Colonies in Space: Mirrors vs Artificial Lighting

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chimericoncogene
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Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

The traditional depiction of a space habitat, from Bernal Spheres to O'Neill Cylinders to Lunar Lava Tube Towns, has them as sunny, brightly lit environments, basking in the glow of sunlight reflected past cosmic ray shielding (or through tubes in a lava tube roof) via a complicated system of mirrors of foil and steel.

http://ssi.org/space-art/the-don-davis- ... r-artshow/ has a few nice-looking ray diagrams which do not appear airtight.

Image

However, from the point of view of this layman, the use of solar mirrors appears to imply a number of design tradeoffs. Mirror systems have to be painstakingly designed to uniformly illuminate the interior surface of a habitat (the solution above appears to have been an ogive light distributor, but the O'Neil farming habs appear to have some insolation issues), or nonuniform illumination can be tolerated. Mirror systems will run very hot if they run through foci. Mirror systems limit habitat geometry, and get in the way of external structures.

On the flip side, solar lighting might be more energy-and-heat-efficient, more pleasing to the eye, and straight up more powerful than artificial electrically-powered alternatives, and involve less high-voltage cabling and explosive light bulbs (depending on design).

One wonders to what extent, or under what conditions, electrical alternatives to solar mirrors might become more attractive, and what the gut perception of various other more learned members of this forum would be regarding the trade-offs involved.

Options might include covering the floor of the rotating habitat in upward-pointing super-hot one-megawatt xenon arc lamps, or hanging them from a giant chandelier, or using larger numbers of smaller devices, or LEDs, or ten-kilowatt xenon arc lamps which are the biggest I could find on google, or nuclear powered glow-lamps.

*The big space habitat is presumably is being used as a giant park/atrium to give the inhabitants of a space colony/factory a nice view when they wake up in the morning, and a place to go swimming. I really can't imagine people building such a Bernal Sphere-sized room to build factories, suburban houses, apartment blocks, and office towers full of cubicles in it, although those might line the walls or go through canyons in the floor or something, but objections to this apartment-dweller's point of view are welcome.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by madd0ct0r »

chimericoncogene wrote: 2020-04-01 03:54am The traditional depiction of a space habitat, from Bernal Spheres to O'Neill Cylinders to Lunar Lava Tube Towns, has them as sunny, brightly lit environments, basking in the glow of sunlight reflected past cosmic ray shielding (or through tubes in a lava tube roof) via a complicated system of mirrors of foil and steel.

http://ssi.org/space-art/the-don-davis- ... r-artshow/ has a few nice-looking ray diagrams which do not appear airtight.

snip image - img]http://ssi.org/assets/images/Ch06p088.gif[/img]

However, from the point of view of this layman, the use of solar mirrors appears to imply a number of design tradeoffs. Mirror systems have to be painstakingly designed to uniformly illuminate the interior surface of a habitat (the solution above appears to have been an ogive light distributor, but the O'Neil farming habs appear to have some insolation issues), or nonuniform illumination can be tolerated. Mirror systems will run very hot if they run through foci. Mirror systems limit habitat geometry, and get in the way of external structures.

On the flip side, solar lighting might be more energy-and-heat-efficient, more pleasing to the eye, and straight up more powerful than artificial electrically-powered alternatives, and involve less high-voltage cabling and explosive light bulbs (depending on design).

One wonders to what extent, or under what conditions, electrical alternatives to solar mirrors might become more attractive, and what the gut perception of various other more learned members of this forum would be regarding the trade-offs involved.

Options might include covering the floor of the rotating habitat in upward-pointing super-hot one-megawatt xenon arc lamps, or hanging them from a giant chandelier, or using larger numbers of smaller devices, or LEDs, or ten-kilowatt xenon arc lamps which are the biggest I could find on google, or nuclear powered glow-lamps.

*The big space habitat is presumably is being used as a giant park/atrium to give the inhabitants of a space colony/factory a nice view when they wake up in the morning, and a place to go swimming. I really can't imagine people building such a Bernal Sphere-sized room to build factories, suburban houses, apartment blocks, and office towers full of cubicles in it, although those might line the walls or go through canyons in the floor or something, but objections to this apartment-dweller's point of view are welcome.
1) we tolerate uneven lighting in our buildings and landscape already. Why would that be a problem? (although I know the lighting engineer on MARSHA and she considers it fundamental for human mental health)
2) Mirror systems running hot are not an issue in Lava Tubes. You have a very cold rock around you.
3) most of thee systems were proposed when the best lighting systems were very ineffecient - so providing a lot of light by them meant providing ooodles of heat. Large numbers of smaller LED devices are far far more fault/failure tolerant, and distirbute the heat load across a wide area. I think at the moment solar collection and lighting technologies far outstrip transparent material technologies.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

madd0ct0r wrote: 2020-04-01 05:58am
1) we tolerate uneven lighting in our buildings and landscape already. Why would that be a problem? (although I know the lighting engineer on MARSHA and she considers it fundamental for human mental health)
2) Mirror systems running hot are not an issue in Lava Tubes. You have a very cold rock around you.
3) most of thee systems were proposed when the best lighting systems were very ineffecient - so providing a lot of light by them meant providing ooodles of heat. Large numbers of smaller LED devices are far far more fault/failure tolerant, and distirbute the heat load across a wide area. I think at the moment solar collection and lighting technologies far outstrip transparent material technologies.
Thanks! Yeah, in hindsight even lighting is a bit overrated; people will hardly notice moderate differences.

I never really thought about transparent material technologies, but I hardly think they'll be useful when you're trying to build two-meter-thick cosmic-radiation-proof hectares of the stuff, and many rotating habitats are mostly floor, which you might want covered in football fields or swimming pools or picnic lawns or something. But many many options for space habitats exist as usual.

I think your average power output will have to be high if you want to save on space. If you want a relatively small emitting surface, and don't have much space to mount lights, power density is going to have to be high. Giant chandeliers or Wall-E style digital skies (with Ads! Glorious pop-up ads!) are probably still going to have to pump out hundreds of watts per square meter if your floor space is to be much bigger than your light-mounting space (which may be acceptable, recall Island Three wasted half its floor space on windows, or you can use giant billboards/poles to increase mounting area).

EDIT: https://www.noao.edu/education/QLTkit/A ... indoor.pdf

has a little section on light levels, which suggests you could get away with "feeling like daylight" with <100 watts per square meter at 60-200 lumens per watt. Sunlight is 100,000 lux, but daylight is only 10,000 lux. Dunno about grass and roses (and semi-decorative fruit and vegetable gardens) growing though. Full-spectrum lighting is possible with LEDs according to some gardening sites. Beaches may require extra lights, and Vitamin D supplementation is advised.

It is reasonable to expect LEDs to increase in power density in the future?
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by Solauren »

Further out in a solar system - lower temperature nuclear reactors and lightbulbs are far more productive, then a solar mirror set up.
Inner system (mercury - mars) - mirrors assisted by said reactor/lightbulbs would be better.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

Solauren wrote: 2020-04-01 08:44am Further out in a solar system - lower temperature nuclear reactors and lightbulbs are far more productive, then a solar mirror set up.
Inner system (mercury - mars) - mirrors assisted by said reactor/lightbulbs would be better.
That would probably be the case, but my guess is that it will depend on how cheap mirrors (and more importantly, mirror lighting systems - primary mirrors, secondary mirrors, diffusers, safety devices, on/off switch, heat management, all the other stuff a layman like me will miss) turn out to be relative to nuclear power and a zillion LED light bulbs.

If they are so exceedingly cheap that Mars is being terraformed cost-effectively by putting up 64 million+ square kilometers of foil mirror (total mass could be as low as 640 million tonnes - well under a cubic kilometer of asteroid - with <<Solar Sail numbers) out at Sol-Mars Lagrange 2 to char-grill Mars...

Well, the business case for using a 25x/100x bigger mirror out to Jupiter or Saturn suddenly gets a lot better.

OTOH, if every Space Winnebago mom-and-pop-rock-rat VASMIR has a 2-gigawatt nuclear reactor strapped on the back, then cheap nuclear-electric is practically a given.

I don't believe that we'll be using solar all the way out to Uranus or Neptune either, but it's probably context-dependent.

(On a side note, 64 million square kilometers of mirror will hardly be enough to turn Mars habitable - I personally think terraforming sounds pretty cost-ineffective and terraforming Mars is probably infeasible; but I digress...)
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by Solauren »

Tunnel down to Mar's core.
Nuke it to melt it.
Mars normal axial rotation will cause the now liquid core to spin, and produce a magnetosphere, allowing it to keep more atmosphere.

Soft land a few comets on it, melt them to provide water (if needed), and therefore water vapor, oxygen.
Once you get some areas (i.e caves) with atmosphere and warmth, dump a few thousand tons of good fertlized soil, with bugs, etc, off, and set up greenhouses.
Nature will handle the rest.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by SpottedKitty »

chimericoncogene wrote: 2020-04-01 03:54am I really can't imagine people building such a Bernal Sphere-sized room to build factories, suburban houses, apartment blocks, and office towers full of cubicles in it, although those might line the walls or go through canyons in the floor or something, but objections to this apartment-dweller's point of view are welcome.
IIRC (been a while and the book's in a storage box somewhere) the cylinder designs in High Frontier used the end caps for housing, industry, etc. and heavy industry that could be adapted to zero-g in non-rotating pressurised volumes outside the end caps. Has anyone looked back at those ideas to see which ones still look workable (and, more importantly, live-in-able).
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

Solauren wrote: 2020-04-01 02:25pm Tunnel down to Mar's core.
Nuke it to melt it.
Mars normal axial rotation will cause the now liquid core to spin, and produce a magnetosphere, allowing it to keep more atmosphere.

Soft land a few comets on it, melt them to provide water (if needed), and therefore water vapor, oxygen.
Once you get some areas (i.e caves) with atmosphere and warmth, dump a few thousand tons of good fertlized soil, with bugs, etc, off, and set up greenhouses.
Nature will handle the rest.
That's a lot of nukes, a lot of comets (think tens of comets 100 kilometers across each, but scale need not stop you), and a lot of uncertainties.

My amateurish proposal involves building 100 million square kilometers of mirror, figuring out the technology needed for an artificial magnetosphere (talk of mini-magnetospheric plasma sails on Atomic Rockets suggests that it is at least not inconceivable), char-grilling the poles and warming the rest of the planet, and then finding some way to introduce enough gases to Mars that does not end up blowing off the atmosphere. And hoping that the enormous amounts of liberated water vapor do not shroud the planet in a sunlight-reflecting ground-chilling white cloud. And hoping that the local Martian domes, factories and tunnels can take the rain, melting permafrost, giant torrents of water that take millennia to drain the poles and carry water everywhere (think the Mediterranean Sea Gibraltar Dam cycles), etc, etc, etc. And hoping that a zillion complicated feedback loops work in your favor.

The latest research, IIRC, indicates that most of Mars's atmosphere is just gone, blasted into space by the Solar Wind. Outgassing from the soil and poles isn't going to cut it.

Back to mirrors and windows: yeah, Island Three did have the industry in and outside the endcaps, where the radiators are, and depicted lots and lots of suburban housing and farms in the middle. But Island Three was also somewhere in the vicinity of thirty kilometers long and massed billions of tonnes. I'm thinking along Island Two lines when I say that you're probably not going to waste valuable parkland on cows and suburbia (except for mansions for the very rich).
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by Solauren »

Yeah, that's alot of nukes. It's not like we have a massive global arsenal of them being used for political advantage that could be used more productively.....

And yeah, it's alot of comets. Fortunately, our solar system is literally swarming with them.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

Solauren wrote: 2020-04-02 10:13am Yeah, that's alot of nukes. It's not like we have a massive global arsenal of them being used for political advantage that could be used more productively.....

And yeah, it's alot of comets. Fortunately, our solar system is literally swarming with them.
The exatonnage-zettatonnage you would require (I'm spitballing the number, but from the Atomic Rockets Boom Table, exatonnage is crust-melting and zettatonnage is Death Star-like) would involve maybe a million-billion times more nuclear firepower than currently exists, or existed at the height of the Cold War, or you could realistically build save mining Jupiter for deuterium.

And you don't need to restart Mars's core. https://reader.elsevier.com/reader/sd/p ... 6101EC5189
suggests that you can build a mini-magnetosphere with megawatts of power in the near future. Dunno how reliable the paper is, am an amateur. Stick one of these at Sun-Mars Lagrange 1, bingo bango magnetosphero.

And the comet diversion involves one-hundred-kilometer-wide, quadrillion-tonne small-moon-sized ice lumps which you may need to slow down before plopping down on Mars, lest you blow off the atmosphere you are trying to build up with the biggest collisions in the solar system since the Late Heavy Bombardment (this might be hyperbole). Even a few hundred meters per second of diversion is many petawatt-years (or more?) of sun-pumped laser power pointed at a laser-powered rocket the size of a volcano strapped to your comet (then again, you kinda need at least fifty petawatts to send a good-sized lasersail colony to Tau Ceti or something in a reasonable timeframe).

As usual, scale need not stop you (hey, it's sci-fi, and bigger is always awesomer!), but it just seems a lot cheaper to use those same titanic energies to turn the mass of the asteroid belt into habitats or something. A Mars terraforming project can run quite the system economy.

Nobody says such a project has to make any more economic sense than spending vast gobs of money on starflight to fulfill a vague goal of "settling the galaxy within ten million years to prevent human extinction", or, you know, space settlement in the first place. It would be so cool. But it might turn out to be very very very big.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by Solauren »

You have no idea how hard it was to read that post....

I suggest you just read this
https://en.wikipedia.org/wiki/Terraforming_of_Mars
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

I apologize for my poor writing. I've been spending too much time on internet chatrooms, and too much time writing notes.

I still do not quite understand the point you are trying to make, or the point of our apparent disagreement. I see no reason why there should be one; I merely wanted to emphasize the scale and relative difficulty of your proposal, which I think cannot be done with present technology (Also, the Wiki article mentions the mini-magnetosphere). Future technology will be bigger and better.

It is entirely plausible that positive feedback will be our friend and partner in terraforming Mars, so that only limited inputs of energy (and more importantly, matter) will be necessary for a terraforming project. Perhaps terraforming techniques that leverage those feedback loops can be implemented with present technology. However, I was under the impression that the results from MAVEN were highly unfavorable for the traditional "easy" terraforming scenarios, and that much more effort than hoped for will be necessary. The Wiki article itself cites a 6kPa atmosphere as achievable using gas presently on Mars, and a full atmosphere will need at least several times that. That does not make terraforming impossible, merely more difficult (for a certain value of "difficult"), and therefore less cost-effective.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by Formless »

Don't worry, mang, Solauren of all people saying that others are posting incoherent statements? Pot, kettle, black, he's absolutely pissing awful about posting coherently. I swear if I didn't know better I would think he's drunk posting half the time. That's why you are getting confused about the source of your disagreement with him-- its on him for being bad at communicating.

And yes, your instinct is correct, his statement that we are sitting on a fuckload of nukes is irrelevant. First, the real problem is drilling thousands of kilometers down to Mars's core, which is insane. The holes we drill to get at oil can be a mile deep and that's still not good enough. Plus they are too narrow to fit a hand grenade, let alone thousands of nukes, and you have to keep the hole from collapsing in on itself and stopping the entire project. If it were even remotely possible, its still completely infeasible. Plus, we don't have nearly enough nukes to melt Mars's core, you have to be fucking kidding me. Earth's core remains molten in part because there is uranium in it that's still providing heat from nuclear decay. Mars's core froze solid because its so small (relatively speaking) I don't think you could keep it molten even if you replaced half the iron with nuclear material. Either way, its not like its even necessary to melt the core to terraform Mars, because the planet is too small to retain an atmosphere even if you could get its magnetosphere going again. Terraforming doesn't work the way he presents it. First you need to give it an atmosphere thick enough to matter. And while there are plenty of comets in the solar system, those are mostly far out in the Oort cloud. Plus comets tend to sublimate if you bring them too close to the Sun. One argument for Pluto not being considered a planet is that it could only exist that far out in the solar system. Terraforming Mars is just a vanity project and a waste of resources. A more logical approach to colonizing the planet is with domed cities, since anything with a roof will need much less oxygen and have radiation shielding built in to the glass structure. But if you are going to make a glass domed city, why not just make more space colonies like Gerrard O'Neil suggested? After all, one of the problems with colonizing Mars is the low gravity. Earth based life evolved for Earth's relatively high gravity, especially animals like ourselves. We have no idea right now how badly low gravity will effect child development, but it can't possibly be good. So its probably better to play it safe and go with a station you can spin up to a full 1G of virtual acceleration. It might have some interesting effects on the inner ear, but it can't possibly be as devistating as what Martian, let alone Lunar, gravity would do to a child. Its not like in The Expanse where we can give you a drug cocktail to reinforce your body against a lifetime of low gravity, the skeletal and vascular system do not work that way.
SpottedKitty wrote: 2020-04-01 03:25pm
chimericoncogene wrote: 2020-04-01 03:54am I really can't imagine people building such a Bernal Sphere-sized room to build factories, suburban houses, apartment blocks, and office towers full of cubicles in it, although those might line the walls or go through canyons in the floor or something, but objections to this apartment-dweller's point of view are welcome.
IIRC (been a while and the book's in a storage box somewhere) the cylinder designs in High Frontier used the end caps for housing, industry, etc. and heavy industry that could be adapted to zero-g in non-rotating pressurised volumes outside the end caps. Has anyone looked back at those ideas to see which ones still look workable (and, more importantly, live-in-able).
It depends on the design. Most people associate Gerrard O'Neil with just a couple of space station designs; the Bernal sphere (aka Island One), the classic cylinder (aka Island Three), and if they know anything about his involvement they will know he contributed to the Stanford Torus (even though it isn't in his book). But even at the article chimericoncogene linked to there are a bunch of his lesser known designs. For example, there is the Sunflower station design (which I was already aware of) which has sort of a pill shape and works like an inversion of the Bernal sphere. The middle of the pill is all window and everyone lives exclusively in the end caps (it gets its name from the appearance of its mirror system). Then there is the Crystal Palace design which appears to be a concession to Stanford's obsession with toroids: the human living area is a bunch of shielded rings inside a cylinder and agriculture is done in a cylinder with smaller radius, hence giving it a top hat look from the side. Stanford really thought humans couldn't tolerate as many RPMs as O'Neil believed we could, but in truth the science is still out on that (the experiments all suffer from being done in Earth gravity, apparently). Finally there is the Model One cylinder, which looks at first glance like the Island Three cylinder, except it hybridizes the ideas of that station with ideas from the Sunflower and the Crystal Palace. Humans inhabit only the end caps which are heavily shielded against cosmic rays (the mirror system is correspondingly more elaborate than Island Three); meanwhile the three sectioned middle part of the cylinder is purely for agriculture. Finally, there is a sphere hanging off the back end that could be for industry or a radiation shelter, or whatever else you might want that doesn't need natural lighting. From a distance the best way to tell apart an Island Three from a Model One is the extra mirrors of the Model One that reflect light into the end caps.

And of course there are plenty of other designs that people have come up with over the years that build off of O'Neil, MIT and Stanford's ideas. In fact, there is a yearly [urlhttps://space.nss.org/settlement/nasa/Contest/]student contest[/url] by the National Space Society that used to be hosted by Nasa until 2018. One of my favorite designs to come out of it is the ASTEN design which is a beaded/banded cylinder meant for Earth orbit. The beads are for human habitation and work, the bands are for parks, and the center of the station is where industry is conducted in microgravity. But what's most interesting for this thread's purposes is the 2020 winner, as those students looked at the feasibility of colonizing the Kuiper belt with cylinder type stations (which they named the Stern habitat). Interestingly, even though their station is intended to orbit as far out as Neptune or Pluto, they still opted for natural sunlight, reasoning that a massive and complex parabolic mirror system is still more efficient than turning light into electricity and then back into light. The inefficiencies exist both at the level of the solar panel and the LEDs supplying the light, and they wanted farms to have as much solar energy as possible in order to grow food. They don't explain why they didn't consider using nuclear power, though. Perhaps its because of the specific Kuiper belt object they proposed for this station to orbit near (486958 Arrokoth). Nuclear material isn't evenly distributed in the solar system, so they may be under the assumption that they cannot rely on it so far out in space. Sunlight might get less intense out in the Kuiper Belt, but its still present and usable with a sufficiently large parabolic mirror. As for heat buildup in the mirror system, they have some interesting ideas about using benzine or other liquids with a refractivity similar to glass as a coolant to spread the heat around the entire system rather than allowing it to build up in any one place and cause damage.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by Solauren »

Formless wrote: 2020-04-03 04:51pm Don't worry, mang, Solauren of all people saying that others are posting incoherent statements? Pot, kettle, black, he's absolutely pissing awful about posting coherently. I swear if I didn't know better I would think he's drunk posting half the time.
The irony of that statement is I do not consume alchohol or narcotics of any kind. A lot of the time, my emotions simply get the best of me and things come out in a jumble.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

Formless wrote: 2020-04-03 04:51pm D
SpottedKitty wrote: 2020-04-01 03:25pm
chimericoncogene wrote: 2020-04-01 03:54am I really can't imagine people building such a Bernal Sphere-sized room to build factories, suburban houses, apartment blocks, and office towers full of cubicles in it, although those might line the walls or go through canyons in the floor or something, but objections to this apartment-dweller's point of view are welcome.
IIRC (been a while and the book's in a storage box somewhere) the cylinder designs in High Frontier used the end caps for housing, industry, etc. and heavy industry that could be adapted to zero-g in non-rotating pressurised volumes outside the end caps. Has anyone looked back at those ideas to see which ones still look workable (and, more importantly, live-in-able).
It depends on the design. Most people associate Gerrard O'Neil with just a couple of space station designs; the Bernal sphere (aka Island One), the classic cylinder (aka Island Three), and if they know anything about his involvement they will know he contributed to the Stanford Torus (even though it isn't in his book). But even at the article chimericoncogene linked to there are a bunch of his lesser known designs. For example, there is the Sunflower station design (which I was already aware of) which has sort of a pill shape and works like an inversion of the Bernal sphere. The middle of the pill is all window and everyone lives exclusively in the end caps (it gets its name from the appearance of its mirror system). Then there is the Crystal Palace design which appears to be a concession to Stanford's obsession with toroids: the human living area is a bunch of shielded rings inside a cylinder and agriculture is done in a cylinder with smaller radius, hence giving it a top hat look from the side. Stanford really thought humans couldn't tolerate as many RPMs as O'Neil believed we could, but in truth the science is still out on that (the experiments all suffer from being done in Earth gravity, apparently). Finally there is the Model One cylinder, which looks at first glance like the Island Three cylinder, except it hybridizes the ideas of that station with ideas from the Sunflower and the Crystal Palace. Humans inhabit only the end caps which are heavily shielded against cosmic rays (the mirror system is correspondingly more elaborate than Island Three); meanwhile the three sectioned middle part of the cylinder is purely for agriculture. Finally, there is a sphere hanging off the back end that could be for industry or a radiation shelter, or whatever else you might want that doesn't need natural lighting. From a distance the best way to tell apart an Island Three from a Model One is the extra mirrors of the Model One that reflect light into the end caps.

And of course there are plenty of other designs that people have come up with over the years that build off of O'Neil, MIT and Stanford's ideas. In fact, there is a yearly [urlhttps://space.nss.org/settlement/nasa/Contest/]student contest[/url] by the National Space Society that used to be hosted by Nasa until 2018. One of my favorite designs to come out of it is the ASTEN design which is a beaded/banded cylinder meant for Earth orbit. The beads are for human habitation and work, the bands are for parks, and the center of the station is where industry is conducted in microgravity. But what's most interesting for this thread's purposes is the 2020 winner, as those students looked at the feasibility of colonizing the Kuiper belt with cylinder type stations (which they named the Stern habitat). Interestingly, even though their station is intended to orbit as far out as Neptune or Pluto, they still opted for natural sunlight, reasoning that a massive and complex parabolic mirror system is still more efficient than turning light into electricity and then back into light. The inefficiencies exist both at the level of the solar panel and the LEDs supplying the light, and they wanted farms to have as much solar energy as possible in order to grow food. They don't explain why they didn't consider using nuclear power, though. Perhaps its because of the specific Kuiper belt object they proposed for this station to orbit near (486958 Arrokoth). Nuclear material isn't evenly distributed in the solar system, so they may be under the assumption that they cannot rely on it so far out in space. Sunlight might get less intense out in the Kuiper Belt, but its still present and usable with a sufficiently large parabolic mirror. As for heat buildup in the mirror system, they have some interesting ideas about using benzine or other liquids with a refractivity similar to glass as a coolant to spread the heat around the entire system rather than allowing it to build up in any one place and cause damage.
https://space.nss.org/settlement/nasa/C ... /ASTEN.pdf

The ASTEN design is indeed very logical. It uses the big spaces for parks while putting all the apartments and industry in modular, relocatable, replaceable pods (the entire settlement can thus easily be upgraded, expanded, and repurposed over the decades, and built up piecemeal like a normal city - you can relocate the industry to the suburbs and replace it with bars and hotels and stuff when you get rich).

I had something similar in mind with my Bernal-Sphere-Park, but I put the apartment blocks in the walls of the park, on the basis that apartments won't need as much upgrading and apartments with a nice balcony and a view of the park would sell much better. I live in a dense city, and a view of an open space, any open space, is a massive relief even if it's surrounded by tall buildings. The same might be said of giving the modular habs (presumably for the less well-off) windows into the central hub. People don't particularly like living in holes without windows. Economics alone would drive placement of homes overlooking the park sections, and mansions and a few open-air markets in the parks.

Huh. I would have assumed 0.5g to be reasonably safe for habitation, but talking about babies and children - yeah, not unless that apartment is at a steep steep discount. The first eight weeks of pregnancy are when the fetus is most sensitive to the environment, so you can't even relocate the lucky couple in time (what if the woman works in the zero-gee section?!). IVF all the way. Need to look up ISS embryo experiments to be sure.

Ahh... it uses LEDs for artificial sky. Much more flexibility in hab design.

https://space.nss.org/settlement/nasa/C ... abitat.pdf

The Stern Cylinder... not as good a design, IMO. No point putting industry or agriculture in the same hab as residential. Different requirements, different challenges. They seem pretty confident that you can do basically anything with enough mirrors, but a diagram or something to illustrate would have been nice.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by Formless »

chimericoncogene wrote: 2020-04-03 11:33pm
https://space.nss.org/settlement/nasa/C ... /ASTEN.pdf

The ASTEN design is indeed very logical. It uses the big spaces for parks while putting all the apartments and industry in modular, relocatable, replaceable pods (the entire settlement can thus easily be upgraded, expanded, and repurposed over the decades, and built up piecemeal like a normal city - you can relocate the industry to the suburbs and replace it with bars and hotels and stuff when you get rich).

I had something similar in mind with my Bernal-Sphere-Park, but I put the apartment blocks in the walls of the park, on the basis that apartments won't need as much upgrading and apartments with a nice balcony and a view of the park would sell much better. I live in a dense city, and a view of an open space, any open space, is a massive relief even if it's surrounded by tall buildings. The same might be said of giving the modular habs (presumably for the less well-off) windows into the central hub. People don't particularly like living in holes without windows. Economics alone would drive placement of homes overlooking the park sections, and mansions and a few open-air markets in the parks.
To me the ASTEN makes a lot of sense as a colony for Earth orbit (or at least orbit in Earth's vicinity). The argument for using natural lighting in the Stern design doesn't necessarily matter for a beaded station like ASTEN, because sunlight is so plentiful you can eat the inefficiency of converting light into electricity and back again and not care so much. Meanwhile, solar flares and solar radiation mean radiation protection is that much more important. You might still want some way of getting natural sunlight into the bands for parks and recreation, however. There are ways you can do that, like putting mirrors inside the cylinder, as opposed to O'Neil designs that put the collector mirrors on the outside. This makes sense because O'Neil's designs are pressurized throughout the entire structure, whereas a banded cylinder is only pressurized in the individual modules. As long as it doesn't get in the way of the central industrial facility (which it shouldn't), then its a trivial modification to make to the ASTEN design.

Another reason the ASTEN makes sense in this regard is that it doesn't necessarily need to produce its own food as long as its in Earth orbit. The designer puts consideration towards hydroponic farming aboard ASTEN, but there is a limit on what can be grown there and no specific statements are made towards where in the habitat this would be done (unlike O'Neil's many cylinder designs). People can easily tire of eating spinach all the time. However, in Earth orbit you can presumably have other stations specialized for farming import food for the colonists of ASTEN and other stations. Even O'Neil's Island Three designs included that as a possible solution, since you need to pair up two counter rotating cylinders anyway for stability reasons, you might decide to have one cylinder devoted to farmland and the other to cityscape (as opposed to going with farming modules like you usually see on the Island Three design). Some of the NASA artwork shows off this idea of dedicated farming habitats. Said habitats also become tourist destinations for industrial and white collar workers in the more "utilitarian" beaded cylinders like ASTEN.

Ultimately, its a design with a lot of merits as a very utilitarian approach to space colonization. The electric lighting, hydroponics, and relatively small amount of space dedicated to natural landscapes are all signs of that. But it won't work in all contexts. That's why a variety of colony designs are worth considering, depending on where in the solar system you intend to put it. Some designs will work in multiple parts of the solar system (like the Sunflower design), some work best close to home, and some parts of the solar system create unique challenges that require specialized station designs to make it work.
Huh. I would have assumed 0.5g to be reasonably safe for habitation, but talking about babies and children - yeah, not unless that apartment is at a steep steep discount. The first eight weeks of pregnancy are when the fetus is most sensitive to the environment, so you can't even relocate the lucky couple in time (what if the woman works in the zero-gee section?!). IVF all the way. Need to look up ISS embryo experiments to be sure.

Ahh... it uses LEDs for artificial sky. Much more flexibility in hab design.
Yeah, and the worst part is that the problems don't end after the child is born. The rest of the child's development has to then happen in less than Earth's gravity, unless you are in a station simulating a full one G by spinning. And without children, it can't really be called a colony, just a station.
https://space.nss.org/settlement/nasa/C ... abitat.pdf

The Stern Cylinder... not as good a design, IMO. No point putting industry or agriculture in the same hab as residential. Different requirements, different challenges. They seem pretty confident that you can do basically anything with enough mirrors, but a diagram or something to illustrate would have been nice.
No, as long as the habitat is pressurized like O'Neil's designs you can put whatever you want in there. You just designate floor space for one purpose or another, just like we do on Earth. Plus, if you read closely they say they would make the interior landscape look hilly in order to hide the station's curvature and thus make it seem more naturalistic; but to save mass and make maximum use of floor space, those hills would actually be hollow and artificial so that you can put things "under" the hills. You can put anything from manufacturing to office space in them, and have residential or agricultural space in the valleys or sides of the hills. Also, the proposal specifically states that the Stern station would have four cylinders in total (with pairs of cylinders attached to one another by their light diffraction tubes). Like O'Neil's designs, you can divide up the roles of each cylinder so that one is more focused on industry and one is more focused on farming.

As for how the mirror system would work, the Tango III designs that won the 1996 competition show how its done. Take particular notice of the Tango III solution for a ring/toridal habitat in particular. Even though its a solution meant for a ring station, it could be adapted to getting light into the rear cylinders as well. You just need to fiddle around with the angles and geometry a bit and it works.

By the way, back on to your original post, a lot of those light paths may look suspicious, but it appears that they actually do work out once you realize that you aren't necessarily dealing with parabolic mirrors like you might expect. People can be a bit loose with their words and forget what a parabolic mirror actually is. Parabolic mirrors actually focus light onto a single point, which actually isn't what you want unless you are using a thermal-electric power station. Spherical mirrors can bounce light at steep enough angles that, for instance, make the sunflower station design make a lot more sense. The "sunflower" mirror system isn't parabolic, the front cap of the pill gets its light from the most central portion of the mirror array while the rear cap gets it from the mirror's outer edges. So the geometry works out better than it looks at first glance. Again, a similar solution can be used in the Stern design to get light into the rearward cylinders as well, especially since the Stern design uses a translucent tube to help diffuse light throughout the station, among other functions mentioned by the authors. Whether this solution is as functional as the Tango III solution is up for debate, and likely comes down to what trade-offs you want to make with regards to heat management VS mass penalty. But then, in the outer system you are already dealing with either massive mirror systems or powerful nuclear reactors to supply electric lighting sufficient to grow crops with. And you might find that some crops just don't thrive under electric lighting. Biology has to be taken into account as much as anything else, much like in the discussion of microgravity and the problems it creates for child development.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

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Oh, and by the way, a lot is said about the use of mirrors to direct light, but prisms, lenses and refraction is another method of redirecting light rays when the the geometry just doesn't quite work out. So called prism lighting was well known when Gerrard O'Neil was writing The High Frontier, but at some point it started going out of fashion with archetects in response to innovations in electric lighting and the use of florescent light in particular. However it has never been completely forgotten about, since prism sheets can be used to create anidolic lighting effects that appear to even out the lighting in a room, even when there is no more light in the room than there was before. It has to do with the psychology of human perception, as the eye responds to light in a non-linear fashion, and it would definitely help solve the problem of uneven lighting in stations like the MIT class design you reposted in the OP. Indeed, I imagine many of these designs took inspiration from anidolic lighting techniques right from the start, but that goes unnoticed by people unfamiliar with the technology.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

Formless wrote: 2020-04-04 05:47am Oh, and by the way, a lot is said about the use of mirrors to direct light, but prisms, lenses and refraction is another method of redirecting light rays when the the geometry just doesn't quite work out. So called prism lighting was well known when Gerrard O'Neil was writing The High Frontier, but at some point it started going out of fashion with archetects in response to innovations in electric lighting and the use of florescent light in particular. However it has never been completely forgotten about, since prism sheets can be used to create anidolic lighting effects that appear to even out the lighting in a room, even when there is no more light in the room than there was before. It has to do with the psychology of human perception, as the eye responds to light in a non-linear fashion, and it would definitely help solve the problem of uneven lighting in stations like the MIT class design you reposted in the OP. Indeed, I imagine many of these designs took inspiration from anidolic lighting techniques right from the start, but that goes unnoticed by people unfamiliar with the technology.
Thanks for the heads-up on the technology. It seems a habitat can have a lot of fun with mirrors, prisms, and other thingamabobs. I always thought the Sunflower and Model One were using two frustrum-shaped mirrors instead of a spherical mirror - but I think I can see how it would work in the Outer System, with a much much bigger mirror array (I always thought another solution might have involved a big ring mirror coaxial with the habitat but with a much greater circumference - good for Island Three-style cylinders stranded out in the Kuiper, without the hassle of mirrors under tension).

As for the Stern Cylinder... I was more concerned about its relatively (vs. ASTEN) limited upgrade-ability. If you're building a town, a community to last a few hundred years, you're going to want to be able to adjust the layout, swap out modules, build new factories, accommodate new fads and industries, etc. By putting everything under one roof, in one rotating building filled with load-bearing walls you can't tear down (the paper has multiple cylinders coming out like a segmented centipede if expansion is necessary, IIRC), it might limit your options somewhat. I can understand the case for not making large rooms modular (e.g. the park and attached bits), but the other stuff... why not?.

The corollary is probably that the modular approach has other problems. Modules may be less durable than a unitary structure, and leak more. Radiation shielding will have to be offset more and a special gantry built for replacement of modules the size of a skyscraper (or even a small town). Renovating (as in somehow trying to turn an industrial district into a street full of pubs because the population grew and the city center grew with it) might be cheaper than wholesale replacement. Maybe mass transit will be so good physical distance won't matter. Living in a city with the best mass transit on the planet... I can think of examples both for and against - mass transit tends to help smaller satellite cities compete with the center, and there's a lot of incentive to build nice stuff in the outskirts since everyone can easily go to the shiny new mall on the outskirts - but at the same time, everyone wants to go to the traditional town center, and the town center gets packed packed packed on weekends. But I'm no city planner either.

Tradeoffs are probably highly contextual, but it's always fun to speculate.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

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chimericoncogene wrote:Thanks for the heads-up on the technology. It seems a habitat can have a lot of fun with mirrors, prisms, and other thingamabobs. I always thought the Sunflower and Model One were using two frustrum-shaped mirrors instead of a spherical mirror - but I think I can see how it would work in the Outer System, with a much much bigger mirror array (I always thought another solution might have involved a big ring mirror coaxial with the habitat but with a much greater circumference - good for Island Three-style cylinders stranded out in the Kuiper, without the hassle of mirrors under tension).
Actually, the Island Three and Model One's three large mirrors are actually not a single large mirror like people think, they are a platform for thousands of smaller mirrors on automated arms so that the direction of sunlight can be controlled more than the setup initially appears to allow. That's how the night/day cycle is simulated on an Island Three. Plus, while the technology wasn't developed enough during the time The High Frontier was written, it would also allow you to put photovoltaic solar panels among the mirrors as well to generate electricity. O'Neil instead placed a thermoelectric power plant on the nose of the cylinder, which can be seen on the Model One sketches and Sunflower design, but is often omitted from artwork of the Island One. Hence, in Gundam (the most notable pop culture depiction of O'Neil cylinders) they use the nose as a spaceport instead. With photovoltaics, that actually makes sense. Also, you can add six more panels not normally seen on traditional Island Three sketches coming off the habitable areas of the cylinder with PV panels, again something O'Neil didn't do. Of course, there are some depictions in science fiction of Island Three stations with a full mirrored cone shining light onto the entire surface of cylinder, but its not standard.
As for the Stern Cylinder... I was more concerned about its relatively (vs. ASTEN) limited upgrade-ability. If you're building a town, a community to last a few hundred years, you're going to want to be able to adjust the layout, swap out modules, build new factories, accommodate new fads and industries, etc. By putting everything under one roof, in one rotating building filled with load-bearing walls you can't tear down (the paper has multiple cylinders coming out like a segmented centipede if expansion is necessary, IIRC), it might limit your options somewhat. I can understand the case for not making large rooms modular (e.g. the park and attached bits), but the other stuff... why not?.
Because enlarging the cylinder isn't the only way to expand? Just build another station, there is plenty of room in space. Of course an outer solar system station needs more space to begin with due to the enlarged mirrors, but no big deal, I don't think the mirrors are going to be the width of the moon or anything. Each station is a town in itself, sure, but then a collection of towns becomes a county. Again, every pair of cylinders is already paired with another pair of counter rotating cylinders, so that's kind of already how it works.

As for modularity inside the station, you just treat the interior like a plot of land and voila, its de-facto modular. If you need to build a new factory, you find a plot of "land" in the station and build it there. There is a reason O'Neil's stations and the Stanford torus are usually depicted as having traditional buildings inside of them-- they are large enough you don't need specialized modules. In fact, in a way its the ASTEN that's harder to upgrade because of its separation of facilities into modules that are then connected directly to the structural elements of the station. The central hub isn't just a manufacturing facility, its also the place all of your structural cables are attached to. If you need to upgrade the industrial hub, you need to find a way of doing it without taking appart the entire station. And even the habitation pods pose an issue, because swapping them out while the station is spinning would be quite a difficult task, and possibly create stability issues. Not to mention that even if it can be done, over time the docking technology attaching the pods to the hallways may go obsolete. In contrast, the pressurized walls of a traditional cylinder, sphere or toroid are unlikely to go obsolete any time soon. They will need maintenance due to microimpacts and radiation, however, but that's true of all space stations.

Finally, even if you go with a beaded habitat, you might decide to add a cylindrical wall surrounding the modules anyway in order to add more radiation shielding. This goes double in a wartime construction where the station has to worry about becoming collateral damage, or worse, deliberately attacked. The difference of course is that this wall won't have to be airtight, you can just pour concrete into a mold in space and call it good. The Crystal Palace design takes this approach, only with toroids rather than modules.

Really, there are other advantages of this approach, like the relatively small volume of air you need to fill the habitat with, much like ring stations. Of course, a cylindrical station can lessen its air needs as well by adding an inner cylinder that is exposed to vacuum, thus turning the station into a torus stretched vertically. Anything with a ceiling needs less air, really. But Gerrard O'Neil loved haing gliding so ceilings represented lost potential to him. Another advantage is that in the short term, its an easier design to approach and sell to people. The construction goes in multiple well defined stages, and even in the beginning before you ever have to spin it up the industrial section can be put to work. It combines well with inflatable habitat technology and habitat modules that other spacecraft designs call for, so building one seems like a logical extension of other technologies that people want to experiment with. So its a good design for relatively near term colonization, or again, a station you might see in Earth orbit because it is useful in the early stages of colonization development when the logistics and infrastructure for space colonization is still in its early stages. But it likely won't see as many upgrades over time as other station designs, because while it is modular, its likely that early choices in how it will be used will dictate its use for a long time afterward.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

Formless wrote: 2020-04-04 11:04pm snip
Good points as usual, Formless. With this sort of thing, a lot of the speculation is going to be context-dependent as usual.

I remember the Island Three tilting mirrors, but was always under the impression that it was a design option rather than a necessity (I think someone said the drawbridge-thingy mirror wouldn’t work, although I don’t understand the argument). It was a headscratcher for me – if you make the mirrors complicated and heavier, and spin them at five gees at the end of a mirror petal, you might be in some trouble when you need to maintain them. Doable but inelegant. The mess leads me to greatly prefer the nonspinning conical configuration made famous in the Rosinante trilogy. Nonspinning configurable smart mirror with motorized panels, or even a dumb mirror with the base end less “filled-in”. No night and day though, but that might actually be okay in a three-shift colony if you’re just building suburbia.

Image

I live in a densely packed apartment complex - the closest thing to a non-self-sustaining arcology that exists. A hundred thousand people live in the ~100 so twenty-five-storey apartment buildings within a half-kilometer of me. There's a big park, with playgrounds, a library and swimming pool, in the middle of the apartment complex. The whole complex is raised up on a big two-storey podium, with markets, malls, preschools, schools, clinics, 200+ restaurants, parking, a few offices, etc. on the first and second floors, and roads and parking levels on the "ground floor", buried under the mess. Mass transit runs underneath, and you can get to the airport in maybe an hour by mass transit.

I'm biased towards viewing the space colony as an arcology-in-space, or a growing group of arcologies-and-other-buildings-in-space. To my layman's eye, habitats are basically clumps of big spinning buildings floating in the void, drilled out of the lunar mares, or erected on the Callistoan surface. At least in the early stages, they're going to be expensive enough to build that square footage prices will be very high (maybe $1000+ USD a square foot). These economic conditions are similar to Singapore, Hong Kong, and other similar city-states, where sticking 100,000 people in a square kilometer or two and building an exquisite support base for them within walking distance makes economic sense. Then again, I can see reasons why it might not be the case.

You outsource all your food production and industry to separate modules, equally jam-packed, zero-gee or open to vacuum. You don't put oil refineries, factories and farms right next to prime real estate - although you can with light industry - my place had fifteen-storey textiles and food processing factories once... adjacent to living areas. You may want them on separate life support, air filtration, and other systems. They have different requirements. Ditto financial districts. When your city grows, you add extra modules - either along the same rotational axis under the same radiation shield cylinder, or build an entirely new axis and fly in formation with it/nail it to a big open framework you can build maglev lines on.

I assume some plugging-in to a greater system economy.

If you think of individual habitat units as buildings rather than artificial land (reclaimed from the sea or from space), a more modular approach may make more sense. Your arguments are good as usual, but a good case, I think, can be made either way. Dust curtains will help a lot if you need to renovate, and there are good solutions to various problems.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

On review... you're spot on, formless. ASTEN type modularity is clearly excessive for a PMF habitat, unless the rock rats are really impoverished, or the site is specialized.

I was thinking more along the lines of trying to move modules the size of ASTEN's park segments, or even whole spin-units (think crystal palace guts), among a formation of spin units, if it became necessary to say, expand the city center or add a shiny financial district. BTW, i would file Asten is just another crystal palace derivative, but that's just me.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

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chimericoncogene wrote:Good points as usual, Formless. With this sort of thing, a lot of the speculation is going to be context-dependent as usual.

I remember the Island Three tilting mirrors, but was always under the impression that it was a design option rather than a necessity (I think someone said the drawbridge-thingy mirror wouldn’t work, although I don’t understand the argument). It was a headscratcher for me – if you make the mirrors complicated and heavier, and spin them at five gees at the end of a mirror petal, you might be in some trouble when you need to maintain them. Doable but inelegant. The mess leads me to greatly prefer the nonspinning conical configuration made famous in the Rosinante trilogy. Nonspinning configurable smart mirror with motorized panels, or even a dumb mirror with the base end less “filled-in”. No night and day though, but that might actually be okay in a three-shift colony if you’re just building suburbia.
The tilted mirrors don't seem like such a structural problem to me, personally, but if its an issue I would think a ring structure at the ends would help keep them from flying off. We normally see a beaded ring at one end of the Island Three, and it always struck me as odd that it would be proposed for agriculture of all things. You would think that making a ring of pods with a vastly larger diameter than the cylinder would mean the plants are growing in a much higher gravity environment, or else no gravity at all! It just seems odd. But it isn't so odd if its real purpose is to help keep the mirror arrays attached.

As for day/night cycles... look, its a psychological thing. The human brain evolved to expect a day/night cycle, and the human eye literally produces vitamin D (I think?) in response to sunlight. We can't replicate sunlight even with LED's because its too broad spectrum, and much higher intensity. We can only fake it well enough to reset people's biological clocks and cause insomnia. Now, from what I have heard about people living above the arctic circle, permanent nighttime has worse health effects and psychological effects than the permanent daylight that happens during summer, but both require not insignificant adjustment for people living in those parts of the world. Even at my latitude summer has an effect on my sleep because night is just too short (especially with access to artificial lighting...). That's why so many colony designs not only try to use natural sunlight but also try to simulate the day/night cycle. Its not really that hard, but the Rosinante design seems to preclude it. Perhaps its not a bad idea to make maximum use of sunlight to keep the station warm as you go farther away from the sun, but unless it has independently moving small mirrors inside the cone it will have issues with simulating day/night, and thus create issues for the colonists. Also, it will weigh significantly more than a three to six mirror array system, because of course it will. If you aren't in the outer solar system (distance of Uranus or farther), I think its worth keeping the mirror system as light as possible when taking advantage of natural light.
I live in a densely packed apartment complex - the closest thing to a non-self-sustaining arcology that exists. A hundred thousand people live in the ~100 so twenty-five-storey apartment buildings within a half-kilometer of me. There's a big park, with playgrounds, a library and swimming pool, in the middle of the apartment complex. The whole complex is raised up on a big two-storey podium, with markets, malls, preschools, schools, clinics, 200+ restaurants, parking, a few offices, etc. on the first and second floors, and roads and parking levels on the "ground floor", buried under the mess. Mass transit runs underneath, and you can get to the airport in maybe an hour by mass transit.

I'm biased towards viewing the space colony as an arcology-in-space, or a growing group of arcologies-and-other-buildings-in-space. To my layman's eye, habitats are basically clumps of big spinning buildings floating in the void, drilled out of the lunar mares, or erected on the Callistoan surface. At least in the early stages, they're going to be expensive enough to build that square footage prices will be very high (maybe $1000+ USD a square foot). These economic conditions are similar to Singapore, Hong Kong, and other similar city-states, where sticking 100,000 people in a square kilometer or two and building an exquisite support base for them within walking distance makes economic sense. Then again, I can see reasons why it might not be the case.
*shrug* I live in the US suburbia. I've literally seen suburban urban sprawl happen within my lifetime turn farmland into housing developments right before my eye. My town was never a rural one, but it would surprise you how close the two environments can get in some parts of the US. That has an effect on your perspective on urban life. The farmland was right next to us, and the city a short drive away. We were at a perfect midpoint, right up until the suburbs engulfed everything in a surreal turn of events. Now we have to drive to see the farms. Living in the city has sociological and psychological effects that may not be desirable to everyone. Not to get too topical but right the number of COVID-19 cases in my state is only doubling every five days last time I checked. In New York on the other hand the virus is spreading at least twice as quickly and already killed far more people in that one city than my entire state. Why? Because of population density. People are far closer to one another, and compared to cities like Tokyo and Hong Kong, New York is just the tip of the iceberg. When materials are plentiful in space, there may be no perceived need to jam people into colony stations at nearly that same level of urban density. Certainly that was not the assumption of Gerrard O'Neil, whose artwork almost always depicts suburban life inside the colonies, reflecting North American ideals at the time of writing. But there isn't necessarily anything wrong with going that rout, so long as you have the resources to make a sufficient number of space stations.

Of course you are right that in the immediate future, colonies will have to be built on the assumption that fewer resources are available because of a logistical and industrial bottleneck, and as I said that is when beaded cylinders like the ASTEN appear more attractive. But once you overcome that hurdle then the only reason I can see to jam so many people into a small space is if you really just want to maximize population sizes in general, and then you have to start dealing with the fact that air is not free.

Personally, I don't subscribe to the proclamation pulled out of Ken Burnside's ass that colonies only last three generations before dying out (history seems to suggest otherwise), but if you can't keep up with population growth then you will have a problem. Its a historical fact. You can only jam so many people into a crowded space before people decide to spread out. As a once nomadic species, we have an instinctive need for breathing room.
You outsource all your food production and industry to separate modules, equally jam-packed, zero-gee or open to vacuum. You don't put oil refineries, factories and farms right next to prime real estate - although you can with light industry - my place had fifteen-storey textiles and food processing factories once... adjacent to living areas. You may want them on separate life support, air filtration, and other systems. They have different requirements. Ditto financial districts. When your city grows, you add extra modules - either along the same rotational axis under the same radiation shield cylinder, or build an entirely new axis and fly in formation with it/nail it to a big open framework you can build maglev lines on.
Fossil fuels like oil and coal only exist on Earth-- the reason why is in the name. So that activity isn't going to contribute to poor air quality in space. Most of a colony's energy is either going to be solar or nuclear, unless we can figure out hydrogen fuel cells in which case that takes the place of oil. We might also eventually figure out fusion power (we're already closer to it than I ever expected we would be in my lifetime!), but you could argue that was already covered under "nuclear". Likewise, I think if you look into it, most manufacturing can be cleaned up, and in fact most first world industry is relatively clean thanks to environmental legislation. The issue is that capitalism has driven us towards globalization for the most vile of reasons-- third world countries don't have the laws on the books or the will to enforce them to ensure industry is done in a clean way, because giving a fuck about the environment takes money, just like paying your workers a fair wage. However, once you are sealed up in a can with that manufacturing, you aren't left with much of a choice. Either way, the station's life support systems absolutely has to clean the air regardless of where in the station that pollution is coming from. In the end, you have no choice but to recycle air, because you are living in a closed system. Air that goes into the module for processing smelly fish will end up in the module full of houses one way or another, and the best you can do is scrub and filter it. Or if you live in a large enough habitat, you can actually have a weather system form which will help mitigate issues-- and it will form, all on its own, in a sufficiently large hab.

Of course the Earth itself is also a closed system, as we are learning the hard way, but I'm getting off topic.

Of course the classic O'Neil cylinder is sectioned off into three livable segments, so if you feel like industry really has to go somewhere separate from housing and finance (which, really, has no reason to be separated from one another-- many office jobs can be done at home, and like schooling its largely culture that tells us that these kinds of workspaces should be separate from the home) you can put that into one strip, and then put farming on the third strip. Or you can even modify O'Neil's design by having five strips (without going to a banded cylinder design the mirrors dictate an odd number of strips. That's why O'Neil didn't just go with two strips-- the mirrors would point at eachother rather than the actual living space!). But still, no matter how you divide it up in planning, treating the floorspace/land area as general purpose leaves the colonists with the flexibility to change things as the colony evolves. Planning can only get you so far, there will be eventualities that require the colonists to create novel adaptations in order to survive or thrive for generations.
I assume some plugging-in to a greater system economy.

If you think of individual habitat units as buildings rather than artificial land (reclaimed from the sea or from space), a more modular approach may make more sense. Your arguments are good as usual, but a good case, I think, can be made either way. Dust curtains will help a lot if you need to renovate, and there are good solutions to various problems.
Again, floorspace is inherently modular, but modules ironically are not. Modules are purpose built, more akin to parts of a spacecraft than general purpose rooms in an office building that you need merely redecorate. You have to go in and physically disassemble parts of said spacecraft in order to change the infrastructure of it, and the same would go for a module-based beaded station that's designed like one big building. Plus you have to do those renovations while people are trying to live in it... its a nightmare. Its less like repurposing a room and more like redoing the plumbing... and the wiring... and the network... and literally everything else as well. Again, removing the entire pod could create stability problems because of the amount of mass being taken off and replaced, all while the station keeps spinning. Once installed, that pod should only be removed if absolutely necessary.

Compared to that, just tearing down a building and replacing it with another, something humans have done since antiquity, seems much easier. Plus you don't have to deal with the psychological problems of feeling like you are indoors all the time. There is a reason that even the ASTEN's designer made sure to have park spaces, and why O'Neil envisioned growing forests in his stations. From my perspective as someone who has always had a park within walking distance and national forests within driving distance, I really don't understand how city slickers cope with a lack of nature in their lives. Perhaps the secret to why New Yorkers (stereotypically) act like assholes is that they really are insane. :-P
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chimericoncogene
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

Formless wrote: 2020-04-05 06:01am
chimericoncogene wrote:Good points as usual, Formless. With this sort of thing, a lot of the speculation is going to be context-dependent as usual.
Nonspinning configurable smart mirror with motorized panels, or even a dumb mirror with the base end less “filled-in”. No night and day though, but that might actually be okay in a three-shift colony if you’re just building suburbia.
The tilted mirrors don't seem like such a structural problem to me, personally, but if its an issue I would think a ring structure at the ends would help keep them from flying off. We normally see a beaded ring at one end of the Island Three, and it always struck me as odd that it would be proposed for agriculture of all things. You would think that making a ring of pods with a vastly larger diameter than the cylinder would mean the plants are growing in a much higher gravity environment, or else no gravity at all! It just seems odd. But it isn't so odd if its real purpose is to help keep the mirror arrays attached.
Its not really that hard, but the Rosinante design seems to preclude it. Perhaps its not a bad idea to make maximum use of sunlight to keep the station warm as you go farther away from the sun, but unless it has independently moving small mirrors inside the cone it will have issues with simulating day/night, and thus create issues for the colonists. Also, it will weigh significantly more than a three to six mirror array system, because of course it will. If you aren't in the outer solar system (distance of Uranus or farther), I think its worth keeping the mirror system as light as possible when taking advantage of natural light.
My phrasing was unclear, but the Rosinante-type mirror is a smart mirror with thousands of independently motorized units, identical to the louvered system used on Island Three but non-rotating. Since it can have the same overall mirror area as Island Three, just over a bigger, non-rotating and hence maybe lighter support structure, I suspect it might end up lighter overall. As to whether adequate light dispersion can be achieved without "checkerboarding" the habitat if you fill in the basal end less, I think mirrors can be shaped (convex?) to spread the light a little - easier to do in microgravity.

The big ring on the end of Island Three is non-rotating, IIRC, and hosts lots of little spinning crystal-palace-type agricultural habs with high-CO2 environments. At least, that is the traditional description. The ray diagram is below.

Image
When materials are plentiful in space, there may be no perceived need to jam people into colony stations at nearly that same level of urban density. Certainly that was not the assumption of Gerrard O'Neil, whose artwork almost always depicts suburban life inside the colonies, reflecting North American ideals at the time of writing. But there isn't necessarily anything wrong with going that rout, so long as you have the resources to make a sufficient number of space stations.

But once you overcome that hurdle then the only reason I can see to jam so many people into a small space is if you really just want to maximize population sizes in general, and then you have to start dealing with the fact that air is not free.

Its a historical fact. You can only jam so many people into a crowded space before people decide to spread out. As a once nomadic species, we have an instinctive need for breathing room.
Eh. Some people like the city center, some people like the countryside. Why else are housing prices in city centers so high? Some people want to be close to where the action is. And given the high cost of habitat, and "historical" city centers being small, I suspect that colonies will be jam-packed more often than not (not in the late phases of course).

I tend not to subscribe to the "air is expensive" idea. The life support and recycling system is expensive. But oxygen is literally everywhere (Ceres is icy, and it's got brine with ammonium compounds on the surface, and the moon is drowning in oxidized compounds), nitrogen should be uber-cheap in the Kuiper (or anywhere outside the snow line - antifreeze in the moons, remember), and you barely need millions of tonnes of the stuff (O2, N2, etc) to fill in an Island Three. My guess is that Island Three weighs billions of metric tonnes. Worry about shipping in enough industrial base to build Island Three before you start worrying about the air (which is way under 1% of total mass).
However, once you are sealed up in a can with that manufacturing, you aren't left with much of a choice. Either way, the station's life support systems absolutely has to clean the air regardless of where in the station that pollution is coming from. In the end, you have no choice but to recycle air, because you are living in a closed system. Air that goes into the module for processing smelly fish will end up in the module full of houses one way or another, and the best you can do is scrub and filter it. Or if you live in a large enough habitat, you can actually have a weather system form which will help mitigate issues-- and it will form, all on its own, in a sufficiently large hab.

Of course the classic O'Neil cylinder is sectioned off into three livable segments, so if you feel like industry really has to go somewhere separate from housing and finance (which, really, has no reason to be separated from one another-- many office jobs can be done at home, and like schooling its largely culture that tells us that these kinds of workspaces should be separate from the home) you can put that into one strip, and then put farming on the third strip. Or you can even modify O'Neil's design by having five strips (without going to a banded cylinder design the mirrors dictate an odd number of strips. That's why O'Neil didn't just go with two strips-- the mirrors would point at eachother rather than the actual living space!). But still, no matter how you divide it up in planning, treating the floorspace/land area as general purpose leaves the colonists with the flexibility to change things as the colony evolves. Planning can only get you so far, there will be eventualities that require the colonists to create novel adaptations in order to survive or thrive for generations.
There will most definitely be hydrocarbon processing in space. Carbonaceous chondrites and all the rocks beyond the snowline are covered in and partially made of tar, IIRC. You probably won't be burning the hydrocarbons outside rocket engines, but I am virtually certain there will be a petrochemical/chemical industry of some sort because people need plastics, pharmaceuticals, lubricants, carbon nanotubes, etc, etc. That stays outside.

And regarding smells - heavy industry - and even light industries handling malodourous compounds will have to have their own basic life support circuits. It's not like Earth, where the atmosphere can dilute everything to relative harmlessness. It should not be particularly hard to duplicate the basics - since you've got a bigger life support circuit backing you up, you just import O2 and export scrubbed CO2 as needed. If you've ever stood outside a mall's ventilators at dinnertime - oh dear god the smell - you will appreciate the need for this. Smells will have to somehow be handled. People can live with most anything, but it would kill your property values. Since you've spent so much money building a park-like Bernal sphere instead of packing everyone into little boxes in a Crystal Palace, you'll want your money's worth of park. A few positive-pressure systems should sweep the smells well into the ass-ends of the station.
Again, floorspace is inherently modular, but modules ironically are not. Modules are purpose built, more akin to parts of a spacecraft than general purpose rooms in an office building that you need merely redecorate. You have to go in and physically disassemble parts of said spacecraft in order to change the infrastructure of it, and the same would go for a module-based beaded station that's designed like one big building. Plus you have to do those renovations while people are trying to live in it... its a nightmare. Its less like repurposing a room and more like redoing the plumbing... and the wiring... and the network... and literally everything else as well. Again, removing the entire pod could create stability problems because of the amount of mass being taken off and replaced, all while the station keeps spinning. Once installed, that pod should only be removed if absolutely necessary.

Compared to that, just tearing down a building and replacing it with another, something humans have done since antiquity, seems much easier. Plus you don't have to deal with the psychological problems of feeling like you are indoors all the time. There is a reason that even the ASTEN's designer made sure to have park spaces, and why O'Neil envisioned growing forests in his stations. From my perspective as someone who has always had a park within walking distance and national forests within driving distance, I really don't understand how city slickers cope with a lack of nature in their lives. Perhaps the secret to why New Yorkers (stereotypically) act like assholes is that they really are insane. :-P
Fair points. I love the countryside myself, and my place is fortunately a mere fifteen-minute drive from a forested hillside. Hikes are great.

I actually think the only reason the PMF space colony might need anything bigger than a crystal palace would be to put in a nice park, zoo, and swimming pool/rec area for the inhabitants (or if some wealthy people have money to burn on parkview property or hang-gliding arenas). Otherwise, the crystal palace design seems cheap and cost-effective. Instead of taking out a hundred-year mortgage and building an Island Three excessive to our city's needs, why not add an extra crystal palace on the outskirts of town?! You can take a tram instead of a shuttlecraft!

The stability issue is important, and no, unless you are really, really good with maintanence tori. Module swapping (e.g. of all the guts of a crystal palace) is not going to be easy or simple. You'll probably have to eminent domain the whole hab, inert and de-spin, build a huge scaffold to drag the old hab out, and then pack the new hab in. Then spin up and de-bug the new module and trash/relocate/refurbish the old crystal palace. The stability issues are going to be with the base-frame the whole complex is built on.

I have no idea whether something like a New York-sized Solar Power Satellite studded with concrete cylinders filled with crystal palaces, each 500-1000 meters in diameter, can be made stable. There will be huge stability issues if, say, the new university (in the center of town! One transit stop from Government Wheel and Bernal Sphere Park!) they're putting in is a lot heavier than the old apartments they're pulling out, but that's an exercise for the urban planner of the future.

Sticking new cylinders on the end of old ones always seemed to me harder than building a space frame and then attaching new cylinders on the side, but I'm a layman and that's just me. Stability issues will exist with both approaches, and I think an argument can be made for needing some way to remove cylinders "stuck in the middle" too.

But maybe location will be a lot less important in the future like you say, and everyone will formation-fly instead, and drop shuttles will be as safe and reliable as mass transit. In which case an orbital ballet to slot the new cultural center in will be equally dicey.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by chimericoncogene »

:D Regarding cultural differences, Formless, my first thought back when I first laid my eyes on a Bernal sphere illustration was "Suburbs? Seriously? What a waste of space. You could fit a hundred thousand people in there easy.". :lol:

To each his own, as usual.

Although I can see trade offs where packing a habitat would end up being more expensive even in the short-medium term. Some people will still like crowds.
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Re: Colonies in Space: Mirrors vs Artificial Lighting

Post by Formless »

chimericoncogene wrote:My phrasing was unclear, but the Rosinante-type mirror is a smart mirror with thousands of independently motorized units, identical to the louvered system used on Island Three but non-rotating. Since it can have the same overall mirror area as Island Three, just over a bigger, non-rotating and hence maybe lighter support structure, I suspect it might end up lighter overall.
Your suspicions don't add up to me. Like, literally, have you done the math? Gerrard O'Neill was an engineer, and designed these things with an eye towards materials strengths and mass, and given that his smaller designs do in fact have mirror arrays that wrap around the entire structure, I would expect that the Island 3 and Model One use three mobile structures rather than a single static one for good reason. If the structure is an array of independently moving mirrors, then the structure gets heavier due to the required machinery for independent tracking. That's the trade-off for using independent tracking.

Plus you have to consider the effects of micro-meteor impacts over time on the structure. A lighter structure is also more fragile. So you could make a mirror array that is as light as a solar sail, but it will be easily punctured and torn. That means it isn't a practical method for lightening the structure. Meanwhile

Also, the Rosinante design would call for the mirrors to move far more than the O'Neill design in order to keep light going into the habitat rather than on the opaique walls of the cylinder, especially given the RPMs the cylinder makes. That would seem like a lot more wasted energy and call for a higher maintenance cost overall than a set of three mirrors would (or any other subset of rotating mirror arrays).
As to whether adequate light dispersion can be achieved without "checkerboarding" the habitat if you fill in the basal end less, I think mirrors can be shaped (convex?) to spread the light a little - easier to do in microgravity.
Checkerboarding is a non-issue due to diffraction. The distance between the individual mirrors in the array and the colonists mean that the light will naturally spread out over a distance and make it all appear like one mirror rather than thousands of individual mirrors. So no checkerboarding will be apparent to the human eye.

Plus, you can take the window sections and replace them with a smaller width lens instead, allowing you to upscale the size of the land strips while keeping the same amount of light coming in. The mirrors would have to focus the light onto a smaller area which in turn gets spread out again by the lens. The spread would further mask the appearance of checkerboarding. On the other hand, I don't know how feasible it is to do this once you consider the need to cool the lenses.
Eh. Some people like the city center, some people like the countryside. Why else are housing prices in city centers so high? Some people want to be close to where the action is. And given the high cost of habitat, and "historical" city centers being small, I suspect that colonies will be jam-packed more often than not (not in the late phases of course).
HA! Ha ha. Hahahahahahahahahaha. :lol: That isn't how the real estate market works at all, dude. If you look at the actual economic status or income levels of people living in inner cities, you quickly find that rent prices can actually be a predictor of poverty, as counter-intuitive as it sounds. No, at least in the US the rich don't live in the inner city. They get as far as fucking possible from it as they can, as often as they can, while balancing that against the need to visit the city for business reasons.

There is an entire sub-field of sociology called Urban sociology that deals with this kind of thing. If you go back in time to the Medieval period, the rich and poor actually lived pretty close together in cities. Cities were structured around other things, like types of profession practiced in any given quarter, and the need for military defensiveness. However, there are two constants in city planning. First is the presence of a city center where trade and business are done. The other is that the richest and most powerful members of society often have multiple homes while the poor and middle class can afford only one. The rich didn't mind having homes close to the middle and lower classes in these cities because they wouldn't spend all year there anyway. Often, their real home was a manor, estate, or villa far away from the city (or even an actual castle depending on the time period) that was remote and rural. These enclaves of the rich persist into the present day, as does the pattern of rich people having a second home in the city for business reasons. We call these enclaves "exurbs," to indicate that they are even farther away from the city center than a suburb, and every major city in the modern day has them if you know how to look for them. If you are in the United States, you can look at census data to find out how rich a given area is (the geographic data is organized by zip code, which you can then reference back to a map). The exurbs are often surprisingly far from major city centers and can be immediately identified by a very high average income. Double check these exurbs against Google Maps, and you find that they look rich. Even if there aren't actual mansions among them, they are always clean, well kept, full of nature, big houses, big lots, lots of trees and other cultivated natural landscaping, and often when the people are visible you find they are white as slate (something census data will also tell you). I've driven through a few of them. I can't imagine how someone can afford to have a lake in their back yard, and yet that's a thing I have actually seen. And this isn't even the richest of the rich. You can't even get close to the mansions of the super rich. They won't let you.

So if the rich are actually averse to the inner city, why are housing prices so high? It has to do with economic activity and exploitation. Back to the topic of city structure, when the Americas were settled by the British, the cities took on a specific socioeconomic structure that is still somewhat visible in old cities like Boston and New York, and the patterns are reflected all over the country in different ways. The basic pattern looks like a bullseye. In the middle you still have the marketplace and place of business just like in European cities, and if there is any housing its often where the rich stay while on business. Think of Trump's "apartment" in the Trump Tower that literally has as much floor space as a mansion. But as soon as you move away from the city center, the next ring of the bullseye is full of the destitute, the poorest people in the city. As you go away from the city center, the people living there get progressively better and better off economically. Unlike in Europe, the colonists tended to self segregate along economic lines. The middle class didn't want to live next door to the poor, the poor didn't want to live near the outright homeless, and the rich didn't want to live near any of them (hence plantations in the old days and exurbs in the modern era). But everyone middle class and lower still needed jobs, and those jobs were concentrated in the city center. Now if you were destitute or poor, your only way of getting to your job was to walk, and the chances were your employer had little tolerance for lateness. So being close to your job was essential. Middle class residents could afford other forms of transportation, though, so they could afford to live farther out. Alternatively, some of the upper middle class actually did business out in the country side with the true upper class, so living at the edge of the city made sense. It also allowed you easier access to parks, recreation, and nature, so overall it was more desirable.

Fast forward to today and the same trends remain. A few innovations happened: industrial and transportation hubs appeared that few people want to live around, cars happened, and modern cities will have multiple specialized city centers rather than just one. But there is still one "main" city center often identified as "downtown" or the Inner City and is visually distinct because of the presence of skyscrapers. That's what most people are talking about when they think of the city, but that's not the whole city, and the vast majority of people don't live downtown. Poverty often clusters around the areas just outside of downtown or at the edge of downtown, as well as in industrial zones (though redlining and ghettos can't be forgotten in this discussion either). The middle class tends to gravitate to the suburbs because cars enable such sprawl; you can easily get to the city center for work and education, or away from the city for recreation. Plus there is less of a smog issue. Suburbs also tend to have parks, but in some cities the car also enables day trips outside the sprawl entirely to nature reserves (national parks and the like). Poor people also have cars, but the cost of maintenance encourages the use of public transportation, which is another reason why the city centers still have clusters of poverty around them. If your car breaks down, you have a backup plan that keeps you employed. But lastly, lets talk about rent.

Just because a house or apartment has a high price doesn't mean the people living in it are rich or even middle class. It means the land owner, who often lives in a fancy suburb or even an exurb, can charge a huge amount of rent from whoever does live there. This is where the issue of economic exploitation rears its ugly head. Whenever you hear about people living from paycheck to paycheck, keep in mind that those people don't necessarily have shitty salaries. What matters is the costs of living. Some cities are famously expensive to live in for various reasons-- be it the price of goods or the price of rent and utilities, a person's economic status is relative not only to their income but also their expenses. A really expensive city like San Fransisco might have poor people making surprisingly high income, yet they are still poor because everything costs so much. And the price of living can have a knock on effect where you might think the solution is to move out of town to some place more affordable, but many people get trapped because they lack the ability to save up the money needed to move. You have to somehow save up money while paying for your basic needs, and not everyone living in the inner city can do both. So while some people might live in the inner city by choice, that's not everyone. It may not even be the majority of people. Some people might live there because that's where their family has always lived, and they never think to move even if it would have mental health benefits.

So when you look at the housing prices for major city centers, or even the average income, keep in mind that those numbers have to be put in context. The average income has to be put into perspective of rent prices and other cost of living expenses, as well as the presense of outliers (i.e. the super wealthy assholes who spend half the year or more in a summer home far away from the city). The price of land in the inner city is a natural byproduct of being nearer to commerce. It also reflects patterns of economic exploitation such as white flight, redlining, and gentrification. This shit is complicated, and you can't simplify the high prices of housing in inner cities to demand alone.

Meanwhile, while we don't fully understand the connection between access to natural environments and good mental health, we know the correlation exists. So why, then, is it desirable to have our space habitats emulate the unhealthy environment of the inner city-- to literally pack people into little boxes, as you cutely put it-- when its not that hard or much more expensive to instead emulate the more naturalistic environment of the suburb? You know that's what habitats of the rich are going to look like anyway. :-P
I tend not to subscribe to the "air is expensive" idea. The life support and recycling system is expensive. But oxygen is literally everywhere (Ceres is icy, and it's got brine with ammonium compounds on the surface, and the moon is drowning in oxidized compounds), nitrogen should be uber-cheap in the Kuiper (or anywhere outside the snow line - antifreeze in the moons, remember), and you barely need millions of tonnes of the stuff (O2, N2, etc) to fill in an Island Three. My guess is that Island Three weighs billions of metric tonnes. Worry about shipping in enough industrial base to build Island Three before you start worrying about the air (which is way under 1% of total mass).
I said its not free, not that its expensive. You still have to move it from place to place in the solar system, which isn't free. Oxidized compounds aren't the same thing as oxygen, you first have to chemically change them to be breathable atmosphere, and that isn't free. And once a habitat has filled its atmosphere to capacity, it needs to balance that atmosphere constantly with some sort of recycling system (like, say, actual plants recycling the CO2). You have to remember that it isn't free in the sense that you have to balance the production of CO2 and other unwanted gasses because you don't want to cause ecological problems in miniature, because you don't have the support systems of an entire planet to fall back on. Its for that reason that a space colony would likely do well to consider controls on industrial activity and possibly even population cap (well, it has to cap the population at some point anyway because of the limited room inside the ship). That's what I mean.
And regarding smells - heavy industry - and even light industries handling malodourous compounds will have to have their own basic life support circuits. It's not like Earth, where the atmosphere can dilute everything to relative harmlessness. It should not be particularly hard to duplicate the basics - since you've got a bigger life support circuit backing you up, you just import O2 and export scrubbed CO2 as needed.
You just admitted yourself that life support isn't cheap. Why add to the costs during the construction phase when proper economic planning can limit the problem to begin with? Why, for instance, should we be treating plastic as a disposable resource? Tell me one good thing that has come about because of that short-sighted attitude towards petrochemicals.
Sticking new cylinders on the end of old ones always seemed to me harder than building a space frame and then attaching new cylinders on the side, but I'm a layman and that's just me. Stability issues will exist with both approaches, and I think an argument can be made for needing some way to remove cylinders "stuck in the middle" too.
I'm not an expert, but wouldn't your approach cause problems with the habitat tumbling if you screw up the balance of rotating forces? I think your approach is generally better applied to large diameter toroid stations like the Stanford design than cylinders. In fact, expanding a Torus by attaching additional toroids is the classic way of enlarging such a colony, with limits.

I think the solution isn't to physically connect more than two cylinders at any one time, but simply to have them orbit within close enough distance to each other (whether in the Earth-Moon system or in the Earth-Sun Lagrange points) that if you need to visit your grandma on the Old Town habitat, you can just take a ride to the spaceport and fly out to meet her. It also satisfies the desire to have space travel play a role in your science fiction, too.
:D Regarding cultural differences, Formless, my first thought back when I first laid my eyes on a Bernal sphere illustration was "Suburbs? Seriously? What a waste of space. You could fit a hundred thousand people in there easy.". :lol:
You know, the funny thing is that O'Neil proposed that with some speculative advances in materials technology the Island III design could be scaled up to allow millions of people to live in one, perhaps hundreds of millions. Which would require quite a packed cityscape no matter how you design it. There is a reason he envisioned colonies as an opportunity to experiment in new forms of governance, we're talking literal nation states in space here. Zeon from Mobile Suit Gundam is right out of his playbook.
"Still, I would love to see human beings, and their constituent organ systems, trivialized and commercialized to the same extent as damn iPods and other crappy consumer products. It would be absolutely horrific, yet so wonderful." — Shroom Man 777
"To Err is Human; to Arrr is Pirate." — Skallagrim
“I would suggest "Schmuckulating", which is what Futurists do and, by extension, what they are." — Commenter "Rayneau"
The Magic Eight Ball Conspiracy.
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