In terms of rocketry Mars could be a little closer than the Moon with Starship because Mars has all the elements to make oxidizer and fuel.

The difficulty with Mars is latency. You get opportunities to go there every 26 months and then spend 6-9 months in transit. If you need spare parts you could be waiting for years. You want all the technology you depend on to be completely boring.

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Bender 8 hours ago | parent [-]

I might even start a little closer. Take off from Texas, orbit earth a few times and land in the Mojave Desert. Have robots build his Mars city there first to prove it out. Let humans live in it for a few years. Optimize and revise.

	▲	PaulHoule 7 hours ago \| parent [-]
		Any kind of test environment closer to home is helpful. Notably the Starship system takes at least 12x the launches to put a payload into deep space than it takes to put a payload into LEO. With those economics it might sense to build large structures in LEO, such as a flashy space hotel or a simulated lunar or martian environment patterned after a very small O'Neill colony -- recent research seems to show people can tolerate a higher rotation rate than O'Neill thought so a small Bernal sphere made entirely from terrestrial materials looks possible.