I haven’t given timelines in any parent comments. I say in a parallel comment approx “if starship and SpaceX succeed in making a base and regular support missions” in the next few decades then I could imagine Mars being self sustaining for at least emergency conditions in 50-200 years. I don’t know what “laughably far off” means. I’m certainly not saying it will happen in our lifetime I’m just describing possible timelines. The comment I responded to talked about the present motivations for Mars exploration which I think was incorrect - it has never been presented as a land full of resources as implied by the comment I first responded to. It’s about long term human goals.

I disagree that there is “nothing to gain” and in fact I think there’s a lot humanity could gain from the development of regular space travel and settlement of other planets.

"Laughably far off means" was meant to mean that we can't define a credible timeline. It is essentially impossible to do with our current skills (especially in terms of logistics and automation) so any estimate of timelines is extremely speculative. It could take 200 years, it could take 1000 years.

Overall, I believe that there is 0 reason to even attempt it for now. The Earth is in the middle of an existential crisis for human civilization as we know it, and all of our resources are required at home. We need to rebuild the global economy from the ground up in a way that will reduce global warming. Mars is no escape from this, certainly not in the next centuries.

Any cent that goes to a Mars colony would be better spent on Earth. If not for combating global warming, then at least for building self-sustaining colonies on Earth that could become a refuge for humanity if all else fails, or if we get struck by some asteroid. And this would not only buy us guaranteed survival, it would also act as a perfect model for a Mars colony is some far future - if we had actually built one on Earth, with all its requirements, building one on Mars would certainly become much easier.

Until and unless we know for sure that we could build truly permanent high-tech human settlements on Earth, there is no point in trying to in space. There is nothing to be gained from Mars if we can't build a permanent colony there not dependent on Earth resources, and we will not be able to build a permanent colony there unless we first build one on Earth.

> And there's also nothing to be gained from Mars in any reasonable time frame other than research.

There is the prestige of having your nation expand, while others don’t. It is hard for democratic states to maintain long-term goals because power changes hands every election cycle, but it's not impossible that a stable and developed authoritarian country like China could launch such a venture just to cement its status as the leading superpower. That is not to claim, of course, that that colony would be self-sustaining anytime soon.

Necessity is the mother of invention. Often this become necessary for no good reason, but once that are necessary they can be the only reason that matters.

This argument could be applied to anything that is not completely impossible, right? It essentially pre-supposes that if something is theoretically possible, humanity can do it with today's engineering practices. I don't think this is a safe assumption.

I think that’s taking it too far. We haven’t made Antarctica self sustaining because it hasn’t been necessary. But making Mars potentially self sustaining (at least in an emergency situation) is more important given the vast distance to Earth. And from an engineering and physics perspective it seems perfectly possible as long as humans can survive in low gravity for generations.

It sounds like the scenario you are imagining is something like us building a colony on Mars dependent on the Earth, and some time after having a situation where the colony must become self-sustaining or go extinct. I would say that, unless the colony has a few more hundred years of contact with the Earth to prepare for this, it will go extinct with 100% certainty.

The amount of resources and people that you would need for a colony on Mars to survive indefinitely without imports from Earth is staggering. You would need all of the highest tech industries from Earth (certainly chip fabs and robotics), large mining operations, smelters. You would need enough population to man all of these (or automation on a scale we are very far from, that could entirely handle factories and self-maintenance), and enough agriculture for this population. And you would have to do all of this with no access to fossil fuels - which also means no plastics and no access to many common lubricants. And of course, all of these things would have to be built underground, with huge tunnel boring operations required for any expansion.

This may all seem possible from a physics perspective, but it is something that would have to be planned for generations in advance, well outside of our realistic civil engineering capabilities at least. And since doing all of this with the hundred million people that would be required with today's industrial practices would likely complicate things a lot more on Mars, you would need automation at a level that our robotics engineering is still very far from.

It all seems possible to some extent, but definitely not something that could happen during a catastrophe, and absolutely not something that could happen without all of the bases being laid out from Earth (that is, it is impossible for a colony that was not designed and prepared from Earth to be fully self-sustaining to become self-sustaining once on Mars out of necessity).