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Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

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Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#51

Post by grkvlt »

berntb wrote: post #38
andygates wrote: post #33

Earlier quoted context omitted.

> nuclear is unfashionable at the moment It's more than that - this isn't just hippies, it's every major power on the planet. To fly Orion you have to put hundreds of nuclear explosives in orbit and pinky-swear that you're not going to use them to obliterate your enemies. Nobody is going to accept that. Orion's a fun paper rocket but will never be more. Engineers and they "yay nukes!" crowd will drag it out every cou…

If you read the book (by Freeman Dyson's son) or even the wikipedia page, you'd know the bombs were quite specialized. And it would certainly be possible to allow some verification (the trigger would not need inspection, that would probably be the really sensitive part, from a technology secrets point of view). [Edit: The bombs would be directed, throwing light weight molecules up against the pusher plate.] Also, the…

Any mechanism that can propel a starship to 0.13c is going to make your day unpleasant if it is pointed at things you have a particular fondness for. Favourite pets, cities, aircraft carriers, that sort of thing.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#52

Post by grkvlt »

XorNot wrote: post #45
IndianAstronaut wrote: post #29

Earlier quoted context omitted.

We are a long ways from becoming space faring. For the cost of sending one human to Mars, we could send ten rovers to Mars.

Not if Elon Musk gets his way. If the cost profile works out, sending a human will be cheaper then sending a robot.

Even then, we can still send rovers more cost effectively than people! You can throw away the life support mechanisms, and so on, and get 550 tons of pure mars rover in your interplanetary transport. At ~800kg for a curiosity-level rover that gives about 600 rovers, instead of 100 people.

What to do with your 600 curiosity rovers on Mars is left as an exercise...

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#53

Post by snrplfth »

simonh wrote: post #43
wyager wrote: post #26

Earlier quoted context omitted.

>This kind of nuclear research is, thankfully, over. Nuclear pulse propulsion is the only currently viable technology that could be used to make humans an interstellar species. It would also allow us to practically ship up enough materials to build self-sustaining habitats in near space. It is extremely unfortunate that this kind of research is over. Fun fact: the background radiation levels introduced by nuclear pro…

On the other hand if we'd gone all-in on nuclear pulse launchers, there would have been no incentive for companies like SpaceX and Blue Origin to develop reusable conventional rockets which will hopefully achieve the same result at lower environmental and perhaps also financial cost.

Even if you had effective nuclear pulse propulsion, you'd still need reusable chemical launchers to get them off the surface of Earth. Nuclear pulse engines are generally not something that you start up inside an atmosphere, for both safety and efficiency reasons.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#54

Post by maxerickson »

DennisP wrote: post #47
jessriedel wrote: post #46

Earlier quoted context omitted.

> To fly Orion you have to put hundreds of nuclear explosives in orbit and pinky-swear that you're not going to use them to obliterate your enemies. To reiterate berntb's point: Every nation who has the ability to do this already has ICBMs that can deliver nukes anywhere on the planet in 20 minutes. So what difference does this make?

True, but we still have a treaty that prohibits bombs in orbit, because they'd reduce the warning time enough to threaten deterrence. Maybe one day we can launch Orion from Mars.

Drive it to Earth, have lots of bombs left.

From a strategic point of view, what's the difference between building on Mars and building it in orbit? Obviously there is a difference because the hostile faction has to seize control of it and move it to Earth, but once they do that, the calculation becomes the same. Do you commit to obliterating them the second they start moving it to Earth?

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#55

Post by adrianN »

Pinckney wrote: post #48
XorNot wrote: post #45

Earlier quoted context omitted.

Not if Elon Musk gets his way. If the cost profile works out, sending a human will be cheaper then sending a robot.

His cost estimates depend on hundreds of thousands of people signing up, to diffuse R&D costs. That's dubious. Historically, colonists are self-interested. Typically they want to become rich, or they want to escape poverty or persecution. (Typically they're also poorly informed about just how dangerous their new life will be, and how much wealth they can expect to find, but in this age we shouldn't expect that to las…

Giving a generation of people who grew up with science fiction as part of their daily lives the opportunity to move to a different planet is also unprecedented.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#56

Post by masklinn »

maxerickson wrote: post #54
DennisP wrote: post #47

Earlier quoted context omitted.

True, but we still have a treaty that prohibits bombs in orbit, because they'd reduce the warning time enough to threaten deterrence. Maybe one day we can launch Orion from Mars.

Drive it to Earth, have lots of bombs left. From a strategic point of view, what's the difference between building on Mars and building it in orbit? Obviously there is a difference because the hostile faction has to seize control of it and move it to Earth, but once they do that, the calculation becomes the same. Do you commit to obliterating them the second they start moving it to Earth?

Best case scenario, Mars is 55 million kilometres from earth. Even using a ridiculous engine going full blast the whole way (in which case your payload will probably disintegrate when it hits the atmosphere) you won't get the transfer time under a month. If you want to actually deliver your payload in a useful manner you'll need twice that at the very least. 2+ months is a long lead time, and the engine you'll need will make the craft impossible to miss.

What's the difference to building it in orbit? Building it in earth orbit you're dropping it from under 500km and your assembly makes 10~20 orbits a day, you can deliver it quickly at pretty much any time.

The former allows countermeasure, the latter not really.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#57

Post by berntb »

grkvlt wrote: post #51
berntb wrote: post #38

Earlier quoted context omitted.

If you read the book (by Freeman Dyson's son) or even the wikipedia page, you'd know the bombs were quite specialized. And it would certainly be possible to allow some verification (the trigger would not need inspection, that would probably be the really sensitive part, from a technology secrets point of view). [Edit: The bombs would be directed, throwing light weight molecules up against the pusher plate.] Also, the…

Any mechanism that can propel a starship to 0.13c is going to make your day unpleasant if it is pointed at things you have a particular fondness for. Favourite pets, cities, aircraft carriers, that sort of thing.

It is a theoretical "can". :-) It will be a long time before anyone use a fraction of C inside the solar system.

Interstellar flight is a problem after we have gotten to a reasonable cost/kg for both launching from the Earth and for interplanetary travel.

I doubt there will be a pressing need for getting close to even 100 km/s in the inner solar system for decades. (Yes yes, "640K is enough for anyone". :-) )

(Consider: An AU is 150 million km. 100 km/second means 8.64 million km a day; 2 AUs in 35 days! Then you have to lower the speed, even more energy.)

Launching an Orion from the ground is probably not realistic after the 1960s either. It would have the problem with bombs and EMP killing satellites. I've seen suggestions to coast through the sensitive zone without using bombs, but haven't seen any discussion about how many Gs it would mean...

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#58

Post by madaxe_again »

arethuza wrote: post #42
berntb wrote: post #38

Earlier quoted context omitted.

If you read the book (by Freeman Dyson's son) or even the wikipedia page, you'd know the bombs were quite specialized. And it would certainly be possible to allow some verification (the trigger would not need inspection, that would probably be the really sensitive part, from a technology secrets point of view). [Edit: The bombs would be directed, throwing light weight molecules up against the pusher plate.] Also, the…

The "directed" bomb designs used tungsten - in "The Curve of Binding Energy" I seem to remember there is a comment that they were spectacularly good at digging tunnels but I don't know if that was a theoretical prediction or an empirical result.

If you consider that it was contemporaneous with plowshare, that makes sense - likely a degree of shared research.

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#59

Post by Tuna-Fish »

luckystarr wrote: post #41

Nuclear salt-water rockets! https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket Powerful, fast, intriguing and disgusting. :)

Project orion has the name recognition, but nuclear salt water rockets would just be a much better use of the same amount of fissiles. Maybe we should start reposting the wikipedia link every month until people remember mr. Zubrin's creations more than project Orion?

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#60

Post by api »

andygates wrote: post #33
sillysaurus3 wrote: post #2

Happy to see this getting some attention. It's seemed like one of the only viable propulsion methods for interstellar purposes, though nuclear is unfashionable at the moment. I remember seeing a chart showing that it was possible to reach other stars using a technique like this. Unfortunately the problem is slowing down. You could get there, but you'd be going too fast to stop. And since the more fuel you carry, the…

> nuclear is unfashionable at the moment It's more than that - this isn't just hippies, it's every major power on the planet. To fly Orion you have to put hundreds of nuclear explosives in orbit and pinky-swear that you're not going to use them to obliterate your enemies. Nobody is going to accept that. Orion's a fun paper rocket but will never be more. Engineers and they "yay nukes!" crowd will drag it out every cou…

Even worse: the EMP from an Orion launch would fry a lot of satellites. It's not a practical design for use anywhere near... anything.

You could launch one from the far side of the Moon, but if you have that kind of space presence there are better engine designs. Some have been posted elsewhere in this thread.

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