back to article These centrifugal moon towers could be key to life off-planet

Japanese scientists are putting a new spin on human life in outer space with a proposal for centrifugal skyscrapers on the Moon and Mars. Kyoto University academics and folks at Kajima Construction, one of the largest building firms in Japan, have partnered on the concept, which they call "Luna Glass" and "Mars Glass."  If …

  1. Anonymous Coward
    Anonymous Coward

    And the first meteor strike

    what happens then ?

    1. aki009

      Re: And the first meteor strike

      ... Then we hope that there's a camera to catch the fireworks. It'll be top of the news for at least a few days.

      On a more serious note, this idea might have legs on Mars because the thin atmosphere provides some protection against meteors, but then again that also means there'll be storms. I personally think that there'll be plenty of things to kill everyone off earth, even without adding to them with something like this.

      1. khisanth

        Re: And the first meteor strike

        Storms on Mars are not as strong as on Earth due to the thinner atmosphere.

        1. Dave 126 Silver badge

          Re: And the first meteor strike

          Andy Weir, author of The Martian, states that the big storm that sets the events of his story in motion is his only deliberate exaggeration in the novel. He just needed a way to have his protagonist left behind on Mars.

          (But hey, Ridley Scott is as fond of flying debris, dust and particulate matter as he is of rain, stream and mist - and he films it all beautifully.)

    2. sambaynham

      Re: And the first meteor strike

      Forget meteors, what happens when the Principality of Zeon or somesuch invades? You're going to need at least three Gundams to defend that thing, and several hot-headed/isolated/genetically-engineered youths to pilot them. That just adds the the expense.

      This is a great idea on paper, but no-one's considering the practicalities.

    3. Mike 137 Silver badge

      Re: And the first meteor strike

      "People would live on the inner walls of the [glass] tower"

      Never mind meteors. You wouldn't want to drop anything remotely heavy, so no clumsy folk allowed on board.

    4. John Brown (no body) Silver badge

      Re: And the first meteor strike

      Meteors? I'd be more worried about worn bearings and everything juddering to a halt, possibly abruptly and catastrophically!. Not to mention the many, many other structural and engineering issues in just building it, never mind creating or shipping the millions of tons of materials needed to build it.

  2. DevOpsTimothyC

    Not a new idea

    Wow the bar to be a scientist seems to involve plagiarism these days. This sort of concept is FAR from new. The Stanford Torus from the 70's were the first main group I know of for in space, More recently Isaac Arthur has covered the design on his youtube channel years ago (I cannot remember which episode). If you look at Reddit there's a question there that is 5 years old

    1. John D'oh!

      Did you know

      Isaac Arthur's half-brother is Clarke Asimov.

      1. Zack Mollusc

        Re: Did you know

        and he drives a Robin Reliant

    2. Roland6 Silver badge

      Re: Not a new idea

      And all predated by Clarke...

  3. Zebo-the-Fat


    It would be interesting to what happens when the abrasive lunar dust eats away at the bearings (interesting to watch from a safe distance that is)

    1. Dave 126 Silver badge

      Re: Interesting

      That's some very abrasive dust, that. Formed by meteorite impacts, under a microscope particles look irregular and serrated. Without water, wind or motion to smooth them.

      Which is why a contactless magnetic bearing system would be a prime candidate.

  4. Hurn

    Dealing with two "down" directions might be tough

    If I'm reading this correctly, the centrifuge spins at 90 degrees from vertical, (meaning axis is vertical), so that primary "down" is lateral (towards the outer wall of the wheel).

    However, even given a spin going at 1 G sideways, there's still the "real" down to worry about - 1/6 or 1/3 G, 90 degrees from the primary down.

    Seems uncomfortable, or even dangerous.

    1. Ken Hagan Gold badge

      Re: Dealing with two "down" directions might be tough

      That's why the outer wall is curved like a wineglass. There's only one down.

      1. John D'oh!

        Re: Dealing with two "down" directions might be tough

        Dammit you beat me to it, although I wasn't going say "wine glass". You are obviously feeling a bit more inspired than I.

      2. jmch Silver badge

        Re: Dealing with two "down" directions might be tough

        "That's why the outer wall is curved like a wineglass. There's only one down."

        My first thought was exactly how to deal with the 'real' down vs the 'artificial' down. But curving the outer wall won't completely solve the issue either. The closer you are to the center, the less centrifugal component you have and also the 'flatter' the floor will be (ie closer to horizontal on the real surface and so higher component of the moon/planet's gravity).

        In real terms that means that there is a narrow band of usable space where gravity is around 1G plus or minus a bit. You can't get further away from the center of rotation than the 'sweet spot' since at that point the tower wall/floor will be almost vertical with respect to the planet surface. Closer to the center of rotation, artificial gravity will be less, and the component of 'real' gravity will not be large enough to compensate (but I guess it might be possible to use these areas for storage, growing food or other activities were low-gravity is less of an issue).

        The other major problem is permanence, ie if the tower stops rotating everything / everyone that is not bolted down will fall. That makes stopping it for scheduled maintenance* a giant pain, and makes unscheduled stoppages a huge disaster.

        *and I hate to think what lunar / martian regolith would be doing to a spinning mechanism. On Earth you could use some overpressure mechanism to keep dust from blowing in, but in a place where atmosphere is a precious resource that isn't a good solution

        1. A.P. Veening Silver badge

          Re: Dealing with two "down" directions might be tough

          In real terms that means that there is a narrow band of usable space where gravity is around 1G plus or minus a bit. You can't get further away from the center of rotation than the 'sweet spot' since at that point the tower wall/floor will be almost vertical with respect to the planet surface.

          But you could have multiple of those bands above (reference to where the base of the cone is located) each other. And with extended walls (floors when it stops spinning), the crashes when it stops spinning won't be life threatening (unlike the reason for it stopping).

  5. Howard Sway Silver badge

    The 1g of normal gravity might feel nice and comfortable

    The view out of the window is going to make you feel mightily sick.

    1. steelpillow Silver badge

      Re: The 1g of normal gravity might feel nice and comfortable

      No worse than riding in a car or a train, you'll just get bored with the number of repeats almost equalling freeview channels.

    2. Tom 7 Silver badge

      Re: The 1g of normal gravity might feel nice and comfortable

      The 20s rotation could easily induce nausea - its one of those subtle things that could really mess with you.

  6. Anonymous Coward

    Not practical

    The idea of a space station rotating to produce artificial gravity dates to Von Braun (helped by illustrator Chelsey Bonestell) in the early 50s. It made some sense in an era when space stations didn't have to move to dodge debris.

    The idea of a spinning cylinder would also make some sense if you could bury the whole thing in a lined, pressurized tunnel (to protect it from Mars or Lunar dust).

    But the materials and surface infrastructure needed to accomplish this make it a valid thought experiment but an absurd idea at the practical level.

    1. Ken Hagan Gold badge

      Re: Not practical

      Rather less clever engineering is required if you bury the structure and treat it like a fairground ride. Most of the mass of the mechanical support could be stationary and embedded in the rock.

      Also note that you only need to provide 1G for the bit that people spend most of their lives in. Things like industrial or agricultural zones can make do. Also, humans can use avatars to go walkabout, so you probably need less living space than you think, even for an active lifestyle.

      1. the Jim bloke

        Re: Not practical

        Low gravity is only one of the stumbling blocks on the path to colonising space - and probably the easiest to clear.

        Others include getting materials there, keeping the vacuum outside of the habitat, and radiation in all its spectrum, are more immediate in effect.

        Building habitats below the surface is just far more practical.

        And definitely limit the scope of the centrifuge to human maintenance necessities - until such time your moon colony has sufficient surplus to support extravagances

        1. Bartholomew Bronze badge

          Re: Not practical

          As far as I'm concerned the first long term inhabitants of the moon, or mars, will end up living under at least 5 meters of dirt. This is to provide a similar level of radiation shielding that is provided by earths roughly 11 to 100 kilometres of air (~75% of the mass of earths atmosphere’s is within 11 km of the planetary surface. ~99.99997% of the atmosphere by mass is below 100 km).

          EDIT: We could bring graded Z shielding from Earth. But why bother, when the regolith is already there and nearly free (except for local shipping costs).

          1. DJO Silver badge

            Re: Not practical

            On Mars there's nice deep canyons which would shield most of the incident radiation. That would seem a good location to colonize.

            1. Bartholomew Bronze badge

              Re: Not practical

              I had to lookup the pressure on Mars in the deepest canyon (which is also the deepest canyon in the solar system)

              mars ground level 610 Pascal (equivalent pressure on earth would be at an altitude of ~43.1 kilometres which has an air temperature of about -12°C on earth).

              mars at the bottom of Valles Marineris (~7km down) 1200 Pascal (equivalent pressure on earth would be at an altitude of ~37.4 kilometres which has an air temperature of about -28 °C on earth - thought that was totally insane when I learned it as well, colder than higher up).

              earth sea level 101325 Pascal (To match that pressure on Mars would require going ~60 km below normal ground level. But at that depth the average temperature would vaporise all water and sublimate Iodine at about 473K ; 200°C ; 392°F if you assume the average ground level temperature on mars is around 223 K ; -50°C ; -58°F).

              It is about twice as good at blocking radiation at the very bottom of the deepest natural canyon on Mars, but even it will provide about 1% of the protection provided by earths dense atmosphere.

        2. GraXXoR

          Re: Not practical

          "Others include getting materials there, keeping the vacuum outside of the habitat...."

          It's surprisingly easy to keep the vacuum outside of the habitat... The difficulty is keeping the air in the habitat..

    2. Malcolm Weir

      Re: Not practical

      I reckon it's about as practical as O'Neill cylinders, perhaps easier to build since the scale is smaller, but more vulnerable to issues involving bearing wear and so on.

      Which is to say, not practical without some major technology steps first.

      But that Bezos guy has the cash to make (some of) them happen, so maybe...?

      1. Anonymous Coward
        Anonymous Coward

        practical but heavy

        So this has the challenge of a high mass, so it will be expensive and resource intensive to set the first ones up. You wouldn't probably want to have to flat pack that and lift it off earth.

        The bearings aren't going to need to be as exotic as you might think. Remember kids, Lunar gravity not earth gravity, and you only need to boost mars gravity, though that would be MUCH harder.

        I'd look at liquid bearings, which would have the main drawback of relative power ineffeciency, but could be compensated on lunar deployment with more solar panels. They are cheap, reliable, and probably easier to fab from local material. You can also use the bearing fluid to help heat sink the waste heat from whatever is maintaining rotation. Magnetic would also address most of the concerns and may see secondary synergies if they are trying to shield the living space. I'd just bury the whole thing though. No reason to live on the surface of either mars or luna, which is also an answer to the meteor/radiation problems to some degree.

        The lunar case is the more relevant as long term mars is farther off, and having heavy lift of luna will be more efficient than pushing everything off earth, so if we ever stay on mars it makes sense to set up spaceport on luna with an orbital gateway. As far as originality, the team never claimed to invent spin gravity, and while the back of the napkin though experiment may not be new, fleshing out the numbers is real and valid work, even if it's not realized for decades.

        The same was true for the pioneering work on the science behind space station in LEO. Dreamt, then designed, then tested back in the Gemini/Spacelab era, and nearly a generation later, realized as the ISS.

        1. Spherical Cow

          Re: practical but heavy

          I was about to suggest a mercury bath bearing similar to those used in some old lighthouses, but then I remembered the vacuum on the Moon will cause the mercury to evaporate if the bearing doesn't have a really good seal.

        2. Adrian 4 Silver badge

          Re: practical but heavy

          Don't use a central shaft, run the outer shell on lots of roller bearings. Then change them one at a time with the shell still rotating.

          1. Alan Brown Silver badge

            Re: practical but heavy

            given the kond of dust on the moon, you'll be replacing a bearing every 30 seconds - forever

    3. Adair Silver badge

      Re: Not practical

      And then there's the interesting effects of the Coriolis force on human beings when there is a relatively small radius relative to the centre of axis.

      I reckon someone's been licking a toad on this one.

      1. jmch Silver badge

        Re: Not practical

        I guess the answer to that is a gigantic km++ radius wheel turning relatively slowly!!

        That could work as a space station but maybe not so well as a surface solution

    4. phuzz Silver badge

      Re: Not practical

      The idea of a space station rotating to produce artificial gravity dates to Von Braun (helped by illustrator Chelsey Bonestell) in the early 50s

      Werner always did have good PR, however, Tsiolkovsky (of the 'Tsiolkovsky rocket equation') wrote about rotating habitats in 1903, and it wasn't even a new idea then.

  7. Dizzy Dwarf

    Stupid idea

    This is like one of those nausea inducing fair-ground rides, except that they only last for five minutes, then you get to stagger off and recover in the nearest hedge.

    It would work in free fall - in orbit. With a much larger diameter and a slower rotation.

    Not on the Moon/Mars, with their own existing direction of down. You'd just be falling over sideways all the time. Also everything would be steeply uphill.

  8. Paul Crawford Silver badge

    Ah, like The Ark in Space but hopefully without the giant parasitic wasp-things.

  9. sarusa Silver badge

    And then the bearings lock up, or the generator fails

    And everyone falls to their deaths. Maybe they land in the water only slightly stunned. And then a boat lands on them.

  10. Stork Silver badge

    I like the sailboat.

    Definitely one for my packing list if I move off Earth.

  11. Natalie Gritpants Jr

    Bonkers video

    Why would you want a yacht on the moon. Not like you can go anywhere with it. Also stupid is filling the thing with water which will make the entire building unstable. The minute everyone moves to one side for a party the extra mass will result in the building leaning that way and then tons of water will shift their too and drown everyone before the thing falls over and spills their corpses over the moon's surface. I think that's a good sequel to The Poseidon Adventure.

    1. J.G.Harston Silver badge

      Re: Bonkers video

      We're sailors on the Moon, we sing a happy tune.

    2. phuzz Silver badge

      Re: Bonkers video

      Mind you, all that water would make a great radiation shield in just the place you'd want one.

    3. innominatus

      Whose yacht? Larry Ellison's maybe?

      It was the right shade of red...

  12. Danny 2

    The Father Thing

    Dad died last year. The previous few years were a bit rough in terms of science fiction because he went off fiction. For example he wouldn't watch Picard because it was fiction, despite owning every Star Trek episode and movie. He loved 'Dark Matter' and tolerated 'The Expanse' because, who knows.

    I was bought up with a wheen of sci-fi books - your Brian Aldiss, your JG Ballard, your HG Wells, your Isaac Arthur, your Horselover Fats. All first editions.

    Weirdly the most valuable book he gave me was 'Franny and Zooey' by JD Salinger, signed by JD Salinger. It was pretty wrecked before I got it and I loaned it out until it was totally wrecked. I didn't believe it was a genuine signature because dad had faked the signatures of the moon landing crew on a record sleeve of the landing. But dad never knew who Salinger was.

    Apology for the eulogy.

    I think we should make artificial gravity 2g, so they are strong enough to kick our ass.

    1. Kane Silver badge

      Re: The Father Thing

      "Horselover Fats"

      Shout out for the Philip K Dick reference!

  13. Kevin McMurtrie Silver badge

    Stupid idea

    Let's face it, the only reason anyone wants to visit the moon is for a vacation away from gravity. Anything else can be reproduced on Earth.

    1. Malcolm Weir

      Re: Stupid idea

      Well, except for the gravity well/no atmosphere thing, yeah. Not a vacation, but a massive asset if you're building stuff, like (say) O'Neill cylinders...

      (Insert Jeff Bezos explaining why those are a better plan than colonizing Mars, at least as a first step in becoming a more-than-terrestrial species).

  14. AVR

    Is there any data on the effects of reduced gravity? We now know microgravity is bad, but is there solid reason to believe 1/3 or 1/6 G approx. has similar effects?

    1. Pascal Monett Silver badge

      We haven't been present long enough on the Moon to have any data on that.

      That said, it is probably not much better than zero gravity.

    2. John Brown (no body) Silver badge

      I'm also a bit concerned, as per the article, about the lack of research on children spending extended periods in low or micro gravity. I think we need to start sending children to space ASAP to see what effect it has on them. Maybe ask their parents if it's ok too. I'm sure the various ethics committees will be fine with this.

    3. Northern skeptic again

      One of the great disappointments of the research carried out on the International Space Station was the deletion of the centrifuge which could have started to address some of the questions around living in gravity between 0G and 1G, especially as Mars surface gravity is about 0.38G. There is just no data about what level of gravity is required to sufficiently mitigate the health issues. Also a lower level than 1G could potentially result in a more efficient design for spacecraft.

  15. Big_Boomer Silver badge


    All that water is going to start oscillating and before you can shout "It has nothing to do with tides" you will be swept around the inside of a big wine glass and get to be famous for drowning in the most ridiculous and expensive way imaginable. In zero-G spinning large diameter habitats make a kind of sense as there are no bearings to consider and all other rotations can be minimised. On the surface of a planet/moon your bearings are going to be carrying a lateral load as the planet/moon drags your great big centrifuge around with it in addition to the downwards load of the weight of the "wine glass". I know the Moon has only 1.625m/s² gravity, but even that is going to amount to a sh!tload of weight pushing down on your bearings given the mass of your "wine glass" and the water/land it contains. All in all, it sounds to me like someone ate the wrong mushrooms.

  16. jmch Silver badge


    Long-term (and I mean REALLY long-term) surely best to allow human colonisers on Moon / Mars / wherever to live for a few hundred generations without any artificial gravity to evolve from homo sapiens to homo lunaris or homo martianis who can really thrive in the local conditions. Having less radiation shielding would also probably speed up the process!!

  17. sitta_europea Silver badge

    Wouldn't it be cheaper, easier and more effective just to send some robots?

    Granted they'd have to be better robots than we have now, but it won't be long...

    1. Malcolm Weir

      Imagine, if you will, a global pandemic. But one that has a case fatality rate greater than, say, 50% (that's where Ebola seems to be).

      Or a large asteroid strike.

      Or a pair of lunatics throwing nukes at each other.


      Robots won't do anything for those (literal) "end of civilization" scenarios...

      1. John Brown (no body) Silver badge

        Unless, of course, without their human overlords directing their every action, they evolve into something "better" and go off to colonise the universe, wiping out any threats to their ever growing expansion. It'll just be a different civilisation to the one we would normally envisage for ourselves, not an ending.

  18. Anonymous Coward
    Anonymous Coward


    Good to know japan's universities are filled with fuckwits like the UK and USA.

    Hopefully they belong to the "fairy tale department" and not physics or engineering.

    A basic bit of "thinking" should be enough, even without doing any calcs, that this has so many problems as to be worthless and a waste of time.

    1. John Brown (no body) Silver badge

      Re: Nice

      "Futurologist" seems to be a job title these days. I think it's what people who want to be SF authors end up doing when they find they can't write for toffee :-)

  19. Anonymous Coward
    Anonymous Coward

    "[...] and how will it complicate birth?"

    How much does the use of a birth pool on Earth depend on the buoyancy lessening the effects of gravity?

    1. John Brown (no body) Silver badge

      The baby is "floating" in the amniotic sack through the gestation period. The mother, on the other hand, may never float in water until the baby is due and thus be subject to 1g throughout the pregnancy. Once baby is born, it also is subject to 1g, so the birthing pool has no effect other than whatever benefits the mother gets at that time.

  20. Lis Bronze badge

    This is one for

    thunderf00t I think. Must send him the url of this article.


  21. Mike 16

    Effect on inhabitants

    Not here to discuss the physical/mechanical problems, but the effect on human, and human cognition, has been studied:

    The Centrifuge Brain Project

    Or a bit further down the rabbit hole:

  22. J.G.Harston Silver badge



    life off planet


    off-planet life

POST COMMENT House rules

Not a member of The Register? Create a new account here.

  • Enter your comment

  • Add an icon

Anonymous cowards cannot choose their icon

Other stories you might like