In the years immediately following the end of the Second World War, several of the scientists who took part in the Manhattan Project had an explosive idea.
They wondered if we could harness the incredible power of atomic bombs and put them to use for peaceful purposes.
In particular, what if we could use atomic bombs to literally blast ships into space?
This idea went far further than you probably think it did.
Learn more about Project Orion and the quite serious idea of blasting ships into space on this episode of Everything Everywhere Daily.
There are different types of crazy ideas. There are plausible crazy ideas and implausible crazy ideas.
In a previous episode, I talked about a project which was conceived called Atlantropa, which proposed damming the entire Mediterranean Sea in two different places, as well as flooding much of Central Africa to create an inland system of waterways.
Atlantropa is what I would call an implausible crazy idea. Assuming it could be accomplished would require an enormous amount of the world’s productive capacity, and upon completion, it would have destroyed enormous ecosystems on both sea and land.
Atlantropa was nothing more than an idea hatched by someone who never really sat down and did the math to see how it would work.
The topic of this episode is not quite the same as the Atlantropa episode. Project Orion was, by all accounts, a crazy idea. However, unlike Atlantropa, some very smart people sat down and did the math and came to the conclusion that it could actually work.
Whether it would have been a good idea is a completely different story.
The story starts in the aftermath of World War II and the Manhattan Project, which created the world’s first atomic bomb.
Many of the scientists who had worked on the bomb were horrified at the destructive potential of the device they had created and were looking for peaceful uses for the device.
In particular, one physicist from Los Alamos and a key member of the Manhattan Project was Stanis?aw Ulam.
Stanis?aw Ulam was one of the giants of 20th-century physics and mathematics. Not only did he help create hydrogen bombs, but he also developed the ideas of cellular automation and Monte Carlo simulations in computing.
In 1946, Ulam realized that the enormous forces unleashed in an atomic blast could potentially be used to propel an object into space.
In a previous episode, I mentioned Operation Plumbob, which was a series of atomic tests that were conducted in Nevada in the late 1950s. One of these tests involved an underground detonation of a nuclear device. The device was placed down a deep borehole which was then covered by a steel cap that was welded in place.
The detonation sent the force of the blast straight up the borehole and blew off the cap at speeds six times greater than the escape velocity to leave Earth. Some people think that steel cover might have been the first thing humans ever launched into space…..assuming it survived the flight through the atmosphere.
That method of using an atomic bomb to launch something into space was not what Ulam was thinking.
He was thinking of dropping bombs behind a vehicle which would then be detonated to propel it into space. It wouldn’t just be one bomb either, but a series of bombs that would be ejected behind a ship to keep propelling it.
The idea was called nuclear pulse propulsion.
In the few seconds since I’ve mentioned this, there is a good chance you might have come up with several objections as to why this wouldn’t work or why it at least wouldn’t be a good idea. I assure you, those were addressed, and I will get to those in a bit.
In 1947, with the assistance of Frederick Reines, who later went on to win the Nobel Prize in Physics, Ulam did the calculations and found that the idea was plausible. He and Reines published his results in an internal memorandum.
The idea didn’t die. In 1955, Ulam wrote a more extensive classified paper on the subject detailing how such a system would work.
The idea floated around for years, and in 1958 it was picked up by the physicist Ted Taylor who worked for General Atomics, which was a subsidiary of the defense contractor General Dynamic.
Taylor convinced another major physicist, Freeman Dyson, who worked at the Institute for Advanced Study in Princeton, to come and work on the project for a year.
It was given the name Project Orion and DARPA, the Defense Advanced Research Projects Agency, agreed to fund it to the tune of $1 million dollars per year. The fact that the Soviet Union had just put Sputnik into orbit several months before didn’t hurt.
Taylor, Dyson, and the team on Project Orion had to think about how to turn this from a theoretical idea to something that could actually work.
One of the first realizations they had was that, at least from an energy and thrust standpoint, a nuclear explosion wasn’t any different than a chemical explosion. It was just bigger.
The first challenge was how do you develop such a vehicle.
Vehicles designed for spaceflight usually have to be small and lightweight to save on fuel. Such a small spacecraft would literally be ripped apart in a nuclear blast.
So, for starters, the vehicle would have to be large and well-built. Instead of lightweight metals like aluminum or titanium, it would have to build from heavier materials such as iron and steel. To this extent, it would have to be more like a battleship than an airplane.
The vehicle would have to have a very broad, flat surface that was known as a pusher plate. The pusher plate would be the surface that the blast from the explosion would push against to propel the vehicle.
However, it wasn’t as simple as just having a very broad surface to push against. Nuclear explosions are…..well…..nuclear explosions. There will be some amount of damage done to the pusher plate from the high temperatures, so it would have to be designed to degrade to a certain extent. Similar to how a heat shield is designed to degrade when a spaceship reenters the atmosphere.
Finally, the thrust provided by a bomb would be an enormous jolt to the vehicle and anyone inside it.
There would have to be some sort of shock absorber to even out the jolts that came from the explosions. They originally considered an airbag system but realized even the slightest flaw in the explosions could rupture the bag and destroy the vehicle.
They eventually settled on a dual system of springs and gas pistons.
The issue of the size of the shock from each bomb also had to be considered. The type of explosions used would need to be smaller bombs, not enormous megaton hydrogen bombs. These would be much smaller than the bombs used in Hiroshima or Nagasaki.
These would be smaller explosions under one kiloton.
The bombs would have to be ejected out the back of the vehicle through a hole in the pusher plate.
However, smaller explosions mean you need more of them in order to get an equivalent amount of thrust. It was calculated that the optimal place to detonate the bomb would be 20-30 meters beyond the pusher plate at a rate of one explosion every 1.1 seconds.
The total number of explosions required to launch some of the largest designs approached 800. 800 nuclear bombs, detonating one after the other, about one second apart.
To put that into perspective, there have only been 520 atmospheric nuclear explosions conducted in human history.
The total amount of thrust generated by this system would have been significantly greater than that generated from chemical rockets.
There were big plans floated by the Orion team for the type of missions that were possible. They felt that they could do a round trip mission to Mars that could be completed in four months.
The motto of the Project Orion team in the late 50s was “Mars by 1965. Saturn by 1970”. Mind you, this was before any human being had been put into orbit.
A proposed landing on Mars would require more explosions to slowdown and land the craft as well as to launch it off the surface of the planet again.
Many of the team members for Project Orion were so optimistic they were planning to take their families with them on trips.
All of this planning was theoretical. No one had ever propelled anything using pulse propulsion, aka explosions, before, even using conventional explosives.
So, in 1959, they set out to do just that. They conducted a test to see if they could, in fact, launch something using a series of rapid conventional explosives.
The model of the vehicle they built managed to reach an altitude of 100 meters or 300 feet. You can find videos of this test on YouTube that have been declassified.
The biggest problem with the test was stability. You can’t really steer an explosion. The model did go up, but it did so in a very awkward fashion. It was very easy to see how one blast that went the wrong way could easily tip it in the wrong direction and have it crash into the ground.
Despite the strong belief in the program by the Orion team, the idea never really caught on anywhere else. DARPA eventually pulled funding and Project Orion eventually sought funding from the military.
The Air Force envisioned Orion launching a massive platform that could sit in space filled with nuclear warheads that could be dropped anywhere on the planet at a moment’s notice.
They basically wanted to make a death star.
The Marines envisioned a system that could transport hundreds of troops around the world in 30 minutes.
There was a problem with all of these ideas, and it’s something I haven’t mentioned yet that you’ve probably thought of already.
Radiation and nuclear fallout.
The atmospheric nuclear tests which had already been conducted were starting show evidence all over the planet. High levels of strontium-90 we found in milk and were showing up in the teeth of babies. This led to increased public concern about atmospheric testing which eventually led to the Partial Nuclear Test Ban Treaty of 1963.
It banned the detonation of nuclear weapons in the atmosphere, in the sea, and in space.
Dyson’s initial calculations was that each Orion launch would kill up to ten people from radioactive fallout.
Moreover, Freeman Dyson also couldn’t get around the the problem of radiation. Anyone inside of an Orion vehicle would be extremely close to every detonation, which would mean being exposed to high amounts of powerful gamma radiation.
Given the proximity of the crew, they would receive a dose of 700 rads of radiation for every detonation. A 1000 rad dose is considered lethal. 700 rads would probably kill most people if not cause serious illness.
It would require an enormous amount of radiation shielding.
After the passage of the Test Ban Treaty, interest in Project Orion vanished, for obvious reasons.
Despite the lack of interest in Project Orion, interest in nuclear pulse propulsion never completely disappeared.
While it would probably never be used to launch anything from the surface of the planet, it could be used in space to deflect an asteroid heading towards Earth. In fact, it could probably provide the best short term solution if our planet should ever find itself on a collision course with a large object.
There are also ideas for nuclear pulse propulsion that doesn’t involve bombs. There are fusion based systems that have been proposed that would just expel a small pellet behind a spaceship that could be hit with lasers to ignite a fusion reaction, to achieve basically the same thing.
The idea of non-pulsed nuclear rockets is also not dead and NASA is working on such a system right now that could be tested in space by the year 2025.
If we ever wanted to send a very large spaceship to another star, a nuclear pulse propulsion spacecraft might still be one of the best ways to do it.
Project Orion was a crazy idea that wasn’t nearly as crazy as you might think when you first hear it. A lot of very smart people did the math and came to the conclusion that it could work, at least in theory.
Project Orion was a visionary concept that aimed to harness the power of nuclear explosions for spacecraft propulsion. Despite its innovative approach and technical ingenuity, it couldn’t overcome its numerous environmental and safety concerns.
While the project’s legacy persists as a testament to human imagination, like bringing back velociraptors, it also probably firmly falls into the category of things that could be done but perhaps shouldn’t be done.
The Executive Producer of Everything Everywhere Daily is Charles Daniel.
The associate producers are Thor Thomsen and Peter Bennett.
Today’s review comes from listener Brooooose over on Apple Podcasts in the United States. They write:
Short and sweet!!
Wow! Excellently written, fabulous voice, and really well done altogether. I love factoids and random interesting information to share with my colleagues and friends, so thank you!
Thanks, Broooooce! As I must constantly remind people, and I feel like I should do so again, with great knowledge comes great responsibility. Use what you learn on this podcast for good instead of evil…..unless you want to make bets with your friends and take their money.
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