Space-Based Solar Power

a public discussion sponsored by the Space Frontier Foundation

Where’s the Final Report?

Posted by Coyote on September 15, 2007

Space-Based Solar Power Advocates and Critics,

September 15th is here…so where’s the final report from the National Security Space Office that was promised???

There won’t be any. Well, not a final report, and not by close of business today.

On the 6th of September, following the first day of the Space-Based Solar Power Conference held in Breckenridge, Colorado, Mr Joe Rouge, the Deputy Director of the National Security Space Office, issued new orders to the director of the study (me). It was jointly determined between several officials and conferees that space-based solar power merits even closer look in several areas. No findings are yet final. We still have more questions than answers. Therefore the National Security Space Office will issue an interim report in October, and will continue thereafter!

Tentatively, the National Security Space Office may release its interim report at a National Space Society event held at the National Press Club on 10 October, 2007. This has not yet been finalized, but it may be the right type of event to get the word out about the awesome potential of space-based solar power and the challenges that must be overcome to help the commercial sector proceed in this endeavor with a successful business case.

The emphasis throughout this study is that the DoD wants to be a customer of clean energy from space, not a producer.

To foreshadow the interim report, it will likely address the following in some form or fashion:

  • The study design: The first-ever DoD led study using the Internet in a wide open public forum to develop a future concept, including:
    • Vision
    • Mission
    • Assumptions
    • Methodology
    • Limitations
  • Goals:
    • 10% U.S. electric baseload by 2050
    • Crawl, walk, run approach
  • Open Trade Spaces (Requiring greater analysis and testing):
    • Lift: Expendables? Reusable rockets? Spaceplanes? A mix? How many? Launch sites?
    • Energy generation on orbit: Photovoltaics (panels or concentrators?)? Solar dynamic (what type?)?
    • Power transmission to Earth: Microwave? Laser? What frequencies for either?
    • Scalability of small space solar power satellites to large (Kilowatt range to Megawatt range to Gigawatt range): Which technologies are best in each scale? What testing is unique to each scale? What learning is needed?
    • Earth reception: size and types of rectennas? Intellectual properties?
    • Legal issues: Liability? Indemnity? Licensing? Frequency managment?
    • Orbitology: Which orbits are best suited for each scale? What geostationary slots will be required and when? What orbits will be used for assembly and transfer?
    • On orbit assembly: Robotic? Man-robot mix? What orbits will be used for assembly? Assemble low and transfer high? Finally assembly at geo?
    • Orbital transfer: Self-propelled or independent space tugs?
    • Operations: By whom? From where? Telemetry and station keeping? Ground network?
    • Liquification: How? Where? What types of liquids? Distribution?
    • Business case: How does the commercial sector get involved? What will stimulate investment along the critical path?
    • etc
  • Findings and Recommendations:
    • Pending (okay, the caballeros know what the findings and recommendations are…but we have to keep you in suspense until we release the interim report, right? Here’s a hint…if you read every word on this website you will know most of what will appear in the report!)

22 Responses to “Where’s the Final Report?”

  1. Des Emery said

    Hi, Coyote – I’ve been off a while and I’ll have to study to catch up on what’s going on. But a quick perusal leaves me with this — Global Warming is more imminent than was supposed up to now, and Space Solar Power could provide the cheap electricity needed to slow it down, stop it, or possibly reverse the damage it is causing. As you have noted, food wars are quite possible or even inevitable in our future due to the effects of Global Warming. A plausible prevention could be the use of solar power to split carbon dioxide into its components, carbon in solid form to bury again, and oxygen in gaseous form to release back into the atmosphere. This endeavour would not necessarily be profitable, but could operate as an international effort to benefit all in the reduction of greenhouse gases.

  2. Edawg said

    independent space tugs are the way to go. here is an existing design from 04

    you can also use the triton booster on any ‘new’ CEV designs

  3. Michael said

    Hey Coyote (and all),

    Why are we so fixated on DoD NOT being the developer and producer of clean energy from space? DoD already built, owns and operates one global public utility in space – Precision Timing and Navigation via GPS constellation.

    Is there a model here we can look at? Last I heard no one is proposing transitioning GPS-III to a commercial entity.

  4. Eric said

    Let’s see if I have this right, the NSSO seriously believes they can convince the world the high power directed energy device they are developing to “beam power to earth” won’t be seen by China, Russia, et. al. as a space based weapon. You guys need to go back to Space Law 101. Until the orbiting of weapons of mass destruction stops being banned by international law this proposal is DOA without regard for any “it’s green power” arguments. Stop wasting your money on it.

  5. the NSSO seriously believes they can convince the world the high power directed energy device they are developing to “beam power to earth” won’t be seen by China, Russia, et. al. as a space based weapon.

    Couple of basic points to keep in mind when considering a GEO-SBSP platform as a potential weapon in the eyes of rival superpowers.

    1) It’s in GEO – remains fixed in relation to a spot on the ground
    2) If we are providing power to our own population – said GEO spot will be in this hemisphere
    3) You can’t see Moscow or Beijing from a GEO sat serving Arizona

    Now, granted, the Canadians might be a bit worried (and, frankly, they’ve been getting a bit uppity recently with this whole northwest passage thing, so they should be worried) about us flying a SBSP over this hemisphere – but seriously, people: Look at a globe once in awhile.

  6. Alienthe said

    Here goes my attempt at summarising the use of L2 using the report headlines.

    My basic premise is an annular mirror located at Sol-Earth Lagrange point L2 (that is 1,500,000 km from Earth), inner radius about 6000 km (circumference 40000 km) and width starting at 1 m and scaling upwards. Weight of mirrors would be of the order of 100 tons.

    * Goals:
    o 10% U.S. electric baseload by 2050
    I hope that this is a wider scope than generating 10 percent of the load and also includes savings that amount to this baseload. In proposing beaming energy as plain light it can save a lot of electricity in terms of lighting and provide added photosynthesis that will absorb excessive CO2.

    o Crawl, walk, run approach
    Hear, hear. Soviet (and later Russia) often went with the simplest technology that did the trick and very little more. That made MIR last quite a few more years than Skylab. The Space Shuttle is an example of troubles that arise when you reply on a huge number of complicated components; even if all are rather reliable the probability of absolutely all working flawlessly decreases with increasing count, increasing complexity and increasing interconnectedness. The West has a few things to learn here in terms of design philosophy.

    Solar dynamics rely on lots of mechanical components, possibly operating at high speed. Add in the limited experience in such use I would definately say the risk is way, way too high at this early stage. Even photovoltaics require high tech and I am suspicious of the little concerns shown for cooling the microwave subsystems. You could combine the optical concentrators from solar dynamics to photovoltaics; using “30 solars” concentration is used in evaluations in labs and this would save weight, materials and complexity.

    Far simpler then is to use large concentrators and just beam the light to Earth. More on this below.

    * Open Trade Spaces (Requiring greater analysis and testing):
    o Lift: Expendables? Reusable rockets? Spaceplanes? A mix? How many? Launch sites?
    I just checked and found to my pleasant surprise that Saturn 5 could lift 118 tons to LEO and 47 tons to lunar orbit. With an unmannes system we are already in the right ballpark and that is with 1960’s level technology.

    o Energy generation on orbit: Photovoltaics (panels or concentrators?)? Solar dynamic (what type?)?
    Concentrators of light, split light by wavelengths, transmit to Earth by optical cannons using 10 m apertures. Quick back-of.the-envelope calculations regarding diffractions (dropping Airy disk corrections, just order of magnitude)

    Spread = distance * wavelength / aperture = 1E9 m * 1E-6 m / 10 m = 100 m

    Clearly the small wavelength compensates well for the larger distances involved when compared to GEO.

    o Power transmission to Earth: Microwave? Laser? What frequencies for either?
    I propose visible light. First of all the smaller wavelengths makes it more practical. Also you have no problems knowing just where the beam is, people will worry about things they cannot see, smell or hear and we have alredy seen one person being more than a little sceptic in these discussions.

    Using ISM bans in the GHz range will make lots of people unhappy when their WLAN, Bluetooth, Zigbee and other things stop working.

    Infrared is also hazardous as it does not stimulate your blink reflex. In fact IR is probably the least useful band as it is too low to be of much use in photovoltaic conversion on the ground.

    However 5 KW/m2 energy density as visible light will be glaringly obvious, uncomfortable to stand in but not hazardous. Use shades, the Space Solar Power future is so bright you gotta wear shades.

    Light has many uses such as: highly efficient photovoltaics, eliminate street lights, eliminate vehicle headlight use, reduce indoor electrical light use, increase crop yield and CO2 uptake by increasing photosynthetic activity (ref areas north of the northern polar circle to see how nature has coped with 24 hours sunlight in summers), and probably much more. Probably th eonly two groups that would complain are those who need dark nights to see the stars: astronomers and poets.

    o Scalability of small space solar power satellites to large (Kilowatt range to Megawatt range to Gigawatt range): Which technologies are best in each scale? What testing is unique to each scale? What learning is needed?
    Again light works well. An annular mirror can scale by sliding new mirror panels from the hub out along the wire spokes to the circumference. Slowly rotating it would just need inertia to slide under its own power.

    Power is 1KW/m2, and a start at 4E10W wouldn’t be too bad.

    o Earth reception: size and types of rectennas? Intellectual properties?
    No rectenna needed, just high bandgap photovoltaics. A van with 10m x 3m top would have 75KW power available, at 750W pr. hp that is 10 hp without any chemical fuel needed. As for IPR I haven’t looked but I would recommend getting someone to check out solar panel steering for satellites.

    o Legal issues: Liability? Indemnity? Licensing? Frequency managment?
    Many unknown. However frequency management of optical wavelengths has never been regulated before. ISM bands do have certain restrictions in some countries in addition to being heavily used already to the point of overcrowding.

    o Orbitology: Which orbits are best suited for each scale? What geostationary slots will be required and when? What orbits will be used for assembly and transfer?
    This is a harder issue at L2 than it may appear at first. L2 is unstable and requires station keeping (L4 and L5 are stable). Second hand info is that sailing the solar pressure is possible but complicated. The Moon obscuring sections every 28 days is a complicating factor that needs to be compensated for(the Moon is a high mainenance mistress). On the plus side is the fact that you can use the mirrors as sails, saving use of propellants, movements are small and Earth-Lunar lagrange points are much closer to Earth than this working area.

    L2 has not had any commercial value up to now (while GEO is regulated and high value properties that are squabbled over) but that might change. Bonus points: using solar pressure you can operate on the inside of the actual L2; and you can use this system as a wakeboard for ultrahigh vacuum production (tested on the Shuttle).

    o On orbit assembly: Robotic? Man-robot mix? What orbits will be used for assembly? Assemble low and transfer high? Finally assembly at geo?
    Try automated deployment from a modified Saturn 5. Start with a hub, slowly rotate it and spool out the wire works before spooling out the mirrors on these wires. Transoceanic wires are already on this scale of lengths and nanotube grade strengths are not needed. Again we have the right tech level yesterday already. Next just add more mirrors as needed.

    o Orbital transfer: Self-propelled or independent space tugs?
    Self propelled and unmanned.

    o Operations: By whom? From where? Telemetry and station keeping? Ground network?
    Tricky, tricky. Ground network would be moving but always the nigt side, that is the advantage.

    o Liquification: How? Where? What types of liquids? Distribution?
    USe photovoltaics where possible at 5+KW/m2. You can get photogenerated hydrogen but that requires water which is scarce in many conflict areas.

    o Business case: How does the commercial sector get involved? What will stimulate investment along the critical path?
    Japan is already interested in buying, energy costs there is high. Night time is like a blackout due to costs. You can sell on a city scale block of allocated lighting subscription.

    o etc
    * Findings and Recommendations:
    o Pending (okay, the caballeros know what the findings and recommendations are…but we have to keep you in suspense until we release the interim report, right? Here’s a hint…if you read every word on this website you will know most of what will appear in the report!)
    I am looking forward to that.

  7. Neil Cox said

    I don’t know why we would bury the carbon we separate from carbon dioxide while we are digging up carbon.
    I have not seen a discussion on the practicallity of space tugs. I suspect more than 1/2 of their fuel would typically be used getting to their next assignment in a reasonable length of time. Are you thinking a crew on each space tug? Neil

  8. Neil Cox said

    I agree with Shubber: The SBSP = SPS we build before 2040 at GEO altitude cannot be used to cook humans, even directly under the satellite. I think we will have difficulty producing one kilowatt per square meter anywhere on a rectenna (or laser receiver) on Earth due to the 36,000 kilometers. The Mexicans and Vensualians will have a slight reason to worry, Canada and Morocco are too close to the horzon and most of the rest of Earth is below the horizon, as viewed from an SPS serving a USA city.
    Demonstration SBSP in low Earth orbit will likely be a megawatt or less, so they will also be near worthless as a weapon.
    If we build a gigawatt SBSP at an altitude of about 15,000 kilometers, in semipolar solar synchronous orbit; then most everyone can worry at peak electric demand time early some evenings. A solar synchronous SBSP would time share its beam to about a dozen Earth cities around the Earth each 24 hour orbit. Neil

  9. Edawg said
    The Jupiter launcher will solve plently of National Necurity headaches and pride.Commercial sector will fill in the gaps 😉

    For the modern Russia, as for the other world nations, cosmonautics now is not only the subject of national pride. Exploration and application of Earth-orbital space become serious resource of national development and real advancement of peoples living standartds.”
    President of Russian Federation Vladimir Putin,
    Moscow, Kremlin, 12 January 2007

  10. Edawg said

    Sputnik turned 50 two days ago,this article is a very good read…Jupiter will finally bring credibility back to our Nations space faring ability.Plus we wont have to worry about the Asteroid Apophis and that is MY generations problem !

  11. Neil Cox said

    Here are somemore miscelanious thougts. Balloons, kites and FEGs = flying electric generators typically have a tether running to the ground, requiring a no fly zone. Bad weather can be a problem for the tether even if the FEG etc mostly fly above the weather. Generally they can be landed if the bad weather is predicted, but this does add to operating cost. FEGs optimised to produce power at 20,000 meters will fuction poorly at 50 meters and thus may be damaged landing in bad weather. Repairs are very difficult without landing. Replacing elements of a SBSP in orbit will be difficult and costly. Add the fact that you still have between 8 and 14 hours nights when the energy decreases to negligible except kites and FEGs produce 24/7. Nights are almost this long in LEO = low Earth orbit.
    We do exploit ground level solar radiation much too little. No matter how big you’ll make that balloon it will be dwarfed by a square mile of photo-cells.
    It is getting funding which is difficult for all these projects, including SBSP.
    If a plane or satellite flies through the beam of microwaves or a laser beam, damage is unlikely, but some low cost improvements and pilot training can reduce the hazzard to near zero. We can know where the beams are to the nearest meter, if we don’t get careless. Neil

  12. Brian Wang said

    Congrats on the imminent announcement (Oct 10, 2007) of the new alliance to “ensure that the benefits of renewable clean energy from space solar power are understood and supported by business, governments and the general public.

    The inaugural event of the new alliance, to be held at the National Press Club in Washington D.C. at 9:00 am, will highlight a study underway by the National Security Space Office (NSSO) on the viability of space-based solar power [that is this website, pat ourselves on the back, hooray for us], presented by Lt. Col. Paul Damphousse, National Security Space Office. John Mankins, President, SUNSAT Energy Council, a leading expert on space solar power, will also speak.

    According to the organizers, media and Congressional staff who wish to attend can email Katherine Brick at

  13. Gary Oleson said

    I read a review of a book, Break Through: From the Death of Environmentalism to the Politics of Possibility, that aims to create a more positive approach to environmental problems, emphasizing innovation and investment. It might help create a supportive narrative for space solar power.

  14. Looking forward to the Interim Report, and thanks to the team that has made this a public process via this blog.

    In addition to the business case, I argue for a Societal Case discussion. This technological challenge is nested in social and political contexts, from the use of solar system resources, to the global, national,region, city, town, family, and down to the individual consumer. Understanding the impact of this, early, is as important as the technological challenge, for technology choice and options are never ever divorced from the societal contexts in which the decisions are made.
    Kat Connell

  15. Alienthe said

    I have been thinking a bit about orbits and would like to summarise for further discussions:

    A number of orbits are possible though all have quite different operating consequences on use, law and design. For reasons I have not found it appears GEO is preferred in this project. That might not be an entirely straight forward choice. By category:

    Geostationary Orbit – GEO
    On the plus side there is no doubt that this is well established technology. It is however a long climb up the gravitational well and more importantly it is a limited resource. At an altitude of ca. 35800 km, ground being about 6400 km from centre of Earth we get a circumference of ca. 26400 km. Positions in GEO are allocated in degrees, one degree spans 735 km. Some positions are more popular than others, particularly where a meridian spans numerous countries. Also these are used for several kinds of satellites (Broadcasting, point-to-point, earth resource monitoring, sciences, weather, various military puposes and more) so you might have to share a position with, say, 10 other users. Add some margins for station keeping (bumper-to-bumper is not the way to drive in the skies) and suddenly a satellite sized in the 10s of km in span is not that popular with other countries.

    A quick Googling shows there are discussions in the UN about rights of access:

    As for claims –

    Geostationary orbit: The Sub-Committee noted a decision of the World Administrative Radio Conference declaring itself not competent to deal with specific principles concerning demands made by equatorial countries to have sovereignty/jurisdiction over segments of the geostationary orbit superadjacent to their territories, and to preserve those segments for the “opportune and appropriate utilization of the orbit by all States, particularly the developing countries’.

    As value increases one should expect more of this. What they cannot reach or use themselvs they might still feel like renting out to others. Debate has been gong on for decades, one should not expect resolution anytime soon.

    A SBSP satellite in GEO would need to be articulated: one part always facing the sun (one rotation per year), the other facing the receiver on Earth (one rotation per day). Making this Earth facing platform a slot in platform for other users would limit the congestion, provide plenty of power, save in station keeping and provide good will.

    A position in GEO would mean a grazing angle at higher latitudes and thus larger rectennas for microwave power downlink.

    Highly Elliptical Orbits – Molniya and Tundra

    These feature apogee dwell so they appear to rest for a long period in one area in the sky, typically at higher latitudes which would mean a more normal angle of incidense and thus smaller rectenna farm. These are little used, are less limited than GEO and therefore far less controversial.

    On the negative side is the fact these pass through the van Allen belts and would need to be radiation protected. A cohosting facility means someone could set up an alternative to GPS (using high precision clocks for say DAB broadcast in the L-band, not sure if the US would like that). Then again it could also be used to amend GPS coverage significantly since DOP around 60 degrees latitude is worse than many other latitudes.

    Articulation would be very different from GEO, from what I can see it would be less motion thus less wear.

    Such orbits would be useful for mirrors relaying power beams to latitudes far outside the equator and for added flexibility when extra power is needed. Such relay systems were studies during the 80’s as part of the SDI, so I expect the DOD to have plenty of information on how best to accomplish this, not sure if it is all openly available though.

    Halo Orbits – SE L2
    Well, let’s face it: this is my hobby horse… Anyway, orbit is basically vacant, no controversies yet. Articulation is simpler, basically the incoming sunlight is mostly parallel with the power downlink, be it in the form of microwaves or as lighht. This means minimal mechanics and minimal wear.

    More importantly by having a passive outer rim (mirrors) and any active parts in the shadow of the Earth you are protected from solar storms by up to 12000 km of rocks. A km scale solar panel would have to be turned edge on to protect from such storms and the angular momentum is simply enormous. That problem simply is not there with an annular mirror as I have proposed.

  16. Neil Cox said

    L2 may be better than L1. L2 does not cool Earth which will be important if we enter a new ice age soon. Both are about 1,500,000 kilometers from Earth, so it is a long trip to install a SSP either place. Since we need to minimize the mass (or wait until the materials can be obtained from the Moon or asteroids) the SSP will behave somewhat like a solar sail. That means the actual location may be as far away as 2 million kilometers for L1 or as close as one million kilometers for L2. At closer than L2, the solar sail feature will normally hold the SSP just outside the shadow of Earth, so the SSP can be moved quickly into the shadow of Earth, if we need to shut off the beam, or dodge a CME = coronal mass ejection.
    A L1 SSP will beam energy to the dayside of Earth, while a L2 SSP will beam energy to the night side or twilight side of Earth where surface solar energy is not available. L2 does not compete with surface solar, which is a big plus in my opinion.
    Disadvantages are the solar constant is about 1000 instead of 1275 just outside Earth’s shadow. 2 Earth locations need about 3/4 as much power after about 9pm as during the peak demand period an hour or two earlier. Both these problems are mostly solved, if the solar sail feature has enough thrust to pull the SSP 10,000 kilometers from the center of Earth’s shadow. 3 Adjusting the attitude of the solar panels to behave as a solar sail adds complexity, especially if solar concentrators are used, but I think this is doable.
    Another disadvantage is: 4 The receiving site for the SSP beam needs to face approximately the horizon when receiving energy at about sunset. That may not have a good solution, for either L2 or L1. Neil

  17. Alienthe said

    Just to illustrate I made and uploaded a diagram illustrating some of the outer orbitological (is that a word??) choices. Drawing is in Inkscape, available on request, PNG hosted on Imageshack:

    (link provided by Imageshack, seems rather big so I’ll leave it to our editor to trim superfluous gunk)

  18. Edawg said

    err.. I dont know where to post this.I noticed one thing when I went lobbying for the NASA budget back in 06 with NSS.Only the states with NASA centers give a flying crap about the NASA budget.If there is ever going to be a national thrust on SSP a political alliance should be formed of key aerospace states (FL,Cali ect..)and once those states are on board with a SSP initive Congress will be around the corner.My crazy 2 cents

  19. Robert said

    Hmm, how about using the “2001: A SPACE ODYSSEY” “monolith(SPS)-as-space settlement-enabler-and-sun-harnesser” imagery with the politicians and the public? Uncompromising Uncles Arthur C. Clarke and Stanley Kubrick may have known exactly what they were planting in our imaginations after they consulted with Peter Glaser over dinner in 1966-68 timeframe (a wild guess). By the way, does anyone know what the Clarke orbit for Jupiter is? (Somewhere between the 3rd and 4th moons maybe?) Do gas giants have Clarke orbits?

  20. Neil Cox said

    The Clark orbit = GEO orbit for rocky planets and moons is the orbital radius where the satellite stays over the same spot on the surface. If gas giant planets (such as Jupiter) have a surface, it is likely too far below the cloud tops to be accesible even by probes and robots. There is, however, a radius which stays over the same spot (with daily weather variations) in the cloud tops.
    2001 and O’Neal type habitats can be either higher or lower than the Clark orbit. We will likely select the lowest radiation altitude reasonably close to gas giant planets, and/or we can have balloon supported habitats near the cloud tops, except for Jupiter which has excessive (for humans) gravity near the cloud tops. Neil

  21. Edawg said

    Oo you made me think of something,I wonder what are the SETI’s guys take on SSP? Would it increase our chances of making first contact!?Either way it would be great for free press coverage on SSP!

    yes,I know im evil =)

  22. Robert said

    I see your thinking on human habitation out there, but I was just thinking of the monolith’s “magical insertion” between moons 3 & 4 in the Stargate sequence in the film “2001”. If viewed sideways, so as to orient the sun to the left and Jupiter to the right, as is the usual orientation when we think of planetary systems, the movement of the SPS/monolith into position to flatly receive the sun’s energy could simply represent a “schematic” of an SPS being moved into Clarke orbit for illustrative purposes. In a departure from describing this scene as a “magical alignment” of moons, planet, and monolith, as film critics have done, I’m going out on a limb and suggesting that this is an educational schematic. One of A.C. Clarke’s last wishes was to get humankind off its “oil kick”. These few seconds of film may be his (and Kubrick’s) way of telling us how to do it. (where’s the smiley face when you need it?)

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