"Fred J. McCall" wrote in message
...
wrote:

:I believe the lighter the molecule in the exhaust, the more efficient
:the engine? If so, it might be better to make pellets of silicon (MW=
:14) as we process the asteroid, charge them, and accelerate them using
:an electrostatic engine. Oxygen has a molecular weight of 16, would be
:rather corrosive in a high-temp exhaust, and is more useful than
:silicon for other purposes.

But do you really want to be spraying what are essentially high speed
bullets around where they can eventually hit other spacecraft? Better
something that isn't solid for your 'exhaust'.

Yes, but space is already criss-crossed with high-speed micrometeoroids. So
the only sensible question that needs answering is are we making a
significant contribution to an already-existing problem. At many levels of
scale, the answer is probably "no".

That said, I remember that in the "High Frontier" plan, it was proposed that
mass-drivers start out using pelletized Space Shuttle ET's for their
reaction mass, but at a fairly early point switch over to locally-produced
oxygen, which would vaporize on release. So the impression that I get is
that it's not an issue to be disregarded, but it's not a big issue.

--


Regards,
Mike Combs
----------------------------------------------------------------------
Member of the National Non-sequitur Society. We may not make
much sense, but we do like pizza.