Space-Based Solar Power

a public discussion sponsored by the Space Frontier Foundation

“How to Build a Space Solar Power System”

Posted by Coyote on July 22, 2007

My friend Darel Preble sent a comment to a previous posting that included a paper entitled “How to Build a Space Solar Power System.”

I encourage you to read the paper available at the link above. Does it describe a viable way forward?

About these ads

66 Responses to ““How to Build a Space Solar Power System””

  1. Des Emery said

    Hi, Coyote — ‘How to Build a SSPS” is a good read. I wonder about the comparison of this endeavour to the expansion of the railroads, however. Then, the vision superseded the practicality of the project. Now, the vision is clouded by the indifference of the government, the intricacy of the law (which could tie up progress in the courts, sorting through all the items of various precedence, who deserves which dispensation, and the other legal considerations which can be snatched out of then air), opposition – overt or covert – from entrenched insiders (Big Oil, Big Agriculture [ethanol], the Military-Industrial people who would rather spend the money on Moon-based missiles, et al). I believe the vision calls for much more international co-operation, the UN or one of its branches, and a belief in the absolute necessity of getting a foothold in space, as strong as the old belief that the railroad must be built somehow, to get a foothold on the West Coast. But then, I acknowledge that talk, especially mine, is cheap.

  2. Does it describe a viable way forward?

    Actually, no, it doesn’t. It doesn’t describe anything at all. Space solar power development requires technology, not politics or the nuances of corporate structure.

    Perhaps the biggest mistake that most space solar power advocates make is that anything delivered to orbit requires a vehicle (for instance, a rocket) as a fundamental prerequisite for delivery, and the mass fractions are such that the rocket itself dominates over the payload in the rocket equation. For all practical purposes the rocket is the payload. With conventional rocket technology being what it is today, if the solar power satellite isn’t integrated directly into the rocket body, the whole concept is a non starter.

    On the other hand, if the solar power happens to be integrated into the rocket body, it’s a win-win-win-win-win situation. You get great advances in rocket technology (necessary to increase the payload fractions) you get your solar power satellite (by merely clustering up the rocket bodies) and you get your space colonization technology (the rocket body consists of large oxygen and hydrogen tanks and their associated pressurization systems), which for all practical purposes are space hotels, and furthermore, there is no lack of power for this infrastructure, since the solar power satellite happens to be integrated into the structure and no exotic microwave beaming technology is required at all in the near term. For standard single stage to orbit, space shuttle main engine simulations, we also routinely get over 2 percent residual fuel remaining, a substantial addition to the payload fraction, which is easily converted directly into heat, electricity and water, or reserved as oxygen and propellant, primary orbital consumables.

    The key to this fundamental concept of payload mass fraction enhancement, is the ability to return high performance cryogenic engines from orbit, to the surface of the Earth, intact. A mere cursory examination of rocket technology identifies a key necessary rocket component ideally suited for this task – the nose cone (also known as the payload aeroshield).

    Large scale development of earth orbit is like climbing Mount Everest. If you aren’t leveraging every aspect of classical rocket technology in every possible manner, you will fail to summit.

    Thus far, the United States has failed to summit, as evidenced by the recent discarding of a large ammonia tank from the space station. This is a perfect example of how NOT to develop space. This is the kind of behavior that must change before the United States will have the kind of technological maturity necessary to summit the very deep gravity well in which Earth sits.

  3. niminic said

    While this is not necessarily a direct reply to the aforementioned essay, it does address some technical issues I’ve pondered recently. Given the relative inefficiency per sq. ft of modern conventional solar panels, it seems equally inefficient to place the large arrays needed to produce substantial power levels, worth sending back to Earth (regardless of the means used to get it there). However, with the extreme temperature differences present in space between sun and shade, wouldn’t it be possible to utilize a sort of “heat-pump” system to transfer energy as heat via an inert gas/fluid in a closed system? To clarify, unlike the heat pumps used to cool and heat homes, this iteration would be more akin to a low-mass turbine driven by the movements of said medium. This medium could perhaps consist of helium, liquid when on the cold side of a spacecraft, and high pressure gas when heated by the suns rays.
    I’ll be honest, I’m no engineer. Just a radio repair technician with an interest in space development. I don’t know for sure if the principles I’m descibing could be utilized effectively in a space environment. But I believe that this system, or one similar, operating in concert with conventional solar cells could indeed produce large amounts of power for a relatively small footprint in space. Should the technology prove useful, it could even perhaps be adapted for surface use on future moon missions. I’m interested to hear what anyone thinks of this idea.

  4. Edawg said

    Look good to me even though Im not a lawyer.What about University co-op? UCF has a CATS program…I would equate the building up of earth orbit infrastructure to the building of the the highways or the railroads.If you build it traffic will flow =)

  5. Marcos Stefanakopolus said

    In my opinion, developing large-scale Space Solar is key to providing a liveable world for humanity’s masses in the century to come. The math shows that really ludicrous amounts of energy are available, and harvestable, up in space. We should be tapping that, rather than tapping oil fields of ever-decreasing quality.

    However, I have to disagree with the methods suggested by the paper linked above. Some while back I was fortunate to attend a lecture by Bryan Laubscher of LANL on the Space Elevator concept. He made an extremely compelling case that Space Solar is really only viable in the context of Space Elevator operations. It was almost an off-hand comment during his lecture, but he remarked that when he asked an MBA to analyze the economics of Space Solar, the analysis showed that with traditional rocket launch capabilities, you could do Space Solar but the payback time would be 26 years. Not viable as a business model. Conversely, he found that the payback time was only 7 years with a Space Elevator at your disposal, and that INCLUDED the cost of building the elevator itself!

    I’m not an MBA, so I can’t re-do that analysis myself, but in my opinion no analysis of Space Solar can be considered truly rigorous and reliable without considering a variety of launch systems, Space Elevator included. Talk to Mr. Laubscher. He knows his stuff.

  6. Much of the problem stems from how to get the money to launch say, 1000 rockets into space in a short period of time, so that you could get right into assembling your device in space. I propose simply launching from a LOT more places around the USA for example. I would personally pay to see a launch close to home, perhaps in return I’d get some portion of the proceeds as a discount on future power consumption. With 400 large cities in the USA and each easily able to generate around 10,000 ticket sales of $100 each, that’s 400 million dollars. Now if you can just figure out how to get 400 simple vehicles into space for say, 800 million, assuming a government matching subsidy…

  7. Mark Ellis said

    for all its ability to be an interesting idea, space based solar is just not a good one. energy and economics are inseperable. even if payload costs dropped to $100/kg, solar cells are expensive, fragile, and inefficient. the funding required to get it up there is, well, astronomical. and say the funding was there, how do you get the power back home where its needed? remember there are transmission losses. so there are funds required for delivery on top of just geting the array, to my knowledge, such a delivier system is not in existance. Take the same solar cells and start roofing homes and businesses and you decrese your transmission losses entirely, cut the need to invent delivery infrastructure, and provide the ability to grow the power grid without huge government expendatures. is space solar a horrible idea, no, but only when we have exhausted cheaper ways of meeting our energy needs, built a space elevator and exhausted nuclear, wind, and wave technologies should we embark on such an expensive proposal.

  8. pvkv said

    I guess the obvious answer is to combine the solar power array with a space elevator. The array could supply power to the elevator, making it cost effective for both the government and business. Surplus power would be fed into the power grid. Perhaps it could be used to provide power to an electric highway system.

  9. moontube said

    I agree that Thomas Lee Elifritz has identified a major obstacle to the construction of solar power satellites, namely the payload mass fraction of rockets. We should be looking for other methods of throwing stuff into GSO. One possibility is an electromagnetic railgun. Another is Robert Bussard’s Polywell electrostatic confinement fusion powerplant. Since solar power satellites need square kilometers of collecting area, Elifritz idea of using expended rocket bodies does not do the job.

  10. Preventing Human Extinction said

    By far, the most effective way to “Build a Space Solar Power System” is to first tackle the currently theoretical space elevator. Observe the efficiency of the possible technologies that could catalyze our trek into space. As of yet, the space elevator is the quickest and most effective way to haul our humanity and its technology into space, including the development of this space solar power system. Here are the reasons why:

    1) It is feasible: Once it is complete the amount of energy needed to move supplies into space in large quantities is a very small fraction of what modern rockets use. Furthermore, utilizing the forces of our earth’s gravity, counter-weights much smaller than the load being pulled up will do the job countless times.

    2) Making an elevator is a one-time event (unlike rocketry), and you can build many of them. This means you could run power cables along them to supply power to many parts of the world.

    3) Having a permanent link for power to run will allow the use of high Tc superconductors meaning very little loss in energy across the cable; the space elevator allows for many augmentations and not yet recognized feats in efficiency technology. So called “wireless electricity” technologies will only provide a fraction of the electricity that wired equivalents do. Lasers could also be used, but lasers will still only function at a fraction of the efficiency as a solid link (not to mention all of the other faults with the laser phenomena).

    This is only a brief summary an idea, and I have much more. Team Leaders, please email me if you would like more.

  11. For those who wish to alter the errors of humanity for its benefit, I applaud thee. If the powers that be at the beguinning of the so called ‘industrial revolution’ foresaw the consequences humanity is facing now, the ever mortal greed of mind would have subsided even if slightly to try and make our children, our children’s children and the following generations suffer less the burden of pain shared with the only planet that sustains us all.

    My dear friends, there was a man born July 10, 1856. He came to this earth for the benefit of humanity, but those who foresaw green paper in abundance failed to see beyond that. Any environmental issues humanity have been highlighting and discussing for over one hundred years would have been nonexistent if only the man known as Nikola Tesla had been free to lead the way forward.

    Without red blood, man cannot survive the physical life. Without black blood, Earth cannot sustain its physical life. Just think about the meaning and the importance of that meaning. Lessons will always be learned, but humanity takes its time in doing so and therefore too little to late is the consistent pattern.

    Some of us know more than others of what Nikola Tesla (and others like him) was capable of and if we think of any form of energy we take for granted today, then some of us might conclude we have been living a primitive existence all this time. I observe our present form of wasted energy in disbelief which cannot be measured in words alone.

    Humanity has been looking for ways to replace its wrongs. It is of course a good thing but never the less a small measure of compensation as we are taking the long way around to achieve what people like Nikola Tesla knew already but even went beyond what our imagination could master.

    Today as we raise green issues…it is never too late but also never soon enough.

    Regards

    James Segwell

  12. lgroner said

    Technologies like space solar and space tethers can be synergistic.

    Both need not be in final state to be useful.

    Space solar can be useful even if not photovoltaic. Aluminized mylar shaped by inflatable tubes can form large reflective optical devices with very small mass. Directed heat and light can be valuable without passing through an intermediate electrical power form. Warming a region of a few hundred square kilometers even a few degrees can be valuable in saving crops from frost, reducing space heating needs or keeping harbors ice free longer.

    Space tethers need not reach from the surface to geosynchronous orbital altitudes. Imagine a tether cable rotating about its own center of gravity. The tether’s center of gravity in turn is in orbit around the earth. A cable end is, at times, both lower and slower than the center of gravity and, at other times, both higher and faster. A vehicle that rendezvous with the cable end at the former time, hangs on and departs at the later time gains energy from the cable that can be used to reach higher orbits or escape speed. Of course the cable loses energy in this transaction. Ion engines powered by solar electric could work to replace this energy.

    While cheaper means of moving mass from Earth to orbit is desirable, it is more energy efficient to get materials from sources in gravitational wells less deep than earth . Such sources include the moon or asteroids. Space mining would be much more economical if most of the work was done by robots not needing expensive life support and man rated safety regimes.

    The program outlined above will take decades but its initial steps are within our current capabilities. Eventually we could outsource much of our electrical power production to orbit. In the process we would be creating an industrial and mining infrastructure in space that could fuel the exploration of the rest of the solar system.

  13. JOSHUA. said

    I HAVE SEEN THIS WEBSITE AND ITS QUESTION(S)…..

    I SHALL THINK ABOUT IT, AND REPLY AT A LATER DATE.

    THANKS YOU.

    JOSHUA.

  14. Layman Jim said

    Here’s my take at how to build a space based solar power collector. Make a space mylar space blimp, where one half is silver and parabolic, and the other half is transparent. Inflate and place a high efficiency solar cell designed for multiple suns at the focus on the transparent side. This design should be very lightweight and easy to assemble with few parts.

  15. Ramael S. said

    Why not build a solar power system that uses the Suns heat to move like the planets do? Have a spinning core made out of nickel to generate magnetic waves that can be used for the movement of your spaceship. The core will work from heat energy to spin in the same way that the planets use the Suns heart to spin. A magnetic wave will be generated by the core which will allow one to “pull” yourself through space instead of “pushing” yourself with booster engines like modern Rockets do. Magnetism is the key.

  16. Michael Macri said

    I recently read an article on msnbc about a method of “wireless” power transfer using magnetic fields being developed by MIT. From what I have read this system is only 30% efficient and would need a great deal of funding and research before it could be applied. This technology further developed could provide a viable method for delivering the power generated by orbiting collectors to earth without having to rely on rockets.

  17. highflyer12 said

    Not having marinated in all the info on this discussion, I just put forward one simple/Grand idea (maybe it has already been discounted)

    put satellites in Mercury’s orbit, and beam power to Earth geosynch (or Lagrange point) relays for transmittion to Earth.

    The big problem collecting near Earth is the surface has to be very large to be effective, thus requiring MANY rockets. Instead, if the collectors were in solar orbit at Mercury’s distance, it could access much more concentrated solar energy, while never casting a shadow on Earth (but maybe with Global warming, that is precisely what we need to do ;)

    May this is actually more feasible (cost/benefit) than what was proposed above…

  18. Sergey Kurdakov said

    How about using http://www.launchpnt.com/Space_Launch.32.0.html for structural parts launch?

  19. Steve said

    From my understanding, the challange is to get the energy from where it is collected to where it is to be used. I would think electrolysis of water carried into space and the transport of H2 back would be a safe and effective method.

  20. Mr. Foo via Slashdot said

    The solar PV array IS the space elevator!

    I can’t believe I’m the first one to get this point out, but I’m glad to have the opportunity.

    I believe that this type of corporation makes plenty of sense for precisely the reasons that were laid out in the PDF. There is already historical precdendence for this sort of endeavor and focusing on energy policy before space policy makes good political sense which is what you’ve got to do before you can get funding which is where it all has to begin.

    Arguing that the space elevator has to come first is really missing the point. The space elevator plans that Liftport put forward are cool and all but it’s a lot less likely to get funding than something that uses technologies we have here and now like thin film solar which addresses the hot button political topic of energy and, by extension, national security.

    Politically, this stands a far greater chance of recieving funding than the Liftoport version of the space elevator. But it doesn’t exclude the space elevator concept at all. In fact, it contains a version of the same concept by design.

    So to get back to my lead-in.

    Think for a second about this situation. You’ve got a great big PV solar array already in orbit beaming concentrated energy back to the surface of the earth from orbit. Now, take the gerund “beaming” and think if it as the noun “beam” –as in a steel I-beam for instance. Or like, you know, as in the balance beam you may have wobbled across in elementary school.

    Ah hah! Yes, that’s right. A beam can be a form of transportation. Yes indeed. Rather than needing to haul fuel tanks into orbit along with each and every additional shipments of thin film PV, all you really need is just enough in orbit to create a beam powerful enough to send a vehicle up the beam utilizing the beam’s own large quantities of energy and acting upon the atmosphere at lower elevations and perhaps reacting with scavenged fuel from the upper atmosphere at the final stages.

    You no longer need a conventional rocket when you have a beam of say several hundred megawatts of concentrated microwave energy available throughout the entire journey. And even higher power densities could be achieved temporarily during launches using special made capacitors or superconductors which are potentially much more effectively operated in the environment of space and have been tested aboard the shuttle. These are existing technologies that make the idea of microwave beam propulsion even more attractive since it is not even necessary to have a base load powerful enough to perform the launch, you just need to sustain a single beam of sufficient power for enough time to allow subsequent deliveries and the result is essentially both solar power from space AND a massive reduction in the cost of delivering payload into orbit.

    So, the corporation’s charter should be re-written to expressly include the intention that only enough funding will be required to create a beam powerful enough to fuel a supply vessle which will carry the subsequent materials into orbit. Once that point is reached, the project should become quite profitable indeed.

    And this is the real reason it will be difficult to get funding for this idea. Any plan concerning energy policy that has the potential to suddenly escalate and proliferate massively after a certain amount of seed money is invested is certainly going to raise concerns among the various vested interests. Just getting the first few hundred megawatts of solar in orbit could, in fact, be a very disruptive technology.

  21. Leland Christensen said

    Photovoltaics has not matured enough to be a total solution. However, there are other issues to take advantage of in space, i.e. the ratio of hot to cold. Sun shining on object makes object hot. Coldness of space makes shaded object cold. Harnessing energy from the differences, elementary (even I can conceive of several methods not even considering new technologies). One that comes to mind: focused sun rays (parabolic mirrors) on heating element creating steam pressure (sorry, you’ll have to import some type of liquid for the steam creation). After turbine generates power from steam, vent steam into cold chamber, collect condensates, push through the cycle again. This system doesn’t have to be as bulky as it sounds, and as I undestand it, steam has always been able to pack a powerful punch. (your train examples forced my mind along the same track, pun intended)

  22. Coyote said

    All, thanks for joining in! Here are replies to some comments:

    Thomas Lee Elifritz: Rocket bodies as part of the integrated payload. I hadn’t thought of that. I was sort of hoping that we’d be using reliable, rapidly reusable spaceplanes by 2030 when the big construction will likely start. If we have to use expendables, then using the rocket bodies as part of a structure sounds like a good idea…it will depend on our design.

    Niminic: The use of “heat pumps” is a concept commonly referred to as “solar dynamic.” This is part of our trade space…photovoltaic, or solar dynamic. Photovoltaic appears to be the most popular, or at least the best known. We will be assessing both of these techniques.

    Marcos Stefanakopolus: Your vision is commendable. I suspect you are right. If I can do space-based solar power then I have built the infrastructure to make several other ventures into space much more viable! The idea of a space elevator comes up over, and over. By itself, the space elevator is an enormous project that will take a sizable number of lifts, on-orbit assembly, and maintenance. I agree that it makes the use of suborbital rockets more viable…and they are far more likely to be reusable because they do not suffer the thermal weakening that occurs in the thermal environment of 17,500 mph.

    Mark Ellis: I share your enthusiasm to capitalize on the cheapest clean power everywhere. But I also need a source of power that can be delivered anywhere in the world in a matter of minutes. If disaster strikes somewhere and puts down other forms of clean energy I need something to pick up the slack. I can do with space-based solar power. Space-based solar power becomes a gap filler. A couple of years ago when the California power grid was overwhelmed, a broadcast from a few satellites could have carried the load.

    Preventing Human Extinction: (I like your moniker) Yea…the space elevator. Man, that is a hard one. I have never seen an optimistic build-plan for one.

    Layman Jim: I like the inflatable idea. We’ll have to think that one through

    highflyer12: Mercury orbit…I bet the power path loss from 80,000,000 miles would be severe.

    Leland Christensen: There are pros and cons with photovoltaics and solar dynamic methods. We need to look at that more closely in the decades ahead.

  23. Mr. Foo via Slashdot said

    Hey, Coyote, where’s the love for Mr. Foo?

    I know I’m being a needy attention seeker here, but I want to make sure this point was made clearly. Obviously the concept of microwave propulsion is not my own original thinking. I’m sure I’ve read many approaches to it from many sources over the years, but I want to make sure this point is being made clearly here because I’m not seeing this in any of the other comments and I think it’s really a significant point.

    So, I real quick just did a Google on microwave propulsion and I came up with tens of thousands of possibilities, but I figured I would bring one here into the discussion to make it clear that this is not just some off the wall speculation.

    Therefore, allow me to quote a few succinct paragraphs from this site that came up early in the Google returns on the phrase “microwave propulsion”.

    Begin quote:

    The microwave light craft is equipped with two powerful magnets and three types of propulsion engines. Large number of antennas, built on the top of the craft, receives microwaves and converts it into electricity required for launching. The electricity produced ionizes the air and propels the craft forward.

    Upon reaching a high altitude the light craft tilts sideways. Part of the microwave power reflected from the front of the ship is used to heat the air. This allows the spacecraft to cut through the air up to 25 times faster with respect to the speed of sound. The other half is converted into electricity by the receiving antenna. This electricity produced help in energizing the engines, which help in accelerating air around the craft.

    Nasa researchers are working to develop a system that relies on microwaves beamed either from satellite or from a fixed point on earth. Their goal is to transport payloads and people into the low earth orbit for approximately about $100 per pound. This cost is roughly 1 percent of the total cost of launching the same payload with the help of a space shuttle.
    End Quote

    Quote source link
    http://library.thinkquest.org/03oct/02144/propulsion/microcons.htm

    Of course that’s just one of many concepts that use beamed energy. Some even use the term “light craft” to refer to such vehicles. Nasa’s own web sites are filled with references to variations on this technology. As suggested in the above quote, there could even be more than one beam. One from above and one or more from the ground could also be used.

    Inertial confinement of fusion targets is another technique that gets attention as you browse through the hits on Google. While ignition has not been achieved using inertial confinement of fuel pellets, it has long been possible to “burn” a very lightweight fusion pellet using dense external sources of energy. Fusion pellets are interesting because, while not exactly household items, they are fairly conventional and well studied from a science standpoint and they represent a very lightweight fuel source that would operate to produce thrust regardless of atmospheric conditions as long as significant external sources of power were available. Just because sustained fusion ignition remains ellusive as a practical source of commodity electrical power, there is no reason to think that inertial confinement does not work. Quite to the contrary, if efficient operation is not the paramount goal, the technique of using inertial confinement is still a way to produce significant amounts of thrust for a vessle once it is outside the Earth’s atmosphere.

    Or not. How would I know? Right. But the point stands that there are many concepts for using external beamed energy for transportation into orbit and I really want to emphasize this point because it has everything to do with the economics of solar energy in space and it is also important for the people who keep insisting on the primacy of the space elevator to see that these are not really separate issues.

  24. spacestandardsguy said

    A major part of the systems engineering technical base needs to be the standards that will support the application. This goes for all parts of any functional and operational breakdown. So launch, structures, command and control, – everything! needs a baseline. If you have a good tech baseline (my sugestion is working from international standards such as ISO’s TC20/SC13 and SC 14 and CCSDS) you can identify your technical shortfalls in establishe, open technology. This will limit your NRE costs and jump start your NPV.
    Some folks invest to make a buck. Some invest to save a buck. Some invest because they need the capability – the infrastructure – to grow in other areas. An SSP business model needs to target the market and show value to that market’s objective. Use the value equation and value propsition to really reach those who can and will fund SSP.

  25. Chris said

    Plastic Solar Cells technology is immature, but it does offer the potential to significantly reduce the mass requirements for both the photovoltaics and the supporting structure. The current record for efficiency is 6.5 percent, but that should improve over time. If we assume that efficiency can be raised to 15 percent by 2012, then rolls of plastic solar cells could be launched into orbit. A very large surface of photovoltaics cells could be launched on a single rocket.

  26. S.Gaber said

    First, let me say that I am not a Luddite. I heartily embrace the space program and all its goals and ambitions. But a number of issues must be taken into account.

    Solar energy beamed from orbit is a very interesting concept, but it begs the question: Why go to all that trouble and expense, when you could use that money by putting photovltaics and solar hot water on every house and building in the USA and maybe the world? While a laudable engineering accomplishment, it seems a very high-tech and expensive possible solution to a problem easily (comparatively) solvable with available technology. If every house or cluster of buildings were to generate its own power and heat its own water, control would be taken out of the hands of utilities and governemnts. Control would be given to individual citizens and civic groups. This is the sort of thing that governments and corprations hate. If a sizable number of indivuals opted out of the electrical grid, enough to impact utility profits, there would be pressure for governments to levy large taxes on indivudual efforts to provide power from non-regulated sources.

    Although not dorectly related to the topic at hand, I think there are other illustrative examples of the same kind of thinking. The last issue of Popular Science had as its central theme a series of ideas about how to improve the earth and its environment with some really ingenious concepts. But most of the goals of these concepts could be accomplished by adopting simple low-tech methods and attitude changes on a global scale. For example, using technolgy to defuse or prevent hurricanes might have unforeseen consequences. Hurricanes are the earth’s way of getting rid of excess heat. Eliminating them might be a good short-term solution for saving lives and property, but what would be the longer-term effects on the global climate? Why not put efforts into reducing global warming in the first place?

    One must consider other possible implications of beaming hundreds of millions of watts of microwave enrgy into the atmosphere. Would it affect the temperature of the atmosphere on a long-term basis? What wouold the efficiency for such a system be? If power losses through cables are taken into consideration, how much power would be lost in beaming it from orbit, through nearly a hundred miles of atmosphere to its destination? What about the health effects of all this microwave energy fluxing around the world?

    What about the security risks? This is also true of the Space Elevator. We could not provide adequate security to save two of the most important structures in the world in one of the world’s foremost cities, by a rag-tag collection of fanatics. How could we hope to protect a space elevator and its conncetion to the ground from attacks by land, sea or air? Or an orbital power station from anti-satellite missiles?

    I pose these questions as points for discussion and consideration only. Personally, I think a space elevator would be the best way to provide transportation to orbit. If the above technoiloogical, environmental and economic problems could be solved, attaching a solar power beaming facility to the space elevator could double its utility for mankind.

  27. Apocalypse said

    What about converting the solar power to microwaves and beaming them down from a geo-stationary orbit?

  28. Igor said

    Why not to make the Sun on the Earth?

    There is a wise man, W. Bussard, who goes after it. Support you all that great scientist. Don’t discuss here an obsolete solar power outside the earth, if you can have the solar power now, here, on th earth. Support W. Bussard (just google arround on Bussard)

  29. Luna-tic&rockrat said

    I wonder if in puting all options on the table your study will consider the use of NTR’s (Nuclear Thermal Rockets) in the HLLV

    nuclearspace.com
    has a series of pages dealing with a gas core NTR based “liberty Ship” with a fairly conservitive base figure of eight times the cargo capacity of the Saturn V for the same weight at launch.
    They figured that using Hydrogen reaction mass and a pacific sea launch the use of a nuclear spacecraft could be made clean enough for all but the most “green” objections.

    as for the SPS side I hope that your study looks at using a demo SPS to beam power for a LEO to GEO electric engine tug.

    another Luna-tic & rock rat

  30. Edawg said

    NTR is the way to go.Who the wants to spend a year going to Mars instead of a couple of weeks? If they never cancled NERVA we would pry be having a manned mission to Trition right now. Hopefully the govt get moving before the EU and Russia form their partnership. Ruskies with an extra 16 billion or so for space…Bet that would cause another congressional hearing

  31. live2scan said

    I emphasised JP Aerospace’s model in an earlier post as an effective way to build a Powersat system without having to relie on lunar or asteroid based materials processing in large part because it makes use of EXISTING technologies. With much of our manufacturing industry headed offshore, boosting some of our remaining capacity would seem to be a wise use of our resources.
    The U.S. is still a leader in the electronics industry, more demand for PV cells and RF power transmission systems would help to maintain that situation and provide an incentive for those companies to expand. Boeing and GE to name a couple, might be recruited as allies to help move this process along.
    The Dark Sky Station concept could be monetized almost from the start, it might even pay for most of the cost of building the rest of the system. A small DSS could be a broadcast platform, MILTITARY recon platform, weather and earth resources monitoring site at a cost far below that of orbiting hardware. A larger one might be a tourist destination or an alternative to a mountaintop or deep space as a site for astronomical observatories. Imagine the resolving power of a scope at the edge of space that isn’t limited in size by launch vehicle considerations or the need to protect it from the weather.
    A large DSS could also be a part of the power transmission system a rectenna could hang for miles beneath such a platform to allow power to be retransmitted around the globe. A foil mirror hung in a similar fashion could be used to augment insolation in places( Fairbanks might have the same year round average insolation as Cairo with such a system).
    What I’m trying to say is don’t just look at the end product. All SSPS systems are not equally valuable or as easy to get implemented. The more infrastructure that can be utilized early on for other purposes the more of the existing political power structure you can co-opt for your(SSPS) purposes and the easier it gets to show A PROFIT.
    A DSS IS the high ground and we need to control it and not have to take it back later

  32. Christine said

    Is this the same JP Aerospace that thinks they can use an ion engine strapped to an airship to get to orbit? Seriously, [think] about gravity losses.

  33. Christine said

    If we assume that efficiency can be raised to 15 percent by 2012, then rolls of plastic solar cells could be launched into orbit.

    Or stapled onto your roof. Who knows, maybe by 2012 a delta IV will be cheaper than a staple gun?

  34. Gary Walston said

    As neither a structures engineer or physicist, I have to ask the question if the space elevator concept has had a rigorous engineering feasibility review. From a lay perspective, it seems structurally difficult, if not impossible, to create an elevator structure that wouldn’t collapse under its own weight or tolerate the weather stresses involved. How massive would the base have to be to support the stress of something in GSO?

  35. Dan Lantz said

    Gary #34:

    Glad to see interest! Space Elevator is actually a geosync satellite that has a center of mass in orbit, with long hanging tension structure barely hooked to Earth at tip. Counterweight is beyond center of mass. Tension is much easier than support from below, but still takes nanotube diamond-like strength. Build from captured comet Carbon and drop tip to Earth, rather than attempt to launch parts and then assemble.
    Related concept is rubber band shaped loop built in vacuum tube on ocean surface. Turn the loop at “ends” with magnetic force as if it were a particle beam. After loop exceeds orbital velocity, long middle sections will rise into space. Remove the tube where it is in space, and ride into orbit or faster towards other planets! Far out, man.

  36. Bogdan said

    I have read in Wikipedia about solar power: http://en.wikipedia.org/wiki/Solar_power and the peak irradiance at the equator looks quite good. The problem is that this decrease in the morning and evening when the requirement for energy is bigger and it totally lacks during the night. To solve this I suggest to use a geostationary satellite mirror, and use ground based photovoltaics. Of course both the mirror and the photovoltaic panels should be orientable. This would reduce the mass to be transported in space. Also I think that the ground facilities could be administrated by private companies.

  37. Joe Russo said

    I have three thoughts on this (actually more, but I will keep it to three)

    1. Comparisons: The history of how the rail road developed is a good reference point, or the example of satellites communications, however, I think part of the problem here is what the USA experienced with the Lunar Lander. When it was being developed, there was not enough comparison to help reduce the speculative time lines, etc. Now the space station is a closer example, and we did not wait for a space elevator and moon base to build it.

    2. International team building: I do agree that international team building is good, and also see that there are examples of government programs that came out great. The Postal Service, programs that supplement the public transportation system, government programs that saved American companies and manufacturers from going under, etc. Let us not discard the power of government and as the access of space becomes cheaper we can cut down our cost; I think we should try to make as many friends as possible even if they are people related to oil. Yes Coyote, this will be the last time I say it. There are all types of interesting things some of my associates are doing to reduce the cost. I believe we will see a big change in the next 5-10 years.

    3. The structure: I have already made my suggestions a few times on other topics, and according Coyote posting on July 26th I think he understands the good points. I do have one additional question, will it be cheaper to replace damaged mirrors or solar cells?

  38. John Lee said

    “The market of the elevator is much larger than needed to produce an extremely attractive business case. BP Solar stated at one point they would put up the money to build the first solar power sat if we built the elevator.”

    If you are interested in the Space Elevator as an enabler for SBSP, take a look at Brad Edward’s post #34 under “Scientific Challenges”. If BP Solar will put up the 1st Sat., then supporting the development of the Space Elevator should be considered as one route to reaching our goal.

    John

  39. Joe Russo said

    John

    Thank you so kindly for the quotation:

    “..BP Solar stated at one point they would put up the money to build the first solar power sat if we built the elevator…”

    This is great and good news. Have we received a commitment to this? Do we have to put off the construction of the solar power sat until the elevator is put up, constructed, and proven safe? etc. As I attempted to clarify before in another topic. If we jump on building a solar power structure, maybe it might bring more people to the table with more commitments. As I also like to clarify, I am not saying that things like space elevators are out; nor is it my position to judge.

    Now, I have a question, what does BP stand for and where is their financial resoruces going to in relationship to the war? I ask for I do not want to make an assumption. I will not be back on line untill the end of this week.

    See you

  40. John Lee said

    Joe-

    I don’t know the facts behind the quote; I was merely quoting
    from Brad’s post as mentioned above. I do know BP Solar stands for British Petroleum Solar.

    John

  41. Neil Cox said

    I think we can start engineering a demonstration Solar Power Satellite in LEO = low Earth Orbit, Perhaps 200 square meters of thin film photovoltaic cells which will make about 30,000 watts at about 100,000 volts. 20,000 laser diodes in series are on a separate platform connected to the power platform by about one kilometer of flexible power line. This allows the laser diodes to point and track many solar sites (one after the other) around the world, while the solar panels face the sun. As much as 8 kilowatts of light energy might be delivered to the larger solar sites, allowing the solar site to put about one extra kilowatt on the grid. Not impressive, but I think bigger than other nations are planing as a demonstration Solar Power Satellite. We still have a chance to be first, I think.
    I’m guessing a spot size as small as 8 square meters is practical, which is one kilowatt per square meter = 0.1 watt per square centimeter. Power density will be perhaps 0.04 watts per square centimeter, when the satellite is 30 degrees above the horizon, so there is a negligible health hazzard, if most of the energy misses the solar site. Solar site operators can turn on an inexpensive beacon if they want the beam from our SPS.
    Somewhat less than 100,000 volts is ok for such low power, but we need to practice very high voltage for high power solar satelites we may build later. We will want at least one receiving site optimized for the laser wave length. With good luck we may have better thin film photovoltaic panels and better laser diodes available, by launch time in 2012. The satellite can be in semipolar orbit so it passes over most of the nations of Earth. Is that a reasonable goal? Neil

  42. Neil Cox said

    The space elevator, the Moon base and the Moon elevator though lunar L1 likely will not be available until 2032, so we should not wait to produce the demonstration SPS = SBPS. When the space elevator is available we will have 20 years of experience building puny SPS = SBPS. This will allow us to build a much better SPS = SBPS with the help of the space elevator than we could without the experience.
    I think we should assume British petroleum will put up the money for the second SBSP, so we should proceed as quickly as practical with both the Space Elevator and the first SBSP.
    Building a demostation rotating bolo in low Earth orbit will help advance technology related to the space elevator. The bolo should have a Brad Edwards type climber on it to make repairs to the bolo and to advance climber technology. I have posted frequently as Neil on the forums at http://www.space.com
    I think damaged mirors can be repaired. Part of the solar cell array needs to be de-energised to replace bad cells. Replacing open circited solar cells and other open components needs some serious attention.
    Post 36 The difficulty with a solar mirror at GEO = GSO altitude is the Sun is not a point sourse of light, so the beam would be as wide as Earth, with negligible power density. The throw of a solar mirror must be much less than 36,000 kilometers: perhaps a solar miror from a balloon platform at a slant range of 36 kilometers would be useful. Does anyone think we can colminate sunlight so the sun beams are paralel before we reflect the light with a giant mirror? I suspect each laser diode needs it’s own optics to produce a sufficiently narrow beam from GEO altitude. Beam spreading may be a show stopper for nearly all applications exceeding ten kilometer beam length. Someone needs to access the very secret Star wars = Stratigic Defense Inititive data to determine the beam speading solutions and results. Neil
    JP Aerospase has made some erronious proposals in the past, but we can assume some of their new ideas have merit because many others have simular ideas.

  43. Neil Cox said

    Please forgive me for copy, paste and edit of Post #26 Gaber Says:
    July 26th, 2007 at 11:25 pm
    First, let me say that I am not a Luddite. I heartily embrace the space program and all its goals and ambitions. But a number of issues must be taken into account.

    Solar energy beamed from orbit is a very interesting concept, but it begs the question: Why go to all that trouble and expense, when you could use that money by putting photovltaics and solar hot water on every house and building in the USA and maybe the world? While a laudable engineering accomplishment, it seems a very high-tech and expensive possible solution to a problem easily (comparatively) solvable with available technology.
    Me: Dont forget we also need SBPS for military operations and disaster relief.
    Gaber: If every house or cluster of buildings were to generate its own power and heat its own water, control would be taken out of the hands of utilities and governemnts. Control would be given to individual citizens and civic groups.
    Me: This will work on selected roof tops, especially new construction which can be optimized for solar power = more than 1/2 of the roof area steep and facing South or South-West. Steerable roofs may even be practical to catch both early morning and late afternoon sunlight. Existing residentual roof are frequently shaded much of the day by trees which are removing carbon from our atmosphere. Commercial roofs are often flat and bristeling with air conditioner and refrigeration units which shade the panels especially in December when the Sun is low in the sky. For new construction roof overs with solar panels may be practical, but they will cause severe wind loading, requiring more costly construction of the entire building. Unfortunately some of the sunniest location get huricanes and/or tornadoes. The Southwest is typically thinly populated and thus there are few nearby customers for the electricity. The Northwest has cloud cover more than 1/2 of the time. We should fund super conductor research as it has potential for making long transmission lines practical.

    Gaber: Using technolgy to defuse or prevent hurricanes might have unforeseen consequences. Eliminating them might be a good short-term solution for saving lives and property, but what would be the longer-term effects on the global climate? Why not put efforts into reducing global warming?
    ME: Most efforts are ineffective or worse.

    Gaber: One must consider other possible implications of beaming hundreds of millions of watts of microwave enrgy into the atmosphere. Would it affect the temperature of the atmosphere on a long-term basis? Me Negligible. What wouold the efficiency for such a system be? About 10% If power losses through cables are taken into consideration, how much power would be lost in beaming it from orbit, through a hundred miles of atmosphere to its destination? Me: 10% for microwaves. 90% with heavy clouds for laser diodes. What about the health effects of all this microwave energy fluxing around the world?
    Me: negligible for the first 1000 gigawatts. Perhaps a problem if ten percent of human energy use comes from SBSP = SPS
    Gaber: What about the security risks? This is also true of the Space Elevator. We could not provide adequate security to save two of the most important structures in the world in one of the world’s foremost cities, by a rag-tag collection of fanatics. How could we hope to protect a space elevator and its conncetion to the ground from attacks by land, sea or air? Or an orbital power station from anti-satellite missiles?
    Me these are reasonable conserns also for our existing infra structure. Security will increase cost considerably.
    Gaber: I pose these questions as points for discussion and consideration only. Personally, I think a space elevator would be the best way to provide transportation to orbit.

  44. Neil Cox said

    I would think electrolysis of water carried into space and the transport of H2 back would be a safe and effective method.
    Me: Hydrogen could be transported back to Earth from an SBSP = SPS, but my guess is: far more costly than Laser diodes or microwave beam, even if we have an operational space Elevator
    Mr. Foo via Slashdot Says:
    July 26th, 2007 at 2:19 pm

    Arguing that the space elevator has to come first is really missing the point. The space elevator plans that Liftport put forward are cool and all but it’s a lot less likely to get funding than something that uses technologies we have here and now like thin film solar which addresses the hot button political topic of energy and, by extension, national security.

    You’ve got a great big PV solar array already in orbit beaming concentrated energy back to the surface of the earth from orbit.

    Ah hah! Yes, that’s right. A beam can be a form of transportation. Rather than needing to haul fuel tanks into orbit along with each and every additional shipments of thin film PV, all you really need is just enough in orbit to create a beam powerful enough to send a vehicle up the beam utilizing the beam’s own large quantities of energy.

    You no longer need a conventional rocket when you have a beam of say several hundred megawatts of concentrated microwave energy available throughout the entire journey. And even higher power densities could be achieved temporarily during launches using special made capacitors or superconductors which are potentially much more effectively operated in the environment of space and have been tested aboard the shuttle. These are existing technologies that make the idea of microwave beam propulsion even more attractive since it is not even necessary to have a base load powerful enough to perform the launch, you just need to sustain a single beam of sufficient power for enough time to allow subsequent deliveries and the result is essentially both solar power from space AND a massive reduction in the cost of delivering payload into orbit.
    Me: The main problem is coverting the microwave energy to vertical motion against gravity. Ion engines do this, but at present are inefficient and puny. Liftport hopes to use electric motors to squeze rollars thus friction to climb the space elevator ribbon. I agree a laser beam from a GEO = GSO can power the clinbers on the space elevator almost as efficiently as lasers on the face of Earth. Using both simultaniously would require two photovoltaic panels on the climber, thus reducing climber payload = one facing up, the other down. A down beam with a megawatt per square meter, would be dangerous to unprotected humans, so we would have to be very cocerned where the down beam would hit Earth if it misses the photovoltaic panel on the climber. This is much less of a concern for the up beam, but not a zero concern. Neil

  45. Neil Cox said

    Hi highflyer post #17 If we build a space elevator,it can throw a pay load to Mercury. The payload needs some deta V for midcourse correction, perfecting a sling shot manuver = gravity assist manuver around Mercury and to settle into Mercury L1 or L2. I don’t know which is best.
    To reach Earth from Mercury the SBSP beam traves 100 million to 200 million kilometers, so the SBSP beam spreading prevents practical power delivery to Earth, however the laser diode beam can assist in illuminating asteroids and comets which we have not found yet in the inner solar system, and the SBSP beam can help propel and help manuver solar sails, if we start using solar sails. An SBSP could possibly beam energy to human colonies at the poles of Mercury. The rest of Mercury is too hot for humans or robots that we can build now. You are correct, being closer to the sun reduces the size of the solar panel area by about 9 times. Neil

  46. Neil Cox said

    Post 29: Luna-tic&rockrat Says:
    July 30th, 2007 at 4:33 am
    I wonder if in puting all options on the table your study will consider the use of NTR’s (Nuclear Thermal Rockets) in the HLLV

    nuclearspace.com
    has a series of pages dealing with a gas core NTR based “liberty Ship” with a fairly conservitive base figure of eight times the cargo capacity of the Saturn V for the same weight at launch.
    They figured that using Hydrogen reaction mass and a pacific sea launch the use of a nuclear spacecraft could be made clean enough for all but the most “green” objections.
    Me: I’m afraid the number of most “green” people make nuclear power rocket bad PR closer than about 200 kilometers of Earth. If extensive use of NTR shortens the life expectancy of a billion humans, by one day on the average; is that OK? I’m not sure.
    LT%RR: as for the SPS side I hope that your study looks at using a demo SPS to beam power for a LEO to GEO electric engine tug.
    Me: It should be easy to turn the demo SPS (in LEO) to beam energy to other satellites and a space tug whenever one is in range. Neil

  47. Neil Cox said

    A GEO stationary satellite mirror could warm all of Earth, but the Sun is not a point sourse, so a long narrow beam is not possible due to beam speading except possibly from DSS = dark sky station or equivelent. Even at 100 kilometers slantrange, the illuminated area would be perhaps a square kilometer, which is ok for solar sites (or laser receiving sites) designed to receive 100 megawatts or more. Collating the sunlight into paralell beams before the mirror might allow a narrower beam? Neil

  48. Neil Cox said

    Here is a condenced version of a conversation I had almost 8 months ago on the forum at www,liftport.com
    Science & Technology Solar power satellite on January 11, 2007,-
    A possibly big customer for space elevators is SPS = solar power satellite. These can beam power to earth cities from space. Japan is planning a demonstration project. USA did a $25 million dollar study about 1985. In theory, infrared lasers can beam the energy to Earth, but present lasers are low efficiency. Laser diodes look promising. Most locations can not use more than a few gigawatts, and high voltage power lines lose more than half the energy when they are 600 kilometers long at maximum power. Room temperature super conductors would allow electricity to be sent with low loss for 1000 kilometers or more.
    Since the superconductor power lines may not happen, most people think magnetrons, which make microwaves at about 75% efficiency. I like the klysitron, about 50% effeciency as the beam can carry broadband data which can be received with a small antenna over about 1/2 of planet earth and about 1/2 of the solar system. This communications could prove more profitable than the electricity we beam down. Usually we think GEO staionary orbit = 36,000 kilometers altitude, but solar synchronous semipolar orbit, would serve perhaps a dozen rectenas around the world during their peak demand period when the wholesale price of electricity doubles. My guess is 14,000 kilometers altitude for sun sychronous semi polar orbit. This is a small disadvantage for the space elevator, but the minimum dimentions of the transmitting antenna (or sun beam mirror) and the rectenna = are reduced by about 1/2. Please add details, suggest alternatives and make corrections. Neil

    D says: You can not beam sunlight, because of its bad collimation. Such a beam alway diverges at least 1%, meaning with a flat mirror of 360 km you’d get a peak of one extra sun intensity, with a spot size of 720 km. The one sun would be in the center of the spot, it would drop off towards the edge from there. With a perfectly parabolic 360 km mirror of 36,000 km focal length, you would get a circular spot 360 km wide, with one sun intensity throughout. This would be an image of the sun, and you’d be able to make out sunspots and coronary mass ejections, most likely. People living in the area would probably not appreciate the extra sun, unless you focussed it on Northern Canada, Greenland, or Great Britain.

    J says: To go into orbit at 14,000 km with a velocity of 4.4 km/s the satellite needs dropping at 31,450.513 km and a circularizing Delta_V of -0.563 km/s applied.

    Hi D: Even if 90% of the energy misses the 20 kilometer solar receiving site, the semi-parabolic mirror may be less costly than an equivelent SPS of other types. If we assume the 100 kilometer mirror produces a 10 trillion 10^13 watt beam = 10,000 gigawatts on the average; what percentage is aimed at the 20 kilometer solar receiving site? Assume 18,000 kilometers distance from mirror to solar receiving site. There will be additional atmospheric scattering. Montana, USA on a steep South facing site might be a good location for a solar receiving site. The scattered sunlight might be appreciated at higher elevations, especially in winter. Neil

    Hi J: 0.563 kilometers per second is not a large penelty to circularize at 14,000 kilometers altitude, but the multiple rectennas will be very costly for receiving energy perhaps 10% of a typical day, unless the public can be convinced that 10 kilowatts per square meter, wont fry their hide. The international maximum for microwave oven leakage is 1/10 watt per square centimeter = one kilowatt per square meter = one gigawatt per square kilometer, and that assumes there are no hot spots in the illuminated area. We can turnoff the beam less than one second after it pans off the rectenna, but that will not satisfy some people, since the turnoff freature can be disabled or malfunction. Eventually a beam will accidentally illuminate a city, unless it is turned off at first signs of trouble. My guess is serious injuries will rare at 10kw per square meter, unless the hot spot happens to track the person and the person is unable to find shelter and/or the person was close to heat exhaustion just before the hot spot got them. Neil

    J said: In the case of a microwave system there are multiple ways of turning it off. If you make them independent you can produce a highly reliable system. Require all to report active before the beam starts.

    Possible controls.

    Gyroscopic sensor system to ensure that the beam is pointing in the correct direction.
    Radio activation message and deactivation message.
    Continuous signal (radio or laser) from Earth receiver to transmitter.
    On board physical ON/Off switch.

    If this was an Earth based system I would also suggest a physical safety key similar to an ignition key but since this is in space and there is no one to turn it, such a switch is a waste of time.

    Hi D: Most light sources have poor collimation, so we use collimators for overhead projectors and other image projectors. Perhaps CNT will make a 10 kilometer collimator practical.
    Almost anything seems better than a million times a million = 10E12 photovoltaic cells, in a series-parallel array, powering 100,000 magnetrons in series parallel. At 1/10th watt per photovoltaic cell, that’s 25 gigawatts at 30% efficiency and the overall efficiency may be less than 5% delivered to customers of the power grid of Earth. A single very fast hydrogen nucleus can short or open a photocell. Both shorts and opens cause disproportionate power loss in a series parallel array. Neil

    Hi J: I agree multiple turn off increases certainty and all those you suggested are workable. We can also turn the the solar array and/or collimator, until there is no light on the photovoltaic cells (or the light beam (or other beam) misses Earth).
    As a last resort, explosives on the power line can be detonated to open the circuit. That may be the only fast, reliable option for 10,000 amps at ten million volts, dc = 100 gigawatts which should make a spectacular arc even in the vacuum of space. Neil

  49. Hello,
    I came across you via Alan Boyle’s CosmicLog.
    Here’s a link to Gaia Two http://smythspace.blogspot.com/2007/01/smythspace.html
    I have touted her form as the ideal Space Solar Panel for years. The shape provides countless foci for absorption, as well as transmission.
    This vehicle Falls Into Space, is propelled by compressed air, is exceptionally light, yet strong…and can be returned for upgrades and repairs…and re-launched…
    The issues of escape velocity, and blazing re-entry have been solved.
    Unmanned, remote controlled versions could orbit in clusters…picture the tails together around a central point…they’d look like a big flower in space…top surfaces gathering through their concave Photovoltaic Mylar skin…bottom, convex surfaces focused to a point on Earth…projecting back via whatever means is determined feasible.
    Doable now…if there is a means of returning a positive power gain on this end….how about a Solar Powered Laser, which heats a contained body of water, producing steam…running turbines?
    I realize this is pretty vague…ask Alan Boyle for more info…he’s been aware of my intent for nearly a decade.
    alan.boyle@msnbc.com
    Suffice it to say that a brainstorming session with knowledgeable individuals could make this reality…soon!
    Steve Smyth
    SmythSpace
    http://www.smythspace.tv

  50. Charlie Siegrist said

    I have read with interest the talk about utilizing a space elevator for stringing conductors that would transmit power from a space solar collector to Earth. From what I know of the hypothesis of a space elevator, it is based on nanotechnology, which combines light weight with high strength, and is at present severely limited by the length of nanotubes that can be formed.

    So, what is going to happen when heavy copper conductors are dropped alongside the space elevator? Besides the thorny problems of velocity and torque that will be imposed by hanging this huge weight from a LEO anchor, the long conductor will be a huge attractor for lighting and other atmospheric electrical phenomena.

    Where is the space elevator going to be located? If in the ocean as some have suggested, then where are the substations and transmission lines going to be placed at the reception end?

    Unless nanotechnology can also be adapted to the conduction of huge amounts of electrical energy, the approach of using solid conductors to transmit energy from space to Earth is not an implementable solution. I don’t see an alternative to microwave power transmission.

  51. Jannet de Castro said

    Why would scientist want to use solar power to propel a spaceship?

  52. Neil Cox said

    Hi Jannet: Traditional space craft carry both oxident and fuel, which totals more than the mass of the payload, sometimes a million times. Solar energy can be received as needed, so only reaction mass needs to be ejected, in theory much improving speed, range and performance. Neil

  53. Neil Cox said

    I typed most of this somewhere on this site before, but I think I am better organized now:

    Sun light reflectors in LEO can beam sun light though gaps in the clouds, but the illuminated spot is huge, and not much brighter than twilight if the reflector is one square kilometer. This is because the sun is not a point source, and collating the light would be difficult.
    The reflector needs to be closer. This makes the beam narrower = spread less. One square kilometer reflectors supported by very large balloons at an altitude of about 20 kilometers, could illuminate almost one square kilometer (through a gap in the clouds) almost as bright as full sunlight. Ordinary solar sites could harvest this energy, Disadvantages are: The reflector is in the dark about one hour after sunset at the receiving site. About one billion balloon reflectors are needed to power all the nations of the Northern Hemisphere. The balloons and mirrors would need to be recovered inside the Arctic Circle a few months after they were launched near the Equator. We would have to inflate the balloons with hydrogen, as we can’t get enough helium at reasonable cost to inflate a billion very large balloons.
    Alternately the balloons could beam down micro waves and/or collimated laser light to tiny rectennas and/or solar sites. This would be very good with the idea of supplying energy to small villages in third world countries which presently have little or no electricity. It also helps with distributed power which is almost terrorist proof.
    We could fly a few such balloons to test SSP technology as big balloons are much cheaper than even LEO.
    We do have an SSP group at http://www.pickensplan.com Enter SSP in the search at the upper right of most pickens pages. You get about ten hits. The 4th 5th and 6th have the words space solar power in the last line click on these words and you get the SSP group which has some good ideas in the comment wall. Put it in favorites or you may not find it again. Neil

  54. Neil Cox said

    I reviewed the info (click upper right)about Japan’s future Space Solar Satellite. The arithmetic agrees 1.8 miles is 3 kilometers, so radius is 1.5 kilometers and area is 7.07 square kilometers to put one gigawatt on the grid. Perhaps 1.41 gigawatts falling on the rectenna. That is 200 megawatts per square kilometer = 200 watts per square meter = 0.02 watts per square centimeter which is 1/5 th the allowable leakage from a microwave oven. That should be reasonably safe, even if the beam falls on a city instead of the rectenna for many hours. We are hoping for better than 70% efficiency for the rectenna, but I think even 70% is optimistic as the grid voltage is 100,000 volts or more, 60 hertz 3 phase ac for one gigawatt input. Perhaps 2 million volts dc. at 400 amps = 0.8 gigawatts to be sent to a city hundreds of miles away. I don’t know if it is practical to connect perhaps 10 million rectenna elements in series to get two million volts. What is the highest voltage from a rectenna to date? Neil

  55. Neil Cox said

    So how did we make the 1410 megawatt beam
    3.6 by 3.4 kilometers rectangle = 12 square kilometers times 1353 megawatts per square kilometer = 17,000 megawatts times 20% = 3300 megawatts dc output. Perhaps one million volts at 3300 amps, delivered to 2000 (about 50% efficiency) klystrons (connected in series-parallel) at the end of a ten kilometer umbilical cord. The wave guides from each klystron forms a phased array, which produces the 5 kilometer illuminated spot on the rectenna on Earth’s surface. Some energy is scattered from the beam, so perhaps 1410 megawatts falls on the rectenna which has an area of almost 20 square kilometers. That is 71 megawatts per square kilometer = 71 watts per square meter = 0.0071 watts per square centimeter.
    The allowable leakage from microwave ovens is about 14 times greater, so the hazard is negligible, even if the beam falls on a city for a week, instead of the rectenna. Reasonable precautions can shut down the beam in less than one second if it is not falling on the rectenna, so we can possibly make the rectenna considerably smaller for a 1500 megawatt beam. A trillion dollars is a reasonable cost estimate with present technology, but secret and near future technology may make the cost more reasonable.
    20% efficiency is optimistic for thin film photovoltaic which will likely be used as they are much lighter weight than the usual panels NASA uses. The umbilical cord allows the beam to be sent toward the sun, when the Earth transits the sun as viewed from the satellite. It also allows positioning so that the beam does not hit the solar array and the klystron array does not shade the solar array. It will be necessary to untangle the umbilical cord several times per decade. Klystrons are preferred as they cause less interference than magnetrons, plus wide band modulation is practical. The scattered 200 (some is absorbed) megawatts allows a modest antenna to receive the broadband data over about 1/2 of Earth’s surface and about 1/2 of the solar system. The broad band data may be more valuable than the 1100 megawatts put on the grid by the rectenna. By aiming the 1500 megawatt beam, so it misses Earth, we have a RADAR system that has a range of billions of miles. Billions of unique pulses can be sent out to allow for range information of echos from the Oort cloud, if any return from that far away. Neil

  56. Neil Cox said

    The following is a shortened version of a thread at Technology at http://www.space.com J said: I was looking at several different ways to transmit energy using either one of these media; laser/ Maser/microwave/radio waves etc. the high efficient solid state Yb:YAG or Nd:YAG laser can be over 50 percent efficient and one place claimed to be making a 80 percent efficiency solid state laser for the government. The efficiency of the arrays is typically greater than 50% at their rated output power (electrical input power to optical output power after the collimating microlenses). http://www.laserfocusworld.com/display_article/31593/12/none/none/Feat/Diode-pumped-Yb:YAG-catches-up-with-Nd:YAG The US department of defense is working on a mobile solid state laser that would be 100 kilowatts, will they share that info. No I don’t think so. There is some 10 kilowatt solid state laser being used in industry. So to have a lot of lasing energy you need lots of lasers. A lot of the times the claims for laboratory type lasers are not close to real world, but if you are using the energy from wasted gas, like vented natural gas then 20 percent of something at the receiving end is better than 100 percent of nothing…. There are some drawbacks which may prevent some high efficient lasers such as power output in kilowatts, doping, cooling the laser, what wavelength you use, hours of operation, cost, it needs to go through the atmosphere efficiently etc, etc. If we use a solid state laser what type of power station would you use to produce the electricity for a solid state laser and at what efficiency???There are a lot of obstacles we need to overcome but maybe they are manageable…
    Neil said: I have heard the 50% claim for solid state lasers before, but several disadvantages such as a thousand times a million of them needed to produce a thousand times a million watts = one thousand megawatts = one million kilowatts = one gigawatt = enough power for 1/2 million homes. Another problem is getting all those laser diodes to phase lock with each other = a coherent beam. A very coherent beam is needed for a phased array which has several advantages over a multi mile parabolic dish. Does anyone know if a big dish also requires very coherent for a very narrow beam? A separate issue is the laser light needs to be highly collimated. I don’t think an ordinary lens can collumate? The common collimators used for slide projectors waste more than half the light and better collumation is needed than typical projectors. Do we know how to collimate without large losses? We have not built a dish or phased array bigger than one kilometer, so there may be more surprises when we do. If the phased array is one kilometer by one kilometer, the average energy density is one thousand watts per square meter = 1/10th watt per square cm = the allowable leakage for microwave ovens = reasonably safe and reasonably doable. The laser diodes and their optics, if any, are mounted 31 (if my arithmetic is correct) centimeters between centers which likely is enough room since the laser diodes are tiny. Apparently each laser diode needs an elaborate (or over priced?) current source, which could add considerable weight and cost.

    Since each laser needs about 1/2 volt, operating a million or more in series is desirable to keep total current reasonable. That should make for the same current in each laser, so perhaps only the 1/2 million volts or more needs to be regulated precisely. Perhaps a negative temperature coefficient diode could snuggle up to each laser diode, so it would lower the laser diode voltage if hotter than optimum. Down side is severe arcing if one laser and it’s thermal diode has an open circuit. A shorted laser diode causes negligible mischief out of a million plus in series. All this stuff I typed is without the benefit of advanced math so, it may be erroneous.

    On the positive side, a branch of the Department of Defence is conducting the chief USA SSP = space solar power planning, so they may be able to access highly classified DOD data. They have an excellent public forum at http://spacesolarpower.wordsmith.com
    E said: I was interested in this new state of matter these scientist have said they found. Here’s a quote from the site you listed.

    The Pitts researchers have been working on a project to create materials which mix the characteristics of superconductors and lasers and have successfully captured the polaritons in the form of a superfluid, using optical nanostructures, thus resulting a form of matter called a polariton superfluid, in which the wave behavior produces a pure light beam similar to that from a laser but is much more energy efficient. E

  57. Jim S said

    I have seen some of the environmental concerns being mentioned, but most concerns are being gleefully pushed aside as optimistic potential is slavishly spread over all. CRap!
    The major environmental scientists have much to say against this possible use of solar from space and the proponents are not listening and that will hurt solar power and space exploration in the near run greatly. How can proponents push so blindly when warnings are all about, this is a terrible disaster waiting to happen to science if it is pushed forward.
    The political arguments against this type of project are immense, and they come from the Far Right, as well as the Far Left. Of course if the Far Right had their way the sun would likely be put out so they could sell more coal and oil to heat homes, this would shortly end in O2 depletion, but think of the profits in the mean time, lol.The far left have concerns that while they may seem exagerated, may actually be understatements of what could be fact; due to a missunderstanding of domino principles in environmental equations, equations which really need better understanding and research by the way.It may be possible for humanity to gather enough knowledge in the future to actually KNOW how to control global weather and environment, but we need to survive long enough to do so.
    The simplistic concern is of course about how much external “heat” will be brought into the Earth’s environment from an external source; (Space). Once it is on our side of the greenhouse gases CO2, Methane, etc, then it will need to fight it’s way back out to be radiated into space again. It doesn’t matter what form it is initially brought in as, thermodynamics are quite simple , we may change it’s form but whether used for work or heating etc, it still becomes part of the global warmth factor. It is said that the reduction in CO2 emissions will help make the greenhouse barrior less of a barrior. However, it is now estimated that due to the current projections of global warmth CO2 will be released from the natural environmental sources in greator amounts than what we could change if we stopped all use of CO 2 emissions. Natural sources such as Tundra warming and even warming oceans and increasing acid content that might lead to great releases of methane. The last time this happened, it is said that over half of the species on Earth became extinct!

    In other words we will do vastly more harm to the environment than we have ever done before. We need space exploration and space based technology if we are to control the global environmental issues. We need solar panels on Earth to start using the available warmth that is already here, instead of beaming in more heat. We can’t shade the Earth because we need light for the organisms that absorb CO2 in our oceans to coninue to do so, as well as producing O2.We actually need a period of cooling very soon to prevent the release most importantly of Methane, that would be a far worse Greenhouse barrior gas than CO2, while amounts aren’t that great, we could see a huge release in the next 5-20 years and then we could be in a no win situation. Note that this could happen even before solar power to Earth plans are enacted. At that point we would be in dire staits, and beaming in more heat would be our final coffin nail.

    • Neil Cox said

      Hi Jim: I’m not aware of more than a tiny percent of environmental scientists being concerned about heating Earth with energy from SSP = space solar power. The area of a sphere is 12.56 times the radius squared. The radius of Earth is about 6000 kilometers, so area of Earth’s surface is 12.56 times 36 million = 420 million square kilometers. 420 square kilometers of PV in space would thus add one part per million to the heating of Earth, at 100% efficiency. 20% efficiency is optimistic for SSP, so we need 2100 square kilometers of PV panels in space to heat Earth 1 part per million. We might orbit that much PV over the next few centuries, but far less will be orbited in this century, so heating Earth with SSP will be negligible long term. If we are deep in an ice age in a few centuries even a tiny amount of extra heat will be appreciated.
      Competition with solar power on Earth’s surface (by SSP) will also be minor for the rest of this century, so any supposed hurting of solar power will be bad analysis. An increasing number of scientists are concluding climate change is seriously exaggerated. Neil

  58. Neil Cox said

    ~The following is my comment on the June 26, 2009 Wall Street Journal article.~ The 2500 megawatts mentioned in the article is enough for one very large city. The receiving site occupies several square miles to be completely safe. Several good things happen if we do this, large scale: Reduced water, coal, nuclear and oil use. Reduced polution and carbon dioxide emissions even compared to the best renewable energy methods, on Earth’s surface. Occupies less land area even at extreme amounts of energy.
    At 2500 megawatts, delivered to one square mile, you would want to remove your winter coat after a few minutes exposure, so you are in trouble if it is a hot summer day. From 22,000 miles = GEO altitude, several square miles is the minimum size spot the beam illuminates, unless we go to a shorter wave length such as millimeter waves. With lasers, minimum spot size is perhaps 100 feet and it is deadly in seconds, even on very cold days. Aluminum foil or other metal does give some protection, but it needs to be grounded. Present lasers have low efficiency, and high cost, but lasers may be practical by 2016, as the technology is still advancing rapidly. Thick clouds are a problem for laser wavelengths.
    The solar panels can be deployed in LEO = low Earth orbit and can likely power the assembly to GEO altitude = 22,000 miles, but we have not done this even small scale, so some surprises are likely. Neil

  59. We are receiving only 1/2.3 billion of sun’s output and aren’t making use of it efficiently. With a more egalitarian approach, this technology can solve the energy problem for the whole world. But it can also turn into the oil of the new world… and a nonrenewable one. Politics is very much intristic to it.

    Also a major draw back is high development costs, although much smaller than American military presence in the Gulf, or the costs of environmental impacts of nonrenewable sources.

    Space elevators can be a good idea, though

  60. Maury Markowitz said

    The math is very simple:

    1) Calculate the amount of power you expect to generate by your panels over their lifetime, if they are placed in the Nevada desert.

    2) Calculate the amount of energy you would generate by the same panel placed in GEO.

    3) Calculate the launch costs of placing those panels in orbit.

    (2) will be 3 to 4 times (1). (3) will be about 10,000 times (1). So you’re always better off leaving the panels on the ground. That’s all there is to it.

    There are other considerations. GEO orbit is clogged with dead sats and there’s absolutely no way a SPS will last more than a couple of months before being hit. There’s also the question of launching hundreds of rockets and the impact they have on the environment. And then there’s the fact that 100% of our attempts to build objects on this scale have failed.

    It’s a pipe dream, stop smoking it.

    • Neil Cox said

      Hi Murry: It is hard to argue with your math, but launch costs, and launch polution may be much less if the space elevator or other advances occur. Yes there are other considerations: GEO harvests more than 4 times the energy of the Nevada desert in December. The transmission losses and rectenna losses, however make 4 times about right.
      There are costs and energy losses getting the Electricity from Nevada to where the customers are. Considerable extra polution is released building 4 times as many PV panels or concentrating solar. Energy storage and/or coal fired plants produce lots of polution to supply electricity when the sun is below the horizon in Nevada. Most of the dead GEO satellites are in a parking orbit about 1000 miles higher than GEO altitude. Those dead satellites at GEO altitude are orbiting very close to the same speed as the SSP = space solar power satellite, so collisions are gentle and rare.
      Until we learn to build very large scale, we can build lots of small SSP, perhaps in sun synchronous orbit instead of GEO orbit = lots less space junk. We do need to design so the SSP continues to operate satisfactorily with some holes busted in the PV array and the transmitting array. Neil

  61. Jim S said

    Hello Neil,
    I rather agree with some potentials of “other advances” in space propulsion, but have very serious grave doubts about “A Space Elevator”. If it wasn’t for Arthur C Clarke’s popularizing of the Elevator concept especially in the 90’s as he grew older; “3001”, I doubt many would be even be giving it a second glance. Nano materials could never withstand the inertial shear differential of it’s own mass as it proceeds through various suborbital-orbital regions. See “orbital shear” which is almost entirely neglected by todays elevator proponents. None the less, if our species does not self destruct, space based solar power in large quanity may become feasible sometime in the future, guestimates vary, but use of the power in space will most likely be more advantageous than beaming it to Earth. None the less there are many uses of such beaming technology, and so do agree that it should be researched.
    Jim

  62. Chris said

    Sounds like science fiction to some, however the maths seems to support the concept, now to find a backer and build the first system!

  63. The political arguments against this type of project are immense, and they come from the Far Right, as well as the Far Left.
    The simplistic concern is of course about how much external “heat” will be brought into the Earth’s environment from an external source; (Space). Once it is on our side of the greenhouse gases CO2, Methane, etc, then it will need to fight it’s way back out to be radiated into space again. It doesn’t matter what form it is initially brought in as, thermodynamics are quite simple , we may change it’s form but whether used for work or heating etc, it still becomes part of the global warmth factor. It is said that the reduction in CO2 emissions will help make the greenhouse barrior less of a barrior. However, it is now estimated that due to the current projections of global warmth CO2 will be released from the natural environmental sources in greator amounts than what we could change if we stopped all use of CO 2 emissions. Natural sources such as Tundra warming and even warming oceans and increasing acid content that might lead to great releases of methane. The last time this happened, it is said that over half of the species on Earth became extinct!www.gtacarservices.com

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

 
Follow

Get every new post delivered to your Inbox.

%d bloggers like this: