Experts: Reusable Launch Vehicles Will Make Space Solar Power Affordable

PowerSat's plans for beaming energy from space

PowerSat’s plans for beaming energy from space.

About 20 years ago, NASA conducted a study of space solar power. A friend of mine who was involved said they determined that about six miracles were necessary to make it feasible, the most important being affordable transportation to orbit.

Looks like that miracle is coming closer. Reusable launch vehicles now being developed — along with other advancements over the past two decades — could finally make beaming power down from orbiting satellites economically feasible.

Aviation Week has a lengthy report on a recent space solar panel conference held in Kobe, Japan, where they discussed the prospects for this clean form of power:

“We need a reusable launch system,” says Susumu Sasaki of Tokyo City University, a professor emeritus at JAXA who has studied the relationship between launch costs and the cost of power delivered from space.

Using a 2003 JAXA reference model with a 1-gigawatt station weighing 10,000 tons, Sasaki says power would cost a prohibitive $1.12/kwh at a launch cost to low Earth orbit (LEO) of $10,000 per kilogram. That is in the ballpark of what space launch costs today. Cut that to $1,000 a kilogram—in the ballpark for a reusable launch vehicle (RLV)—and electricity from space drops to 18 cents/kwh.

The SpaceX RLV work, which includes prototype landing legs on the current Falcon 9 taking cargo to the International Space Station (see photo on page 25) and using the rocket’s engines to control the first stage’s return to a splashdown in the Atlantic, is but one development in the fast-changing worldwide spaceflight endeavor that holds promise for space solar power.

Sasaki also cites the need for an orbital transfer vehicle (OTV) to move SPS hardware from LEO to the geostationary Earth orbit (GEO) where space power systems would operate, a development that meshes nicely with NASA’s efforts to develop a high-power solar electric propulsion system for deep-space exploration (AW&ST March 31, p. 26).

Read the full story here.

Wired Magazine also has a story about the original effort by NASA to develop space solar power.

56 Responses to “Experts: Reusable Launch Vehicles Will Make Space Solar Power Affordable”

  1. 1 Michael Vaicaitis

    Well this is just STUPID. The idea of powering Earth from space based solar arrays is stupid on its face and you’d have to be deluded or a moron to conclude otherwise. Nothing can make space solar power “affordable”. Even if the solar arrays were magically transported into space for free, it would still be more expensive than installing the panels on Earth. It’s a shame we can’t generate electricity directly from idiocy, since we seem to have an endless supply.

  2. 2 Tonya

    I’m far from convinced by the idea of SSP as a significant global contributor. Building plants on the ground will remain significantly cheaper and simpler, and there’s masses of available and otherwise useless land.

    America still has vast areas available in the midwest, and Europe has evolving ambitious plans to link up with North Africa. However, Japan through a mix of geography and politics may be the edge case that makes this work.

    As Russia is reminding us again, when it comes to energy, no one wants to be dependent on those who don’t share your interests. Japan is a massive net importer of energy, a situation made so much worse since Fukushima.

  3. 3 Michael Vaicaitis

    There is significant political and social pressure in Japan to restart many of their nuclear power stations. Expect restarts to occur in the near future.

    Solar, in conjunction with batteries (and perhaps capacitors), has the potential to replace all other forms of power, but it would be extremely expensive.

    Nuclear fission using molten salt reactor technology is the simplest, cleanest, safest and cheapest option. It also benefits from being adaptable to anywhere in the solar system and beyond.

    Aneutronic fusion has potential if the engineering issues are not insurmountable.

  4. 4 Aerospike

    Assuming for a moment that launching stuff was indeed free, how on Earth (pun intended) would installing panels on earth still be less expensive than putting them in orbit? Care to explain?

    Last time I checked, there was no weather in space. No snow in winter to cover the panels, no dust and dirt that can settle on them, no clouds to block the sun, no low angled sunlight during winter that result in more light blocked/scattered by the atmosphere. etc.

    Space based solar power basically is just solar power with its biggest drawback removed: unreliable supply.

    It might not be practical for a variety of reasons, but saying that the idea itself is stupid seems more like hyperbole than anything else.

  5. 5 Michael Vaicaitis

    Space based solar Power:
    Radiation from the Sun -> solar panel -> CONVERT to electricity
    -> CONVERT electricity to radiation -> beam through the atmosphere to Earth surface -> solar panel -> CONVERT to electricity.

    Earth based solar power:
    Radiation from the Sun through the atmosphere to Earth surface -> solar panel -> CONVERT to electricity.

  6. 6 Aerospike

    I agree that MSR designs should be the major path forward. However to most politicians as well as the general public the words “nuclear” and “atom(s)” are so frightening, that no serious discussion beyond that words is remotely possible. I have tried to explain MSRs to my friends and families and even those who more or less got my points about the benefits of that design still remained highly skeptical. You could just read from their faces how deeply rooted their fear of nuclear energy is.

  7. 7 Aerospike

    I have never heard of a SBSP design using solar panels on earth? Yes, you have to convert the electricity to radio waves/microwaves and convert those back to electricity on earth but I always assumed that could be done at much higher efficiencies than converting the optical/infrared spectrum to electricity.

    So the additional losses would be an acceptable trade of for a continuous supply.

  8. 8 Michael Vaicaitis

    You’re not wrong. Ignorance and fear are the only significant obstacles.

    However, within the next 10 years there will be molten salt reactors operating. There is a very good chance that Canada will have this tech and China will definitely develop MSR technology.
    Once China has MSRs installed and operating, any country not using MSRs will likely be at a serious economic (and pollution) disadvantage.

  9. 9 Robert Gishubl

    Not sure if SSP to earth will work due to overall cost and environmental concerns on the earth receiving station but it could be used for processing rocket fuel and powering other space industries. More to the point it shows that as launch costs decrease new space based industries become viable increasing the launch demand.

  10. 10 larryj8

    Your sequence is wrong.
    Space solar power generation: Energy from the sun is captured and converted to electricity (either directy via solar cells or by a heat engine). That electricity is transmitted via microwaves to rectanna arrays on the surface (80% efficent). Rectannas are more open than solar panels so they can be located closer to the points of use, meaning lower transmission losses in the power lines. GEO SPS satellites are in sunlight that’s many times more intense than that on the Earth’s surface. The space solar system is easily kept in proper orientation to the sun for maximum efficency, and they’re in sunlight 24/7 except for short periods (72 minutes max) around the vernal and autumnal equinoxes.
    Ground solar panels are typically of fixed orientation so they capture less of the solar energy that hits them. They lose substancial amounts of that energy due to the atmosphere, even more when it’s cloudy, aren’t very effective in the early morning and evening and produce nothing at night. For large scale generation, they have to be installed at remote locations and then send their electricity via power lines that may not exist in that area. Long distance transmission incurs substancial losses.

  11. 11 Tonya

    Valid points. The proponents for SPS sometimes emphasize its benefits as a base load power system in contrast to highly variable renewable generators (wind, land based solar). In that role of a near constant 24/7 power, it displaces nuclear.

  12. 12 Tonya

    Japan’s recent position of being fearful of nuclear power is far from one of ignorance. That is a country that will take a lot of convincing before it trusts its own nuclear industry again.

    The combination of many factors is why I think it may be the single edge case that takes space solar power seriously.

  13. 13 Michael Vaicaitis

    “That electricity is transmitted via microwaves”
    This is not possible in this universe; either you have misspoken yourself or you are under some sort of misapprehension. Microwaves are simply “photonic” radiation, but of a longer wavelength than the majority of the radiation emitted by the Sun.

    Microwaves WILL suffer some absorption in the atmosphere. Atmospheric water is a very good absorber of microwaves. The electricity generated by the solar arrays will be used to generate those microwave, presumably with masers, if you are “beaming” from a distance 57,000km away in GEO. All in all, the laws of thermodynamics will not allow you to reach 80% efficiency. And even using masers, the ground stations will likely need to be tens of kilometres across.

    There is also the thousands of square kilometres of solar arrays in GEO that will be vulnerable to damage from asteroids. Not to mention of course that, even with my earlier comment and reusable rockets, lifting the arrays to space will not be free.

    All that said, my initial assertion that space based solar will never be “affordable” was perhaps an exaggeration. It will not be affordable within the next century and it will never be cost competitive with nuclear fission. Also, with the amount of Uranium and Thorium on Earth and scattered about the solar system, it may well be that nuclear fission is more sustainable than solar. That is if we are to accept present estimates of the Sun’s longevity. And production of all those solar collectors will produce substantially more pollution and toxicity than nuclear fission in molten salt reactors and will, with absolute certainty, lead to more loss of life.

    And for use in space, solar will not be mass competitive for high power applications such as VASIMR.

  14. 14 Michael Vaicaitis

    It could displace nuclear, but at far more cost, damage to the environment and danger to the general population.

  15. 15 Tonya

    From the linked article

    ” there appears to be a growing consensus that microwaves in the 2.45 GHz or 5.8 GHz regions are the preferred wavelengths to pursue because of their all-weather capability, less-rigorous pointing requirements and other factors.

    At those microwave wavelengths, conference participants agreed, there is not a safety risk in beaming huge amounts of power down from GEO-based power satellites. Birds could fly through the beams without injury and the huge rectennas set up to receive the microwaves and convert them into electricity would allow enough sunlight to pass through to the ground to support some kinds of agriculture in the proper climate zones.”

  16. 16 Michael Vaicaitis

    “I have never heard of a SBSP design using solar panels on earth?”
    Fair point. I was lazily using the terms “solar panel” and “solar arrays” as generic terms for radiation collectors and converters.

  17. 17 larryj8

    The 80% efficiency figure is that of the rectenna of converting microwaves to electricity. As pointed out by another writer, the amount of atmospheric microwave absorption depends upon the frequency used. Absorption rates very widely across the spectrum. One problem is that radio astronomers also like those frequencies for the same reason.
    While it’s true that nuclear fission can generate base power cheaper than the best SPS projections, SPS is still cheaper and more reliable than other alternative sources. It isn’t as controversial as nuclear fission (unfortunately) is but you can expect the same Luddites that oppose nuclear (and solar and wind and coal and just about everything else) will object. Those people aren’t just NIMBYs, they’re DBAAW (Don’t Build Anything Any Where) who’d be most happy if everyone was living in caves. There will come a time when the rest of us will have to tell them to shut up.

  18. 18 windbourne

    DARPA, Then DOD, then rescue groups would be able to afford this.
    Diesel in some of the FOBs cost us over $400/gal. I had hoped that DARPA would back small thorium nuke generators for electricity but they did not. Now, this can nor only help lower cost, but be used as a backup system for save naval ships. If a shipvis on a fight and can get power beamed to it, then it fire more lasers and railguns.
    Likewise, the ability to add electricity to disaster areas quickly is competes with water/food/supplies for transportation. This could knock off more than 25% of inbound transportation needs

  19. 19 windbourne

    Actually powering tugs, sats , temp power to is, etc would be useful. Also be able to send some to the moon and mars.

  20. 20 windbourne

    Hence,MRI instead of NMR. That was lame.

  21. 21 windbourne

    Actually, SSP make good sense in some places and situations.

  22. 22 mzungu

    Have fun moving these big things around when space debris comes around….. :D

    Shouldn’t be hard for Putin to throw up some loose bolts up there with a clandestine SSBN launch far off in some places like the Indian Ocean. That should drive us all back to them Russian gas in no time.

  23. 23 mzungu

    Are you talking about the same country that have a few million people living on top of Hiroshima and Nagasaki. :D

  24. 24 mzungu

    Space debris, radiation degradation of materials & electronics, inefficiency of long strings of conversions, maintenance labor cost of astronaut vs trade-school graduate, long commute, long term environmental effect of microwaving various gases in the atmosphere….

  25. 25 mzungu

    All that 24/7 advantage is going to be lost in that long string of transmission conversions. The best DC-microwave-DC conversion efficiency achieved was 50% back in the 90′s.(there is a ESA paper on it, u find in wireless power reference in the Wiki)…that’s not even accounting losts through the atmosphere, and actual out of the lab/real world engineering losts.

  26. 26 Tonya

    There is economic pressure, but the political and social position is overwhelmingly in the opposite direction.

    The subject is frankly toxic, and it will be many generations before anyone will be able to seriously broach subject of nuclear power in Japan. Take the social and political climate in America immediately after three mile island and multiply it by ten to understand the Japanese position today.

  27. 27 Hug Doug

    DARPA probably didn’t back thorium reactors because they were working on polywell fusion reactors. i believe the Navy is currently working on the project now, to the tune of several million dollars per year.

  28. 28 windbourne

    I know, BUT we need an assortment of different energy mechanisms. In addition, thorium is perfect for battle fields, with no meltdowns.
    Besides, I have to wonder about skunkworks fusion device.

  29. 29 Tonya

    It’s easy to be complacent now about what a serious disaster Fukushima was. As has since been revealed, whilst the Government remained calm in public they were drawing up plans to evacuate Tokyo in the event that they couldn’t control the heat escalation in all reactors.

    The Tokyo metropolitan area is around 35 million people.

    The level of corruption and incompetence that investigations have since exposed in Japan’s nuclear industry is truly alarm. The reactors owners (Tepco) tried to abandon the plants in the middle of the crisis, and it was only the direct intervention of the Prime Minister that prevented this. Without his intervention, the worst case scenario would likely have happened.

    It will be many generations until Japan again trusts its nuclear industry, and it’s likely any change in outlook will only occur once an alternative to uranium based fission is available.

  30. 30 Michael Vaicaitis

    The Japanese government, the voters of Tokyo and many others are rather more optimistic and expectant of a nuclear restart than you may realise.

  31. 31 Michael Vaicaitis

    Bussard Polywell, or Follywell more like. Just like tokamaks – wasting their time, efforts and money on magnetic confinement approaches that won’t work can’t work.

  32. 32 Tonya

    To put that in perspective, their current discussion is about whether to restart some of their nuclear reactors. Japan shutdown it’s entire nuclear industry, a total of 54 reactors have been offline at enormous economic cost such was the level of hostility.

    It’s taken three years for the idea of turning any of those back on to be politically acceptable. It’s expected that only about a third of those suspended will eventually see service again. Anything considered too old, unsafe or too near to a population center is out of the question.

    The overall climate is still exceptionally hostile.

  33. 33 Tonya


    As you are probably aware from my comments elsewhere, I’m also a support of nuclear power. I think the biggest obstacle the nuclear industry faces is the common public perception based on irrational fear.

    However, I think rational fear is entirely appropriate and deserved. The world has something a little under 450 nuclear power plants, a significant percentage of which are outdated, obsolete and frankly dangerous.

    A major reason why we still have so many old power plants, is because it has become politically impossible to build their (safer) replacements.

    The evidence that has come to light in Japan following Fukushima is frankly disturbing, and they are right to be distrustful of an industry that appears to have been both corrupt and grossly incompetent.

  34. 34 Michael Vaicaitis

    The only alternative to uranium (233 or 235) based fission is plutonium 239. I’m guessing what you mean is an alternative to solid fuel pressurised water reactors.

    Another point against the likelihood or need of spending 850 trillion dollars developing and deploying space based solar power, is that MSRs will be here in about 10 years or less. It will take 50-100 years before any meaningfully sized space based solar is deployed.

  35. 35 Tonya

    Yes, anything that’s an alternative to what for convenience I’ll simply call “traditional” fission reactors.

    Japan had a variety of systems, I think they were even daft enough to have tried the British Magnox design, which were gas cooled.

  36. 36 Robert Gishubl

    It is not just in the industry but government regulators were partly responsible, both are linked due to certain aspects of Japanese culture. Fukushima was built in 70′s and had passed its original design life. During its re-certification it was known that the original Tsunami protection was inadequate but the regulators did not require improved protection. There is a good article on wikipedia.

    The PWR has proven very safe and reliable providing you follow good practice, it is a public relations issue not a technical issue that prevents widespread affordable safe nuclear power.

  37. 37 Hug Doug

    they certainly are (so far as i can tell from the limited information available) running into some issues with magnetic containment and control of the fusion reaction. but every year the Navy gives them a few hundred thousand dollars more funding, so they are likely actually making progress, rather than stagnating like ITER and similar projects that have cost billions and taken decades.

    it’s not a bad idea to fund alternative fusion methods, anyway.

    and the plus is it’s a much simpler design than a tokamak.

  38. 38 Hug Doug

    well, without knowing much about the design of the device, it’s really hard to say. but as far as i can tell, the High Beta Fusion Reactor is essentially a cylinder, where the polywell is a sphere, and a tokamak is a spinning doughnut. all meant to magnetically contain plasma as it undergoes fusion.

    i wouldn’t hold your breath, since they will very likely run into the same problems of controlling the fusion reaction and maintaining magnetic containment as other attempts have run into, but if they succeed it would be pretty awesome.

  39. 39 mzungu

    Not to be mean, I think you may have underestimate the Japanese love for electronics, or the means to power them.

    The rising cost of importing fossil fuel and fading memories, will eventually restart most if not all those reactors.

  40. 40 Michael Vaicaitis

    For admirers of Elon Musk, who knows a thing or two about solar power and lifting stuff to orbit:

    ““Question: Should not NASA be funding research to make Space Solar Power possible in this time of energy crisis as they did in the 1970’s?

    Elon Musk: No, I don’t believe in space solar power. It will never be competitive with ground solar power. The cost of converting the electron energy to photon energy and then back again on the ground overwhelms the 2X increase in solar incidence. And that’s before you consider the cost of transporting the solar panels and converters to orbit!””

  41. 41 Tonya

    My view comes from Japanese colleagues, and having followed this story quite closely over the last three years.

    I think your view that the Japanese will quickly forget the recent disaster because they have “a love for electronics” is a somewhat dated cliche based on a Western view of Japanese culture.

    Only around a third of the 54 reactors in Japan will likely ever see service again.

  42. 42 mfck

    “Won’t work” is a strong argument from someone calling Polywell a “magnetic confinement” device. Oversimplifying for the sake of rethorics in a technical discussion won’t get you far.

  43. 43 Michael Vaicaitis

    Magnetic confinement is a perfectly accurate description. You can call it inertial electrostatic if you prefer, but like it or not, that is exactly the same thing. As with tokamaks, it uses externally generated magnetic fields to confine (i.e. compress) the plasma. All is well when the confinement field input overwhelms the fusion output. But any hope of reaching a stable net energy output is ruined by plasma instabilities.

    You can’t confinement a net+ energy producing fusion plasma using extrenally generated magnetic fields. Stars overcome this limitation by using a combination of gravitation and internal magnetic fields.

  44. 44 Aerospike

    “The level of corruption and incompetence that investigations have since exposed in Japan’s nuclear industry is truly alarm.”
    I would assume that this would sadly be true for any large scale industry, especially those closely tied to governments (like any powerplant operators). But of course for the general public this is just another case of “we can’t trust nuclear!” …

  45. 45 windbourne

    Musk is right. Under normal conditions, SSP will NEVER make sense.

    However, on earth, for things like a FOB (forward operating base), where it costs $200-400/gal for diesel that runs generators, OR for disaster areas, or for providing back-up/enhancement power to USN ships, this would be dirt cheap.

    These are areas that absolutely should be sought after.

  46. 46 windbourne

    Unless of course you have them up higher and then relay the energy.
    However, during a war, that would be a big loser.
    That is also why I believe it is a mistake to EVER depend on wind/solar for more than say 15%. Weather modification could do a lot of damage to somebody.

  47. 47 windbourne

    what is really needed is to replace all of those with reactors that are not only safe, but will use the old waste.

  48. 48 windbourne

    Yeah, I can not image that something like thorium could be used :)

  49. 49 windbourne

    Well, apparently, skunkworks is working towards it.

  50. 50 windbourne

    One other thing about SPSS that few every think about is that it is adding EXTRA energy, or heat to the earth. If a significant amount were to go up, then it would be realized that we have issues. BIG issues.

  51. 51 mzungu

    Yeah, it’s a niche power source. Space debris up in GEO had not gather much headlines, but considering how concentrated things are up there, I am surprised it been peaceful up there. but if there is more construction up there, who knows…it’ll get interesting.

    and then there is that amount of spectrum noises it’ll generate, good luck getting those com-sat people to sign off on this…. specially for countries that owns those slots… hhahaa.

    I don’t even know why I am talking about SPS, it’s like talking about flying cars….such a waste of time. :D

  52. 52 Michael Vaicaitis


  53. 53 Michael Vaicaitis

    Thorium is the feed “fuel” that breeds to Uranium 233 which is the actual fuel. IOW, a Thorium reactor IS a Uranium 233 reactor.

  54. 54 mzungu

    All those rectenna makes for big targets for FOB, don’t you think? The USN have the capability to build nuclear reactors that will prob fit into a shipping container, so I doubt they need it for “power”. That SPS would makes for good electronic warfare jammers for brute force jamming for enemy fleets.

  55. 55 mzungu

    The Japanese started their nuclear power program not 10 years after the A-bombs were dropped, because they realize/know that one of the reason they lost the war is because they import all their oil, and towards the end of WWII, their Navy can’t move because of shortage of fuel.

    So, with their current political climate with China and their other neighbors, and how China is expanding their navy and securing energy sources deals from around the world…. I think it’ll take less than 10 years to over come their fears this time.

  56. 56 Tonya

    It took about 35 years to break ground on the first new civil reactor in the United States after the comparatively minor Three Mile Island.

    Democracies scare easily and Japan is a very different country today to what it was sixty years ago.

    The entire Japanese nuclear industry has now been shut down for three years, representing around 20% of the countries energy mix. The cost to their economy of doing that has been immense, a powerful indicator of the level of opposition. It now looks probable that two thirds of those plants will be written off, with just one in three being slowly reactivated over this decade.

    To connect back to the title story, I don’t think Japan will consider nuclear again for many generations and only then when vastly safer designs have been proven. The country is throwing huge amounts of money into renewable energy and proposing to increase it’s already ambitious targets. That is the simple reason why they are the edge case that may attempt space based solar before anyone else. They have the right mix of economic and political need.

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