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Standard Space Habitats

halcanary.org

44 pointsluu43 comments

The subtitle of the article is a better title for the HN post.

> A refinement of O'Neill's colonies.

Basically just increasing the robustness of an O'Neill colony by removing the windows and giant mirrors. Also bolted on the power generation and cooling requirements that the original design mostly overlooked. I'm not sure the cooling requirements have been fully considered however, since it involves pumping hot coolant through 32+km of pipes. As described the colony is going to have a hot side and a cold side.

And honestly, the O'Neill cylinder is going to be covered in gold foil. I fully agree that the windows and gigantic mirrors are not a good idea. Electric lights run off of a massive solar array avoid many of the problems of the original design.

The back side of solar arrays make for good radiator placements. I dont see any reason why all the solar arrays and radiators need to be on opposite ends, why not have both on both sides?

If the habitat is segmented and connected with non rotating couplers then you could mount solar on each coupler. The design would then be multiple identical potentially self sufficient modules that can be assembled into a large colony and expand as needed. Wouldn’t have much of a horizon though so it would feel a bit claustrophobic.

Why bother connecting the solar arrays to the habitat? Just hook them up to microwave transmitters and beam the power to the cylinders. That way you can have the solar arrays anywhere it's convenient, maybe even in position to shade the entire colony so that the heat disposal problem is less of an issue.

Fair point but you needn’t bother with microwaves when a cable and some good ol’ fashion brushes will do. It’s just a rotor after all.

Maybe it would make sense to set up the solar array like a huge umbrella on the sun-facing side of the colony. Then you can cover the now-shady outside surface with radiators.

I assume we break up the colony into at least two segments so they can be counter-rotating.

Forgive me, what is the benefit of having counter-rotating segments? Does it reduce the overall angular momentum of the object...?

No, but it prevents precession IMO.

If you remove the windows, the O'Neill colony won't be as cool. We must invent some sort of transparent steel that is also effective at blocking radiation.

To be clear, you're requesting a material that is optically thin in the narrow range of EM radiation that is human visible but relatively opaque otherwise. Obviously particle radiation in general is just blocked by matter. However transmutation the material undergoes has to /also/ maintain these properties.

I can't think off the top of my head why it would be /impossible/ but it'll definitely be an engineering nightmare compared to good camera feeds and a few scattered "Star Park" type facilities.

Ahem, I think you mean transparent aluminum.

So, sapphire.

That's the ticket laddie.

One of the major observations in Kim Stanley Robinson's Aurora[0] (which is excellent, well-informed, and worth a read) is that "99.9%" self-sufficient isn't going to cut it, at least for a multigenerational interstellar mission.

[0]: https://en.m.wikipedia.org/wiki/Aurora_(novel)

Well of course not, but building colonies inside the solar system is much more forgiving. In fact much of the potential benefit lies precisely in trade between Earth and the colonies.

Maybe there can be some of the advantages of a system sent along. A multigenerational fleet with multiple ships, capable of trading among them, but also providing a degree of separation and differentiation. You could even try attaching some engines to asteroids and comets full of useful materials to send along side the fleet, ready to be used if the self sufficient systems fail, and for the colony when they finally arrive.

The gnawing, intractable loss of genetic diversity in a spaceship ecosystem made for an interesting conflict source.

Reading Diaspora right now from a rec on hn and just loving the intentional handling of conflict in that as well.

Another good point from Kim Stanely Robinson is 2312's constructing habitats from hollowed out asteroids. Way easier than refining and moving so many tons for steel to build a habitat from scratch.

I also love the ecological designing of each habitat -- whether to go with recreating a (likely lost) natural habitat or to create a new "Ascension".

Steel is a poor material for radiation protection (because of high energy scattering effects causing secondary high energy particles - but I am no Physicist). Hyrdogen rich (eg water, polyethelene, etc) make better shielding.

See also this paper on a potential location that requires little or no shielding:

http://space.alglobus.net/papers/Easy.pdf

A related paper proposes a faster rotaion (upto 4 rpm) vs. the conservative 2rpm selected in the '70s which allows for smaller (easier, cheaper) colonies to be built sooner.

I was hoping for something a bit more innovative or comprehensive, this seems to be just an oneil cylinder with no windows.

This video might be interesting for you: https://www.youtube.com/watch?v=gTDlSORhI-k

Right. They justify this by radiation and impacts, but without giving any numbers. Those were certainly considered back in the 70s. https://en.wikipedia.org/wiki/O%27Neill_cylinder#Atmosphere_...

Aren’t O’Neill cylinders with liquids inside inherently unstable?

If memory serves you have to spin them along another axis or they will wobble and then flip.

Addendum: If you like Space art (including a possible rendition of the Kalpana 1 and 2 designs) visit

https://spacehabs.com/

I don't get why "if [the diameter] is an order of magnitude larger, the structure won't hold together when it spins". The centripetal force is the same, 9.8N/kg, so it's kg / m^2 that matters. Right?

Wikipedia lists other design updates: https://en.wikipedia.org/wiki/O%27Neill_cylinder#Design_upda...

It's similar to making a taller building. You end up supporting more weight as the structure grows in height. Diameter in this case being similar to height.

I wonder if interspersing non rotating segments could allow a larger diameter. Not sure how the bearings would work or if they could be strong enough. Magnets maybe?

One has to consider how you replace the bearings when they start to wear out. It's a moving part, it's going to wear out.

Imagine cutting a cylinder in half from top to bottom, then taping the halves back together. As you spin it, the tape has to stop the two halves from flying apart. If you make the cylinder bigger and keep the centripetal acceleration the same, the tape has a harder job do because it has heavier things trying to fly apart.

Every strip of the cylinder has to keep the opposing halves from flying apart. For a big enough cylinder, the material will not be strong enough. You can make the cylinder walls thicker, but now you've made the flying-apart halves heavier too.

But if you just consider equal size strips, with the larger cylinder just having more of them, then the force on each will be the same... unless you're saying the imaginary tape have to deal with forces from other strips. I don't see why

not that its practical but if you have cylinder halves of enough mass then gravity will hold them together

But then they wouldn't be rigid enough to maintain their shape under gravitational forces... and we've invented a planet :-)

I believe habitat with natural light and view of the stars will be much more attractive than without.

The windows could contain sandwiched several meters of clear water for radiation/meteor protection, with self-sealing chemicals/a system to continuously automatically repair leaks. The water will also provide emergency water supply and thermal stability.

Another person addressed the window material problem (the tech doesn't exist).

Given that, I think it would be more attractive to have more spacious interiors, namely higher ceilings and wider corridors.

Alexis Gilliland explored similar ideas in more depth and with interesting politics alongside, in "Revolution from Rosinante" and two sequels. Recommended. (Available as an e-book.)

The usual question would be: how would one build such a structure. And why should someone create the infrastructure to do so in the first place?

> The frequency of revolution is about two minutes

period

Hmm, yes, I think you are right. Revolutions from standstill every two minutes might be a little uncomfortable in the long run, but certainly would be entertaining for a short while. Much like a washing machine.

How do you make war between habitats?

High speed rocks.

Coated in vanta black

War inside habitats is more likely. Would probably be something crude and tribal.

In giant mech suits.

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