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.
Project 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)
In 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.
The 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.
The 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.
> 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.
It'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.
> 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.
It requires something like several hundred g/cm^2 of polyethylene for adequate GCR shielding. So back of the envelope, if the crew compartment is a cube 10 meters on a side, it requires 500g x 6,000,000 cm^2 = 3,306 tons of plastic to shield. I'm not aware of any non-nuclear-pulse design that can carry around that kind of heft. Just how big are the cyclers you mention allowed to get?
It requires the shielding no matter what the transportation method is. If one wanted to build a cycler, conceptually it is somewhat similar to staging a lunar mission with rendezvous in low earth orbit. The construction methodology would be something like the following:
1. Build the base structure of cycler in earth orbit, then transfer it into the orbit you want (i.e. earth-jupiter intersecting). This would be structure, engines, shielding. This might require a couple dozen nuclear thermal boosters, or maybe it has to be phased over two launch periods and assembled in the cycling orbit
2. Assemble in earth orbit everything you want for a manned mission (food, water, landing craft, astronauts)
3. Rendezvouz that material with the cycler on its next orbit (I don't know the timing for earth-jupiter - maybe 12 years after step 1). This is a comparatively small effort, as the shielding and habitable space was already taken care of with step 1
4. live your life for the year or whatever the transfer is
5. Take your landing craft from the cycler to Europa surface
Different crews can hop on the original cycler by repeating steps 2 to 5. Conceptually you would want multiple of these cyclers coming and going, so that a crew can arrive on Europa on cycler A and return on Cycler G, only spending 5 years on Europa instead of 12. Their advantage is that the big heavy mass (sheilding) only has to be launched once, and can be used repeatedly, indefinitely.
You would assemble such a craft in orbit. Some of the proposed designs for nuclear pulse propulsion conceive of a spacecraft of truly astounding proportions. The wikipedia article on Project Orion mentions an Alpha Centauri bound design that would be 20km in diameter and 10Mt in mass.
However, now that I think about it, cyclers would only need to use the NPP engines (bombs) to get into their cycling orbits, so you might be able to get away with accelerating them while unmanned. You could design such a craft with much less radiation shielding, but still include enough to prevent cosmic rays from killing (or more accurately, increasing their cancer risk) the passengers giving such a craft a significantly larger fraction of usable mass for other purposes. Initially accelerating a Mars cycler with unmanned landers with supplies and materials for an initial colony with humans to follow could be an interesting design.
All of this is more expensive than anyone is willing to pay for, even if there was an appetite for the nuclear proliferation risk of making and then putting a thousand compact bombs on a spacecraft. Not even mentioning the risk of the bomb carrier rockets exploding and causing a 100x Broken Arrow situation.
It is for this reason that I must urge the government to immediately fund the writing of several novels about how this can go wrong and right for me to read.
Should 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
If 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.
True. But if you replace the Hohlraum with dilithium and find an anti-matter supply you can power a warm drive for FTL travel. Just need to kick it now and then.
pnpm's use of hard links is so perfect for monorepos. As far as your code knows they just have a normal, run of the mill node_modules but without the massive hit on speed and disk space.
This is all assuming that Russia doesn't resort to nuclear, biological, or chemical attack.
In a conventional war, its true. NATO, or the US alone, or even some individual NATO members on their own, would cakewalk over Russia faster than the coalition did in the Gulf War.
Unfortunately, its pretty hard to tell what their actual red line is for going nuclear which radically invalidates the preceding paragraph.
I've always felt that we should 5x-10x the salaries (Singapore style) of federal elected officials and cabinet secretaries but require them to divest their entire portfolio within 30 days of taking office and only hold securities issued by the US government, states, and localities.
What I've always kinda thought is that each congress person gets a large amount of budget to spend on staff. ~order of 10 million per congressman.
This would allow for the establishment of in house knowledge groups/ staffers, particularly with regards to policy, rather than having to rely on lobbiests. It would also reduce the churn from congressional staffer to industry lobbyist.
Or at least that's my thought. The us gov spends a ridiculous amount of money, spending more in the organization meant to monitor and control that spend. If you even have a half a percentage gain in efficiency would pay for itself.
This is forgetting the ability of congresspeople to be more responsive to constituents.
Sounds nice on first order. Are there any unintended consequences? Personally I don't think you can kill corruption you can only balance it against itself.
Im sure there are but not really aware of what they are. The one that I can think of is putting some downward pressure on asset prices when the market knows that a lot of wealthy people have to sell off assets somewhat quickly.
#seveneves