6 ms·

Project Orion (nuclear propulsion)

32 points by shaaaaawn 12y ago

Maakuth 12y ago
See also Tintin's moon rocket's propulsion: https://en.wikipedia.org/wiki/Explorers_on_the_Moon#Rocket_engine https://en.wikipedia.org/wiki/Explorers_on_the_Moon#Rocket_e... and https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA
- TeMPOraL 12y ago
  The thing that surprised me when reading about NERVA is that - according to Wiki article - space race partially died out because the US Government explicitly decided they're tired with it and there are better ways of spending money than going to Mars.
- Symmetry 12y ago
  People have come up with a lot of ways to use nuclear energy to power rockets. Most are less crazy than Orion but one, the nuclear saltwater engine, even more so. Here's a good source of info. http://www.projectrho.com/public_html/rocket/enginelist.php http://www.projectrho.com/public_html/rocket/enginelist.php
4ad 12y ago
George Dyson (son of Freeman Dyson) speaks about project Orion here: https://www.ted.com/talks/george_dyson_on_project_orion https://www.ted.com/talks/george_dyson_on_project_orion
Freaky 12y ago
Medusa seems like a better approach, since it doesn't require detonating as close to the spacecraft and can forgo the big heavy pusher plate: http://www.centauri-dreams.org/?p=23754 http://www.centauri-dreams.org/?p=23754
Symmetry 12y ago
One interesting bit that was in George Dyson's book but not the Wikipedia article (that I saw) was that for sustained thrust the idea is to keep the pusher plate in resonance with the atomic bomb detonations. You use a half sized bomb to get things going then detonate full sized bombs when the plate is heading away from the main compartment. The real problem with an Orion drive is launching the thing. Simple atomic bombs don't generate that much fallout (relatively speaking) by themselves. There wasn't any noticeable fallout in Japan after the explosions at Hiroshima and Nagasaki. The big source of dangerous fallout is when neutrons from an atomic explosion are captured by nearby materials and transmute them into radioactive ones. For an explosion high up the surrounding hydrogen, oxygen, carbon, and nitrogen don't turn into anything nasty. But if the explosion is near the ground there are all sorts of horrible things that can easily be produced. If you wanted to launch an Orion into space with relatively little fallout you would need to either have boosters that lift it a kilometer up before it engages it's main drive or launch it a large area you've covered completely with graphite (see again carbon-14 not being dangerous). The reason that the bombs the US and USSR have stockpiled produce so much fallout is their third stages. First you have a regular atomic bomb that sets of a fusion explosion. But surrounding these is the bomb's shell made out of the Uranium-238 that was left over after the process of separating out the uranium-235. You can't create a chain reaction with U238 but it does fission and produce a lot of energy (but no neutrons) when you hit it with a neutron and about half the energy of a bomb can come from the case. You can easily make the case out of lead instead and have a relatively clean nuclear bomb but the military considered the fallout a feature rather than a bug. In the end project Orion was a cool idea and not so crazy as you might think at first. But I'd much rather people use conventional nuclear thermal rockets where you use a normal reactor to heat a bunch of propellant. It doesn't offer the same combination of power and efficiency as Orion but if you switch your reactor to generate power and run a VASIMR then you can have at least one or the other and you don't have to deal with any fallout. EDIT: Oh, there's also the problem of EMP as Orion passes through the ionosphere. The bombs it uses are much smaller than an H bomb so they probably won't cause problems but nobody knows for sure.
- mrfusion 12y ago
  You could always construct it in orbit too? That might be the safest option?
Yizahi 12y ago
I recommend to read this story by Charles Stross "A Tall Tail": http://www.tor.com/stories/2012/07/a-tall-tail http://www.tor.com/stories/2012/07/a-tall-tail
alcima 12y ago
People forget that Kennedy's actual request was: First - "before this decade is out, is landing a man on the moon and returning him safely to earth" Second - "acceleate development of the Rover nuclear rocket" Third - "accelerate the use of satellites for world wide communications" Fourth - "a satellite system for world wide weather observation" Too bad we only got 3 out of 4 and are still stuck with cans of flammable mud.

32 points by shaaaaawn 12y ago

See also Tintin's moon rocket's propulsion: https://en.wikipedia.org/wiki/Explorers_on_the_Moon#Rocket_engine https://en.wikipedia.org/wiki/Explorers_on_the_Moon#Rocket_e... and https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA

TeMPOraL 12y ago
The thing that surprised me when reading about NERVA is that - according to Wiki article - space race partially died out because the US Government explicitly decided they're tired with it and there are better ways of spending money than going to Mars.
Symmetry 12y ago
People have come up with a lot of ways to use nuclear energy to power rockets. Most are less crazy than Orion but one, the nuclear saltwater engine, even more so. Here's a good source of info. http://www.projectrho.com/public_html/rocket/enginelist.php http://www.projectrho.com/public_html/rocket/enginelist.php

4ad 12y ago

George Dyson (son of Freeman Dyson) speaks about project Orion here: https://www.ted.com/talks/george_dyson_on_project_orion https://www.ted.com/talks/george_dyson_on_project_orion

Freaky 12y ago

Medusa seems like a better approach, since it doesn't require detonating as close to the spacecraft and can forgo the big heavy pusher plate: http://www.centauri-dreams.org/?p=23754 http://www.centauri-dreams.org/?p=23754

Symmetry 12y ago

One interesting bit that was in George Dyson's book but not the Wikipedia article (that I saw) was that for sustained thrust the idea is to keep the pusher plate in resonance with the atomic bomb detonations. You use a half sized bomb to get things going then detonate full sized bombs when the plate is heading away from the main compartment. The real problem with an Orion drive is launching the thing. Simple atomic bombs don't generate that much fallout (relatively speaking) by themselves. There wasn't any noticeable fallout in Japan after the explosions at Hiroshima and Nagasaki. The big source of dangerous fallout is when neutrons from an atomic explosion are captured by nearby materials and transmute them into radioactive ones. For an explosion high up the surrounding hydrogen, oxygen, carbon, and nitrogen don't turn into anything nasty. But if the explosion is near the ground there are all sorts of horrible things that can easily be produced. If you wanted to launch an Orion into space with relatively little fallout you would need to either have boosters that lift it a kilometer up before it engages it's main drive or launch it a large area you've covered completely with graphite (see again carbon-14 not being dangerous). The reason that the bombs the US and USSR have stockpiled produce so much fallout is their third stages. First you have a regular atomic bomb that sets of a fusion explosion. But surrounding these is the bomb's shell made out of the Uranium-238 that was left over after the process of separating out the uranium-235. You can't create a chain reaction with U238 but it does fission and produce a lot of energy (but no neutrons) when you hit it with a neutron and about half the energy of a bomb can come from the case. You can easily make the case out of lead instead and have a relatively clean nuclear bomb but the military considered the fallout a feature rather than a bug. In the end project Orion was a cool idea and not so crazy as you might think at first. But I'd much rather people use conventional nuclear thermal rockets where you use a normal reactor to heat a bunch of propellant. It doesn't offer the same combination of power and efficiency as Orion but if you switch your reactor to generate power and run a VASIMR then you can have at least one or the other and you don't have to deal with any fallout. EDIT: Oh, there's also the problem of EMP as Orion passes through the ionosphere. The bombs it uses are much smaller than an H bomb so they probably won't cause problems but nobody knows for sure.

mrfusion 12y ago
You could always construct it in orbit too? That might be the safest option?

Yizahi 12y ago

I recommend to read this story by Charles Stross "A Tall Tail": http://www.tor.com/stories/2012/07/a-tall-tail http://www.tor.com/stories/2012/07/a-tall-tail

alcima 12y ago

People forget that Kennedy's actual request was: First - "before this decade is out, is landing a man on the moon and returning him safely to earth" Second - "acceleate development of the Rover nuclear rocket" Third - "accelerate the use of satellites for world wide communications" Fourth - "a satellite system for world wide weather observation" Too bad we only got 3 out of 4 and are still stuck with cans of flammable mud.