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: 
> 
> ...Realism in the skin tone...
> 
> 
> 

You have only two perspectives that would affect skin color.

1. The original ethnicity and/or races of the crew. In the 1960's this would have been white people. Today, there is better diversity. Tomorrow, better still.
2. Time. It takes time for skin color to change. Not years. Not centuries. Possibly not even millenium. It takes eons. The genetics of skin color takes a boatload of time.

If your intrepid crew's descendants haven't experienced at least tens to hundreds of thousands of years, then their location has ***nothing*** to do with their skin color. The politics and social mores of the society that launched them into space would have everything (as in 100%) to do with skin color.
Since skin colour affects appearance, sexual selection comes into play. Whatever skin colour their culture finds most attractive is what will be selected for.