[camiller]

There are a lot of variable not accounted for, like the mass of the ship(and cargo) you are going to attach it to. In theory it can keep accelerating as long as it has fuel, and the maximum speed would be related to the speed of the exhaust. At very high velocity we would have to account for friction with the interstellar medium, space isn't entirely empty just the density is very (very) low.

In the real world you probably have a destination in mind... and maybe want to come back. For one way mission, accelerate till half your fuel is gone, perhaps coast for a bit, then decelerate with the remaining fuel (maybe keep some reserves for maneuvering).

[samstave]

So basically, step two of getting to Mars is to setup interstellar refulling stations.

Once you get to mars, or any destination, you need fuel to get back/other things...

So assuming we have an engine that can deliver us back and forth in a reasonable time, then we need to think about deploying intermediate refueling drones... and then drones to refill them... and then how to manufacture and deliver that fuel to the various nodes...

And if we are running out of helium, on earth, we need to find the most harvestable noble gas we can in the solar system...

What are the atmospheres of the other planets made up of, specifically Jupiter, how could we slurp off its atmosphere to Bush is around the solar system?

Assuming other energy sources don’t pan out

[Armisael16]

Interstellar refueling stations don't make any real sense because you spend as much fuel rendezvousing with the refueling station as you'd get back.

[camiller]

Ideally, you find fuel at your destination, or you have to take enough with you to get back. Or you make plans to stay...