Feedback and Discussion

This page is for general feedback and discussion of Space-Based Solar Power and related topics. Providing a medium for your voice to be heard about SBSP is one of the main goals of C-SBSP. Please share your thoughts and ideas using the Feedback and Discussion Comment Form at the bottom of this page.

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42 thoughts on “Feedback and Discussion

  1. Space Base Power.Plant Motor Engine Generator – Technology Submission – Novel Rotary-Turbo-InFlow Tech / Gearturbine Project – Featured Development

    Atypical InFlow Thermodynamic
    Technology Proposal Submission
    Innovative [TURBO-ROTARY]
    Novel (Fueled) Motor Engine Type

    -The Gearturbine comes from the contemporary ecological essential global needs of an efficient power plant fueled motor engine. -Power thrust by bar (tube); air, sea, land and power generation, work use application.

    *Have the similar simple basic system of the “Aelopilie” Heron´s Steam Turbine device from Alexandria, [10-70 AD] one thousand nine hundred years ago. Because; the circular dynamic motion, with 2/Two Opposites power [polar position] lever, and is feeds from his axis center.

    YouTube Video/10.30 min; * Atypical New • GEARTURBINE / Retrodynamic = DextroRPM=> VS to <=front; "Collision-Interaction Type" – inflow vs. blades-gear-move. Technical unique dynamic innovative motion mode. [Retrodynamic Reaction = When the inflow have more velocity the rotor have more RPM Acceleration, with high (XY Position) Momentum] Which the internal flow (and rotor) duplicate its speed, when activated being in a rotor (and inflow) with [inverse] opposite Turns. A very strong Novel concept of torque power thrust. At field explanatory example with a metaphor is like if a sailboat take the wind from his prow front to move; wind/inflow + knots/rpm + wind/inflow + knots/rpm + wind/inflow + knots/rpm + etc… = Acceleration x Acceleration = Exponential Acceleration. Whereas it has more movements forwards, it receives a frontal impulse still but to move more forwards. A present example of the implementation of the Retrodynamic effect is in the application in the accelerator (and collider) of particles that this in the border of Switzerland and France.

    -Shape-Mass + Rotary-Motion = Inertia-Dynamic / Form-Function Wide [Flat] Cylindrical shape + positive dynamic rotary mass = continue Inertia kinetic positive tendency motion / all the complete Rotary motor mass weight is going with the power thrust move circular direction.

    -Non-waste parasitic looses system for cooling, lubrication & combustion; -Lubrication & Combustion, inside a conduit radial position, out way direction, activated by Centrifugal Force-Fueled Injected. -Cooling; a) IN-Thermomix flow, & b) OUT-Air Thermo transference.

    -Combustion 2Two [Inside-Rotary-Dynamic] continue circular [Rockets] flames. Like two dragons trying to bite the tail of the [ying yang] opposite other.-Increase the first compression by going of flow reduction of one big circumference blades going pass to 2TWO reduced, very long distance (total captive compression) INFLOW [inside propulsion] CONDUITS [long flow interaction] [like a digestive system] Start were ends, in perfect shape balance in perfect equilibrium well balanced, like a snake bite his own tale. -4 TURBOS Rotary [inside-rotary-active] [In-Flow, Out-Flow] Total Thrust-Power Regeneration [Complete] Power System. -Mechanical direct 2two [Small] "Planetary Gears" at polar position. Like the Ying Yang Symbol/Concept. Wide out the Rotor circumference were have much more lever [HIGH Torque] POWER THRUST. -Military benefits, No blade erosion by sand & very low heat target profile.-3 stages of inflow turbo compression before combustion; 1)1-Turbine, 2)2-Turbos 3)2-Turbos. -And 3 points of power thrust; 1-flow way, 2-gear, 3-turbine.

    *The most innovative power plant motor engine project today. Higher efficient % percent. Next trend wave toward global technological coming change.

    Patent; Dic. 1991 IMPI Mexico #197187 – Carlos Barrera. – Individual Designer – Inventor and project owner. / All Rights Reserved. – Monterrey NL Mexico.

  2. A worldwide effort must be undertaken to use the fantastic energy of our sun to produce our electricity. We will encircle the earth with solar power stations that will collect and beam power via microwave to stations located on the world’s oceans. There, the concentrated beams will be received as electricity and through electrolysis will produce pure hydrogen. The hydrogen will be bottled and shipped to the land, perhaps in old oil tankers. People will use this free hydrogen to fuel their homes, vehicles and businesses, eliminating the need for a power grid.

  3. Awaken and Rise
    Cease, for a moment, in all your works, all you men and women of Earth. Mark your name upon this foundation, the New Age of Humanity! Affirm and make known to all your commitment to a world that has abundant and free clean energy, air, food, and water. A world able to use its wisdom to provide these necessary elements for life. A world where money does not equal worth. A world committed to equality, individual liberties, and a population allowed to find meaning and happiness in life.
    Humankind has become enslaved by war, toil, poverty, and the rule of despots, the rich, and the influential.
    The workers, the poor, the forgotten, the common, and the dreamers of a better world must awaken and rise up to speak with one righteous and mighty voice for peace, justice, equality, and life itself!
    Awaken and Rise, all you who would show compassion and understanding to your fellow human beings. Awaken and Rise, all you who feel a change in your heart. Awaken and Rise, all who feel the burden of a world gone wrong, a people heading for extinction, a planet beginning to die.
    Awaken and Rise!
    Shake off the shackles that hold your heart. Sign this petition for the survival of humanity. Read and question the manifesto” Free Energy Now, the Ultimate Human Right”. In this document you will find a path to follow and a plan for a sustainable world in which war and poverty are unknown and free clean energy for life is humanity’s gift to her people. Link to the site and share this idea and plan for humanity with your friends. Remember that you are one with humanity. Our responsibility in this time of turmoil and environmental crisis has never been greater.
    Awaken and Rise

    • Thanks, Robert. I hope the new look is a bit more readable, too. A NSS board member, Lt Col Peter Garretson, left a comment for me with a heads-up about the upcoming presentation of the IAA report. I was humbled that he was reading Citizens for Space Based Power.

  4. On 14 November the National Space Society (NSS) will premier the 3-Year, 10-Nation, International Academy of Astronautics (IAA) Report on Space-Based Solar Power.

    • Peter, thank you for bringing this major new report on space-based solar power to my attention. I now have a copy of the report and will post an entry letting others know about it.

  5. Question I have for serous discussion is:

    1. What are the biological risks of space based RF microwave solar power vs. IMHO far superior riskless space based laser solar power [Lawrence Livermore Nat. Labs, photovoltaic; thermal to make steam to run generators, or manufacture hydrogen].

    As to wireless RF hazards, download & listen to these MP3’s of this “Coast To Coast Am” radio show broadcast of 11/17/2009 [four “39 min.” hours without commercials; already checked for virus via Norton].

    hour one

    hour two

    hour three

    hour four

  6. FCC denies license for 1 W wireless power demo

    Experimental Licensing Branch
    445 12th Street, S.W., Room 7A-321
    Washington, D.C. 20554

    May 07,2008

    Attn: Robert S Gammenthaler
    Moon Society, Inc
    P.O. Box: PO Box 940825
    TX 75094


    Dear Robert S Gammenthaler,
    This refers to application, File No. 0219-EX-ST-2008, for an experimental authorization.
    You are advised that the Commission is unable to grant your application for the facilities requested. There are possible harmful interferences to mobile satellite space-to-earth licensees.
    Responses to this correspondence must contain the Reference number : 6379


    Experimental Licensing Branch

  7. Art,

    the used warm and cold water has to go somewhere, and the level at which it is released is another degree of freedom — or even two of them. I would release it at the bottom of the warm surface layer, which thus only gets a little thicker. Turbulence does this all the time already, so I would expect it to be harmless (says this amateur).

    About fertilization schemes, didn’t I warn that there are even crazier ideas? :-) That’s biology, which is a lot poorer understood still than physics, upon which OTEC is mostly based. (There is still a large part missing from the glacial/interglacial CO2 bookkeeping; that’s presumed to be biological too. One theory is actually iron fertilization by dust-laden winds from arid areas during glaciations.)

    – Martin

  8. Thanks, Martin…

    Why don’t you email him with a pointer to this discussion and ask if he wants to add his 2-cents?

    As for surface temperatures, this may be so but when you intercept the heat flow in a way that can influence tropical storm formation, you’ll almost certainly influence both the Madden-Julian oscillation and the Hadley cell activity. Of course, if all you’re doing is reversing the effects of CO2 forcing, that might be alright weather/climatewise, but that extra heat has to go somewhere, and where it’s going (except for the small fraction you get as electrical power) is the deeper ocean. This could have direct impacts on deep ocean biology and the THC, which latter could involve indirect effects on biology.

    There was a comment at RC a while back regarding pumping cold bottom water to the surface using OTEC, presumably if this “Palmén limit” caps temperature the effect would be to reduce evaporation rather than cool the surface. And it wouldn’t impact deep temperatures (if the cool water was well mixed at the top). But it would create a tropical fertilization process over much of the barren tropical seas, which would have a major biological effect. And anyway, that’s GeoEngineering, not power generation. I doubt you can get both at the same time.

    BTW, thanks for the mention of this limit. It may help me out with a problem I’ve been chewing on regarding the evolution of mammalian blood temperatures.


  9. Art,

    Actually it is wrong to talk about changing the temperature of the tropical ocean surface, like also the patent application does (and which I thus don’t take very seriously, scientifically). One doesn’t change the temperature that easily. It is actually stuck at a ceiling of 26-27 degrees C, called the Palmén limit (sorry, no good link at hand). What bounds it is the feedback effect of more efficient evaporation carrying off the excess energy.

    Adding energy to the ocean surface will just lead to increased evaporation, and eventually to enhanced formation of tropical storms. This is the mechanism by which the current anomalous greenhouse forcing is producing increases in tropical storm activity (it appears their numbers don’t increase, but the big ones are getting bigger).

    This greenhouse forcing is a reality, and will be with us for centuries. Anybody believing that this doesn’t already impact atmospheric circulation (the aspects you mentioned in previous posts) is dreaming. OTEC represents, on the ocean surface, just an opposite forcing, intercepting an energy stream that would have gone to the atmosphere, but without changing surface temperature. And there’s a lot of harm to undo before it comes to generating new harm :-)

    BTW Carl Wunsch is an oceanographer that might have opinions on this.

    – Martin

  10. Don’t worry, there are even crazier ideas ;-)

    The reality of the thing is, if you are moving this large amounts of energy around within the climate-ocean system, knowing what you’re doing is no longer a luxury — independent of the precise technology. Space power has the advantage of moving no more than strictly needed, but the disadvantage of a net addition of energy. I am confident it can be done without causing harm, but we need to understand it.

    Unfortunately in this day and age, even insight is a suspect commodity :-(

    (And installing permanent forcings without this insight, like we’re doing all the time now, is even worse!)

    BTW doesn’t anybody check patent applications for prior art anymore? When I was little, you even had to build a working prototype…

  11. I’m really, really, skeptical. I suppose if every pumping station was “smart” and could have its activity adjusted dynamically and there were reliable models to predict the outcomes and select a pumping pattern to achieve the desired one, it might be possible.

    But messing with tropical surface temperatures would almost certainly affect the Madden-Julian oscillation, with consequences that are unpredictable today.

  12. Art,

    the trouble with current OTEC is that all working implementations are
    small scale. So modelling is our only recourse at present.

    It’s called ‘oceanography’. Which already tells you something about
    where it comes from: descriptive rather than analytical :-( Current
    status is better than that though. What we need are the same coupled
    atmosphere-ocean models the climatologists use.

    Yes, it’s true that cultural change hurts (like it did in the West, and
    still does for some, cf. evolution denial etc.), which can be exploited.
    Adding oil to the mix doesn’t make it any nicer.

    For rescue operations vulnerability of large installations isn’t an
    issue in the same way, and there, space relayed power could have a place
    — if somebody can be found to pay for it.

    – Martin

  13. Martin…

    My concerns about OTEC come from my ignorance of the actual processes and energies involved. It could be very robust to 20 TW, or it could be sensitive to 1 TW or less, I don’t know. IMO the best thing would be to find somebody who’s an expert on THC and describe the process and proposed energy (extraction) levels and see how hard they wince.

    Do you know anybody like that?

    I could try it with a marine biologist I’m slightly acquainted with, but it might be better to start with and oceanologist (is that the word?)

    As for the cost of energy, my own observations suggest that energy is often a “facilitator”, that is its easy availability allows new industries and business models to develop, replacing older less efficient practices. Consider how much the success of Amazon and on-line shopping owes to cheap fuel for UPS.

    Thus, my bias is always for an aggressive effort to keep energy readily available at the lowest cost possible. Of course this has to be balanced against the cost to the environment, which is why I’m so hot for SBSP ASAP. That way energy can grow almost without limits (well, we’ve both calculated the limits at RC, and they’re pretty distant if not unlimited).

    As for forward operation, IMO that’s inevitable. Conservative members of more traditional cultures are going to blame the West for the changes brought about by their own people, so there’ll always be somebody blaming us, IMO. But don’t forget emergency rescue operations (e.g. Bangladesh).


  14. Art,

    to return to your concern about the impact of OTEC on global ocean and atmopheric circulation, I must say that it seems a bit exaggerated to me. First of all, yes the models are uncertain, but they are getting better all the time. Secondly, the expansion of capacity would be gradual, not an all-or-nothing thing. If at any point, anything happens we don’t like — in the models, or in the correspondence between models and reality — we can stop and revert. Thirdly, we have the degrees of freedom afforded by choosing the location of energy generating capacity.

    And lastly, already the current greenhouse forcing at the Earth surface is 2 W/m2, or 1000 TW. Don’t you think we could hide -20 TW over part of the Earth surface in there, and even produce a better climate to boot? :-)

    Then, about cost. I see in the thinking about space power too much the implicit assumption that it should be cheap and abundant, whereas I would argue “affordable and sufficient”. I see that also in Coyote’s thinking: the only way to justify expensive space power is for forward operations. I think that is to limiting. The single greatest contribution to American security would be energy import independence, making such forward operations unnecessary at the source. (And they are not cheap, are they? Another cost item not making it to the price tag. Again: think affordable, not cheap). Coyote certainly sees this, but does it convert to a compelling sales argument?

    – Martin

  15. I do doubt (but that’s something to sort out) whether the added engineering complications and costs of operating at sea are worth it when not actually extracting sea energy.

    Perhaps. I tend to be skeptical that political problems will be solved just because it would make fixing the CO2 mess easier. Most of the ocean has nobody living there, and there are many parts with little or no ecology, different from deserts, which all have their own.

    I just posted a link to a company with another solution to the storage problem. I still think I like flywheels best (for the surface, unmanned space applications may be better off with solid-state capacitor storage when needed at all), but this Vanadium Redox system looks pretty good, except for the losses.

    Re ionic/plasma engines, I’m beginning to like the idea of lasers for that. I entered a long post on the Technical Discussion thread which will presumably appear when the moderators get around to it (they’re pretty slow). The basic idea is to generate a laser beam whose photon energy is just a little more than band gap of a PV system, which eliminates much of the loss. I calculated 15 meter apertures for both sending and receiving from GEO, which is much better, IMO, for space ships.

    Too expensive for regular power (until we can use Lunar materials), but it might give the program a boost for military and emergency applications (think New Orleans).


  16. Good idea.

    I do doubt (but that’s something to sort out) whether the added
    engineering complications and costs of operating at sea are worth it when not actually extracting sea energy.

    As for land based CSP, I missed that you posted those (the Ausra link?). They claim to have the storage problem solved… but when using space relay, there would be no storage problem :-)

    BTW one app also worth mentioning: feeding LEO ionic/plasma engines. Would require a large relay reflector (to keep the receiver small), but it would enable much faster, or better mass ratio,transfers to geostationary orbit by eliminating the on-board power plant requirement, otherwise a big part of the mass budget. (Obviously this doesn’t apply to the self-transportation of solar power satellites, they bring their own juice.)

    – Martin

  17. Martin…

    I not only saw the CSP links, I posted many of them. I’m a much bigger fan of surface-based CSP than something like OTEC. And I really like the idea of using floating CSP stations beaming power into space, whence it can be beamed back to Earth.

    But in the long run we need something like 20 terrawatts of carbon-free energy by around 2050, and even CSP would likely have repercussions. Only SBSP has a good chance of collecting that much power without impacting the environment (IMO).

    BTW, I’m going to pass along your idea of beaming Earth-based power to a GEO relay back to Earth where it’s needed on a thread at Space Solar Power blog. IMO a synergy between the SBSP crowd and some of the people at RealClimate would be a help for both. We need more of the type of cold water Ray Ladbury can throw on enthusiastic projections, and we need it combined with the problem-solving potential at SSP.


  18. …and BTW about power from space being inexpensive, I don’t think so. Certainly not inexpensive enough for use in food production — which currently is surprisingly fossil-fuel-intensive.

    Also not as seemingly inexpensive as electrical power today, which fails to include all externalities into the price as we know very well. Energy will simply never become as cheap as pumping/digging it up, burning it, and letting it blow away. Affordable yes, but cheap, no.

  19. Art,

    10 terawatts? That’s an end-game concern for a reasonably prosperous 22nd century world fully dependent on OTEC for its electric energy. There’s a lot of figuring out to do, low-hanging fruit to pick, and choices to make, well before that.

    …and as experiments on live planets go, it’s no worse than the ongoing one :-/

    Consider that new technologies open new alternatives, while not developing forecloses them. Space Relay OTEC may be the first step on a ladder getting us access to space resources. For this to succeed we need operations in GEO to be almost as flexible as current Antarctic or continental shelf operations — a tall order, but from there on it gets easier.

    About 100 g/m2: ordinary, not space grade, chicken mesh, strong enough to hold real live chickens inside, is only a few times that, depending on maze size and wire gauge. In space one should be able to do better :-)

    Also, I would probably go for a larger disc with a lower power density, which would allow a smaller size transmission array on the sea (I still feel that large structures in space are easier than on the ocean). Although that might scare some folks…

    And what about solar thermal arrays on land? You saw the link on RC. They claim it’s cost competitive now. Existing technology. Space power relays would allow European power to be produced, e.g, in the Australian desert, Saudi or wherever — and no need for high-voltage cables under the Mediterranean. This would create a truly friction-free global electricity market, the dream of market economists.

    – Martin

  20. Even at 8000-10000 tons, it’s doable. If it’s less, that’s even better. At 104 Watts/m2, it adds up to a disk intercept of 200 GWatts, which is a good deal of power to be shipping around the globe. While the dollar price of transmission lines might be lower, the added flexibility and reduced footprint might well be justified.

    For OTEC, I’m more concerned about interfering with the heat balance in the Thermohaline circulation. Before betting the farm on this for major (>10 TerraWatts) energy, we’d need much more reliable models. Given the limits on models, it may not even be possible to predict with assurance the result of any specific strategy. We’d just have to try it to find out.

    A positive effect, but only for _really_ large deployments, would be a reduction in hurricane frequency/strength due to cooler tropical surface waters :-)

    It would probably also reduce the force behind the Hadley cells. Not something to “try it and see what happens”, IMO.

    Floating farms will probably become feasible in competition with more traditional types over the next decade, depending on development (and legal issues). With ready access to space-transmitted power, they would become even more economical. If they aren’t already mature at the time of the “scramble“, however, you’re probably right that there wouldn’t be time.

  21. 8000-10,000 tons? My feeling is that it should (and could) be less. It could then be a stepping stone to justify the development of launch and space operation technologies etc. Actual factories in space, including power plants, would be the next step on the ladder.

    As for OTEC interfering with circulation, I don’t see that. There are many technical challenges, but the only ecological challenge seems to be the CO2 in the deep water, that will be released to the atmosphere, unless it is pumped back down — the obvious remedy (the effect equals 1/3 of that of an equivalent fossil-fired plant). It might be though, depending on location, that releasng this water to the surface will cause ‘algal bloom’ with a net negative CO2 balance. As always, this should be planned carefully.

    A positive effect, but only for _really_ large deployments, would be a reduction in hurricane frequency/strength due to cooler tropical surface waters :-)

    As for floating farms, I am skeptical. Can this technology be scaled up to feeding billions, in an economical way, on an ecologically bankrupt planet without inexpensive fuels? Mature technology only gets developed over time if there is a motive to do so. In this case, nations would scramble to feed their people in this and other expensive ways — the deindustrialization I mentioned — and it wouldn’t be enough, as by then there would simply be too much breakage already in the Earth climate and ecosystem [note to self: find Limits to Growth on my attic; they didn’t mention climate change did they?]

    Anyway, early successful deployment of C-neutral energy generation on a significant scale, whatever the type, would shuffle this deck ;-)

  22. Martin,

    I see it as consisting of a large number of “tiles” mounted independently on actuators, like multiple-mirror telescopes in optical astronomy. The reflective property would be passive, the geometry active.

    I still think you’d be better off making each tile a “smart” phased array antenna, rather than trying to maintain that sort of positional accuracy (centimeters or less) across many kilometers. Besides, that gives you the option of re-beaming to several different receivers simultaneously. You could also mix in small orbital installations, both providing and receiving power.

    Remember that the raw material of “smart” stuff (processing power) is subject to Moore’s Law.

    I would build the initial installation as a sphere, so that as soon as power installations are set up on Earth, industry could be undertaken in space. At 100 grams per square meter, that’s 8000-10,000 tons for a 5 Km sphere, 800-1000 launches for an Ariane 5 ECA. Big, but not out of the question. Tests could be made of smaller antenna components on Earth.

    I’m not at all sanguine about OTEC, on a mass scale. Retargeting energy on that scale will almost certainly interfere with global circulation. The same goes for windfarms, IMO, although one climate scientist tells me the effect would be negligible. One of the reasons I prefer SPS is that just about anything else does redirect large amounts of energy in a completely interconnected system, with unpredictable results.

    “Moving feet” will probably happen as soon as it’s economical, but between robotics and the (probably) much cheaper high-G launch options, I suspect a good deal of industry could be placed in GTO and run from Earth.

    As for food, you may be right, but IMO floating farms will be well into operation by then, so there will be mature technology to address the problem, if anybody decides to build it.


  23. Art,

    Actually a prolate ellipsoid of revolution with transmitter and receiver locations at the foci :-)

    I see it as consisting of a large number of “tiles” mounted independently on actuators, like multiple-mirror telescopes in optical astronomy. The reflective property would be passive, the geometry active.

    You’re right about the footprint of course. But electric power, _properly generated_, would be only a small part of that, and, e.g., OTEC, which retargets natural energy streams, has an order of magnitude more power to offer than mankind will be able to use before bumping into other limits. And reducing the footprint will eventually mean moving “feet” — you know, those things with five toes — into space.

    Realistically speaking I am not sure however how any timetable for that could accomodate the coming collapse, which I expect for 2030-2070, roughly like the Limits to Growth (1972) foresaw. It will start with a failure of the agricultural production base, and once people understand what they are up against, it will have become unmanagable. An uncontrolled population reduction and de-industrialization in the countries most affected; and those spacefaring nations still able to do so may well move out to space to escape the threat of regional nuclear conflict on a basket case “Easter Island planet”.

    Not a nice scenario, but only acting now could still avoid it.

    About the accusation of selective deletion on RC, believe what you will — the platform has been flakey and overloaded during American daytime. I think it is projection by denialists of their own motives (I mean, credible peer-reviewed work to which Gavin et al. would not have a well thought-out response? Are you serious?)

    – Martin

  24. Martin, I’ll start with your second para:

    Alteratively, just space-grade chicken mesh on an ultralight carrier frame… you will need adaptive optics to focus the beam. This has been done for light,and for microwaves it would be easier esp. in microgravity.

    This was pretty much what I thought you were talking about. The problem is that it has to be parabolic (doesn’t it?) and extremely precise. You can’t just stretch it out on a rotating frame (that would give you a flat mirror).

    As long as your “three-dimensional arrays of large numbers of differently-tuned dipoles” are “smart”, that is they can keep track of their exact position and manage their own phasing, I would regard this as receiving and re-beaming. I wasn’t thinking of having it go through a full rectenna cycle.

    Actually, I don’t see a phased array on the high seas as that much of a challenge. Again, you just have to make each element “smart” enough to track its exact position (in three dimensions), and manage its phasing appropriately.

    As for RC’s moderation policy, they have been accused of leaving in posts that can be “slam-dunked” and deleting a few that they can’t answer (with pointers to peer-reviewed papers). I haven’t seen any proof either way.

    Anyway, I think SPS’s have a part to play in solving the climate issues, not so much because there isn’t technology that could be deployed more cheaply, but because every one plants the human footprint on the environment, just in another place. Ultimately, the safest and best thing is to lighten the terrestrial footprint as much as possible, which means not just power generation in space, but ultimately most industry and even bulk farming.


  25. Art, I still wouldn’t rule out the ‘reflector’ approach as I don’t think we
    should be rectifying and re-generating microwaves, which would add losses,
    complexity and weight. Remember that microwaves behave rather like light, and
    you can build different simulated materials (conductors, dielectrics, …) as
    three-dimensional arrays of large numbers of differently-tuned dipoles.
    Such structures would be very ’empty’ and light.

    Alteratively, just space-grade chicken mesh on an ultralight carrier frame…
    you will need adaptive optics to focus the beam. This has been done for light,
    and for microwaves it would be easier esp. in microgravity.

    Yes, having a phased array on the high seas is a bit of a challenge.

    Yes, the tone on RC is unimaginative, and that’s OK for the site. And as I said
    earlier, I believe there are many options which are affordable and realistic,
    but just don’t get considered because — well, they don’t get considered, and
    not for technical reasons. This thermal solar thing is just one example.

    It’s the same with the denial, it’s not about the science, it’s about vested
    interests. That’s why debating is usually senseless. A resource like RC is
    priceless however to point to in an environment where the deniers have the
    means to put a blanket of noise over everything, so ordinary citizens have no
    hope of forming a balanced picture of how things really are. (Heck, I am a
    geo-scientist and until half a year ago when a discussion on an unrelated list
    prompted me to start digging, I still took things like the MWP and solar
    forcing seriously, as well as claims that there was something fishy with the
    “hockey stick”. With my physics background, I mostly figured things out on my
    own without RC but have been hugely happy to find it.)

    This is also the reason why I am not entirely happy with their moderation
    policy. They are leaning over backward, perhaps in the vain hope of not being
    accused of censorship. It has worked reasonably, but the comments would be a
    better resource with more aggressive weeding of — well, noise ;-)

    – Martin

  26. It actually sounds pretty realistic, Martin, remembering that you now need phased array antennas on the ground. You wouldn’t be able to reflect it, you’d have to receive it and re-beam to another location. Given a smart orbital antenna made up of smart elements, I’d assume this would be feasible. Also, it should be possible to beam power to many sites simultaneously, rather than just one at a time.

    Such things should be tried out, however, before being build into plans.

    You may have noticed the general tone at RC is sort of un-visionary, that is any technology that isn’t already in production, and some that is, gets shot at from many directions.

    I don’t have a problem with that, and I admit that the concentrating solar option is looking pretty darn good technically, which I wouldn’t have known if I hadn’t jumped in with the SPS option. Still, I think that they should be more open to our civilization’s capacity for solving technical problems.

    Don’t forget, either we need a major project to access Lunar materials, or we need a quantum jump in launch technology.


  27. AK, I see your point. However, I feel that not building some sort of habitat in free space may be the same kind of mistake as not considering the use of off-Earth raw materials. It looks like a detour, but really it’s a shortcut :-)

    As for space power in general, I don’t consider myself an ‘advocate’, but I detest not even considering the option, our current technology pessimism. There are many techniques for carbon-emission-free energy generation also on Earth, which are only a little bit more expensive than digging/pumping up fuel and burning it. The problem is political, the unwillingness to face even well-affordable cost hits, and the existence of commercial interests able and willing to fund a large ecosystem of FUD-generating denialism.

    BTW the biggest advantage of space-based energy could well be not in the generation but in the distribution: those microwave beams are very easy to switch to any point on the Earth surface where a rectenna array is located, like close to major population centres. You could do away with many high-voltage lines polluting the landscape (actually, being linear, much more so than the rectennas would).

    This relates to another idea I have had: OTEC (ocean thermal energy) plants floating on the high ocean, relaying their energy over geostationary reflectors. This would directly exploit the above advantage, allow free location of the plants and solve the transport problem. And the reflectors could be a lot lighter than full-fledged powersats… how realistic does this sound?

  28. Martin, I had to select a scenario for use explaining to people more familiar with climate issues than space technology. I want to show them that there’s nothing “outlandish” about the Lunar material thesis when you look at it.

    O’Neill’s scenario included habitats, thus robotic factories could be run by people nearby. But if you’re not going to have habitats at L5, it’s better to put your factories in GEO, where they can be controlled by people on the surface. After all, it’s a lot cheaper to hire an expert robot supervisor on earth (anywhere on earth), than to train them and send them into space.

    I’m also assuming that with solar panels, ion engines, and a little sodium, it will be possible for an unmanned object to find its way around the Earth/Moon system. All this because of the advances in micro-electronics.

    I’m also not so sure that manufacturing is easier in space than on the Moon. You still have access to hard vacuum, and don’t have to plan out every expansion of living area carefully the way you’d have to do at L5. (Because of the need to allocate shipping to lunar dust for radiation insulation. All you’d need is a shovel.)

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