Joe Strout wrote:
Here's an off-the-cuff thought which I lack the expertise to answer in
any detail:

What would it take to focus & reflect sunlight on a lunar colony from a
series of orbiting lunar satellites? I'm imagining something where one
satellite comes over the horizon, focuses light onto our moon base
(which is in the dark of course), then as it goes down, another
satellite comes up and takes over the job. (I'm assuming these
satellites have to be in a fairly low orbit since otherwise you wouldn't
be able to focus the light to sufficiently small spot.)

Why?

I'm willing to accept a period of darkness when the satellite over the
horizon passes through the Moon's shadow. I'm just trying to get some
light (and therefore heat and power) to the base for the majority of the
lunar night.

Oh.

Can anyone fill in some more details for this idea?

It may be a case of filling in the hole for it to be buried in.
It's got some problems.
The moon has a diameter of 2000Km.
So, at best the light has to come at midnight around 2000Km.
The suns rays diverge at an angle of .01 radians, so the image of the
sun will be at least some 20Km in diameter by the time you get to the
base.
This is a good match only if your base is some 20Km square, using some
400Gw of power.
The reflectors on the satellites would need to be around 30Km or so
across.
This has big nasty problems from masscons in the moon.

What about another way.
If you built a polar station, you could probably get by with a string
of reflectors in polar orbit.

A 200m spot of sunlight, of some 30Mw power seems more likely
for a near-term base.
This can't be sent from much over 20Km distance.
Orbital velocity on the moon is around 2Km/s, so a reflector will be
in view for some 10 seconds, so you need some 180 of them.

The really horrible problem is how do you accurately slew a mirror
200m wide by well over 90 degrees in 10 seconds.
Add to this that you'r going to be needing large amounts of thrust
to keep in a 20Km orbit, and things just go downhill.

The moonbase on a circular railroad track around the moon starts to
look good