So, basically, the rules essentially say "The outer system planets are gonna be effectively in the same spot for the lifespan of the campaign so just put them somewhere and don't worry about it. (Neptune will take 40 years to go 1/4 the way around its orbit, for example). The inner planets are the ones that are gonna be moving. Here's a couple ways to abstract their location if you don't want to have an orrery for each system."
And then some stuff on how "flight paths" between planets work, things the PCs can do if they want to ignore the computer's optimal safe flight path and roll dice, guidelines on errors that can happen like not decelerating enough to actually stop at the planet you wanted to go to. With corrective options like "The loop of shame" or atmosperic braking (if that won't get you arrested
), and other such things. Plus some considerations like how you might account for gravity slingshots, what if the players change course in the middle of their flight plan with a lot of momentum built up on the original plan, so on.
So, yes, you can use it anywhere you want. It's "What do I do if my players and I aren't into orbital mechanics maths, but we need to do something besides the straight formula?"
And then some stuff on how "flight paths" between planets work, things the PCs can do if they want to ignore the computer's optimal safe flight path and roll dice, guidelines on errors that can happen like not decelerating enough to actually stop at the planet you wanted to go to. With corrective options like "The loop of shame" or atmosperic braking (if that won't get you arrested
So, yes, you can use it anywhere you want. It's "What do I do if my players and I aren't into orbital mechanics maths, but we need to do something besides the straight formula?"