Hacker News Reader

Comment by perardi | Hacker News Reader

We are not even a teeny tiny bit close to being able to replicate an environment like that in space. Waterfalls? With what gravity? Insects and exotic plants? You mean the invasive species that came to dominate Biosphere 2?

And even if we could replicate that level of Biosphere 2…well guess what? Everyone still went nuts anyways.

https://en.wikipedia.org/wiki/Biosphere_2#Group_dynamics:_ps...

They went bonkers in a sealed bubble on Earth, with Earth gravity and Earth diurnal cycles. How would that possibly be easier on a planet where you’d have the innate factionalism in human interactions combined with the grinding stress of living on a world that wants to kill you?

View on HN

I don't think anyone would expect that - but the goal in space is not to replicate as much of the Earth biospheres variety in a closed system, but to feed a couple people for as long as possible (but not necessarily indefinitely) with the materials at hand.

I think a vat-grown culture of highly nutritious fungi (or algae or whatever, I'm no expert and I don't pretend to have even an SF writer's level of understanding of the subject) would be a much more viable solution.

It's only one part of your argument, but:

> Waterfalls? With what gravity?

Mars has gravity, and any serious space habitat would have a rotating section to simulate gravity.

Yes, on that one I should have said “within a ship or station”.

But within that domain, my point still stands. We have no plausible way to construct such a ship or station that produces significant pseudo-gravity by rotating. Building such a thing is basically impossible with anything we can manufacture—building a “wheel” that can rotate fast enough and be large enough to not cause wild motion sickness and have the structural integrity to hold enough mass to sustain an ecosystem is beyond our materials science, and would be impossible to lift into space.

> would be impossible to lift into space

Why on earth would you try that?

Exactly, while an interesting exercise, that would be insane!

But built from Lunar/asteroid material ? Sure, you can build 8 by 32 km cylinder from steel with dirt for shielding with that has a standard earth gravity just fine. No exotic materials required:

https://en.wikipedia.org/wiki/O%27Neill_cylinder

> rotating section to simulate gravity.

thats an interesting one. Humans can only just about tolerate rotation rates of about 1 rev/min or slower or get dizzy. That means the radius of such a rotating habitat has to be quite large to achieve any meaningful acceleration, which leads to its own challenges.

For example, to achieve 0.5g at rotation rate of 1/60 per second requires an arm length of 0.5 x 9.81 x 60^2 or about 10 miles. If you tentuple the rotation speed, ie 10 revs / min, you still need a radius of 180m

I believe you're missing a factor of 1/(4 pi ** 2), which gives a 446m radius for 0.5g @ 1RPM.

A have been thinking about all the things you could do in an aqua-park on a sizeable habitat in the zero-g section. Circular rotating pools - hello up there! And think about all the slides - possibilities are endless! :D

Reply on news.ycombinator.com