This question was answered as soon as SAM released, and is still answered in-game.
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But "need" and "available" are not the same thing. Like, I don't
need Vikings settlement now that I finished it for max upgraded Yggdrasil, but it is still
available to me. Same way may go for Mars. Because you can only produce mars goods on Mars. If it's completely removed and
unavailable I cannot produce it. Ok, I have Stargazer, but goods production should not be exlclusive to any GB or anything like that, but always be available through goods production buildings.
Secondly, assuming it is correct that we won't need nor have access to Mars (I can understand that the current Spaceport will only take us to a new colony as soon as it has been researched), then that would mean once I enter SA:AB, I will no longer use SA:M good in GE nor BG and I kinda have hard time to believe that.. What would I use instead? We always use current and previous era's goods. But if we still use them, then I indeed have a further need of that colony.