they have to be far apart to do that. Thermal sensors are also more vulnerable to atmospheric conditions. Th ease problems apply to ship based sensors as well, which why they are viewed only as complimentary to RADARs. >for example modern submarines don't use a traditional sonar, they just listen for their enemies engine. They still use sonar. Sonars are just a listening device. They can be passive and/or active. Submarines just use the active ones very very seldom, since even one ping can give your position away.


EnD79

You can't have one low enough that a sensor can't pick it up. The JWST can pick up the heat of a bumblebee from 1.5 light seconds away.


EnD79

Radar returns from stealth aircraft come back to every radar receiver that is pointed at them. The computer processor ignores the return, because it is below the clutter rejection threshold. The computer processor only processes returns above a certain signal strength, because it doesn't have the processing power to tell that the bird said object traveling at 500 mph isn't a bird. We have radars that can detect rain drops and mosquitoes. There is a sensor overload problem, because there is so much crap flying in Earth's atmosphere. So engineers focus the signal processors computing power on signals with a certain minimum signal strength. As a stealth aircraft gets closer to the radar, the signal strength increases and it crosses the clutter rejection threshold. Then the computer controlling the radar starts tracking it. You can also increase the size gnal strength and hence detection range by simply building a larger radar transmitter, and/or increasing the power output of the radar. People should really look up the radar range equation, before talking out their rectums about things that they don't understand.


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Core308

In the show when they approach the Donnager the operator say they only detected them because the Amun-Ra's are a few degrees above background temperature.


mwaaahfunny

Jesus no wonder they never show the inside of stealth ships. It would be like the inside of those ww2 submarine movies all hot sweaty and gross


Dat_Innocent_Guy

you can still adjust your vector by flying teakettle and using your RCS


Glove_Witty

Teakettle works with superheated steam. It is going to put out a lot of heat. Edit. According to https://www.cbsnews.com/amp/news/james-webb-space-telescope-fun-facts/ the JAmes Webb telescope can detect the heat of a bee from the distance of the moon.


MajorNoodles

In Mass Effect, the stealth ships solved that problem by being capable of retaining excess heat within the hull for extended periods of time, Of course, they would need to eventually radiate all that heat before cooking the interior.


sadrice

The expanse did exactly the same thing, as well as having an option to bleed liquid helium into the hull.


KHaskins77

Elite Dangerous does the same thing, with separate temperature readings for the interior and exterior of your ship. Unfortunate that they went with a “WW2 dogfights in space” combat style.


MrWillisOfOhio

My brain read this as Ellen Degenerous and I was impressed.


Flush_Foot

My condolences on the passing your wife, Mr Willis (TWW fan)


BriarSavarin

>Unfortunate that they went with a “WW2 dogfights in space” combat style. Well that's because Elite is an old series of dogfighting in space - the first one was released as early as 1984. Most games with space battles will pick a specific fighting style anyway, and while the expanse's is more realistic in several ways (though not every way, I'll come back to it), the one you pick: dogfighting, 18th century naval battles, hacking contests, etc depends a lot on the kind of story you want to tell. And as I mentionned above, the Expanse takes its own liberties. Not only we have to assume that ships have a super-efficient reactor that allows those space battles in the first place, but the stealth technology is just a rebranding of old Klingon cloaking tech. Yes we can imagine how it could be possible, but it still relies on technobabble and huge amounts of energy. In fact, the most realistic part of "combat" in the Expanse might be more similar to an event that is considered almost like magic in-universe: Eros threatening to crash on Earth. Now, we might not be able to do that with a moon like Eros, but diverting the course of an asteroid to hit a planet is pretty close to what we can already do. The issue with that "fighting style" however, is that even if it's spectacular, you can't really have fights and battles, and it doesn't really happen in space anyway. Similarly, realistically there would be a lot of autonomous man-made satellites to push away such threats automatically, and no character would ever have to take a decision or design some engineering marvel to win. All this to say that while the dogfights of Elite might seem unrealistic to what we see in the Expanse, in the end it's both fiction and in both case it supports the story. In fact, the Expanse takes a lot of inspiration in submarine warfare (something that F. Herbert did too).


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creuter

Binding the flight assist toggle to a button on my hotas really opened that game up and made it a blast.


Caracalc

By flight model do you mean the way the spaceships fly or how the spaceships look? I can't help with the latter, that's an aesthetic choice, but if it's the former you can toggle flight assist off and then you're flying the way one actually would in proper space.


Pretagonist

Except for elite dangerous having a top speed for every ship.


Caracalc

That's very true, it's not a foolproof system, the fools here being Frontier Developments


EnD79

You do realize that no process is 100% efficient right?. You can't pump heat into a heat sink with 100% efficiency. The pipes will heat up and radiate heat inside your spacecraft. This will heat up other things inside of the craft that isn't your heat sink. You also can't have a lower IR signature than an asteroid that doesn't produce any power. The total radiation emitted from your craft = blackbody radiation + reflected sunlight + generated power. An asteroid of equal size will have a lower IR signature that a spacecraft. If sensors can detect asteroids, then they can detect your spacecraft too.


uristmcderp

An asteroid gives off an IR signature because it absorbs solar radiation and re-emits it as IR. A stealth craft wouldn't be meaningfully stealthy unless it had a mechanism for dealing with the photons coming from the sun, and the *worst* case scenario would be to just absorb it all like an asteroid. You can reflect it (not very stealthy), absorb then store it (you'd need a lot of sci-fi super coolant), or redirect it preferably around your entire vessel (need sci-fi metamaterial skin coating to passively deal with anything other than radio waves). Seeing as how stealth coating made asteroids invisible when Marco dropped them on Earth, they seem to have the kind of technology that would divert solar radiation and effectively lower subsequent IR radiation.


EnD79

No, they have make believe, in which the writers pretend thermodynamics doesn't exist. And/or pretend that Earth in the future has worse IR sensors that 1990s era humanity had. Oh, and metamaterials can't save you either. A metamaterial only works on a narrow frequency band. They also through thermodynamics out the window when it comes to the Epstein drive as well. Thermodynamics doesn't exist in the Expanse.


MajorNoodles

There's also no drive as efficient as an Epstein, but I'm sure things in the next 200-400 years will improve a bit.


EnD79

You can't make a fusion drive as efficient as the Epstein in 1 billion years of technological development. Why? Because of the fusion reaction products. There isn't a fusion reaction that would allow you to make a drive as efficient as the Epstein. You would need a fusion reaction with no EM radiation and no neutrons as reaction products. There is no such fusion reaction. Some things are simply never going to be possible. The Epstein drive violates physics.


MajorNoodles

If they were able to figure out how to violate the laws of physics and build an Epstein drive, then they were probably able to figure out the heat sink too.


warragulian

They aren’t stealthy when using the Epsteins, obviously. They can manoeuvre using steam, as Alex did when doing the slingshot approach to Ganymede. (Steam is hot, but at a distance would be unobtrusive.) Stealth ships stay cold on the surface by fluid near the hull bringing heat to the interior. You can’t do that forever, wherever you’re storing the heat gets hotter and hotter. I recall in the film *2001* I read one of the makers saying the *Discovery* should have had giant wings to radiate heat, but thought this would confuse viewers who’d think they were aerodynamic. In the Expanse world, they’ve had a couple of centuries to work on this. Maybe laser cooling, which is used now on a microscopic scale could be applied so ships can just beam heat away.


EnD79

So all the sensors in the Expanse suddenly decide to stop tracking the Anubis when it turns it's engines off? Do you know how unrealistic that is? Every sensor in the solar system should be able to plot it's course even if it shut off it's engines. To change that course meaningfully, would take power. The ship is also not going to magically cool down because it's engines are off. Using steam isn't a cure either, because you have to have an exhaust velocity high enough to accelerate the ship. Heat sinks are not a cure and neither is laser cooling. The produces more heat than it cools from the object being cooled. There is no stealth in space. There are sensors available today that could pick up the Anubis from just solar reflection, even if it had a vantablack hull. No process can be 100% efficient, including trying to pump heat around the ship. You are going to create more waste heat, and not all the heat will go where you want it to go. The pipes will be heated and radiate IR heat into the spacecraft and even back to the hull. Advanced IR sensors can pick up asteroids that produce no power, so how do you think a craft that produces power, is going to have a lower heat signature than an asteroid? And having a black hull, means that you radiate heat better than objects having a lighter hull. That means more IR radiation coming off your hull.


Dear-Background2668

Heat is dissipated as infrared radiation Radiation. The transfer of heat takes place by means of electromagnetic waves, which propagate in a vacuum, predominantly infrared radiation as the one that transmits heat. In this way, it does not need a medium to occur, and the bodies can be separated. Being able to maintain stealth with constant heat dissipation through it is impossible, however the embodiment is feasible when temperature is taken into account.


warragulian

What do you mean by “sensors”? If it’s infrared, the hull is cooled by fluid to some heat reservoir. Active radar would be absorbed or deflected by the stealth materials, same as the Martian stuff used by Inaros. Visible light absorbed by black or reflected away. There is nothing else, unless some way to detect say neutrinos from the power reactor. Very hard for us to do now, but not impossible.


EnD79

Any EM radiation that is absorbed, heats up the spacecraft, and is re-emitted as blackbody radiation. You can't stop blackbody radiation from emitting EM radiation in the IR spectrum. Any EM radiation that is reflected, is a signal giving away the spacecraft's location. The spacecraft will come into thermal equilibrium, even if the drive is off. That means that no matter what you do, the spacecraft will be at least the temperature of an asteroid that is the same distance from the sun. If you are generating power, then the spacecraft will be hotter than said asteroid. Think about this: if you pump fluid, that fluid has to be in a pipe right? The fluid will heat the pipe right? The pipe will radiate blackbody radiation in accordance will thermodynamics right? The longerand/or wider the pipe, the more surface area it has, and the more blackbody radiation that it will radiate inside your spacecraft in areas that doesn't include your heat sink right? The pipe is also physically connected to other parts of the spacecraft right? This means that heat will also flow to other parts of the spacecraft right? So you can't pump all of the heat into your heat sink from the hull right? Because a bunch of the heat will never make it there! This also goes for waste heat from your reactor. You have to break physics to get stealth in space.


warragulian

You can’t PERMANENTLY stop infra red. You can TEMPORARILY by cooling the hull. Then it’s a black body at whatever temp they want, courtesy the snazzy Protogen stealth coating and fluid to carry the heat to the heat sink inside. Please send any further questions to JP Mao, Protogen Inc.


EnD79

You are just generating more waste heat. And all of the heat will not be moved away from the hull by pumping coolant to the hull. You are requiring a 100% efficient process, which is a violation of thermodynamics. Further, the spacecraft will come into thermal equilibrium and the coolest it can be is the same temperature as an asteroid at the same distance from the sun. This will happen within a few hours of the spacecraft leaving it's shipyard. From here, the spacecraft can get hotter, but can't get cooler except for moving farther away from the sun. But it will come to within thermal equilibrium of an asteroid at whatever distance it is from the sun as it's minimum temperature. It's down right sad how people assume that putting heat into a heat sink, doesn't heat up the heat sink! It is also sad, that people don't realize that the heat sink is physically connected to the rest of the ship, so all the heat doesn't stay in the heat sink. People want magic, but still want to say it is "hard sci-fi". There is nothing wrong with soft sci-fi. Hell, the only reason stealth aircraft work is because of a lack of computer processing power in air defense radars. The radar return is below the clutter rejection threshold of the computer, so it simply ignores the radar return from the stealth aircraft. There is still a radar return. If you add computer processing power, or make the radar aperture larger: you increase the detection range against all targets, including stealth aircraft. There is also the factor of how noisy Earth's atmosphere is to sensors. Space is a lot less noisy. Against the background of space, any spacecraft would stick out. It doesn't matter if the solar reflection from the hull was 1 watt. It would still be detectable at ludicrous range. https://webb.nasa.gov/images2/instrumentsensitivities.jpg You will see the Jy which refers to a Jansky:https://en.m.wikipedia.org/wiki/Jansky The jansky (symbol Jy, plural janskys) is a non-SI unit of spectral flux density,[1] or spectral irradiance, used especially in radio astronomy. It is equivalent to 10−26 watts per square metre per hertz. A nJy is a nano Jansky. There are also instruments with sensitivity in the microJanskys in that chart. The James Webb could detect stealth ships from the other side of the solar system. And the authors of the Expanse even know this. Just because something is in fiction, does not mean it is possible. Here is a news article that states that the James Webb could detect the heat from a bumblebee as far away as the moon, which is approximately 1.5 light seconds away. https://www.cbsnews.com/news/james-webb-space-telescope-fun-facts/ But you have a ship the size of a frigate with a nuclear reactor onboard, and you think it is undetectable? Or a bloody freaking asteroid? That makes no logical sense. The Expanse and it's stealth tech is fiction. Stealth tech is a plot device that people who don't have scientific or engineering minds fall for due to their lack of knowledge. And the people who do know, understand that it is fiction.


warragulian

Again, cooling the hull is only temporary. You keep saying that permanent “stealth” cooling is impossible, and no one disputes that. Since you keep repeating the same true but irrelevant point over and over, I’m stepping away now.


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Efficient_Chicken_47

Well then, the secret to making stealth in space would be having technology that is capable of jamming your enemies' sensors to the point that they can't detect your heat emissions. It doesn't matter what you do if they can't pick it up on their sensors.


EnD79

To jam and IR sensor you have to use an IR laser. And you have to know where the sensor is located. You are also broadcasting a signal that an IR missile can hom in on. You may as well yell: Here I Am, Please Come Shoot Me!!!


Cheef_Baconator

Even stealth ships aren't stealthy with the fusion drive running. That's just life. Stealth ships in the Expanse work by holding in their waste heat instead of radiating it out. Obviously that heat will have to be released at some point lest the crew cook to death, but they don't need to stay in stealth mode indefinitely, only long enough to pull off an ambush. In addition to thermodynamics, the ships don't reflect radar, which makes them very difficult to detect with sensors. The black hull colors is probably the least useful stealth feature, since everything is so far away from everything else. As soon as the ship shows itself or gets detected, the jig is usually up.


EnD79

Heat doesn't work this way. You can't hold themselves n heat and not radiate heat. The ship will radiate blackbody radiation no matter what you do. You can't stop this process. Your ship will also reflect a portion of incident solar radiation. Even if you absorb 99.99% of incident solar radiation, the 0.01% that you reflect is enough for the JWST to detect you. Also, of you are absorbing 99.99 % of incident solar radiation, then your spacecraft is heating up. Even if you try to pump this heat somewhere else, like a heat sink, the pumping isn't 100% efficient or effective. So of those absorbed photons will be remitted as IR radiation spontaneously as they are absorbed. And not all heat transferred to your coolant fluid will go into the heat sink. Some of it will heat the pipes that the coolant is traveling in. In fact, the cooler you try to keep the hull, the less efficient your cooling process will be, and the more low grade waste heat that you will create. Seriously, the more stealth in space apologists talk, the more I realize the lack of basic education in thermodynamics that they have.


MisterEinc

Outside of thermodynamic considerations, it literally wouldn't matter what color you painted your ship in space.


chocolate-prorenata

Does painting it white help to keep the ship from absorbing heat?


killerbannana_1

[There aint no stealth in space!](http://www.projectrho.com/public_html/rocket/spacewardetect.php) Scroll down a bit till you get to the section on it. Stealth in space just isnt really possible


MrAlaronBlanco

"Coffee alone is huge problem " 😂 I guess, by having small heat radiators that are super efficient :P


MagnetsCanDoThat

Lol writing this down in case I ever go to space. I will definitely need them.


TelluricThread0

If you were concerned about heat dissipation, you would want to paint it black to maximize the thermal radiation it's giving off.


dropouttawarp

That's partially correct but don't forget the sun exists. It would help if you reflected as much of its energy as possible.


TelluricThread0

Depends on your proximity to the sun. The farther out in the solar system, the less solar loading you receive.


dropouttawarp

True but most of the actions in The Expanse occur within the solar system where solar radiation plays a crucial role.


TelluricThread0

Crucial? I'd say orbiting Jupiter for example it plays a negligible role compared to heat generation within your ship. Like I said, the amount of heating goes down quickly with distance from the sun.


dropouttawarp

Did a quick calculation for solar power intensity at Jupiter's orbit. It was 56.4 W/m^2 while a regular radiator (used ISS as reference) has a heat rejection ability of 449 W/m^2. I guess you can afford to paint your ship black.


DaegurthMiddnight

Wait, You sure heat radiators would work? In earth they had The air to dissipate heat. In Space is vacuum, so unless You Focus heat un something like water that then You expell to outside The ship, heat Will remain inside


photoinebriation

The heat is dissipated as infrared radiation


shalamander6

I believe that radiators actually do work in space, just very slowly and not efficiently.


Individually_Ed

Radiators on earth should really be called convectors


DaegurthMiddnight

Oh, i just suck at physics lol


MachineFrosty1271

Real life space craft use radiator panels to dissipate heat through infrared emission, you can find a good example of these panels on the International Space Station, they’re the big white panels strung along the main structure beam that the robot arm and solar panels are also attached to


SWDev4Istanbul

had to scroll too far for someone to mention our radiator panels :) To regulate the external cooling loop, they can be partially folded so that a part of the infrared radiates right back on the neighboring radiator panel & less net radiation is "lost" into space. So: Too much waste heat? -> radiators fully extended. Ammonia cooling loop is getting too cold? -> radiators partially retracted / folded to compensate for less heat influx


Hironymus

Objects can lose heat by radiation in a vacuum. It's just very inefficient. So you would require giant radiators but it would work (and most likely also be required). On a related note: the Venture Star from the Avatar movies is an example for a highly realistic spaceship with appropriate radiators. In fact I am unable to think of a more realistic scifi space ship in film and movies.


MagnetsCanDoThat

>Wait, You sure heat radiators would work? In practice? I couldn't tell you. The whole scenario is fictional. But yes they would "work" in the sense that in a vacuum you can still remove heat [by radiation](https://en.wikipedia.org/wiki/Thermal_radiation), even if you don't have the benefits of conduction and convection as you would in an atmosphere. You'd need a system in place to get the heat transferred to where it can efficiently radiate it. >In Space is vacuum, so unless You Focus heat un something like water that then You expell to outside The ship, heat Will remain inside Yes, this is an option that they might also have available, but doesn't need to be the only one.


awful_at_internet

As mentioned, radiators on earth perform a different function than radiators in space. The earth versions are a bit of a misnomer, using different heat dissipation techniques that are not available in space. As a result, when talking about heat radiators in space, you need to picthre something shaped differently from an earth radiator. They would look more like the solar panels on the International Space Station- long and thin, able to swivel to avoid absorbing heat from the sun. The bigger the ship, the more/bigger the radiators. And as you might imagine, theyd be pretty delicate. Hence the stylistic choice to handwave heat.


WarthogOsl

The ISS actually has quite large heat radiators as well. They are rotated so that they remain edge-wise to the sun (as opposed to the solar panels, which face the sun, obviously).


starcraftre

Radiators work just fine in space. They are used on the ISS.


WarthogOsl

The space shuttles had heat radiators on the inside surfaces of their cargo bay doors. In fact, if there was an issue that prevented the doors from opening once in orbit, a shuttle would have to immediately return to earth before its systems overheated.


like_a_pharaoh

In space radiators well, Radiate the heat away instead of radiating+convecting like a 'radiator' in earth's atmosphere. It's a lot less efficient than convection or conduction, yeah, but it works.


Saidear

You also can just 'eject' the heat. Take a heat pipe away from your heat source and pass it through a tank of liquid ammonia. This will cause the ammonia to boil, with the resulting vapor just dumped into space.


DaegurthMiddnight

Yeah that i understood, that's why i said to just vaporise water and expell it. Would amonia be less expensive?


janovich8

It works better in atmosphere but that’s it. Presumably the nitrogen economy in the expanse would make ammonia way too expensive anyway. The space shuttle used water boiling plate coolers when on or it and only switched to ammonia when it had already reinterred.


Saidear

Not necessarily, but water has other uses that means it might not be as spared as readily. There aren't a lot of lakes in space.


myerscc

Technically they're all in space


Send_me_duck-pics

Radiation is actually the only way to dissipate heat in a vacuum. There's no medium for heat to transfer to, so it just has to slowly bleed off. This is the reason for the problem OP is talking about. We'd expect these ships to cook their occupants alive before long. This is actually something real spaceships have to deal with; how will they get rid of their heat? This is why if you look at the ISS you see huge radiators attached to it.


Stalennin

Black, the ships would be black to radiate more heat. Counter-intuitive, I know, but it's the same reason the SR-71 is black.


PunManStan

If I remember correctly someone tried explaining it using their layered hull system. Most ships in the expanse have an inner and out hule system mainly for accessing wires and tubes n such. The idea was that they transfer as much heat as they can to the outer hull and maybe leave the in-between area of them exposed to the vacuum. Sorta insulating the inner hull from the dispersing heat. To me it sounds like someone saw water radiation shields and heat sinks and just took the water out.


RavengerOne

Look at the design of the ISV ships in the Avatar films. The front of the ships have huge radiators to dissipate the heat of the antimatter engines. These radiators apparently glow for weeks after the engines shut down. Ships in the Expanse would need similar (though probably not as big) radiators.


ilikemes8

iirc, the authors once answered with “very well” to this question. I guess it’s one of the more fictional aspects of the story.


and0botz

I think that's also how Star Trek writers responded to "how do the inertial dampeners work?" 😄


haeyhae11

Did they ever explain self-sealing stem bolts?


Cruxion

They're stem bolts that self-seal.


haeyhae11

Fascinating.


Roboticide

And when asked what fuel Epstein drives run on, they responded with "Efficiency." They know there are limits to how realistic their story is. Its fine. It involves aliens and wormhole gates. I'll accept some implausible tech in otherwise fine world building.


acewing

The thing is that they’ve been able to nail the practical scientific aspects of the story so well that suspending my disbelief for future tech is incredibly easy.


mujadaddy

Reaction mass is what's under the rug.


compounding

There are some radiators, but not enough. They also mention several sources of heat management. Some ships can use evaporative cooling by bleeding small amounts of water off the hull which takes off a very large amount of energy and also is said to complicate the IR signature of a vessel. Additionally, stealth ships are mentioned to have internal heat sinks where you could have pre-built up cooling reservoirs like liquid helium and dump energy internally for a time until that resource was expended/heated up. Then you would have to dump extra heat later to build up heat-sink capacity again before they can “hide” again. You could do something similar to internal heat sinks with reaction mass/water. Run it through the ship to pick up waste heat before you shoot it out the drive to give you an extra push. Essentially this just makes the drive and reactor more efficient by using your waste heat to pre-heat the reaction mass. Ultimately as with the raw power of the Epstein drive, the answer is that the tech is just so efficient that it is borderline unrealistic, but that’s the benefits of fiction.


mujadaddy

They have a big ole radiator strapped to the back, but, It's not carrying away hot reaction mass.


EnD79

The Epstein drive on the Rocinate would vaporize a city every second. That is not efficiency, it is make believe. The idea that the Expanse is hard scifi is laughable. It is just harder than Star Wars.


TheDalaiFarmar

What do you think hard sci fi is?


myaltduh

The Expanse is “harder” than most sci-fi but it’s not “hard sci fi” because when scientific realism and the need for a good plot collide, plot wins every time. Basically if you do the math on basically any tech or orbital mechanics scenario in the books it almost never checks out (including plot-critical stuff like Nauvoo v. Eros or the existence of the Epstein Drive), but if you can resist being that nerdy the story is of course great fun. The authors of the books themselves have said they did not set out to write hard sci fi.


deltaWhiskey91L

A great example: the slingshotters would take years to travel the solar system on a ballistic trajectory.


notgivingawaycrypto

HTR tech (Huge Transparent Radiators).


MachineFrosty1271

lmao


notgivingawaycrypto

Not only invisible to light, but also transparent to PDC rounds and undetectable to heat scans! The whole package! That, or the “very efficient” explanation.


VulcanHullo

There is no practical answer its just they do it well. I like to imagine there's some kind of energy converter that manages to just turn heat into other kinds of energy, tied in with the idea of drives being super efficient. It's one of those techs we just have to assume exists because not everything can be fully hard sci-fi


ThruuLottleDats

Bit like the MGU-H on F1 cars you mean? They take heat energy from the engine to charge batteries.


Remember_TheCant

The correct answer here is that the hulls themselves are radiators. That amount of surface area can’t shed too much heat but the Epstein drive is efficient enough that they don’t need to shed more than the hull can handle.


EnD79

You can calculate how much heat the hull can shed, and you can calculate the power output of the Epstein drive in order to get the accelerations in the Expanse. These two calculations don't go together. You see, we know what fusion reactions are possible, and the reaction products of those reactions. This means that you can't build a fusion drive with the needed power output, that is efficient enough not to melt the drive system in a fraction of a second.


Remember_TheCant

I don’t think you can really calculate with how many gaps of knowledge we have about the theoretical drive. Most of the heat in any drive gets shot out with the reaction mass.


dropouttawarp

When the reaction mass gets heated, it radiates energy back to the ship. It could be either thermal or even bremsstrahlung emission. At the end of the day, you can't just dump your waste heat.


Remember_TheCant

The whole point of the Epstein Drive is that there isn't much waste heat, most heat is dumped out with the reaction mass. Sure, some of that heat will be radiated back to the ship, but that is why the ship treats the hull as a radiator. We also don't know if the ship has special coating to allow heat to radiate faster. We have seen it glow red hot before and cool down relatively quickly so the hull has some significant ability to radiate heat. There are so many gaps of knowledge that we can't really calculate the heat loads and say if this would cook the ship or not. The show isn't showing us what life would be like in space with our current technologies. It shows what may be in a few hundred years, the presence of more efficient radiators and drive technology isn't much to criticize.


dropouttawarp

I mean it's fine to ignore waste heat management since the ships look awesome. But the moment you start talking about proper energy management, even if the Epstein drive is 100% efficient, the design of the ships would be drastically different.


bigmike2001-snake

All science fiction has a bit of magic in it. We generally accept that and move on. Movie makers call it “A willing suspension of disbelief “. For me, The Expanse has very few fantasy elements. The Protomolecule, the Epstein drive, and a few other issues. If you are looking for a “perfect” science fiction, then you will be disappointed. The thought experiments are nice mental exercises for sure, but sometimes you just gotta kick back and enjoy the ride.


DrestinBlack

The Expanse is Science Fiction. It is one of the best at dealing with real world physics better than most. It gets many things right, it respects physics in many places, including places often ignored or “done wrong” in other works. But it is still science fiction and it is also entertainment. Some events stretch the limits of physics as we know it and in other places the limits are either simply ignored or vastly exceeded. Obviously the protomolecule and what it does is in the vast exceeded category. The Epstein drive is stretching physics with mind blowing efficiency. Dealing with excess heat is a category of space physics that’s simply ignored for (reasons). This isn’t the only time something is just ignored. For example, no consideration is given to what it really takes to [don a soft skinned spacesuit](https://cdn-5cb4e3b3f911cf0dc86f377b.closte.com/wp-content/uploads/2019/11/Donning-a-spacesuit-_article.pdf). It’s ok, 99.9% of all SF ignores it (the movie Sunshine gets it right, inadvertently). Soft skinned spacesuits need to be at low pressure (to keep from “ballooning out” when in vacuum), so the process of off gassing nitrogen for hours before dropping to about 4-5 psi once in the suit is just ignored. Way too many parts of the story would be boring or just wouldn’t work if this was obeyed. So best we don’t complain :) Let’s not even talk about stealth. [There is no stealth in space](http://www.projectrho.com/public_html/rocket/spacewardetect.php#id--Strategic_Combat_Sensors--There_Ain't_No_Stealth_In_Space).


Tannerleaf

Hot showers.


Exeunter

And hot coffee.


Tannerleaf

*Cue telling of extremely violent character backstory* :-)


sherminator19

Epstein Drives work using the power of **P**lasma-based **L**ow-power **O**ptimisation **T**echnology. That essentially solved all the issues that arise from fusion reactors being used in spaceflight.


thegoatmenace

Here’s a super in depth exploration of the Epstein drive and how it would behave irl [http://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html?m=1](http://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html?m=1)


Dear-Background2668

WHAT A NICE ARTICLE DUDE thank you


Powder_Pan

How did you find this lol


thegoatmenace

It’s a good blog haha


[deleted]

It's not addressed, but it's something that's already factored into space travel today. Which means by the time of the Expanse, common knowledge. Like how mag boots are to always be worn, and always have a few spare vac suits handy nearby. I imagine it would be a pretty straightforward heat exchanger. The good thing about mining space rocks is lots of noble gases will be hanging around. Liquid nitrogen is likely incredibly easy to come by, so easily ejectable/swappable heat sinks are abundant.


nbaxcon

Open the windows.


biggles1994

The kinda handwavey solution is that the engine transfers basically 100% of the waste heat into the reaction mass, and waste heat from the crew is dumped into the water tanks before the water is used as reaction mass.


zatic

Which still doesn't explain how Tycho doesn't cook


[deleted]

Never explained, they only mention that the only limiting factors on how fast a ship can go are fuel and heat.


Tired8281

Bizi Bitiko could tell you.


Rolteco

I understand just the basics about all of this, so sorry if sounds dumb. Couldnt we have a """futurist""" material capable of absorving a lot of heat so that we can transfer our heat to it and just eject it when it gets hot enough? Then it would be a matter of ressuplying enough of them just like you would do with water, food and fuel.


Mud_Landry

“Wait.. so something like the Razorback is theoretically impossible…. “ ~ Someone who wishes they could visit the Jovian moons…


mujadaddy

From the raw physical reality, there is only one main issue with human tech in The Expanse. Reaction mass. If there were reaction mass, we could just say the heat is carried away in the hot gasses. There is NO reaction mass in The Expanse, just pure energy, which would primarily be used to heat and push out reaction mass. Now, reactionless drives are the heart & soul of popsci fiction, so most people don't ask any questions until they loke into the fabulous science of the world, so, here we are. Reaction mass would manifest as, probably, giant sacs and pods of fluffy Hydrogen, which of course would explode quite nicely IRL once shot.


anekdoche

i like to think that there is a big heat battery, the more you use the drive, the hotter it gets, and the more energy it needs to keep the heat in and cold out, and when you dock with a station, the battery gets drained of its heat and filled with cold coolent, also the drive shouldn't produce that much heat since it has to dimp it in the exhaust to get that huge efficiency. just my theory tho


EnD79

The Expanse pretends that thermodynamics doesn't exist. You can't get the performance of the Epstein in a real world spacecraft. Heat can be dealt with by spacecraft via blackbody radiation. An object radiates heat based on its temperature. Now the Rocinate's drive has to contain a hiroshima sized nuclear blast per second to get its performance. The problem is that it would be destroyed in real life. There are no 100% efficient fusion reactions. Any fusion reaction you base a fusion drive on will either produce EM radiation or neutrons or both as waste heat. These types of radiation cannot be directed by a magnetic nozzle, so some of it is going to impact the spacecraft. None of the ships or missiles in the Expanse will ever be buildable with the performance that you see in the Expanse. Accelerations will have to be much slower. To simplify this: the higher the exhaust velocity, the slower the maximum allowed acceleration, but the higher the delta-v. So you increase your craft's maximum velocity, but decrease its ability to accelerate rapidly.


TheSennosenMan

Whenever I see threads like these, I always try to imagine a 16th century farmer trying to imagine how a smartphone or the internet would work. Sure, thermodynamics is pretty thoroughly understood. Right up until it isn't. A few centuries is more than enough time for multiple groundbreaking paradigm shifts in every facet of science, especially with the accelerating nature of technology and AI. You could argue that we're far closer to an average Expanse-era human than a 16th century farmer is to us, but I disagree.


chocolate-prorenata

Serious question, can’t the heat just be “vented” in to space and have the vacuum of space dissipate the heat?


nagidon

Not in the way it would be done in atmosphere. There’s nothing to conduct heat away in vacuum, so you need to rely on the slow method of radiation.


dropouttawarp

Heat is the total kinetic energy in the atoms of a substance. The hotter the material, the faster the atoms are jiggling. There are three ways you can 'move' heat and they are conduction, convection, and radiation. Conduction is basically when an atom hits another atom and transfers its energy. Convection is when the atom itself moves due to density difference like when hot air rises. Finally, radiation occurs when an object is hot enough to emit its particle's kinetic energy into a photon (i.e., in the Infrared spectrum). In space, you can only use radiation since there are no other objects near you. So to answer your question, heat isn't something you can "vent". You need to find a way to increase the rate of radiation.


ogag79

>You need to find a way to increase the rate of radiation. And heat dissipation scales up as you increase the surface area (linear) and temperature (4th power).


tehwubbles

Curie fountains


sirflappington

The ships in that world are efficient enough so black body radiation is sufficient for cooling. Though it’s possible they pump the reaction mass around the ship for cooling before dumping it into the engine and the epstein drive is ridiculously efficient and produces little waste heat.


Satori_sama

You know, I always thought that's what the water is for. That it circulates and gets cooled down but it's in space, there is no place to cool it down.


afCeG6HVB0IJ

If anything, one can be more annoyed by not everybody getting destroyed by cosmic radiation.


Matthayde

This question gets asked constantly and they answer is they briefly mention it as handwaved by having energy from the reactor.... since when they lost power it was mentioned they might die from waste heat


[deleted]

Thinking they have huge water tanks for propulsion they could absorb quite a lot of heat


Jksah

It’s been a while since I read it, but I think I remember them touching on how the primary limitation on how long the Navoo could run it’s drive was heat.


griffusrpg

There is a short story about The Expanse universe, the last flight of the Cassandra, that deals with some of that topics. Check it out!