I have to admit I'm intrigued by a beanstalk out through EML-1, although you are talking about an approximately 116,000 km thread at EML-1 (likely less, that gravipotential saddle point makes for some real funky equations), far longer than a GEO beanstalk. And it would make for delicate maneuvering of s/c through the area. Besides, I'm not sure how it would adapt to the gravitational flexing of the Moon's eccentric orbit. Remember, the orbit only averages 384,400 km distance, but swings between over 400,000 km down into the 350,000s km. The EML-1 point is consequently varying in distance from the Moon, only averaging 58,000 km. It seems a bit complicated.

I really don't want to mess with the farside too much, and neither EML-1 nor EML-2 are good spots for solar power sats. The general public would be far more comfortable with the idea of a fixed beam than one that tracks across the face of the planet. Besides, the geometry would make for periodic blackouts, which while also true of GEO are much less frequent there.

Besides, having fixed transmitters in GEO allows you to generate power irrespective of what happens to the terrestrial grid because you know the footprint and where to set up the rectennas.

We do need to get started on space-based solar power. We don't need to be budgeting for an engineer's wet-dream massive full-blown array, but we do need to get started on some basic test runs to figure out what works best. Running some equipment out to GEO seems like an ideal test of a CEV's capabilities.

I also like the idea of thin-film solar arrays, and it has been suggested that rolls of mylar be shipped to the Moon for vacuum vapor-phase deposition of solar cells, which are then either draped from power towers at the N/S poles, or shipped to GEO for use at SPSes.

As a launch site EML-2 would have the greater centrifugal "throw" of the two, the question is ultimately how much do you want to muck around with the Earth-radio-silent nature of the farside?

Some kind of communications structure would be needed to carry the data back from the radio scopes, and really your only two choices are cable or a sat with a really-wide-axis halo orbit around EML-2. I'm biased towards the sat, but wouldn't be against cables. I'd be more than happy to sell the radio astronomers micro-g produced lunar-material ZBLAN optic cables to connect to the instruments. Massive bandwidth!

I agree about knowing more about the impact history, if for nothing else than to either prove or disprove the notion of cyclicality in the impact record (and if there is cyclicality where are we in the cycle?). The Moon can serve certain astronomical roles, like radio telescopes on the far side and IR Oort/Kuiper watchers doing slow sky surveys of the N/S hemispheres for out-of-plane objects. It's the kind of dull boring work the astronomers don't want to waste their good orbital instruments on. They'll be relatively cheap to operate because you'll already have a base there doing other stuff, so it doesn't cost much to send a guy out to whack it with a monkey wrench.

He3 is something that will be produced naturally as a by-product of other processes. Doing a shake & bake of the regolith at between 800 - 1200 deg. C will liberate most of the SWIEs, so you're getting H, He, O, C, N. Not much, but still relatively abundant. Some of that will be He3, which is far more abundant, relatively speaking, than on Earth. This will at at least make it cheaper for scientists to engage in He3 fusion research. UWisc is doing some really good work with fusion, so don't despair yet.

Remember, the point is not to go to the Moon to mine He3. It's to do a lot of things, of which He3 harvesting is one, amongst oxygen extraction, hydrogen extraction, Al, Fe, Ti, Si, KREEP, Th & U extraction, a bit of science, supply of SPS elements, Earth studies, NEO studies, and more.

The Moon is a greyfield for American industry and trade, a chance to re-establish a technological edge that no other country can match. We can supply the things that make the world a much better place to live at a reasonable price. The ability to do so is not beyond our grasp, and the perils of not doing so, and conceding the high frontier have never been so great.

It's not just about science.