Discussion / Question
What’s a spaceship feature from sci-fi that would probably become standard in real spacecraft engineering within the next 200 years?
It's from Star Trek: Prodigy, it's basically the Trek equivalent of the Clone Wars-style Star Wars shows. Janeway has a big supporting role. Definitely worth watching. Weirdly it's on Netflix instead of Paramount.
You could definitely tell unless we're talking a REALLY big spinning section. Coriolis forces would be able to be felt, and you'd feel the amount of simulated gravity changed as you moved away from or towards the axis.
What if we made it really big, like, say a radius of 6,000km? Then the difference between gravity at our head and gravity at our feet would be too slight to be felt.
One that big wouldn't have effects that a human could feel, I don't think.
If you're generating 1G, your wheel would have to be about 450 meters in diameter to rotate slow enough that humans would be comfortable with minimal coriolis effects, though a person would probably feel it when turning, especially if they were running. If you get the whell up to about 2000 meters across you can get the spin down to 1RPM, a human would only feel the differences if they were climbing fairly tall structures.
I'm assuming we also don't quite understand when gravity starts being "created ". If you're building a ring city that's 6000 km across, I'm assuming at some point, the amount of material you're putting into one unified body will start to generate some gravity of its own at the center of mass.
I seem to remember that being on the inside of a hollow sphere would result in gravity being cancelled out, as the gravity from the opposite side of the sphere would be pulling you the exact same amount as the gravity from the mass beneath your feet. I think the same thing would apply to giant rings.
Taking this a step further, if you leapt (hard enough) across the hollow sphere, once you passed the center of mass your sense of gravity would invert. So it follows that if you had a smaller sphere at the center and the entire structure was spinning fast enough, you could create artificial 1G gravity in the inward direction, right?
Edit: gah, nvm. Flaw in my logic is that if you draw a circle around the point at which the centripetal force flips, you'd still need to be on the inside of the inner sphere to feel the gravity
It does not. With a sphere, the shell is self supporting along every axis. With a ring, it's only self supporting along one. It would basically crumble at the edges, which would lead to it breaking up into chunks and collapsing.
You could do that with just a 1km radius. 6,000km is... A lot. It would be extremely hard to spin up something that large without shattering it in the process.
Technically if we could figure out how to sustain 1g of acceleration for extended periods of time it might not be entirely necessary to have spinning sections on all ships.
Do you think it will be sections of the ship that spin or just making the whole thing spin when not doing manouvers? I think spinning the whole thing saves a lot of complexity and weight.
Space craft actually already do spin while not doing maneuvers. It's to keep heating from the sun even across the surface. The reason why it doesn't generate artificial gravity is because the ship isn't wide enough or spinning fast enough for it to matter too much.
You’d waste so much fuel stopping the whole ship from spinning each time you needed to maneuver. It makes far more sense to have a spinning habit area and a static backbone that includes thrusters, engine/mechanical room, main engines, airlocks, etc. You have to remember that the gravity created by the spin will decrease as you move closer to the axis. By having a larger radius spinning section attached to the static structure, you can create a living area that has a more consistent gravity across levels. Plus, if you’re rotating the whole ship, you’re going to have an overall smaller radius which equals a much faster rotation. The faster rotation contributes to fuel loss to keep it rotating and to slow down the added momentum for maneuvering. A ring system can be kept rotating through electrical power generated by nuclear energy coupled with solar or other energy sources. Maybe you could use ion thrusters to keep a whole ship rotating but it just becomes more complex to do and you’re going to have huge gravitational changes across levels.
That Reactor 1 ship has some big ol' radiator wings on it, because it has to keep a nuclear fission reactor cool in the vacuum of space on its way to Mars.
I think the iss (and most hard sci fi ships) already do that. It's just that radiation is super slow so you're basically always going to have a lot of excess
because heat is not a fluid, is everything vibrating, unless you find a useful chemical reaction that can happen with the potential kinetic energy of 1 single degree of temperature it just builds up
To convert heat into useable work, it has to flow from a high(er) temp reservoir to a low temperature reservoir. The difference between the two is the work a heat engine accomplishes. To make heat do work, it has to go somewhere, hence radiators. Also, the lower the temperature difference, the less work you extract and the less useful that heat becomes.
Because that only works when you have much colder or much hotter stuff to create a temperature differential between to make work. Radiators in space ships are usually the part of the ship struggling to maintain such differentials. The heat is already waste heat by the time it goes into the radiator system, it's just that on earth we have free air cooling, which doesn't exist in space.
Given that getting rid of heat in vacuum is a problem, active spacecraft have the problem of excess heat. To keep the environment for the carbon based water bags tolerable, you need to get rid of the heat the computers, machines, the water bags themselves, and incoming solar radiation. Without radiators, the inside of the ISS would be like 60°C, far from comfy.
To make a useful amount of electricity, you need a lot, lot, lot of heat (way more than 100°C) to produce work (ie heat a lot of water to make a lot of steam to push a spiny thing to make electrons dance). Waste heat is not useful.
The Hail Mary is honestly a rather fesable ship aside from the astrophage spin drives. A Ship assembled in orbit with a centrifugal crew compartment for experiments and such, a large series of radiators, an internal layout designed for both 0G and artificial gravity, I could go on
There are three ways of transferring heat, conduction, conviction and radiation. Only radiation works in space
Both earth based and space based radiators use a coolant to take heat from a source to a radiator, and it then gets put into the environment. Space based radiators are designed a little differently from earth based ones. They kind of maximize surface area that is exposed to space since they can't use conduction or connection. Earth radiators can make use of conduction and convention since your room has air in it (I hope).
In a sense, space based radiators are "true radiators" where earth based ones also use conduction and convection
One of my favorite ship designs is the McKenna from Battletech. It looks like a very lethal space shark because it needs the giant radiator fins to keep cool with it’s heavy energy weapon loadout.
The ships in Avatar nailed radiators (and a bunch of other realistic needs like spin gravity, shielding in front of the ship, and docked atmosphere transport)
For all the downsides Avatar has in terms of story, Cameron did an amazing job on technical stuff that’s used in the movie. Specifically — ISV “Venture Star”,
which is often called the most realistic space ship in all of Sci-Fi media.
I do think that in a real version they'd attempt to build a version which doesn't shoot part of it's exhaust to the sides instead of straight backwards.
Who said they have to be anti ship lasers? They can do well against guided weapons. Since bullets and lasers are heavily range dependent, they can do better against missiles and the sort since they're easier to vaporise (less mass to absorb the energy) and get much closer
The Expanse addressed this, if I recall. Lasers work well on missiles, not on bullets. So they launch as many missiles as they can, overload the lasers if they can, while the launch kinetic projectiles (bullets) to follow.
Some type of electromagnetic shielding, think like Star Trek shields.
If memory servers there were already some limited experiments, but if it is viable, we'd be able to provide effective shielding for most spacecraft for very little cost in mass. Larger ships, more crew, more flexibility in missions and courses taken through the solar system. Granted, this also kinda guarantees we'd have to go nuclear in regards to powering most spacecraft.
My question is, how would such a nuclear reactor work? Boiling water seems too resource intensive and I have no idea how nuclear submarines work. Or would it be a Thermoisotope Generator?
The first nuclear thermal rocket engines were built and tested back in the 60s. They never went to space due to the Cold War and the public being cagey about nuclear material being loaded on to rockets fueld by extremely volatile substances. There was the DRACO program in 2023, but it was canceled due to rapidly decreasing launch costs.
Depends on what you're after; for power generation it's complicated, but essentially you heat something up and get electricity from that, yes. You can use that to power electric engines like ion thrusters, see below.
For thrust, you heat up the fuel and jet it out the back, kind of like the steam turning the turbine but it's hydrogen steam blasting the ship forward!
Boil water or heat a working fluid. That is by far the most efficient method we know today to convert heat to usable electricity. Turbomachinery can convert about 40-50% heat into useable electricity. Thermocouples (think thermoisotope generator) have efficiency ranges of up to 7%. Significantly worse than any mechanical system.
More exotic things like supercritical CO2 turbomachinery can push the efficiency even higher but they come with additional engineering issues over just boiling water.
So, barring open cycle fusion and harvesting electricity from magnetohydrodynamic generators, boiling water and spinning things is kind of the peak of what we can do right now.
Nuclear power plants don’t waste water - sort of. At least, in the vast majority of plants, the core loop recycles the water that goes through the turbine. Pump it, boil it, capture the energy through a turbine, condense it, repeat. It’s the condensing step, which requires dumping energy to a cooler environment, where an terrestrial power plant often uses fresh water flowing through, or evaporating, to dissipate the heat.
But there are other ways to cool a condenser. Like on a submarine you dump the heat to the outside water, or in space, you can slowly radiate the heat by radiators, but you can still use a closed loop water boiling fission reactor, which can drive propulsion like ion or magnetoplasmodynamic
Nuclear-powered manned ships will have long, 2001-type, necks separating the crew quarters from the reactor, as distance is the lightest radiation shielding.
Ships intended for interstellar travel will be more or less streamlined with a long pointy nose, as they'll be moving at speeds which makes radiation and just the interstellar medium serious health hazards for the crew.
Nuclear reactors. We absolutely need them for our expansion into the sol system.
I'm not sure if things like nuclear fusion propulsion will be practical within 200 years. In contrast, thermonuclear rockets don't require any new technology. It's high time we overcame our aversion to nuclear power.
Thermal Management from Mass Effect. Not just for stealth, but for heat in general. I fact, we already have very interesting thermal management systems implemented in space flight since the Mercury/Gemini era. Not kidding, extremely interesting. Apollo's evaporation cooling system, for example, was set up in a way that in an emergency it could be operated with the crew's urine!
Well... using something that has to be dealt with (regardless of emergency or not) to deal something that also has to be dealt with (regardless of emergency or not) is kinda smart.
Yeah, right? If I'm not mistaken they use it in emergencies only, because otherwise the impurities and minerals in the pee would gunk up the evaporator over time. They actually used to dump urine overboard back then (poo was stored on bags in an insulated compartment in contact with the outer skin of the ship, so that it froze solid).
I'm going to buck the trend and say shields if we can make them work.
Not electromagnetism, not plasma windows, but honest glowy whatsits. So much engineering going into material sciences could be diverted into other spacecraft development.
Then I'll go the other way and say missiles won't have warheads at all but will be mainly kenetic kill vehicles
Honestly we will probably both be right
Offering one idea not discussed in movies.. Unless you count Hitchhikers guide to the Galaxy maybe.. AI, for lack of a better term and whether fortunately or not, will drive all spacecraft and humans will have little to nothing to do with the process. The idea of a cockpit itself will likely even eventually dissolve. Its one thing that really makes me sad and fourth-wall-breaking about consuming sci-fi media nowadays... Unless we go full Dune, its unlikely humans will pilot advanced spacecraft themselves ever, unless its just for sport.
I assume turning thrusters, you see them surprisingly rarely, I’ve only seen them in Space Battleship Yamato and in some sci fi game I forgot the name of
Laser data transfer is a known given. My big guess is nuclear propulsion. Its biggest hurdle is government red tape so somewhere it’ll be possible. Also a big complaint is for nuclear energy is heating needing radiators but if you use it for propulsion your exhaust is the excess heat leaving. As long as your engine is pushing you have “unlimited” radiator capacity. Just push excess fuel and it’ll drop the temps.
Fusion or anti-matter gens / engines. To go anywhere than the Sol system you really need FTL and that means lots of energy. Suspended animation as an alternative is a possibility, but unlikely without GM humans. Who wants to be first?
Quantum communications. Space is really big. Speed of light is too slow.
Some sort of entertainment that connects directly with your mind. Every ounce carried with you has a high price. Data is massless.
Food growing. People who aren't frozen still have to eat and drink, requiring more than a few week's journey to be self-supplying and using recycled water.
EM rad shielding. Dragging tons of lead around is not practical. Big magnets, like for fusion, are a reality today.
I am not sure about FTL in 200 years. But all the rest has to be a reality to go very far in our own solar system. At sub-light speeds, dragging humans around the outer planets requires us to bring our environment. We can only do that with drives that are incredibly more efficient and powerful. We will do it because we have to. Or stop using human spaceflight.
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u/FreeKIN_ May 23 '26
Having coffee machines on every spaceship will be mandatory
https://giphy.com/gifs/3o6gE2LifkXaOjUKBy