Mars gives you ~1/3g, which might be enough for humans but we don't know. A spin station can give you up to 1g if it's big enough. The difference between air pr

Mars gives you ~1/3g, which might be enough for humans but we don't know. A spin station can give you up to 1g if it's big enough. The difference between air pressure on Mars and hard vacuum is not that large. The radiation point is valid but we don't really know the real world long-term biological effects and limits and it's something we need to learn before we try any of this. All forms of radiation aren't created equal. The easy availability of raw materials right on the surface is probably the biggest thing a planetary body has going for it over living in space, but if you can launch stuff from the Moon with a rail gun then shipping water, CO2, etc. up from there isn't going to be that hard. As for A City on Mars I'm generally not a fan of popular science "it'll never work" books. https://dsimanek.vialattea.net/neverwrk.htm https://dsimanek.vialattea.net/neverwrk.htm They're always popular because negativity sells and is an easy way to sound smart. Being negative and wrong tends to be forgotten, see Paul Ehrlich for one well known example. Being positive or optimistic and wrong is something you'll never live down. Humans have a powerful pervasive negativity bias.