Question: **The context:**

There is a population of people surviving on a lunar-analogue's surface, descended from the crew of a crashed spaceship. The rest of their society is not relevant to the question, but their technology includes cobbled together habitats and void suits that protect against some solar radiation but not all (an arbitrary amount that allows them to maintain a population, but not necessarily easily).

**The question:**

What skin colour would this select for? I'd initially say a pallid white given the lack of UV exposure, but I've recently stumbled upon research which suggest melanin provides at least some protection against gamma radiation: <https://www.news-medical.net/amp/news/20110824/Melanin-also-protects-from-ionizing-radiation.aspx>

The question is, what skintone would partial protection from gamma radiation on a longstanding permanent lunar culture select for?

For reference, this is for an art project where colour palette will be important, so injecting some realism into the skintone and working from there would be the way to go.

Answer: 
There would be no evolutionary pressure for a specific skin tone for living on the Moon, because -- even were we to colonize the Moon -- no one lives on the Moon like they live on the Earth.

That's because people will live **inside all the time**, getting their Vitamin D from either food or the interior lighting.

It's somewhat similar to white people living in Australia. You'd think that Europeans with darker skin would be more genetically successful, but they aren't. Why? Because clothes (and hats) shield them from the excess UV, while allowing enough to get to the exposed body parts.
I do not know if more dangerous rays can trigger the same reaction in the skin as UV light does, but I expect they don't. 

These people would most probably suffer lack of melanin as well as vitamin D. So they would need some sort of artificial sunlight source. Expect european people to be a bit paler if they do not attend their artificial sunlight exposures, but otherwise there shouln't be much difference. Tanning and skin color have very little to do with each other. One is a reaction of skin on dangerous environment and the other is a genetical predisposition.