Launching a Torus Station

A torus space station is one of the staples of future thinking. Launching it in one piece from the ground is not. It has however, been occasionally mentioned in various comments. Here are a few numbers on the idea a few of us have kicked around from time to time.

Assume a 100 meter torus with a 10 meter minor diameter. 23,000 net cubic meters of internal volume should do for a start. A 50 meter radius that is not enough for an Earth gravity at under 4 rpm is sufficient for lower levels of artificial gravity that may mitigate some of microgravities’ harmful effects. It is getting it up there that seems to be a bit of a problem.

10,000 square meters of station surface would mass 540 tons if we assume the skin has the equivalent mass of 2 centimeters of aluminum including insulation, braces and such. Internal structure and furnishings would have to go up in subsequent flights. 540 tons in orbit would require something over 10,000 tons GLOW. This is heavy launcher country. Fortunately the internal volume of the torus is sufficient for fuel tanks.

Bladder fuel tanks inside the station could mass under half a percent of fuel mass, while LOX could be carried with simple bulkheads in the appropriate sections. Sooner or later an F1 equivalent will become operational at reasonable prices. 15 of them could push the torus edge on with a sled take off to avoid building launch towers and such. This would be a near SSTO with just engines dropped off for recovery at designated velocities when they are no longer required. Final push to LEO could be with just one engine with all the others recovered from various suborbital velocities.

How the station would be equipped and used would be up to the parties that paid for it.

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johnhare

johnhare

I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.
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30 Responses to Launching a Torus Station

  1. Andrew_W says:

    Why?

    Wouldn’t lifting it in sections with assembly in orbit make more sense?

  2. ken anthony says:

    The simplest, taking a page from RobotGuy, would be to use six 4 port airlock legos (120 degree separation) with six BA-330. Six FH launches later you have a 36 crew station in LEO for a total cost of $1.2b completed in about a year (but usable with the first module.) This gives you 12 free docking ports which also provide for simple expansion. Compare that to the I.S.S.

  3. johnhare john hare says:

    It would depend on your viewpoint. Orbital assembly and EVA work is such a bogeyman to some that this would make good sense. Launching curved torus sections would be entertaining to say the least. If it could all be modeled and tested with smaller units, it might well make sense to send it up in one go, provided there were a market for it.

    I think one of the failed opportunities is all the Shuttle external tanks that expended. Fifty of them in a rotating chain would have provided gravity and workspace to spare.

  4. George Turner says:

    I’ve had a few other thoughts on getting a torus up.

    A) What if you launch the floor separate from the ceiling and walls? A structurally rigid floor would be like an open ended can or wedding band at launch, depending on the floor width to ring diameter ratio. The goal is to make it like a thin, low drag wing section in flight, perhaps propelled by Falcon 9H fly-back boosters and expendable upper stage boosters. In that concept, the booster are arranged in a circle for launch and go up like a mass rocket volley, by they are connected together by the thin ring, as if they were all flying wingtip to wingtip. In this concept, the floor is necessarily a dry stage because it doesn’t have significant internal volume.

    Obviously the thinner section is going to be far less radially stiff than a full-up torus, so the boosters would have to avoid putting undue loads on the structure. As it goes supersonic I imagine the ring might act somewhat like a normal shock inlet (where “normal” is the technical term for the type of shock inlet on an F-16), but I’m not sure what effect that would have. Perhaps max-Q will be really exciting. You might also add a few similarly thin spokes to aid the rigidity and also serve as passages from the axis down to the ring so you don’t have to add those in orbit.

    Once spun up, you have a rigid partial-gravity floor where you could inflate Bigelow tents, exactly as they are displayed now at Bigelow’s factory. Or suppose the ring was actually a floor and a ceiling squashed together for launch, with inflatable fabric in between. You just inflate it in orbit, separating the ceiling from the floor, and get one continuous tent with an aluminum floor and an aluminum ceiling, with the living space already compartmented into sections and rooms with fabric walls.

    B) What you launched a roll of aluminum sheet (much like it comes from the foundry) already threaded into a solar-powered, three-roller bending/shaping machine that turns the roll of aluminum into a big, corrugated floor? Better, use two rolls, one corrugated circumferentially and one corrugated axially (so they corrugations are perpendicular to each other) with the two sheets then spot welded together as they meet up at the exit of the roll formers.

    This concept builds a floor while drastically reducing launch volume, but doesn’t save any launch mass. That creates a problem, because whereas the torus created a huge amount of distributed area for attaching boosters, this scheme would require those boosters to come together in a big wad to launch a giant roll of aluminum, and it adds a lot of complexity because instead of mating completed sections, you have to mate up rolls of aluminum and seam weld them before continuing with construction. And when it completes all you’ve got is a bare floor without any accessories at all.

    But if you scale the concept back to a minimal size and go back to a true torus instead of a floor, 3 meters minor diameter (10 feet) and staying with your 100 meter major diameter, you get a surface area of 2,961 square meters, and with a 6-mm skin (8 to 1 safety factor for 1 atmosphere pressure with 6061-T6), the skin mass is 48 metric tonnes and can be launched by a single Falcon 9H. Stiffeners would obviously be 3-meter diameter rings which would fit inside almost any current launch shroud. Another launch for the rolling machine and welders – and hey, we’re back to complicated in-orbit manufacturing and assembly that’s building a never-ending walkway. But at least it’s not a lot of launches and no spacewalks.

    C) Instead of a ring, launch a thin disk, like a Frisbee or an Aerobie. Spun up, a disk would give you a wider range of G-levels, but you’d definitely want horizontal launch. You could also stay with the inflatable concept described in A, but in this case two opposite walls would be aluminum and others would be fabric. The floors could fold down from the aluminum walls and lock in place.

    D) Launch the torus in sections – as a pair of bananas that form the leading edge of a delta-shaped vehicle that would look similar to many SSTO concepts. Boosters would be attached to the flat sections (the top and bottom if the vehicle was flying back), and the center section between the bananas would also contain a central core that flies all the way to orbit to become a spoke. The area between the bananas could also have room for some throwaway sections, and it might look similar to some bimese concepts.

    Once in space, the bottom of the central core mates with the station’s existing central hub section, forming a spoke, and then the two leading edges fold at the nose (a simple hinge), down and out to form part of the semi-circular torus section. The torus sections (the bananas) could be wet or dry stages, depending on the size of the core and external boosters relative to the payload mass. If the leading edges automatically mate and lock together with the previous torus sections, no spacewalks would be required to complete construction.

    If there were cables installed between the bottom of each leading edge and the bottom of the center core, they could serve as winches and structural load-bearing members, so you could even spin up the station with only two mated sections to form a dumbbell or partial torus, obviously saving the cost of all the sections that weren’t launched.

  5. DougSpace says:

    ECHO 2 was 66 kg and was 30 m in diameter. If you scale this up then a (or the first) Falcon Heavy could put up a simulated Kalpana One of approximately one km diameter / wide. Print it appropriately and the world could witness what looks fairly much like the real thing (albeit a 2-D landscape). Counter spin up a 1 kg flywheel to 60,000* RPMs and you could spin Kalpana to its nominal 1 RPM. I believe that, by over stretching, ECHO 2 rigidized itself which may be necessary given that there is a lot more debris up there than during ECHO2’s days. ECHO 2 lasted 5.5 years before orbital decay. If launched to an equatorial orbit thereby missing the Southern Atlantic Anomaly then the radiation exposure would be much reduced compared to the ISS (perhaps requiring no shielding to be below 20 mSv/yr)**.

    * http://www.extremetech.com/extreme/154405-volvo-hybrid-drive-60000-rpm-flywheel-25-boost-to-mpg

    ** http://space.alglobus.net/papers/RadiationPaper2014.pdf

  6. Stellvia says:

    I envisioned something like Magna Parva’s COPMA system (http://www.magnaparva.com/newsblog/4587313510) to extrude large linked hoops on-orbit, which would then form the outer-rim scaffolding for the construction of the habitat ring from multiple inflatable modules. Monolithic elements like the despin hub may require a BFR launch, but the remainder could be launched in sections on FH-R.

    Image here: http://www.rocketeers.co.uk/node/1164

  7. Paul451 says:

    John Hare,
    Re: Torus.

    I think the aerodynamics of that open centre would be… interesting. You might want to fill the centre with yet more fuel tanks (and an aerodynamic cover.)

    “I think one of the failed opportunities is all the Shuttle external tanks that expended.”

    Everyone wanted to play Lego with shuttle parts, from Shuttle-C to ET-stations, to Jupiter/etc, to not-the-Shuttle-C cargo variants, to Constellation, and now to SLS.

    But you only need to look at Constellation and SLS to see how it turns out in reality. The shuttle was so close to the edge of being impossible, every system was cut to its absolute structural limits, tuned only to the Shuttle stack. Changing any one part meant changing the whole system. Want to replace the solids with four liquids? The change in thrust patterns and associated stresses means you’d have to change so many things on the ET and orbiters you’d basically be redesigning the whole system from scratch.

    Want to get the ET to orbit? Sure there’s often enough fuel left, if you want to burn the stupidly complex and fragile SSMEs to a hard out. Which you don’t. And you probably need an extra booster motor on the base of the tank to circularise its orbit, but you can’t because the tank doesn’t have the strength to carry thrust at that point. That means you have to strengthen the bottom of the ET, which changes the loads on the rest of the ET, so you’ll have to redesign the whole thing; which probably changes the mass and balance, which changes the stresses on rest of the stack, so you’d basically be redesigning the whole system from scratch.

    And the standard ET insulation wouldn’t survive in vacuum. So you need new insulation. But that means redesigning the ET, which means a change in mass/balance, which changes the loading on everything else, which means you’d basically be redesigning…

    There are rocket components which can be “Legoed”. The Saturn 1’s original components were such animals. The Saturn V seemed pretty robust. The Delta IV and Atlas V have a bunch of configurations. Energia was very adaptable. And Falcon 9 is ridiculously flexible, given that it’s been a launcher, a Grasshopper, had legs attached, nearly landed, and is destined soon eventually to become a triple core.

    But the Shuttle system was not one of those systems.

    The Shuttle MkII might have been, if done right. But of course no-one wanted a Shuttle MkII, they wanted an SSTO, like VentureStar. Another beyond-the-bleeding-edge, insanely complex, ultra-fragile system that required a hundred major new technologies to be invented just to be possible, let alone practical. Because they’d “learned their lesson” from the Shuttle. {sigh}

  8. Paul451 says:

    DougSpace,
    “ECHO 2 was 66 kg and was 30 m in diameter. If you scale this up then a (or the first) Falcon Heavy could put up a simulated Kalpana One of approximately one km diameter / wide.”

    For what purpose? Without half a million tonnes of air, you aren’t using it for anything but decoration.

    [There are uses for non-HSF inflatables, but what you describe just seems to be a stunt. And if you’re going to do that, you may as well design it as a 1km long cylinder and paint it like a Red Bull can.]

  9. Grant says:

    What do you mean by “sled takeoff” of 15 launchers?

  10. Andrew_W says:

    Using your figures of 100 meters and 10 meters diameters, how about a system using a 10 meter diameter launch core (some figures for the MCT have this diameter core) with that core being the normal straight cylinder but sliced at 10 meter intervals at an angle of 6 degrees, so with a rocket core with a total length of 100 meters you have 10 stubby sections, once in orbit alternate sections are separated and rotated 180 degrees around the cores longitudinal axis, the result is a third of the wheel, with a 12 degree change in direction between each successive section, a total of 30 sections (three launches) to complete the whole wheel.

    The change of angle at the connection between sections needn’t be any more obvious from inside the station than the fact that airliner hulls are cylindrical is from inside a 777, in both cases the hull is lined with floor, ceiling and walls to make it comfortable for people.

    I’m afraid the idea of launching a 100 meter diameter wheel, already assembled, is too far out there for me.

  11. johnhare johnhare says:

    Out of town. Will reply to several good comments Monday or so.

  12. Paul451 says:

    Andrew_W,
    All you’d have in orbit is the unassembled pieces for a non-air-tight shell. That’s not really the hard part.

    At that point, you might as well be launching “flat packed” panels and frame-elements as a simple conventional payload on a non-crazycustomised off-the-shelf commercial launcher. Orbital assembly will be essentially the same. Ie, better to launch cheap (for space) generic mass-produced elements on a standard, reusable F9 or FH, rather than create a bespoke launcher-station-monstrosityhybrid and still have to hand-assemble the resulting parts. [Aside: Use end-of-life F9/FH cores and if they work, it’s a cheap launch that no-one else wants, and you use them again, and again. When they finally go asplode, all you’ve lost is a payload of cheap elements that you are mass-producing. You merely run the lines another month.]

    John’s point (and the whole wet-lab approach) is that you are launching an airtight structure with much of the basic infrastructure (hard-points, wiring, plumbing, etc) already installed and ready to attach end-use components. But John’s idea has the same disadvantage of having crazy customised single-use hardware, with the added complexity of being completely bonkers unreasonably large.

    Much simpler to…

    …Have Bigelow develop an inflatable wheel in, say, three or four pieces. Launch (deflated) on a standard FH. Dragon-2-style docking systems to let the pieces self-assemble. Assemble while still deflated, thus more compact and rigid, then simultaneously inflate the 3-4 modules to complete the wheel. Bigelow handles the fit-out and hands it off to clients.

    Or…

    …Launch six-to-ten slightly customised BA-330’s, two at a time, on FH’s. Assemble them in a ring, run four to six cables around the ring through loops on the modules, so when spun the modules are sitting on a “bridge” of cables, as if they were sitting on the factory floor at Bigelow HQ. Add a node module or four as a hub, and Bigelow’s proposed truss structures as arms, with inflatable tunnels built in.

    Or…

  13. Paul451 says:

    …Two Bigelow inflatable modules, one large, maxing out the FH capacity. One smaller. Alternatively, SpaceX builds you the shells for two hard modules starting with two different length tanks from their LOx tank manufacturing system, which are then fitted out on the ground (think Skylab.)

    Whichever option you choose, a multi-cable deployment spool is attached to the smaller module, with a docking system to mate it with the larger module once in orbit. The two tanks are fitted out up to 50 tonnes each. The larger tank is fitted for combined HSF hab and plant/animal research lab, the smaller tank as a remote-tended plant/animal research lab. Each is launched on a Falcon Heavy.

    On orbit, they are docked, spun up, and the cable is fed out to create a counterweight/barbell type station. The heavy cable deployment spool ends up on the same side as the bigger module. The station is thus horribly lopsided, with the larger module in close at 1/6th g, and the smaller module way out at 1/3rd g.

    On a transporter (or two or three) running along the cables, you’d have a robot arm, which also serves as a berthing system for visiting capsules when it’s at the CoM/CoS. Otherwise, the two modules would be run as if they were completely independent stations, with separate power/ECLSS/comms/etc. The Mars lab would only be occasionally tended by researchers in visiting capsules, or by staff from the Lunar lab awkwardly EVAing over using the robot-arm transporter system. Otherwise, it would be uninhabited.

    [Of course, whatever the cost/complexity of a station, how it’s designed, how it’s launched, the biggest issue is eliminating 99% of the ground support cost. Unfortunately, that hasn’t been a research priority for ISS’s first fifteen years, and doesn’t look like becoming one before the station reaches EoL.]

  14. George Turner says:

    As an aside, a ground-launched rotating station would probably be a hollow cylinder, like an open ended can with people living in the shell. It’s generally assumed that there would be spokes to go up to the central zero-G axis where visiting spacecraft would of course have to dock, but I would argue that docking at the central axis adds those unneeded spokes and horribly complicates getting ships to and from the station.

    If the spaceships are winged re-entry vehicles instead of capsules, then they have landing gear (great for landing), and have streamlined shapes to which a docking adapter is generally a grafted-on kluge. Meanwhile, the station is a ring, and launch aerodynamics dictate that the inside of the station was, at least when launched, a smooth surface that could make a fine landing strip.

    Axial docking is problematic because the docking adapters can’t rotate but the space station has to, so you have to use large bearings with vacuum seals that can take some of the bumping and grinding inherent in docking, and do so for years. If the non-rotating docking section is long or wide, the docking forces will create greater torques on the rotating bearing and seals, and of course the mechanical interface between rotating and non-rotating sections has to be electrically driven at all times or the drag is going to try to slowly zero the relative rotational velocities, spinning up the non-rotating axis. For the ships attached with rather fragile docking adapters, the applied forces would eventually be a bad thing, but not nearly as bad as the fact that incoming ships can no longer dock unless they can do donuts trying to get to an adapter, with the added fun of making sure they don’t get smacked by any of the ships that are already docked that are now dancing around the Maypole.

    For an added bit of fun, the rotating section isn’t always perfectly balanced (“Superbowl party in the viewing lounge! Everybody bring snacks!” – and the whole crew moves to one spot). When that happens, the axis of natural rotation isn’t the central axis, but instead moves to a point inches or feet feet from that axis. The crew would notice only a very, very slight sense of motion, less than being on a ship in calm seas, but the bearings to the non-rotating section will notice very much. There are some ingenious mechanical ways to mate two non-aligned shafts, or two shafts that aren’t coaxial, and you’d want to use on of those, increasing complexity further and making moving between the two sections a bit like going between train cars on rough tracks.

    Or you could dispense with that entirely and just have the pilots land on the inner surface, just like they were landing on a runway, something they’ve all done a thousand times long before they ever became an astronaut. To land, fly to the station, move to a point roughly aligned along its axis, give or take 50 feet or so, and then take a vector that will thread it, passing through the empty center of the station. Kill the relative velocity when cutting through the plane of the station, which you could even indicate visually with a hundred or so LEDs on the ring, aimed toward the opposite part of the ring, even with color codes telling you how close you are to the plane.

    Given that you started your approach toward the station’s rotation axis from a position roughly along the axis, once you are in-plane (where you stopped your approach) you should be roughly positioned for a landing, but not necessarily oriented for it. So you need to rotate your ship so the direction of the station’s axis of rotation passes through your ship from wingtip to wingtip. Roll till the ring looks vertical to you, perhaps thought to your left or right, and then yaw till you’re looking at the scrolling surface square on. Pitch is irrelevant.

    The ring you see should be spinning from above to below, going straight down in your field of view, and your nose should be pointing square on to it like you are aimed to go in nose first at what you see in front of you. It the ring is going from bottom to top, you’re set to land going backwards because you’re upside-down, so slow roll a 180. Now thrust downward (in XYZ) at a few FPS and wait till your wheels hit. If things go south for some bizarre reason just go left, right, or up and avoid “ground” contact.

    Since you touch in zero-G, you would normally recoil back up, but that’s why we’ll put electromagnets hanging down near the wheels and make sure the station’s inner surface has some steel in it. The magnets will maintain the force between the ship and the runway so the brakes can “slow” the ship (actually spin it up to match the station), and as it spins up the centripetal forces will build so that it’s just like landing on a runway, and the astronauts will gradually transition from zero-G at contact to whatever the station G is as their ship rolls to a stop. From that point they just taxi using small electric motors.

    All the flight crew has to do next is get out of the way of the spacecraft stacked behind them for landing, which could mean moving to the side of the runway or down ramps or elevators. It might be like an airliner coming into an airport terminal where a boom mates to the craft, or they might taxi into an airlock, or they might go EVA and enter through a hatch. The point is that there are no docking ports, no hour-long approach with lasers measuring everything to the millimeter, no spokes, no hub, no huge bearings, and no anything except wheels and a steel surface. To depart, a ship can accelerate back to zero-G or just fall off the side. There is no precision to any of it beyond what you need to land and park a Cessna. Any good pilot could make that landing by eyeball because instead of inches, his margin of error is ten or twenty meters, just like any airport landing, and after he’s landed, he can tell the passengers they can get up and walk about the cabin.

    It eliminates spokes (hard to launch with the rest of the station); stairs, ladders, or elevators to go up and down the spokes; a sophisticated mechanical solution to off-center station loads (landing on a slightly unlevel runway is so routine we don’t even think about it, so off-center loads don’t have any affect on the runway landings), large rotating vacuum seals, truly massive high-load bearings, a separate docking section, and a whole bunch of other complexities. At bare minimum, all the initial station needs is a hatch somewhere so that astronauts can walk to it in their suits, which for a 100 meter diameter station is going to mean walking a maximum of 157 meters, except that their pilot can just roll on out till he sees the hatch and then tap the brakes, plus steering over to it, making it maybe 5 or 10 meters for the usual landing. Since they won’t be at zero-G on the short walk, the passengers can puke in their suit all they want. It will just make them smell bad.

  15. RobL says:

    I think a Torus is far from optimal for an early space station.
    -We want to experiment with different levels of gravity for health/biology
    -We need majority of volume in a large zero-g or near zero-g hub section for hangers and docking, experimentation, entertainment etc.
    -Toroidal bodies are hard to build/assemble.

    Also I believe there are big problems with motion sickness at such high rpm, my recollection from old sci.space.tech days is that around 0.5 rpm was max comfortable for most subjects. About 2.5m/s² for a 50m major radius toroid.

    String out that structure into a line and spin end over end, and you can 0-1gee at different locations along 200m length, with 100m left over for a much bigger zero g hanger/engineering section on the rotation axis.

    Really easy to grow or expand in parallel to create more area at certain g levels, (unlike torus). Could have expanded Moon, Mars, Ceres and Earth g levels areas.

    Use long hoytether counterweights attached to both ends that can be winched in or out to slow or speed the rotation up and keep the centre of mass at desired axis (and act as catcher/release for other craft momentum transfer).

  16. Hop David says:

    The simplest, taking a page from RobotGuy, would be to use six 4 port airlock legos (120 degree separation) with six BA-330.

    That’s a neat blog I hadn’t seen before. Thanks for the link!

    Robot guy suggests Lego like blocks but in addition to rectangular bricks, also bricks based on the Platonic solids.

    Six octahedra with six tetrahedra make a nice torus:
    http://clowder.net/hop/OctetTorus.png

    I had designed a Lego like toy based on the octahedral and tetrahedral bricks. Unlike Legos, each face has a male/female connector. 8-part or 4-part molds are much more expensive than 2 part molds so I broke the octahedron into 8 triangle panels and the tetrahedron into 4 triangular panels.

    The goal was ease of manufacture but the triangle panels also enable compact packing that make it possible for the structure to fit within a fairing.

    Here’s a pic of my toy:
    http://hop41.deviantart.com/art/Delta-Blocks-106245089

  17. Hop David says:

    The simplest, taking a page from RobotGuy, would be to use six 4 port airlock legos (120 degree separation) with six BA-330.

    That’s a neat blog I hadn’t seen before. Thanks for the link!

    Robot guy suggests Lego like blocks but in addition to rectangular bricks, also bricks based on the Platonic solids.

    Six octahedra with six tetrahedra make a nice torus:
    http://clowder.net/hop/OctetTorus.png

    I had designed a Lego like toy based on the octahedral and tetrahedral bricks. Unlike Legos, each face has a male/female connector. 8-part or 4-part molds are much more expensive than 2 part molds so I broke the octahedron into 8 triangle panels and the tetrahedron into 4 triangular panels.

    The goal was ease of manufacture but the triangle panels also enable compact packing that make it possible for the structure to fit within a fairing.

    Here’s a pic of my toy
    http://hop41.deviantart.com/art/Delta-Blocks-106245089

  18. DougSpace says:

    Paul, Re: One km diameter / wide thin Kalpana One

    > For what purpose?…what you describe just seems to be a stunt

    Yes. A stunt intended to inspire people with a vision of what could be possible. Don’t take my suggestion too seriously. If given a free FH launch, I’d rather aim for sending equipment to the ice at the lunar poles — not a talks stunt.

    > half a million tonnes of air…

    Against a vacuum, the thin Kalpana One would need much less than that.

    > paint it like a Red Bull can

    An advertising stunt which could generate revenue. But beside that, it wouldn’t inspire people to do much other than remain on Earth drinking Red Bull.

  19. Dave Klingler says:

    I’d much rather launch a couple of BA330-sized stations* connected to a hub by cables, around 900 km in diameter, rotating at 1 rpm, in an equatorial orbit a la Al Globus. As a demonstration of what can be done, that gives us a 1G hab with radiation levels that would permit indefinite stays and procreation, i.e., a real space colony.

    Once two habs are connected by cables, there’s not a lot of practical difference between making them 100 meters or 900, at least after the whole thing’s built. The cable’s not the determining factor; rather, it’s the logistics of making one’s way from the hab to the center and back. Once that mechanism’s present, the station might as well be built to a full 1G.*

    Creating such a station as a Mars laboratory continues the implicit assumption that we need to research and demonstrate Mars colonization. Think about it. We could create a 1G, radiation-friendly environment in space with no gravity wells and millions of tons of asteroid material wandering past, waiting to be harvested. Or we could created a small research station to help us figure out how to live in a much more hostile environment, at an impractical distance to allow support or commerce from the Earth. I would posit that the 1G colony near Earth will always be preferable, for any population n where n=1 to 7.3 billion or beyond.

    * Which would allow off-the-shelf manufacturing tools to be brought up, which would allow manufacturing in orbit to begin decades sooner.

    ** I’ve actually developed the impression that BA330s would do okay for this purpose with very few changes.

  20. Paul451 says:

    Dave Klingler,
    “around 900 km in diameter”

    I hope you meant 900m?

    “rotating at 1 rpm”

    This is one of the reasons why we need a variable gravity facility. There’s an assumption that the maximum people can tolerate is 1RPM. But the research is widely heterogeneous, with some studies only picking up bad effects at 3-4RPM, others suggesting some people can build tolerance at up to 6RPM (especially because we’d be able to pick crews specifically for their tolerance of motion sickness, and prior adaptation to zero-g.)

    And it matters. Radius is proportional to the square of rotational period. So for 1g, a 900m 1RPM station could instead be a 56m station at 4RPM, or a 25m module at 6RPM.

    “The cable’s not the determining factor;”

    Actually it is. Keeping the cable(s) from twisting will be a major problem. (You can’t easily use a flywheel to reduce twisting, because it will torque against the main spin axis, making station-keeping more complex.) Longer the cables, bigger the problem. (Hell, this is an issue just with station using a long rigid truss.)

    “in an equatorial orbit”

    Very few Space Settlement plans even suggest a use for their proposed giant space stations. So here’s something…

    A Clarke-style manned GEO “radio tower” space station. You create a common installation in a limited, high-demand GEO slot that allows satellite owners to just plug’n’play their transmission equipment. Essentially you have a facility similar to a radio/TV broadcast tower near a city, where individual vendors lease space and share common infrastructure. You supply the power, propulsion, general pointing, general comms/switching/control, and a stable standardised base. The client only needs to supply the actual broadcast hardware.

    By offering common infrastructure, you should be able to save costs for the client. A manned station means that they can have any outages repaired quickly, allowing systems to be used until they fail, not replaced in anticipation of failure (or because station-keeping propellant ran out). And with regular supply runs, it becomes simple to send up new equipment/spares when needed.

    Because it’s a single site, with no risk of collision between your clients systems, you can cram more “satellites” into a single GEO slot. Very useful in regions where slots are in limited supply, such as high-value markets.

  21. Paul451 says:

    DougSpace,
    “it wouldn’t inspire people”

    I don’t know why space advocates are so convinced that “inspiring people” is the magic ingredient to making big things happened in space. Apollo was the most inspiring thing ever to happen in space and led to the least inspiring follow up. It doesn’t work.

    Money works. If you can create new markets, you expand. If you can’t, you stagnate.

    “> half a million tonnes of air…
    Against a vacuum, the thin Kalpana One would need much less than that.”

    Sure, a few dozen kilograms. But, as I said, you can’t actually do anything with it. It’s just a decoration.

  22. Peterh says:

    Seems to me that a realistic potential to make a profit is all the inspriation needed.

  23. Dave Klingler says:

    Paul451,

    I hope you meant 900m?

    Actually, for the past few days I’ve been thinking, “Did I write radius or diameter?” The answer to the question you asked is, “No, I meant 900m in radius.” I hadn’t realized I’d written km instead of m, as well. Sigh.

    with some studies only picking up bad effects at 3-4RPM…

    Do you have a citation for those studies? I was under the impression from the 1960’s studies cited by O’Neill that even 2 RPM was a bit much.

    Regarding cable twist, that’s also an interesting observation. Again, do you have a citation? I would have thought that a linear arrangement, motorized mounts and pre-twist would take care of that problem.

    Al Globus suggests that a 500-600km equatorial orbit would require no shielding at all to meet an annual 20 mSv threshold. It’s evident that I should have provided more information so that people would get my (and Al Globus’) point without looking up and reading his paper: in that orbit, at 1g gravity, humans can live and reproduce without problems from radiation or diminished gravity. I think we’d do very well to place our next outpost as Al Globus as suggested.

    My point regarding cables was more that once two habs were connected that way, with some sort of trolleys running between them, or between them and a center hub, it doesn’t matter that much whether the cable is short or long, at least from a trolley system point of view. One might as well use long cables and build a 1g station and ask the inhabitants to put up with the longer commute. Perhaps if more habs were added later, a ring cable could be added around the outside circumference with more trolleys.

    While a permanent manned station at geo would be a great thing to have, it only requires a few people to keep things in repair. I think the purpose of John Hare’s post was a very early space settlement, and my post was really to point out a simpler method of getting started.

    Many thanks,
    Dave

  24. Paul451 says:

    “Do you have a citation for those studies? I was under the impression from the 1960’s studies cited by O’Neill that even 2 RPM was a bit much.”

    Best summary article I’ve found: TW Hall There’s even a summary table at the end of section 4.

    The ’60s the results were all over the shop. I suspect there’s a high degree of difference between people, making small studies really susceptible to wild variations in results. Add in the experimental methodology. (Could the person feel motion? Could they see rotation, could they feel variations in the mechanism. How long were they given to adapt? How much distraction were they given during the adaptation period.)

    “Recent studies, however, are showing that, if the terminal velocity is achieved over a series of gradual steps and many body movements are made at each dwell velocity, then full adaptation of head, arm, and leg movements is possible. Rotation rates as high as 7.5-10 rpm are likely feasible.” – – Lackner, James R.; DiZio, Paul A. (2000) Artificial gravity as a countermeasure in long-duration space flight. J Neurosci Res. 2000 Oct 15;62(2):169-76.

    “sensory-motor adaptation to 10 rpm can be achieved relatively easily and quickly if subjects make the same movement repeatedly. This repetition allows the nervous system to gauge how the Coriolis forces generated by movements in a rotating reference frame are deflecting movement paths and endpoints and to institute corrective adaptations.” – Lackner, James R.; DiZio, Paul A. (2003). Adaptation to rotating artificial gravity environments. In, Journal of Vestibular Research (vol. 13, p. 321-330).

    “Regarding cable twist, that’s also an interesting observation. Again, do you have a citation?”

    No. Combination of gut feel, basic angular momentum and the difficulty developers had making even the rigid truss on the ISS (Freedom before it) actually “rigid”.

    As astronauts move around the hab module on a tether/cable, they are putting rotational torque on the module at 90 degrees to the major axis of rotation. That’s going to cause twisting, which is bound to be unhealthy for the tether. A simple counter-rotation reaction-wheel on each module would be spinning on a different axis to both the major spin and the astronaut’s torque, as well as introduce weird torque effects of its own. There will be ways around it, but every novel bespoke system you have to design adds expense/risk/delays and something else to go wrong.

    High RPMs let you build short-radius stations which can be, potentially, single modules. Or two modules hard-linked. Much easier to build. High-RPMs and low-g shortens the radius so much you might only need centrifuges within a non-rotating station. (Which presents its own issues, but solves so, so many others.)

    IMO, knowing the answer to “how much is enough” is worth more than any number of protein-crystal experiments on ISS. It’s worth saying “Okay guys, in 2018, for 12 months we are doing artificial gravity research on ISS. Adjust your projects around it.” (Large centrifuges likely produce vibration, already a bane of micro-g researchers growing their crystals.)

  25. Hop David says:

    Dave Klinger, Paul DiZio’s research seems to indicate humans can grow acclimated to higher RPMs. Here’s one article: http://science1.nasa.gov/science-news/science-at-nasa/2004/23jul_spin/

  26. Paul451 says:

    John Hare,

    Happened to stumble on an image of the original Chrysler SERV resuable SSTO “shuttle”. Conical tanks arrayed around a central payload bay, ringed air-spike engines, 29m/96ft across the base (with 40 turbojet engines for landing!) While staring at it in awe/disbelief (it’s not the first time I’ve seen it, it does that to me every time), it suddenly clicked with your proposal for a single-launch toroidal station wet-lab thing.

    Convert the SERV concept into a slightly easier TSTO pair. Kero-Lox instead of LH/LOx (or at the most, densified Meth-Lox at worst) in two toroidal tanks, one above the other. Two similar vehicles stacked on top of each other, launched vertically. Both run the same engines, just fewer on the second stage. Both stages have the same outer toroidal tanks, the first stage has extra tank(s) in the “payload bay” feeding the extra engines. The second stage has a vaguely aerodynamic shroud on top. Both stages start out expendable but are gradually developed towards reusability, a la SpaceX.

    Mostly you fly it as a regular heavy lift cargo launcher. But occasionally you pull a second-stage off the production line early and add some components to allow you to turn the stage into a wet-lab. Once it’s up there, spin for partial-g. As you launch more wet-lab modules, you join them on the long-axis, creating a cylindrical station. (Although access to different sections will be along a hub-tunnel, it’s a minor inconvenience.)

    It’s nowhere near as wide as you want, but it’s a nice stepping stone. And unlike your proposal, it’s a useful heavy lifter in its own right, letting you amortise your development cost.

  27. johnhare john hare says:

    Everyone,
    Apologies for my lack of response to many excellent comments. Life and work. When schedule sanity returns, I intend to do a new post incorporating the information you have presented. While the 100 meter torus was just an idea piece, I think a financially realistic station with reasonable gee levels could be launched within a few years from go. I was particularly unaware of the possibilities for selected individuals to develop tolerance for considerably higher RPMs than I thought realistic.

  28. Michael says:

    You could launch a simple inflatable rubber torus and then once it is fully inflated in space use vaporised metal techniques to coat the outer torus microns at a time and then when the coating is thick enough use liquid metals to the increase the rate of coating. A second insulation layer could be sprayed on such as polyurethane and then another layer of metal and so on. The rubber torus could then be deflated internally, provided a separating layer is sprayed on first, and removed though a hole in the new structure and used to build another one using the same process. You could then stack all these torus to form a much larger station.

  29. George Turner says:

    The problem with inflating a torus is that turning a bare hull into a working space module, ala the ISS, requires a large labor force, lots of tools, and an enormous number of man hours to install all the tubing, ducting, plumbing, and equipment. The idea of launching a complete torus is that you not only save by building individual modules on the ground, as was done with the ISS, you save by interconnecting them on the ground, too. On the ground your vast work crews can be fed by Pizza Hut and Taco Bell and sleep in houses, instead of depending on incredibly expensive space launch resupply missions.

    But the idea of using an inflatable structure made me think of another idea, when combined with a previous Boondocks post about building a space module out of an entire shroud to maximize internal volume. The shroud concept only suffers from the difficulty of attaching all the externals, and the space assembly concept suffers from all the space walks that can be required for interconnects. The inflatable torus might suffer from being too springy, and in any case would require a huge launcher or number of launchers to approach the thickness and rigidity of a Bigelow module. The all fabric concept likewise suffers the problem of external mounting for a partial G environment.

    So I’m going to combine all those concepts and see if something serendipitous comes out of it. So launch a shroud module, whose outside is necessarily a smooth cylinder along most of its length. Inside it is a special Bigelow football that gets deployed. The football has both ends cut open so they can either expand to a large diameter or squeeze around the perimeter of a shroud module, with a clamping mechanism to make an air-tight seal.

    Running down the length of the Bigelow fabric (along the football’s seams) are pneumatic robot arms, somewhat like a snake version of a Canadarm, which allows the Bigelow module to clamp at one end and move the other end in either direction, like turning a leg-warmer inside out, or somewhat like walking a slinky whose ends pass through each other.

    When the second shroud module arrives, the Bigelow football, one end attached firmly to the first module, is going to stretch out and grab it roughly around the middle, or toward the far end. Then the football is inflated to 4 or so PSI and you have an external work environment so the astronauts don’t have to suit up to work on the exterior of either shroud module. By tensioning the Bigelow football, you could position the two modules to come together as part of a torus instead of a straight spoke section, using it in essence as a giant robot arm.

    Then you bolt the first two shroud modules together and attach all the interconnects and externals, and after that you launch another shroud module, unclamp the Bigelow from the first shroud while keeping it attached to the second, and roll it inside out to grab the third, and repeat until the torus is finished. You could also grab modules that only had a partial shroud (just enough for the Bigelow to attach), such as docking modules or truss sections with a passageway.

    However you couldn’t walk a football around a spoke or a large solar cell that couldn’t retract, so you might need two or three footballs to complete the torus and to maintain it without requiring EVA’s.

    This should allow you to go with the shroud modules to get the largest internal volume supportable by a given rocket family, remove the need for repeated and EVA’s to add external equipment to them, utilize a “soft capture” method for grabbing and positioning new modules (and allowing them to be bolted together with wrenches), and create a structurally rigid torus. It also allows modules to be held together for days or weeks prior to physical attachment, allowing the astronauts time to do any prep work on the end of the old module that had been previously left in a vacuum, as the football grabs around the circumference of a module instead of encompassing it entirely, leaving the far end of a new module unaccessible except by EVA. That could be a plus because that’s where a module’s engine and fuel lines would be, and you might want to empty those before getting into an enclosed space with them.

  30. Paul451 says:

    Best summary article I’ve found: TW Hall There’s even a summary table at the end of section 4.

    Just realised my link didn’t work: http://www.spacefuture.com/archive/artificial_gravity_and_the_architecture_of_orbital_habitats.shtml

    Or http://www.spacefuture.com/archive/artificial_gravity_and_the_architecture_of_orbital_habitats.shtml

    One of those should hopefully work.

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