I don't understand how spacers and spacing can exist for two seconds at a university that is supposed to be just chock full of intelligent children and experienced professors of the highest caliber. On the face of it no "colony" is possible outside of the Earth. Come on now. We would have to replicate the Earth environment we evolved in. And the Earth is a paradise with all the resources we need. How can anyone with half a brain think that the survival of the human species depends upon our moving to a barren rock called Mars? Lunacy. Or, in this case, Mars-acy. The whole idea of a space "colony" is immoral (defined as deliberately causing suffering in and the death of others) and any attempt to actually create one is likely to do nothing more than construct tech history's greatest tort factory, leading to major corporate bankruptcies and stupendous continuing and growing government expense. Understand what it would mean to "make whole" a child forcibly born on Mars and therefore deprived of its right to be born, live, and die on the planet of its origin. Parents do not have infinite rights over their offspring; and deep pockets would be hit deeply.
"Unsustainable" in the case of a Mars colony means "you run out of supplies and die when the earth based supplier stops delivering." Part of that is just that self-sustaining human-supporting ecosystems are a hard problem. Your conjecture that it's an impossible problem is hard to validate. Maybe you're right, but how are we supposed to tell that?
It is up to you to prove (your "validate") that self-sustaining colonies anywhere outside the Earth are possible. You prove the positive, not the negative. Otherwise we'd have to prove there are no pink polka dotted elephants hiding on the far side of the moon.
At best "colonists" can expect to be mining dirt all day for their requirements for water. And why is it ok to strip the surface of Mars of its soil and process it but not the Earth? Aiding and abetting the idea that a "colony" on Mars has meaning is supporting a crime against humanity. Stop the breathless boosterism for (at best and if it is possible at all, which I doubt) a miserable existence on Mars. Would you send your great grandchildren to the Gobi desert to live and force them to mine dirt, leaving mountains of waterless dirt slag behind? Imposing human misery on others is immoral. Aiding and abetting suicide is immoral and illegal.
Perhaps drug researchers can find a way to allow the original organism in some antibiotic sources, say penicillin mold, to react to the evolved bacterium, thus changing its antibacterial toxin naturally as it must have done for millions of years to keep ahead of whatever was trying to consume it. Could we let nature battle the evolving immunity issue naturally? Large tanks of naturally acquired, say penicillin mold again, with its natural genetic variations placed in close proximity to the antibiotic-resistant bacteria.
And, another thought: could drug companies herd the evolving drug resistant bacteria into a cul-de-sac where we are waiting for them by adding a "hook" of some kind to the antibiotic that they (the bacterium) would also change for - to their future disadvantage. We (humans) would be waiting with another antibiotic specifically formed to take advantage of that "hook."