In article ,
(Charles F. Radley) writes:


Assuming a spherical moon.
For non-spherical, non-ideal gravity moons, things get more interesting.

Maybe.

A lot of control can be gained by reeling the tethers in and out. A
small propulsion system might help, but it is too early to say whether
it is an essential component.

Reeling in the tether between loads (just enough to miss terrain) seemed
like the obvious idea to me, too. Therefore, there must be something wrong
with it.
Stupid question time: assuming that the cargo schedule isn't very heavy,
why would we necessarily need incoming cargo or propulsion to keep the tether's
momentum up? If we had a momentum wheel powered by a solar-electric motor
mounted in the hub of the tether, couldn't we win back rotation that way with
minimum effort? It *would* take quite a while, but if we have days or weeks
between loads, it should be within reach.
The first problem that comes to mind is the longevity of a mechanical
mechanism in hard vacuum for long periods without maintenance, but with
magnetic bearings that should be surmountable, surely? Actually, come to think
of it, the momentum wheel would probably be less of a mechanical problem than
reeling the tether in/out.