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It's about momentum, not energy. Near Earth, you can get energy from the Sun quite easily, or fuel a nuclear reactor with the asteroid.
Momentum is gathered by throwing reaction mass around. And reaction mass is what asteroids are made of.
> The drive technology violates conservation of energy
Do they explain it somewhere? I always got the impression it was a kicking-ass nuclear fusion engine.
I'm not sure if you're being deliberately obtuse. Momentum does absolutely nothing for you by itself-- it does not even affect penetration depth of your asteroid.
The only thing momentum does is that it scales with speed (hint: like kinetic energy).
If you have enough fuel for a nuclear reactor to throw pieces of asteroid into space, then MAAAYYYYYBE just launch nuke at the planet?!
Because that is:
1) Easier to build
2) Simpler
3) Harder to detect
4) Harder to defend against
edit: Sorry for the tone. This whole topic just really infuriates me because I absolutely can not understand how anyone with even elementary physics education could ever defend this concept as viable...
And mass...
If you have a fixed amount of energy, the amount of destruction you can create on your target is a complex function of how much delta-v you need. But the maximum is never on the extreme of "just emit all the energy there at once". It can always improve by adding some mass.
On those other comparisons, you probably have a point, assuming the people tech looks like the things we can imagine at realistic sci-fi.
And remember, you got time to build up momentum, a ion drive accelerating in a spiral with swingbys, with one final push, can get you pretty high on the C if you dont want it right now.
And i was not referencing the expanse. I was referencing todays solar driven ion engines. Boring tech. Marathon tech. But given enough time it can move a mountain up a notch, without drag.
No. You're not even getting close to your ion drives exhaust velocity, which is <100km/s.
So you are not accelerating ANY kind of asteroid for more than ~10km/s, because the closer you want to get to your exhaust velocity, the harder your scheme gets slapped down by the rocket equation-- "unlimited energy over time" does not even enter the equation.
So what you are left with is the option of finding an asteroid that you can get into a collision orbit with earth as cheaply as possible.
Even to just break even with the weakest nuclear weapons, you need at least 500 metric tons at 20km/s. You'll probably need something around 300m/s of delta-v (that would be a mars/earth transfer).
And this needs to happen quickly, because there is no stealth in space and everything you do can be observed and reverted (leaving aside the fact that any weapon system with a deployment delay measured in years is absurdly impractical).
Very far from practical. Such a plot would probably take centuries at least to carry out with reasonably conceived technology.
No its not?!
Simply getting a flyby from one planetary orbit to another is exactly the kind of expensive that I'm talking about, and thats basically what you get on impact.
There are books that are WAYY farther from our current techlevel, like Murderbot Diaries or Ancillary Justice, which handle this much better. I just don't see how adding pseudoscience improves ANYTHING-- better to just gloss over it.
I think it's fine to take scifi tech with a grain of salt; most authors skip the absolute technical details so we just have to assume that things work in some way we don't currently understand. Someone did the calculation for the Epstein and it doesn't look great: http://toughsf.blogspot.com/2019/10/the-expanses-epstein-dri... but only based on the vague technical details provided in the books.
The Jean Le Flambeur trilogy is one of my favourites, it does a LOT of quantum hand-waving but the price is worth it for all of the amazing things in that universe. "This sounds so fucking cool" > "That wouldn't work irl" for good sci-fi imo. As long as they don't mess with thoroughly understood concepts and rely on "things we don't know yet".