L5 satellite workshops.

>>>>>>I was suggesting this type of shielding for habitats. The dumbell
configuration involves joining two spheres via a supporting member.
This gives you a larger radius of rotation and therefore a lower
rotation rate to give one-G (2 revs per minute is considered the max
rotation rate bearable which means a radius of rotation of 230m).

I would suggest the workshop is kept weightless - especially for the
construction of large structures such as SPSs. Of course a small
amount of gravity might be desirable for some construction techniques.

As for the rotation of the shield - I was suggesting this for the
rotating dumbell habitat. The reason for this is if you can imagine a
dumbell rotating - the shape of a stationary shield has got to at
least a toroid within which the dumbell can rotate. If we attach the
shield to the two spheres this drastically reduces it's size (it only
has to cover the area of the two spheres) and even thogh the two
spheres and the joining member will need to be stronger there should
still be a considerable weight saving.>>>>>>

The dumbell shape certainly would solve the gravity problem. It would be
interesting to conduct a feasibility study with regards to some of these
designs. Workout all of the technical details, and come up with a practical
design. Unfortunately, few on the list have enough free time. Whatever the
geometry of the workshop/hab, the idea seems practical enough. I think the
biggest technical difficulties relate to the process of delivering the lunar
material to the workshop. In my opinion, this is the weakest link of the chain.
The mass driver must deliver the payloads to a precise point in L5, at just the
correct velocity. If the accuracy of the payloads was within a few hundred
metres, then long range radar tracking would allow us to intercept them,
provided that their speed was not too high. This scenario would seem to suggest
that the payloads are best launched in a batch method, ie, as a single payload
of 20 tonnes, rather than 200,000, 100gram payloads. Unfortunately, launching 20
tonnes of material, all at once from a lunar mass driver, will require a great
deal of electrical energy. The construction of the mass driver would also be
much heavier.
Then we come to the difficulty of catching the payloads. The payloads must be
delivered with as little velocity as possible. Velocities greater than 50m/s may
damage our robotic mass catcher. The other problem relates to the momentum of
the payloads. A 20 tonne payload, travelling at 50 metres per second, carries a
momentum of 1 million kgm/s. How do we neutralise that momentum, without
consuming large amounts of valuable fuel?