The actual spaceship [for Mars] would be assembled
in space... 20 to 50 trips would be necessary...

the cost of making 20 to 50 trips would be huge.

But how does the cost, and time, compare with
making one trip with 20 to 50 times the total mass?


Are you asking if we could build a rocket that could carry the
equivalent of 50 shuttle payloads? I guess it's theoretically
possible, but I doubt if it's practical.

Your original question asked about the practicality of a Mars
mission that required a *massive* amount of mass being
lifted into orbit and then assembled in orbit, and I'm just
saying that it would probably be too expensive to get funded.
NASA will need to find cheaper ways of getting there.

James