[gurps] Flow of passengers, cargo, fuel: TL10 hard science space background

[David Scheidt]

On Mon, Mar 2, 2009 at 1:55 AM, Onno Meyer <Onno.Meyer at gmx.de> wrote:
> Say you have a system with one earthlike world, a moon around that
> world, a marslike world and a couple of asteroids. An specialized
> transport system might include:
>
> * Winged shuttles from the earthlike world to orbit and back.
> * A big orbital station.
> * Short-range transfer vehicles for the flight to the moon and
>  long-range transfer vehicles for the other world or asteroids.
> * Non-winged landers for the moon and the marslike world, either
>  optimized or one general-purpose model.
>
> I'm assuming that passenger flows even out - whoever goes up must
> come down again, long-term migration is too low to distort that.
>
> The same can't be said for cargo, which depends on development
> patterns. If people arrive from interstellar space, they could
> start with the orbital station and asteroid miners before the
> colonists with locally made gear go down to the worlds and moons.
> If the world is a homeworld, everything has to be lifted out of
> the gravity well.
>
> And where is the most convenient water source? If water comes
> from the world, the shuttle would lauch a payload and enough
> fuel for an OTV and a lander, the OTV would take the payload,
> fuel for itself and the lander, and the lander would take the
> payload and its fuel.
>
> If water comes from the moon, it goes the other way around. In
> a neat world, cargo and fuel flows might balance. If the moon
> exports more than it consumes, moonward flights can carry fuel.
>
> Or there could be multiple fuel sources. Shuttles refuel on
> the world, landers refuel on the moon, ice miners bring ice
> from the belt to the station for redistribution to the OTVs.

My take on this is that only things that need to leave the gravity
well leave the gravity well.  So, in most cases, that will be people,
some argicultural products (it's a whole lot easier to produce meat on
a planet, for instance, or grow fairly low density foods or fruit.),
certain high-tech  manufactured goods, and any raw material that's not
readily available in the system.  Things that are abundant in space
will be produced in space, and shipped to the planets if there's a
reason to.  If the planet has water, it will be used to get things
into orbit, but it's almost certainly cheaper to ship it in from the
comet belt, once things are settled,  (Doesn't matter if it takes 10
or 20 or even 50 years for a particular comet to get somewhere, as
long as the rate they arrive at is high enough to be useful.)  to use
for other things.

Heavy industry will be mostly in orbit, but worlds with extensive
populations will have have some of their own, on planet.  (doesn't
make sense to build ocean ships in space, for instance, even if it
does to make the steel they're made of there.)  There are also some
things that are easier to control with gravity, with atmospheric
inputs, or which can take advantage of the thermal mass of a planet.


-- 
David Scheidt
dmscheidt at gmail.com