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Thread: Space habs, and the livin' ain't easy

  1. #61
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    Quote Originally Posted by Van Rijn View Post
    It can be an issue, but that is relatively easy to recycle. Heck, we could do a much better job now if it was economic to do so. Though I wouldn’t be surprised if new colonists would be expected to bring additional locally limited resources with them or pay for them when they arrive, and also pay for the extra resources newly born kids would cost if they add to the population.
    There are several SF stories set in space where you have to buy in to join a space community, and/or only purchase round-trip tickets to stations so the locals don't get a bunch of broke freighter bums hanging around mooching valuable air. See also Babylon 5's Downbelow, a bad neighborhood that collected those too poor to afford passage off the station.
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  2. #62
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    Redundancy is the main reason I am not fond of the classic O'Neill Cylinder design. One big open interior space with windows? Thank you, no. Modular compartments are the way to go. Safety first!
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  3. #63
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    An expandable design might consist of the classic "beaded necklace" / "bow-tie" tethered ring of pods, stacked torii with a common axis, or something similar to O'Neill's but with walls across the endcaps which become interior walls as new length is added to the cylinder and a new endcap built over it. Note that windows would not be practical for any large rotating station; they're just too vulnerable to breakage, leaks, or even getting dirty.

    Once the means of linking rotating and non-rotating station sections gets the kinks worked out of it, it's possible to put several centrifugal drums on a common framework. That way you can have a cluster of habitats with the benefits of closeness and sharing of facilities, with independence of life support and population. It would be more convenient to travel between them; ride elevators and catch a train between hubs rather than to ride an elevator, suit up, board a ferry, go outside the protective cosmic ray shielding, expend propellant, rendezvous with another station, dock, unsuit and ride down to the rim level.

    Shielding may be physical mass or an artificial magnetosphere. Magnetic shields may require superconductors, but that's achievable. Mass does not crap out when the power fails, but it's also inconvenient if you have to move your station's orbit. Using water as a shield provides reserve supplies for many uses. More expensive than regolith, mining tailings or slag, but probably worth it.
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  4. #64
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    Radiation and weightlessness are the main hazards of living in a space station.

    There's been a suggestion that the NASA standards of cumulative radiation exposure during an astronaut's career be limited to 600 milliSieverts. For comparison, a person living at sea level gets 2 or 3 mS per year.

    A lifetime spent in space means monitoring your cumulative radiation exposure at all times. The usual suggested mitigating scheme is heavy shielding of a variety of materials, especially hydrogen-rich substances like water for absorbing solar wind protons, and boron for absorbing neutrons. An extra-shielded "storm cellar" would be a refuge during intense solar activity such as major flares and CMEs.

    The downside the cost of transporting massive amounts of materials in space. If this method is relied on exclusively it would complicate any human space endeavor lasting more than a fairly short period. Any habitat would be a behemoth of mountainous tonnage. If you use water as a shielding material it has to be extracted from an asteroid or comet, transported to the site of construction, and tankage built to contain it.

    Plus, a habitat of that mass would be harder and more expensive to move. In space, nothing is stationary; there will be times when any vessel of any size might need to alter its orbit for station-keeping, if nothing else. Certainly any habitat that expects visitors or deliveries will need to adjust its path from time to time. Small disturbances add up over the long haul. But the more mass, the more delta-V needed to change its course. And in space, delta-V is everything.

    Another idea is to create a mini-magnetosphere out of plasma, redirecting solar wind around it just as Earth's magnetic field does. It should work, but it's untested in the field and will no doubt require much more engineering than the bare description implies (as will every space activity and technology). If it is proven practical, it not only saves mass, it can be used as a magnetic sail to move its vessel (a tiny bit at a time). The con is, one power outage means a blast of cosmic rays in your face. So better keep those wires up to code!

    One thing is certain, no one will be raising children in space until the problem of radiation is addressed successfully.
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  5. #65
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    Quote Originally Posted by Noclevername View Post
    A lifetime spent in space means monitoring your cumulative radiation exposure at all times. The usual suggested mitigating scheme is heavy shielding of a variety of materials, especially hydrogen-rich substances like water for absorbing solar wind protons, and boron for absorbing neutrons. An extra-shielded "storm cellar" would be a refuge during intense solar activity such as major flares and CMEs.
    A qualification - you would want to choose hydrogen rich material where mass is important. If you’re on Mars, the Earth’s Moon, the Martian moons, asteroids, etc. any convenient mass will do for shielding. If you build something like a massive O’Neill style habitat, you’ll want to build it where you don’t need to maneuver it much, and use relatively inexpensive mass transport methods (hence the mass driver that O’Neill promoted).

    I do expect research on electromagnetic and electrostatic radiation shielding will be a major topic once we start getting serious about space development and start having a permanent population above LEO.

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  6. #66
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    Quote Originally Posted by Van Rijn View Post
    A qualification - you would want to choose hydrogen rich material where mass is important. If you’re on Mars, the Earth’s Moon, the Martian moons, asteroids, etc. any convenient mass will do for shielding. If you build something like a massive O’Neill style habitat, you’ll want to build it where you don’t need to maneuver it much, and use relatively inexpensive mass transport methods (hence the mass driver that O’Neill promoted).

    I do expect research on electromagnetic and electrostatic radiation shielding will be a major topic once we start getting serious about space development and start having a permanent population above LEO.
    I think having a nearby (in delta-V terms) body with a surplus of harvestable regolith is convenient. But orbits are dynamic and you can't count on always being near something to scoop your kitty litter off of. Hence the need to go where the action is. Unless you are building your home on or in a body or in a stable orbit around one, you're better off footloose and fancy free paid for.

    Large hard-to-move habitats are a poor idea IMO. People being people, something will go sideways. Be it a misaligned rendezvous maneuver, a bad guy slinging rocks at orbital speeds, a deliberate attack by a military power, or just window glass made by the lowest bidder, if it goes wrong it'll go wrong for everyone in the station at once. I tend to favor the mobility defense, some way to get out of Dodge if the need arises. And several relatively smaller habs make for better redundancy than a big open volume. They need not even necessarily be separate, a frame that holds several spinning "wheels" might be feasible with sufficient engineering of the rotating joints. Certainly you want frictionless and very well sealed points of connection between spinning and stationary sections. But the habs should have the option to be removed in an emergency.

    O'Neill's idea of using the LaGrange points as a place to put a permanent city sized hab seems like a bad idea, though. L4+5 are unstable and you would constantly burn up precious propellant and energy to stay on station. For something with the mass of a small mountain, fuggettaboudit!
    Last edited by Noclevername; 2021-Jul-14 at 03:28 AM. Reason: How do we do it? Volume!
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  7. #67
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    Quote Originally Posted by Noclevername View Post
    O'Neill's idea of using the LaGrange points as a place to put a permanent city sized hab seems like a bad idea, though. L4+5 are unstable and you would constantly burn up precious propellant and energy to stay on station. For something with the mass of a small mountain, fuggettaboudit!
    I think you’re confusing them with L1-L3. Those are inherently unstable, a little like being on the tip of a mountain, but L4 and L5 are a bit like valleys. It takes energy to push an object out. Mind you, a habitat would follow a type of halo orbit around L4 or L5 but wouldn’t need to keep doing corrections to stay there unlike one for L1-L3. Also, they would be around a quarter million miles from both Earth and Moon, not a lot to run into.

    There have been other proposed orbits that might be as good or better, though. If I recall, one would be an Earth orbit about two-thirds the distance to the Moon. Again, not a lot of other stuff in the area and doesn’t require regular adjustment.

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  8. #68
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    Quote Originally Posted by Van Rijn View Post
    Also, they would be around a quarter million miles from both Earth and Moon, not a lot to run into.
    They have all the building materials being delivered, construction machines, personnel, and probably will need regular deliveries of volatiles to make up losses. So there'd have to be considerable traffic around any active space habitat. That means considerable space junk. It can't be isolated if people build a world there.

    I don't know how much dust and debris collects in Earth's Lagrange point, but I know the outer planets' Trojan Points are cluttered with junk.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  9. #69
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    I hasten to add (four hours of haste later) that Van Rijn is right about orbits. Yes, in my sleepy daze I did mix up my L points. Fortunately I am not a space pilot so the consequences are minimal.

    As for the L4 and 5 specifically, if there's a gravitational valley things will fall into it. So both points should have matter in those stable orbits mentioned. I would choose a location closer to the action... which for the foreseeable future means Earth orbit. That's where the infrastructure and people are. Not LEO, but there's plenty of volume between Earth and the outer edge of the Hill Sphere to occupy.

    I think settlements BEO are less likely to begin as planned Colony communities than those in the Earth-Moon system. Anyone who finds themselves in the greater Solar System will be there to work, scientifically or commercially (as a robot repairman?) or even a military base, given the need to justify a space military branch. (I never would have seriously considered that last one a few years ago, but here we are.) Employees of a corporation, government, or other organization with major funding.

    Traditionally towns can grow as workers or soldiers bring their families along to live with them. Even Roman bases (castra) had "camp followers" many of whom included spouses and children of Legion officers. The enlisted often unofficially married locals as well, and settled them nearby. Commerce gathered additional people to service the camp, sell them stuff or provide tailoring, etc. For Medieval forces, camp followers were often the civilian logistics supporting an army, providing or supplementing food for the troops. And famously, few of the miners in the California Gold Rush got rich, but the people who sold them groceries often did.

    That paradigm won't be as practical in space, where every square centimeter of "land" has to be built at a cost and life support comes with hard limits on the population. I propose that vessels with spin-grav habitat modules might provide services; mobile space stations, in other words. Like the classic Amenities Ships of WWII, they'd go to where customers lived, rendezvous, and act as a place for R&R and fresh foodstuffs. A large part of the vessel's habitat might be dedicated to greenhouse operations to give the space workers fruits and vegetables and herbs fresh off the vine. Green spaces might be configured like a pleasant garden or forest for relief from a monotonous life on a mining platform, or what have you. The rest of the amenities ship might be bars and spas. Other recreational methods I'll leave to the imagination.

    There might also be other greenhouse-related services. "Got sewage and CO2 buildup? We can process it for you more cheaply than the outdated, second-rate bioreactors your company/government stuck you with. Tired of eating yeast cultures and bacterial protein? We'll be in dock in sixteen days, bearing a smorgasbord of assorted plant-based foods, simulated meats and fresh air. Dump the smell and eat well with Bluxto Biological Processing. Tell your friends!"

    Such vessels could perhaps be economically viable. They might make a circuit of several crewed orbital facilities if such exist (and if they don't there'll be nothing relevant to this thread to talk about). Relatively small vessels might be considered profitable enough to stay with one particular facility, and if so, then it's likely that families of the customers will try to get aboard to see their loved ones. Now how many of them will actually be able to do so relies on the expense to get there and if things like medical conditions don't hamper the visitors. Getting anywhere in space is difficult and time consuming, you'd be dedicating yourself to a few years at least to spend time with someone. So many of those who go to be near a loved one will effectively be settling there, for extended stays if not for life.

    And that means children might be born in space. Will they be able to grow up healthy? Spin gravity obviates one major problem, but what about radiation exposure? Well, if there's enough humans out there for years to justify Amenities Ships, the conditions for human survival are well established. So the parents might not send their kids back to Earth in all cases.

    When could all this happen? Not soon. Right now the lift is too expensive and the benefits of crews too slim to be sending humans to space in significant numbers; if projects like SpaceX Starship do work out that could change things. But if there are crewed facilities built, I can see R&R and service vessels and family followers to probably become a thing.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  10. #70
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    The human craving for "green space" (no relation) is being increasingly well established. Studies of inner city dwellers show that things like urban gardens and trips to the wilderness provide measurable psychological benefits to kids over those who grow up deprived of those experiences. We evolved surrounded by living things, we might have an innate need for the outdoors for psychological health.

    Now, any human habitat will have to feature green plants of one sort or another for the life support cycle, but a bioreactor full of algae cultures is not going to cut it. It's likely there will be gardens to grow vegetables, but will a hydroponic greenhouse be sufficient for long term habitation? What kinds of environments can we create that will mitigate the problem of artificial, closed spaces? We don't know yet. There needs to be both much more research, and field experience in isolated environments over decades and generations to determine what's really needed and what can be adapted to.

    Mars colonies will probably be built underground or buried under thick mounds of dirt, for radiation reasons. But high altitude plant life can be kept in transparent surface domes so colonists can occasionally spend time up top, admiring the setting Sun. But for spinning space stations there is no horizon, no long distance views. We need to understand how to create the illusion of outdoor areas in a permanent indoors. Sculpted groves of trees, simulated valley floors, blue ceilings with projected clouds, all the ideas need to be tested.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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