The most interesting version of this that I've heard of is a "fusion candle", ie a pair of fusion rockets mated back-to-back and hovering in the atmosphere of a gas giant. One rocket thrusts downward towards the planet (ie. rocket plume going upwards), ejecting mass at greater than the planet's escape velocity. The other thrusts upward away from the planet, balancing both the planet's gravity and the thrust from the first rocket. Together they apply a net thrust on the planet, moving the entire thing along with any moons while the rocket exhaust provides heat and power for the inhabitants of the moons.
This concept is explored in a video by Isaac Arthur [1] about colonizing Jupiter (starting 26:35). The idea presented is to remove all the gas to end up with a nice rocky planet.
I love his channel, but if we had that kind of capability we'd just mine Jupiter (if we'd already used the easier to access resources) and build habitats near earth where communications latency would be reasonable and the sun would be a much better power source.
I have never seen a combination of such interesting individual pages organized in such a horrific way. It's sort of like looking into an alternate universe where the principles of web design turned out totally different from our own.
That is a depressingly accurate way to describe Atomic Rockets. But I can forgive it, because it introduced me to the NSWR. [0] And something that metal just deserves to be seen.
> The advantage of NSWR is that this is the only known propulsion system that combines high exhaust velocity with high thrust (in other words, it is a Torchship). The disadvantage is that it combines many of the worst problems of the Orion and Gas Core systems. For starters, using it for take-offs will leave a large crater that will glow blue for several hundred million years, as will everything downwind in the fallout area.
A gas core engine was tried at least on standby power levels in sixties. The experiment was called "Baikal 2" and made for testing of RD-600 and EU-610, not much info on them in English.
I myself don't think that economising on fuel is that much important. Back in sixties, enriched uranium and plutonium were still though of as extremely pricey to be expended with propellant, thus the development went an extra mile to get as much oomph out of the fuel as possible.
But thanks to few decades of military industry making u235 and plutonium production cheaper, an option with expendable fuel looks easier.
My own thinking: get a conventional expander cycle rocket engine and add hexafluoride injection past the turbine. Then, you add moderator and reflectors into the combustion chamber. Voila, a much easier solution. Even easier than a solid core reactor as your don't have to think much about reactor not melting, and reactor control — just adjust the tap on the heaxafluoride.
They talk about using a wedge-like shield. A small angle can be shielded with a long wedge structure, the large surface area of which allows it to radiate the produced heat.
The spacecraft body is then placed some distance away, to fit within the expanding conical envelope of the shield.
Additionally, the space in between can contain a large radiator. By circulating coolant through the shield its mass could be reduced, as it would not need to radiate its own heat.
Atomic Rockets is mostly focused on propulsion rather than other aspects of vehicle design.
Aside from shielding, one way is physical separation of the drive system and habitation sections. You can see this in the design of the Discovery in the film 2001 A Space Odyssey.
> Atomic Rockets is mostly focused on propulsion rather than other aspects of vehicle design.
Are you sure about that? I remember reading some really interesting stuff about effective limits of laser range there, and the sections list shows ~5x as many non-engine pages as ones dedicated to propulsion.
https://worldbuilding.stackexchange.com/questions/36732/fusi...