lunar poles, orbits, trajectories

From: spacesettlers@yahoogroups.com
[mailto:spacesettlers@yahoogroups.com] On Behalf Of Dan Wylie-Sears

> If you can't be assured of launching with either enough
> accuracy to reach your catcher

No, I'm satisfied that accuracy is not a problem, assuming the presence,
miles downrange, of position sensors and electrostatic deflection plates
(and use of achromatic trajectories).

> or enough speed to have lunar escape, that's a problem for
> any mass driver launching dumb-rock payloads.

No, I'm also sure that speeds in excess of lunar escape can be achieved.
But if my understanding is correct, any launch short of lunar escape is
going to result in the payload coming back into the close vicinity of
the launcher, barring either capture or a second impulse to modify the
orbit. The only exception I can think of is a Trans-Earth Injection
trajectory, and only that one because by the time the payload had
completed its figure-8, the moon would be in a different position.

> Even if you're launching toward L2, what if your last
> section of the mass driver malfunctions? Could that put
> your payload into an orbit where it can hit you?

I'm thinking if you arrived at the L2 point with anything above 0
velocity, you will pass through the point and no longer be orbiting the
moon (though you might still be orbiting the Earth-moon system). But
with regard to mass-driver malfunctions, I remember O'Neill mentioning
that there would be "spare" coils toward the end of the launcher which
would normally remain inactive, but would engage if there were coil
failures anywhere along the length of the launcher.

Regards,

Mike Combs