Lunar Elevator can be built today using commercial Zylon fiber.

On Thu, Aug 20, 2009 at 12:07 PM, Michael Edward
>
> So there is a point above the moon where a month-long "selenosynchronous"
> orbit is stable?

There are two of them, the L1 (between earth and moon) and L2 (outside
the lunar orbit) points.

Of course the elevator has to go way beyond those points to be stable.
In the case of L1 at 56k km, it might be around twice that far.

It takes 1.5 GW to drive a 100t/hr moving cable elevator off the
earth. If I got the numbers right, it should only take about 45 MW to
do the same from the moon to L1. If it were running at 2km/sec and
lifted 10% of its mass a day, the elevator and power plant might run
to 10,000 tons and lift its mass in under two weeks. It is only 400
m/sec from L1 to GEO, and that's not counting the tricks you can play
releasing the payloads down the elevator toward earth.

I don't think it makes sense to build an elevator before the transport
rate hits 50-100 t/hr from earth, but at some point it will. Perhaps
as much as 1/3 of the mass of a thermal cycle power satellite could be
heat transfer fluid made from ground up lunar rock.

Keith