Project Orion/Daedalus/Longshot

[caveman1917]

I was reading up on these hypothetical nuclear propulsed spacecraft, and it seems they should be within 'relatively' easy reach. So i was wondering, why aren't we building one right now? What are our prospects on this, near term?

These al seem to be thought up in the 60s-70s, perhaps we have even better designs right now which are feasible for say around 0.1c?

http://en.wikipedia.org/wiki/Project..._propulsion%29

http://en.wikipedia.org/wiki/Project_Daedalus

http://en.wikipedia.org/wiki/Project_Longshot

[NEOWatcher]

So i was wondering, why aren't we building one right now?

Nuclear space treaties, and public fears of launching nuclear devices.

These al seem to be thought up in the 60s-70s...

When the public was still enchanted with the abilities of nuclear energy and before nuclear operations were percieved as dangerous.

[JustAFriend]

Did you see the crowd of protesters on the news when they launched Cassini to Saturn with a small thermal nuclear power plant????

If you read the Project Orion book they talk about how they worked out big reductions in the amount of fallout in the later versions, but the anti-nuke crowd didn't even want encapsulated power plants or launching the components into orbit to let the Orions launch from there.

[IsaacKuo]

I was reading up on these hypothetical nuclear propulsed spacecraft, and it seems they should be within 'relatively' easy reach. So i was wondering, why aren't we building one right now? What are our prospects on this, near term?

None of them are within "relatively" easy reach.

Project Daedalus and Project Longshot require inertial confinement fusion technology, which is still "20 years away", and will still be "20 years away" for the forseeable future.

Project Orion requires large numbers of nuclear bombs, which are very expensive (very expensive times large numbers equals exceedingly expensive). It also requires wishful thinking about the engineering of a pusher plate to survive the battering from the nuclear bombs, as well as wishful thinking about how much money and time it would cost to develop.

These al seem to be thought up in the 60s-70s, perhaps we have even better designs right now which are feasible for say around 0.1c?

Yes, there are better ideas now. For example, Geoffrey Landis's relativistic particle beam propulsion would be more efficient, wouldn't require expensive nuclear fuel, would use mostly known technology, and would be capable of much higher speeds.

[caveman1917]

Did you see the crowd of protesters on the news when they launched Cassini to Saturn with a small thermal nuclear power plant????

If you read the Project Orion book they talk about how they worked out big reductions in the amount of fallout in the later versions, but the anti-nuke crowd didn't even want encapsulated power plants or launching the components into orbit to let the Orions launch from there.

Yes, they just always do that, don't they?

Project Orion requires large numbers of nuclear bombs, which are very expensive (very expensive times large numbers equals exceedingly expensive). It also requires wishful thinking about the engineering of a pusher plate to survive the battering from the nuclear bombs, as well as wishful thinking about how much money and time it would cost to develop.

Would we still require a pusher plate for a non manned mission?

Yes, there are better ideas now. For example, Geoffrey Landis's relativistic particle beam propulsion would be more efficient, wouldn't require expensive nuclear fuel, would use mostly known technology, and would be capable of much higher speeds.

Do you have a link with more information on this?
Would this not limit us to flyby missions only?

[IsaacKuo]

Yes, they just always do that, don't they?

Actually, they don't. There have been many nuclear space missions, and Cassini was the only one with a significant protest. And here's the kicker--the protest had no effect. Cassini was launched anyway. The oh so incredibly powerful anti-nuke lobby has stopped a grand total of zero nuclear space missions.

Face it, the anti-nuke crowd is nothing but a weak scapegoat here in the USA and more or less a non-entity in the Soviet Union/Russia. Ask yourself why the Soviets didn't use Orion. It certainly wasn't fear of anti-nuke protesters. No, it's a matter of ridiculous cost, technological challenge, technology risk, and so on.

Would we still require a pusher plate for a non manned mission?

Unless the "mission" is to blow up a spacecraft with a nuclear bomb, yes.

Do you have a link with more information on this?
Would this not limit us to flyby missions only?

Here's one link. Geoffrey Landis was kind enough to e-mail me a copy of the paper, but generally it's only available behind a paywall.

Braking at the target system is typically conceived of as done using Zubrin's interstellar medium brake, although I prefer faster (and more expensive) methods.

Currently, I'm developing a new concept I call "twin stream propulsion", which may be an improvement over my long time favored method of braking/return--relativistic kinetic impact powered rocket. Essentially, relativistic kinetic impacts can cause explosions with greater velocities greater than that of nuclear explosions (or even anti-matter). Using such relativistic explosions, it's possible to get around the limitations of nuclear propulsion.

[Siguy]

I agree about the protests around Cassini- they were extremely minor and mostly overblown. If NASA wanted to launch a full blown nuclear reactor they could, just as well.

As for Orion, well, if there was a large enough base of support from the public for it to actually be possible, I doubt protesters would actually stand much of a chance.

But yes, it is an extremely infeasible propulsion method for any spacecraft in the near future. The designs would not scale down well to research size; they were really meant for colonization. For space probes we have ion and other plasma or nuclear based engines that are much much safer and possibly quite a bit more efficient (though of course, with lower thrust).

[Ara Pacis]

In addition, the biggest benefit from an Orion NPP system is use in launching from the Earth's surface due to the presence of a local working fluid. In space, it's less effective. But if we were to use it on earth, the public pressure might actually be effective.

[Parallax M86]

Actually, they don't. There have been many nuclear space missions, and Cassini was the only one with a significant protest. And here's the kicker--the protest had no effect. Cassini was launched anyway. The oh so incredibly powerful anti-nuke lobby has stopped a grand total of zero nuclear space missions.

Face it, the anti-nuke crowd is nothing but a weak scapegoat here in the USA and more or less a non-entity in the Soviet Union/Russia. Ask yourself why the Soviets didn't use Orion. It certainly wasn't fear of anti-nuke protesters. No, it's a matter of ridiculous cost, technological challenge, technology risk, and so on.

Unless the "mission" is to blow up a spacecraft with a nuclear bomb, yes.

Here's one link. Geoffrey Landis was kind enough to e-mail me a copy of the paper, but generally it's only available behind a paywall.

Braking at the target system is typically conceived of as done using Zubrin's interstellar medium brake, although I prefer faster (and more expensive) methods.

Currently, I'm developing a new concept I call "twin stream propulsion", which may be an improvement over my long time favored method of braking/return--relativistic kinetic impact powered rocket. Essentially, relativistic kinetic impacts can cause explosions with greater velocities greater than that of nuclear explosions (or even anti-matter). Using such relativistic explosions, it's possible to get around the limitations of nuclear propulsion.

^Ditto. This sums up my thoughts on the matter.

This technology is realistically at minimum 35-40 years in the future. That's with good/adequate funding. If the political atmosphere about spaceflight stays the say probably over 50 years in the future.

[scottlowther]

FYI: I ran five long articles in Aerospace Projects Review on the Orion program. A relatively vast amount of technical data was presented on a number of the General Atomics designs, including the 4,000 ton USAF version.
APR: http://www.up-ship.com/eAPR/index.htm

[Siguy]

In addition, the biggest benefit from an Orion NPP system is use in launching from the Earth's surface due to the presence of a local working fluid. In space, it's less effective. But if we were to use it on earth, the public pressure might actually be effective.

Which of course, will never, EVER be utilized... For a good reason.

[Ara Pacis]

Which of course, will never, EVER be utilized... For a good reason.

That reason being public sentiment. I've heard that some designs are clean enough for government work.

[JustAFriend]

Would we still require a pusher plate for a non manned mission?

Dyson came up with designs with much smaller pusher plates for unmanned and fast (high-G acceleration versions).

If you read the book- well worth reading IMHO - they talk about using nuclear shaped charges and plastic in the bomb casings to provide more umph with less vehicle mass and higher accelerations.

[Siguy]

That reason being public sentiment. I've heard that some designs are clean enough for government work.

Don't kid yourself. Nuclear fallout is nasty, no matter how efficient the warhead is. The nuclear tests done in the 60s had lasting effects on the atmosphere. This would require even more and more regular detonations. Preserving the environment and public health is just as important as space exploration, since Earth is somewhere that a lot of people happen to live.

[Ara Pacis]

Don't kid yourself. Nuclear fallout is nasty, no matter how efficient the warhead is. The nuclear tests done in the 60s had lasting effects on the atmosphere. This would require even more and more regular detonations. Preserving the environment and public health is just as important as space exploration, since Earth is somewhere that a lot of people happen to live.

My point is: it still happened.

[Damburger]

NPP doesn't exist as a current, working technology because people don't like nuclear explosions happening in the atmosphere.

Pusher plate design was not a major engineering issue; the fact that steel won't ablate much if its a little way from a nuclear explosion was fairly well established through testing at the time of project Orion.

[Ara Pacis]

NPP doesn't exist as a current, working technology because people don't like nuclear explosions happening in the atmosphere.

Pusher plate design was not a major engineering issue; the fact that steel won't ablate much if its a little way from a nuclear explosion was fairly well established through testing at the time of project Orion.

They tested it with some steel spheres 100m or so away from a thermonuke, IIRC.

[Siguy]

My point is: it still happened.

But it's not happening again, unless we have WWIII (which unfortunately quite possible)

[Murphy]

The whole launching Orion from Earth thing is totally insane Cold-War thinking, it will never happen now. I mean the shear amount of Nuclear Weapons needed to be detonated in the atmosphere for even a single launch is huge, a whole program of hundreds of such launches would pretty quickly release more fallout than the entire atomic testing during the Cold-War.

And that's just the health and environmental aspects of it, think of the political and military consequences. The Orion vessel is essentially a mobile WMD platform fully capable of going anywhere at extreme speed and launching hundreds of nuclear weapons anywhere it wants. And not only that, but it is essentially immune to nuclear counter-attack, since if any nuke is sent against it, the ship can just turn so it's pusher plate absorbs the blast. It would totally upset the global strategic balance at a time when there is no need to do so. Not to mention the fact that any country trying to develop it would have to first tear up all its international commitments to the various test ban treaties and arms reduction protocols.

Its complete madness and will never be done. And for good reason.

[Siguy]

Agreed. And even construction in space faces some of the same issues, as well as the added problem of it just not being very efficient in comparison to other types of low impulse propulsion.

Now, nuclear shaped charges could still be used for some more malicious purposes (i.e. directed energy weapons) which would probably be quite useful in the far future if war in space actually does break out.

[caveman1917]

Yes, they just always do that, don't they?

Actually, they don't. There have been many nuclear space missions, and Cassini was the only one with a significant protest. And here's the kicker--the protest had no effect. Cassini was launched anyway. The oh so incredibly powerful anti-nuke lobby has stopped a grand total of zero nuclear space missions.

Face it, the anti-nuke crowd is nothing but a weak scapegoat here in the USA and more or less a non-entity in the Soviet Union/Russia. Ask yourself why the Soviets didn't use Orion. It certainly wasn't fear of anti-nuke protesters. No, it's a matter of ridiculous cost, technological challenge, technology risk, and so on.

Yes but i was referring more in general, like the nuclear phase-out legislation in several European countries which they managed to get on the table. I live in Belgium and my comment was because of that happening here only recently. I didn't specify indeed, and it's quite irrelevant to the discussion here anyway.

Unless the "mission" is to blow up a spacecraft with a nuclear bomb, yes.

Obviously, but it would make the design a lot more simple if there was no need to dampen the g's to human level.

Currently, I'm developing a new concept I call "twin stream propulsion", which may be an improvement over my long time favored method of braking/return--relativistic kinetic impact powered rocket. Essentially, relativistic kinetic impacts can cause explosions with greater velocities greater than that of nuclear explosions (or even anti-matter). Using such relativistic explosions, it's possible to get around the limitations of nuclear propulsion.

Care to elaborate, or provide a link?
I'm really interested in this matter.

[Ara Pacis]

The whole launching Orion from Earth thing is totally insane Cold-War thinking, it will never happen now. I mean the shear amount of Nuclear Weapons needed to be detonated in the atmosphere for even a single launch is huge, a whole program of hundreds of such launches would pretty quickly release more fallout than the entire atomic testing during the Cold-War.

And that's just the health and environmental aspects of it, think of the political and military consequences. The Orion vessel is essentially a mobile WMD platform fully capable of going anywhere at extreme speed and launching hundreds of nuclear weapons anywhere it wants. And not only that, but it is essentially immune to nuclear counter-attack, since if any nuke is sent against it, the ship can just turn so it's pusher plate absorbs the blast. It would totally upset the global strategic balance at a time when there is no need to do so. Not to mention the fact that any country trying to develop it would have to first tear up all its international commitments to the various test ban treaties and arms reduction protocols.

Its complete madness and will never be done. And for good reason.

Assuming the current political climate remains the same in the future.

And I wasn't referring to 100s of launches. Just a few might be sufficient to jump start a space infrastructure that can thereafter use non-NPP techniques.

[scottlowther]

a whole program of hundreds of such launches would pretty quickly release more fallout than the entire atomic testing during the Cold-War.

So you're saying it would be worth it, then. The entire Cold War atomic testing program released what is truly a trivial amount of fallout. And of course, Orion would not release anywhere near that amount, as the majority of the blasts would occur far above the surface, thus not causing any meaningful activation

The Orion vessel is essentially a mobile WMD platform fully capable of going anywhere at extreme speed and launching hundreds of nuclear weapons anywhere it wants.

This applies to *any* high-thrust, high Isp propulsion system you'd care to imagine.

if any nuke is sent against it, the ship can just turn so it's pusher plate absorbs the blast.

Utter hogwash. An Orion shock absorber system is a carefully tuned device; if you set off a nuke at the wrong time, wrong place or wrong yield, you'd smash the shock absorbers like so many fluorescent lights.

[Ara Pacis]

So you're saying it would be worth it, then. The entire Cold War atomic testing program released what is truly a trivial amount of fallout. And of course, Orion would not release anywhere near that amount, as the majority of the blasts would occur far above the surface, thus not causing any meaningful activation

I agree. High altitude bursts generate little fallout and the fallout that is produced is finer grained and remains at altitude for a longer period of time decaying to a low level before it drifts down toward the surface, in a large dispersion that means no one place will get very much.

This applies to *any* high-thrust, high Isp propulsion system you'd care to imagine.

Like launching lasers, electromagnetic catapults, or chemical rockets that some imaginary person my put nukes on.

Utter hogwash. An Orion shock absorber system is a carefully tuned device; if you set off a nuke at the wrong time, wrong place or wrong yield, you'd smash the shock absorbers like so many fluorescent lights.

It might be more damaging to just send a bunch of kinetic impactors or nukes from different directions.

[IsaacKuo]

So you're saying it would be worth it, then. The entire Cold War atomic testing program released what is truly a trivial amount of fallout. And of course, Orion would not release anywhere near that amount, as the majority of the blasts would occur far above the surface, thus not causing any meaningful activation

This is nonsense.

Before you even launch a single Orion rocket, the rocket system needs to be tested. How do you test a rocket thruster? On the ground. You've got this pusher plate which has a system of parallel struts which need to compress and extend in unison and keep everything at just the right alignment, as well as some sort of oil spraying system to spray oil onto the pusher plate between each launch, as well as the system to launch each nuke and detonate them at just the right time...

The system absolutely needs to be ground tested before attempting to launch a payload. While not a perfect simulation of the operating conditions, the closest you're going to get for a practical test setup is to point the system upside-down so it detonates the nukes not far above the ground.

And remember folks, nuclear bombs are expensive. Each bomb needs a fission primary, and this primary needs weapons grade fissionables.

Do you want to save money and time by skipping extensive ground testing and development? Then your nuclear rocket is operating on wishful thinking...up until the point where it blows up on or near the launchpad.

Otherwise, you're looking at expending thousands of nukes in dozens of ground tests. Not all of the tests will be successful, and the pusher plate system will need to be redesigned and refined until a practical thruster system is developed.

The ground testing alone will generate an amount of fallout on par with a nuclear war.

And did I mention it will be ridiculously expensive?

[Garrison]

This is nonsense.

Before you even launch a single Orion rocket, the rocket system needs to be tested. How do you test a rocket thruster? On the ground. You've got this pusher plate which has a system of parallel struts which need to compress and extend in unison and keep everything at just the right alignment, as well as some sort of oil spraying system to spray oil onto the pusher plate between each launch, as well as the system to launch each nuke and detonate them at just the right time...

The system absolutely needs to be ground tested before attempting to launch a payload. While not a perfect simulation of the operating conditions, the closest you're going to get for a practical test setup is to point the system upside-down so it detonates the nukes not far above the ground.

And remember folks, nuclear bombs are expensive. Each bomb needs a fission primary, and this primary needs weapons grade fissionables.

Do you want to save money and time by skipping extensive ground testing and development? Then your nuclear rocket is operating on wishful thinking...up until the point where it blows up on or near the launchpad.

Otherwise, you're looking at expending thousands of nukes in dozens of ground tests. Not all of the tests will be successful, and the pusher plate system will need to be redesigned and refined until a practical thruster system is developed.

The ground testing alone will generate an amount of fallout on par with a nuclear war.

And did I mention it will be ridiculously expensive?

Sorry but that's nonsense, why would they have to test thousands of warheads? You can develop the mechanical systems without using nukes, you test scale pusher designs with conventional explosives. There are tens of thousands of warheads already lying around, and I'm not talking about the ones currently in operation, where do you think the material from the ones that have been dismantled under the arms reduction treaties has gone?
And turning the assembly upside downside and firing into the air is the best testing method you can come up with? Forgive me but I just don't think you're really trying.
I suspect that if you applied the same ingenuity to Orion that you have to your own propulsion suggestions then you could answer any of the valid issues surrounding Orion.

[Ara Pacis]

I agree, test with analogs. Test an oil and plate mockup with a real nuke in space if need be. It's not like we haven't used nukes without testing them before.

[Elukka]

Without going into the economics, (I don't claim to possess any knowledge on how expensive mass production of small nuclear explosives would be) or the politics I don't see how the fallout would necessarily be a massive problem.

A global nuclear war tends to involve thousands of megatons of nukes going off. The Ivy Mike test was a dozen megatons. An Orion launching 5000-6000 metric tons of payload to LEO will expend about 0,3 megatons. Ways to minimize the fallout have been proposed, but I don't think a detailed study was ever done as the project was killed (and buried deep under a bunch of treaties) before that sort of thing was considered.

Final ground tests with actual nukes can be done underground, no?

[Ara Pacis]

A global nuclear war tends to involve thousands of megatons of nukes going off. The Ivy Mike test was a dozen megatons. An Orion launching 5000-6000 metric tons of payload to LEO will expend about 0,3 megatons.

Not to mention the placement of those explosions in a nuclear war scenario. War planners who target harder surface targets (e.g. a counterforce strike) tend to explode their nukes near the surface and with multiple weapons. Wanna whack a trainyard? Use a couple 100-300kt nukes at low enough altitude (i.e. a surface burst) to excavate a hole in the ground, hence more fallout.

[IsaacKuo]

Sorry but that's nonsense, why would they have to test thousands of warheads? You can develop the mechanical systems without using nukes, you test scale pusher designs with conventional explosives.

You can start with small scale models for a proof of concept, but that's all.

For tests of the actual thruster, you can't get around the fact that nuclear bombs are much more powerful than conventional bombs.

And you can't just test with a small number of nukes in outer space or underground. We're talking about a dynamic reciprocating machine where all of the parts need to be synchronized together. The parallel struts need to work in unison. The pulse unit launching system and the oil spraying system need to be coordinated with the movement of the struts. It needs to be operated in a full cyclic mode.

There are tens of thousands of warheads already lying around, and I'm not talking about the ones currently in operation, where do you think the material from the ones that have been dismantled under the arms reduction treaties has gone?

Tens of thousands? Where? According to this article, the US has about 5,200 warheads deployed or in reserve, and about 4,200 awaiting disassembly.

In any case it's a limited resource to mine for weapons grade fissionables.

And turning the assembly upside downside and firing into the air is the best testing method you can come up with? Forgive me but I just don't think you're really trying.
I suspect that if you applied the same ingenuity to Orion that you have to your own propulsion suggestions then you could answer any of the valid issues surrounding Orion.

If you've got a better idea for how to flight rate the thruster, please suggest it.

I have no illusions about the sort of extensive interplanetary industrialization of space would be required before my interstellar propulsion concepts could be flight rated. I find these concepts interesting in that they suggest what may be possible in the future, but I don't expect to see any of them in my lifetime (unless medical technology improvements in the next decades greatly improve the duration of my lifetime).

I've spent a lot of time thinking about how to accomplish CATS also, but I haven't come up with anything good yet. Even if some of my ideas might work, I can't think of any way to develop them in an inexpensive way. Most of them aren't suitable for ground testing, and if something needs to be tested in space, then you pretty much already need CATS to develop it inexpensively (contrast our development of solar sails with electrostatic ion thrusters). If a CATS scheme is too expensive to develop, then it's not really CATS.