Project Orion
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John Clark
Sep 20, 2025, 2:56:02 PM (8 days ago) Sep 20
to extro...@googlegroups.com, 'Brent Meeker' via Everything List
Just a few hours ago very a interesting documentary about project Orion was posted on YouTube:
I've been fascinated by this idea for years, back in 1998 I posted the following to the old Extropian list, the video contains some details that I didn't know then because they were still classified top-secret in 1998:
===
I've been reading a little about an incredible idea taken very seriously in the late 50's and early 60's but today is almost completely forgotten, it was called Project Orion. The idea was to make a spaceship big enough for 150 people and all the equipment they could ever want and blast it into space. They wanted to make it 135 feet in diameter and 160 feet high and they wanted most of that space to be usable by people not wasted on fuel. They figured weight would be no problem, if a crew member wanted to bring along his antique bowling ball collection and his own personal barber chair there would be no objection. The advocates of this approach were not interested in low Earth orbit or even the moon, they were certain they could be on Mars by 1965 and Saturn by 1970, the leader of the project was determined to visit Pluto. And they figured all this would cost less than 10% what the Apollo moon project did.
You might think that these people must have been a bunch of crackpots, but it's not so. Nobel Prize winners Niels Bohr, Hans Bethe and Harold Urey were all enthusiastic advocates of the idea. Freeman Dyson thought the idea was so brilliant that he took a one year leave of absence from the prestigious
Institute of Advanced Study so he could work full time on the project.
Yes, there is a catch, Project Orion needed nuclear energy, even worse it needed nuclear bombs. The Orion spacecraft would contain 2000 nuclear bombs, most in the 20 kiloton range, the size of the bomb that destroyed Nagasaki. A bomb in a tank of water would shoot out the back of the ship, when it was 100 feet away it would explode, the water would hit a carefully designed 75 ton pusher plate and accelerate the ship. Between the pusher plate and the ship were 50 foot long gas filled shock absorbers to even out the jerk. They wanted everything to be as cheap as possible, so they asked the Coca-Cola company for the blueprints of one of their vending machines, then they scaled it up a little and planned to use it as the mechanism to dispense the bombs.
The pusher plate was obviously the most important part of the design. If you explode a powerful bomb near a circular plate of constant thickness it will shatter because of the uneven stresses that build up, but it turns out that if you carefully taper the plate and make certain that the explosion is dead
center, the plate will be extraordinarily resistant to damage. A layer on the plate will be vaporized by the heat but if some heavy protective oil is sprayed on it before each use it would be good for 2000 blasts. This beast was tough, if it was properly oriented the Orion Spacecraft could survive a 16 megaton H bomb blast from only two thousand feet away, a fact of more than passing interest to the military. Orion needed lots of radiation shielding to protect the crew, but weight was never an issue so this was no problem.
Wernher von Braun thought all this was a dumb idea, then he saw a movie of the launch of a one meter working model of Orion that shot 6 carefully timed high explosives chemical bombs out the back of the model, it rose 300 feet into the air in stable controlled flight. Wernher von Braun became a vocal
supporter of project Orion.
They planned to launch Orion from atop eight 250 foot towers in Jackass Flats Nevada. The first bomb would be tiny, just .1 kiloton (100 tons of TNT) exploded 100 feet below the craft and 150 feet above the ground, then a new and slightly larger bomb would be spit out the back every second for 50 seconds, the last bomb would be the largest, 20 kilotons, and by then the craft would be out of the atmosphere, the total yield of the 50 bombs would be 200 kilotons. The launch would have been a spectacular sight, it'd make the Space Shuttle look like a bottle rocket.
Project Orion was led by Ted Taylor, a mediocre physicist but a good inventor. Taylor had one unique talent, he has been called by some the best nuclear weapon engineer on planet Earth and the Leonardo da Vinci of nuclear bomb design. Taylor is the man who figured out how a two foot long 200 pound bomb could be made as powerful as the 12 foot long 10 ton World War 2 Nagasaki bomb. The reason the Orion spaceship was so much bigger and faster than anything we have today is that pound for pound such bombs have about a million times as much energy as any chemical rocket fuel.
Orion wasn't the only thing Taylor was interested in, he found a way to make a new type of nuclear bomb, one that would produce a highly directional blast. He designed a little one kiloton bomb that could blast a 1000 foot tunnel straight through solid rock, he wanted to build a cheap tunnel between New York and San Francisco and have a supersonic subway 3000 miles long.
Considering the big controversy we had last year when a deep space probe was launched with just a few pounds of non weapon grade Plutonium on it to power the electronics it may seem incredible and irresponsible that anyone would even consider something as environmentally unfriendly as Orion, but we live in a very different world. At the time Orion was under serious study the USA was blowing up one megaton bombs deep under the sea and 300 miles in space and the USSR was blowing up 57 megaton bombs in the atmosphere, Orion seemed and indeed was pretty benign compared to that.
It all came to nothing of course, in 1963 the test ban treaty was signed stopping all nuclear explosions in space or the atmosphere making Orion illegal. The project died, but to this day most say it would have worked technologically if not politically.
Idea for a science fiction novel: A huge nickel iron asteroid is heading for Earth, it would take a 8 gigaton bomb to divert it but no existing rocket is nearly powerful enough to deliver such a huge payload to the asteroid. The Earth seems doomed, then our hero remembers Project Orion.
You might think that these people must have been a bunch of crackpots, but it's not so. Nobel Prize winners Niels Bohr, Hans Bethe and Harold Urey were all enthusiastic advocates of the idea. Freeman Dyson thought the idea was so brilliant that he took a one year leave of absence from the prestigious
Institute of Advanced Study so he could work full time on the project.
Yes, there is a catch, Project Orion needed nuclear energy, even worse it needed nuclear bombs. The Orion spacecraft would contain 2000 nuclear bombs, most in the 20 kiloton range, the size of the bomb that destroyed Nagasaki. A bomb in a tank of water would shoot out the back of the ship, when it was 100 feet away it would explode, the water would hit a carefully designed 75 ton pusher plate and accelerate the ship. Between the pusher plate and the ship were 50 foot long gas filled shock absorbers to even out the jerk. They wanted everything to be as cheap as possible, so they asked the Coca-Cola company for the blueprints of one of their vending machines, then they scaled it up a little and planned to use it as the mechanism to dispense the bombs.
The pusher plate was obviously the most important part of the design. If you explode a powerful bomb near a circular plate of constant thickness it will shatter because of the uneven stresses that build up, but it turns out that if you carefully taper the plate and make certain that the explosion is dead
center, the plate will be extraordinarily resistant to damage. A layer on the plate will be vaporized by the heat but if some heavy protective oil is sprayed on it before each use it would be good for 2000 blasts. This beast was tough, if it was properly oriented the Orion Spacecraft could survive a 16 megaton H bomb blast from only two thousand feet away, a fact of more than passing interest to the military. Orion needed lots of radiation shielding to protect the crew, but weight was never an issue so this was no problem.
Wernher von Braun thought all this was a dumb idea, then he saw a movie of the launch of a one meter working model of Orion that shot 6 carefully timed high explosives chemical bombs out the back of the model, it rose 300 feet into the air in stable controlled flight. Wernher von Braun became a vocal
supporter of project Orion.
They planned to launch Orion from atop eight 250 foot towers in Jackass Flats Nevada. The first bomb would be tiny, just .1 kiloton (100 tons of TNT) exploded 100 feet below the craft and 150 feet above the ground, then a new and slightly larger bomb would be spit out the back every second for 50 seconds, the last bomb would be the largest, 20 kilotons, and by then the craft would be out of the atmosphere, the total yield of the 50 bombs would be 200 kilotons. The launch would have been a spectacular sight, it'd make the Space Shuttle look like a bottle rocket.
Project Orion was led by Ted Taylor, a mediocre physicist but a good inventor. Taylor had one unique talent, he has been called by some the best nuclear weapon engineer on planet Earth and the Leonardo da Vinci of nuclear bomb design. Taylor is the man who figured out how a two foot long 200 pound bomb could be made as powerful as the 12 foot long 10 ton World War 2 Nagasaki bomb. The reason the Orion spaceship was so much bigger and faster than anything we have today is that pound for pound such bombs have about a million times as much energy as any chemical rocket fuel.
Orion wasn't the only thing Taylor was interested in, he found a way to make a new type of nuclear bomb, one that would produce a highly directional blast. He designed a little one kiloton bomb that could blast a 1000 foot tunnel straight through solid rock, he wanted to build a cheap tunnel between New York and San Francisco and have a supersonic subway 3000 miles long.
Considering the big controversy we had last year when a deep space probe was launched with just a few pounds of non weapon grade Plutonium on it to power the electronics it may seem incredible and irresponsible that anyone would even consider something as environmentally unfriendly as Orion, but we live in a very different world. At the time Orion was under serious study the USA was blowing up one megaton bombs deep under the sea and 300 miles in space and the USSR was blowing up 57 megaton bombs in the atmosphere, Orion seemed and indeed was pretty benign compared to that.
It all came to nothing of course, in 1963 the test ban treaty was signed stopping all nuclear explosions in space or the atmosphere making Orion illegal. The project died, but to this day most say it would have worked technologically if not politically.
Idea for a science fiction novel: A huge nickel iron asteroid is heading for Earth, it would take a 8 gigaton bomb to divert it but no existing rocket is nearly powerful enough to deliver such a huge payload to the asteroid. The Earth seems doomed, then our hero remembers Project Orion.
Lawrence Crowell
Sep 20, 2025, 4:37:42 PM (8 days ago) Sep 20
to extropolis
In my book "Can Star Systems Be Explored?" I do mention this. It used mini-atomic bombs to propel it.
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Lawrence Crowell
Sep 20, 2025, 4:39:55 PM (8 days ago) Sep 20
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John Clark
Sep 21, 2025, 6:42:29 AM (7 days ago) Sep 21
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On Sat, Sep 20, 2025 at 4:37 PM Lawrence Crowell <goldenfield...@gmail.com> wrote:
> In my book "Can Star Systems Be Explored?" I do mention this. It used mini-atomic bombs to propel it.
https://www.worldscientific.com/worldscibooks/10.1142/6423?srsltid=AfmBOopcMZw0mLaFaGOARhbya_ySiErrqi8HAAZJwTVm_Rb8V5rMicHE#t=aboutBook
==
The efficiency of a rocket depends on its exhaust velocity, the faster the better. The space shuttle's oxygen hydrogen engine had a exhaust velocity of about 4500 meters per second and that's very good for a chemical rocket, the nuclear heated rocket called NERVA tested in the 1960's had a exhaust velocity of 8000 meters per second, and ion engines are about 80,000. With the help of Americium you could do better, much better, say around 200,000,000 meters per second. And then you could get to Mars in 2 weeks instead of 2 years.
In the January 2001 issue of Nuclear Instruments and Methods, Yigal Ronen and Eugene Shwageraus calculate that a metallic 2-D film of Americium-242 less than a thousandth of a millimeter thick would undergo fission. This is so thin that rather than heat the bulk material the energy of the process would go almost entirely into the speed of the primary fission products, they would go free and provide thrust.
Engineering the rocket would be tricky and I'm not sure I'd want to be on the same planet as a large scale Americium 242 production facility, but it's an interesting idea.
You could make a bomb with Americium-242 (half life about a century) and it would be small enough to fit in your pocket because its critical mass is less than 1% that of Plutonium. But you could do other things with Americium-242, like make a super efficient rocket.
The primary products of a fission reaction are about that fast, but if you use Uranium235 or Plutonium 239 the large bulk of the material will absorb the primary fission products and just heat up the material, which slows fission products down. However the critical mass for Americium-242 is so small that wouldn't be a problem.
In the January 2001 issue of Nuclear Instruments and Methods, Yigal Ronen and Eugene Shwageraus calculate that a metallic 2-D film of Americium-242 less than a thousandth of a millimeter thick would undergo fission. This is so thin that rather than heat the bulk material the energy of the process would go almost entirely into the speed of the primary fission products, they would go free and provide thrust.
Engineering the rocket would be tricky and I'm not sure I'd want to be on the same planet as a large scale Americium 242 production facility, but it's an interesting idea.
John K Clark See what's on my new list at Extropolis
;;l
Lawrence Crowell
Sep 21, 2025, 9:03:28 AM (7 days ago) Sep 21
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This sort of reaction mass system has a high specific impulse, but a low thrust. High thrust rockets tend to have a large flux of material and very high specific impulse reaction-mass systems, ion propulsion etc, tend to have small flux of reaction mass at much higher velocity. The result is that these are good for space probes sent to outer planets and the like, but they take a lot of time to accelerate at low acceleration to high velocity.
The figure of 2x10^8m/sec or 200,000km/sec is suspect. Americium 242 does not fission spontaneously at a high rate. Further, nuclear processes tend to occur at energy ~ 1.0MeV per nucleon. The ratio of this to the mass of Am242 is then ~ 1/242 = .0041. This plus one 1.0041 gives the gamma factor γ = 1/√(1 - v^/c^2), and that the velocity is v = c√(1 - 1/γ^2) gives then .045c or 13,500km/sec. v = 2x10^8m/sec is .67c.
LC
John Clark
Sep 22, 2025, 7:30:16 AM (6 days ago) Sep 22
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On Sun, Sep 21, 2025 at 9:03 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:
> The figure of 2x10^8m/sec or 200,000km/sec is suspect. Americium 242 does not fission spontaneously at a high rate. Further, nuclear processes tend to occur at energy ~ 1.0MeV per nucleon. The ratio of this to the mass of Am242 is then ~ 1/242 = .0041. This plus one 1.0041 gives the gamma factor γ = 1/√(1 - v^/c^2), and that the velocity is v = c√(1 - 1/γ^2) gives then .045c or 13,500km/sec. v = 2x10^8m/sec is .67c.
But the nucleus has split so the fission products would not have a mass of 242 but would be about half of that. And one of the fission products would be free neutrons, and they would have a mass of just 1.
John K Clark
Lawrence Crowell
Sep 22, 2025, 10:34:55 AM (6 days ago) Sep 22
to extro...@googlegroups.com
On Mon, Sep 22, 2025 at 6:30 AM John Clark <johnk...@gmail.com> wrote:
On Sun, Sep 21, 2025 at 9:03 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:> The figure of 2x10^8m/sec or 200,000km/sec is suspect. Americium 242 does not fission spontaneously at a high rate. Further, nuclear processes tend to occur at energy ~ 1.0MeV per nucleon. The ratio of this to the mass of Am242 is then ~ 1/242 = .0041. This plus one 1.0041 gives the gamma factor γ = 1/√(1 - v^/c^2), and that the velocity is v = c√(1 - 1/γ^2) gives then .045c or 13,500km/sec. v = 2x10^8m/sec is .67c.But the nucleus has split so the fission products would not have a mass of 242 but would be about half of that. And one of the fission products would be free neutrons, and they would have a mass of just 1.John K Clark
The point is that the total energy of the fission is around 1MeV/nucleon, and if that energy is partitioned among the fission products the same result would more or less hold. If the fission products were of equal mass the result would be the same as mine above. Fission products Ba and Kr are common with 142 and 92 nucleons are possible. The results will nowhere be near the relativistic .67c. In fact nucleons in a nucleus only move at around .1c or so.
LC
In a post I made to the Extropian list in 2018 I talked about a Americium-242 rocket:==You could make a bomb with Americium-242 (half life about a century) and it would be small enough to fit in your pocket because its critical mass is less than 1% that of Plutonium. But you could do other things with Americium-242, like make a super efficient rocket.The efficiency of a rocket depends on its exhaust velocity, the faster the better. The space shuttle's oxygen hydrogen engine had a exhaust velocity of about 4500 meters per second and that's very good for a chemical rocket, the nuclear heated rocket called NERVA tested in the 1960's had a exhaust velocity of 8000 meters per second, and ion engines are about 80,000. With the help of Americium you could do better, much better, say around 200,000,000 meters per second. And then you could get to Mars in 2 weeks instead of 2 years.The primary products of a fission reaction are about that fast, but if you use Uranium235 or Plutonium 239 the large bulk of the material will absorb the primary fission products and just heat up the material, which slows fission products down. However the critical mass for Americium-242 is so small that wouldn't be a problem.
In the January 2001 issue of Nuclear Instruments and Methods, Yigal Ronen and Eugene Shwageraus calculate that a metallic 2-D film of Americium-242 less than a thousandth of a millimeter thick would undergo fission. This is so thin that rather than heat the bulk material the energy of the process would go almost entirely into the speed of the primary fission products, they would go free and provide thrust.
Engineering the rocket would be tricky and I'm not sure I'd want to be on the same planet as a large scale Americium 242 production facility, but it's an interesting idea.
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