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Comment by erikpukinskis | Hacker News Reader

I've heard this "survive off planet" concept over and over, and inevitably someone points out that even after the worst conceivable environmental disasters, Earth will still be more habitable than any planet within 1000 years travel.

And I've never heard a compelling response to that, so why do people still think leaving the planet is important for our survival?

The only scenario I can think of where a radiation-soaked pocket in the Canadian mountains is less habitable than "off planet" is when the Sun starts dying. But that's not really a pressing concern.

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Who says we need to move off of this planet and on to another? See the Stanford Torus[1].

We could live in stations such as that and hop down to planets to mine new materials (or from asteroid mining) when we had to. The entire world's population could fit in about 30,000 of those stations (assuming it's designed for 140,000 people). Having the human race distributed across 30,000 stations scattered around the solar system / galaxy would certainly make the race more robust to mass extinction events.

[1] http://en.wikipedia.org/wiki/Stanford_torus

I think it's more of an "eggs in one basket" issue than thinking there's any better home for us out there.

Even during the disasters there's gas pressure and radiation shielding at least.

I agree that a (human) extinction level event is unlikely on Earth. However, from my perspective, the surivale benifits of moving to another planet is more to protect us from sudden unforeseen changes. Even if Earth is still more habitable then, say, Mars, we would have already set up and been using the infrastructure on Mars needed to survive, whereas our current life on Earth is much more dependent on planet supplied infastructure, which is at liberty to change suddenly. The other benifit is that we can take lessons and technologies applied to living off world, and apply it on world.

If we had a self-sufficient colony on Mars (or wherever), that could provide a reservoir of both population and (perhaps more importantly) civilization and technology that would allow our descendants to return and re-colonize the Earth (or rebuild its infrastructure) after a major disaster.

Even though Mars is clearly less habitable than Earth in general, the point is that the humans living there would be ready for it. If there were a disaster here that killed off most of our crops or something, society would collapse and have trouble recovering.

Given the relative conditions on Mars and Earth, the hypothetical disaster befalling Earth would have to be pretty horrendous for life on Mars to represent a positive alternative.

I think we should colonize Mars, not because things on Earth might become impossible, but just because it's another planet, suitable for some adventurous, hardy souls to colonize.

I'm not claiming that life on Mars would ever be easier than life on Earth. But there are plenty of ways in which nasty things could happen on Earth that the population here is simply not prepared for. A major asteroid impact or supervolcano eruption could cause terrible weather for years (even if we don't go all the way to the "atmosphere is a pizza oven" point), and it would be awfully tough to keep feeding our cities. At that point, most industry collapses, and we're all interdependent enough that the ripple effects could wipe out the vast majority of the human population, or even all of it.

Having a self-sufficient population on (say) Mars would make it likely that some portion of human civilization would survive such a disaster. I guess you might argue that we could achieve much of the same effect by using the same technologies to establish self-sufficient populations in safe(r) locations right here on Earth: underground or deep underwater, for example. But those would still be more affected by local disasters than a colony off-planet would be, and I feel like it would be harder to recruit people to live there (and harder to guarantee that they were truly self-sufficient). As you say, Mars would attract the adventurous. The Underground Civilization Vault would just attract the astoundingly paranoid.

We already have massive redundancy on earth: Different cities. Different continents. A supervolcano would destroy at most a few continents.

> A supervolcano would destroy at most a few continents.

Just for perspective, 70,000 years ago a supervolcano eruption in Indonesia with global effects nearly wiped out the human race (http://en.wikipedia.org/wiki/Toba_catastrophe_theory). On the basis of genetic diversity studies, it's estimated that all but somewhere between 3,000 to 10,000 people were killed.

We may think ourselves immune from the consequences of a similar super-eruption today, but for most people in the world, people who aren't rich and who can't create a well-stocked underground shelter, the risk is very high.

I don't understand why the Martians would be in a better position to re-colonize the Earth than the survivors on Earth.

Right, and I'd add that once your species has survived interstellar travel at sublight velocities, you are no longer a planetary species.

The day we have ships that can get us to new planets will be the day there's no reason to go there.

Oh, I don't know. Gravity wells provide several interesting properties, such as space and access to a large amount of a wide variety of materials.

Think of it like exploiting a very large asteroid for resources and shelter. ;)

Visit, sure, but stay? An interstellar trip would be on the order of, what, tens of thousands of years?

I value the same things you mention, but don't know how much that tells me about deep future humans. I worry our ancestors of long antiquity might think, were they inclined, "Well, surely our far future descendants will still live in trees. I mean, there's fruit, protection from predators, sweet brachiation, what's not to like?"

On the other hand, we still get fruit from trees, and they make kickass forts, so I really don't have any idea. "Gravity wells" might indeed be the kickass forts of 22,014. :)

There are lots and lots existential crises that could befall mankind. To avoid having our eggs in one basket it is best to colonize other planets. (of course there are other reasons for colonization).

Short list of extinction events: global nuclear war, major asteroid hit, deadly disease that can't be contained, skynet like scenarios if AI turns out to be possible, global warming making us go Venus like etc etc.

The chance of each of these events is very small (except probably the last one which many would say is almost certain), but why would you not hedge your bets? When colonization would be so cool - the final frontier after all.

> why would you not hedge your bets?

Because there are actual, high probability problems that we could use the resources to solve. The events you describe having a severity enough to destroy every continent on earth are so unlikely as to be effectively impossible.

I'd be happy to have a self supporting technology base on the moon so that the earth could be re-colonized.

depends - with water and sunlight we should be able to colonize several planets in our solar system - getting sustainable crops going might be a problem, but once the soil biome is established: profit!

I vaguely remember an article in OMNI about a moss you could launch at Mars to kickstart terraforming.

It was probably all heavily fictionalized, but I keep wondering what happens if some sort of mischievous version of Elon Musk really wanted to just start firing green stuff at that planet to see if any of it would stick.

Nice sci-fi idea, but the surface conditions on Mars are so hostile that the poor defenseless moss would roll over and die.

* Temperatures nearly always below the freezing point of water, often several hundred degrees lower.

* Very small amount of air pressure, 0.6% that of earth, and no oxygen at all.

* Because of the two factors above, no liquid water at the surface.

* High levels of radiation directly from space (primarily the solar wind) to the surface, for lack of a global magnetic field. Astronauts visiting Mars will also need to protect themselves from this threat.

Poor defenseless moss. :)

I don't think anyone was talking about a garden variety:

http://en.wikipedia.org/wiki/Extremophile

Some organisms can already handle the radiation: http://en.wikipedia.org/wiki/Tardigrade

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