Space-Based Solar Power

a public discussion sponsored by the Space Frontier Foundation

Space Solar Power Demo: WWWWW & H?

Posted by Coyote on January 12, 2008

It’s time to get busy again!

Our very good friend, Hu Davis, recently circulated some good questions regarding the who, what, when, where, why, and hows of demonstrating space solar power. He poses the questions from the perspectives of two groups; space solar power enthusiasts, and some NASA people who work the International Space Station (ISS). (Please note that like the rest of us, our friends at NASA-ISS are just brainstorming with us to see what help the ISS might be able to lend to advance space solar power concepts–there is no official NASA position or policy on any of this yet.)

Below you will find the questions posed by Hu. Please comment!

From the SBPS crowd:

1. What should be the content, scope and cost of an updated systems study to re-examine the cost effectiveness of a full scale network of 5 to 10 GWe satellites and their necessary space and ground systems? There are many subordinate questions not yet answered, including how to pay for it and who should run it.

2. What should be early, low cost (< $100 Millions total) demonstrations? By whom? When? Source of funds?

3. What should be demonstrated at higher cost, but costing much less (10-20% of that of a full scale prototype)? Sequence? Timing? Cost? Whose money?

4. How should we address the “space infra-structure” matter? When? Who? In what order? Time and costs?

5. What will the full scale prototype be? When can it become operational? Schedule? Cost? Barriers?

From the ISS bunch:

1. What can the ISS support? Power / time? Suspended mass? Torques? Dimensions of test articles? Pointing? RMS usage? EVA? Expected end date of availability? We need an “ISS User’s Guide” for space power development.

Thanks! Coyote


96 Responses to “Space Solar Power Demo: WWWWW & H?”

  1. Des Emery said

    Hi, Coyote — It seems that the only question that Hu didn’t mention is the time constraint. The previous blogs appear to have also ignored that aspect of the “problem.” Your own comments raised the issue, even if somewhat reluctantly. But global warming is real and it is imminent and its repercussions could change international stability in ways we cannot predict.

    Its threat to Solar Power lies in the fact that its effects on civilization will be more of a catastrophe than incoming asteroids, for instance, and will divert attention from what could be done in developing a secure and relatively cheap source of electricity into immediate actions to mitigate the disasters you foresee, unless solar power can be harnessed without the bureaucratic and developmental delays typically common in establishing a novel technology.

  2. Dan Lantz said

    “Full scale” network of 10 GWe satellites, given 20 TWe needs, is 2,000 satellites! Don’t make plans that have to be radically changed to grow large enuf to be interesting to global problem-solvers.
    Demonstrate ability to relay energy thru atmosphere by sending from existing Earth grid to military bases, via relay satellite. One can easily see that it is possible to collect the energy in Space, but that is also bigger satellite(s), or done on Moon.
    Start sending energy collected on Moon thru earlier demonstration relay sats. Demonstrate manufacture of some components from lunar resource. Try to learn how to minimize launch cost bottleneck.
    Don’t make the glaring mistake made in this article:
    where the main point of ISRU (“In Space Resource Use”) is totally missed. ISRU is a generally useful, exponentially expandable and start-as-soon-as-possible concept. Requiring justification of ISRU from a single project is like requiring a road to be justified by EACH car trip that would use it.
    “Full Scale” would seem to be where the transmitter is of some optimal size (based on rectenna design?), limited by how much load it can send, thus needing to be duplicated. How big is this, geosync and Moon?
    ISS 1):
    Power ISS from ground grid as part of 2) above demo, perhaps using relay sats.
    #1 Des Emery:
    It seems obvious that any sizable Space project MUST use Space resources for the simple, heavy parts. Launch costs! The only way to do this is to START! Only experience over time will lead to success. It is the hard, but needed step. The earlier we start, the more we will learn. Launching “stuff” (other than pure research or demo) is a waste of time if we already know that it has to be made with ISRU process to scale up.

  3. Des Emery said

    Dan Lantz — I’m with you! If the project is all talk and no action what’s the point? The sooner that ‘parts’ are proven by demonstration, even if by model only instead of with full-scale experiments, the sooner consolidation could be accomplished. The time for adjustments, comparisons, and justifications is after real-time launch.

  4. Edawg said

    ISRU would be great for SSP but the tools do not exist to harvest the resources!I did hear a rumor that Catipillar was looking to develop some equipment for lunar ISRU??

  5. Neil Cox said

    There are some engineering problems with a ten billion watt SSP that are unimportant in the megawatt size. 1. Let’s suppose we connect the solar cells in series-parallel so they produce ten million volts at 2000 amps. The voltage nearly doubles if the current is reduced to zero by disconnecting the load. How do you design a switch which will open at 17 million volts? High explosives that vaporize several hundred meters of the power line will likely stop the flow in a few seconds. In the high vacuum of space, the plasma will disapate quickly extinguishing the arc. 2 We have limited experience at sea level pressure up to about 2 million volts. We think it will be easier in the very high vacuum of space, but I don’t think we have tested even 1/2 million volts in space.
    3 We have lots of experience with 2000 amps or more, so we know it takes tons of copper even for short distances and as much as 50% resistance losses.
    4 How big is a 20gigawatt photovoltaic array? At 500 watts output per square meter (currently optimistic as 1376 watts of sunlight are available near Earth) 40 square kilometers are needed; 40 billion separate photovoltaic cells at 1/2 watt each. perhaps 50 billion connecting wires (most less than a centimeter long) for the series parallel array. We do need some big massive conductors to get the power to the 40 billion laser diodes or thousands of klytrons. The transmitting array needs to be several kilometers from the photovoltac array otherwise the photovoltaic array will occasionally be shaded and the beam will occasionally hit the photovoltaic array instead of Earth. I suggest connecting them with a long flexable power cord.
    5 A shorted cell, diode or klystron only causes a minor power loss, but an open can produce severe arcing (due to the very high voltage)which is likely to damage adjacent devices. How do we replace bad components without shutting off the ten million volts? If we have about an hour to shut off the ten million volts, we can rotate the 40 square kilometer photovoltaic panel until it faces away from the sun. Faster rotation will stress the array mechanically, unless the structure is made much stronger and thus more mass than is otherwise needed.
    6 There are about a dozen places in the system where power is lost, besides the copper losses, so 20 gigawatts at the photovoltaic cells likely is not enough to put 10 gigawatts on the grid next to the rectenna nor a laser energy receiving site. It may be more efficient to build 1/2 gigawatt SSP satellites than ten gigawatt SSP. It appears that ecconomy of large scale fails above about 1/2 gigawatt. I think there are also problems with concentrating mirrors and steam turbines above about 1/2 gigawatt, but these alternatives may be a bit better for very large scale. Neil

  6. Neil Cox said

    While I agree we likely will never get a terrawatt from space, without using asteroid and/or moon resources, it will likely be 2040 or later before we can get even one gigawatt worth of material in space, by any and all means. A terrawatt is one thousand gigawatts or one trillion watts. Society may collapse long before 2040, so we need to do what we can in the next year or two. We can increase funds supporting research such as, CNT, laser launch systems, concentrating space mirrors, tether researh, giant high altitude ballons, the Lantz redirect phased arrays, and pilot model SSP as soon as we get our act together. Neil

  7. marlon facey said

    My following statements may not be what every on this website will want to hear. The problem is not lack of supply of energy; the problem is that we are demanding to much.
    The engineering problems at hand are to make all aspects of energy consumption more and more efficient. The Energy than is being use should come from environmentally safe and also be sustainable.

    The fact that we are always seeking a magic bullet (earth/space based fusion power) will not have the short/medium and long term impacts that will reduce global warming.

    NOTE: Earth base fusion power has to over come fundamental scientific hurdles, whilst SBSP has huge commercial, and governmental hurdles.

    The effects of global warming are already being felt all over the world. It is time for the human race to step up to the plate.
    If the solutions are to be provided by science, industry, government and commerce
    your attention needs to be focused on demand management and energy efficient consumption.
    The consumer is at the heart of all this since it is our way of life that has to be re-moulded. There are profits (an political capital) to be made by issuing in the creation off green technologies and economies (a second industrial revolution if you like).

  8. Dan Lantz said

    #6 Neil:

    I’m certainly not opposed to research, but we need to work on a plan that will scale up to some globally meaningful size. Otherwise we contribute to the global problem(s) by diverting interest(attention)/resource from similar projects that would scale up. Citing as a problem the lack of lunar factories is a step in the right direction, compared to thinking the whole concept ridiculous. Now it is time to go ahead and send some “starter kits” up, and learn how to do it. Once you realize ISRU is needed, and that the longer you have to work on it, the better/sooner the results will be, it seems a distraction to launch product rather than factories to make such product. Imagine the ISS having been built by adding things to a big, simple glass or metal pressure/truss structure made with ISRU? Imagine the SAME factories making the Mars vessels’ basic structure in a similar way. Support structures for SPS both in orbit and on lunar surface then made by SAME factories. The bulk of the solar collectors and relay sats. Just keep on doin’ it! Society will be much more likely to collapse if we don’t do this. ASAP.

  9. Wolf said

    I am fascinated to have stumbled upon this website. I work in cleantech venture capital as a technical due diligence consultant ( analysing the technical merits of various cleantech proposals ) and analyse investments mostly in solar power.

    By commercial criteria for investment ( ie business, technical viability and safety risks), I sense too many real issues relevant to the safety of this proposal (PV power generated in space and beamed down via microwaves to earth ) and its competitiveness to alternative terestrial solutions for solar based power, are seemingly glossed over in discussions here.

    In the past year I have reviewed some 50+ cleantech power and storage startup proposals and this would never make the cut for commercial grid scale power deployment due to profuse risks that are not per se technical challenges, but safety risks that cannot be mitigated ( and are not discussed here in any real depth here it seems, just calculated away and not examined in any real depth ).

    In the case of the needs of the DOD, there are reasons why there is an imperative to have this capability for DOD requirements that are obvious in emergencies and battle, but this should never be deployed nor considered to be deployed except for emergencies, and never for general grid scale applications for electrical power generation. If one cannot see this, I dare say one’s ability to assess risks is a tad weak to say the least, being polite. If you are unfamiliar with the physiological and biological risks from microwave exposure, just take some living cells and examine what happens to the DNA in subthermalizing microwave exposure. Easy to do with atomic force microscopy, and the results to the naive ( many here ) will be startling, if one understands biology.

    Moreover, glossed over here, is despite the terrestrial risks that are both obvious and glossed over, is that there are profuse risks to satellites in orbit that I dare say has not been discussed in any material manner. Again in battle this technology can be rationalized if there are priorities on a temporary basis, but for near continuous terrestrial grid scale application I seriously call this whole concept into question.

    I think it important for transparency, that despite there being a DOD office to study this, that at the masthead of this website, the prime contractors pushing for this, need to identify themselves, as some of the discussions seem to be strangely self serving, to be polite about it. And the parties who work for the contractors proposing this, who post here need to identify their affiliations, as this is potentially involving taxpayer money of significance. This is not funny.

    And other discussions seem to be from folks who are impractically enamored of technology for technology’s sake, devoid of any real world perspective. One can calculate to the moon so to speak to justify just about anything, but if you do not have any ability to see the potential risks ( glossed over as if the systems safety is some black box ), you are not a responsible designer.

    The counterpoint of the propsal’s impractical technical aspects – costs and safety and any real world justification for near permanent deployment for large grid scale application, is that any kind of “conventional” terrestrial concentrating solar thermal power, generating terrestrial electricity for connection to the grid, is both very cost effective NOW, cost competitive NOW with best in class cheapest grid scale power ( including Coal, Nuclear and even Hydropower ) and the only thing slowing the justified rapid deployment of same (CSTP), is that the bulk of the concentrating solar thermal power farms need to be in the far southwest lower 48 / southeastern California, and to maximize the generation of this kind power electrical power for national grid scale, one best build out high voltage DC power lines of very high capacity ( ie fractional grid scale ) and >500KV across the country, and build large scale power buffering / storage. None of these requirements are at all arduous nor impractical, and all are justifiable far more easily than any hypotheticals discussed here, at least for non DOD applications.

    CSTP will not entirely displace the present grid generation, nor should it, as different power generation means have different technical and application strengths, but certainly concentrating solar thermal power needs to be the preponderance of clean power generation buildout in the foreseeable future, for a whole host of reasons tat are obvious and I will not go into here.

    I’d be curious as to a truly open debate of the real technical merits and costs, where even terrestrial solar photovoltaic power of any kind ( without having the challenge of being space based with all the attendant costs in that, nevermind technical and safety complications of space based deployment described herein ) is well known to not be cost competitive with present grid scale power and is unlikely to ever be, and by contrast CSTP is well known by experts to easily attain grid scale baseload cost parity with technologies known today.

    I will emphasize that the well known solar troughs concentrators – with costly shaped glass parabolic mirrors are no longer state of the art in CSTP, and I will not go into depths of the technical descriptions of what constitutes state of the art for low cost grid scale CSTP, but suffice to say it exists, and is slowly gaining ground for future larger deployment.

    Yours Truly, Wolf

  10. Dan Lantz said

    Wolf #9:

    “If you are unfamiliar with the physiological and biological risks from microwave exposure, just take some living cells and examine what happens to the DNA in subthermalizing microwave exposure. Easy to do with atomic force microscopy, and the results to the naive ( many here ) will be startling, if one understands biology.”

    As I have said in the past, the biggest problem facing SSP is the fear of microwaves. I have no opinion on the matter, as opinions on testable claims are a waste of time!

    “Moreover, glossed over here, is despite the terrestrial risks that are both obvious and glossed over, is that there are profuse risks to satellites in orbit that I dare say has not been discussed in any material manner.”

    This leads to only one of the advantages of Lunar Solar Power over Solar Power Satellites.

    “One can calculate to the moon so to speak to justify just about anything, but if you do not have any ability to see the potential risks ( glossed over as if the systems safety is some black box ), you are not a responsible designer.”

    Designing a way to get industry and population off the planet is entirely responsible, thank you! The risks of not doing so ASAP are deadly, for the biosphere and, in a more immediate way, humans.

    Check out references in #2 above for costs, realizing that you need to “think globally”.

    Thanx for input!

  11. Wolf said

    the other technical issue relevant for viability to near permanent use for grid scale terrestrial power is the likely strong susceptibility of this technology to damage by solar flare activity. This is separate from the safety concerns.

    For certain in the microwave beaming method, there is likely to be a huge propensity to possibly massive surge induction at receiver and generator by solar flare ionization(plasmas) that is is unclear how to protect against (especially given the scales hoped for ).

    In the microwave case, the whole beam is a current displacement? and microwaves are well known to ionize gases ( ie form a plasma of their own ) under the right conditions. The length of the beam from satellite to ground will make this a kind of antenna for “capturing” solar flares, and the damage to the system will likely be considerable if no practical means is found to protect against the surges associated with solar flares.

    Moreover, I think it is the NOAA that is indicating the strong possibility of us just starting to enter a ~12year period of increased solar flare activity, surmised by some observations in Sun activity pattern, observed just recently.

  12. 3seagull said

    Alright Wolf, give it a rest.

  13. Neil Cox said

    Hi Wolf 9 and 11: Of course there are safety concerns. This is likely why the SSP = space solar power analysis of 10 or more years ago suggested 400 watts per square meter = 0.4 milliwatts per square millimeter for the beam at the rectenna. This does not thermalize significantly, except DNA will behave like a receiving antenna at certain frequencies. These frequencies can be avoided, if you can tell us what they are and the milliwatts per square millimeter that does not disrupt DNA at the least damaging frequencies.
    As you suggested, higher energy density is needed for military applications. Sooner or later there will be injuries. But injuries and deaths are occuring now because we do not yet have this technology.
    Apparently the studies were done long ago, as the FCC = Federal Communications Commission mandates maximum allowed exposure. We should not exceed these power densities for commercial power, unless rather extreme measures are taken to assure humans are not exposed. We do need to take some risk as civilization may not survive, unless we develop this technology or equivalent which may be even more risky.
    The satellites in low Earth orbit will be exposed to about 0.4 milliwatts per square millimeter, from SSP in higher orbits, perhaps one milliwatt per square millimeter, if the SSP is at an altitude of 300 to 600 kilometers. If the satellites are not already protected from this EMP = electromagnetic pulse level, they can be protected.
    Our lack of conscern is partly because we are still very early in the analysis and engineering study of SSP. In my opinion, more studies are needed and some small scale prototypes and simulations on Earth’s surface and from balloon platforms.
    We can do moon manufacturing studies at the same time as SSP, but I think this should be a separate effort, as the technology is likely even less advanced than SSP technology. I don’t think we will soon know where either is likely to go, so we should not assume finnished goods nor even raw materials will be available in space even for the hundredth SSP that we commplete.
    As far as I know there are no prime contractors pushing for SSP nor Moon manufacturing. As for myself, I have no affiliations and don’t expect any compesation for my sugestions. I agree terrestral solar, wind and several other alternatives are presently less costly than SSP, but that will be true forever unless we begin the process of developing SSP.
    We have had assets in space for 1/2 century, with few failures from solar flares or CME = coronal mass ejections, so my guess is more advanced protection than many other details. Terrestral power lines transpose the lines at 100 meter or oftener intervals, to reduce valnerability to EMP. It may be necessary to transpose parts of the solar array, at one meter intervals to get high protection from EMP. If so, this could double the copper weight.
    HAARP is studing the effects of very strong signals in the atmosphere. As far as I know the HAARP beams have not behaved as conduits for solar flare ionization nor lightening strikes. Likely DoD can gain access to the HAARP data.
    Several 12 year cycles will likely come and go before we build the first gigawatt beam. If that causes a problem, we may need to build thousands of half gigawatt SSP instead of hundreds of ten gigawatt SSPs. Neil

  14. AFAIK the FCC does not regulate maximum human exposure to microwaves. FCC regulates interference between radio systems. To my knowledge here is no agency in the USA which regulates human exposure to microwaves in general. The FDA (Food and Drug Administration) enforces a standard of 5 mW / cm^2 for microwave oven leakage, it is unclear whether this standard can be legally applied to other applications. There are various ANSI and military standards governing human exposure, which are usually applied by contract, but are not otherwise generally enforceable across the board. I would appreciate more insight from anybody on this.

  15. Neil Cox said

    FCC rules for amateur radio operators are rather detailed with lower intensity for some frequencies around 200 megahertz. I don’t know if this applies to commercial broadcasting. The international standard for microwave ovens is 20 times the number you mentoned = 0.1 watts per square cm. This is 1000 watts per square meter or one billion watts per square kilometer, but I don’t think anyone responsible has claimed that these scale ups are completely safe, even though many people have survived higher exposure levels for many hours.
    I suppose a big pile of money needs to be spent to determine the level at which various frequencies cause one additional death per million people. We did this for ionizing radiation, but experts still have a wide variety of opinions on how much middle gamma causes how many extra deaths. Neil

  16. charlesshults said

    I can see many solutions to some of the problems that have been posed. First, like any good system, this should be a modular concept. Even very large power collectors should be designed to be essentially self-sufficient. This gives multiple redundancy at the outset.

    Now, a need to expand the capability means simply adding more modules. As a benefit, the modules themselves are smaller and sidestep many problems that a single large-scale system may present.

    Another item that arises time and again is that of launch costs. I know that serious study was done in the early 1970s by the Navy on making factory modules that, once launched and emplaced, would produce the components needed for the construction of a solar power system. This means that we do not have to launch huge quantities of hardware and also face the environmental problems that a large number of launches deom Earth might incur.

    So to me, it seems reasonable to have an effort aimed at recovering lunar resources to make the power station components and then launch them to a catcher station- not a new idea, but one that seems to escape many critics. And the critics are a real problem (and resource) when dealing with new technologies or ideas.

    So we can get around the technical issues of a very large scale solar SSP system and we can eliminate a huge portion of the launch hardware and costs with two simple ideas. Of course, comments are welcome.

  17. Andrew said

    What about making an XPrize competition for these concepts? I know the Ansari Foundation is looking for new ideas…

  18. Chris said

    Hi Wolf. What are your affiliations?

  19. Dan Lantz said

    #16 Charlesshults:

    Good overview. Please see
    for “next” step in logic.

    #17 Andrew:

    How about prize/auction of first manufactured “trinkets” made from lunar resource, returned to Earth?

  20. Neil, according to FCC rules, there is NO UPPER LIMIT to the power which may be radiated in ISM bands. Those are the bands which will be used for power beaming.

    The FCC only regulates power levels outisde of the ISM bands.

    I have yet to identify any US federal agency which regulates general public human exposure to ISM band radiation, apart from the FDA limit on 2.45 GHz microwave oven leakage, which occupies only one of numerous ISM bands at various frequencies.

  21. Here is an FCC standard which is entitled “Guidelines” but which might be legally enforceable to both controlled and uncontrolled situations involving the general public:

    OET Bulletin No. 65 (August 1997)

    Evaluating Compliance With FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields

  22. Edawg said

    I know I complain alought about this issue but mark my words ,if we do not plan on using NTR rockets or a eelv/HLV you can kiss SSP goodbye along with humanities chances for survival.Free market can solve many problems regarding constuction but the proper tools need to exist for the free market to utilize.

  23. cfrjlr said

    The FCC limits for human exposure are presented in OET Bulletin 65, Table-1, for example, for frequency range 1.5 GHz to 100 GHz:

    Controlled exposure: 5 mW/cm^2 averaged over 6 minutes

    Uncontrolled exposure: 1 mW/cm^2 averaged over 30 minutes

  24. Des Emery said

    My “affiliations” are non-existent, but my age makes me eager to see progress in such a project as this one is. I have watched world problems, both natural and man-made, leap forward at an exponential rate which threatens us all.

    Cheap energy in volume is one solution I see, but “volume” is much more important than “cheap” when mankind’s survival is at stake. When steam engines and automobiles were being developed speeds of over 30 mph were considered “too dangerous” for our bodies to withstand. Well, we did survive, but the same argument was raised after WW11, worrying what awful thing could happen to us at supersonic speeds.

    Wolf is right in raising concerns, but he needs to look beyond the present and its restrictions and help to figure out how we can succeed in reaching for the Moon and touching space.

  25. Wolf said

    for the folks who are skeptics regarding the cancer risks of small field microwave exposure please read this

    This is a landmark study well conceived.

  26. Wolf said


    There ought to be a Mars program, even MUST be a Mars program and a Moon program. Space exploration is among man’s more noble quests and is admirable and substantively significant in many many ways.

    “Wolf is right in raising concerns, but he needs to look beyond the present and its restrictions and help to figure out how we can succeed in reaching for the Moon and touching space.”

    My concerns about SSP relate to attempts to link it to terrestrial grid scale power generation, which I obviously take issue with to put it kindly. SSP is needed for space exploration and establishing colonies on the moon or mars and for long distance human space travel. And for defense it is an imperative. Absolute imperative for defense, as one cannot get caught with one’s pants down in arms technology, where SSP is a platform enabler.

    But for terrestrial grid scale power, I think SSP is wrong largely due to a whole gamut of safety and COST issues not encountered in the slightest with CSTP.

  27. Dan Lantz said

    Wolf #25:

    Good study. Shows that cell phones are dangerous, or that talking a lot is dangerous! Stress at salivary gland when talking is obvious. Remember when it was claimed that power lines’ radiation/fields were dangerous? Only when clusters of overly cancer free people living near lines were included in the numbers was it seen that the clustering of cancers found was totally random. This should have been suspected from the fact that the initial clusters found were of different types of cancer. When large numbers are already “experimenting” with a risk factor, it will always be easy to find preliminary clusters of possible effects (perhaps good effects). It will also be easy to see/prove any ACTUAL measurable effects. The perfect set-up for skepticism! Let the truth of the matter be determined.
    Also, consider the dangers of NOT leaving the planet, or NOT removing energy collection and mining from the planet. Requiring perfect safety in any solution will cause NO problems to be solved, no matter how dangerous the initial problems are.

  28. Neil Cox said

    The link tells of cellphone induced cancers. This may indicate that SSP is less of a hazard. The average exposure from a cell phone in use may be 0.1 watts per square cm = the max allowable leakage from a microwave oven. Microwave oven users however are typically about one meter from the microwave compared to about one centimeter from the cell phone. In theory the 100 times farther means 10,000 times less exposure. There are many complications, so the micro wave oven may be ten times safer than the cell phone, per minute of use. Heavy cellphone users are typically exposed ten times as long per day as heavy microwave oven users. I’m concluding the microwave oven is typically 100 times safer than the cell phone. Humans will typically be in the SSP beam one second per hour, compared to 100 seconds per hour for the heavy user of a micro wave oven; so the beam exposure is 100 times safer than the micro wave oven = 10,000 times safer than the heavy cell phone user. Part of this advantage is negated due to whole body exposure to the SSP beam compared to part body exposure to the microwave oven and cellphone. Frequency also makes a difference. Likely visable light from lasers is less hazardous than most microwave frequencies at 0.1 watt per square centimeter, which in my opinion is acceptable (perhaps negligible) risk. More studies should be done when we have determined the frequency and other details. Neil

  29. Kasei said

    some numbers: 1mW/cm^2 (FCC standart by #23) means 10W/m^2 where normal solar cells collects far more energy per square meter(around 50-100W/m^2).-> 1GW rectenna will need 100 km^2.(too huge IMHO, so we need higher intensities 10-100mW/cm^2 or 100 W/m^2 to 1000 W/m^2)

    Under a microwave rectenna there is of course a much smaller intensity as in the air above. if it converts 90% only 10% reach the space below, so if you radiate with 10mW, below will only be 1mW. so only birds will suffer some higher intensity. and because light shines through microwave rectennas, you can grow things below, some biomasses that you can use to make biofuels, so nobody has to fear to eat some radiated corn or something.

    so like neil said, if frequency is determinded make some studies, how living beings react to different intensities of such radiation. Like does grass or corn or wheat grow under constant radiation etc.

    to what can the iss do? the ISS is to date the largest sturcture in space with the most power. so get some mircowave transmitter up there and start messuring the atmosphere absorbtion of microwaves. ( are there some studies to find some numbers for 2,4 or 5,8 GHz? i found that form 1968: but it discuss 10-100GHz)

  30. Neil Cox said

    cfrcij post 23 may be correct, but I agree we need a waiver for SSP allowing much higher beam desities where reasonable precautions are taken to protect humans. Protective clothing (needs to be developed) may be sufficient protection to 5 watts per centimeter squared = 50 kilowatts per square meter, which would be sufficient for high performance vehicles. I don’t think we can get this high a power density from GEO altitude even with millimeter waves and a two kilometer transmitting antenna. With visable light from diode lasers with fancy optics, that high a beam density is likely possible, but controlling (plus or minus one meter) the illuminated spot will be very costly from GEO, but likely off the shelf from closer locations for the SSP in my opinion.
    My guess is one kilowatt per square meter will shorten the life expectancy of average birds by less than one day. 50 kilowatts per square meter will be deadly to birds, but my belief is we should approve up to this density when human lives are likely to be saved. Neil

  31. Wolf said

    for the folks here who are making technically incorrect conclusions ( not merely prematurely incorrect ) about physiological cancer inducing effects (actual) of microwaves – ie prematurely and wrongly concluding safety is possible – you are out of your field of exoertise and understanding, ( that is polite ). Contact the cancer researcher who authored the cell phone cancer article for expert interpretation of obvious health risks of this proposal. You will get a reality check that your refuse to acknowledge, quite obviously.

    As a comparison, I’d never trust a medical researcher in electrical engineering endeavors, and I’d never trust electrical or systems engineers decisions regarding health risks. Plain and simple. A good number of folks here are deluding themselves into thinking they have any competence in assessing real health risks that involve microwaves. I have described the fundamental DNA damage mechism from subthermal microwaves is real – READ the biological research literature, which it appears many here are handwaving and illiterate about.

    The analogies implied between 60hz power risks and attempting to infer safety conferred in microwave exposure is ill informed to be kind, and that is a fact. The mechanisms with tissue interactions differ vastely betwen relatively benign 60hz and microwaves. If you confuse facts of well known biological effects ( DNA damage by microwaves that is fundamentally different in root cause mechanism than relatvely benign 60hz ) with obfuscation and long winded incorrect “rationale” this is bizarre. Consult researchers in biology who have done appropriate physiological and DNA research and stop writing meaningless incorrect purported logic devoid of reason. The science exists, and I am not referring to statistical analysis – I am referring to DNA physiological experiments.

    here is an excerpt from google scholar hits on the search term ( you can do this search yourselves btw )

    dna damage by microwave exposure

    proving what I know. Who here has read any of these articles??? Who here is familiar with the research and mechanism of DNA denaturing at subthermalizing microwave field intensities? WHO ??? And moreover why do you claim expertise without knowledge of the relevant SCIENTIFIC literature? Why?

    All the obfuscation I read in some ill informed purported logic is from folks unqualified to make the statements of implied safety.

    here are the 1st 10 google scholar hits from the 9,510 records in google scholar ( SCHOLAR )

    Acute low-intensity microwave exposure increases DNA single-strand breaks in rat brain cells
    H Lai, NP Singh – Bioelectromagnetics, 1995 –
    … strand breaks in isolated DNA after acute microwave exposure. … testis of mice given
    repeated exposure to 2450 … or a reduction in the DNA damage repair processes …
    Cited by 227 – Related Articles – Web Search

    DNA Damage in Rat Brain Cells after In Vivo Exposure to 2450 MHz Electromagnetic Radiation and … – all 3 versions »
    RS Malyapa, EW Ahern, C Bi, WL Straube, M LaRegina … – Radiation Research, 1998 – JSTOR
    … nance absorption or enhanced absorption in aqueous DNA after microwave exposure.
    We are not aware of any other study that has reported frank DNA damage after a …
    Cited by 80 – Related Articles – Web Search

    Comment on“Acute low-intensity microwave exposure increases DNA single-strand breaks in rat brain … – all 2 versions »
    GM Williams – Bioelectromagnetics, 1996 –
    … in SSDB immediately after PW exposure, and remained … The presence of SSDB immediately
    after microwave radia- tion … of the processing of DNA damage resulting from …
    Cited by 23 – Related Articles – Web Search

    Single-and double-strand DNA breaks in rat brain cells after acute exposure to radiofrequency … – all 5 versions »
    H Lai – International Journal of Radiation Biology, 1996 –
    … been used extensively in toxicological studies for DNA damage (cf … it is the frequency
    used in microwave ovens and … In our exposure system this intensity gives an …
    Cited by 202 – Related Articles – Web Search

    Measurement of DNA Damage after Exposure to 2450 MHz Electromagnetic Radiation – all 4 versions »
    RS Malyapa, EW Ahern, WL Straube, EG Moros, WF … – Radiation Research, 1997 – JSTOR
    … Two reports by Lai and Singh (13, 14) suggest that the DNA damage they observed
    in the brain after microwave exposure may be due to an indirect effect …
    Cited by 44 – Related Articles – Web Search

    … of DNA Damage and Apoptosis in Molt-4 Cells after In Vitro Exposure to Radiofrequency Radiation – all 7 versions »
    GJ Hook, P Zhang, I Lagroye, L Li, R Higashikubo, … – Radiation Research –
    … fields with frequencies in the microwave range do not have sufficient energy to
    induce DNA damage directly. However, exposure to microwave fields can result in …
    Cited by 42 – Related Articles – Web Search

    DNA Damage and Micronucleus Induction in Human Leukocytes after Acute In Vitro Exposure to a 1.9 GHz … – all 7 versions »
    JP McNamee, PV Bellier, GB Gajda, SM Miller, EP … – Radiation Research –
    … Cytogenetic damage in human lymphocytes following GSMK phase modulated microwave
    exposure. … Primary DNA damage in human blood lymphocytes exposed in vitro to …
    Cited by 48 – Related Articles – Web Search

    Measurement of DNA Damage after Exposure to Electromagnetic Radiation in the Cellular Phone … – all 4 versions »
    RS Malyapa, EW Ahern, WL Straube, EG Moros, WF … – Radiation Research, 1997 – JSTOR
    … (6) described damage to plasmid DNA in aqueous solution requiring the presence of
    copper ions after 2 to 8.75 GHz microwave irradiation at an SAR of …
    Cited by 42 – Related Articles – Web Search

    DNA damage in Molt-4 T-lymphoblastoid cells exposed to cellular telephone radiofrequency fields in … – all 6 versions »
    JL Phillips, O Ivaschuk, T Ishida-Jones, RA Jones, … – Bioelectrochemistry and Bioenergetics, 1998 – Elsevier
    … exposed in vivo to microwave radiation. Second, the iDEN® and TDMA RF signals produced
    generally similar decreases in DNA damage after exposure to SARs of 2.4 …
    Cited by 67 – Related Articles – Web Search

    Measurement of DNA Damage in Mammalian Cells Exposed In Vitro to Radiofrequency Fields at SARs of 3 … – all 8 versions »
    L Li, KS Bisht, I LaGroye, P Zhang, WL Straube, EG … – Radiation Research –
    … Previous reports (3) suggested that 4 h incubation after exposure would enhance
    the expression of DNA damage from a 2-h 2450 MHz microwave exposure. …
    Cited by 33 – Related Articles – Web Search

    I think this is sufficient to get you to rethink the ill thought out wished for safety of terrestrial microwave power beaming, if you are honest scientifically about the risks of what you are proposing.

  32. Neil Cox said

    There may be a minimum power density for the rectenna. A typical dipole has 50 ohms impedance. To produce 0.1 volts the current output needs to be I = E/R = 0.1/50 = 2 milliamps. Watts = IE = 2 times 0.1 = 0.2 milliwatts. If the average dipole receives the energy from one square centimeter (millimeter waves): then one dipole produces 0.1 volts at a power density of 0.2 milliwatts per square centimeter. No rectifier (as in rectenna) is efficient at this low a voltage. About 100 dipoles must be connected in series to get 10 volts, which gets abot 94% efficiency from a common silicon power diode. Diodes are available (but not mass produced) that are efficient at lower voltages, and there are tricks which can produce more voltage at very low power density. I don’t know if it is practical to operate even 5 dipoles in series. The minimum power density for an efficient rectenna increases with the wave length. If we select a short enough wave length such as 860 nanometers (infrared light) we can use 50% efficiency photovoltaic cells which are efficient (I think) at 0.2 milliwatts per square centimeter, plus they produce power from sunlight when the sun is shining.
    If a million square centimeter rectenna is receiving 0.2 watts per square centimeter: 200 kilowatts is received and perhaps 150 kilowatts is put on the grid. If the grid needs 1500 kilowatts, we can increase the beam power density to 2 milliwatts per square centimeter = 20 watts per square meter, which is likely also completely safe. With near term SSPs we may need several SSPs to produce 2 milliwatts per square centimeter on the rectenna. I think you can see the rectenna should be efficient at low beam power densities for standby power, with more beam power being added as needed. Laser diodes and photovoltaic look more attractive for small scale. Neil

  33. Coyote said


    Thanks for so many references. I’ll look into them. Do you propose another broadcast bandwidth to transfer the power from orbit to Earth? For example, would you be satisfied moving the power beam into the near visible or laser ranges?

    Or would you support putting rectennas in very remote areas, such as an uninhabited South Pacific island, and continuing to bring the power down by microwave?

    Also, since these studies reference long-term exposure, would short-term exposure to microwave power broadcast be acceptable as part of providing power to disaster relief or combat operations?


  34. Wolf said


    Thanks for the kind reply, and please forgive me if I was possibly rude.

    The mechanism for DNA damage is acute for EM radio and microwave at short wavelengths – the cellular size scale electrical field gradients in say microwave versus 60hz are vastly larger as one might guess, and is the root cause of the issue – noting that lasers do not seem to generate the same specific “resonances” / destructive absorption seen from high frequency RF and esp microwaves. I suspect that wavelengths comparable to AM band transmission might be safer(maybe even safe), but I cannot tell yet.

    I think for the proposal to do power beaming of some kind, on a pure technical level it will likely need to use short wavelengths of some kind of EM radiation, to localize the thermalizing power. I really do not have any easy solution to what you ask or imply, and still balance safety issues for terrestrial SSP, where the technical challenges balance safety with the requirements for I guess a narrow beam.

    What I am suggesting is that some indepth study with consulting numerous medical (research physicians, cancer experts – experimental like the cell phone paper author and biologists who have authored papers like those listed ) experts on lasers, RF and the like, to talk and learn implications substantively cross discipline.

    The goals of SSP for what is intended to accomplish here, are indeed noble, in every sense of the word and meaning, but key to increasing the rate of substantive learning (in need to balance safety concerns with technical requirements) is exposure to concepts outside of the present team’s expertise?

    Not selective cherry picking of data and facts, but go at consulting many folks and examining the implications of numerous technical options – a goal driven brainstorming incorporating ?medical and safety input from folks who are not project stakeholders?. The process I describe with the extensive use of cross discipline experts consulting with space engineers, might prove fruitful – indeed I hope so.

    And also, means test proposed ideas simply by even consulting with google scholar to see what the article abstracts hint at ( google scholar is a google search option )…And even if you are not an expert – read what you are unfamiliar with to learn more of what you might not have known prior.

    Laser power transmission might be better, but I really do not know the technical issues to be fair (esp different wavelengths, esp safety hazards from stray reflections ), I am merely pointing out that shorter wavelength EM transmission ( high frequency RF to microwaves ) is likely to induce large numbers of cancers at the power levels being contemplated.

    Lost upon some here, is that regulations (cited but true of most regulations for safety ) are in response to testing results, or speculation, and not predictive of new technologies’ safety. That is my point. Might help with liability in the courts, but does not protect public safety in new technologies. Liability is vastly different from safety I’d assume.

    I suspect that low frequency radio waves (comparable to AM band ) are likely to be least dangerous to health but also likely to make the technical challenges of power beaming in a tight beam and concentrated receiver very difficult if not possibly – impossible technically. I am not competent to gage this properly.

    The idea of beaming to some remote region, might be useful, it might be best in a large desert region to minimize risks to humans and animals, but again, terrestrial CSTP is so darn simple ,the Europeans are in early stages of conceptual studies contemplating building huge CSTP power plants south of the mediterranean – say Libya and other countries, and constructing a massive undersea electrical power transmission system to power parts of the European electrical grid.

    We ought to be doing a comparable large scale implementation here in the US, likely installed in the southwest, to power a significant fraction of the US electrical grid ( via CSTP solar with grid scale power transmission line buildout ) Far more useful than SSP for terrestrial applications and few material safety risks latent.

    So can one say – that some form of laser power beaming might work? For terrestrial applications I suspect some emission wavelengths might be safer than others, but I do not know the technical issues say re atmospheric absorption and related matters.

    But part of what I am really trying to say is that the intent of this variant of the proposal to generate a technology for SSP – Space (beaming) Solar Power – the variant intended for terrestrial applications potentially in common powering of the electrical grid, I am very much not in favor of? ( In large part since CSTP is trivial, except for the need to expand the land based grid scale power transmission networks – which is required anyways, even for SSP curiously )

    That being said, the core technology of SSP described must (absolutely must) be developed for space applications, and strategic military purposes, but even then for man based applications in space, there remain issues of safety for the space travelers in beaming microwaves in close proximity to where they might live ( same issue of health and safety even in space )

    Yours Truly,


  35. Des Emery said

    Wolf’s post #34 legitimately raises questions of safety, specifically regarding microwaves. Perhaps the solution would be a separate investigation into what kind of shielding could be developed, either or both for power grid workers and space travellers.

    I’m thinking simplistically I guess, but plain aluminum wrap pieces ‘shield’ food edges in microwave cooking. Will this requirement to provide ‘safety’ features for the SSP project become a ‘spin-off’ benefit of some sort?

    If Wolf can identify a certain dangerous effect, like microwave damage to living tissue, could he not also think of some way to avoid or deflect the consequences?

  36. Wolf said

    Des Emery >

    this is a valid question, with likely a difficult answer for all situations implied as contemplated in this application for terrestrial and human space travel even planet colonization, regarding human safety.

    I do not have an answer to your question, especially for the applicable case of human space travel, where “earth” grounds are unclear to be available. Clearly in some implementation a faraday cage can be constructed, but again there seem to be imperfect internal microwave re-radiation into interior surfaces, that DC faraday cages need not address.

    My guess ( I am not skilled here ) is that the practical solution to your sheilding question if it is possible, will require sort of fundamental research on a scale of a competent PhD thesis or several, due to the technical challenges that are quite substantial for safety. The downside to application to human space travel, is that conceivably one might induce high early cancer rates in the explorers, defeating some of the utopian goals for successful, viable life human travel. Cancer stricken explorers will not be a pretty sight, and their descendents might not be viable in certain cases.

    In the case of space walks, I suspect the potential hazards are severe, and will be far more difficult to remediate safely than for space vehicle or planet based space applications. Yet these alone will be challenging if one wishes to avoid premature cancers from microwave exposures on the scales implied.

    This is indeed very challenging, and is why for purely terrestrial power applications, intended to significantly supplement grid scale power, one needs to clearly accept that CSTP – concentrating solar thermal power is indeed on many levels, not merely those a consequence of evaluating the potential for SSP, but on a larger perspective, CSTP is a superb answer to greenly and safely and cheaply increasing grid scale electrical power.

    Because EV – pure electric vehicles, will indeed become very practical and cost effective in the next few years ( faster than many realize as yet), therefore increasing grid power generating capacity by safe inexpensive scalable means, will address a variety of terrestrial growth and greening needs, nevermind peak oil issues.

    For pure space applications, I suspect for addressing power beaming with safety above that of Microwaves ( a low standard for certain) likely some form of laser power beaming is a decent compromise and avoids what is likely to be a serious technical challenge for “safe”? microwave power beaming in human use.

    Undoubtedly here, I may have upset a few folks hopes, for that I truly apologize, but successful systems engineering must capture far more information than speculative desk side engineering calculations – there are often, as is here, practical issues that are important, than can often be assessed by quick literature searches as to real world implications.

    Look I wish you guys the best of luck, but best look to lasers as a compromise for space travel etc, but avoid even lasers for terrestrial power beaming is my guess, as the safety incidents will be otherwise quite detrimental to your cause in space as peripheral pr damage? It is very important to pursue this for space using lasers and even for airborne and space based weaponry. Very important indeed. Do not confuse a terrestrial and human safety issue with the imperatives for military advances, ahead of the competition. In space based military applications, microwaves are quite likely warranted. Very different issues.

    Best of luck.


  37. Alienthe said

    Some serious accusation regarding competence is being leveled here. I cannot represent all here but I for one have a background in R&D with emphasis on physics with some RF and microwaves technology. Safety is something I do take serious, as does most people who work in labs and plan on surviving.

    While I am no expert in biology I do follow the debate in professional publications regarding RF safety and so far the debate has not been conclusive, and that in spite of long term widespread microwave use.

    Where I live it is quite common to carry your cell phone in the belt and considering male anatomy this means the RF source is so close to the testicles that any serious danger would have meant mass sterility since 1995. That scenario has not exactly materialised.

    Secondly RF engineers have been examined and it is known that many used to stand in the RF beam to relieve the cold or just to warm their hands in cold climates. Again no widespread problems have been reported other than in unusual cases.

    Some extreme cases are where thermal effect has been too high. Also it is known that high power RF quickly causes male sterility.

    Regarding AM band RF transmissions I know of sites where the local population is monitored in terms of health but again no systematic effects have been observed.

    RF does have other problems such as the need for allocating a band, the public fear of invisible power along with perceived weapons potential, complexities, conversion efficiencies and more.

    Personally I am a proponent of using visible light as transmission power since it is not regulated, visible in a rather obvious fashion, the light can be useful as is (illumination, pumping energy into photosynthesizing algae etc) as well as convertible using tried and tested technology in the form of solid state solar cells.

  38. Wolf said

    Dear Alien_the,

    I am not saying people here are not credentialed. I am indicating that many of the premature conclusions regarding (hoped for) safety are ill founded, and FCC regulations in a new application are not a sufficient guideline in the slightest in new areas. Yes FCC standards might form the basis for liability defenses, but has no bearing on real intrinsic safety with respect to cancer incidences for new applications. Besides which cancer studies have to deal with the latency delays from cancer onset to clinical cancer. Large difference between initial DNA damage and when one is clinically classified as having cancer. Large latency in most cases of any cancer cause, and not the specialty of the FCC.

    Regarding the belt wearing of cell phones, the linked study answers some of the questions you have. Some types of tissue are more susceptible to microwaves. Some cell phones emit less power, some cell coverage regions force cell transmissions at higher power, and so on. And standby conditions on a belt are less exposure dosing for localized tissue for certain than holding a phone next to ones face to talk with higher power and duty cycle in microwave emission?

    Belt wearing of cell phones likely results in considerable change of position of peak power adsorption (never mind the large duty cycle reduction in pulsed power during standby cell site pinging versus transmission when held at one’s face), and reduced risks in many instances. Again tissue type exposed at peak powers ( versus quiescent standby in your belt ) likely has some impact in low intensity sources like a cell phone.

    The scale of what is being contemplated for energy beaming dwarfs any cell phone exposure by huge amounts, if accidents occurred. And for long term exposure by folks adjacent to the receivers there is good reason for caution, sensible caution, as opposed to position statements or speculative optimistic calculations that are unfounded as to real safety risks for the oft forgetten statistical “tail”..

    Sweeping statements (even calculations) – generalizations, are not useful in assessing real risks in novel applications. One has to assess worst cases and intermediate conditions that are not comparable to wearing a cell phone idling at low power & tiny transmission duty cycle on a belt, or operating a cell phone in areas of good signal strength ( lowering your cell phone’s need to increase emitted power output )

    I will also point out that too often folks with strong academic credentials in one area / discipline take unwarranted license as to their skills in other fields that may not be realistic ( unless they reads the literature extensively in the new areas ).

    Authority comes from relevant work or sufficient reading in the specific area – here Biology of Cancer. But even granted that, you make sweeping assumptions that are wrong in the physics (dosing of belt wearing versus talk time etc.), so I am unlikely to trust your conclusions with my family’s safety ever. And I doubt you’d volunteer to live adjacent to an SSP microwave receiver either( even at the minmum safe distance), which is another means test of practical note.

    You will likely take offense to this, but go read the articles on DNA damage by microwaves you seem to pass by ignoring as some (many?) do here. The cellular scale EM field gradient effects ( implicit mechanism of short wavelengths of microwave / high frequency RF enhancement of DNA damage ) are characteristic of a particular range of shortwave / microwave EM radiation, increasing the peak absorption in tissue and particularly DNA.

    This issue is of interest here as many EEs and physicists (I am a physicist btw) think that only radiation of a nuclear kind causes DNA damage – which is patently wrong on many levels. Not a cell phone belt premature conclusion, but physiology based interaction with cellular matter.

    A cell phone on the belt irradiates large masses of muscle and fat at repeatedly different locations, in standby power of low power duty cycle. That is not what might be encountered in Grid Scale Microwave power beaming accidents or “stray” exposure. Simple question to ask is can cancer be initiated in fat tissue? Not as likely as in muscle or other functional tissues. Not by far for certain. Have you heard of any cases of folks being treated for fatty tissue tumors?

    Does one need a PhD in physics to comprehend thesematters? (my apologies if you miss that difference, but it is experimental and not theoretical) Pretty simple stuff you seem to not grasp, nor wish to contemplate or acknowledge the differences in experimental conditions.

    I’d encourage you to do considerable more reading in Microwave damage of DNA and contemplating what your learn in the context of what is being proposed here.

    Given the newness of this topic there is considerable subtlety in experimental conditions that bears reflecting on likely worst case near 100% duty cycle microwave terrestrial power beaming, that goes far beyond any cell phone belt analogy in dosing and peak intensities in use and accident.

    My apologies to you fpr jumping to overly simplistic and premature conclusions, but reality of experimental conditions and physiological effects are salient matters in this discussion, and not one’s credentials of technical authority from outside this technical area of cancer and its causes from Microwaves – DNA damage by microwaves.

    As to the example you cited regarding testicular cancers from wearing one’s cell phones on a belt, the well known study (~1980’s) of microwave transmission tower technicians suffering higher % rates of testicular cancer ( I forget the numbers but the increase percentage wise was significant and noteworthy ) is a counter point to the cellphone belt case, as is the significant increases in testicular cancer by police officers who regularly placed their traffic radar guns in their groin not knowing the hazards of microwaves.

    So, while I acknowledge your expertise in physics (your PhD attests to that), I certainly call into question your reading and expertise in the effect of microwaves on increasing cancer incidences, even your cursory knowledge of cell phone microwave emissions behavior / operation and its impact on experiment conditions and conclusions thereof?

    The (highly variable) position of the cell phone on the belt is unlikely to result in sufficient local dosing to the same exact tissue when operated in standby pinging and repeatedly replaced on the belt in relation to exact underlying tissue exposed to the low (duty cycle) cell site power pinging. The movement / positional irreproducbility is very likely to reduce peak dosing to a specific same tissue, if you give this some deeper thought, experimental and not theoretical in nature.

    Yours Truly,


  39. Wolf said

    Below is an except of the conclusion from this report

    the difference between what several here at this discussion board prematurely and wrongly claim as safety with respect to cancer risks of microwaves and the reality of the cancer risks, as also risks in birth mutations from microwave exposures, is quite telling.

    There is a small section where they do indeed indicate that attempts to make differences between ionizing and non ionizing radiation with respect to cancer incidences are very weak indeed. I’d heartily agree, and qualify this as there is dose and means of exposure, and frequency of the source effects. Moreover short term safety has little bearing on cancer incidence conclusions.

    Yours Truly,

    ( strong beleiver in scientific literature searches [as google scholar]
    as being helpful in reaching useful conclusions )

    report excerpt quoted


    Available data suggest that RF radiation be considered a carcinogenic risk, a position already taken in an internal U.S. EPA document (51) in 1990 when there was much less evidence of the potential harmfulness of RF radiation.

    Except for the Moscow staff, which includes both workers and dependents, most of the exposures studied are relevant to occupation. The most relevant to cases of community exposure risks today are those involving populations living near broadcast facilities. Cellular telephone users have not been exposed in definable numbers for a long enough time period for an adequate study to be made of cancer incidence.

    However, interpretations must take into account the report of the Repacholi et (52) of lymphoma-prone mice, who showed a doubling of the incidence of lymphoma over an 18-month period when exposed to modulated radiation similar to far-field cellular telephone exposures. This initial finding of experimental evidence of cancer from cellular-telephonelike exposures emphasizes the importance of examining epidemiologic evidence of such effects. Possibly the most suitable source for such data would be the more detailed study of exposures of military personnel or air traffic controllers who received definable exposures and have undergone a sufficient period of follow-up. Evaluation of such nonspecific symtoms as headache, sleep disturbances, and unfavorable reproductive outcomes of populations living near broadcast facilities should have priority for community studies.

    The evidence may or may not justify more restrictive regulation of occupational exposure; for community exposures, however, the evidence justifies prudent avoidance (14,15). The concept has been presented by a group of Swedish government agencies in response to the evidence concerning ELF exposures. The plan is basically voluntary and stresses education about risks and economic analysis of uncertain risks and the possible costs of their avoidance.

    Included among the actions to take under the rubric of prudent avoidance is epidemiologic monitoring (53), a system of standardized health status measurements of presumably reversible effects, which can, if unfavorable trends are discerned, become the basis for higher levels of population protection. The availability of a number of potentially reversible biologic responses makes this an unusually attractive possibility.

    A second type of action is to provide realistic procedures to minimize the exposures. Shielding the head and face from exposures to the antennae of hand-held cellular telephones, and guidelines for keeping an adequate distance between broadcasting sources and civilian populations, are clearly indicated.

    Further work is needed on the possibility of carcinogenicity in experimental systems of RF exposures. These systems should be separate from evaluations of ELF, which does not appear to have the same set of effects.

    This review casts some doubt on efforts to distinguish ionizing from nonionizing radiation with respect to their health effects. It also raises doubt about the protective role of regulations based solely on the thermal effects of RF radiation, which is the basis for current standards.

    There seems to be some evidence from the Moscow study and community studies in the vicinity of large FM and TV broadcasting facilities that >>>>> “””exposures as low as 2 µW/cm2 may have long-term health effects.””” <<<<<<

    A comprehensive and critical review of the epidemiologic data available on health risks from RF exposure should be carried out and the reasonable measures for avoidance of the identified risks should be described and evaluated. “

  40. Dan Lantz said

    Alienthe #37:

    Don’t be concerned about those who have already made up their mind. Over the last 30+ years, I have learned that Space industrialization/bioization is a terrifying topic for many. Usually, the microwave danger possibility is the excuse to do no further thinking. The “logic” seems to be that any possible danger makes the whole idea preposterous. I have monitored the oven/cell phone studies for those years, primarily interested in the popular perception/reporting. Also having studied physics, it seems clear to me that, unlike ionizing radiation (photon and other), (at life temps) there is a level below which microwaves are perfectly safe. To the point that a perpetual motion machine could be built from any supposed danger mechanism. I suspect this level is where the microwave total flux is equal to the internal infrared flux (many more microwave photons than infrared), at life temp. The beauty is that the higher exposure experiments are being conducted on a massive scale for free, so there is no need for opinion.
    Those who have not had had time to check out the Space proposals will have missed the ongoing concerns with possible beam dangers. O’Neill mentions them. Criswell’s reference plan is for beam 20% solar, but sez will work at 2% solar if safety problem is found. (Hint: don’t block the beam!) In most of space, you need 3 feet of shielding to protect from natural radiation (unless below Earth’s Van Allen Belts), so you are protected from microwaves for free. LEO moves thru the beam in a fraction of a second.
    Some may also have missed the various comparisons of PV and CSTP collection systems in Space. PV is usually favored, I suspect because there seems to be more hope for PV improvement. Space CSTP needs (true) radiators (not heat exchangers), which are an added expense. Either way, whatever works best on Earth will also work in Space, with greater efficiency, no clouds/dust/birds and no need for long distance Earth transmission lines. Don’t forget the wind! It will blow down mirrors and PV panels unless they are thousands of times more massive than their Space or lunar cousins.
    An oft missed point with such systems as geothermal, fusion/fission, CSTP and PV on Earth is the waste heat load on the environment. Geothermal releases heat that is there but would slowly seep out. Fusion/fission, geotherm and CSTP run a turbine, little hope for over 50% efficiency. CSTP and PV collect all the solar they can, displacing direct (sand) reflection back into space or, even worse, plants (land or water) that would use energy to grab Carbon. This comes into focus when the 20-200 TWe needed wastes another 50-500 TWt into the environment.
    Of course, long before Space is supplying even a fraction of the Earth’s energy needs, the effort will open opportunities for mining and manufacturing in Space, which is an even better way to avoid environmental problems.

  41. Coyote said

    Wolf, Alienthe, and Dan Lantz,

    WOW! You guys are great. This conversation is excellent and very instructive to me, as I’m sure it is to our adoring fans on the sidelines. (Yes, we have adoring fans. Soon we’ll have groupies and the paparazzi will be after us. So, hold on!)

    Let’s shift this discussion a little bit to think about the standard legal questions regarding safety that will have to be answered prior to acquiring bandwidth from the ICC. Safety questions will also arise prior to launch for insurance purposes. Liability and indemnity will have to be established…and these will be prerequisite to registering and licensing solar power satellites.

    For the sake of arguing the more important points, let’s assume that we are bunch of attractive and highly-paid insurance lawyers who must have the safety of a space solar power system demonstrated to our satisfaction prior to our company accepting the risks of liability and indemnity.

    From that perspective, let’s consider both microwave and laser power beaming as options, and accept as a matter of clinical discovery that both methods will have pros and cons when it comes to the full gambit of safety issues. There will also be operational measures that could be employed to mitigate risks.

    Please discuss your thoughts on how the space solar power community can best establish the safety pros and cons as well as risk mitigation methods for both microwave and laser power beaming from space.

    Which method will we, as attractive and highly paid insurance lawyers, prefer and what risk mitigation methods will we insist on?

  42. Alienthe said

    Coyote #41: I have a few issues regarding Wolf #38; however if your post is a request to hold fire I will do so.

    If the question is shifted towards the liability we are talking due diligence and good faith (jurisdiction depending, a major question in itself as the satellites will be in orbit over large areas of Earth).

    Regarding microwaves there is plenty, much gathered by defense with respect to defense related radars and microwave communication links, later on in civilian areas like comm links, police radars and phones, particularly DECT which tends to radiate a lot. There is a lot of material and it is a hot debate in spite of world wide use over decades. Latest I heard on that front was a possibility of higher cancer incidence in the right eye due to phone proximity but again debate rages on. What is certain is that the conclusion is far off yet.

    Regarding optical transmission you have a number of options. Lasers are frequently mentioned here though I am not sure why since plain linear optics is simpler and parametric amplifiers another possibility. Coherent light can be more dangerous than incoherent (“plain”) light, another reason to prefer simplicity. Solar incidence is about 1KW/sqm, though it is well known that women in need (?) of a speedy tan use mirrors and thus at least double that power density. Exposure to sun at sea or with a snow cover can also increase power density. With the exception of UV light and purely thermal effects I have never heard this is dangerous. Nevertheless experiments should be performed.

    Some advantages of light:
    – obvious and thus non-scary
    – simple in transmission and reception
    – limited absorption in clear weather
    – multiple applications
    – stimulates eye blink reflex for added safety
    – easy shielding against unwanted radiation with alu foil (tin foil cowboy hats anyone?)

    My preference is therefore colour filtered incoherent light at power rates up to 5KW/sqm near civilian populated areas, 30 KW/sqm in areas with specialists only and possibly more when stimulating photosynthesis in the oceans.

  43. Dan Lantz said

    Coyote #41:

    Don’t try to get me into being a lawyer! I dropped out of law school with over two-thirds completed when I realized how crazy they were!
    As a physics major, I learned that energy was the primary consideration when judging possible effects. If the energy is not there, the effect is impossible. More importantly, I learned the difference between testable and non-testable claims. You have probably observed that I have made no claims one way or the other as to the safety of microwaves. Why waste time on opinion upon an observable outcome? Let the cell phone industry do the work, and adapt the power beams to the resultant findings.
    We can observe, however, that people are willing to risk great danger to answer a call from their girlfriend. Cell phone use presents a danger that is at least as great as being drunk when driving, far greater a risk than from the microwave exposure (if any). This alone should encourage us to persue solving the great problems of the biosphere thru Space industrialization, despite those who are afraid of any risk whatsoever (whenever such fear supports their pre-existing position).
    Risk is a balance, not an absolute to be avoided at any cost. Failure to accept any risk when the very life of the Earth is at peril is symptomatic.
    Let the truth of the matter be known!

  44. Dear Forum:

    Long-time reader; first time blogger.

    I am trying to understand the discussion around the health effects of microwave energy. What does any of this have to do with space-based solar power? How is this forum an appropriate venue for a discussion on the health effects of microwave energy? Wouldn’t a forum on health or cancer be a better venue for this discussion? Don’t get the relevance.

    All this makes me doubt the sincerity of those arguing the adverse health effects of microwave energy. Makes me wonder if this ‘health hysteria’ about space-based solar power (which is at best a concept at this time) isn’t some anti-growth cover or competitive bias in favor of another means of power transmission.

    Hope the forum will stick to SSP feasibility.

    Personally, I’d like to discuss a funding strategy for SSP. Long-term power supply contracts have proven useful in supporting new power generation technology.



  45. Edawg said

    The public may be scared off by the idea of microwaves.I heard about a 60 minutes special about the Army’s new microwave crowd control Humvee (VMAD) that is being considered a torture weapon by some.If public pressure continues to build it may be an uphill battle pushing for a microwave SSP and fighting that battle may make enough sense as letting fighter pilots use cell phones while they are flying!

  46. Edawg:

    Okay. Still don’t understand what this has to do with SSP. May I suggest another forum about health.

    It’s possible microwave transmission may serve as a bridge technology to another (less risky) transmission methodology.


  47. Dan Lantz said

    Coyote #41, Alienthe #42, Michael #44-46 and Edawg #45:

    Michael-microwaves beamed to Earth from SPS were the starting plan in 1968(Glaser), and have been the ususal assumption.
    Altho not “married” to microwaves as opposed to lasers or plain light (or other) as the power beam, I think microwave system has advantages.
    Consider #42 “Some advantages of light:”

    “- obvious and thus non-scary”
    -or- Inherent weakness of microwave beam (because cannot be sharply focused) is problem for receivers, but also makes impossible to convert to (long range, at least) weapon. Edawg’s Humvee example is short range, more like an oven. Laser weapons are already being tested at long range.

    “- simple in transmission and reception”
    -or- Waste heat from laser/light will be dissipated on Earth surface, unless there are much more efficient ways to gather than current photo-voltaics do sunlight. Microwaves are much more efficiently received, waste heat dumped in Space/on Moon.
    Also, microwaves have such long wavelength (low frequency) that can make phased array transmitter that serves multiple receivers (rectennae) simultaneously, and aim rather well considering wavelength. Don’t know if phased array yet possible with visible laser/light, but may(?) be other optical solution that does as well.

    “- limited absorption in clear weather”
    -or- Microwaves’ frequency is selected to penetrate not only atmosphere, but clouds and haze, even if persistent for long periods.

    “- multiple applications”
    -or- The electricity gathered from microwave beam is as good as any other. If only lighting is needed, simple mirrors in orbit may do.

    “- stimulates eye blink reflex for added safety”
    -or- I would rather be exposed to microwaves!

    “- easy shielding against unwanted radiation with alu foil (tin foil cowboy hats anyone?)”
    -or- Same shielding works for microwaves, except can have holes to look thru (and watch food cook).

    Time for popcorn!

  48. Neil Cox said

    Hi Michael: As Dan suggested, most everything involves some risk. How much risk is acceptable is a reasonable discussion point for SSP. Ie The microwave crowd control humvee (menioned by Edawg)will all but surely cause a few people a permanent injury but it’s use is appropriate if injury and death to innocent persons is avoided by controling the crowd. Microwaves, coherent light and incoherent light are the only three ways of delivering the solar energy from space to Earth’s surface. A threshold energy level will produce very rare injuries. This is acceptable to free our planet from Arab oil. Perhaps even rather frequent injuries and death are acceptable, if it accomplishes this life or death task. Neil

  49. Dan Lantz said

    Neil #48:

    One thing to remember about microwaves and light in general (laser or regular) is that the individual photons are non-ionizing for liquid water temp materials, until energies in UV or above are used. There is thus NOT the problem associated with various things like x-rays, cosmic rays and nuclear radiation in which any amount is dangerous, to some extent. There is thus, as you say, a threshold level to be found before safety becomes an issue.
    Also, it may seem counter-intuitive, but the problem is not WHERE the oil (or coal) comes from. There is already more supply than can be used! At a stable (inflation-corrected) $30 per barrel, all sorts of shale oil, tar sands etc are avail. These were not developed in the last 30 years because oil was too cheap! The limit is in the emmissions. Criswell’s Lunar
    Solar Power plan can eventually deliver power for less than a reasonable Carbon tax on Earth burned coal. And open Space.

  50. Hubert Davis said

    All of this discussion about human safety strikes me as being premature, perhaps even immature – – a good systems study will clearly include safety assessment, by people best qualified to conduct the studies. There is a lot of background by space medicine people, far better qualified than am I – – or Wolf.

    Let’s get specific about what we plan to do in demonstration and technology development, focus attention on that specific set of hazards and not get sidetracked by discussions regarding microwave ovens or cell phones.

    All radiation, including sunlight, has some hazards. Ask your dermatologist!

  51. Edawg said

    Dan and everyone,

    I just wanted to share this.

    Microwaves and lasers represent different branches on a technology tree each branch represents millions and billions of dollars in R&D funding.I dont think im cut out for this side of the forum , thinking about how a microwave oven works gives me a headache.

    Now for hard question which branch of the tech tree has a better payoff in the long run from a funding-military point of view?Or should we just throw a Marine in a advanced weapons bunker and see what “toy” he comes out with? 😛

  52. Neil Cox said

    As I suggested in my post 32, an SSP beam for moving military vehicles needs to illuminate about ten square meters or less, so the beam needs to be about ten kilowatts per square meter = one watt per square centimeter, average. I don’t think this high a power density is possible for centimeter microwaves, perhaps not even millimeter waves, so laser looks best for this application and small scale electric grid purposes. Laser has the advantage that thousands of existing photovoltaic receiving sites can receive the beam, while microwave requires R & D plus construction of rectennas. Some unplesent surprises may occur when we start building very large rectennas. If we decide it is impractical to do both laser and microwave, I suggest we drop microwave. Neil

  53. Dan Lantz said

    Hubert #50:

    I fully agree with Hubert that funded safety studies “by people best qualified to conduct the studies” are both inevitable and desirable.
    I also agree that safety discussion is a sidetrack to some extent, given that “Let’s get specific” designs (Criswell’s Lunar Solar Power, for example) plan for any safety issue that may reasonably arise by being able to work at very low beam levels, if needed.
    Indeed, I have pointed out in the past that assertions about microwave safety are testable claims, and thus having opinions about them is a waste of time.
    However, over the last 30+ years of promoting Space Solar Power, the vast majority of objections I have heard are based upon assumed beam danger. A small but proximate example would be the mis-attribution to dermatologists. They warn against ionizing UV solar radiation.
    So, why not take advantage of this inherent interest? International controversy about “death ray” power beams will introduce the basic concepts, followed by findings that they are as safe as cell phones, and safer than ovens!

    Edawg #51:

    Good site! I tend to not try to “boost” any particular method or technology. When I first started doing this, nanotech was yet undemonstrated, and things are likely to keep on changin’.
    I tend to try to point out things that are somehow counter-intuitive (and, ideally, important!):
    -You want to live, manufacture and build in Free Space, not on a planetary surface.
    -You want to collect sunlight on a pre-existing surface, that has no atmosphere.
    -You cannot launch very much from Earth’s surface, nor should you.
    -Most things humans want to do are much easier done in Space than on Earth, once you get started.

    The “crown” of the Technology Tree, or at least a major branching, is Earth vs. Space based living/technolgy. As O’Neill asked his first year Physics class: “Is a planetary surface the right place for an expanding technological civilization?”

  54. Robert said

    I hope some small group, in the near future, will sit the presidential candidates down and deliver to them the quintessential Powerpoint on SSP, energy revamp and security, and space settlement. Col. Coyote gets my vote for leading that group.

  55. Neil Cox said

    I think adequate studies of safety have already been done, and SSP is a slight risk to persons who are at the wrong place at the wrong time. There is little point in studying microwave safety, if we decide to use lasers or shorter wave length microwave. We have to accept slight risk connected with nearly all human activities, especially the large scale needed to reduce our dependace on Arab oil. New safety studies are less likely to be honest than the old studies because ethics and honesty have decreased considerably in recent decades.
    Are there some nano tech products I can buy at Walmart? If not, Nano tech will likely be little help in constructing a SSP in 2015, which in my opinion should be our goal. Look how long it has taken to mass produce super conductors, electric cars, fission powered cargo ships etc?
    The hundred persons who have lived on Mir and the space station are not strong evidence that humans, by the millions can live in space or on moons and asteroids. Likely we will do this in 50 or 100 years, if we start building SSP by 2015.
    Go team go! Neil

  56. Dan Lantz said

    Is very interesting, esp from ISRU (In SPACE Resource Use) point of view.
    (“In SITU Resource Use” leads one to think of staying on planetarty surface, rather than using the mined/collected material where ever you want, such as In Free SPACE)
    Several points:
    -You would be waiting a long time for launch costs to drop to the point where mass radiation shielding could be launched from Earth.
    -Zero g has bone loss, weakness and recently indicated immune system problems. Combine artificial g with mass radiation shielding only possible with ISRU.
    -Once need for shielding (outside LEO) and artificial g is recognized, SSP project can share ISRU infrastructure with shielding/arificial g effort (humans to Mars, Moon or elsewhere).
    -SSP using (lunar) ISRU leads to Criswell’s Lunar Solar Power system.

  57. Dan Lantz said

    Add to #56:

  58. Robert said

    Dan #56:

    Edawg wrote in response to “solar-fired space-based processing plant” in the Tech Pieces posting: “…you could have an all in one SSP plant/ISRU facility!” I suggest everyone refer to O’Neill’s “Alternative Plan for US National Space Program”, which addressed EVERYTHING for political ears in 1989-90. It is still available on Shielding and bulk construction materials should be launched via Mass Driver from lunar excavations, one bucket per second, to a Mass Catcher at L-2. Transport it from there to a solar-fired SPACE-based processing plant, separate for oxygen, silicon, metals, and glass, and make products at that site. Why are new authors trying to re-invent and rehash what already is? A second point, the bolder the better. Let’s do what O’Neill said to do, and do it with both feet in. Once we have 2 serious presidential candidates front and center, someone (with weight) give them, in quiet fashion, that Powerpoint!

  59. Edawg said


    thats why we need nuclear propulsion or something better.If we got good engines the rad shielding will wont be much of an issue.Screw mass fractions this problem was solved with NERVA

  60. John V said

    Per Andrew (#17), has anybody contacted the XPrize Foundation about a competition? I submitted a proposal to their web site and they sent me the official, seven page form. 🙂

    Anybody want to help me fill it out?

    John V

  61. Dan Lantz said

    Robert #58:

    Having read “The High Frontier” in 1977, I am in general agreement/understanding/excitement with the overall “in Space” outlook, ISRU in particular. I also try to get people to avoid thinking that they have to/should live on some planet somewhere. I fully believed that Solar Power Satellites were the best way to get things going, until ~1990, when I heard of Criswell’s Lunar Solar Power system. It is a correction to O’Neill on one small point: the MOON IS THE SOLAR POWER SATELLITE! Criswell estimates it is 50-100 times easier to put collectors on Moon than in Clarke orbit. Worth a look, no?

    Edawg #59:

    No matter how good the rocket, it just makes ISRU that much easier to start!

  62. Robert said

    Dan #61:

    The first flood of thoughts about moon-as-solar-collecting-device:

    1. There is a night/day cycle to contend with on the lunar surface.
    2. The moon is not geosynchronous, how to fix the beam on a single receiving area on the ground (or is there another interesting scheme?)
    3. The moon is considerably more distant than geo, seems like it makes for a very diffuse beam and less powerful delivery capability than from geo collectors.
    4. Criwell’s idea takes away my “moon-dug large dark monolith in space leading to Krafft Ehricke’s Homo Extraterrestris” imagery imparted by Kubrick/Clarke in those old MGM Panavision movie reels at the Webb Theater in beautiful downtown Gastonia back in the day.

    You don’t have to answer the above. If it’s in the Criswell material I’ll Google it. Maybe it’s the quick start solution after all.

  63. Robert said

    Correction to 62.
    Yikes, I just Googled K. Ehricke. Too many unfortunate associations with him some years after his innocent-sounding 1978 writing on “The Extra Terrestrial Imperative”. Keep the violent and the weird folks out of SSP efforts, please.

  64. Neil Cox said

    Hi Robert: We can sort of fix the Moon’s day-night cycle by locating on mountain tops at the lunar North and South pole. A problem not usually noted is the photovoltaic panels need to face the horizon and rotate a bit more than 360 degrees each month. This can be partly fixed by rotating concentrating mirrors and/or not using the photovoltaic panels that are facing the wrong way about 15 days out of each month. While the sun is above the horizon all, or most of the month, from these special locations, Earth is below the horizon at least a few days per month. This can sort of be fixed by sending the beam to a satellite or statite a few hundred kilometers (or more) above the moon’s surface. It is thought that a phased array redirect antenna can then send the beam to Earth, with only modest energy loss. As far as I know this technology is largely untested at even a tiny fraction of the power levels and beam narrowness needed. Also it is not needed about 20 days out of a typical month, but it might serve other useful purposes after we have a large presence on the moon.
    The next problem is that the moon is below Earth’s horizon at a typical receiving site on Earth about 12 almost random hours per day. A sort of fix is another phased array redirect near or not so near Earth.
    We can, of course, use the rectenna only when things line up right, but that is the critism of Earth’s surface solar wind, wave and tide power. You likely guessed that I am not a big fan of SSP on the Moon. I agree the ten times farther than GEO is a sizeable obstical, especially for the less than a gigawatt SSP we will build the next 4 decades or more. Neil

  65. Dan Lantz said

    Robert #62, 63:

    Ericke rehabilitated himself after WW-II. If you have not read “Gravity’s Rainbow” by Thomas Pynchon, you have a pleasant surprise!
    Be specific about problems with Criswell’s plans, and we may be able to make some contribution to the advancement of humanity.

  66. Dan Lantz said

    Robert #62, 63, Neil #64:

    My poof weeder is on a long break. Ehricke.
    Robert 1.
    Criswell proposes pairs of lunar solar “farms”, which in total may be thought of as arcs for simplicity, even tho they are not continuous. One pair of arcs would be on opposite parts of the limb (edge) of the Moon, just slightly to the near side. All of the transmitters would be there. Another pair of arcs would be just around on the “near” far side, with short cables to the transmitters. Thus most of the time either both East or both West arcs are illuminated, and all transmission is from the lit side of the Moon. At New Moon, only the two arcs on the far side are lit, and all power is first cabled. At Full Moon, only arcs on near side are lit, no power is cabled. Need 2x the collectors, and 2x the transmitters plus some cable to make up for lunar day/night cycle, compared to Solar Power Satellites. East-West running parabolic cross-section troughs can mirror to high intensity rated cells for very little loss due to Moon’s rotation (Sun “moving”). This is helped by very small seasonal effect on Moon. Or North-South running stand up tent shaped simple cells work pretty good without having to move. Another factor of 2x for tent design.
    2. All plans I have seen have many times more receiving rectennae than transmitters, and use phased array transmitter’s capability to send multiple beams at same time. Pilot signal from rectenna both tells transmitter where it is and how much energy to send, and is needed to focus beam for added safety. Rectennae do not point to spot like satellite dish does.
    3. You do need larger transmitter, but that may not be a problem if you need larger transmitter to handle power load anyway. Don’t know if that is true, however.
    Also, as Neil points out, the Moon is only “up” about a third of the time, but never “down” for even a whole day, except in polar areas. Retransmitting antennae fill in here, and may always be used if technique used to transmit thru Space different from thru atmospere.
    So, there are trades to look at, but huge advantage in having “satellite” already in place.

  67. Edawg said

    For LSSP to work Aries 1 needs to get killed.Is it just me or is it retarded to launch a big ship and then a smaller ship.Why not two cheap Aries V/Jupiter232(direct option2.0)boosters? If space is ever going to work we need to face economic realities.What a wacky thought =P

  68. Dan Lantz said

    Edawg #67:

    Without getting specific as to Aries I or V designs, I do have a general “rule” for launch systems: You must pick any two of (1)big, (2)safe and (3)cheap. If you want big (cargo) and safe (people), you are not going to get cheap, for any given background level of technology.
    The Shuttle tries to be big and safe, and it is not cheap. I suspect Aries V is not as safe as Aries I. Incidentally, there is private interest in upgrading existing cargo rockets to manned rating, for tourism.
    There is a similar “rule” for payload: you cannot have low mass, safe(and/or effective) and cheap. This is the main driver for ISRU, other than launch cost itself. ISRU product does not have to be low mass, as it is either not launched at all, or launched from Moon/asteroid, much easier than from Earth.
    Space/ISRU economic reality is that there are two “tipping points” to work towards. The first is where the ISRU product is cheaper than the functionally equivalent launched product, including launch cost. Things like Oxygen from lunar materials come to mind, for use in Space. The second is where ISRU product is cheaper than Earth produced product, when not launched! SSP may be the first such product. Asteriod/Moon mined/Space refined metals brought back to Earth cheaper than mined here would follow.
    Getting to these “tipping points” is one of those situations where small initial variations in the plan can lead to great differences in the outcome. Well worth a lot of effort!

  69. Robert said

    There seems to be a sort of a parting of understanding here between the solar power satellite folks and the LSP folks. I hope I’m wrong. My understanding about the SPS program is that it would put workers and their families and other species in gravitied towns in free space sooner rather than later for rational reasons (the industrial reason to do that). The LSP rationale doesn’t seem to require that: a few technicians on the moon and telerobotics would get the job done. The proponents of ground-based solutions (fission, fusion, biomass, wind, geothermal, ground-based solar, “clean coal”, etc.) have never required or addressed anything in the way of a bold vision of humans living permanently in space. I can guess that nobody seems averse to having species going to space “someday” but, with the exception of the SPS rationale, they ain’t building-in a rational reason to do it, and their science-fiction tells them to imagine colonies on Mars(!) Nobody needs to go around manufacturing new religions or political threats to do these things, but isn’t survival of species and growth beyond the home planet a worthy component of anything we do in SSP?

  70. Dan Lantz said

    Robert #69:
    is a view of the “problem” you bring up: LSP is too easy!
    O’Neill wrote extensively of the “bootstrap” nature of getting started in Space. LSP is the ideal way to open Space, as it is likely the first AFFORDABLE large project! Once manufacturing of solar cells on the Moon starts, all manner of other things will become possible. This is not AFTER LSP, but as soon as it starts. I want a place to live before I go, built by telebots, so I can stay as long as I want in somewhat Earth-like conditions. As soon as possible.

  71. Robert said

    Hi Dan,
    Thanks. Combs points out a possible cost reduction with LSP by a factor of 50 vs. SPS while escaping a pesky “orbital debris problem”. He mentions the disadvantage of a 50% duty cycle with the moon’s day/night cycle, and raises the question of whether the refinery and mfg. facilities are located in free space or on the moon. Legacy O’Neill folks don’t insist that Criswell is wrong, as more info is needed. I guess the exciting question of the day is what will be the optimum “starter”. Where do you and your kids want to live, by the way? Is there enough gravity at your place for a swingset?

  72. Edawg said

    #68#70 Dan
    Its a cargo issue ,getting to the right tipping point will require a massive amount of tonnage to be placed on Luna for ISRU for use in LSP or SSP construction.Will we send hundreds of payload to the moon to get ISRU started or will we just land a few “big birds” to get the tools in place?Without ISRU for SSP the colonization of the solar system will be pushed back another 100 years..

    #63 Robert
    Keeping violent and weird folks out of space may spell doom for our species if the galaxy has any resemblance to the Amazon

  73. Dan Lantz said

    Robert #71:

    My goal in this project has always been to raise the very “exciting question” you mention. There is a strong starting assumption favoring Solar Power Satellites over Lunar Solar Power, as you can see by reading the otherwise excellent Ad Astra Special Report issue. This is quite understandable given the ~20 year head start SPS plan had, and I am not calling foul.
    Another (past) goal has been to cause consideration of In Space Resource Use (ISRU) whatever the SPS vs LSP decision is. (They are not totally exclusive, by the way!) This goal seems to have been met. Prior SPS studies ignored ISRU as too “far out”, then concluded that launch costs made SPS impractical. Duh! We should not make similar mistake by ignoring LSP in careful studies.
    I want to be clear that I favor O’Neill’s overall plan, and want to primarily live/work/manufacture in Free Space! ISRU will quite early supply both artificial g of 1 and radiation shielding. For Mars ship, space station(s) and L5 habitat, etc. As you say, “both feet”. LSP is an exception to O’Neill’s plan, only in that so much of what is needed for SSP is already there!

    Edawg #72:

    “Without ISRU for SSP the colonization of the solar system will be pushed back another 100 years..”
    That’s the right attitude, dude! I have been pushing ISRU for 30+ years, as the FIRST step, before Mars (manned, at least) and even before space station of any significant size. The objection has always been that the “pet” project can’t wait for ISRU. The result: no “pet” project at all in some cases!
    The “best” plan for ISRU has yet to be worked out. Seeing that ISRU is the way to proceed is only now being widely recognized. Probably, there will be generations of tools making “heavy-dumb” tool parts, with the electronics/motors/bearings being launched. Or, inflate the structural shape with “smart” stuff in place, spray on (vapor deposit) metal for basic structure. Some have proposed starting with very small robots in large numbers. ISRU leads to more ISRU.

  74. Neil Cox said

    Yes, very small robots, plus some up to ten tons. I see little point in thinking many robots, until we have the first hundred robots with perhaps 50 different specialties operating in space sucessfully for ten years or more. Will a trillion = a million times a million dollars get us there before 2040? Can we wait until 2040 to reduce our dependence on Arab oil? Can we convince the tax payers that this is a trillion dollars well spent? Probably not with pay back 30 plus years in the future. I see little choice but to demonstrate SSP with high altitude balloons, then in low Earth orbit, then in solar sychronous orbit, perhaps never at GEO or the moon, if the lesser SSP do not work as well as we hope. I agree we can work all these plans in parallel, perhaps spending a few million dollars on each. Neither taxpayers nor investors are likely to spend billions until payback is closer than ten years. I’m puzzeled how the nuclear fusion people got all that money, but it appears The USA has temporarilly abandoned fusion. Like fusion, attempts at SSP, asteroid colonies, free floating space colonies and moon colonies, will produce valuable technology advances even if the goals remains elusive. Neil

  75. Dan Lantz said

    is info as to why ISRU is needed (to provide radiation shield as well as g), not just off in the future, but NOW!

  76. Robert said

    As right wing talkers position themselves to hijack the elections (Rush Limbaugh hints at taking over matters when he’s done with the Democrats) and “space advocates” like Dr. David Livingston sabotage SSP by removing the arguing points, I wonder if mankind is worth saving? Really now, my grad paper was written on the Fairness Doctrine, of all things, which was killed on August 7, 1987 by a misguided FCC. In the interest of political sanity in the public square, Congress should codify the Fairness Doctrine and a friendly President should sign it. Only then will we be back on the tracks and move the show into space by an even-tempered and fairly informed population.

  77. Edawg said

    Rob it will have to be a bi-party solution.and im not that impressed with what the Democrats have now.Im an Independent anyways .I dont even like the Fcc

    News by
    Steven Hawking

  78. Edawg said

    ~ISRU leads to more ISRU.

    And ya have an economic system!With the credit crunch we are back to a commodities market and I know there are plenty of metals in the Solar System.Ya just gotta convince the public!Or our crappy education sytem

  79. Dan Lantz said

    Edawg 77-78:

    Not to be “down” on Hawking, but I watched his NASA 50th speech and he seems unaware of two key points:
    1. SSP WILL solve many Earth problems, particularly the Carbon problem (which he mentioned specifically), if we do it quickly enuf!
    2. You do not have to (wait to) go to other stars’ planets for the long term survival of the bio system of Earth, including humans. Solar orbiting O’Neill habitats will do the trick much earlier.

    As to your point about “economic system!”, this means we gotta convince a few investors/companies with enuf clout to help get the legal/treaty system amenable to SSP, and do it! Waiting around for the gov/public to pave the way “admits” SSP is not so good. I think the plan is quite good, and will make LOTS of MONEY! Gov cooperation is great, but full dependency on gov “initiative” is a good way to miss this boat.

    One more ISRU factor: the more lunar ISRU is involved in SSP, the more Lunar Solar Power is favored when compared to SPS.

  80. Edawg said

    ~to help get the legal/treaty system amenable to SSP

    There really needs to be a international frame work for this issue of space utilization..I almost got ripped off in one of my business ventures..

  81. Dan Lantz said

    Edawg #80:

    One of the things I’ve learned in the last 30+ years of promoting SSP is that “dark” forces are against it. Realizing that the future is “in the stars” causes power addicts untold consternation. See the charter of SSI for more on this issue! More to come!

  82. Edawg said

    Yup and having National Security benefits causes SSP to be a major hacker attractor.At this point in the game space power comes from the “barrel of a gun”or the almighty dollar.

  83. Robert said

    Does anybody here have any opinions or fast conclusions on the global warming (global climate change) argument? I noticed that Steven Milloy, the founder of, was interviewed on the 3/25/08 edition of The Space Show, where he spent most of the hour slicing global warming consensus every way he could and Dr. Livingston, “space advocate” that he professes to be, agreed with him. Incidentally, on the same show, Milloy expressed that it would be “pretty cool” to send a man to Mars and return him safely to earth if they could “find a volunteer”. This man’s parochial view of space programs, which rehashes the “flags and footprints” political rationale for Apollo, is astonishing. When asked finally late in the show what he thought about SSP, he apparently knew little to nothing about it. Milloy is a weekly contributor to Fox News and he presents himself as empirically literate. Milloy’s new entry of 5/1/08 on dismisses climatologists and the search for alternative energy, and brands Gov. Schwarzeneggar, Sergey Brin, and Larry Page as foolish. He continues to attack Al Gore for his environmentalism. I remember when O’Neill, Sagan, and respected others talked and wrote about greenhouse gas emissions and protection of the biosphere as a starter reason to do alternative energy. I have a videotape of Dr. Sagan addressing the 1990 Emerging Issues Forum at NCSU, where he drew lessons from the atmospheric conditions of both Mars and Venus as illustrations on what can happen with a runaway greenhouse effect (two separate effects on two different planets). Even in 1990, Sagan was talking about global warming, and he was scientifically, not politically, motivated in speaking to audiences about the subject. Environmental concerns defined a lot of Sagan’s and O’Neill’s educational efforts. Now that they are dead, and amplified shortsighted right wing voices drown out voices of reason and foresight in the current muddy “marketplace of ideas”, what best action is there? Will the “energy independence and security” argument ALONE suffice for public acceptance of SSP funding? NSSO is comprised of smart, traveled, tested, and educated people, and I trust from their wise ecumenical approach and words in the Interim Assessment that they will continue to plow down the path of empirical truth and reason in the interest of a better future for all and not permit political vagaries to sway them.

  84. Neil Cox said

    A lot of bad science has been circulated in the popular media on both sides of the global warming/climate change debate. My guess is about one degree f warming occured in the past century up to about 1998. This was mostly natural cycles, but human emitted carbon dioxide, contributed slightly to the warming. I recomend grants for promising technology to reduce and/or sequester carbon dioxide and funding some small pilot programs, but let’s not spend billions on carbon dioxide abatement. On the other hand, our dependence on Arab oil is dangerous, and we should be extravigent in finding remedies. SSP looks promising for reducing carbon dioxide emissions, for reducing other dangerous polutants and for reducing our dependence on Arab oil. Neil

  85. Des Emery said

    Global Warming is an attempt by Earth itself to maintain its ‘balance.’ As of course we know from “for every force, there is an equal but opposite force” operating at the same time. Jupiter’s Great Red Spot is a storm of unimaginable fury but seen by us over the past many centuries as a ‘stable’ event, regularly rotating into our view as the planet turns. On Earth we should not expect that pumping energy into our atmosphere will not affect ‘weather’ or ‘climate.’

    The carbon stored in fossil fuels over many millions of years can not be released within the period of a few hundred years without repercussions which we are now beginning to experience.

    The melt, well-documented by many scientists, of the Arctic and Antarctic icecaps, and of the glaciers around the world, especially the ones covering Greenland, is evidence of that change. Earth works hard to maintain an equilibrium, using jetstreams in the atmosphere to shift heat from south to north (the opposite down under) and surges in the oceans, like El Nino and La Nina, which transport warmth from west to east in the Pacific.

    Which is reason enough to reach for solar power to replace carbon as our energy source. And urgency enough to make it happen now. And visionary enough to make it our first step into Space.

  86. Edawg said

    If we want ssp to be a political issue (it has to be in order to succeed )someone has to ram a study down there incompetent throats.And defend ther viepoint like a cougar.Alought of pro space people are to scared to upset party politics.Nothing risked nothing gained

  87. Bill Rothschild said

    Regarding the demo at the ISS… A NASA/DOD/Industry team is considered what could be demonstrated by 2010 using existing equipment and facilities. Demo of wireless power transmission from space to ground (mutiple sites) and maybe space to space. Launch platform being considered is a Space Shuttle DTO package. The ISS location could be one of the JEM External Facility sites which would accomodate an experimental package with these charateritics: Mass = 550 KG ; Volume = 1.5 m^3 ; Power = 3-6 KW @ 120 volts ; Thermal = 3-6 KW ; Data Rate = 43 Mbbp. Ground sites may include rectenna farm and large dish receiver. The team is trying to establish a demo concept baseline by Sept.

  88. Edawg said

    ignore my last comment,i dont know how you guys manage to get alcohol and electronics to go along with each other..We all want SSP to be a political issue.But we dont want to get involved in party politics for fear of dividing the space groups(lol).We have a National Security reason to seek alternative forums of energy and well that is the biggest stick out there right now.The Pentagon is military organization and cannot get involved in politics but if our National security is at risk why cant the big stick be used on the media!? The USAF did a great job on some of there new recruiting commercials,everything depends on our satellites then boom! Great PR stuff..its very hard to make an argument against that

  89. Robert said

    Wishing you success on the demo, Bill Rothschild. Sounds aggressive and it’s great news.

  90. Neil Cox said

    The following is a revised version of the idea, I just posted at Your comments may prove valuable in the unlikely event that the judges want more info: A free flying platform shaped like an equilateral hexigon 200 feet on each edge is supported by six hydrogen filled balloons attached by 330 feet of ribbon (600 feet at the three alternating corners of the platform) A 7th smaller ballon partially fills the center gap and is attached near the center. Two flying electric generators = FEG are attached by 3 miles of tether. The two FEGs supply electricity to the equipment on the platform, keep the platform reasonably level, and allow minor movement of the platform with respect to the prevailing wind. The platform flies at 100,000 feet, or higher, depending on the weight of the platform and it’s equipment. Development of CNT = carbon nano tubes with great specs, will be helpful, but almost that high is practical with existing materials.
    A 35 foot flat mirror which can be warped to slightly concave, will hang from a 300 foot ribbon under the center of the platform. The mirror will be aimed by thrusters similar to those used to control the attitude of the space shuttle. Alternately, the two FEG can aim the mirror. The mirror reflects sunlight through a hole in the clouds to existing large solar sites up to about 50 miles away.
    If this is done from LEO = low Earth orbit, I believe the minimum illuminated spot size is larger than any existing solar energy receiving sites. An altitude of 100,000 feet, however, does provide near optimum spot size for existing large solar sites, which will produce more power when the beam is available. A large fleet of similar flying platforms are needed to increase the power output of solar sites throughout the Northern hemisphere. This is why I suggested hydrogen, instead of helium, as the world likely cannot produce enough helium for a large fleet. Fire and explosion hazard is near zero above about 20,000 feet. Hot air balloons are an alternative, but the 100,000 feet may not be practical until we have CNT or equivalent with great specs.
    When no solar site is within range, crops can be warmed slightly by the beam. Cities and ships at sea warmed, and cloudy days made a bit brighter. A few minutes of extra sunlight can be provided near sunset and sunrise. I believe the beam will be in demand as soon as it becomes available.
    If a million platforms are flying, the Earth will be cooled perhaps 0.001 degrees f, but tangled FEG tethers should be rare even if little effort is made to prevent tangling. The platform should be white on top to reflect sunlight toward the balloons and space. Warming the balloons will allow a slightly higher altitude.
    The 35 foot mirrors were built for Star Wars = Strategic Defense Initive almost two decades ago and may be presently available as surplus items. Some additional scale up is likely practical, but large numbers of platforms are likely better to provide near constant power at each solar receiving site.
    More details: The angle of the sun and the solar site will occasionally be unfavorable, and the balloons will occasionally shade the mirror (at low latitudes in June and early July) If a second platform is within a few miles a double bounce may be practical, or the mirrors can heat the balloons allowing a slightly higher altitude, which will sometimes be desirable. The platforms can be used to help predict the weather, other science, as cell phone towers and if sufficient power is available from the FEGs, radio, radar, SSP and TV towers. Vacationers may find a few days living on a platform exciting.
    The FEG tethers need to be several miles long to get a wind speed different from the platform speed, otherwise neither lift, nor electricity are produced. See
    Lift off from the ground will require a day with little wind, but wind gusts are rare above about 20,000 feet. The steady wind does not apply mechanical stress to a free flying structure.
    Free flying balloons launched North of the Equator, circle the Earth several times and can be recovered near the Arctic Circle. This cheap energy will bring opportunities to property near the Arctic Circle. I suggest that the beam be sent at no cost to anyone who energizes a transmitter with proper code, priority being given to those who are willing to pay for the priority code.
    The Southern hemisphere will be impractical due to the high cost of recovery in Antarctica. Neil

  91. Neil Cox said

    Some people will perceive bad effects, but the balloons and platform will reflect many times more energy back into space than the beam delivers to the surface. If there are no signals, requesting the beam, the beam will also be sent upward into space.
    GPS on each platform and a worldwide computer network, will triangulate the radio signal on subsequent passes of all the platforms, so as to improve the accuracy, and appropriatness of the illuminated spot, at each solar solar site, ie, the size of the guard band will become important for multiple beams from larger mirrors illuminating a site.
    From a distance of 18 miles = 100,000 feet or more, the intensity of the beam will be much less than direct sunlight, unless the mirror is much larger than 35 feet in diameter.
    Balloon tenders, similar to the U2 spy plane (ceiling 100,000 feet) will be needed to insure that balloons do not land before they reach the Arctic Circle. I believe attitude thrusters, similar to the space shuttle, on the airplane can allow the aircraft to dock with the balloon platform. The repairs will need to be completed quickly as the platform will descend due to the weight of the airplane. Neil

  92. Edawg said

    I wonder if you can use an airship as a launch platform?Kinda like a flying aircraft carrier you used to see in comic books.It could halve mass fractions or you could just build a couple high altitude carrier aircraft for TSTO

  93. Edawg said

    I stress the point that next generation space systems need to be modular.Fewer but better is not the best route to go for National Security purposes.Because if something “breaks” you loose a massive capability.But if you have many cheap systems its harder to put a dent in things.

  94. Paul Roberts said

    Very interested in the proposed ISS DTO for wireless power transmission. Can Bill Rothschild please contact me at:


    This is a serious enquiry from a space industry company looking for details on this DTO and contacts at NASA for this DTO.

    Thanks a bunch,

    Paul Roberts
    Sr. Project Engineer

  95. stan said

    We are already on a planet that gets plenty of solar energy all we have to do is,take better care of it.And if we do the air will get cleaner and allow more energy in! What are we waiting for?A new invention? Lets use what we have.

  96. Paul said

    We should all be looking at the environment and what we can do to help the situation. It’s great that you are promoting solar energy and its be benefits.
    Keep up the good work

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