forget mars
mars is boring, it's a giant loving rock
instead, the NSSR will colonize Venus
https://www.youtube.com/watch?v=gJ5KV3rzuagin case you can't stand that dude's voice, basically because the atmosphere is so dense and because it's actually not that bad above the acid death greenhouse clouds, you could theoretically build a floating, habitable city. in addition, the gravity is much closer to earth's (so it's healthier), it has a decent magnetosphere, and it's a hell of a lot closer. there's more interesting chemistry involved and it could be a good place to research ways to reduce global warming. there's more solar panel too, and the atmosphere above the clouds is also far better than mars's.
at 50km up, the barometric pressure is almost exactly earth's (which is AWESOME) and it means that if you use terran air or something a little lighter (perhaps a mix of helium and air), you could easily float on top of the clouds. and the temperature is only around 170C, which is obviously pretty bad, but it's certainly manageable. NASA
is taking this idea somewhat seriously.