The Spaceline's long L1 station

A few years ago I evaluated the selenosync space elevator - poorly. I ended up rewriting the thing. Since then some people keep revisiting, especially, the "Spaceline". Which ties in with the lunaport at Sinus Medii.

Of the several related papers I've found, this blogpoast explores Penoyre and Sandford appendix C.2.

The notion is that a L1 station between us and Luna will float away unless counterweighted - on our side. A strong, thick cable to L1 must, then, have a strong thick cable toward the other direction - not necessarily the same length but to pull the same weight. As a side-effect of a beam this long being physically anchored to Medii [UPDATE 6/16: or close enough]: I don't think the L1 Lissajous is a thing. At Lunar apogee the L1 "halo" will be a point. At perigee, our loosened cable won't deviate far from that point. Gravity will simply stretch and unwind the cable on the side toward Earth; and if bendy enough also to the Moon. Even if the force is least at perigee, P&S say an attached station is still unlikely to need much force-correction up to a 400 km drift from the straightline.

Take the unit of measurement, such that 1 = radius of our Earth. The Moon's semimajor is around 60, eccentricity-allowing. Our mutual L1 is at 51 (85%ish); GEO is 6.6.

I recommend to attach at L1 a rotating cylinder. Start with a single one: there's no need for a counterspin. And this cylinder isn't high, from its axle to the rim. Instead the L1 plateau is suited for length. Tethered to the spaceline it's not floating away. It's not Hyperion and we certainly can't have Janhunens wrapping themselves around the axle; I'm thinking, that classic O'Neill cylinder. Which we can chain as long as the weight of one be balanced by that of another.

I pondered making this long tube an integral part of the tether itself but then I started thinking of ball-bearings or, failing that, how we'll radiate the heat off; or even how to build it. So we'll just tether it until someone else figures all that out.

As to what this station buys us: it's the cheapest point to launch high-Earth-orbit cargo to stations in TLL4 or L5. As well as TLL2 on the far side of the Moon; and from there, the whole Solar System. Lunar prospectors will want a station to regrow their bone-mass. So: yeah, I'm expecting this to be where the Medii colonists actually live.