drevilDec 5, 2023

Was reminded of Project Orion by a Ben 10 episode, and saw this bad boy. I am a smooth brain about this shit, and I don't fully understand how you'd even produce antihydrogen at scale, but if there's one cool sounding and completely unnecessary technology that dipshit billionaires could waste billions on tax payer's money it should be this.

https://en.wikipedia.org/wiki/Antimatter-catalyzed_nuclear_pulse_propulsion

Antimatter-catalyzed nuclear pulse propulsion - Wikipedia

Show threadFelix_BardnerDec 5, 2023
@chickfilla You don't need antihydrogen, you only need the antiprotons for this to work since it either relies on blowing heavy nuclei apart, releasing way more neutrons than ordinary fission per atom in the case of fission or just the energy output of the annihilation for fusion. Normal magnetic containment will work, since antiprotons are charged.
Nuclear pulsed propulsion isn't a new idea, it just hasn't been pursued because SOME people think mass producing low-yield nuclear bombs is a BAD idea. This addresses that problem by eliminating the need to use bombs at all, the antiprotons force something that ordinarily would never be able to go critical to go strongly prompt critical. You need way less antimatter than a normal antimatter drive for it to work, you're able to use much smaller pulses helping even out acceleration, and the engine performance is still really good. It's still definitely a drive you'd only ever use in vacuum, using one of these to launch from earth would be disastrous, but for things like rapid interplanetary transits or sending things interstellar it wouldn't be a bad choice.
I never liked the use of the term "catalyzed" for these reactions, I don't think it fits. While the antiprotons are helping the reaction, they are being consumed, which a catalyst typically isn't. "Initiated" or "driven" or "ignited" work better.

While this is all fine, really this engine is something that only becomes useful once you have enough infrastructure in space to want better ways of quickly sending things between planets. In the near term, the main bottleneck is sending things between earth and earth orbit, so I think billionaires should waste money on a lofstrom loop instead.
https://en.wikipedia.org/wiki/Launch_loop
Launch loop - Wikipedia

Show threaddrevilDec 5, 2023

@Felix_Bardner that makes sense, and also to my understanding (and again, all of my surface level knowledge is from Wikipedia articles so forgive my ignorance), finding Uranium on the moon or the asteroid belt would be very difficult so having a self sustaining fuel facility in space for nuclear pulse engine is probably a nogo. But wouldn't this also apply for Iridium? Can you make antirpotons without it?

As for the Lofstrom loop that looks fucking cool, but I wonder how practical it would be compared to something like a skyhook

Show threadFelix_Bardner
@chickfilla Finding decent sources of uranium on the moon is probably difficult, because the moon formed as a molten lava ball that allowed heavier elements to sink to its core, and it also lacks mechanisms to concentrate whatever is left in the crust into ores like on earth. (Double checking https://en.wikipedia.org/wiki/Lunar_resources seems to confirm my suspicions) Asteroids on the other hand can be a good source because some of them were never part of a body large enough to undergo that kind of differentiation in the first place, so they're essentially an even mix of the starting materials available in the solar system. Even better, other asteroids are made of the cores of bodies that did form and start collecting heavy elements before being utterly obliterated, which means the whole asteroid is essentially made of heavy metals. The majority of this will be iron and nickel with a dash of cobalt, uranium will still be a tiny percentage despite being concentrated since it's just a rare element in our system, but the combination of the sheer volume of material, the high concentration of useful bulk metals, and the fact that a little uranium goes a long way means that it'll be a useful byproduct from normal mining operations. I'm not an astro-geologist, but I'd suspect planets and moons that had or have more interesting chemical / volcanic activity would be better places to hunt for ores, since odds are much higher they'd be able to churn and react things around, forming more concentrated ores like on earth.

You don't need iridium to make antiprotons, other natural mechanisms like cosmic rays produce them without it. If it turns out that iridium is crucial to mass manufacturing antiprotons, that's okay because while iridium is rare in earth's crust, it's much more common in asteroids to the point that a global sediment layer rich in iridium is how we figured out an asteroid wiped out the dinosaurs. The limiting factor is more than likely just going to be power for your accelerators and traps.

As for lofstrom vs skyhooks, they actually compliment each other quite well. Skyhooks can't reach all the way down through earth's atmosphere, so you need a spaceplane in order to grab the end of the tether and catch a ride. In order to protect it from space debris, a lofstrom loop only goes 80% of the way to space, so anything launched into space by one would be on an elliptical orbit with a perigee at whatever altitude the loop sits at, and would need another little push at apogee to put it in a proper circular orbit. A skyhook is perfectly happy dipping down to lofstrom altitudes and nabbing a payload, plus because the loop is doing most of the accelerating work, maintaining the hook's trajectory would be easier. Overall, loop + hooks is basically peak highway to space material.
Lunar resources - Wikipedia

Dec 6, 2023 at 2:50amWeb