Orbits and lighting levels for artificial moon satellite over China

China Daily provided more details about the artificial full moon mirror satellite over Chengdu.

This article is referring to Chinese statements about their mirror moonlight system and referencing a presentation “Mirrors in Dawn Dusk Orbit for Low-Cost Terrestrial Solar Electric Power in the Evening” at the AIAA tech conference on 2013. The work in China has to obey the physics and orbital mechanics of such light reflecting systems. Lewis M. Fraas JX Crystals and
Billy Derbes and Arthur Palisoc of L’Garde Tustin, CA wrote the AIAA paper.

China plans to put an artificial moon in orbit above Chengdu, capital of Sichuan province, from the Xichang Satellite Launch Center in Sichuan by 2020. If the launch proves successful, three more such objects will be launched in 2022, Wu Chunfeng, head of Tian Fu New Area Science Society in Chengdu.

Astronomers complain that the artificial moon mirrors would make light pollution 50 times worse.

The brightest possible Full Moon under ideal conditions has an illuminance of about 0.3 lux, but it’s often just 0.15-0.2 lux. The mirror moons would have 1.6 lux.

The sky brightness over central Chengdu due to skyglow in is predicted to be 5.43 mcd/m2, or about 18.25 magnitudes per square arcsecond, using satellite data obtained in 2015.

The city currently has 0.034 lux. The new mirror satellites will increase it by 47 times.

Full daylight is 10752 lux. 1 lux equals 1 Lumen per square meter. One candle is 12.57 lumens. A street light has 10 lux.

The Harbin Institute of Technology and China Aerospace Science and Industry Corp are also involved in developing Chengdu’s illumination satellites.

The man-made moon is essentially an illumination satellite designed to complement the moon at night, though it is predicted to be eight times brighter, the scientist added.

This is due to the object’s planned orbit about 500km above Earth-much closer than the 380,000km distance to the moon, Mr Wu said.

Nextbigfuture notes that a 500-kilometer orbit would not be that good for lighting a city. This is likely only the orbit for the test satellite.

I do not think the 2020 test system will reach the 1.6 lux lighting level. I think the 2020 system will be smaller. The three satellite system for 2022 will bigger in order to reach the desired lighting levels. If the systems are at 500-kilometer orbits then they will not be lighting the city throughout much of the night.

Almost doubling the solar power from ground sites and halving the cost

A Dawn-Dusk Orbit at 1000 kilometers would be better. Dawn-Dusk orbits were proposed by JX Crystals. JX is a US company.

18 mirror satellites in a sun-synchronous orbit at an altitude of approximately 1000 km. The Chengdu plan is to have 3 mirror satellites follow up in 2022.

In 1979, Dr. Krafft Ehricke proposed the Power Soletta constellation of satellites in an orbit 4200 km in altitude to a 1200 sq km site in Western Europe. The mirrors in orbit at an altitude of 4200 km gives a sunspot diameter on earth of 42 km with a corresponding area of 1385 sq km. This explains the 1200 sq km solar field size for the Power Soletta concept. This also means that in order to produce an intensity of sunlight on earth equivalent to the normal daylight sun intensity, the area of the 3 mirrors shown beaming power down would have to be 1385 sq km and the area of the 10 mirror satellites in the constellation would have to be 4617 sq km. The Power Soletta mirror satellites were also in the Van Allen radiation belt.

The Chengdu nighttime lighting is 6000 times less than normal daylight. 4200-kilometer altitude would still require about 600-800 meter diameter mirrors.

The 1000 kilometer mirror would only need about 150 to 200-meter diameter mirrors. It would likely need to be some kind of boom deployment of thin film with reflective material.

The physics determine it needs to be big.
Orbital mechanics indicate that you would have to place them at certain altitudes depending upon the times you want coverage.

Solar energy available to these ground sites can be increased from an average of 7 kWh per sq meters per day without the space mirrors to 12 kWh per sq meters per day with the space mirrors. The additional 5 kWh per square meters per day will be provided in the early morning and evening hours.

The illuminated sunlight spot size on the earth from a 1000 kilometer altitude mirror satellite is about 10 km in diameter instead of the 42 km spot size associated with the Power Soletta configuration. The 10-kilometer diameter was mentioned in the press releases.

Scaling up 6000 times from the megacity moonlighting to nighttime lighting level of large ground solar power plants. Either the mirrors get bigger or you get a lot more of them or both.

Test satellite will be one-fifth normal street lights

“But this is not enough to light up the entire night sky,” he said. “Its expected brightness, in the eyes of humans, is around one-fifth of normal street lights.”

The location and brightness of the light beam can be changed, and its coverage accuracy can fall within a few dozen meters, he said.

The artificial moon might replace some street lights in the urban area, thus conserving energy.

Mr Wu estimated Chengdu could save around 1.2 billion yuan (US$170 million) in electricity annually if the artificial moon illuminated 50 sq km of the city.

The extra light can shine into disaster zones during blackouts, thus aiding relief and rescue efforts.

The mirrors can be adjusted for luminosity, and can be completely turned off when needed. However, less light from the satellite will reach the ground if the sky is overcast.

“The first moon will be mostly experimental, but the three moons in 2022 will be the real deal with great civic and commercial potential,” Mr Wu said.

The three new man-made moons can take turns reflecting sunlight, as they will not always be in the best position relative to the sun, and together they can illuminate an area of around 3,600 to 6,400 sq km on Earth for 24 hours if desired.

This statement suggests that the full-time systems would be at higher altitude orbits. The higher the altitude then the larger the systems have to be.

97 thoughts on “Orbits and lighting levels for artificial moon satellite over China”

  1. I remember reading about something like this in 1978 or so. I think it was called SOLARES, can’t be sure since it was long ago. The idea was to put thousands of these mirror satellites into relatively closed by orbit. They would rotated to reflect light to solar power plants on earth. They could also light cities and farms. The satellites would be light and cheap but lofting the required number would be still be expensive. A mention side effect would be a permanent glimmer in the sky caused by the satellites rotating to their next target.

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  2. Oh YES, let’s ruin a beautiful night sky. And think of the pretty glow as the mirrors “set” when they leave the sun’s light. There would be the colors of pollution in the after glow.

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  3. I remember reading about something like this in 1978 or so. I think it was called SOLARES can’t be sure since it was long ago. The idea was to put thousands of these mirror satellites into relatively closed by orbit. They would rotated to reflect light to solar power plants on earth. They could also light cities and farms. The satellites would be light and cheap but lofting the required number would be still be expensive. A mention side effect would be a permanent glimmer in the sky caused by the satellites rotating to their next target.

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  4. Oh YES let’s ruin a beautiful night sky. And think of the pretty glow as the mirrors set”” when they leave the sun’s light. There would be the colors of pollution in the after glow.”””

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  5. The low orbits will be problematic, because such a huge light-weight membrane will be slowed down a lot by drag in the outer extends of the atmosphere. And I wonder if the membrane could be made slightly parabolic. Then it can be smaller in higher orbits. Also, from a certain size it should be more efficient to have three satellites pulling on three corners of the membrane, instead of a central satellite and booms.

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  6. So… what’s the operating altitude again? It matters in three senses: (1) the altitude determines the satellite’s period (sec/orbit, min/orbit, hr/orbit…) (2) in turn it determines the illuminated spot size on Earth (3) and from those, plus desired illumination, the size of the reflector № 1 in particular follows formula (P = 2π√((Re + altitude)³ / (Ge • Re²)) ) Below I assume the article’s “about 8× the intensity of full moonlight” For instance: ⇒ Altitude = 500 km (lowest reasonable altitude) ⇒ P = 5,669 sec → 94.5 min → 1.57 hr → 15.2 orbits/day ⇒ S = 4.6 km diameter ⇒ M = 8 m diameter, 90% reflectance ⇒ Altitude = 1000 km ⇒ P = 6,300 sec → 105 min → 1.75 hr → 13.7 orbits/day ⇒ S = 9.2 km diameter ⇒ M = 16 m diameter, 90% reflectance ⇒ Altitude = 2400 km ⇒ P = 8,179 sec → 136 min → 2.27 hr → 10.6 orbits/day ⇒ S = 22 km diameter ⇒ M = 38 m diameter, 90% reflectance The point is, that naturally everything has to scale with physics. (actually trigonometry) More interesting operating points: ⇒ Altitude = 8000 km … to maintain illumination for most of night ⇒ P = 17,150 sec → 286 min → 4.77 hr → 5.0 orbits/day ⇒ S = 73 km diameter ⇒ M = 125 m diameter, 90% reflectance ⇒ Altitude = 35,840 km … “geosynchronous”, never changing position in sky ⇒ P = 86,400 sec → 1,440 min → 24 hr → ⇒ S = 328 km diameter ⇒ M = 560 m diameter, 90% reflectance Then there is the idea of a “sun synchronous” orbit. I’ve been thinking about that some, and while I resist looking it up on Google (out of principle), I think that a cunning orbit would be one such that the angle of the satellite’s mirror might contrive to be at the RIGHT angle to reflect the sun exactly at the spot on Old Dirt where the artificial Moonlight x 8 is supposed to illuminate. … goat thinks … Realizes that this is possible for nearly all orbits. There is always some relative to sun-and-earth rotational rate that’d ensure the right angle. But, for all orbits including the equatorial “geostationary” on

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  7. The low orbits will be problematic because such a huge light-weight membrane will be slowed down a lot by drag in the outer extends of the atmosphere.And I wonder if the membrane could be made slightly parabolic. Then it can be smaller in higher orbits. Also from a certain size it should be more efficient to have three satellites pulling on three corners of the membrane instead of a central satellite and booms.

    Reply
  8. So… what’s the operating altitude again? It matters in three senses:(1) the altitude determines the satellite’s period (sec/orbit min/orbit hr/orbit…)(2) in turn it determines the illuminated spot size on Earth(3) and from those plus desired illumination the size of the reflector№ 1 in particular follows formula (P = 2π√((Re + altitude)³ / (Ge • Re²)) )Below I assume the article’s about 8× the intensity of full moonlight””For instance:⇒ Altitude = 500 km (lowest reasonable altitude)⇒ P = 5″”669 sec → 94.5 min → 1.57 hr → 15.2 orbits/day⇒ S = 4.6 km diameter⇒ M = 8 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectance⇒ Altitude = 1000 km⇒ P = 6300 sec → 105 min → 1.75 hr → 13.7 orbits/day⇒ S = 9.2 km diameter⇒ M = 16 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectance⇒ Altitude = 2400 km⇒ P = 8179 sec → 136 min → 2.27 hr → 10.6 orbits/day⇒ S = 22 km diameter⇒ M = 38 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectanceThe point is that naturally everything has to scale with physics. (actually trigonometry) More interesting operating points: ⇒ Altitude = 8000 km … to maintain illumination for most of night⇒ P = 17150 sec → 286 min → 4.77 hr → 5.0 orbits/day⇒ S = 73 km diameter⇒ M = 125 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectance⇒ Altitude = 35″”840 km … “”””geosynchronous”””””” never changing position in sky⇒ P = 86400 sec → 1440 min → 24 hr → ⇒ S = 328 km diameter⇒ M = 560 m diameter”” 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectanceThen there is the idea of a “”””sun synchronous”””” orbit. I’ve been thinking about that some”” and while I resist looking it up on Google (out of principle) I think that a cunning orbit would be one such that the angle of the satellite’s mirror might contrive to be at”

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  9. Unlike so many bad ideas, this is easily reversed. If the idea turns out useless or too troublesome, then just don’t launch any more and let the existing ones be deorbited. Like they never existed,

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  10. I like it. This is step one towards solar power satellites. The first step being just a little ambitious from current tech, but not the huge leap required to go all the way to 1 GW power beaming.

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  11. While orbital mirrors reflecting lasers isn’t ridiculous, that would be a completely different sort of mirror. The huge metallized film things being discussed would never have the accuracy, response time or focus to be laser weapons.

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  12. You might like the technical side but you may cry when you look at the economics. Basically what you are doing is extending the operating hours of a solar PV farm. This system”” will give you an additional 2 hours”” 3 at most. So a 40-50{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} boost in output (Fraas the inventor estimated a 70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} boost but that is 100{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} optimal). That means IF the build and operating cost of the beam system is LESS than the expected boost in output (revenue) then you MAYBE are good to go. If not it’s not worth it. All this boils down to adding the build/launch/maintenance/operating cost of the beam system into your solar PV spreadsheet. Current new large-scale commercial PV array systems are pricing in at about $23-25/MWh and estimates are $20/MWh by 2019/20. The usual project IRR for such a system is about 3.5-5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} 7{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} on the high side. That is LOWER than commercial WACC ie capital destroying. That means the difference needs to be subsidized. E.g. none of the Gulf states new very large solar projects are built commercially they are all loss-making and therefore heavily subsidized. It’s one of the things the renewable industry hates to talk about – that costs have been driven down so low that investors run away unless tax money is deployed. Now”” the inventor (Fraas) claims the “”””marginal”””” cost of the space beam will be about 10{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of a solar array all-in cost”” at least the cost of sending it into space not the construction costs or other monitoring systems eventual maintenance etc. I haven’t seen any estimates on total sun beam costs but can imagine it’s at least 2-3x the cost of sending it”

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  13. Unlike so many bad ideas this is easily reversed. If the idea turns out useless or too troublesome then just don’t launch any more and let the existing ones be deorbited. Like they never existed

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  14. I like it.This is step one towards solar power satellites. The first step being just a little ambitious from current tech but not the huge leap required to go all the way to 1 GW power beaming.

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  15. While orbital mirrors reflecting lasers isn’t ridiculous that would be a completely different sort of mirror. The huge metallized film things being discussed would never have the accuracy response time or focus to be laser weapons.

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  16. You might like the technical side, but you may cry when you look at the economics. Basically, what you are doing is extending the operating hours of a solar PV farm. This “system” will give you an additional 2 hours, 3 at most. So a 40-50% boost in output (Fraas, the inventor, estimated a 70% boost but that is 100% optimal). That means IF the build and operating cost of the beam system is LESS than the expected boost in output (revenue), then you MAYBE are good to go. If not, it’s not worth it. All this boils down to adding the build/launch/maintenance/operating cost of the beam system into your solar PV spreadsheet. Current new large-scale commercial PV array systems are pricing in at about $23-25/MWh and estimates are $20/MWh by 2019/20. The usual project IRR for such a system is about 3.5-5%, 7% on the high side. That is LOWER than commercial WACC, ie capital destroying. That means the difference needs to be subsidized. E.g., none of the Gulf states new very large solar projects are built commercially, they are all loss-making and therefore heavily subsidized. It’s one of the things the renewable industry hates to talk about – that costs have been driven down so low that investors run away, unless tax money is deployed. Now, the inventor (Fraas) claims the “marginal” cost of the space beam will be about 10% of a solar array all-in cost, at least the cost of sending it into space, not the construction costs or other monitoring systems, eventual maintenance etc. I haven’t seen any estimates on total sun beam costs, but can imagine it’s at least 2-3x the cost of sending it into space if not more. It appears that the additional costs of the sun beam doesn’t really help the economics that much and just might be value-destroying. The other problem of course is where to beam the light. You probably want to use high-efficiency places. Too bad these places are far away from where the power is needed. The opportunity costs need to be looked at too. As of 2018, c

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  17. Seems like this thing – especially at the larger scales – might be better called a “Kessler Cascade initiating anti-Satellite Weapon”.

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  18. PS: small transcription error. If the nominal 8 × moon level illumination is achieved with a 15.4 m diameter 90% reflector, then 500,000× Moon would be exactly the above numbers, but not as I typed them. 11,500,000 m² and 3,800 m diameter.

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  19. Dunno. You’re basically right of course. As is DoctorPat. Its a good start. But there are so many contrary optimizations in play. Makes it hard to pin down what really might be an optimal tactical roll-out. For instance, there is a half-a-million-to-ONE difference in producing wan street night-lighting and competently illuminating a 20 kilometer-in-diameter solar far at 0.7× to 1.5× nominal noon sunlight. ⇒ 500,000× That is a BIG difference in the size of the reflector “up there”. Like … 500,000× difference. Consider for the instance of the thing I modelled in the other article. A 90% efficient reflector in a 1,000 km altitude orbit, delivering roughly 8× nominal full-moon street lighting levels of illumination. The 10-to–15 km ‘spot’ (really a conic section of ellipsoidal projection shape) from the 1,000 km orbit required a 90% reflectance mirror of 186 m² (whate’r the shape), but if circular then 15.4 m in diameter. About 50 feet in diameter. Now, scale that 500,000× to make it a more-or-less-one-SOL illumination. Same orbit. ⇒ 15.4 × √( 500,000× ) → 11,500,000 m² AREA ⇒ √( 11,500,000 / π ) × 2 → 3,800 m Diameter Well I tell you this: a 3,800 m (2.4 mile!!!) diameter almost-perfectly-flat mirror in space is NOT going to be lofted any time soon, no matter how brilliant (ahem) the cost-effectiveness “space spider” calculations. Moreover, lest we forget, in order to get 1 Sol illumination, the “thing in the sky” is going to have to have a fixible extent (i.e. when you look up, there it is… ‘this big’) the SAME size as the sun itself. And it needs to be a focussed image of the sun. Can’t be a flat mirror. At all. So a 3,800 meter parabolically curved mirror. Thankfully it doesn’t need astronomical-observation perfection. Just “kind-of-sort-of” parabolic is OK. After all, its just for solar power (on Earth). Thankfully, the whole structure doesn’t need to slew about in order to project the Sun’s image down here on Dirt. Can’t

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  20. Seems like this thing – especially at the larger scales – might be better called a Kessler Cascade initiating anti-Satellite Weapon””.”””

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  21. PS: small transcription error. If the nominal 8 × moon level illumination is achieved with a 15.4 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflector then 500000× Moon would be exactly the above numbers but not as I typed them. 11500000 m² and 3800 m diameter.”

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  22. Dunno.You’re basically right of course. As is DoctorPat.Its a good start.But there are so many contrary optimizations in play. Makes it hard to pin down what really might be an optimal tactical roll-out. For instance there is a half-a-million-to-ONE difference in producing wan street night-lighting and competently illuminating a 20 kilometer-in-diameter solar far at 0.7× to 1.5× nominal noon sunlight. ⇒ 500000×That is a BIG difference in the size of the reflector “up there”. Like … 500000× difference.Consider for the instance of the thing I modelled in the other article. A 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} efficient reflector in a 1000 km altitude orbit delivering roughly 8× nominal full-moon street lighting levels of illumination. The 10-to–15 km ‘spot’ (really a conic section of ellipsoidal projection shape) from the 1000 km orbit required a 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectance mirror of 186 m² (whate’r the shape) but if circular then 15.4 m in diameter. About 50 feet in diameter. Now scale that 500000× to make it a more-or-less-one-SOL illumination. Same orbit. ⇒ 15.4 × √( 500000× ) → 11500000 m² AREA⇒ √( 11500000 / π ) × 2 → 3800 m DiameterWell I tell you this: a 3800 m (2.4 mile!!!) diameter almost-perfectly-flat mirror in space is NOT going to be lofted any time soon no matter how brilliant (ahem) the cost-effectiveness “space spider” calculations. Moreover lest we forget in order to get 1 Sol illumination the “thing in the sky” is going to have to have a fixible extent (i.e. when you look up there it is… ‘this big’) the SAME size as the sun itself. And it needs to be a focussed image of the sun. Can’t be a flat mirror. At all.So a 3800 meter parabolically curved mirror. Thankfully it doesn’t need astronomical-observation perfection.Just “kind-of-sort-of” parabolic is OK. After all its just

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  23. Here’s the thing… What does the space command center need to achieve with that projected image of the sun (PIOTS)? • (1) accurate tracking of the satellite relative to Sol • (2) accurate vectoring of mirror to ‘hit’ the target city¹ dead on. • (3) fairly rapid repositioning as “the next city” is queued up. • (4) sundry satellite maintenance: reaction fuel levels, all that. № 1 … Satellites stay in stabile orbits perhaps for millennia when high enough. 1,000 km up won’t cut it. Perhaps 5,000 km would do. The PIOTS would be about 45 km diameter. № 2 … While the PIOTS would likely be quite a bit larger than the target city, you don’t exactly want it wandering hundres of kilometers off the center of the city. Yet, there is “constant fantastic math” going on in controlling the (Sol → satellite orbit → spinning Earth → Earth seasonal inclination → target city/farm/) angles of the membrane mirror azimuth. Because at 5,000 km, you’ve got a minimum 45 km diameter PIOTS, having an area of 1,600 km² or 160,000 hectares. Maybe for China’s megacities this is OK. № 3 … Again — think about size. The 77 meter (hexagonal membrane, not triangular) diameter satellite needs to be vectored to this mutually moving system in a fashion quite different from the large-coverage GPS constellation. The vectoring changes every second. The quarter-radius of 45 km diameter (5 km) requires positioning accuracy of 0.065°. Wow. While this ought to be “not too hard” with the satellite gyroscopes methods, the accumulated inertial torque periodically needs to be “unspun” by jetting rocket fuel, out. Which changes the inertial moment of the bird, changing ALL calculations for how to revector it. Also, it might significantly change its orbit. ________________________________________ NOW … think of a space reflector that is large enough to deliver 1.5 Sol illumination to Earth. Same 5,000 km orbit? Maybe not, 45 km PIOTS is too large but for the most ridiculously oversized sola

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  24. Yeah, Fraas talks about 1-sol power while Chengdu-tribe talks about moonlight (through the terrible smog there). Some more moonlight is more or less useless for PV, and I have to say is useless for street lighting needs too. Full moon light is at best about 0.1 lux. Guidelines for local street lighting ranges from about 14 lux to 26 lux on pavement depending on traffic, highways are rated about 6-9 lux, “public areas in dark surroundings” requires 20-50 lux. The latter is at least 200x brighter than moonlight. Quite a big mirror, just for street lighting. Besides, ambient urban lights (like in Chengdu) easily drowns out any moonlight. As you probably also know, clear sunlight on the ground at sea level is about 10,000 lux. The whole “moonlight” thingy is fake news. Chengdu has a science city and building the “Tianfu New Area” a Silly Valley type city within a city (megacity, these projects are HUGE). Mostly deserted at this point (but plenty of street lights!!). I was there last winter. Now and then they “report” all these fantastic science-fictiony new developments from the project. This is one of them. The unit that announced this “initiative” is the same company that builds the J-20 stealth fighter…..’nuff said.

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  25. Here’s the thing…What does the space command center need to achieve with that projected image of the sun (PIOTS)? • (1) accurate tracking of the satellite relative to Sol• (2) accurate vectoring of mirror to ‘hit’ the target city¹ dead on.• (3) fairly rapid repositioning as “the next city” is queued up.• (4) sundry satellite maintenance: reaction fuel levels all that. № 1 … Satellites stay in stabile orbits perhaps for millennia when high enough. 1000 km up won’t cut it. Perhaps 5000 km would do. The PIOTS would be about 45 km diameter.№ 2 … While the PIOTS would likely be quite a bit larger than the target city you don’t exactly want it wandering hundres of kilometers off the center of the city. Yet there is “constant fantastic math” going on in controlling the (Sol → satellite orbit → spinning Earth → Earth seasonal inclination → target city/farm/) angles of the membrane mirror azimuth. Because at 5000 km you’ve got a minimum 45 km diameter PIOTS having an area of 1600 km² or 160000 hectares. Maybe for China’s megacities this is OK. № 3 … Again — think about size. The 77 meter (hexagonal membrane not triangular) diameter satellite needs to be vectored to this mutually moving system in a fashion quite different from the large-coverage GPS constellation. The vectoring changes every second. The quarter-radius of 45 km diameter (5 km) requires positioning accuracy of 0.065°. Wow.While this ought to be ot too hard”” with the satellite gyroscopes methods”” the accumulated inertial torque periodically needs to be “unspun” by jetting rocket fuel out. Which changes the inertial moment of the bird changing ALL calculations for how to revector it. Also it might significantly change its orbit. ________________________________________NOW … think of a space reflector that is large enough to deliver 1.5 Sol illumination to Earth. Same 5000 km orbit? Maybe not 45 km PIOTS is too large but for the most ridiculously”

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  26. Yeah Fraas talks about 1-sol power while Chengdu-tribe talks about moonlight (through the terrible smog there). Some more moonlight is more or less useless for PV and I have to say is useless for street lighting needs too. Full moon light is at best about 0.1 lux. Guidelines for local street lighting ranges from about 14 lux to 26 lux on pavement depending on traffic highways are rated about 6-9 lux public areas in dark surroundings”” requires 20-50 lux. The latter is at least 200x brighter than moonlight. Quite a big mirror”” just for street lighting. Besides ambient urban lights (like in Chengdu) easily drowns out any moonlight. As you probably also know clear sunlight on the ground at sea level is about 10″”000 lux. The whole “”””moonlight”””” thingy is fake news. Chengdu has a science city and building the “”””Tianfu New Area”””” a Silly Valley type city within a city (megacity”””” these projects are HUGE). Mostly deserted at this point (but plenty of street lights!!). I was there last winter. Now and then they “”””report”””” all these fantastic science-fictiony new developments from the project. This is one of them. The unit that announced this “”””initiative”””” is the same company that builds the J-20 stealth fighter…..’nuff said.”””

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  27. Here’s the thing… What does the space command center need to achieve with that projected image of the sun (PIOTS)? • (1) accurate tracking of the satellite relative to Sol • (2) accurate vectoring of mirror to ‘hit’ the target city¹ dead on. • (3) fairly rapid repositioning as “the next city” is queued up. • (4) sundry satellite maintenance: reaction fuel levels, all that. № 1 … Satellites stay in stabile orbits perhaps for millennia when high enough. 1,000 km up won’t cut it. Perhaps 5,000 km would do. The PIOTS would be about 45 km diameter. № 2 … While the PIOTS would likely be quite a bit larger than the target city, you don’t exactly want it wandering hundres of kilometers off the center of the city. Yet, there is “constant fantastic math” going on in controlling the (Sol → satellite orbit → spinning Earth → Earth seasonal inclination → target city/farm/) angles of the membrane mirror azimuth. Because at 5,000 km, you’ve got a minimum 45 km diameter PIOTS, having an area of 1,600 km² or 160,000 hectares. Maybe for China’s megacities this is OK. № 3 … Again — think about size. The 77 meter (hexagonal membrane, not triangular) diameter satellite needs to be vectored to this mutually moving system in a fashion quite different from the large-coverage GPS constellation. The vectoring changes every second. The quarter-radius of 45 km diameter (5 km) requires positioning accuracy of 0.065°. Wow. While this ought to be “not too hard” with the satellite gyroscopes methods, the accumulated inertial torque periodically needs to be “unspun” by jetting rocket fuel, out. Which changes the inertial moment of the bird, changing ALL calculations for how to revector it. Also, it might significantly change its orbit. ________________________________________ NOW … think of a space reflector that is large enough to deliver 1.5 Sol illumination to Earth. Same 5,000 km orbit? Maybe not, 45 km PIOTS is too large but for the most ridiculously oversized sola

    Reply
  28. Here’s the thing…What does the space command center need to achieve with that projected image of the sun (PIOTS)? • (1) accurate tracking of the satellite relative to Sol• (2) accurate vectoring of mirror to ‘hit’ the target city¹ dead on.• (3) fairly rapid repositioning as “the next city” is queued up.• (4) sundry satellite maintenance: reaction fuel levels all that. № 1 … Satellites stay in stabile orbits perhaps for millennia when high enough. 1000 km up won’t cut it. Perhaps 5000 km would do. The PIOTS would be about 45 km diameter.№ 2 … While the PIOTS would likely be quite a bit larger than the target city you don’t exactly want it wandering hundres of kilometers off the center of the city. Yet there is “constant fantastic math” going on in controlling the (Sol → satellite orbit → spinning Earth → Earth seasonal inclination → target city/farm/) angles of the membrane mirror azimuth. Because at 5000 km you’ve got a minimum 45 km diameter PIOTS having an area of 1600 km² or 160000 hectares. Maybe for China’s megacities this is OK. № 3 … Again — think about size. The 77 meter (hexagonal membrane not triangular) diameter satellite needs to be vectored to this mutually moving system in a fashion quite different from the large-coverage GPS constellation. The vectoring changes every second. The quarter-radius of 45 km diameter (5 km) requires positioning accuracy of 0.065°. Wow.While this ought to be ot too hard”” with the satellite gyroscopes methods”” the accumulated inertial torque periodically needs to be “unspun” by jetting rocket fuel out. Which changes the inertial moment of the bird changing ALL calculations for how to revector it. Also it might significantly change its orbit. ________________________________________NOW … think of a space reflector that is large enough to deliver 1.5 Sol illumination to Earth. Same 5000 km orbit? Maybe not 45 km PIOTS is too large but for the most ridiculously”

    Reply
  29. Yeah, Fraas talks about 1-sol power while Chengdu-tribe talks about moonlight (through the terrible smog there). Some more moonlight is more or less useless for PV, and I have to say is useless for street lighting needs too. Full moon light is at best about 0.1 lux. Guidelines for local street lighting ranges from about 14 lux to 26 lux on pavement depending on traffic, highways are rated about 6-9 lux, “public areas in dark surroundings” requires 20-50 lux. The latter is at least 200x brighter than moonlight. Quite a big mirror, just for street lighting. Besides, ambient urban lights (like in Chengdu) easily drowns out any moonlight. As you probably also know, clear sunlight on the ground at sea level is about 10,000 lux. The whole “moonlight” thingy is fake news. Chengdu has a science city and building the “Tianfu New Area” a Silly Valley type city within a city (megacity, these projects are HUGE). Mostly deserted at this point (but plenty of street lights!!). I was there last winter. Now and then they “report” all these fantastic science-fictiony new developments from the project. This is one of them. The unit that announced this “initiative” is the same company that builds the J-20 stealth fighter…..’nuff said.

    Reply
  30. Yeah Fraas talks about 1-sol power while Chengdu-tribe talks about moonlight (through the terrible smog there). Some more moonlight is more or less useless for PV and I have to say is useless for street lighting needs too. Full moon light is at best about 0.1 lux. Guidelines for local street lighting ranges from about 14 lux to 26 lux on pavement depending on traffic highways are rated about 6-9 lux public areas in dark surroundings”” requires 20-50 lux. The latter is at least 200x brighter than moonlight. Quite a big mirror”” just for street lighting. Besides ambient urban lights (like in Chengdu) easily drowns out any moonlight. As you probably also know clear sunlight on the ground at sea level is about 10″”000 lux. The whole “”””moonlight”””” thingy is fake news. Chengdu has a science city and building the “”””Tianfu New Area”””” a Silly Valley type city within a city (megacity”””” these projects are HUGE). Mostly deserted at this point (but plenty of street lights!!). I was there last winter. Now and then they “”””report”””” all these fantastic science-fictiony new developments from the project. This is one of them. The unit that announced this “”””initiative”””” is the same company that builds the J-20 stealth fighter…..’nuff said.”””

    Reply
  31. Seems like this thing – especially at the larger scales – might be better called a “Kessler Cascade initiating anti-Satellite Weapon”.

    Reply
  32. Seems like this thing – especially at the larger scales – might be better called a Kessler Cascade initiating anti-Satellite Weapon””.”””

    Reply
  33. PS: small transcription error. If the nominal 8 × moon level illumination is achieved with a 15.4 m diameter 90% reflector, then 500,000× Moon would be exactly the above numbers, but not as I typed them. 11,500,000 m² and 3,800 m diameter.

    Reply
  34. PS: small transcription error. If the nominal 8 × moon level illumination is achieved with a 15.4 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflector then 500000× Moon would be exactly the above numbers but not as I typed them. 11500000 m² and 3800 m diameter.”

    Reply
  35. Dunno. You’re basically right of course. As is DoctorPat. Its a good start. But there are so many contrary optimizations in play. Makes it hard to pin down what really might be an optimal tactical roll-out. For instance, there is a half-a-million-to-ONE difference in producing wan street night-lighting and competently illuminating a 20 kilometer-in-diameter solar far at 0.7× to 1.5× nominal noon sunlight. ⇒ 500,000× That is a BIG difference in the size of the reflector “up there”. Like … 500,000× difference. Consider for the instance of the thing I modelled in the other article. A 90% efficient reflector in a 1,000 km altitude orbit, delivering roughly 8× nominal full-moon street lighting levels of illumination. The 10-to–15 km ‘spot’ (really a conic section of ellipsoidal projection shape) from the 1,000 km orbit required a 90% reflectance mirror of 186 m² (whate’r the shape), but if circular then 15.4 m in diameter. About 50 feet in diameter. Now, scale that 500,000× to make it a more-or-less-one-SOL illumination. Same orbit. ⇒ 15.4 × √( 500,000× ) → 11,500,000 m² AREA ⇒ √( 11,500,000 / π ) × 2 → 3,800 m Diameter Well I tell you this: a 3,800 m (2.4 mile!!!) diameter almost-perfectly-flat mirror in space is NOT going to be lofted any time soon, no matter how brilliant (ahem) the cost-effectiveness “space spider” calculations. Moreover, lest we forget, in order to get 1 Sol illumination, the “thing in the sky” is going to have to have a fixible extent (i.e. when you look up, there it is… ‘this big’) the SAME size as the sun itself. And it needs to be a focussed image of the sun. Can’t be a flat mirror. At all. So a 3,800 meter parabolically curved mirror. Thankfully it doesn’t need astronomical-observation perfection. Just “kind-of-sort-of” parabolic is OK. After all, its just for solar power (on Earth). Thankfully, the whole structure doesn’t need to slew about in order to project the Sun’s image down here on Dirt. Can’t

    Reply
  36. Dunno.You’re basically right of course. As is DoctorPat.Its a good start.But there are so many contrary optimizations in play. Makes it hard to pin down what really might be an optimal tactical roll-out. For instance there is a half-a-million-to-ONE difference in producing wan street night-lighting and competently illuminating a 20 kilometer-in-diameter solar far at 0.7× to 1.5× nominal noon sunlight. ⇒ 500000×That is a BIG difference in the size of the reflector “up there”. Like … 500000× difference.Consider for the instance of the thing I modelled in the other article. A 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} efficient reflector in a 1000 km altitude orbit delivering roughly 8× nominal full-moon street lighting levels of illumination. The 10-to–15 km ‘spot’ (really a conic section of ellipsoidal projection shape) from the 1000 km orbit required a 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectance mirror of 186 m² (whate’r the shape) but if circular then 15.4 m in diameter. About 50 feet in diameter. Now scale that 500000× to make it a more-or-less-one-SOL illumination. Same orbit. ⇒ 15.4 × √( 500000× ) → 11500000 m² AREA⇒ √( 11500000 / π ) × 2 → 3800 m DiameterWell I tell you this: a 3800 m (2.4 mile!!!) diameter almost-perfectly-flat mirror in space is NOT going to be lofted any time soon no matter how brilliant (ahem) the cost-effectiveness “space spider” calculations. Moreover lest we forget in order to get 1 Sol illumination the “thing in the sky” is going to have to have a fixible extent (i.e. when you look up there it is… ‘this big’) the SAME size as the sun itself. And it needs to be a focussed image of the sun. Can’t be a flat mirror. At all.So a 3800 meter parabolically curved mirror. Thankfully it doesn’t need astronomical-observation perfection.Just “kind-of-sort-of” parabolic is OK. After all its just

    Reply
  37. Here’s the thing…

    What does the space command center need to achieve with that projected image of the sun (PIOTS)?

    • (1) accurate tracking of the satellite relative to Sol
    • (2) accurate vectoring of mirror to ‘hit’ the target city¹ dead on.
    • (3) fairly rapid repositioning as “the next city” is queued up.
    • (4) sundry satellite maintenance: reaction fuel levels, all that.

    № 1 … Satellites stay in stabile orbits perhaps for millennia when high enough. 1,000 km up won’t cut it. Perhaps 5,000 km would do. The PIOTS would be about 45 km diameter.

    № 2 … While the PIOTS would likely be quite a bit larger than the target city, you don’t exactly want it wandering hundres of kilometers off the center of the city. Yet, there is “constant fantastic math” going on in controlling the (Sol → satellite orbit → spinning Earth → Earth seasonal inclination → target city/farm/) angles of the membrane mirror azimuth.

    Because at 5,000 km, you’ve got a minimum 45 km diameter PIOTS, having an area of 1,600 km² or 160,000 hectares. Maybe for China’s megacities this is OK.

    № 3 … Again — think about size. The 77 meter (hexagonal membrane, not triangular) diameter satellite needs to be vectored to this mutually moving system in a fashion quite different from the large-coverage GPS constellation. The vectoring changes every second. The quarter-radius of 45 km diameter (5 km) requires positioning accuracy of 0.065°. Wow.

    While this ought to be “not too hard” with the satellite gyroscopes methods, the accumulated inertial torque periodically needs to be “unspun” by jetting rocket fuel, out. Which changes the inertial moment of the bird, changing ALL calculations for how to revector it. Also, it might significantly change its orbit.
    ________________________________________

    NOW … think of a space reflector that is large enough to deliver 1.5 Sol illumination to Earth. Same 5,000 km orbit? Maybe not, 45 km PIOTS is too large but for the most ridiculously oversized solar farms. Even a 1,000 km orbit with its 9.2 km PIOTS is pretty menacing at full-Sol output.

    But consider the mirror vectoring! Oh sure, one can imagine a huge mirror (11 km across) made up of tens of thousands of little mirrors in a big truss frame, each one responsible for establishing its own angle relative to Sol, Earth an the Target Solar Farm. But the WHOLE ENCHILADA still needs to rorate too: the optimal sun-facing aspect isn’t something that the little mirrors can achieve without shadowing each other if not optimally Sol facing.

    It ought to be obvious: ain’t happening.

    Just saying,
    GoatGuy
    ________________________________________

    ¹ could be a solar farm for the much larger envisioned solar-power enhancer. Or a targeted crop region. Growing tomatoes in winter kind of thing.

    Reply
  38. Yeah, Fraas talks about 1-sol power while Chengdu-tribe talks about moonlight (through the terrible smog there). Some more moonlight is more or less useless for PV, and I have to say is useless for street lighting needs too. Full moon light is at best about 0.1 lux. Guidelines for local street lighting ranges from about 14 lux to 26 lux on pavement depending on traffic, highways are rated about 6-9 lux, “public areas in dark surroundings” requires 20-50 lux. The latter is at least 200x brighter than moonlight. Quite a big mirror, just for street lighting. Besides, ambient urban lights (like in Chengdu) easily drowns out any moonlight. As you probably also know, clear sunlight on the ground at sea level is about 10,000 lux.

    The whole “moonlight” thingy is fake news. Chengdu has a science city and building the “Tianfu New Area” a Silly Valley type city within a city (megacity, these projects are HUGE). Mostly deserted at this point (but plenty of street lights!!). I was there last winter. Now and then they “report” all these fantastic science-fictiony new developments from the project. This is one of them. The unit that announced this “initiative” is the same company that builds the J-20 stealth fighter…..’nuff said.

    Reply
  39. PS: small transcription error. If the nominal 8 × moon level illumination is achieved with a 15.4 m diameter 90% reflector, then 500,000× Moon would be exactly the above numbers, but not as I typed them. 11,500,000 m² and 3,800 m diameter.

    Reply
  40. Dunno.

    You’re basically right of course.
    As is DoctorPat.
    Its a good start.

    But there are so many contrary optimizations in play. Makes it hard to pin down what really might be an optimal tactical roll-out.

    For instance, there is a half-a-million-to-ONE difference in producing wan street night-lighting and competently illuminating a 20 kilometer-in-diameter solar far at 0.7× to 1.5× nominal noon sunlight.

    ⇒ 500,000×

    That is a BIG difference in the size of the reflector “up there”. Like … 500,000× difference.

    Consider for the instance of the thing I modelled in the other article. A 90% efficient reflector in a 1,000 km altitude orbit, delivering roughly 8× nominal full-moon street lighting levels of illumination.

    The 10-to–15 km ‘spot’ (really a conic section of ellipsoidal projection shape) from the 1,000 km orbit required a 90% reflectance mirror of 186 m² (whate’r the shape), but if circular then 15.4 m in diameter. About 50 feet in diameter.

    Now, scale that 500,000× to make it a more-or-less-one-SOL illumination. Same orbit.

    ⇒ 15.4 × √( 500,000× ) → 11,500,000 m² AREA
    ⇒ √( 11,500,000 / π ) × 2 → 3,800 m Diameter

    Well I tell you this: a 3,800 m (2.4 mile!!!) diameter almost-perfectly-flat mirror in space is NOT going to be lofted any time soon, no matter how brilliant (ahem) the cost-effectiveness “space spider” calculations.

    Moreover, lest we forget, in order to get 1 Sol illumination, the “thing in the sky” is going to have to have a fixible extent (i.e. when you look up, there it is… ‘this big’) the SAME size as the sun itself.

    And it needs to be a focussed image of the sun. Can’t be a flat mirror. At all.

    So a 3,800 meter parabolically curved mirror.
    Thankfully it doesn’t need astronomical-observation perfection.
    Just “kind-of-sort-of” parabolic is OK.

    After all, its just for solar power (on Earth).

    Thankfully, the whole structure doesn’t need to slew about in order to project the Sun’s image down here on Dirt. Can’t change the ellipse shape (at all, its impossible), but at least for a few hours, a big ellipse is just fine in coverage over most solar farms: ellipses have a minimum dimension along the MINOR axis, a dimension which NEVER changes; the only thing that does is the Major axis, or the elongation of the thing from a nominal circle. Of course the curvature of the Earth goes on to distort the ellipse further, but for most intents and purposes, “its an ellipse”.

    Hence “0.7× to 1.5×” in my specification. When it just so happens that the ellipse is circular, well … more sunlight than Sol herself provides. But most of the rest of the time, less. Less than 1.5×. Between 1.5× and some lower cutoff like 0.7×

    ‘Nuff for now.
    Just more stuff to think about.

    ••• WHAT IS THE ROLLOUT STRATEGY? •••

    Just saying,
    GoatGuy

    Reply
  41. You might like the technical side, but you may cry when you look at the economics. Basically, what you are doing is extending the operating hours of a solar PV farm. This “system” will give you an additional 2 hours, 3 at most. So a 40-50% boost in output (Fraas, the inventor, estimated a 70% boost but that is 100% optimal). That means IF the build and operating cost of the beam system is LESS than the expected boost in output (revenue), then you MAYBE are good to go. If not, it’s not worth it. All this boils down to adding the build/launch/maintenance/operating cost of the beam system into your solar PV spreadsheet. Current new large-scale commercial PV array systems are pricing in at about $23-25/MWh and estimates are $20/MWh by 2019/20. The usual project IRR for such a system is about 3.5-5%, 7% on the high side. That is LOWER than commercial WACC, ie capital destroying. That means the difference needs to be subsidized. E.g., none of the Gulf states new very large solar projects are built commercially, they are all loss-making and therefore heavily subsidized. It’s one of the things the renewable industry hates to talk about – that costs have been driven down so low that investors run away, unless tax money is deployed. Now, the inventor (Fraas) claims the “marginal” cost of the space beam will be about 10% of a solar array all-in cost, at least the cost of sending it into space, not the construction costs or other monitoring systems, eventual maintenance etc. I haven’t seen any estimates on total sun beam costs, but can imagine it’s at least 2-3x the cost of sending it into space if not more. It appears that the additional costs of the sun beam doesn’t really help the economics that much and just might be value-destroying. The other problem of course is where to beam the light. You probably want to use high-efficiency places. Too bad these places are far away from where the power is needed. The opportunity costs need to be looked at too. As of 2018, c

    Reply
  42. You might like the technical side but you may cry when you look at the economics. Basically what you are doing is extending the operating hours of a solar PV farm. This system”” will give you an additional 2 hours”” 3 at most. So a 40-50{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} boost in output (Fraas the inventor estimated a 70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} boost but that is 100{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} optimal). That means IF the build and operating cost of the beam system is LESS than the expected boost in output (revenue) then you MAYBE are good to go. If not it’s not worth it. All this boils down to adding the build/launch/maintenance/operating cost of the beam system into your solar PV spreadsheet. Current new large-scale commercial PV array systems are pricing in at about $23-25/MWh and estimates are $20/MWh by 2019/20. The usual project IRR for such a system is about 3.5-5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} 7{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} on the high side. That is LOWER than commercial WACC ie capital destroying. That means the difference needs to be subsidized. E.g. none of the Gulf states new very large solar projects are built commercially they are all loss-making and therefore heavily subsidized. It’s one of the things the renewable industry hates to talk about – that costs have been driven down so low that investors run away unless tax money is deployed. Now”” the inventor (Fraas) claims the “”””marginal”””” cost of the space beam will be about 10{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of a solar array all-in cost”” at least the cost of sending it into space not the construction costs or other monitoring systems eventual maintenance etc. I haven’t seen any estimates on total sun beam costs but can imagine it’s at least 2-3x the cost of sending it”

    Reply
  43. Unlike so many bad ideas, this is easily reversed. If the idea turns out useless or too troublesome, then just don’t launch any more and let the existing ones be deorbited. Like they never existed,

    Reply
  44. Unlike so many bad ideas this is easily reversed. If the idea turns out useless or too troublesome then just don’t launch any more and let the existing ones be deorbited. Like they never existed

    Reply
  45. I like it. This is step one towards solar power satellites. The first step being just a little ambitious from current tech, but not the huge leap required to go all the way to 1 GW power beaming.

    Reply
  46. I like it.This is step one towards solar power satellites. The first step being just a little ambitious from current tech but not the huge leap required to go all the way to 1 GW power beaming.

    Reply
  47. While orbital mirrors reflecting lasers isn’t ridiculous, that would be a completely different sort of mirror. The huge metallized film things being discussed would never have the accuracy, response time or focus to be laser weapons.

    Reply
  48. While orbital mirrors reflecting lasers isn’t ridiculous that would be a completely different sort of mirror. The huge metallized film things being discussed would never have the accuracy response time or focus to be laser weapons.

    Reply
  49. You might like the technical side, but you may cry when you look at the economics. Basically, what you are doing is extending the operating hours of a solar PV farm. This “system” will give you an additional 2 hours, 3 at most. So a 40-50% boost in output (Fraas, the inventor, estimated a 70% boost but that is 100% optimal).

    That means IF the build and operating cost of the beam system is LESS than the expected boost in output (revenue), then you MAYBE are good to go. If not, it’s not worth it. All this boils down to adding the build/launch/maintenance/operating cost of the beam system into your solar PV spreadsheet.

    Current new large-scale commercial PV array systems are pricing in at about $23-25/MWh and estimates are $20/MWh by 2019/20. The usual project IRR for such a system is about 3.5-5%, 7% on the high side. That is LOWER than commercial WACC, ie capital destroying. That means the difference needs to be subsidized. E.g., none of the Gulf states new very large solar projects are built commercially, they are all loss-making and therefore heavily subsidized. It’s one of the things the renewable industry hates to talk about – that costs have been driven down so low that investors run away, unless tax money is deployed.

    Now, the inventor (Fraas) claims the “marginal” cost of the space beam will be about 10% of a solar array all-in cost, at least the cost of sending it into space, not the construction costs or other monitoring systems, eventual maintenance etc. I haven’t seen any estimates on total sun beam costs, but can imagine it’s at least 2-3x the cost of sending it into space if not more. It appears that the additional costs of the sun beam doesn’t really help the economics that much and just might be value-destroying.

    The other problem of course is where to beam the light. You probably want to use high-efficiency places. Too bad these places are far away from where the power is needed.

    The opportunity costs need to be looked at too. As of 2018, conventional combined cycle natgas still has a LCOE lower than solar PV. And that’s without sun beam tech. And then there is the usual problem: it gets night time, eventually, and continuous base power is still a pretty nifty thing to have.

    Couldn’t really come up with other uses for sun beams than energy.

    Reply
  50. The low orbits will be problematic, because such a huge light-weight membrane will be slowed down a lot by drag in the outer extends of the atmosphere. And I wonder if the membrane could be made slightly parabolic. Then it can be smaller in higher orbits. Also, from a certain size it should be more efficient to have three satellites pulling on three corners of the membrane, instead of a central satellite and booms.

    Reply
  51. The low orbits will be problematic because such a huge light-weight membrane will be slowed down a lot by drag in the outer extends of the atmosphere.And I wonder if the membrane could be made slightly parabolic. Then it can be smaller in higher orbits. Also from a certain size it should be more efficient to have three satellites pulling on three corners of the membrane instead of a central satellite and booms.

    Reply
  52. So… what’s the operating altitude again? It matters in three senses: (1) the altitude determines the satellite’s period (sec/orbit, min/orbit, hr/orbit…) (2) in turn it determines the illuminated spot size on Earth (3) and from those, plus desired illumination, the size of the reflector № 1 in particular follows formula (P = 2π√((Re + altitude)³ / (Ge • Re²)) ) Below I assume the article’s “about 8× the intensity of full moonlight” For instance: ⇒ Altitude = 500 km (lowest reasonable altitude) ⇒ P = 5,669 sec → 94.5 min → 1.57 hr → 15.2 orbits/day ⇒ S = 4.6 km diameter ⇒ M = 8 m diameter, 90% reflectance ⇒ Altitude = 1000 km ⇒ P = 6,300 sec → 105 min → 1.75 hr → 13.7 orbits/day ⇒ S = 9.2 km diameter ⇒ M = 16 m diameter, 90% reflectance ⇒ Altitude = 2400 km ⇒ P = 8,179 sec → 136 min → 2.27 hr → 10.6 orbits/day ⇒ S = 22 km diameter ⇒ M = 38 m diameter, 90% reflectance The point is, that naturally everything has to scale with physics. (actually trigonometry) More interesting operating points: ⇒ Altitude = 8000 km … to maintain illumination for most of night ⇒ P = 17,150 sec → 286 min → 4.77 hr → 5.0 orbits/day ⇒ S = 73 km diameter ⇒ M = 125 m diameter, 90% reflectance ⇒ Altitude = 35,840 km … “geosynchronous”, never changing position in sky ⇒ P = 86,400 sec → 1,440 min → 24 hr → ⇒ S = 328 km diameter ⇒ M = 560 m diameter, 90% reflectance Then there is the idea of a “sun synchronous” orbit. I’ve been thinking about that some, and while I resist looking it up on Google (out of principle), I think that a cunning orbit would be one such that the angle of the satellite’s mirror might contrive to be at the RIGHT angle to reflect the sun exactly at the spot on Old Dirt where the artificial Moonlight x 8 is supposed to illuminate. … goat thinks … Realizes that this is possible for nearly all orbits. There is always some relative to sun-and-earth rotational rate that’d ensure the right angle. But, for all orbits including the equatorial “geostationary” on

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  53. So… what’s the operating altitude again? It matters in three senses:(1) the altitude determines the satellite’s period (sec/orbit min/orbit hr/orbit…)(2) in turn it determines the illuminated spot size on Earth(3) and from those plus desired illumination the size of the reflector№ 1 in particular follows formula (P = 2π√((Re + altitude)³ / (Ge • Re²)) )Below I assume the article’s about 8× the intensity of full moonlight””For instance:⇒ Altitude = 500 km (lowest reasonable altitude)⇒ P = 5″”669 sec → 94.5 min → 1.57 hr → 15.2 orbits/day⇒ S = 4.6 km diameter⇒ M = 8 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectance⇒ Altitude = 1000 km⇒ P = 6300 sec → 105 min → 1.75 hr → 13.7 orbits/day⇒ S = 9.2 km diameter⇒ M = 16 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectance⇒ Altitude = 2400 km⇒ P = 8179 sec → 136 min → 2.27 hr → 10.6 orbits/day⇒ S = 22 km diameter⇒ M = 38 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectanceThe point is that naturally everything has to scale with physics. (actually trigonometry) More interesting operating points: ⇒ Altitude = 8000 km … to maintain illumination for most of night⇒ P = 17150 sec → 286 min → 4.77 hr → 5.0 orbits/day⇒ S = 73 km diameter⇒ M = 125 m diameter 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectance⇒ Altitude = 35″”840 km … “”””geosynchronous”””””” never changing position in sky⇒ P = 86400 sec → 1440 min → 24 hr → ⇒ S = 328 km diameter⇒ M = 560 m diameter”” 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} reflectanceThen there is the idea of a “”””sun synchronous”””” orbit. I’ve been thinking about that some”” and while I resist looking it up on Google (out of principle) I think that a cunning orbit would be one such that the angle of the satellite’s mirror might contrive to be at”

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  54. Unlike so many bad ideas, this is easily reversed. If the idea turns out useless or too troublesome, then just don’t launch any more and let the existing ones be deorbited. Like they never existed,

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  55. I like it.

    This is step one towards solar power satellites. The first step being just a little ambitious from current tech, but not the huge leap required to go all the way to 1 GW power beaming.

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  56. While orbital mirrors reflecting lasers isn’t ridiculous, that would be a completely different sort of mirror. The huge metallized film things being discussed would never have the accuracy, response time or focus to be laser weapons.

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  57. I remember reading about something like this in 1978 or so. I think it was called SOLARES, can’t be sure since it was long ago. The idea was to put thousands of these mirror satellites into relatively closed by orbit. They would rotated to reflect light to solar power plants on earth. They could also light cities and farms. The satellites would be light and cheap but lofting the required number would be still be expensive. A mention side effect would be a permanent glimmer in the sky caused by the satellites rotating to their next target.

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  58. I remember reading about something like this in 1978 or so. I think it was called SOLARES can’t be sure since it was long ago. The idea was to put thousands of these mirror satellites into relatively closed by orbit. They would rotated to reflect light to solar power plants on earth. They could also light cities and farms. The satellites would be light and cheap but lofting the required number would be still be expensive. A mention side effect would be a permanent glimmer in the sky caused by the satellites rotating to their next target.

    Reply
  59. Oh YES, let’s ruin a beautiful night sky. And think of the pretty glow as the mirrors “set” when they leave the sun’s light. There would be the colors of pollution in the after glow.

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  60. Oh YES let’s ruin a beautiful night sky. And think of the pretty glow as the mirrors set”” when they leave the sun’s light. There would be the colors of pollution in the after glow.”””

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  61. The low orbits will be problematic, because such a huge light-weight membrane will be slowed down a lot by drag in the outer extends of the atmosphere.
    And I wonder if the membrane could be made slightly parabolic. Then it can be smaller in higher orbits. Also, from a certain size it should be more efficient to have three satellites pulling on three corners of the membrane, instead of a central satellite and booms.

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  62. So… what’s the operating altitude again? It matters in three senses:

    (1) the altitude determines the satellite’s period (sec/orbit, min/orbit, hr/orbit…)
    (2) in turn it determines the illuminated spot size on Earth
    (3) and from those, plus desired illumination, the size of the reflector

    № 1 in particular follows formula (P = 2π√((Re + altitude)³ / (Ge • Re²)) )
    Below I assume the article’s “about 8× the intensity of full moonlight”

    For instance:

    ⇒ Altitude = 500 km (lowest reasonable altitude)
    ⇒ P = 5,669 sec → 94.5 min → 1.57 hr → 15.2 orbits/day
    ⇒ S = 4.6 km diameter
    ⇒ M = 8 m diameter, 90% reflectance

    ⇒ Altitude = 1000 km
    ⇒ P = 6,300 sec → 105 min → 1.75 hr → 13.7 orbits/day
    ⇒ S = 9.2 km diameter
    ⇒ M = 16 m diameter, 90% reflectance

    ⇒ Altitude = 2400 km
    ⇒ P = 8,179 sec → 136 min → 2.27 hr → 10.6 orbits/day
    ⇒ S = 22 km diameter
    ⇒ M = 38 m diameter, 90% reflectance

    The point is, that naturally everything has to scale with physics. (actually trigonometry) More interesting operating points:
    ⇒ Altitude = 8000 km … to maintain illumination for most of night
    ⇒ P = 17,150 sec → 286 min → 4.77 hr → 5.0 orbits/day
    ⇒ S = 73 km diameter
    ⇒ M = 125 m diameter, 90% reflectance

    ⇒ Altitude = 35,840 km … “geosynchronous”, never changing position in sky
    ⇒ P = 86,400 sec → 1,440 min → 24 hr →
    ⇒ S = 328 km diameter
    ⇒ M = 560 m diameter, 90% reflectance

    Then there is the idea of a “sun synchronous” orbit. I’ve been thinking about that some, and while I resist looking it up on Google (out of principle), I think that a cunning orbit would be one such that the angle of the satellite’s mirror might contrive to be at the RIGHT angle to reflect the sun exactly at the spot on Old Dirt where the artificial Moonlight x 8 is supposed to illuminate.

    … goat thinks …

    Realizes that this is possible for nearly all orbits. There is always some relative to sun-and-earth rotational rate that’d ensure the right angle. But, for all orbits including the equatorial “geostationary” one, there’d still need to be seasonal repositioning of the reflector to deal with Earth’s orbital inclination. And our orbital obliquity. And precession. Rats…

    Oh well, it was fun.

    Just saying,
    GoatGuy

    Reply
  63. I remember reading about something like this in 1978 or so. I think it was called SOLARES, can’t be sure since it was long ago. The idea was to put thousands of these mirror satellites into relatively closed by orbit. They would rotated to reflect light to solar power plants on earth. They could also light cities and farms. The satellites would be light and cheap but lofting the required number would be still be expensive. A mention side effect would be a permanent glimmer in the sky caused by the satellites rotating to their next target.

    Reply
  64. Oh YES, let’s ruin a beautiful night sky. And think of the pretty glow as the mirrors “set” when they leave the sun’s light. There would be the colors of pollution in the after glow.

    Reply

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