That is why Elon is so hell bent on making humanity multi planetary.
> These are the missing practical arguments: safeguarding the Earth from otherwise inevitable catastrophic impacts and hedging our bets on the many other threats, known and unknown, to the environment that sustains us. Without these arguments, a compelling case for sending humans to Mars and elsewhere might be lacking. But with them—and the buttressing arguments involving science, education, perspective, and hope—I think a strong case can be made. If our long-term survival is at stake, we have a basic responsibility to our species venture to other worlds.
Besides, anything at all that we can imagine hitting the earth (except a gamma ray burst or collision with another planet) would still leave the earth in a better shape than Mars is. It's entirely doubtful that humanity could be self-sustaining on Mars even in principle, it is certainly not possible with known technologies.
Citation needed.
What's the blocker here?
Energy production on Mars? Why not Solar or Simple Stirling Engines.
Food/Closed ecological systems? Hard, for sure yeah, but even not particularly well funded small ecosystems like Biosphere2 worked for several years.
The biggest issue seems psychological.
But the more you scale to reach the required resources, the more of those resources you will need - especially when you'll more or less have to tunnel your way everywhere if you don't want everyone to die of cancer in their thirties.
And one of the biggest potential limiters is water: we don't actually know how much water there is on Mars. The reserves we know for sure exist at the poles are somewhat small, and it's hard to say how much of Mars' ancestral oceans froze and how much were boiled away and carried off into space along with the rest of its atmosphere. All of the water is frozen (very hard to extract) and likely full of corrosive salts (very hard to separate). Water used in industrial processes is going to be very hard to recapture, and water that evaporates is likely to be lost forever to space (slowly but surely).
You'll also need massive ecosystems to sustain an industrial chain with 0 access to fossil fuels, since you'll need to be able to produce bioplastics and biofuels in addition to food. Again, you'll consume huge quantities of water to achieve this.
Finally, energy production will be extremely difficult, as solar panels are extremely inefficient, efficient forms of solar require boiling water compounding your water problems (and so does nuclear), and both wind and solar of any kind will have massive dust problems, probably insurmountable with today's technology.
>For a self sustaining colony on Mars you need to span a huge part of the Martian globe to get access to enough raw materials to build things like the microprocessors required for basic life sustaining devices.
I don't see any reason that microprocessors are required for basic life sustaining devices. They are certainly convenient and valuable. Even if there were required, a simple microchip fab is a known technology. Expensive but does not require new technology.
An interesting question here is how big such a colony needs to be to be self-sustaining.We have clear answers because our present complex Terran economy assumes a planet wide network of trading industrial economies. Perhaps other, smaller solutions exist but we haven't bothered exploring them here because there is no market for it on Earth. Then again I suspect that as long as Earth has an industrial space faring civilization, there will be continuous trade between Earth and Mars. We might not be able to determine how self-sufficient Mars ever is because trade between Earth and Mars may never be shut off.
>And one of the biggest potential limiters is water: we don't actually know how much water there is on Mars.
I agree with you here and it is important point. If it turns out that extracting useable water on Mars is exceptionally difficult, a self-sustaining Mars colony is much harder to create. However we don't really know how true this is. This degree of uncertainly does not support the statement given earlier that "it is certainly not possible with known technologies."
>You'll also need massive ecosystems to sustain an industrial chain with 0 access to fossil fuels, since you'll need to be able to produce bioplastics and biofuels in addition to food. Again, you'll consume huge quantities of water to achieve this.
Yep, strong agree this is why most of these architectures assume large quantities of usable water. I wonder when we get the answer to this question?
>But the more you scale to reach the required resources, the more of those resources you will need - especially when you'll more or less have to tunnel your way everywhere if you don't want everyone to die of cancer in their thirties.
You tunnel for living spaces, you tunnel for resources, a self-sustaining Mars colony will likely require a sufficient investment to get going. Part of that investment will be in energy used for tunneling. Light weight nuclear batteries and generators. Bootstrapping a self-sustaining Martian colony would be extremely difficult but taking a dependent colony and growing it to a self-sustaining system seems easier.
Probably the longer Earth sustains it, the cheaper it will be to become fully self-sustaining.
>Finally, energy production will be extremely difficult, as solar panels are extremely inefficient, efficient forms of solar require boiling water compounding your water problems (and so does nuclear), and both wind and solar of any kind will have massive dust problems, probably insurmountable with today's technology.
I don't know the science but I would assume wind is out because of the thin atmosphere. Solar might be inefficient but how much electricity do you need? I suspect you want to build farms and living spaces that can survive at least a few days to a few weeks without electricity. Low electricity usage and dependency is probably a critical component of robust martian colony architectures.
You can run nuclear on things other than water. US and Soviet Submarines use liquid metal cooled reactors [0]. Why not run underground breeder reactors on Mars, if something goes wrong collapse 5km of soil on them?
While I think fusion is going to play a big role on Earth, I suspect it won't be well used on Mars for a while due to its inherent complexity and dependence on rare materials.
[0]: https://en.wikipedia.org/wiki/Liquid_metal_cooled_reactor#Pr...
Human nature, apparently. Just about all large-scale human activities at the moment are predicated on exponential growth. We're nowhere near achieving a long-term stable steady-state here on earth. The odds of achieving that in a vastly more hostile environment are even lower.
And even people with important jobs, they would work maybe 50-60 hours a week, but consume resources 24/7.
On average, the value all humans produce in a week might not be enough to keep them all alive for a week.
To me the likely blocker is reliability/accident.
Most places where humans are on Earth, if one piece of equipment fails (say the engines fall off of your passenger plane while you're over the ocean), you survive and carry on for at least days. In space or on Mars, you're dead in minutes.