5 ms·
AFAIK, the only nuclear rocket that makes sense is landing a reactor on an icy comet and using it to shoot super heated steam wherever you want thrust. #sevene
by maxcan 3y ago
AFAIK, the only nuclear rocket that makes sense is landing a reactor on an icy comet and using it to shoot super heated steam wherever you want thrust.
#seveneves
- darknavi 3y agoJust don't let it leak. RIP New Caird
- idlewords 3y agoThe Project Orion design (shoot hundreds of fission bombs out the back and ride the shock wave on a reaction plate) is surprisingly practical, and probably our only way to get humans past Mars. It's just kind of terrifying.
- lostlogin 3y agoYup, it’s scary. “A moderate-sized nuclear device was estimated, at the time, to produce about 5 or 10 billion horsepower.” https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propu...
- idlewords 3y agoGeorge Dyson (Freeman's brother) wrote a book on it that is fantastic reading.
- whycome 3y ago> Freeman's brother Son. https://en.wikipedia.org/wiki/George_Dyson_(science_historian) https://en.wikipedia.org/wiki/George_Dyson_(science_historia... Relatives Sir George Dyson (grandfather) Freeman Dyson (father) Verena Huber-Dyson (mother)[1] Esther Dyson (sister)
- idlewords 3y agoMy bad; I should have checked. Thank you for the correction!
- moffkalast 3y agoFinally, the gigahorse.
- throwaway4aday 3y agoThe energy required to accelerate a useful amount of mass to a high enough velocity to travel interplanetary (or interstellar) distances in a timely manner is always going to be terrifying. Even if it runs on rainbows and hugs the kinetic energy imparted to the payload would turn it into a planet killer if you ever rammed it into one. Managing that risk so you get the payoff without any accidents along the way is the only sensible thing to do.
- woopsn 3y agoNot building the ship of thousands of little nukelets IS managing risk.
- xwdv 3y agoNot really any more terrifying than driving around in vehicles powered by thousands of tiny explosions per minute.
- idlewords 3y agoIf someone siphons your gas tank, they're not going to be able to nuke Paris. But a nuclear pulse rocket needs thousands of bomblets the size of coke cans. That's the scary part.
- marcinzm 3y ago> size of coke cans. Not really, each one would be 6 inches in diameter and weight over 300lbs.
- api 3y agoAhh the old "devil's pogo stick."
- tomatotomato37 3y agoShould also note that the Orion design most people are familiar with is from the 60s, when the latest in engineering used vacuum tubes. Modern innovations in material science, computer assisted design, and just technology that just simply didn't exist yet such as laser ignition would permit ditching the ridiculous pogo stick pusher plate arrangement with something that's more efficient, runs smoother, and looks a lot more traditional too. I wouldn't be surprised if a modern variant looks like that one Sea Dragon concept with beefier nozzle suspension
- SECProto 3y ago> The Project Orion design [...] is surprisingly practical, and probably our only way to get humans past Mars. I don't think this is the general consensus. It is seen as one of the only ways to get humans out of the solar system, but other nuclear rockets[1], and even chemical options[2], could get humans to eg the Jovian moons[3] with TRL's much higher than Project Orion. [1] https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA [2] https://en.wikipedia.org/wiki/Interplanetary_spaceflight#Cyclers https://en.wikipedia.org/wiki/Interplanetary_spaceflight#Cyc... [3] https://en.wikipedia.org/wiki/Exploration_of_Jupiter#Human_exploration https://en.wikipedia.org/wiki/Exploration_of_Jupiter#Human_e...
- idlewords 3y agoIt's not just about propulsion, but radiation. The radiation environment in space is awful and you need thousands of tons of shielding to effectively screen a crew from cosmic rays. Moreover, because of secondary radiation, partial shielding from energetic cosmic rays is worse than none. A unique property of nuclear pulse propulsion is that the engineering gets easier the more massive the spacecraft. That leaves lots of room for radiation shielding and consumables, and makes it the only halfway practical choice for multi-year missions into the outer solar system.
- SECProto 3y ago> That leaves lots of room for radiation shielding and consumables, and makes it the only halfway practical choice for multi-year missions into the outer solar system. I disagree, one of the types I referenced is cyclers, which are specifically good for the same kind of reason. NERVA is another alternative that becomes similarly easier as you scale it up. All three types would need in-space assembly, so no big issues with any of them that way. Don't get me wrong, Orion is cool (and the only way to conceivably run an interstellar mission with known technology/physics), but it isn't necessary (or even desirable imo) for interplanetary missions, at least as far as saturn anyway.
- idlewords 3y ago
- fsloth 3y agoProject orion was super cool and I warmly recommend the book by similar name by George Dyson (son of Freeman Dyson!) who did a tremendous job of putting everything back together as well as humanly possible for an ops with very top secret components. Nukes can totally function as the energy for rocket’s impulse. Very small and very directed nukes. The directed explosion plasma wave hits a pusher plate, where very specific plasma physics play out - the plate is not vaporized but merely receives an impulse - and then there are dampers to smoothen the blow. Half of the interviewed experts were positive it would work and half were skeptical. So, it’s sort of sad they had to wrap it up due to nuclear test ban before actually being able to run actual tests. The best part? The bigger it is, the better. We could totally have gigantic nuclear space cruisers that go to Jupiter in like a week (I exaggerate because I forget the exact orbits but with ISP from nukes that bastard goes fast)
- deleted 3y ago[deleted]
- LargoLasskhyfv 3y agoYah, but that would also enable https://en.wikipedia.org/wiki/Casaba-Howitzer https://en.wikipedia.org/wiki/Casaba-Howitzer , wouldn't it?
- fsloth 3y agoIn the interviews some of the team members were concerned with proliferation of shaped-charge mini-nukes. IMO that's not a good reason not to do anything but not an expert.
- whycome 3y agohttps://www.gatesnotes.com/Seveneves https://www.gatesnotes.com/Seveneves