Re: Real Life Thrust (was: hyperspace)

Daryl wrote:
>This is my first post to this list ... so be kind :-).

Heh, heh.  Welcome aboard. :)

>So I'm not sure what it's possible to have a system that follows are
>current day view on how physics works and still not consume any fuel.

I think the previous post was for minimum fuel useage, not zero fuel
useage.

>In particular, I seem to remember reading about a system that used
>radioactive decay for it's thrust.  You took a chunk of radioactive
>material and surrounded it on three sides by shielding and just let it
>decay ... the particles thrown off during it's "decay" resulted in a
>miniscule amount of thrust which would last a long long time.

Haven't heard of this one yet.	AFAIK the natural decay of any
radioactive
element on earth would be highly unlikely to provide the actual thrust
for a
spacecraft on it own.  The only use for such a device I have seen is the
RTGs used aboard probes and satellites.  Its primary purpose is to
generate
electricity for onboard systems.

>Also, something to think about, the net kinetic energy stays the same
>in a system ... so if you could throw a miniscule amount of mass out
>at close to the velocity of light you could probably keep a sizable
>amount of thrust up for a pretty good period of time before you ran
>out of fuel (sorta a particle accelerator/rail gun down the center
>of your ship).

Mass driver type drives have also been discussed in cases where a ship
might
latch onto a large body of rock/dirt, mine its contents, and expend the
smaller mass portions for thrust.

>Actually, thinking about it, a perfectly efficient
>laser (converting mass directly to light) would probably be the most
>efficient thrust mechanism (but that's entering the realm of
>speculation).

I remember some scientists discussing a laser powered craft some time
ago,
not to mention in sci-fi novels.  I always wondered what might happen if
something strayed in its path.	Many authors only described it for use
in
initial acceleration, due to beam convergence problems and enormous
energy
requirements for the laser.

Mike Miserendino