/sci/ - Science & Math

>>11942456
>Some other inacuracies you guys can think of?
Naomi wasn't shoved out an airlock the first episode.

There should be no cqb. Ships would engage at such speeds that they would get a shot or two off and then be out of range. Also stealth in space is a meme

>>11942456
>Some other inacuracies you guys can think of?
Sound in space (firing a rocket, explosions, ...)

>>11942481
lel

>>11942456
One of the authors admitted this, but the fusion drives are laughably efficient. Also someone did the math, and calculated that the amount of waste heat they would create at the really high g burns would melt the ship in short order.

>>11942456
There's no way an intelligent species would build "spaceships" to fight with.

>>11942456
>The Normandy's IES (internal emission sink) stealth system is her most notable feature. For centuries, it was assumed that starship stealth was impossible. The heat generated by routine shipboard operations is easily detectable against the near absolute zero background temperature of space. The Normandy, however, is able to temporarily "store" this heat in lithium heat sinks deep within the hull.
>The IES stealth system has a few limitations: The system doesn't work during FTL flight because this blue-shifts the Normandy's emissions beyond the sinks' ability to store, and even while out of FTL, any visual scan (i.e. looking out of a window) will reveal her. However, this is rare since most ships rely on scanners rather than visual contact and spotting another ship in space is difficult. The Normandy can go to 'silent running' for around 2-3 hours, or drift passively through a system for days before having to vent and give away her position. The stored heat must eventually be radiated, or it will build up to levels capable of cooking the crew alive.
I like how they did this in the Mass Effect. It's kinda handwavy about how the technology actually works, but it does mention how some interesting ideas about how we thought stealth systems are impossible, what their limitations are and how they got around it.

>>11942456
According to this guy it was still conceivable.
http://toughsf.blogspot.com/2019/10/the-expanses-epstein-drive.html

>>11942456
There's a Q&A at the end of the first book and one of the question was: "How does the Epstein engine work?" and the response was: "Well Enough:)" Dont expect anything hard-scifi from the Expanse.

>>11942923
It's not just "kinda" handwavy, it's extremely handwavy, and basically irrelevant anyway. Mass effect fields created by ezo manipulation basically let them do magic as a far as technology is concerned, and it's basically the central contrivance of the setting.

In theory cooling a ship by using liquid heat sinks is possible but it's INCREDIBLY IMPRACTICAL because you're adding large amounts of otherwise useless solid mass to your ship that you have to spend even more fuel pushing around, even if you eventually just jettison them like the cooling clips from the guns.

>>11942517
Didn't someone figure out you can kind of pull off space stealth?

>>11943049
You can pull off some denial of intel that can make you stealthy if your enemy isn't looking, but true stealth in space is impossible especially with an enemy who is actively looking for you.

I love realistic sci-fi but the expanse isn't the show for it seeing it has sentient planets.
I just hope "For all mankind" keeps with the level of realism they had in season 1.

>>11942456
There's only one realistic hard scifi story among all the many I have encountered. And it's not the expanse.

>>11943183
Not sure if Drone Riots or mindworm attacks are worse.

>>11943146
Yes that was quite good, although new season 2 trailer seems to play up the action a lot.

>>11942456
I'm fairly certain that heat dissipation is addressed several times in the books. Most ships in the expanse are also built with a double hull design and only the inner hull is pressurized, leaving at least a crawl space of vacuum between both hulls.

>>11942517
That's mostly how it is in the books. They mostly send torpedoes and ward them off with pdcs. Occasionally flybys happen with pdcs firing directly into ships, mostly with devastating effects. But it's kinda hard for a TV show...
>we got fast movers!
>shit, how long we got?
>7 days!

>>11942537
Akshually there is never any sound in space in the Expanse.

>>11942715

I can see spaceships having defensive capabilities for self defense. But yeah, it would be drones that do the fighting otherwise.

>>11943183
>god damn global warming that sinks the entire planet because you insist on building an interlinked cyborg megacity
I'd be mad as fuck if I hadn't nerve stapled myself for the greater good.

>>11942481
fpbp

>>11943183
Oh fuck I haven't played this game in ages. I always play the Russian dude Prohkor Zakharov. Kinda want to play now.

>>11942456
I've always kind of thought about that. The heat and also how the artificial gravity would work.

>>11942456
True, they should be deployed outside combat at least.
Also that gravity slingshotting dude experiencing high Gs, de fuk?

>>11943049
You'd have to match the temperature of the background exactly.
And in space we're taking singel digit kelvin to not show up on thermal.
And that's ignoring radar and regular telescopes...

>>11943052
It's impossible if you are trying to have stealth continuously for all time, but not if you only need brief periods. You can have a magnetically supported bulkhead that stays at the normal temperature for space while having a negligible heat-flux between the space-ship and the bulkhead for a period of time. Eventually it will heat up, but if you can disguise you ship as a rock, then during that period you'll be essentially undetectable from a certain angle.

If you want stealth for missiles, though, that is perfectly fine. Make sure your second stage is near absolute zero with the control systems very thermally isolated inside the payload, accelerate it using the first stage until it hits the cruise speed and it will be thermally invisible as it coasts. You can even have a control system that is mechanical in nature so it doesn't generate almost any heat. The only heat it will have is from the sun, but any rock have those. You go and try to figure out what is a rock and what isn't just by heat alone. You could do that by analyzing its trajectory, but depending on the payload's cross-section even finding it would be extremely hard.

>>11944714
stealth on inert payloads is pretty easy, the problem is that any method of sending it where you want quickly is going to leave behind an extremely visible signature that allows the future trajectory to be calculated even if you can't see the payload itself
there is one kinda exception which is that with things like solar sails you can move payloads around very stealthily, but you can't make a huge sail if you want to stay sneaky so it's limited to fairly slow and small payloads. that's not very useful for weapons, but it's perfect for throwing small camera probes everywhere to catch and analyze thruster burns of anyone trying to send something fast somewhere no matter how sneaky they try to be with it

>>11942517
>>11942456
Remember the scene with the maneuvers around Jupiter's moons? Really this show is not going for full on realism. That particular scene was over the line though, pure star wars level nonsense

>>11944731
I guess it will depend on the performance of future systems. If you have a 3 year period of coasting time, that's plenty of time to make some orbital adjustment using cold-gas and orbital assists. If you are talking about 1 day, then yeah, you are pretty much moving in a straight line. The lauch vehicle may also just be a big fucking railgun too, depending on where you'll be putting it, if it is on a moon or on a ship, the size can vary a lot. But then you could mask your heat signature pretty easily and they would only know you launched something by active sensors. If you have a fixed launch platform on a moon, then there will be no visible heat as you can just dump it on the ground, and if it is a massive space ship then you can just periodically vary the heat going to the radiators so that your adversaries don't know if you actually launched something or if you just turned on the AC.

Ultimately, I think we have so many ifs that we just proved that the scenario for stealth in space is actually quite flexible as to be plausible. It will really depend on the situation and the technology available.

>>11944734
Yeah, they made a blog post about that.

>>11943183
https://www.youtube.com/watch?v=QILNSgou5BY

you cant have stealth in space ill group the arguments for it in the thread up and explain why you cant have it


>running silent

the problem with this is the life support systems for your crew will need to be from 272K- 290K compared to the 3K of space the habitat modules on your ship will stand out

equation for max detection distance for a ship running silent with its engine off using modern technology is:
Rd = 13.4 * sqrt(A) * T2

where:
Rd = detection range (km)
A = spacecraft projected area (m2 )
T = surface temperature (Kelvin, room temperature is about 285-290 K)

>just burn and coast

there are two problems with this one
first: this is for burning then coasting and repeating after some time has pasted if your initial burn is detected you give away your thrust and once they detect you they just need to aim a telescope at you and measure the distance traveled to get your mass and arrival time
second: this is for burning once then coasting the problem with this is your now mouths away form your target that increases the time you can be detected and once again if your initial thrust is detected they know when you'll arrive

there are two exceptions to the no stealth rule
if you hide behind something that can hide your temperature like a planet or a star this falls apart if the emery has 2 ships at each hemisphere of the object
or if your deep inside a gas giant

>>11942481
Next season

Should everything just be the ISS with an engine at the end of a long boom?

>>11944942
You can also try to hide in front of the sun if you are close to it, like from mercury to venus.

There are many ways. You are just not being creative enough. It's just that there isn't one way that will work for every case. It depends on how long do you want to stay undetectable, how far away, if your trajectory is elliptic or hyperbolic, how massive or how large the vessel is, etc. Perhaps you don't need to be stealthy until you are 10km away, just until you are at the nearest object you can hide behind, like an asteroid or moon.

And you yourself posted an equation that just proves that stealth is possible, you just need to set the detection range you want and juggle surface temperature and area around until you have some good mission parameters. Suppose an alien wants to come as close as the moon without being detected by the earth. Then, all you need is [math]\sqrt{A}\ T_S \leq 28.686\cdot10^3 \text{m}\cdot\text{K}[/math]. Using liquid nitrogen to actively cool the earth-facing surface, you can have a temperature of about 70K, which would mean you could have a vessel with a cross-section as large as 167.9km2, which is obviously way too large, as you'd probably be detected by radar by then. So thermal radiation is not a limiting factor for stealth if you place your constraints carefully. You'd probably be limited by how much heat you can pump from your surface without saturating your radiators, or how much power you can generate with onboard resources.

I didn't check your equation, by the way, I hope it's correct.

Here is how stealth works in the expanse:
The ships are coated with a special light and radar absorbing paint, making them pretty much undetectable by radar and visual telescopes or sensors. They have an outer hull that is not pressurized, insulating the inner hull with a shell of vacuum and further shielding it from radiation and scopes. Then they have to run life support system at a minimum and shut down all unnecessary functions, like entertainment feeds, coms, the coffee machines.. The heat they still generate is stored in internal heat sinks/storages and obviously they can not use their drives, only maneuvering thrusters. They still prefer to hide behind objects, even with their stealthships, and their ships or [slight spoiler] other stealth paint coated objects are frequently detected anyway because some sensor notices the weird area of supposedly nothing that is slightly warmer than the space around it.

So there are many restrictions to the tech and it's not like stealth ships are these undetectable superweapons.

>>11944614
>Also that gravity slingshotting dude experiencing high Gs, de fuk?
He's accelerating as hard as possible. Isn't that the point of gravity assists? Would there not be g forces when accelerating?

>>11944537
There is no artificial gravity in the Expanse. It is either generated by spinning, like Ceres Station got spun up by Tycho Company, Tycho Station has a spinning habitation ring, the Nauvoo/Behemoth/Medina Station has the rotating drum. Characters frequently experience nausea from the coriolis force tho, especially when moving closer to the axis of rotation. For example, the cheapest, shittiest parts of Ceres are closest to that axis, where gravity is lowest and coriolis force is highest.
Gravity on ships only exist when the ship is under thrust. That is the advantage of the Epstein drive - because it allows for constant acceleration it not only allows the ships to gain insane speed but also allow a constant, controllable gravity along the thrust vector. That's why ships in the Expanse accelerate halfway to their destination, then do a 'flip & burn baby', turning around and decelerating the rest of the way. So there's constant thrust gravity on ships.
Ships usually cruise at a comfortable 0.3 G acceleration. Enough gravity to take a shower and walk around normally, but not enough to be a problem for the Belters who didn't grow up in a gravity well. Some ships like the Rocinante can pull up to 20 Gs tho, but that would kill the crew even with crash couches and 'the juice', a drug cocktail injected to endure high g forces. Later ships can pull >30 Gs, with the crew dispensed in some sort of breathable liquid chambers..

I mean it's still obviously science FICTION but they did think about a lot of issues.

>>11945331
>Would there not be g forces when accelerating?
Not like that. If he did it like that in real life he'd be ejected to an outer orbit pretty quickly. In bodies with a low mass like those, all you need is a few m/s of delta-v and you're flying away. That whole scene is preposterous.

>>11945348
Those racers have tiny ships and he could use thrusters to stay in orbit until he wants to eject. And he was there only for a few seconds..

>>11945073
If we ever end up with space travel being a normal part of life, my guess is the space craft that don't need to land in a gravity well will end up looking like a Borg cube or an oil refinery.

>>11945331
>He's accelerating as hard as possible.
Yeah, and so is his ship. It's still just an orbit, both him and his ship are essentially in free fall.
>>11945348
that's... not the problem at all but whatever

>>11945435
I don't understand. Why would he not feel acceleration when is ship accelerates? How is that different from a fighter jet, for example?

>>11945240
>how far away
right the main problem is in thrust power the space shuttles thrust power is 13.7GW(https://hypertextbook.com/facts/2001/StaverieBoundouris.shtml)) with current technology it would have been detected past the orbit of Pluto
if you want a tested example voyager 1 is 18,000,000,000 km away its radio signal is only 20 watts but the green bank telescope can pick it out from the background noise in a second
future technology will be better then this

the ships in the expanse are torchships and have a thrust power in the terawatts

>elliptic or hyperbolic

temperature is omnidirectional in space and theres no air or other medium to cool it down

>how massive or how large the vessel is

bigger ship means more thrustpower

>Using liquid nitrogen to actively cool the earth-facing surface

bitch what the fuck

you realize that energy has the go somewhere you cant just even if you could to actively refrigerate your ship you need power so you fire up your nuclear reactor and you have a hot spot on your ship thats 800K at minimum all you've down is create more waste heat by doing that lets say your still going with that you will then need to increase the surface area on your radiators witch just increases your mass

>70K

still to hot space is 3K

>limited by how much heat you can pump from your surface

unless you want your crew to boil alive you can't change that

>√ TS≤28.686⋅10^3m⋅K please reread the units for the equation input the temperature and try again the values you have provided still dont prove your point

>>11945465
>temperature is omnidirectional in space and theres no air or other medium to cool it down
That's not my point at all. The trajectory dictates how long you have for maneuvers.
>you realize that energy has the go somewhere you cant just even if you could to actively refrigerate your ship you need power so you fire up your nuclear reactor and you have a hot spot on your ship thats 800K at minimum all you've down is create more waste heat by doing that lets say your still going with that you will then need to increase the surface area on your radiators witch just increases your mass
Yeah, so long as the energy is not going towards the enemy sensor, you can output as much power as you want. As you said, in space there's no air to disperse the energy back. So, if you make sure the cool surface is facing towards the place you want to stay hidden from, if you can power your radiators without them melting, you can mantain an arbitrary temperature difference. It's basic thermodynamics.
[math]\frac{Q_H-Q_C}{Q_H} = 1 - \frac{T_C}{T_H}[/math]
Again, this is only limited by how much power you can store inside the ship.
>you will then need to increase the surface area on your radiators witch just increases your mass
Your radiators are only limited by how hot they can be without melting completely. And they can output an energy that is proportional to T^4. It won't be as efficient as if they were omni-directional, but they'll still work. You just need a lot of power to compress whatever is the heat medium you'll be using to make induce a heat-flux.
>please reread the units for the equation input the temperature and try again the values you have provided still dont prove your point
I did, if you want to make the calculation yourself, the distance to the moon from the earth is 384402km.

You are not thinking like an engineer. You are coming up with problems without coming up with solutions.

>>11945435
That's not how acceleration works. If you are under thrust, you are not in free fall and you'll feel the acceleration due to your own mass and inertia.

>>11945482
it's pretty trivially easy to just throw fucktons of very hard to detect solar sail camera probes all across the solar solar system in any setting where this kind of shit is relevant though, directional heat shielding or hiding behind other bodies is really not a good solution for stealth in space

>>11945486
>>11945435
The slingshot racers are not under thrust from their engines. However, I read a bit about it and the consensus seems to be indeed that since the gravity of the orbital body you slingshot around acts on you at the same time as the ship, you would not feel the acceleration. Intuitively this does not make sense to me tho.
For an in universe explanation, I'd argue that there slingshotters are trying to gain as much speed as possible, so they might accidentally go into an orbit that's too low and get decelerated by whatever atmosphere there might be. Also, they might use their thrusters to adjust their orbit and would certainly feel g forces from that. Additionally, they're not scientists but reckless Belters, flying heaps of scrap with an engine welded to the back. So who knows how accurate or good their sensors are? They might indeed accidentally into the atmosphere or whatever.. Or they're cheating and using their drive.

>>11945465
>70K
>still to hot space is 3K
I'm only using the equation provided. The equation relates the detection distance to area and temperature. I chose a temperature, and the equation provided de maximum area I could have so I wouldn't be detected. Is the equation wrong?

>>11945489
It depends on the mission. If you want to be absolutely invisible, well nothing can do that. Not even submarines. There's always a way to detect anything. But it will depend on the mission parameters how long you want to remain unnoticed. If your adversary is god and has an inexhaustible ammount of sensors and data processing capabilities, then yeah, you'll have trouble going pass them. But that's the whole point. You can't have sensors everywhere that work all the time and that all the data is processed at real time. You'll have to fit the mission to your technological capabilities.

The point is, no, it's not impossible. It will depend on the technological capabilities of the adversary.

>>11942456
>Some other inacuracies you guys can think of?

Lack of radiation shielding. You need several meters of plastic/water/fuel/soil around the habitat section of the ship in order to protect against galactic cosmic rays.

>>11945240
interesting

>>11945489
Space is still pretty huge tho and in the Expanse, there are probably tens of thousands of ships flying through the system, there are stations, asteroid stations, bases on lots of moons that also would emit heat. So it's not like you'd have to detect that one anomaly in an empty void. You'd have to detect that one anomaly in a pretty busy void, and it might just be hiding behind the drive plume of another ship, like they frequently do in the books.
One tactic used by stealth ships is to have fake transponder codes and tinker with their drive signature, making them look like a much smaller or different ship. Hiding in plain sight basically. And of course they have jammers and lasers to destroy cameras if they should detect them.
So it's not perfect stealth but it's also not impossible to hide.

>>11945501
It was said itt that most ships have double hulled designs. Single hulled ships are only used briefly or the passengers wear eva suits. Epstein drives most likely create a strong magnetic field around the ship and then we also have whatever advanced materials we'd have in the year 2300.

>>11945510
The gap between the hulls is shown as empty in the show, with Amos going in there to perform repairs during combat.

>>11945512
Yea it's empty except for some hardware and it's not pressurized. But it's an additional layer of material, shielding the inner hull from radiation.

>>11945501
With the amount of power they have available at those ships, I think perhaps some active EM shielding would work. They obviously aren't worried about running out of fuel. I think it's probably the best bet for real life ships as well, if you are going to spend a significant amount of time in space. But I'm not an expert.

>>11942456
>>11942690
>>11943001
The engines are also "Reactionless" thruster, there's not enough propellant to actually call it fusion.
We've never had any real, scientifically verified indication that it was possible.

The Expanse does have glorious design thought

>>11942923
Mass effect is soft SF pseudoscience, a complete handwave. The idea of "storing the heat" break thermodynamic in as many way as Star wars do.
There's no reason to make it sound like it's any different.
Having spaceship shaped like spaceplane should have tipped you off.

STEALTH IN SPACE

Glad to see everyone like discussing this in details, for information there's already a place who answered the basic question about it,

http://www.projectrho.com/public_html/rocket/spacewardetect.php#id--Strategic_Combat_Sensors--There_Ain't_No_Stealth_In_Space--Nicoll's_Law

>>11945457
He is basicly falling, his body and ship are accellerated at the exact same rate, so his accelleration relative to his ship is 0 m/s2.

>>11945783
I think I get it now. Pretty spooky desu.
Whats the limit of gravity assists? What velocity could be achieved?

>>11945866
Well, the hard limit is the speed of light.
The practical limit is that you need to pass several heavy objects in a row to gain a lot of speed and we only have 8 planets, not all of wich are realy useable for that and some combinations only at certain times.
Especialy Jupiter is usefull for missions to the outer solar system because it has such a strong gravity and is on the way there anyway.

>>11945866
>Whats the limit of gravity assists? What velocity could be achieved?
The limit is wether or not you are spending more energy or time lining up for a gravity assist than going where you want.
It require planet to be at precise position, you can sacrifice time and spend several decade to not use any fuel, or you can spend more money for fuel and get there with less.

If we had the propulsion shown in The Expanse, gravity assist would be meaningless except as a sport.

>>11945920
>>11945906
Pretty interesting. Could you somehow accelerate while staying in orbit of a planet until a desired velocity? Or would the thrust required to keep a ship in orbit break too much?

>>11945920
It would still be free which means it would be used when using it doesn't sacrifice (much) time. It's like how hot air balloons would exclusively use the winds and weather to move while a commercial airliner of today can ignore them at it's leisure but still uses them when it's economic to do so.

>>11945974
I think I see what you are imagining,
1) You would not get any gravity assist from a circular orbit.
2) The effort needed to do so would far outweigh whatever you'd gain from an ecliptic boost, see below.

You can use the planet you are already orbiting to get a boost with some parameter:
- You are already in an orbit with free room below (no atmosphere, no surface)
- You burn so as to make your orbit pass closer near the planet
- Burning at the lowest point of the orbit will give you a boost.

This is what decent players do in the game Kerbal Space Program when they started high or have a low thrust engine.

You can also imagine some very real (if costly) SF method: Building a magnetic accelerator around a planet, accelerate your ship inside as much as structurally possible.
Note that the accelerator-ring itself will loose/gain speed (if in orbit). This is among the way an Orbital ring megastructure could be used.

>>11946000
(about Expanse reactionless thruster)
Technically correct but only if it happen to already be on your way which is going to be extremely rare. It's not free if you loose more time setting it up, and time is more costly than a few megawatt.

In the Expanse universe every ship use Brachistochrone transfer, that's the requirement to avoid cruising for years.

>>11943146
What are you comparing it to? If we're talking live action series it's orders of magnitude above everything else

>>11945750
That page is pure shit, sorry.
>does not source its equations
>brings up a bunch of problems but does not address the solutions
For example, this part:
>Glancing at the above equation it is evident that the lower the spacecraft's temperature, the harder it is to detect. "Aha!" you say, "why not refrigerate the ship and radiate the heat from the side facing away from the enemy?"
>Ken Burnside explains why not. To actively refrigerate, you need power. So you have to fire up the nuclear reactor. Suddenly you have a hot spot on your ship that is about 800 K, minimum, so you now have even more waste heat to dump.
>This means a larger radiator surface to dump all the heat, which means more mass. Much more mass.
1st, no it doesn't. If you have a better radiator that is able to go hotter, you can have less area. 2nd, yes, the more power you need to dump, the more you need power and the more power you'll need to dump. It's not a divergent feedback-loop, though, since radiators can dump with T^4, while the waste heat generated by whatever generator you have is unlikely to scale that way. So all that does is it puts constraints in your system, it does not mean it's impossible.

That whole article is just "it's too hard, why even try?" No shit! Yeah, it's hard. Space is hard, and stealth is even harder. There's nothing saying that it's impossible, however.

>>11943049

Yes, but it's going to be a very slow ship with a very low payload and vulnerable to targets with high density of sensors.

>>11945486
>If you are under thrust
But he's not

>>11942456
Radiators are ugly.

>>11946706
What do you mean by source its equations? It's math and the engineering part is plain physics.

It IS impossible within the expectation (stealth warship) discussed, don't sperg because of a technicality. Plus the best we can do is still >>11946717, it's slow, it can't fight, it will be detected the second it do something useful and apparently it still rely on the enemy not believing it can exist and not using the best sensor.

>>11945735
Wheels can be used as thrusters. They spin and shit.

>>11946806
Please, derive this equation for me using your math and engineering that's just plain physics.

>>11942715
The Rocinante does have it's own drone.

>>11946816
The data you want is here, a chapter above
https://groups.google.com/forum/#!topic/rec.arts.sf.science/-E6r2F8rgnQ%5B151-175%5D
https://web.archive.org/web/20030510193317/http://kirk.usc.edu/bio/schilling.html

>>11946828
I've read that. If you could just screenshot the derivation for me, I'll drop this point immediatly.

>>11946811
Not really thruster then, those are for attitude control or storing energy.

>>11946838
>https://www.wolframalpha.com/input/?i=x%3D13.4*%28y%5E2%29%5E%281%2F2%29

Not him, but whats the point?

>>11946838
I was going to ask why you wanted it but >>11946855 Ninjaed me in a less lazy way.

>>11946855
m8 wat
That's not even the same equation.

>>11946858
Because I can't just trust a random equation anyone posts. It's not scientific. Where does the 13.4 coefficient comes from?

>>11946873
>That's not even the same equation.
Shit man, don't make me work.
>https://www.wolframalpha.com/input/?i=x%3D13.4*%28y%29%5E%281%2F2%29*z%5E2

>>11946881
Yeah, thanks m8, that's all I wanted.

Now, let's not beat around the bush. The article makes up some equations that come out of nowhere with no derivations or sources. But forget about that. You can use that same equation to come up with restrictions to the vessel you want (should it be accurate). But then let's go to the page once again.

Pic related just goes against the whole argument of the page (with another unsourced equation). This isn't a scientific article. This is a biased piece of entertainment that decided to take the point of view of the person who wrote it. Yeah, it has some nice information inside, like a list of sensors, some stuff like that all aggregated in the same place, but to extract scientific knowledge from that we need to disregard all the bias and look at it objectively. Come up with restrictions to the space-craft and list:

The area can't be higher than A m^2
The power output has to be greater than P
The power source must last longer than t seconds
It will weight W kg, so it must have a thrust of at least T

Note that many of those would depend of the mission, how long you want to remain unnoticed, how fast you want to maneuver (if at all), if you want a manned ship or not, if it's an inert payload, etc. In the end we might end up with inconsistent requirements that prove it's not possible for a specific mission. This article doesn't do any of that. It's not science. It's entertainment.

There's also the fact that to detect something you have to look for something. In the Expanse, stealth tech is bleeding edge new tech, extremely classified and only Mars can make it. It's a huge deal when earth catches that Belter smuggling stealth tech because they were not even sure the tech existed.
So nobody is looking for stealth ships, or scanning random regions of space for temperature anomalies, or even thinking about looking for stealth ships. Even Mars own battleships are surprised when stealth ships show up.
Under these circumstances it's very possible to be stealthy because even if someone saw your drive or heat, you'd just need a fake transponder code and you're good.

>>11946917

The point of the page is
>Act as a synthesis of all hard-science fiction
>Act as a synthesis of many concepts from rocket science to biology or even sociology
>Do this in a very accesible manner so people stop complaining(hard-sci is hard guize!)
>By achieving all of the above promote more scientific realism in media entertainment and maybe media in general

So for example, let's compare how a similar page explains the Tsiolkovsky equation.

>http://www.braeunig.us/space/index.ht
>http://www.projectrho.com/public_html/rocket/engines.php#id--Delta-V

While the braeunig page is amazingly well explained and tells you exactly how deltaV works and is obtained, project rho talks about the implications and provides live examples of those implications without crunching numbers.

So, many equations have out-nowhere-constants? Yes, but if you see the summary:
>http://www.projectrho.com/public_html/rocket/appequations.php
And realize that there is a section for the euler number, so you can guess that a critical public made up of astrophyisics is not the target of the site but rather.

And the equation summary does not include all the equations of the site, just the most basic and comprehensible ones that do not have what you describe.
>Bu... but many people are blindly claiming shit like >>11942517 because of this site
yes, but at least if you challenge them they will offer some arguments and reasons that can be discussed, even if it's parroting projectrho is something that 10 years ago was almost impossible to see. Now, thanks to projectrho there have ben a surge of several novels and games that try to do hard-sci right without being astrophysicists.

So if your complain is that the page is not scientific enough for you. You are right, equations are not explained or derived, just given away and the sources are barely quoted and do not fit anything like the APA rules of quotation, but you are also missing the point and the impact of the site.

>>11946917
From the very second the website say "Spaceship" you are supposed to accept that any opinion presented here is subject to technological and setting uncertainty.
It's goal is to allow us to make more credible Science-fiction. You'll notice it have a page for FTL.

A "perfect" scientific article would have simply limited itself to our technological level because science forbid baseless speculation so we wouldn't even have this discussion.

This website tell you for example how to get good space pirate when you can't hide behind the horizon anymore or pretend to be a non-indexed merchant ship.
http://www.projectrho.com/public_html/rocket/pirate.php

>>11946959
>nobody is looking
Is a poor excuse for something they have the means to do. The page linked earlier show you that current technology could easily scan everything 360°.
You are just supposed to accept the argument from a meta perspective, "somehow, in this universe, stealth and reactionless thruster are possible".

>Under these circumstances it's very possible to be stealthy because even if someone saw your drive or heat, you'd just need a fake transponder code and you're good.
This only work if (as they mention) you can modify your engine signature to look like something else. Also in a world where spaceship can be used as weapon of mass destruction, it is improbable even a political clusterfuck would allow civilian ship to fly with fake transponder and not require them to identify themselves if they get anywhere with economic importance.

The world of The Expanse rely on some very fun but unrealistic assumption.

>>11947005
>allow civilian ship to fly with fake transponder
Well the point of a fake ID is that nobody knows its fake.

>The world of The Expanse rely on some very fun but unrealistic assumption.
Yeah, obviously. It's science fiction after all. At least it's trying and offering some believable explanations.

Are there any realistic sci fi stories?

>>11946992
I agree with you. I have some critiscism that does not relate to it being unscientific, but I don't really think it's all bad. The thing is, we can't just drop this page and claim "stealth is impossible! project rho says so!". We certainly can't do that in a science board as if we were having a scientific discussion.

To make the page better, I'd suggest removing the whole "there is no stealth in space" thing, because on the bottom of the page itself it clams the complete opposite with "stealth in space is possible". A little consistency would be appreciated. If the goal you have is to have better science fiction, you certainly won't do that by claiming two opposite things at once. Just make sure the readers know what the restrictions are for stealth missions in space and that no, you'll not have your invisibility cloack in a hard-sf universe.

>>11947005
>A "perfect" scientific article would have simply limited itself to our technological level because science forbid baseless speculation so we wouldn't even have this discussion.
I don't think that is true. There would never be any technological progress if we limited ourselves only to what we know it's possible. A "perfect" scientific article could deduce the power requirements for an onboard reactor, or the necessary melting point for the material of the radiator. It does a little bit of that later on when it's not trying to claim "it' impossible guys, stop trying!".

>>11945291
The ships are made out of orions arm magicium?

https://orionsarm.com/forum/archive/index.php?thread-954.html

>A substance that absorbs 100% of all radiation and converts it to energy with 100% thermal immunity.

>>11947030
>Well the point of a fake ID is that nobody knows its fake.
I phrased it poorly. I meant that they would not allow a fake ID to be feasible without incredible means.

>Are there any realistic sci fi stories?
Depend of your criteria. I can list quite a few as manga and anime goes but I suspect you'll know most of them.
Movie: The Martian (except the design)
GRAVITY (they are loose with the math but that's fun)
anime : PLANETES (prefer the anime)
Manga: Space Brother
Mirai no Futatsu no Kao (The two face of tomorrow) adapted from a novel
2001:Night story (and other derivative)

That was the top of my head.

>>11947047
Point, but a scientific article would not goes into long speculative example or setting, they would get called "mainstream trash".
You can ask for more consistency but "there is no stealth in space" is going to stay as 99% of the way fiction use that trope for are debunked and the restriction left make it less stealth than disguise.
...unless we discovers some incredible new science, or FTL trick, but those have the potential to destroy the setting you wanted stealth in.

>>11945291
So basically the same way stealth tech works in real life, they are not invisible to radar, but they are very small on scopes...so hiding near asteroids is good idea because maybe you'd be mistaken for one.

>>11947093
I don't think they absorb all of it, but a lot. The coating is used later in the book to some devastating effect.

>>11947109
Yep. Or behind stations or other ships.

>>11947107
Thanks
Where can I watch those animes?

>>11947109
Stealth IRL is being less and less feasible. Air-fighter are being equipped with IR sensor, the US flying clusterfuck have a 360° one, and radar are getting smarter along more sensitive.
If you have the radar signature of a bird but fly at 800km/h you are going to trigger someone's sensor.
And this is on Earth where the horizon is still a good hiding place.

In space, hiding behind an asteroid would be impossible since what will be tracked is your IR signature, even if you could only be detected with your drive active, any competent controller will notice it and may have an automatic trigger for "unknown ID staying nearby asteroid"

>>11947135
>Yep. Or behind stations or other ships.
...assuming those don't immediately detect you and share your position. Civilian and military aircraft don't (all) have 360° sensor (yet) because they have no need for them. But a spaceship likely would for different reasons.
Also a far away sensor would still detect 2 active engines/reactor somewhere there's supposed to be only one.

>>11947135
>Where can I watch those animes?
...by the known and absolutely legal means and not say "torrent" or illegal "manga4life" filthy pirate website.
Up to you.

>>11947107
>Planetes, with an E
This has a 6 foot tall Lunarian jb qt.

>>11947150
>not flying towards a big rock for dayss with nothing but cold gas thrusters and the chilling out inside in a space suit waiting for someone to cross your path

>>11946189
Are you talking about the expanse or for all mankind? If the later I agree.

>>11947030
>Are there any realistic sci fi stories?
By definition no story is realistic, so for example: Footfall has the spaceship launch with an orion engine but the engines start while the ship is inside the atmosphere so the pushing plate should burn before reaching the atmosphere(and that's without explaining how much acceleration it would impose on the crew). But you can get sci fi stories that respect science and at least try to ground them in some basic concepts like thermodynamics(always avoid quantum stuff tho, it's 95% of the times bad or a mere excuse to handwave stuff).

In this regard, I would say that the moon is a harsh mistress is a very good book.

>>11947190
I saw the trailer for For All Mankind's second season, why do the astronauts have assault rifles? Looks interesting but I refuse to give Apple money because I hate them almost as much as I hate Disney. I'll stick to The Expanse.

>>11947228
Pirate it, I do.
First season is great, basically a lot of shit that was actually planned but ditched with NASA funding was slashed after the moon landings. It's even better if you are a huge rocketry nerd, you will recognize engines from the time on designs that were never built.
As for the weapons the tl:dr is
>USSR beats US to moon
>USSR and US both build research bases
>both spy on eachother
>spying leads to sabotage
>sabotage leads to militarization of the bases

I'm not too keen on the military angle but the rocketry is the most realistic I have seen in fiction.

>>11947047
>To make the page better, I'd suggest removing the whole "there is no stealth in space" thing,
To say the truth. I have seen the evolution of the page and, while it started as a mere collection of equations and ideas, over time the author has cleaned and added many more things and sometimes even contradicting or correcting himself, for example:
>http://www.projectrho.com/public_html/rocket/spacegunconvent.php#bombpumpedlaser
>Bomb-pumped lasers do not use lenses or mirrors (because there ain't no such thing as an x-ray mirror). Brian Smith-Winsemius gently pointed out to me that I do not know what I am talking about, since he works with x-ray mirrors every day.

He points out himself that he is not exactly a trustfull source and, when corrected, he puts the correction and the arguments. So the section is not contradictory, but rather a way to express that no everything is black or white(but he of course stands in the white)

Another example:
>http://www.projectrho.com/public_html/rocket/landing.php#id--Technobabble_Landing_Legs
>(ed note: Rick Sternbach dropped me an email with some commentary. Which reminds me that more people read this website than I realize so I would do well by being more polite.)
He wasn't even wrong in this part, but he still put the other side arguments.

Therefore, what you see there is a mishmash of ideas and comments and discussions. In fact, the problem that projectrho is facing right now is that everything is so chaotic that trying to find anything specific can take up to an entire hour(it took me 15 minutes to find the x-ray mirror thing and I already knew, minor or less, where it was).

>>11947228
>>11943146
>For all mankind
I didn't know about this. I'll try it sometime. Hopefully it won't be a big disappointment.

>>11947278
> I'll try it sometime
Pirate it, the series is quite pozzed so be prepared for some hard woke and metoo shit starting from the first episode in fact.

>>11947287
I keep seeing people saying shit like this, what exactly do you have an issue with?
(not that anon, I have seen it)

>>11947297
Because suddenly it's not a NASA program for all mankind but a project for white men to feel manly about it
>Female astronauts not being given any chances, not for any particular rational reason jjust because they have to
>The wives of the astronauts "sacrificing" themselves in the name of the program by supporting the missbehehaviour of their husbands(this one I couldn't take), so is not even about the men advancing the human barriers but the women shutting up in the name of the heteropatriarchal system.
>Women not being given an opportunity to occupy a position they are qualified and show competence for and being "mansplained" about it later(it's in the first episode and the scene is pretty cringy no NASA scientist at the time would ever find itself in such a pitch but he has to, because he is white, male and the plot and agenda demands it)
Overall pretty disgusting stuff: Perverting an ideologically pure endeavour, and precisely in it's golden, era to push a present agenda. Even warrior-nun is less pozzed(it has 3-5 events like the church being a machine of oppresing masses but specially women and never recieving answer, but SENPAI has it in every episode and sometimes more than one scene) and it's a series about fighting women that need no man.

>>11947342
>SENPAI
Uh? I wrote SENPAI, as For all Mankind.

>>11947347
F-A-M

>>11947347
Hehehe

>>11947342
I see some of your points but I think a lot of the womyn is historically accurate, the USSR used women for propaganda showing how they had more autonomy there (in some ways they did). So to try and turn American women away from the allure of communism the US started pushing women into domestic propaganda.
I 100% believe if the USSR got a man on the moon the nest step would be a woman and the US would send women too for this reason.

The only thing that really irked me was the chick breaking her arm to get the nutty guy home but even that made sense in the story because that would leave the mission commander to stay, chain of command yo.

>>11946706
>If you have a better radiator that is able to go hotter, you can have less area.

how much crack do you smoke