[hedora]

As far as I can tell, humans can't survive for extended periods of time in gravity as low as it is on Mars.

There's also the problem of surface radiation. Given that we can't figure out how to build subterranean cities at scale on earth, I'm not sure what the plan is for dealing with that.

Honestly, a self sustaining space station seems easier to achieve than a self sustaining Mars base:

You can spin the space station up to 1 G, park it behind a celestial body that acts as a radiation shield and power it with nuclear, or beamed solar power.

Maybe I'm missing something obvious about the relative difficulty of the two problems.

[bmitc]

My general sentiment is that it seems much, much easier to just keep Earth sustainable rather than trying to make an unsustainable planet sustainable. It's sort of a paradox. If we can't keep a sustainable planet sustainable, how can we possibly make an unsustainable planet sustainable and keep it that way?

[inglor_cz]

Because keeping the Earth sustainable means reaching consensus among 200 states and 8 billion people? That is a political/legal problem, and I am not sure why it should be "much, much easier" than first settlers terraforming an otherwise empty planet.

It seems wrong even to compare those two tasks. They are so different that they don't seem to have a common metric. An analogy: is is easier to stop two spouses from quarreling or to write a SHA-256 implementation from scratch? How would that even be measured?

[raffraffraff]

At least writing a SHA-256 implementation from scratch is theoretically possible. The point is, it is possible to keep Earth habitable, were just not doing that. But there is no plan B. In other words, we're fucked.

[inglor_cz]

"Given that we can't figure out how to build subterranean cities at scale on earth"

Can't we, or there just isn't any economic case for it?

Cold War militaries were certainly capable of building massive buried structures when needed:

https://en.wikipedia.org/wiki/%C5%BDeljava_Air_Base

https://de.wikipedia.org/wiki/Proto_(Bunker)

[yellowapple]

> As far as I can tell, humans can't survive for extended periods of time in gravity as low as it is on Mars.

Our only datapoints for long-term human activity are "Earth gravity" and "complete freefall". This is one of the things I hope we can answer in the near-term with manned lunar missions.

> Given that we can't figure out how to build subterranean cities at scale on earth

We know perfectly well how to build subterranean cities at scale on Earth. We don't, because it's expensive and because people tend to like having windows for natural light and fresh air. It'd be cheaper on a smaller planet like Mars (less gravity to fight against), and it ain't like there'd be a possibility of natural light or fresh air anyway given the radiation and unbreathable atmosphere.

> Honestly, a self sustaining space station seems easier to achieve than a self sustaining Mars base

You'd have the same radiation problem if not worse (and no "underground" to shield you from it; "park it behind a celestial body" doesn't really work, either, when you have cosmic rays coming from all directions - said cosmic rays being the dominant form of space radiation), but other than that, yes, space stations are more practical - and you can build 'em anywhere, not just Mars.

You could also build such a spinning structure on an airless body like the Moon or Ceres. Ceres is in fact pretty close to ideal as far as human colonization goes: low gravity (so it's easy to build there and easy to leave for other destinations), close proximity to the rest of the asteroid belt (so lots of opportunities for space mining), and it's pretty much a giant ball of water ice and hydrocarbons so we'd have everything we need (at least on a fundamental chemical level) for air, food, and water alike.

[namaria]

Look I get it, dismissing part of my comment on technicalities makes it seem less likely to play out. But the fact remains that we are clearly headed for disaster and rich people are clearly hoarding as much money as they can to prepare. To hyper focus on tearing apart just one outlandish way in which the elites might or might not seek safety is its on form of denial.

[xeromal]

I wouldn't get so annoyed by it. Nerds will nerd and pick apart trivialities. I get your point that the rich are planning for this. Whether they do it by building underground bunkers, space stations, or communities are mars is moot. I'll add though that I don't think it's worth concerning ourselves what the super rich are up to.

The rich killed Rome too and they still ended up with no society.

[bmn__]

> Given that we can't figure out how to build subterranean cities at scale on earth, I'm not sure what the plan is for dealing with that.

Some ideas and napkin calculations: https://marshallbrain.com/mars