Re: Gun launched orbital systems

From: Adrian Tymes (
Date: Sun Oct 21 2001 - 12:56:36 MDT

jeff davis wrote:
> A google search for babylon gun, from the
> "BIOTERRORISM" thread gives
> At
> and
> wherein we find launch costs estimated at $600/Kg (in
> 1990 dollars) for a 200 kg payload. I
> believe--someone care to confirm?--that this is
> substantially cheaper than than current launch costs
> using conventional, ie multistage rockets, methods.

True. Current launch costs are about $10000/lb, or about $5000/kg.
However, most launch technology development is going towards reusable
launch vehicles (one or maybe two stages), with costs estimated to be
$100/lb - $50/kg - or less, *and* they can take unhardened cargoes
like humans as well.

> Two immediate obsevations. Weightlessness would seem
> to allow an EXTREMELY large dish, and the hard vacuum
> of space seems to suggest that the reflective surface
> would not be subject to oxidative degradation.
> As to size, anyone care to suggest how big is too big
> and why?

Micrometeorite and other space junk impacts. Unless you can come up
with a way for the dish to be cheaply patched. Perhaps a bunch of
sensors to detect this damage, and a leaf-like structure of veins and
capillaries to pump liquid stock dish material to any wounded sites
and patch minor holes within a day or so of their being made?

Actually, on that thought...I wonder if efficient conversion from
ATP to electricity would be possible, and if so, would it make sense
to just put living leaves out (either large bunches of leaves or, more
likely, large single leaves) and pump nutrients (including carbon
dioxide) to them, letting them gather the sunlight to power the space

> I envision the dish as spin stabilized to keep it
> pointed at the sun, with steam generator, and dual,
> counter-rotating turbine/generator units axially
> mounted, and the waste heat radiator located in the
> shadow behind the dish.

Wouldn't direct photovoltaic be more efficient than a steam

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