The Other End of the Scale

(this is Part 3, more background for critiquing The Expanse; here are Part 2 and Part 1)

Let's suppose we have Best Possible Rocket, as much free fuel/reaction-mass/whatever as we want, … and we just want to get there as fast as possible? Interestingly, there will still be limits.

( Read more... )

Everything Sucks

a.k.a. Our Propulsion Methods Suck, Our Power Plants Suck, Fission Sucks, Fusion Sucks, and Antimatter May Also Suck

(This is Part 4; continued from Part 3, or you can start at Part 1

Recall how rockets work: Every $\text{d}t$ seconds we toss out some bit of mass $\text{d}m$, with velocity $v_{\text{exhaust}}$ in the exact wrong direction, giving the rest of the ship, whose total mass is $m$, a small kick $\text{d}v$ in the direction we want to go. The momentum accountants then tell us:

$$v_{\text{exhaust}}\text{d}m=-m\text{d}v$$ ( Read more... )