NASA to revive the NERVA engine concept.

[Thekri]

Don't submarines use nuclear engines? Surely the same principal would apply to a spaceship for near unlimited amount of fuel? At which point it's only food/water that is the problem for longer trips.

Nope, no real principles from submarine engines translate to space. Nuclear "Engines" on Submarines are not actually nuclear engines at all. They are steam engines.

The way they work, is the submarine has a nuclear reactor that makes water hot. That is all the nuclear reactor does, it takes cold water and makes it hot enough to turn to vapor. That steam is then fed into steam turbines, which use the pressure generated to turn a mechanical drive that is connected to the submarines propellers. The Submarine moves through the water with the propeller. The steam turbines also power generators that provide all the electrical power for the submarine for stuff like life support and steering. Now you can actually hook this system up to any form of mechanical propulsion you want, as long as you can drive it by turning a shaft. Wheels? Tracks? Hydrojets? All perfectly fine, just hook them to the drive shaft.

However none of those work in space. You could still run a nuclear reactor, but it would be a bad idea, because it is basically impossible to vent heat as fast as the reactor produces it. In a normal steam turbine you want the water to cool down, then cycle it back into the reactor to heat again. In space, there really isn't anywhere for that heat to go, once something gets hot it kind of just stays hot for a very long time. Second problem is that there is nothing really that can make you move by just turning a drive shaft. All of those forms of movement require something to push against to move the vehicle forward, it can push against water, air, or the ground, but it can't push against nothing.

So any form of nuclear engine on a space ship has to use a fundamentally different principle. The one being discussed here basically focuses the heat on a small amount of Hydrogen, and then shoots that hydrogen at the speed of Plaid. Which makes the vehicle go in the opposite direction of the junk of hydrogen you just yeeted into the cosmos. Basically it is traveling by shooting a radioactive gun in one direction so the recoil knocks you in the direction you want to go. You need fuel to run the reactor, and "Ammo" to keep shooting until you get to the desired speed (And you need the same amount of ammo if you ever want to slow down again)

[Mister K]

Nope, no real principles from submarine engines translate to space. Nuclear "Engines" on Submarines are not actually nuclear engines at all. They are steam engines.

The way they work, is the submarine has a nuclear reactor that makes water hot. That is all the nuclear reactor does, it takes cold water and makes it hot enough to turn to vapor. That steam is then fed into steam turbines, which use the pressure generated to turn a mechanical drive that is connected to the submarines propellers. The Submarine moves through the water with the propeller. The steam turbines also power generators that provide all the electrical power for the submarine for stuff like life support and steering. Now you can actually hook this system up to any form of mechanical propulsion you want, as long as you can drive it by turning a shaft. Wheels? Tracks? Hydrojets? All perfectly fine, just hook them to the drive shaft.

However none of those work in space. You could still run a nuclear reactor, but it would be a bad idea, because it is basically impossible to vent heat as fast as the reactor produces it. In a normal steam turbine you want the water to cool down, then cycle it back into the reactor to heat again. In space, there really isn't anywhere for that heat to go, once something gets hot it kind of just stays hot for a very long time. Second problem is that there is nothing really that can make you move by just turning a drive shaft. All of those forms of movement require something to push against to move the vehicle forward, it can push against water, air, or the ground, but it can't push against nothing.

So any form of nuclear engine on a space ship has to use a fundamentally different principle. The one being discussed here basically focuses the heat on a small amount of Hydrogen, and then shoots that hydrogen at the speed of Plaid. Which makes the vehicle go in the opposite direction of the junk of hydrogen you just yeeted into the cosmos. Basically it is traveling by shooting a radioactive gun in one direction so the recoil knocks you in the direction you want to go. You need fuel to run the reactor, and "Ammo" to keep shooting until you get to the desired speed (And you need the same amount of ammo if you ever want to slow down again)

Bloody hell, thank you! In terms of heat venting, is it not easier in space if the engine is somehow exposed or fitted with some heat transfer as space its cold?

Totally unrelated. Could magnetic fields push an object if great enough? If you could replicate earths magnetic field on a spaceship, you could use that as energy to propel? Maybe one day we will know about "bending" space and gravity to use that as the source of transportation.

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No, not even close in fact. Anything that works in air or water can take advantage of the fact that there is a medium to "push against", i.e. using mechanical energy to move the medium (air/water) in one direction produces thrust in the opposite direction.

In vacuum and in space there's no medium to move around, so to produce any thrust you need to bring everything with you, fuel to run the engine and fuel to eject to produce thrust.

Ah thanks. When it comes to these topics I have no clue, fascinated by all things space/engineering but don't know much of the actual science.

[Thekri]

Bloody hell, thank you! In terms of heat venting, is it not easier in space if the engine is somehow exposed or fitted with some heat transfer as space its cold?

No, it is extremely difficult in space, because space isn't really "Cold" in the way things on earth are "Cold". Space is really just empty. It is cold, but there just isn't enough matter there to absorb any energy. So on earth, things "Cool" primarily by passing heat to something else. So for instance on your refrigerator, if you touch the coils on the back, you will burn your hand really badly. What it is doing is taking all the heat in your refrigerator, and using it to make the cooling fluid on the back very hot, then cycling it through thin tubes until the heat is transferred into the air again. In space, there is nothing to pass the heat too, so everything is essentially insulted. If you want to lose heat, you generally have to make something hot and dump it. The dumped thing will eventually cool down, because space really is cold, but it will take years or decades to actually cool.

Totally unrelated. Could magnetic fields push an object if great enough? If you could replicate earths magnetic field on a spaceship, you could use that as energy to propel? Maybe one day we will know about "bending" space and gravity to use that as the source of transportation.

Magnetic fields are sadly, not magic. They work the same way as anything else, they have to push against something else. You can use magnets to push away from other magnetic things, but you can't push against your own space ship without canceling itself out. As far as pushing off other things, the square cube law gets brutal real fast.

Basically, if you are pushing something with a magnet, if it is twice as far away, you have to push it 4 times as hard to get the same effect. So an object 1 miles away might take 1 gallon of fuel to go 1 MPH faster, an object 2 miles away would take 4 gallons of fuel, an object 32 miles away would take 1024 gallons of fuel and an object 256 miles away would take 65,536 gallons of fuel for the same effect. Mars is a minimum of 33 million miles away and an average of 140 million miles away, which means using that simple scale it would take roughly... several million times more mass in fuel then exists in the entire solar system to accelerate an object that far away from earth.

[Masark]

Bloody hell, thank you! In terms of heat venting, is it not easier in space if the engine is somehow exposed or fitted with some heat transfer as space its cold?

No. Space isn't cold so much as it is empty.

Keeping things cool in space is a significant problem, because it is empty. Emptiness means no conduction or convection, only radiation, which is the least effective means of getting rid of heat.

It's cold as far as our bodies are concerned, as the lack of anything (specifically, air pressure) means that water will instantly boil, taking heat with it.

[Gref]

the flat earthers must be feeling damn special as I have seen here. No space, no nothing. where do they think they live?
are we in an aquarium? I am off to google to see what they propose.

I swear these have the same brain cells as dumb fucks saying then send the rocket to the sun at night when it is cool .

bloody hell ffs. WHen humanity moves across the stars, let these rot here.

[Chairman Sheng-Ji Yang]

Nope, no real principles from submarine engines translate to space. Nuclear "Engines" on Submarines are not actually nuclear engines at all. They are steam engines.

The way they work, is the submarine has a nuclear reactor that makes water hot. That is all the nuclear reactor does, it takes cold water and makes it hot enough to turn to vapor. That steam is then fed into steam turbines, which use the pressure generated to turn a mechanical drive that is connected to the submarines propellers. The Submarine moves through the water with the propeller. The steam turbines also power generators that provide all the electrical power for the submarine for stuff like life support and steering. Now you can actually hook this system up to any form of mechanical propulsion you want, as long as you can drive it by turning a shaft. Wheels? Tracks? Hydrojets? All perfectly fine, just hook them to the drive shaft.

However none of those work in space. You could still run a nuclear reactor, but it would be a bad idea, because it is basically impossible to vent heat as fast as the reactor produces it. In a normal steam turbine you want the water to cool down, then cycle it back into the reactor to heat again. In space, there really isn't anywhere for that heat to go, once something gets hot it kind of just stays hot for a very long time. Second problem is that there is nothing really that can make you move by just turning a drive shaft. All of those forms of movement require something to push against to move the vehicle forward, it can push against water, air, or the ground, but it can't push against nothing.

So any form of nuclear engine on a space ship has to use a fundamentally different principle. The one being discussed here basically focuses the heat on a small amount of Hydrogen, and then shoots that hydrogen at the speed of Plaid. Which makes the vehicle go in the opposite direction of the junk of hydrogen you just yeeted into the cosmos. Basically it is traveling by shooting a radioactive gun in one direction so the recoil knocks you in the direction you want to go. You need fuel to run the reactor, and "Ammo" to keep shooting until you get to the desired speed (And you need the same amount of ammo if you ever want to slow down again)

While it is more difficult in a near vacuum, having to do without a medium for conductive or convective heath exchange, it is entirely possible to run a variety of nuclear reactor in space for power generation, as heath can be shed trough radiation : it involves massive radiators shedding IR.

Its been very seriously used and researched for a variety of space exploration programs :

Nuclear power in space

A number of probes used radioisotope thermoelectric generator over the history of Space exploration. And NASA was/is developing the Advanced Stirling radioisotope generator, the safe affordable fission engine, and the Kilopower project.

In the early 2000s NASA even researched Project Prometheus, which would have used a nuclear reactor inspired by submarines ones coupled with massive radiators to power the ion thruster of a an exploration vessel to the Jovian system :

[Thekri]

While it is more difficult in a near vacuum, having to do without a medium for conductive or convective heath exchange, it is entirely possible to run a variety of nuclear reactor in space for power generation, as heath can be shed trough radiation : it involves massive radiators shedding IR.

Its been very seriously used and researched for a variety of space exploration programs :

Nuclear power in space

A number of probes used radioisotope thermoelectric generator over the history of Space exploration. And NASA was/is developing the Advanced Stirling radioisotope generator, the safe affordable fission engine, and the Kilopower project.

In the early 2000s NASA even researched Project Prometheus, which would have used a nuclear reactor inspired by submarines ones coupled with massive radiators to power the ion thruster of a an exploration vessel to the Jovian system :

(IMG SNIP)

True. I was vastly oversimplifying to explain basic principles. There are a lot of cool options that we have theorized. The point was that space is really, really different then earth, and you can't just stick a WWII Battleship in orbit and call it a spaceship now. Except in Japan.

[plz delete account]

the flat earthers must be feeling damn special as I have seen here. No space, no nothing. where do they think they live?
are we in an aquarium? I am off to google to see what they propose.

I swear these have the same brain cells as dumb fucks saying then send the rocket to the sun at night when it is cool .

bloody hell ffs. WHen humanity moves across the stars, let these rot here.

Rocket scientist here. The send the rocket to the sun at night thing started as a joke in the aerospace industry. It still is, only a few low IQ individuals have decided to take it literally, and not as the ironic sarcasm it is.

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Bloody hell, thank you! In terms of heat venting, is it not easier in space if the engine is somehow exposed or fitted with some heat transfer as space its cold?

Totally unrelated. Could magnetic fields push an object if great enough? If you could replicate earths magnetic field on a spaceship, you could use that as energy to propel? Maybe one day we will know about "bending" space and gravity to use that as the source of transportation.

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Ah thanks. When it comes to these topics I have no clue, fascinated by all things space/engineering but don't know much of the actual science.

Magnetism is already used to propel objects. Maglevs and electromagnets are already in use, and Mass Drivers could be used to achieve orbit, or even send stuff back to Earth without needing to eject plasma of various kinds out the back. To propel spacecraft though... probably not, unless you include Hal effect thrusters.