Solar Power Satellites—Full Day Symposium at ESA ESTEC

On 2023-07-14, a one day conference was held as the European Space Agency’s ESTEC (European Space Research and Technology Centre) in Noordwijk, The Netherlands, on the topic “Challenges and Monetization of Power in Space”, discussing the feasibility of delivering power to the Earth from satellites in geostationary orbit which convert solar power (available without interruption at 1.3 kilowatts per square metre) and transmit it to the Earth via a microwave beam.

Space-based solar power was proposed in the 1970s by Peter Glaser (who received U.S. Patent 3,781,647 [PDF] on the concept) and studied over the years by a variety of organisations including NASA, the U.S. Department of Energy, and the Japanese space agency (JAXA). Early studies concluded the cost of launching the required mass from Earth and the infrastructure needed to assemble the large and massive satellites in space would be prohibitive, but with the dramatic drop in launch costs and prospects for further reduction if fully-reusable heavy-lift launchers such as SpaceX’s Starship become available, plus the ability to robotically assemble and service large structures in space made from identical mass-produced modules (see John Mankins’ 2014 book, The Case for Space Solar Power, for examples), has caused the concept to be revisited, motivated in part by the realisation among those who have mastered fifth grade arithmetic that politicans’ and bureaucrats’ announced goal of “net zero by 2050” are utter fantasy without a new, large-scale, source of base load electrical power.

Here is the agenda for the conference, which was sponsored by the SpaceTech programme of the Technical University of Graz, Austria. Click to enlarge the image.

The entire conference was recorded in a video of 7 hours and 18 minutes. I have cued the video in this post to start at the keynote presentation, “The compelling need for Space Based Solar Power and the ESA Solaris Initiative” which starts at the 22 minute mark and is an excellent introduction to the concept for those unfamiliar with it. Here are direct links to the individual talks, which will open in a separate YouTube window.

  • 00:00:00 1- Dietmar Pilz - ESA Technical Director
  • 00:09:00 2- Franz Teschl - Academic Programme Lead for SpaceTech
  • 00:13:30 3- Wiley Larson - Director of SpaceTech
  • 00:22:00 4- Sanjay Vijendran - Keynote: The compelling need for Space Based Solar Power and the ESA Solaris Initiative
  • 01:22:15 5- Mike Snead - Sustainably powering the world with Space Based Solar Power
  • 01:44:45 6- James Cornish - Space Based Solar Power - A future Source of Energy for Europe
  • 02:04:50 7- Namrata Goswami - Space Based Solar Power and Space Policy: Where do Nations Stand?
  • 02:39:00 8- Peter Garettson - The Scale and Possibility of Space Based Solar Power
  • 03:20:45 9- Andreas Vogler & Arthur Woods - Greater Earth Energy Synergies
  • 03:56:45 10- Piotr Marek Kaminski - Airbus Ambition for Power Beaming
  • 04:19:45 11- Vivek Babu - Perovskite Solar Cells for Space Applications
  • 04:41:40 12- Matthias Krieger - The Dilemma and Pathway to Large Scale Solar Manufacturing
  • 05:07:33 13- Robin Nelen - Paraloon, Electrifying Earth, Air and Orbit. An introduction to the Paraloon company, concept and vision
  • 05:28:20 14- Ed Tate - Space Based Solar Power: Physics, Technology, and Economics at Virtus Solis
  • 05:59:00 15- Alejandro Salado - A modern Re-interpretation of Systems Engineering
  • 06:38:05 16 - Nathan Uitenbroek & Nuno Sanos - SpaceTech 2022…2023 Central Case Project Presentation Summary: Lunar Spark - Space Based Power Satellites
  • 07:07:40 - 17 - Panel Session - Key Takeaways from the day
  • 07:18:46 - end

Isn’t this the operative technology of several Bond films?


Due to the inexplicable and unjustified exclusion of the SPECTRE delegation from the planning process for solar power satellites, they are singularly unsuited as Bond villain weapons. The microwave beam used to transmit power to the Earth spreads out substantially along the way from the satellite to the rectifier-antenna (“rectenna”) on Earth, an unavoidable consequence of the antenna size and the microwave frequency used. (An antenna larger than the solar collecting area is impractical from a satellite size, mass, and steering standpoint, and the power beam frequency, around 2.5 Ghz, is chosen for maximum efficiency. Going to a higher frequency gives a smaller beam at Earth, but increases absorption by water vapour in the Earth’s atmosphere and disruption due to clouds, fog, and precipitation.)

The upshot of this is that the energy intensity of the beam for a satellite delivering 2 Gw of power to the grid (around twice the power of a typical fission power reactor) is around 1/4 that of direct sunlight. The frequency is entirely non-ionising, and no more harmful than a mobile phone’s transmitter held near the body. The energy density and frequency have been tested to be safe for animals (including humans) within the beam, and birds and aircraft flying through it. The latter is particularly important, since the rectenna farms can be large, and it would be very inconvenient to declare them no-fly zones. Because the rectenna farm is mostly open space between the individual antennas, if they’re elevated above ground level the terrain below them can be used for growing crops, grazing animals, or even for photovoltaic panels.

It would be possible to use a laser to beam power to the Earth, but in addition to having problems with cloud cover, a two gigawatt continuous duty laser would have a variety of applications other than delivering power to the electrical grid and has not been pursued for that reason.


Harry Stine figured that out years ago. You make the weaponsats seperate and steer power to them. This has downstream effects, see his (writing as Lee Correy) novel Manna for details.


The laziness of the debunks go back to the 1980s and are of a piece with the strawmen versions permitted mind share by the Department of Energy. The present day counterpart is the global warming Hysteria that benefits by raising the noise floor on anything that might solve global warming rather than simply managing whatever that means to the managerial class, as John has previously pointed out in his essay on exercise and dieting.

I’ve previously discussed my coming to loggerheads with Robert Heinlein over this in the early eighties regarding Reagan’s Strategic Defense Initiative. Basically it didn’t seem rational to ignore proposals to utilize lunar materials. It still doesn’t. But in the context of the Reagan Era perhaps there was more going on than meets the eye given the end to the Moon is a Harsh Mistress. If so is it still going on? In that case it may be the only way this will happen at the required scales is something along the lines of Keith Henson’s Sabre proposal.


Here is post by Keith Henson from 2021-11-22 on the “Scale of the problem” topic about the difficulties in using lunar material as originally envisioned by Gerard O’Neill in the 1970s:

… I was deep into moon mining technology. The mass driver turned out to be much more difficult than originally thought, though now it might be relatively easy.

The problem is velocity scatter from the ejection end of the mass driver. I don’t remember the exact numbers, but they would not be hard to find in old papers by Tom Heppenheimer. The source of the problem was the switching speed and jitter of the SCRs that controlled the mass driver coils. Over the last 40 years, this has become perhaps 1000 times better with things like GaN fast power transistors.

In the days when Heppenheimer was working on the problem, the only solution was “achromatic” orbits where (by analogy to lenses that bring different wavelengths to the same focus) mass driver launches from a particular point on the moon with a little variation in velocity wind up (with some scatter) at the same place, the “catcher” out near L2.

I spent close to ten years looking into power satellites built from the earth simply because the complications of a moon mine, mass driver, and all the processing needed to fabricate SPS parts were beyond me.


Right we’ve been over this. What concerns me about the early debunks is it should not have been up to Keith or even the Space Studies Institute. It just seemed like nobody in a position to wield much in the way of resources was serious and that included General Graham’s crew including Robert Heinlein since they were much closer to the Department of Defense bucks and the Strategic Defense Initiative. Given that high gravitational potential energy weapons were part of that initiative I can’t help but Wonder if they didn’t have a conflict of interest.


Sorry Jim, but I am not sure what you refer to with Sabre. Please remind me.

In recent years I have been thinking more about mining an asteroid than mining the moon. Mining Asteroids - HTYP


IIRC, the idea was that in order to deploy SPS mass launched from Earth at the scales required to stop pulling carbon out of the ground, Skylon (hence Sabre engines) must be used due to environmental externalities of rockets.


Ah yes. I talked NOAA into looking at the ozone damage from Skylon flights and even at a million a year, it was acceptable. The paper is linked off the design to cost page. The same study needs to be done for LNG rockets.


I thought everyone had noticed the Musk Derangement Syndrome had already sent tendrils in that direction:


Now that I’ve provide more context for the quoted utterance, maybe I’ll clarify my admittedly speculative conjecture:

DoE engaged in strawman tactics against SPS and SDI didn’t put serious resources into getting lunar mass into cislunar space for the same reason Heinlein and I almost came to blows at a conference circa 1984.

General Graham was stepping on O’Neill not just on concept but in SSI’s service mark by publishing a book titled “High Frontier”. Graham’s appealing argument was you open up frontiers with the military – particularly in the cold war political climate of the Reagan era – so you could utilize the hundreds of billions to do what Keith and SSI couldn’t do:

Explore all the options – not just mass drivers. There were then, and remain now, several, that should be explored. Even mass drivers couldn’t have been written off simply on the basis of Keith’s analysis if we are given to believe that military technology development can come up with advances in components like high speed, high power semiconductor materials. The “New Routes” paper published by O’Neill, Driggers and O’Leary, as inadequate as it may have been in detail, at least got one thing right:

You want to minimize the doubling time of lunar regolith processing via semi-automated telepresence.

OK… now having reiterated all that from our prior conversations…

WHAT IF “Gods Rods” studies determined there was a geopolitical threat represented by space settlement if the military actually did solve the problem of getting lunar mass into cislunar space?

Again… my reference to the end of Heinlein’s “The Moon Is a Harsh Mistress” comes to mind in conjunction with Heinlein’s fervent support of Graham’s, shall we say, “hostile takeover” of O’Neill?

Or, maybe even more speculatively, the military DID put money into getting its hands on nonterrestrial mass for the purpose of weaponizing it.

Either way, Skylon/Sabre may end up being the only way to get large mass flows into space since they’d have to all come from Earth.

PS: While I recognize asteroidal mass is appealing, the problem of time value of money seems a show stopper. Capital utilization rate is a big deal.


Here is a PDF scan of High Frontier: A New National Strategy, published in 1982 by the Heritage Foundation. (This is a 12 megabyte, 200 page file. Many browser PDF plug-ins do not handle such large documents well and get “sticky” and slow when you try to navigate through them. It’s best to download the PDF to your computer and view with a dedicated PDF reader application such as Evince on Linux.)

This document is well worth reading or re-reading if you read it back in the day. There was much more to General Graham’s “High Frontier” than what became SDI. For example, check out the “High Performance Spaceplane Concept” starting on page 129—if ever there was something to get the Air Force “fighter mafia” on board, this was it.


I know the NOAA people who did the study on the ozone damage from Skylon. They have not indicated to me that anyone has asked them to look at the damage from LNG rockets.

They have told me that they would be glad to look into the problem if a rocket company asked. I might add that Reaction Engines was very cooperative with NOAA in that study.

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My influence on this business was never large and SSI was not a big player either.

“written off simply on the basis of Keith’s analysis”

It wasn’t my analysis, credit where due, Tom Heppenheimer did the work and it wasn’t written off either. I was just reporting what he found. I think the extreme cost of the project was (and is) a much larger problem than the technical difficulty of a mass driver.

Agree that telepresence is the way to go. Re asteroids and capital, there is a long transit time involved, but on the other hand, a moon mine is also a long way in the future.

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Although David Criswell hired me for a while at the California Space Institute, I never got very familiar with his lunar solar power proposal. Assuming there is anything to it at all, the short doubling time regolith conversion that Blue Origin seems to be considering may be Bezos’s ace in the hole to beat interest rates.

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Chinese navy is testing the most powerful coil gun ever built…
Coil guns, also known as magnetic accelerators, could bring massive changes to the way wars are fought, paving the way for more devastating attacks on enemy targets…
According to scientists, the coil gun accelerated a 124kg projectile in a firing test to a speed of 700km/h in less than 0.05 seconds. It was the heaviest known projectile to be used in a coil gun experiment. The exact dimensions and maximum range of the weapon remain classified.

And from Sandia a less capable system at 18kg:

I should probably mention at this point that while working on the longitudinal effects of charge momentum, I ran across US Army engineers that were complaining about the way EM gauge freedom is treated due to their experiences with railgun development. One Chinese paper that I chased down involving Aharonov Bohm led me to a brief interaction with that scientist who abruptly cut off communication saying he was sorry but that he could no longer interact with me.


We are drifting some way from solar power satellites – which may be a Good Thing! Still, a random connection: the article points out that “Challenges in materials science have made it difficult to build powerful models even though the technology has been around for decades.” China is the only country which has successfully built an operating commercial Magnetic Levitation train (at the Shanghai airport) – another technology which has been around for decades. And China is reportedly working on upgrading their existing huge High Speed Rail network to a nation-spanning MagLev system.

If the challenge to coil guns is technology rather than physics, then China’s progess on MagLev may have military applications. Just a thought.


And their latest carrier has EMALS. If it works, they would be at most only a few years behind the US.