Robber Barons in Space

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> > importantly, FUEL FUEL FUEL. Not only is alot of fuel
> > needed for station keeping, it is also needed for
> > orbit raising.
>
> You're point is made here. Suppose the satellite were launched
> without fuel (or with minimal fuel) and were fueled on orbit with
> some low-tech fuel like, say, water. I'd like to know why this
> wouldn't work.

I'd like to interject with the observation that in order to get the
water to be available for refueling in orbit is going to take a lot
of resources, probably costing more than the savings from not
launching fueled satellites. To have orbital refueling is gong to
require a heck of a lot more activity in orbit in order to justify
the infrastructure investment. Satellite refueling will definitely
be a market but in and of itself, cannot serve as the sole market.

As for using water, I'm assuming you mean either superheating it as
steam and using that for propulsive effect, or splitting the water
into its constituent parts and storing them cryogenically. The first
option doesn't perform effectively while the second option doesn't
store effectively for extended periods of time and requires special
tankage to store for even short periods of time.

Further, there are no satellites in orbit that rely on stored
LO2/LH2 as onboard propellants. The existing satellites rely on
hypergolic fuels such as Nitrogen Tetroxide (N2O4), Hydrazine (N2H4)
and for the ISS and some Russian satellites Unisymmetrical
Dimethylhydrazine (UDMH) ((CH3)2NNH2.)

If we are retreiving the water from NEOs, I would prefer that they
bring back liquid methane and liquid ammonia as well.

With those three constituents, an orbital refining operation can
make the above hypergolic fuels to service the satellite refueling
industry.

Nitrogen Tetroxide and Hydrazine
2NH3 + 2O2 --> N2O4 + 3H2
2NH3 --> N2H4 + H2
4H2 + 2O2 --> 4H2O

Unisymmetrical Dimethylhydrazine
2CH4 + 2NH3 --> (CH3)2NNH2 + 3H2
3H2 + 1.5O2 --> 3H2O

TangoMan