>>11808917You're acting like you cant excavate and expand them.
Not to mention you can seal off any entrance, install airlocks, lay down amended soil, and artificial lighting on a martian day/night cycle and it wouldn't be any different than living and working in a small community.
And you can still have surface domes/observation decks above ground where people can go to see something besides the walls of the habitat.
Heck, if I was building by subterranean (submartian?) habitats I'd make sure to send up many large projectors to just put things all over the walls/ceilings displays landscapes and night skies (maybe even have a live feed from a panoramic camera on the surface).
I'd install skylights in the roof of larger domes, using the outposts water supply in a big cistern on the surface to be a radiation shield so you can get some natural light in.
Also don't forget that with mars' reduced gravity you could excavate an olympic stadium underground without the requirement of too much structural support.
There are covered football stadiums big enough that clouds form at the top, so if you wanted to be really ambitious you could try and engineer an artificial weather cycle inside of your colonies. You could even have a big steam generator that uses the projectors you already brought to generate big blade runner tier holograms in the steam column.
Whenever you need to expand it's just excavating a new area adjacent to you, and connect it with airlocks and subterranean tunnels.
