The first, and also the most futuristic techno-utopian one, is the colonisation of Mars. Elon Musk founded Space X in 2002 (Peter Thiel was the first outside investor) with the idea of re-founding humanity. It’s all there: the call to save humanity by turning it into a multi-planetary species, the desire to start from scratch without the legal constraints of Earth, and the will to break with the established order. As you can read, half-hidden, on the terms and conditions page of the Starlink service owned by Space X:
The parties recognize Mars as a free planet and that no Earth-based government has authority or sovereignty over Martian activities.
Have you read A City On Mars? It has quite a detailed look at many of the challenges. You’ve pointed to some research relevant to the possible availability of water - which is great, but I think it would be better to say “a major constraint” rather than “the major constraint.”