Thursday, June 16, 2011

The Stanford torus

Back in the '70's when dreamers were dreaming big dreams about Colonizing Space, one of the most popular colony designs was the Stanford Torus, named for it's torus design and its designers place of work.

The Stanford Torus is a tidy wheel design that spins at 1RPM, it's the shape of a bicycle inner tube 2km in diameter, and provides an artificial gravity as strong as that of Earth to its residents, who live in the inner tube with their heads pointed towards the axial, their feet planted on the inside of the outer circumference of the inner tube wall. The original design had a tube with a width of 130 meters which, with the tube circumference of 6.2 kilometers gave an area for the inhabitants of 832,000 m^2 or 83 hectares of living space.

The population of this colony was proposed to be 10,000 people, plus their pets and livestock, it was originally suggested that it be at L4 or L5, though it was later suggested that the ideal location would be at an orbit about Earth in 2:1 resonance with the moon so as to be positioned between the Moon - the source of raw material - and geosynchronous Earth orbit - the destination of its manufactured product - solar power satellites (SPS).
Being so deep in space the colony would be without the protection from the Earth's magnetic field that protects people and facilities in Low Earth Orbit, so the colony was to be protected by a several meters thick layer of slag or waste from the lunar regolith processing facility, this shield would weigh about ten million tonnes.

I like the Stanford Torus, it is easily the lightest of the various designs that the Stanford team studied, and unlike a cylinder design, it didn't have a pointless kilometers deep atmosphere, and the small diameter "inner tube" meant far lighter construction than a big diameter cylinder. it's an elegant design that's an efficient use of mass, and it caters for a population that I think is realistic, a smaller population would struggle to support a feeling of being a civic community, a much larger population would take time to build, and such a large colony would require a far bigger investment than would be necessary for a first step to establishing a community that was truly living in space.

I like the Stanford Torus, but I don't think colonizing space will be done on the back of a huge investment in mining the Moon, launching the mined regolith into space, catching and processing that regolith into solar panels, microwave emitters and girders, and then constructing SPS's tens of kilometers across which are then moved to GEO. It's all too big a hurdle, too much risk, too much investment all at once, every step of which has got to work.

The Stanford Torus I remember was a place I'd want to live, even if a small section cost ten million dollars, I imagined that there would be no shortage of super rich people, bored with the sterility of Beverly Hills, who'd jump at the opportunity to spend far more than ten million to live there, and I remember thinking that even if I couldn't live there, I'd sure want to visit it some day.


  1. Hello Andrew,

    I've added a powersat spreadsheet to my site, hope it's usefull to you. One question I have is: how many people does it take to maintain a 1000 MW powersat once it's built? I'm guessing 2 at this time. That would put a minimum of 45000 people in orbit at all times, for a 100% powersat economy. 4 Stanford toruses. A basis for future development?

    My site:


    Michel Lamontagne

  2. Hi Michel, I think your spreadsheet is excellent! I think your guesses are fair, the power sats would probably be at least 10GW each, apparently if they're in GEO 5GW is the minimum practical size because of microwave beam spread, in the much lower Sun Synchronous orbit that would probably be less of a problem, but that orbit, at 600km altitude only has a circumference of about 44,000km, so to get reasonable space between the power sats to reduce the number of them the bigger they are the better. Where did you get your total weight estimate for the Stanford Toruses from? I've been playing with numbers and a million tonnes for a population of 10,000 is in the middle of what I was getting.

    I've no idea what size the maintenance crews would need to be, though I think if you're constantly having crews rotating up from Earth their accommodation could be far more spartan than at only 10,000 per Stanford Torus, that 10,000 is for luxury LIVING conditions. Trying to put some context to population/tonne I keep thinking of the Queen Mary2, 150,000 tonnes, with over 6000 passengers and crew.

    Regards Andrew

  3. Hello Andrew,

    100 tons per person :

    60 m2 per person of hull area
    5 tons per m2
    300 tons per person in a classic ONeil colony setting
    Divide by three because the workers are on shifts an there are no children (this bit is really a guess :-) ).
    100 tons per person.
    About 4x as heavy as the Queen Mary ratio, (Good image by the way, very graphic) perhaps a bit optimistic...


    Michel Lamontagne

  4. Hello Andrew,

    Thanks for the 10 gW tip.

    However, at my first ratio of 2 per powersat that puts only 10 000 people in space. Not as much as I’d like. I’m trying to think of an Earth analog. How about an Australian ( or New Zealander) sheep farm? Google says 3000 hectares on average, or 30 km2. Almost the same as a powersat! How many people on the farm, including migrant workers? 10?

    That would work out to about 20 000 people in orbit, or two Stanfords.

    Does 10 people on a sheep farm seem like a likely analogy?


    Michel Lamontagne

  5. I think the farm analogy is too foreign to solar power satellites to be useful.

    The O'Neill vision for the Stanford Torus was to establish communities in space, you can read T. A. Heppenheimer's book free on-line here:
    With communities typically only a small proportion of the population is directly involved with the industry that supports them all (in New Zealand only 5% of the population is directly involved in agriculture, though agricultural products make up the majority of our exports) if you had 10,000 involved in making and maintaining power sats, add in their families and then multiply by 5, you're probably close to the space population, now if tourism was also a money earner, and rich retirees were also living there, you could multiple the number of those people by 5 as well, it's easy to get to a population in the low hundreds of thousands - And just think what such a large space based population could do to push out the frontiers!

  6. Hello Andrew,

    Thank's for the link, i've been using it for a while though, great ressource.

    Communities vs commuting. I'll have to do some research. Perhaps i'll fire up another spreadsheet!

    Has anyone done research on life extension in low gravity? On mice or some such, perhaps? That would be a driver for space occupation!


    Michel Lamontagne

  7. I don't know of anything in the way of research on low rather than no gravity on health, on mice or man. But as I get older the idea of living in a slightly lower gravity has some appeal!