Precursor to Station

The comments on the torus station post made it clear that I had skipped steps in suggesting a specific station type. One step is the investigation of exactly how many RPMs are acceptable for a working orbital facility. The acceptable RPMs dictate the length of the station arms to achieve a given gee level. The required arm length or torus diameter needs to be known before design starts, and long before construction starts.

I suggest that an initial investigation on the ground could be a 10 meter radius unit with a 3 meter inclined floor around the circumference. There would be a bit over 190 square meters of available floor area when the unit is spun up. The floor area would be divided into offices, bathrooms, kitchens, bedrooms, and other requirements as needed.

The unit would be spun up to the design RPM for that particular design. There would be one acceptable RPM for any fixed floor angle with several different units for different investigations. This would be terrestrial construction and relatively cheap compared to anything launched which would make multiple units on the ground affordable compared to launching sub-optimal stations.

The unit is spun up to design RPM with the intention that it will spin continually for several months at a time. Several shifts of investigators work in the facility on short and long term ‘missions’. Some works 8 hours plus lunches and go home at night exiting through the hub without stopping the unit. Entry, exit, and transition through the spokes would be part of the experiments. Others stay for 30 days straight, while yet others do business visits of minutes to hours.

The purpose would be to determine whether 10 or more RPM can be adapted to in a working environment. I would see the experimenters as being  perhaps one department of a company or government facility totaling between 20 and 100 people on a near continuous basis plus many visitors. The quality of an individuals work compared to their normal performance in regular environments would be a good baseline to prove/disprove the possibility of very short radius stations for people in high stress and workload environments as during a space mission.

The long term investigators would exit fairly often for family functions and such which would be the  spin equivalent of going to the microgravity sections of the station or an EVA. The ability to conduct the investigation without missing the kids recital or your wedding anniversary would make it possible to get long term volunteers.

After determining the acceptable RPMs for people in a real working environment it wold be much easier to design a real working station. A 5 meter spin radius in orbit is a totally different animal than a 1000 meter radius. If the ability to adapt to high RPMs eliminates 99% of the population, then there would still be about 3 million people in this country to select from plus several times that number world wide.

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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.
johnhare

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17 Responses to Precursor to Station

  1. George Turner says:

    We always focus on the people under partial gravity, but up near the hub people have to deal with zero-G at the same spin rate. So have a crewed Dragon go into a roll at some particular rate and see if the crew can adapt to the spin at near zero-G, even if it takes a day or two. Make that part of an arrival or departure from a regular ISS mission and you can get some of the spin limit data for free.

  2. DougSpace says:

    Off Topic:

    I’d like to suggest that Selenian Boondocks be ready to post a proposal for a humans-to-Ceres settlement program if those white spots turn out to be water. Here’s my case:

    My understanding is that a one-way minimum-energy Homann transfer to Ceres would only take 1.29 years which is less than a Mars flyby mission. If either a lunar base or a Phobos-Deimos (PhD) mission were done then we could have experience with covering an inflatable habitat / greenhouse and delivering supplies and spare parts to sustain crew at the base for extended periods. So, we could slowly send a habitat, cargo, and equipment to Ceres orbit beforehand using ion propulsion so that the crew would have all they need to survive until a window opened for them to return to Earth if they had to. But their goal would be to harvest the ice and so produce their own life support so that they could stay much longer.

    I believe that radiation in transit can be adequately addressed with the proper positioning of crew relative to propellant and provisions to keep them within career limits. Health risk due to micro and hypogravity can be addressed with tethered craft and centrifuges. Breakdowns can be addressed with redundancy, spares, and back-up supplies.

  3. Paul451 says:

    In my last previous post on artificial gravity and rpm/coriolis tolerance, I borked the link:

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

  4. Paul451 says:

    John Hare,
    NASA used to have a smaller version of such a facility, torn down in the 70’s IIRC. I think it’d be useful to build something like that again.

    10m/10rpm produces a full g. At right angles to Earth gravity, that gives you a net 1.4g. But half a g, which gives a combined 1.1g, is still 7rpm. I’d start there, the extra g-load is barely noticeable but you still test high-rpms.

    However, I’d also build a long duration facility which has a much higher g-load (2+ g) and is suitable for 2-3 people. People would come from three groups, an astronaut who is about to go to the ISS, and an astronaut who has returned, and your stay-at-home control. Using pre- or post-loading to test its effects on micro-gravity health issues. Can pre-loading prevent or delay micro-g issues? Can post-loading speed up recovery? How much is required to achieve a given effect.

    DougSpace,
    We don’t kill explorers like we used to. So we aren’t going to send astronauts to “see if they can…” Everything needs to be shown to work before they go. And that means they’ll just be a flags and footprints mission, following a bunch of robot lander missions to prove their landing sites, test their ISRU, etc. In which case, for research, you might as well stick to the robots.

    What will be interesting is if SpaceX can lower launch and operations cost enough to actually meet Musk’s goal of affordably sending people to Mars. Because once they do, it should then be within reach of privately or semi-privately funded “explorers” to do their own flags’n’footprints mission to Ceres. Buy a used MCT that SpaceX is retiring or replacing. Buy an old Bigelow greenhouse module to add. Upgrade the ion-drive or increase the fuel tanks. Buy an old Dragon V2, upgrade the Superdracos or increase the fuel tanks to increase the delta-v by about 50%. (Or buy a second set of Superdraco thrusters and tanks and build a cheap descent stage to attach under the Dragon.) Launch your crew and supplies on a regular SpaceX flight, prep the modded-MCT and then… go.

    Probably see a lot of old style (stupid/dangerous) exploration done that way, once the price drops enough.

    Similarly research programs that aren’t “The Space Program”, they are just astronomy for example (it just happens to be cost effective to build on the moon, no different than building in Atacama or Antarctica.). Or it’s just “emergency repairs”, because it’s cheaper to send a guy to fix your billion-dollar satellite/etc than build and launch another one. And cheaper to send humans than build specialised robots.

    That’s the only way we will see significant progress in space.

    Proposing missions without that drop in cost, whether moon, Mars or Ceres, doesn’t do that. It’s pretending to be explorers, pretending to be workers.

  5. George Turner says:

    For checking 3 to 5 RPM’s at 0.25 G (1.03 G apparent at a tilt of 14 degrees), you could just find a parking lot and drive an RV in 60 to 160 foot circles at 11 to 18 mph. Add a couple of steel cables attached to a central post, tilt the suspension 45 degrees, pull 1 lateral G (1.414 G perceived), and drive 35 to 20 mph and you could use the same 60 to 160 foot diameter parking lot to test 6 to 10 RPM spin rates.

  6. johnhare john hare says:

    Paul,
    Haven’t had time to read the whole thing yet, but it seems that 5.4 rpm is known to be a solvable problem, and 12 rpm is know to not work even with long adaption times. 7 rpm sounds like a good start point. Somehow I got 1.21 felt gee at the banked angle for half gee. But then I’m a bit tired and my math is fuzzy at the moment.

    George,
    The RV solution sounds like a good start point. I am in the concrete business and I would bid a 65 foot diameter (close enough to 20 meters) tilted concrete ring with inside curb for tracking at something in the $15k range including earthwork in the labor and materials. A really old RV could handle the 20 mph on the banked circle. Actually, at 20 mph, I might go with and earth berm and crushed concrete road for about $3k for labor and materials.

  7. johnhare johnhare says:

    Nevermind I found stupid math mistake.

  8. George Turner says:

    Uh oh. Was it mine our yours?

    Also, are people equally sensitive to disorientation in roll, pitch, and yaw? Low-G centrifuge experiments on Earth would mostly be providing a yaw error, but a space station would primarily influence roll and pitch (as a seated pilot would perceive it).

    As for issues with Coriolis forces, I would ignore them. Having ridden across the US on Amtrak, neither the passengers or employees have any problem with motions not happening as they would in a stationary rail car, even when you have to stagger around because of all the jostling on rough track. We’re fine with very large discrepancies in the perceived rules of local motion, whether on foot, horseback, car, train, or boat, as long as the inner ear and eye don’t go to war over who is right.

  9. johnhare johnhare says:

    My mistake on gees felt at half gee centrifugal. I don’t think a rough ride would be acceptable for true data on living and working long term in a centrifugal field.

  10. born01930 says:

    It could be similar to getting your sea legs. I adjust rather quickly to a pitching boat but have a harder time when coming back to land especially if the trip was several weeks. In many cases during WW2 Uboat crewmen had to be carried off the boat, unable to walk on hard ground after a patrol. I think you could see parallels to a spinning habitat.

  11. MBMelcon says:

    Some of us never get sea legs, even after a month on board.

    As long as you are building a merry-go-round, have several rings. 6-m and 14-m rings would have the same rotation rate as a 10-m ring, but +/_ 40% the radial acceleration, in case that turns out to be important.

    Youtube shows an ~4 m radius carousel rotating at 5rpm. No one was ill. http://www.youtube.com/watch?v=hucvzUeJGE. SF’s runs at 4 rpm.

    If the tip speeds are sufficiently slow, the lab could be built as a circular boat on a toroidal hull. Low friction, smoother and quieter than riding in a vehicle.

    -MBM

  12. George Turner says:

    One other thought for getting zero-G spin data is to do it in a vomit comet. If you added a horizontal (vertical axis of rotation) centrifuge you could perhaps get some extra data about standing and walking in low-G artificial gravity.

    Zero Gravity Corporation flies a 727 with a fuselage width of 11 feet six inches, which perhaps wouldn’t be that useful for the endeavor. Other options are a 777 (cabin width 19 feet), a 747 (cabin width 20 feet), or the still-flying NASA Superguppy (cabin width 25 feet), which could allow the centrifuge to be mounted in a gimbal so the aircraft’s pitch-over doesn’t affect the experiments.

    Another possibility is to use the radome on an E-3 AWACS, which is 6 feet thick and 30 feet in diameter. There is reported to be at least one E-3 in the Davis-Montham boneyard, and in 2009 an E-3 broke a nose wheel, had the front catch on fire, but suffered no damage to the radome or mounts. Perhaps that’s still sitting around somewhere, and the boneyards have a whole lot of E-2 Hawkeyes with 24 foot domes that would certainly be cheaper to operate. Obviously significant modifications would be needed, including pressurization, but a repurposed scrap aircraft might be a cheap way to get useful data.

    If I was a billionaire looking to go to Mars, I’d look into these quick-and-dirty partial-G experiments.

  13. Paul451 says:

    There have been vomit comet experiments one rotation. However, the time for each arc is not sufficient to get a meaningful test for how humans would respond to spin gravity. By the time you spin up your subjects, you’re near the end of the arc and it’s time to spin them down again for the pull-out.

    [The intent of the research was to find out how quickly capsules (Mercury/Gemini) could rotate without the astronauts losing their ability to see/operate the controls. But that is a test of the change of rotation rates (spin-up, spin-down), not constant rotation.]

  14. George Turner says:

    It sounds like that was also testing hand movements, not balance in artificial gravity. With a wide-body aircraft I would spin them up prior to the arc, probably having them lay down with their feet against the side of the cylinder, and then see if they had trouble walking around and doing tasks during the arc before leaning against the bottom wall for the pull out. If a station had a non-rotating section attached to a rotating section, this could also check for issues with the rapid and possibly frequent transition in spin rates.

  15. born01930 says:

    Why not grab a few of those carnival rides..Roundup I think it was called that used to spin and press you against the wall then the floor would drop out.

  16. johnhare john hare says:

    Lease them while they are unused in winter quarters and it should be fairly cheap.

  17. George Turner says:

    Quick thought for next winter. How hard would it be to put a mobile home or Airstream trailer on ice skates on a frozen lake and rig up a long arm to pull it around in a circle?

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