It's actually the nuclear test ban treaty, not the OST treaty that prohibits Orion - but neither prohibits nuclear pulse in its more general form.
The test ban treaty prohibits use of nuclear weapons to get into orbit. The Outer Space Treaty - not so obvious - prohibits weapons of mass destruction in space - but are hydrogen bombs used purely as a method of propulsion still counted as weapons of mass destruction in this sense?
I am not a lawyer and this is not legal advice
The OST treaty prohibits all weapons of mass destruction in space (not specifically nuclear) - so if you were able to get the Orion into orbit - then you would need to show that it is not a weapon of mass destruction.
Since it's designed to use nuclear weapons as a method of propulsion, rather than as a weapon, I'm not sure what the answer would be there. Would depend on whether other countries object I suppose - though can imagine that other countries might reasonably be a bit nervous to see that e.g. US, or Russia or China has an interplanetary spacecraft that works by exploding thousands of hydrogen bombs behind it wherever it goes.
So maybe it would be classified as a weapon of mass destruction. But - seems a tricky thing to decide - and I'm not a lawyer, would need to consult a space lawyer on this and they might well have differing opinions it also I imagine.
But - that's beside the point unless you build the Orion in orbit.
If you build it on the ground and use exploding nuclear weapons to get it into space, then it violates the test ban treaty. That prohibits nuclear weapons that release radiation into the atmosphere - doesn't matter about intention - even if being used to excavate a canal (as in early suggestions for ways to use nuclear weapons) - would be prohibited by the test ban treaty.
Limited Test Ban Treaty (permits underground tests)
That was signed and also ratified by the US. This means the US definitely can't do an Orion launch. It's not signed or ratified by China.
Both China and US signed the Comprehensive Nuclear-Test-Ban Treaty but neither have ratified it so far.
(see Ratification - need for a country to approve the action of those who signed the treaty)
That would seem to leave a possible small loophole for China to build and launch an Orion spacecraft - but - I don't know if it does - would need to consult a lawyer about that.
There are problems anyway from moral point of view, that it might cause 10 extra deaths from cancer per launch. True that other things with similar budgets also lead to extra deaths in various ways, still, is a hard thing to sell and is the reason Freeman Dyson gave up on it.
However, if it was urgently needed for some civilization threatening disaster surely we'd set those issues aside at least temporarily - could have a temporary suspension of the test ban treaty just for launch of the Orion.
If all signatories agreed not to object to the launch say, just for the launch or launches needed to deal with the hazard, not sure you need to do more than that.
So, suppose that we desperately needed to send a few thousand tons into space quickly - for instance to divert a massive incoming comet from the Oort cloud - most likely with a few months of notice in that case. Or some near Earth asteroid - in that case - we already have reasonable confidence that there are no really large asteroids likely to hit Earth in near future, but may happen further into the future.
This is a very unlikely scenario in the near future - more likely to get far smaller impacts first. But some time in the next few ten million years, Earth is likely to be target of a really large asteroid. In that case, if we still have a technological civilization on Earth, and haven't invented any better way to do it, the Orion might be useful.
In near future, likely to be smaller asteroids, and likely to be asteroids orbiting close to the Earth so years of notice most likely - unless really tiny. There are various techniques for diverting them with enough time like that, so won't need the Orion.
Can't see it being approved for general use. So I'd be astonished if it was needed in this way in my lifetime or even for, say ten thousand years into future, highly unlikely that this is needed
The nuclear pulse - more general idea - though - that's more promising, and could be cleaner. Also if built in space - then - you don't have advantage of launch from Earth of thousands of tons - but still very fast interplaneteray spacecraft and no significant radiation issues.
However the technology doesn't exist yet, so more work to be done.
The hydrogen bombs based Orion fusion weapons spaceship could be built quite quickly - especially if we had some really major reason for building it - we have all the technology - it's just the radiation hazards and the test ban treaty that prevent it.
Plus I think other nations not the launching state could be justifiably nervous about the exploding hydrogen bombs - and the launching state also - about what if it goes wrong in some way e.g. drops too many hydrogen bombs on the launching nation, or crashes soon after lift off - can that be made safe, really? - and the extra radiation deaths are an issue also, radiation clouds from the air bursts (even though modern bombs are cleaner than they used to be).
Also all the Electro Magnetic Pulses from all those explosions destroying electronic transmission line equipment and such like during every launch springs to mind as another issue.
But in the very remote chance that we spot an incoming giant asteroid or comet and this is the only way to divert it, it remains a useful idea to have at hand to call on if we really need it.
Work in progress, several studies and projects
Nuclear pulse propulsion
Project Orion (nuclear propulsion)
The test ban treaty prohibits use of nuclear weapons to get into orbit. The Outer Space Treaty - not so obvious - prohibits weapons of mass destruction in space - but are hydrogen bombs used purely as a method of propulsion still counted as weapons of mass destruction in this sense?
LEGAL DISCLAIMER
I am not a lawyer and this is not legal advice
DETAILS
The OST treaty prohibits all weapons of mass destruction in space (not specifically nuclear) - so if you were able to get the Orion into orbit - then you would need to show that it is not a weapon of mass destruction.
Since it's designed to use nuclear weapons as a method of propulsion, rather than as a weapon, I'm not sure what the answer would be there. Would depend on whether other countries object I suppose - though can imagine that other countries might reasonably be a bit nervous to see that e.g. US, or Russia or China has an interplanetary spacecraft that works by exploding thousands of hydrogen bombs behind it wherever it goes.
So maybe it would be classified as a weapon of mass destruction. But - seems a tricky thing to decide - and I'm not a lawyer, would need to consult a space lawyer on this and they might well have differing opinions it also I imagine.
But - that's beside the point unless you build the Orion in orbit.
If you build it on the ground and use exploding nuclear weapons to get it into space, then it violates the test ban treaty. That prohibits nuclear weapons that release radiation into the atmosphere - doesn't matter about intention - even if being used to excavate a canal (as in early suggestions for ways to use nuclear weapons) - would be prohibited by the test ban treaty.
Limited Test Ban Treaty (permits underground tests)
That was signed and also ratified by the US. This means the US definitely can't do an Orion launch. It's not signed or ratified by China.
Both China and US signed the Comprehensive Nuclear-Test-Ban Treaty but neither have ratified it so far.
(see Ratification - need for a country to approve the action of those who signed the treaty)
That would seem to leave a possible small loophole for China to build and launch an Orion spacecraft - but - I don't know if it does - would need to consult a lawyer about that.
There are problems anyway from moral point of view, that it might cause 10 extra deaths from cancer per launch. True that other things with similar budgets also lead to extra deaths in various ways, still, is a hard thing to sell and is the reason Freeman Dyson gave up on it.
However, if it was urgently needed for some civilization threatening disaster surely we'd set those issues aside at least temporarily - could have a temporary suspension of the test ban treaty just for launch of the Orion.
If all signatories agreed not to object to the launch say, just for the launch or launches needed to deal with the hazard, not sure you need to do more than that.
SITUATION THAT MIGHT NEED THE ORION URGENTLY
So, suppose that we desperately needed to send a few thousand tons into space quickly - for instance to divert a massive incoming comet from the Oort cloud - most likely with a few months of notice in that case. Or some near Earth asteroid - in that case - we already have reasonable confidence that there are no really large asteroids likely to hit Earth in near future, but may happen further into the future.
This is a very unlikely scenario in the near future - more likely to get far smaller impacts first. But some time in the next few ten million years, Earth is likely to be target of a really large asteroid. In that case, if we still have a technological civilization on Earth, and haven't invented any better way to do it, the Orion might be useful.
In near future, likely to be smaller asteroids, and likely to be asteroids orbiting close to the Earth so years of notice most likely - unless really tiny. There are various techniques for diverting them with enough time like that, so won't need the Orion.
Can't see it being approved for general use. So I'd be astonished if it was needed in this way in my lifetime or even for, say ten thousand years into future, highly unlikely that this is needed
NUCLEAR PULSE
The nuclear pulse - more general idea - though - that's more promising, and could be cleaner. Also if built in space - then - you don't have advantage of launch from Earth of thousands of tons - but still very fast interplaneteray spacecraft and no significant radiation issues.
However the technology doesn't exist yet, so more work to be done.
The hydrogen bombs based Orion fusion weapons spaceship could be built quite quickly - especially if we had some really major reason for building it - we have all the technology - it's just the radiation hazards and the test ban treaty that prevent it.
Plus I think other nations not the launching state could be justifiably nervous about the exploding hydrogen bombs - and the launching state also - about what if it goes wrong in some way e.g. drops too many hydrogen bombs on the launching nation, or crashes soon after lift off - can that be made safe, really? - and the extra radiation deaths are an issue also, radiation clouds from the air bursts (even though modern bombs are cleaner than they used to be).
Also all the Electro Magnetic Pulses from all those explosions destroying electronic transmission line equipment and such like during every launch springs to mind as another issue.
But in the very remote chance that we spot an incoming giant asteroid or comet and this is the only way to divert it, it remains a useful idea to have at hand to call on if we really need it.
Work in progress, several studies and projects
Nuclear pulse propulsion
Project Orion (nuclear propulsion)
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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