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Project Orion: An atomic ticket to Mars
Mark Lee Rollins for redOrbit.com – Your Universe Online
You may have read the articles recently, where NASA published data that has been interpreted that they may have invented warp drive. Someone posted a comment about NASA’s EMdrive that says the signature of the interference pattern on the EM Drive looks “just like what a warp bubble looks like.”
Now as far as I know, mankind has seen as many warp bubbles as angel’s tears, so one doubts we’ll see any warp-driven spaceships taking us to Mars anytime soon. But we could’ve been there already. By an explosion.
No, we’re not referring to Jules Verne’s “From the Earth to the Moon.” In that wildly fantastic story, a giant gun is designed to shoot a projectile/spaceship to the moon. Although it was a bit prescient: Verne chose Tampa Town (Tampa FL) as the launch point, with a Pacific Ocean splashdown (in the sequel “Around the Moon)” and the space gun concept has been tested (Project HARP). But, you could only launch non-living materials. The tremendous gravitational forces for projectile launch would essentially turn any human occupants into large piles of chunky salsa.
But we could have done it with atomic bombs
What we are referring to is Project Orion, the program that reads as fantastical as Jules Verne’s story. Instead of gun cotton as an explosive, the Orion spacecraft would have used atomic bombs as propellant. But here’s the kicker, not just one atomic bomb, but a series of atomic bombs dropped out and detonated one after the other. Each bomb would provide a bit of additional upward energy to the spacecraft. Project Orion was led by Ted Taylor and Freeman Dyson at General Atomics in the late 1950s.
Credit: Wikimedia Commons
Let’s go back to the halcyon days of youth, where one could buy all sorts of fireworks at the corner store. Our more August readers may recall a taking a coffee can (back when coffee came in cans, not Keurig cups), placing an empty can over what we called an “M-80″, lighting the fuse, and running for cover. The can was usually blown to smithereens; however, even though the can deflagrated, the intact bottom was usually sent flying up several hundred feet.
And that’s sort of how Project Orion was envisioned. A series of dropped atomic bombs would explode one after the other, and a lot of their detonation force would be directed upwards towards a very large, massive “pusher plate” that would absorb the energy and transfer it to the payload.
Why not use chemical rockets?
Well I guess one reason would be the father of the US space program, Wernher von Braun, espoused Project Orion. Here’s why. Two words: Specific Impulse.
Specific Impulse (or SI) is a measure of a rocket propulsion system’s efficiency, like “miles per gallon” (although really nothing like that); the unit is “s” for “seconds.” Whereas the SI of a traditional dual-chemical fuel rocket is about 400 s, and some funky experimental ion-drives go to 100,000 s, the fantastic Orion concept had an SI of 1,000,000 s, or more.
What does that mean in practical terms, compared to a chemical rocket? When items are launched by any system, weight is typically a factor. Every fraction of an ounce takes extra propellant to loft it into orbit. Astronaut Alan Shepard famously smuggled a modified golf club head and some balls aboard Apollo 14, and drove golf balls on the moon. Estimates vary, and although technically included in the astronaut’s “personal cargo weight allowance,” this bit of frivolity cost taxpayers over $10,000. The Orion system could loft unbelievable amounts of weight, relative to a very small weight of propellant. Original designs for Orion measured in the hundreds of tons for payload alone.
So how would Orion work?
The main ship would have a very large payload allowance for crew, water, food, beer, etc.; the smallest initial designs were 9,000 tons or 9,000,000 kg (by contrast the Mercury capsule weighed about 1,500 kg). Mounted below that would be shock absorbers between the pusher plate and the payload. This is so the energy of explosions would be transmitted gradually to the occupants. Without this, they would experience G-forces too high to survive a launch. With a shock absorber, the G-forces would be the same or less than a typical chemical rocket launch. Aluminum or stainless steel would be the pusher plate’s composition, and it would be massive as well, on the order of 45 tons or more.
The fuel would be small nuclear bombs made to detonate as cleanly as possible. How small is small? In the book on Orion by George Dyson, declassified information describes bombs “softball sized” being designed by General Atomic, at the time a division of General Dynamics.
But we have all seen examples in films (especially horrible ones) about the destructive power of an atomic bomb. How could this “pusher plate” survive a nuclear explosion, unless made of Adamantium or Mithril? One word: carbon. It turns out that a very thin layer of carbon particles suspended in oil will protect metal, even when very close to a nuclear explosion. This was discovered during what was code-named the REDWING-INCA nuclear test in June 1956. Carbon-coated steel spheres placed only 9 m from an atomic bomb were undamaged after detonation.
General Atomic even built test models to see if the drive concept would work. Although not powered by nuclear warheads, the mock-up (affectionately named “Hot Rod”) used conventional explosives dropped out the back in a timed sequence, to see if it would fly upwards. As can be seen in the BBC documentary To Mars by A-Bomb (2003), the test craft flew swimmingly.
Scale this up to something the size of an office building, crew it with 60 astronauts, fuel it with nuclear warheads, and mankind should have colonized Mars by now. In fact Project Orion’s motto was “Mars by 1965, Saturn by 1970.”
But… we aren’t on Mars
Two things killed project Orion: perception and politics.
There was a perception issue based on nuclear fallout. This was partially answered by Dyson: a properly shaped nuclear charge would blast fission products away from earth at escape velocity. The quantities of radiation released would be miniscule, and certainly far less the radiation released by tests at the time.
Credit: Wikimedia Commons
Politically, there was the concern Orion would become a platform for such things as space-based kinetic energy weapons. Also, the funding from ARPA (precursor to Defense Advanced Research Projects Agency) was cut, the Air Force was uninterested, and von Braun could not convince NASA high-ups. The metaphorical nail in the coffin was the Partial Test Ban Treaty of 1963, which put an end to aboveground nuclear explosion tests. This was regardless if the use was for peaceful purposes, such as excavation, or for launching a spacecraft.
The good news is Orion is not dead, at least not totally dead; more like “Princess Bride mostly dead.”
Orion lives on in other projects such as ICAN-II antimatter rockets or NASA’s own EPPP system (External Pulsed Plasma Propulsion). And it’s a good thing it does. Given adequate warning, an Orion system is the only means to loft enough mass at a high enough velocity to deflect an asteroid on a collision course with Earth.
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Source: http://www.redorbit.com/news/space/1113387894/the-orion-project-and-how-it-could-have-gotten-us-to-mars-050915/
