# Why wouldn't an "atomic rocket" (as in "Rocket Ship Galileo") work? **URL:** \ **Category:** Factual Questions\ **Created:** [December 9, 2007, 8:19pm UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411 "2007-12-09T20:19:01Z")\ **Posts on this page:** 12\ **Page:** 2
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [December 11, 2007, 3:49pm UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/21 "2007-12-11T15:49:54Z")
Here’s an atomic-powered cruise missile: [http://www.merkle.com/pluto/pluto.html](http://www.merkle.com/pluto/pluto.html) ---
**Author:** ![t-mobileguy](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@t-mobileguy](https://boards.straightdope.com/u/t-mobileguy)\ **Post date:** [December 12, 2007, 12:51am UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/22 "2007-12-12T00:51:56Z")
Don’t some subs use a nuclear engine? What would be the problem with basically putting a sub in space (I mean not really putting a sub in space, but using the infrastructure of a submarine). I know it wouldn’t work but I’m not sure of the why. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [December 12, 2007, 1:13am UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/23 "2007-12-12T01:13:06Z")
[QUOTE=t-mobileguy] Don’t some subs use a nuclear engine? What would be the problem with basically putting a sub in space (I mean not really putting a sub in space, but using the infrastructure of a submarine). I know it wouldn’t work but I’m not sure of the why. [/QUOTE] Since a sub’s nuclear reactor provides energy to turn the propeller, I don’t think that would accomplish much. 😛 If you mean why can’t the powerplant from a nuclear sub be adapted as a rocket engine, it’s because typical nuclear power plants don’t operate at anywhere near the temperature useful for heating propellent. People think of nuclear reactors as incredibly powerful, yet while they can put out energy for far longer than any equivalent weight of chemical fuel can, they actually aren’t that impressive when measured in terms of a _power_ (energy rate per second) to weight ratio. An ordinary chemical rocket engine is stupendously powerful for the brief period it’s fuel lasts. ---
**Author:** ![t-mobileguy](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@t-mobileguy](https://boards.straightdope.com/u/t-mobileguy)\ **Post date:** [December 12, 2007, 2:13am UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/24 "2007-12-12T02:13:15Z")
[QUOTE=Lumpy] Since a sub’s nuclear reactor provides energy to turn the propeller, I don’t think that would accomplish much. 😛 . [/QUOTE] yeah? bet you never took [Aether](http://en.wikipedia.org/wiki/Aether_theories) into consideration 😉 [QUOTE=Lumpy] People think of nuclear reactors as incredibly powerful, yet while they can put out energy for far longer than any equivalent weight of chemical fuel can, they actually aren’t that impressive when measured in terms of a _power_ (energy rate per second) to weight ratio. An ordinary chemical rocket engine is stupendously powerful for the brief period it’s fuel lasts. [/QUOTE] So how much of a power difference are we talking about? Consider me one of those people who thought nuclear reactors= lotsa power. Is it something that could be scaled up or are we talking about 2 totally different kinds of power plants? ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [December 12, 2007, 8:17am UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/25 "2007-12-12T08:17:23Z")
[QUOTE=BrainGlutton] And storing your reaction mass in metal-ingot form would save on space, compared to liquid oxygen or whatever, wouldn’t it? Yet no space program has ever used such a thing, AFAIK; every spaceship uses chemical propellants. [/QUOTE] How about using [Teflon](http://www.fathom.com/course/21701743/session5.html) as a propellant, slick idea, ain`t it? :dubious: > [@](#): > > PPTs use solid Teflon propellant to deliver specific impulses in the 900-1,200 s range and very low, precise impulse “bits” (10-1,000 μNs) at low average power (\< 1 to 100 W). While PPTs are inherently inefficient (ηt ~5%), their simplicity and low impulse bits provide them with a niche for space propulsion; for example, precision-flying of a spacecraft constellation. ---
**Author:** ![foolscap](https://avatars.discourse-cdn.com/v4/letter/f/e9a140/32.png) [@foolscap](https://boards.straightdope.com/u/foolscap)\ **Post date:** [November 9, 2009, 1:40am UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/26 "2009-11-09T01:40:59Z")
I can’t see why DUMBO (an up rated NERVA) has not been mentioned. It has the thrust to lift off from the surface, unlike the nerva.😃 ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [November 9, 2009, 4:21pm UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/27 "2009-11-09T16:21:39Z")
Impulse drives in _Star Trek_ use deuterium as reaction mass, IIRC. ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [November 9, 2009, 4:36pm UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/28 "2009-11-09T16:36:06Z")
> [@t-mobileguy](#): > > Don’t some subs use a nuclear engine? What would be the problem with basically putting a sub in space (I mean not really putting a sub in space, but using the infrastructure of a submarine). > > I know it wouldn’t work but I’m not sure of the why. It seems kinda funny in how we actually use nuclear reactors. All they are really used for is as a really hot fire. We use them to boil water into steam. We use that steam to turn the blades in a turbine, to either generate electricity, or spin a propellor. In Scifi, the seemingly magical power plants don’t seem to have this steam component to them. You have to figure out how your going to translate either this steam or electricity into a propulsive force. Venting the steam is well within modern tech, I think, but you are going to need a crap ton of water as reaction mass. Water is pretty heavy. You are going to be pretty limited in how much “burn time” you get out of that. Using the electricty to power some other process… I have no ideas there. ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [November 9, 2009, 4:44pm UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/29 "2009-11-09T16:44:40Z")
> [@t-mobileguy](#): > > So how much of a power difference are we talking about? Consider me one of those people who thought nuclear reactors= lotsa power. Is it something that could be scaled up or are we talking about 2 totally different kinds of power plants? The nuclear powerplants used in civilian powerplants, aircraft carriers and submarines do nothing more than make steam for turbines. Essentially the same thing that you could do with coal or oil. It’s just that, instead of being burned and needing to be constantly replinished, nuclear fuel lasts for years at a time. You could use steam to propel a spacecraft but you’d have to carry all that heavy water along with you. ---
**Author:** ![pan1](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pan1](https://boards.straightdope.com/u/pan1)\ **Post date:** [November 9, 2009, 5:11pm UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/30 "2009-11-09T17:11:20Z")
There’s absolutely no reason to believe that a Nuclear powered space ship is not possible or even unlikely. Nucler powered propulsion is ideal for long distance space travel. It’s cheap, light and there’s no difficulty in storing the waste. The tricky bit is that a nuclear powered engine won’t get you off a planet. There’s no current propulsion device capable of using Nuclear Power to launch a vehicle into space. The only engine with that capacity that I know of would be a rocket. Once in space, ion propulsion is cheap, but it takes a long time to get a ship with any mass up to speed. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [November 9, 2009, 5:49pm UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/31 "2009-11-09T17:49:32Z")
> [@mlees](#): > > It seems kinda funny in how we actually use nuclear reactors. All they are really used for is as a really hot fire. We use them to boil water into steam. We use that steam to turn the blades in a turbine, to either generate electricity, or spin a propellor. The steam cycle is ancient technology, but then so is the wheel. Ya find something good, you stick with it. > [@](#): > > Using the electricty to power some other process… I have no ideas there. [Ion rockets](http://en.wikipedia.org/wiki/Ion_rocket) will take you places. ---
**Author:** ![Alex\_Dubinsky](https://avatars.discourse-cdn.com/v4/letter/a/dbc845/32.png) [@Alex\_Dubinsky](https://boards.straightdope.com/u/Alex_Dubinsky)\ **Post date:** [November 10, 2009, 3:09am UTC](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411/32 "2009-11-10T03:09:39Z")
Firstly, good job on the zombifying. But since the first discussion didn’t last too long, prob no harm in continuing it. The salt-water rockets someone mentioned are pretty darn cool. They bypass the problem Lumpy mentioned, that although nuclear power can heat fuel to a bizzilion degrees, your pipes and nozzles are the limiting factor, and chemical rockets are already hitting the limits. The salt-water nuclear rockets essentially create a continuous nuclear explosion, outside of the spacecraft. It is sort of like Orion, except you don’t need the giant ridiculous shock absorber. It’s continuous and works on a smaller scale. It is also extremely simple. Mix water and plutonium. Store it in a special vessel that keeps it from going critical. Squirt it out behind you and watch it go boom. The temperatures achievable are huge, so you can get both a massive thrust and great propellant efficiency. It’d lift you off a planet, if you felt like doing that. [Previous page](https://boards.straightdope.com/t/why-wouldnt-an-atomic-rocket-as-in-rocket-ship-galileo-work/429411.md?page=1)