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There isn't a single "dark side" of the moon that's always in darkness, the "dark side" of the moon is the side that always faces away from us (poor choice of name). It's fully illuminated during a new moon.

Lunar regolith would probably be quite damaging to optics. It's nasty stuff. I have seen ideas for building liquid mirror telescopes on the moon, though.

by toast021 hours ago|

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Of course the dark side of the moon is illuminated by the sun at times. But it has minimal human illumination, so that's pretty nice.

by dylan60421 hours ago|

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human illumination is nothing compared to the giant fusion reactor that would be lighting it up for 2 weeks at a time. At least on terra firma, you can view the sky nightly.

by shagie21 hours ago|

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The far side of the moon would be useful for a radio observatory where one can block the noisy Earth while taking advantage of the ability to construct large collection area dishes (think Arecibo in a crater - https://en.wikipedia.org/wiki/Lunar_Crater_Radio_Telescope )

As to the dark side of the moon, I would suggest a read of the story "A Walk in the Sun" - https://www.baen.com/Chapters/0671878522/0671878522___1.htm (the dusk terminator moves at about 10 mph (15 kph) at the equator).

by PaulHoule20 hours ago|

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In space though you can do extremely lightweight construction because structures don't need to support their weight against gravity unless they are huge enough that tidal forces matter.

Like O'Neill's research group killed off the plan with the big cylinders because you would construct solar power satellites out of plastic films with vapor deposited metal and semiconductors and these would be light enough to send up from Earth and assemble in space.

by chasil16 hours ago|

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I have read elsewhere that spinning mercury would be used as the mirror.

by shagie16 hours ago|

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The suggestions that I've seen for astronomy on the far side of the Moon have largely been about radio astronomy rather than optical. The lack of the ionosphere which otherwise blocks and distorts 10 meter and longer radio and using the Moon itself as a shield from the radio noise of Earth makes it more interesting.

Radio telescopes only need a wire mesh to deploy (rather than polished optical mirrors). https://www.skyatnightmagazine.com/space-science/arecibo-tel... has a view under Arecibo.

https://www.nasa.gov/general/lunar-crater-radio-telescope-lc...

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The liquid metal mirror telescopes https://en.wikipedia.org/wiki/Liquid-mirror_telescope are interesting in part because you can get liquid mercury temperatures near room temperature on Earth.

It's theoretically possible for the moon - https://ui.adsabs.harvard.edu/abs/2007Natur.447..979B/abstra...

    A previously proposed liquid mirror telescope, based upon a spinning liquid metallic alloy, is not appropriate for infrared applications, which will require a liquid below 130K. Here we report the successful coating of an ionic liquid with silver. The surface is smooth and the silver coating is stable on a timescale of months. The underlying ionic liquid does not evaporate in a vacuum and remains liquid down to a temperature of 175K Given that there are ~10^6 simple and ~10^18 ternary ionic liquids, it should be possible to synthesize liquids with even lower melting temperatures.

... But this seems a bit more speculative. It wouldn't be mercury and requires a yet to be discovered liquid metal that is stable for months at 175 °K.