Project Orion Nuclear Propulsion - 1950s Tests | Unclassified Video

Usually it boils down to ablatives. Either your pusher is designed to ablate at a known rate and factored into the propulsion calculations as fuel mass, or you are protecting the pusher plate by doing something like injecting synthetic oil that wont spontaneously boil in the vacuum of space through pores in the pusher plate so that the oil becomes a protective layer that boils off instead of eroding the surface of the pusher plate. The other method I've seen is to "go big" and scale things up to the point where the pusher plate is collecting enough force, but spread over a sufficient area that while the pusher can effectively and "safely" capture the plasma debris from the pulses while keeping the flux of high energy photons low enough that it doesn't erode the pusher plate from the radiation flux. The "Medusa" design scales this up to the extreme, putting the explosion ahead of the spacecraft and using a giant spherical "sail" to capture the energy from each explosion, if you simplify Project Orion as "explosion under pogo stick while you stand on it", then the Medusa design is "explosion above your head while you wear a hard hat, holding onto an umbrella with a pole made from elastic bands". Detail link and link Since you mention the tests with conventional explosives, I love bringing up the actual tests that were done when people talk dismiss Orion as an impractical idea that wouldn't have worked, seeing the "Hot Rod" fly powered by RDX explosions is usually enough to

Orion was essentially an "external combustion engine". I.e. you have a huge piston that is driven by repeated explosion of nuclear bombs. With a spring mecanism to even out the whallops. And no "engine block" around it. It did not generate electricity, and given the discrete/pulsed nature of the mecanism, I have a hard time seeing how you would "even out" the output, should you decide (somehow) to attach it to a generator. Let alone imagining how you would transport said electricity back to earth. Because, don't forget, it was possible to have an external combusion engine because it was in space. Even by 50's standards, the project was judged a non-starter for atmospheric flight, from environmental standards point-of-view. The project itself was in theory viable for it's original objective (space travel), but highly impractical. It requires massive, robust structures (read 'heavy') that can resist very high impacts. Not a problem once you're into space, but you have to get it into space first. And no-one will let you blow up a couple of scores of nukes in the atmosphere, on a recurring basis. The thought of launching hundreds of nukes into space to a ship built in orbit is not exactly an easy proposition either. Still, should an extinction-level meteor ever show it's face, it would be useful. For fun : some original footage of the prototypes in flight (using high explosives) ▶ this video

> Project Orion Here is some declassified test footage of Project Orion. I don't believe any of the test crafts used nuclear explosions, but you'll get the idea from this footage (on why it's a terrible idea that could only exist in the 40s or 50s) ▶ this video

Actually we do know it would work. The fundamental physics are sound. A pusher plate can in fact transfer net positive momentum from a series of explosive shockwaves detonated aft of the pusher plate in the desired direction of travel. There’s plenty of video footage from the Hot Rod tests showing it working. ▶ this video The hot rod test article was actually donated to the national air and space museum unfortunately it is not currently on display. link And for the realities of scaling up from conventional explosives to nuclear detonations you can read a little more here link and link (scroll down till you get tot project Orion and they have a pretty good summary) And the Project Rho information has links to lots of the technical details and material as well if you want to learn a lot more.