(sanman) writes:

(Karl Hallowell) wrote in message . com...
I seem to recall that excluding fuel, these drives produce 100-1000
times less thrust than the force exerted by gravity on the drive
itself at the Earth's surface. Hall effect thrusters have more thrust,
but I don't think it's more than a factor of five or ten improvement.
Many current drives are intended to operate continuous for months or
years at a time, or for station keeping on satellites that stay in
orbit for years (ie, need an occasional boost to stay in position).

Another significant problem is that ion drives and hall effect
thrusters can only work in near vacuums. I just don't see this as a
technology that can work on Earth.

Alright, what about ion thrust for a craft shuttling between the lunar
surface and lunar orbit? That's effectively vacuum conditions, and the
gravity is less.

Still too wimpy. Typical ion drive thrust-too-mass ratios limit ion-drive
spacecraft to accelerations of less than a milligee; hence, at most you can
lift off smallish asteroids in an ion-drive spacecraft. To lift off the Moon
in an electrically-propelled spacecraft, you need somthing with a much higher
thrust-to-mass ratio --- say a plasma drive, or at least a resistojet...


I mentioned the fullerene fuel, with its higher molecular weight,
being able to proportionally increase the thrust. I'd imagine that
buckyonions, being concentrically layered buckyballs, would have even
higher molecular weights.

....However, unless they all have =EXACTLY= the same atomic weight, and can
be given =EXACTLY= the same charge (or at least, that they all have exactly
the same charg-to-mass ratio) they will be very poor propellants for an ion
drive, since ion drives are very picky that way...


-- Gordon D. Pusch

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