laser propulsion

--- In spacesettlers@y..., "Brad Walsh" wrote:
>
> >The guy described a system of using a 100 Mw
> >laser (cost: around $1 billion, dropping at 30% per year >in price
> >currently) used to point at hydrogen >monopropellent vehicle the
vehicle
> >uses a heat exchanger >to boil the LH upto a relatively low
temperature
> >1000C >and then chucks it out through a conventional or aerospike
nozzle.<<
> >
> >Am I correct that each launch throws away a billion
> >dollar lasar? It seems like the laser should be made
> >part of the returnable craft.
>
> No, the laser stays on the ground and fires up at the spacecraft,
if I'm
> thinking of the same project that the speaker was describing.
>
> I didn't realize though that the craft used liquid hydrogen, but
not in
> combustion. That at least is novel.

If the Hydrogen is heated to 1000C and then released into our oxygen-
rich atmosphere, I can't imagine that combustion would _not_ occur;
whether that combustion would be controlled is a different matter
altogether.

:) ed