Today I came across what is certainly one of the most intriguing and arguably one of the best ideas the human mind has ever come up with: Project Orion.
Project Orion was a serious research program in the late 40's and 50's dedicated to achieving rocket propulsion in a...slightly unorthodox manner. In essence, it boiled down to chucking atomic bombs out the back of the rocket and detonating them to provide thrust. Mull on that for a few seconds. This was a dead-serious project by some top physicists. The explosion from the bomb would push on a large pusher plate at the back of the vehicle that would be attached with some heavy-duty inertial dampeners causing the whole thing to act like a spring, bouncing back after each explosion only to be greeted with a fresh one for the maximum impulse. Serious calculations showed that it would take about the same about of bombs to get a wide range of payload masses, from 2,000 tons (on the order of the size of the Saturn V rockets that went to the moon) all the way up to 8,000,000 tons (on the order of the size of a small city[!]) into orbit, meaning you could launch much greater masses with the same amount of "fuel" than you could using conventional measures. How many bombs does it take to launch a spaceship into orbit, you ask? The guys in charge of the project have you covered. It would take about 800 nukes at the rate of about one per second to launch something into orbit in a manner akin to "an atomic pogo stick."
Imagine that, if you will.
Imagine being among the first crew to experience one of these. The whole point of the inertial dampener is to decrease the acceleration when the bomb goes off from a lethal 100g to a more human-survivable 2 to 4g, but that's still some significant shock. And every second for over ten minutes you'd get another one. Another interesting fact: the guys in charge of the project were worried that the random nature of the explosive fireballs might send a spacecraft off course, but were reassured when they found that the effects tended to cancel out. Well, that sounds nice in theory, but in reality it means that in addition to the jerky forward motion you'd be feeling, there'd be tiny, random, deviations each time which you know aren't going to knock you off course, but which I'm sure would be pretty unsettling anyway.
Plans for launching such space vehicles included -- I am not kidding here -- covering the landing pad in a layer of conventional explosives and literally blowing the ship far enough up into the sky that it could drop its first nuclear charge without risk of shrapnel from the nuke interacting with the landing pad damaging the ship itself. I mean, how cool is that?? The project ended up being shelved not because of the extreme amounts of fallout it would generate (the idea was never actually flight tested), but because no one at the time could think of a need to launch thousands of tons of payload into space (the signing of the 1963 Partial Test Ban Treaty also made it impossible to test. The U.S. tried to get an exemption for nuclear propulsion into the treaty, but the Russians were [understandably] reluctant).
In the aftermath of bans on open-air nuclear explosions, some people have proposed a similar idea, but one where the spaceship would be launched by more conventional means (or assembled in space) before igniting its nuke drive far enough away from Earth to be non-hazardous. It was calculated that a mission to Pluto and back could be completed in a single year using such a drive. In contrast, New Horizons, the probe currently heading to Pluto, is the fastest man-made object ever, and it's still going to require nearly 15 years to get to Pluto.
And now, perhaps, you can begin to see why I find this idea so fascinating, so captivating, so wonderfully and uniquely "out there" that I could not sleep without writing this post about it. Because when you get right down to it, really, all worries aside, who wouldn't want to ride a nuclear-powered rocket? ("Prime the nuke drive, Scotty!")