Space

The Space Studies Institute

21 Comments

…is under new management. They want to reenergize it, and start to push the technologies we need to actually develop space. If you still want to contribute and get the deduction for 2011, you have two more days to do it. It’s a worthier cause than ever.

21 thoughts on “The Space Studies Institute”

  1. Earlier SSI had endorsed solar power satellites as a lunar export. Is this still their thrust? I don’t see solar power sats becoming competitive with fission any time soon.

    Near term, the only remotely plausible lunar export I can imagine is propellant from the poles. If I saw SSI moving away from SSP and towards plans like Paul Spudis or Bill Stone, I would be happy to donate to their organization.

  2. The attention of SSI will be focused upon the technological and economic underpinnings of space settlement. SPS may play a role in that, or not – that’s to be determined. But space settlement can’t be based on a monoculture of industry.

    You will see we’re going to work on some key technologies related to settlement. Hopefully, we’ll be able to make some announcements within a few months.

  4. Mr. Waddington – Interesting article. However, there are a few problems as noted in the article itself – it shuts down in cloudy weather, which a microwave system would not.

    I can also see a potential problem with a 6MW IR laser beam!

    1. The idea is interesting but given the state of development and costs, I’d say the technology isn’t ready for commercial application. He said the system could deliver about a megawatt with existing efficiencies, rising to 6.4 MW with more breakthroughs and improvements. A 1 MW diesel generator costs about $100,000 to $150,000 dollars, while just launching this satellite on a Falcon 9 would cost over $120 million dollars, which would probably buy enough diesel fuel to run the 1 MW generator for 50 years. If you were selling the output on the US power grid you’d be looking at a payback period of over 100 years just to pay for the launch, and the satellite won’t last nearly that long.

      But if long costs drop by another order of magnitude and his efficiencies go up, it should be a workable scheme.

      1. There are times and places where conventional power is much more expensive, or not available at any cost. During World War II, when gasoline was being ferried by air over the Hump, there were times when it cost over $1000 a gallon.

  5. Actually most of the technology needed for spomes is already available, thanks to advances in other fields driven the market forces. But there is one huge question, a potential show stopper that needs to be answered and that is if humans will be able to reproduce in artificial 1 G environments. Based on Dr. Einstein’s famous thought experiment there should be no difference between gravity created by acceleration and gravity resulting from the accumulation of matter. But in terms of biological systems this is still a theory and it would be nice having some experimental evidence to support it give its importance to the question of space settlement.

    A quick way to do so would be to tether a Dragonlab to the upper stage of a Falcon and spin it up to 1 G. Then see if mice in the Dragonlab would be capable of successful reproduction for 2-3 generations, then returned to Earth to see if there are any differences between them and a control population. You could probably also develop a biosat for the Falcon 1 to run the experiment.

    If the mice reproduce successfully then there would be no show stoppers for humans to expand through out the Solar System and the galaxy beyond. But if, after repeated attempts, they fail to then you would have a huge barrier to humans spreading beyond Earth, especially if experiments in reproduction on low gravity worlds are also unsuccessful. On the other hand, if there are differences between artificial 1 G environments and natural G environments it would pose some interesting questions for physicists to study.

    Hopefully this is what the SSI is focusing on.

    1. Perceptive.

      I’d add that not only do we need specific technology, but tech that is individual and small group sized. One wants to be able to grow settlements in an organic fashion rather than have to have them spring full grown from the head of Zeus, so to speak.

      1. I agree 100%. In fact Kevin Greene and I have a paper/presentation scheduled for ASCE Earth and Space 2012 on an evolutionary approach to space settlement design using the Moon as the first step. The early focus of Dr. O’Neill’s on cities in space was one of the chief weaknesses of his proposal. It took nearly a hundred years for Boston to transform from a few cabins on the woods to a city of 10,000 and 250 years to pass a population of 100,000, becoming a city the original Plymouth pioneers would probably never recognize let alone be capable of designing. The same will be true of space habitats. The key is to first get a permanent population of a few hundred families established in space, then allow normal population/economic expansion to take care of the rest in ways its difficult to predict. If history is a guide the result will be as much as a surprise to current generations as modern Chicago would be to Jean Baptiste Point du Sable.

        1. There are several problems with O’Neill type habitats, especially in the beginning.

          They don’t scale down well, and until the hull is completed, pressurized, and spun up, all you have is a construction site with no habitable volume of any sort, at least at any fraction of a G. Given how projects that are Apollo repeats are getting strung out with multi-decade completion dates, a huge habitat with that kind of internal volume will take virtually forever to get rolling. I advocate using a cylindrical tube and packing everything in like sardines, spinning it like a baton.

          Second is the suggested habitats’ use of mirrors to collect sunlight, shining it on vast internal spaces where crops are grown. That creates problems with spin-axis optical alignment and having the mirrors spinning at high G’s. There are workarounds,, but those are also large scale structural engineering feats.

          Given that sunlight in space is only about 90% as efficient at growing plants as sunlight at sea-level (on an equal power basis due to extra UV and IR), and assuming your efficiencies are 98% for bouncing off a mylar mirror, 92.3% from reflecting off both sides of a window, 97% transmission through 6 inches of glass, and 90% because of all the structural frames that support the panes, you’re down to about 71% efficiency. Sea-level sunlight is only about 30% efficient for plants, so the total system is about 21% efficient at growing plants compared to using pure red (660nm) and blue (about 440 nm) light shining directly on them. The new Osram red and blue power LEDs, at 61% efficiency, powered by solar cells at just 33% efficiency, already exceeds this.

          Additional advantages are that your solar cells don’t have to rotate with the station or bare any precise geometric relationship with it, so you could align your spin axis perpendicular to the ecliptic and keep the solar cells pointed at the sun.

          You no longer have to have a huge, empty, internal volume for the crops because you can light them where ever you put them, such as in densely packed, vertically stacked hydroponic racks. The dense pack means the shielded volume plummets, as does the mass of required shielding.

          You no longer have to discard light for half the day so people have some semblance of normal day/night cycles, so your solar cells can be lighting twice as many plants (half on, half off at all times), and the day cycle timing of each species and crop can be done individually with a cheesy 24 hour timer. That also eliminates all the moving parts of a mirror system which are required to emulate a normal day cycle.

          Since the solar panels aren’t swinging around at high G’s, they can be repaired, replaced, upgraded, and expanded as needed. Importantly, you can start growing some plants as soon as the first solar panel and LEd system is mounted, whereas in an O’Neill colony you can’t even start until the whole station is completed. Even more importantly, the system scales down to any size, even to providing a partial-G grow room and space for a single astronaut.

          And assuming that the plants will be at 1G, you can test the whole system on the ground because it’s just solar cells in 0G, which we’ve been doing for decades, LED grow lights, hydroponics or dirt, and water.

          The one caveat is that the system will be dumping a lot of energy into a small space, so the grow rooms should allow the warm air to rise toward the spin axis in a large vent, then hit downcoming pipes with radiators to cool it, naturally descending back down to be reintroduced at the bottom of the grow rooms. So it uses natural convection to maintain proper air temperatures, and by circulating the air through unshielded pipes, perhaps with a few areas of UV transmissive glass, any airborne pathogens should get effectively irradiated.

          I haven’t yet thought of a cheaper system.

          1. George,

            Yes, using solar and/or nuclear energy to power lights in individual production chambers is far more practical and efficient than the Rube-Goldberg mirror arrangement, something Issac Asimov realized in the 1960’s when he wrote his classic article on Spomes. That’s one of the reasons that an Asimov model for space habitats is far more practical than the O’Neill model. Another is that its scalable and the third is that the Asimov model takes advantage of the ability of being able to use constant small levels of acceleration outside of the Earth’s gravity well to make the habitats mobile allowing them to transport themselves to the outer Solar System where the real bonanza in resources is.

            Another advantage of agricultural production chambers is that it allows you to optimize the lighting and gas mixture for the type of plants being produced in them. Lettuce for example will thrive under continuous light while tomatoes require a diurnal cycle to produce the best yield.

            However hydroponics is yesterday’s technology since research has shown that aeroponics is an order of magnitude more effective. Not only does it use far less water (from 10 % to 5%) then hydroponic and geoponic systems but its allows the roots systems to maximize gas exchange.The result is that not only do the plants grow faster but you are also able to greatly increase their density per square meter allowing plants to make maximum use of the light they receive. Since the density of nutrients in the water is the same as required for hydroponics this also translates into a 90% to 95% reduction in the nutrients needed for plant production. Aeroponics also is suitable for critical crop plants like corn that will not grow in hydroponic systems. All in all the advantages of aeroponics has basically made hydroponics an obsolete technology for high yield agriculture.

            Research by NASA on the Shuttle, Mir and ISS on aeroponics (NASA actually pioneered aeroponic technology) shows its well adapted to the space environment. That also brings up a further advantage of production chambers and that is you they allow you to vary the amount of gravity in them to maximize plant yields. For example NASA has found that lettuce grows far faster in a zero G environment then in a 1 G one, so you would put the chambers for Lettuce on the axis where you have no gravity. Other plants like beans that are more productive in a gravity environment would be produced in chambers located towards the rim.

            BTW the advancement of aeroponics research by NASA has created one of the spinoff success stories of the Shuttle era creating a new field of high performance food production. Research showed that not only are aeroponics systems are far more efficient then hydroponics and geoponics, but that the exposure of roots to air virtual eliminated disease transmission between plants further increasing yields. Aeroponics is now being used extensively by firms doing genetics research on plants and for the emerging biopharma industry. A number of firms are also working on introducing it into the commercial greenhouse industry where it would allow greenhouses to greatly increase output while reducing their requirements for water and labor. It would also greatly reduce their effluent output eliminating a number of the environmental problems associated with commercial greenhouses. Maybe someone with time like Rand will do a popular article on it, using it to illustrate some one of the successful research spinoffs made possible by the Shuttle.

          2. Oops. I was classing aeroponics as a subset of hydroponics because most people don”t know the difference. I’ve used aeroponics with an ultrasonic pond fogger for misting and it worked great! I’ve been wondering what would happen if you used an enriched oxygen environment on the root system, along with the usual enriched CO2 environment on the leaf system.

            Anyway, a couple of other tricks I would recommend with LEDs. One is to use the tight beam lenses (I built a water cooled Luxeon III rig with 5 degree beam spreads so the light came down vertically) and then, perhaps once or twice a day, cycle each LED and see if it’s hitting a leaf. You could either have the plants mounted to an array of photocells or use a simple color camera to compare the image to a reference field that didn’t have a plant in it. Using such a system, you wouldn’t waste so much light on young plants that haven’t filled out yet. They’d basically grow in their own slowly expanding spotlight.

            The other idea is to keep your LEDs very cold, because their efficiency goes up by 20% or more if the junction temperature is kept very low. On one of my rigs I mounted them to 1″ square aluminum tubing and ran cool water through the tubes. Running some sort of low-freezing point food-safe fluid, chilled by external radiators, would be ideal and seperate out the LED waste heat from the general airflow.

            A final idea is putting some of the LEDs on controllable swivel heads so they are automatically aimed at the plant in a pattern to maximize average illumination, coming in from the sides or even from underneath.

          3. George,

            That is an interesting method and I could think of some good uses for the waste heat in a space settlement. What I wonder is if the increased efficiency would be worth the increased complexity. Clearing some good research needs to be done in this area on trade offs in an simulated space settlement environment.

          4. There could definitely be some interesting studies. For early space stations I don’t think the hardware complexity is an issue if it buys you some efficiency, given how that will directly reduce the required solar panel size. That will directly drop the system weight and thus the total launch costs. But LED swivel heads might drive things the other way, given all the little electric motors and mountings, and whatever is built needs to approach 100% reliability. I think Osram’s breakthrough on LED efficiency (to 61% from the standard 25 to 28%) really moves things forward, as it cuts the solar panel size in half and cuts the waste heat per photon down to a quarter that of the current LEDs.

            It’s pretty common to use oxygen production as a measure of photosynthetic activity, and that might be an ideal way to compare different design solutions, perhaps in units of liters O2 per hour per kg of required hardware. A design competition would make a great contest, and I’m sure everyone in the grow-light and aeroponics business would love to get the bragging rights and free advertising. 🙂

            I would think the bigger worry is operational complexity that requires human intervention, since that takes astronauts away from other things they could be doing. You’d think all they should have to do is plant and harvest, but on a small station you could probably use a little remotely controlled robot rover with an arm and camera, letting schoolkids pick the fruit via an uplink from a web interface. It would have to be pretty dexterous to let them plant seedlings, though.

    2. “Hopefully this is what the SSI is focusing on.”

      You want spinhab research to see if centrifugal gravity enables us to survive and multiply in space. I’d like exploitation of volatiles at the lunar poles.

      Does the SSI advocate either of these? Who knows? Hudson’s letter is vague. If He wants donations, he needs to put together a sales pitch with more tangible, well defined goals.

      1. Hop,

        I presented the challenge of lunar volatiles to my manage students a few months ago, most of who work for major gold mining firms. They basically saw it simply as a question of getting the equipment to the Moon and finding a stable market.

        It terms of actual mining and processing they felt robotic mining technology being developed by Rio Tinto and International Nickel would be more then up to the job if transported to the lunar surface while most modern refiners are already moving to robotic systems to reduce costs and risks. As such the lunar workforce would only a few dozen at most, mostly repair techs with a few mining engineers/geologists.

        BTW the cost wasn’t as much an issue as space advocates think as the industry is already used to multi-billion dollar projects that take a decade or so to reach breakeven. But that is only because there are proven markets with price histories for the output, the key missing element for lunar volatiles.

  6. Of course we favor both. And I regard my letter as vague only in the sense that I’m not prepared to announce a project. When we are, we will be as specific as necessary.

    This newsletter was only to announce the reboot, not future projects.

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