starship-design: Rocket Powered Starships...

["L. Parker" <lparker@cacaphony.net>]

Just how limited are rockets for interstellar travel? Although rockets are
reasonable for journeys into orbit or to the moon, they become unreasonable
for interstellar travel. If you want to deliver a modest size payload, say a
full Shuttle cargo (20,000 kg), and you are patient enough to wait 900 years
for it to just fly by the nearest star, here's how much propellant you'll
need: If you use a rocket like on the Shuttle (Isp~ 500s), there isn't
enough mass in the universe to get you there. If you use a nuclear fission
rocket (Isp~ 5,000s) you need about a billion super-tankers of propellant.
If you use a nuclear fusion rocket (Isp~ 10,000s) you only need about a
thousand super-tankers. And if you assume that you'll have a super-duper Ion
or Antimatter rocket (Isp~ 50,000s), well now you only need about ten
railway tankers. It gets even worse if you want to get there sooner.

Marc Millis, "Warp Drive When"



"People do love to go to weird places for reasons we can't imagine -- mostly
because they have too much money."
                            - Freeman Dyson