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Project Orion

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Re: Project Orion

#21

Post by ianburrell »

nwah1 wrote: post #17
ianburrell wrote: post #12

Project Orion is a really bad idea. I guess it could be a good idea in specific situation where have to get a lot of mass off the planet and don't care about the effects. Problem one is that detonating a series of nuclear bombs in the atmosphere. The first couple are close to the ground and produce local fallout, the higher ones produce global fallout. Problem two is that detonating nuclear bombs in space causes EMP.…

Launching from lunar orbit would obviate EMP and terrestrial radiation concerns. But those are the least of the concerns.

The problem with that is Orion is that it is heavy. It only makes sense when launching the whole thing from the ground. Orion has been proposed for interplanetary propulsion since it is pretty efficient. But would need to be convertible from ground-launch to space propulsion. Nuclear rockets are pretty good and safer to launch.

The other problem is that nuclear weapons are expensive. Something like Davy Crockett is 2kg of plutonium, and mid-sized Orion would use 800 to get to orbit. Plutonium is $4000/g which means $6.4 billion to launch Orion. Orion that puts 1600t in orbit. Or 10 Starships which is less as disposable rockets and way less if reuasable.

Re: Project Orion

#22

Post by whatshisface »

ShakataGaNai wrote: post #20

There is a Kerbal Space Program mod [1] that adds this to the game. It is hysterically fun to use because it is insanely unbalanced compared to normal space flight requirements. Want to change your orbit 180deg and fly backwards? No problem. Goto any planet the "direct" route? Sure, why not. Take off from the launch pad so fast you'll think the game broke? Not a problem - The Kerbal's don't worry about a little fallo…

Based on the amount of time a Kerbal can survive orbiting the sun in their barely-shielded capsules, I am inclined to think that they are immune to radiation damage, like tardigrades.

Re: Project Orion

#23

Post by adrenvi »

ShakataGaNai wrote: post #20

There is a Kerbal Space Program mod [1] that adds this to the game. It is hysterically fun to use because it is insanely unbalanced compared to normal space flight requirements. Want to change your orbit 180deg and fly backwards? No problem. Goto any planet the "direct" route? Sure, why not. Take off from the launch pad so fast you'll think the game broke? Not a problem - The Kerbal's don't worry about a little fallo…

Project Orion uses a pusher plate mounted on giant springs to spread out the force of each explosion. If the system is designed correctly it should result in constant acceleration.

Re: Project Orion

#24

Post by tomatotomato37 »

ianburrell wrote: post #12

Project Orion is a really bad idea. I guess it could be a good idea in specific situation where have to get a lot of mass off the planet and don't care about the effects. Problem one is that detonating a series of nuclear bombs in the atmosphere. The first couple are close to the ground and produce local fallout, the higher ones produce global fallout. Problem two is that detonating nuclear bombs in space causes EMP.…

Not as "spicy" an idea as the Nuclear saltwater rocket however, which instead of discrete bombs involves dissolving a load of bomb-grade fissiles into water and then ejecting them out a conventional rocket engine, with the idea the solution goes critical somewhere in the vincinity of the exhaust nozzle. Now if you're thinking "Does that replace singular discrete nuclear explosions with a continual nuclear explosion shrouded in an expanding cloud of radioactive superheated steam?", the answer is yes, yes it does.

Weirdest thing is the design doesn't actually have as much potential ISP as a pulsed detonation system like an Orion, despite being a bonafide torchship. Go figure

https://en.m.wikipedia.org/wiki/Nuclear_salt-water_rocket

Re: Project Orion

#25

Post by nyrath »

AnimalMuppet wrote: post #15
marktangotango wrote: post #8

There was a classic science fiction story with a twist on this idea; a low tech species was about to be discovered by a more advanced species. And according to the rules of the more advanced species, any planet that wasn't capable of space travel would become a client or vassal, and a planet with space travel would be seen as a peer. The protagonist built a pusher style rocket using an explosive, and launched the lig…

"King David's Spaceship". I believe it was by Niven, but I'm not sure.

"King David's Spaceship" aka "A Spaceship For The King" by Jerry Pournelle

Re: Project Orion

#26

Post by jerf »

perihelions wrote: post #19
st_goliath wrote: post #6

An other quite interesting concept (also a little less "out there" and actually, successfully tested) is the NERVA engine, also linked at the bottom of the article[1]. It uses a nuclear reactor to heat up a single propellant (liquid hydrogen) which then rapidly expands as it goes out the nozzle at the end, resulting in quite high specific impulse and is more efficient than a chemical rocket. If we want to go really f…

There's one more: the boring idea of combining a closed, electric-generating nuclear fission system with an (electric-powered) ion engine. Both components being flight tested and not crazy.

That doesn't sound like something that could get you off of the Earth.

It's probably a great choice for once you're already in space, where being able to apply even very small thrusts nearly-continuously really adds up.

Re: Project Orion

#27

Post by philipkglass »

ianburrell wrote: post #21
nwah1 wrote: post #17

Earlier quoted context omitted.

Launching from lunar orbit would obviate EMP and terrestrial radiation concerns. But those are the least of the concerns.

The problem with that is Orion is that it is heavy. It only makes sense when launching the whole thing from the ground. Orion has been proposed for interplanetary propulsion since it is pretty efficient. But would need to be convertible from ground-launch to space propulsion. Nuclear rockets are pretty good and safer to launch. The other problem is that nuclear weapons are expensive. Something like Davy Crockett is 2…

In 1965 the Atomic Energy Commission put the cost of plutonium 239 at $10/gram, which by simple consumer price indexing (only a rough guide, admittedly) would make it $96/gram today.

See Table I in this publication "Values In Spent Fuel From Power Reactors":

https://www.osti.gov/servlets/purl/4618921

At $96 per gram instead of $4000, that's a much more attractive $154 million to put 1600 tons in orbit. Uranium enrichment costs have fallen greatly since the 1960s as centrifuges have replaced gaseous diffusion, so uranium-fueled units would probably cost less (despite the greater mass of uranium required).

I'd say that the main modern problems of a terrestrially launched Orion are treaty violations and giving a plausible cover for nations to again pursue developing "peaceful" nuclear explosives.

Re: Project Orion

#28

Post by mpweiher »

marktangotango wrote: post #8

There was a classic science fiction story with a twist on this idea; a low tech species was about to be discovered by a more advanced species. And according to the rules of the more advanced species, any planet that wasn't capable of space travel would become a client or vassal, and a planet with space travel would be seen as a peer. The protagonist built a pusher style rocket using an explosive, and launched the lig…

> Footfall by Niven and Pournelle which featured launching the USS Missouri into orbit on an Orion style pusher

Yes, there was an Orion. No they didn't launch the USS Missouri. The ship was called Michael and featured, among other crazy weaponry, X-Ray lasers of the SDI type, i.e. some material (ruby?) pumped by a nuke. The nuke would destroy the material, but in the process get it to lase X-Rays. Heck, if you're using nukes for propulsion, might as well do that as well.

Maybe they repurposed the guns for something?

I distinctly remember some dialogue that there was some fairly rough welding of thick steel plates going on, none of the ultra-fine tolerances of traditional rocket engineering.

Re: Project Orion

#29

Post by tppiotrowski »

There is also a book called Project Orion: The True Story of the Atomic Spaceship. It's still sitting on my shelf, but I don't remember it being a particularly inspiring read because it was tailored towards interstellar travel when we hadn't even reached Mars yet.

Re: Project Orion

#30

Post by smilespray »

didericis wrote: post #18
antondd wrote: post #5

Earlier quoted context omitted.

Interstellar nuclear-powered transport (1968) - https://news.ycombinator.com/item?id=28132756 - Aug 2021 (34 comments) There are a few more, under different titles. I remember reading Dyson’s autobiography a couple of years ago and he mentioned his involvement in the research. Absolutely amazing stuff.

There’s a great BBC documentary on this called “To Mars by a Bomb”, highly recommend it. Was one of my first introductions to Freeman Dyson, ended up reading his autobiography as well. Was a remarkable man, and one of my favorite people to listen to.

It's on YouTube, and I second this recommendation.

https://youtu.be/xYoLcJuBtOw

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