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Close Sun-orbiting mirrors for beamed propulsion and space solar power.
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#22
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Close Sun-orbiting mirrors for beamed propulsion and space solar power.
wrote in message
... ================================================== =========== On Wednesday, June 21, 2017 at 9:10:29 AM UTC-4, Robert Clark wrote: Look at it in terms of how much needs to be radiated per unit area. This research project expects to reflect 99.9% of the light energy away: April 6, 2017 Solar Surfing Robert Youngquist NASA Kennedy Space Center Quote:
Seems like a pipe dream to me. We pay decent money for mirrors with ~99.7% reflectance over some limited wavelength range. George H. --- ================================================== ======= A reflectivity of 99.7% is probably good enough for the purpose. But this new research is to make it over the entire optical and infrared range. For the existing materials with high reflectivity over limited wavelengths I wonder if it would be possible to stack them to get the high reflectivity over a larger wavelength range. Also, instead of a high reflectivity mirror could we use a ultra low absorption lens? Bob Clark ---------------------------------------------------------------------------------------------------------------------------------- Finally, nanotechnology can now fulfill its potential to revolutionize 21st-century technology, from the space elevator, to private, orbital launchers, to 'flying cars'. This crowdfunding campaign is to prove it: Nanotech: from air to space. https://www.indiegogo.com/projects/n...ce/x/13319568/ ---------------------------------------------------------------------------------------------------------------------------------- |
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Close Sun-orbiting mirrors for beamed propulsion and space solarpower.
Robert Clark wrote:
A reflectivity of 99.7% is probably good enough for the purpose. But this new research is to make it over the entire optical and infrared range. For the existing materials with high reflectivity over limited wavelengths I wonder if it would be possible to stack them to get the high reflectivity over a larger wavelength range. Also, instead of a high reflectivity mirror could we use a ultra low absorption lens? Sundiver, anyone? Jeff |
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Close Sun-orbiting mirrors for beamed propulsion and space solar power.
On Friday, June 23, 2017 at 12:55:31 PM UTC-4, Fred J. McCall wrote:
wrote: I was thinking about beamed energy for Earth to-orbit power. Well, you should stop thinking about it. You will only, as is your wont, reinvent it badly with sketchy science. snip said reinvention If it is reinvention that is ok. Getting products on my own makes me feel close to the cutting edge. A duplicate means comparative applied intelligence has occurred. The relations given are exact field not sketchy. Beaming lasers into the rear-end of an MHD motor does not sound common place. For what it is worth, an MHD uses the magnetic field of an ion to repel. So positive ions travel in the same direction as the negative particles. It is rather trivial to test. I can offer to make one for time and materials. A 1 kw uv laser and a 1kW visible laser and a cavity held in suspension. I..E. a cavity on a balance scale. I would also add a superconducting MHD coil/magnet. Making the solar cells the only hard part. A microwave power magnet might also be checked. I would need help if the microwave option is desired. Believe it or not I did a test of the Sawyer? EM Drive. It came in less than an once at 1.5Kw. Except I checked using a traveling wave waveguide. |
#26
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Close Sun-orbiting mirrors for beamed propulsion and space solar power.
It means no such thing. What it means is: 1) You're trying to 'invent' in a field that you haven't a clue about the current state of the art of, and 2) Because you usually come up with some really technically ****ed up way to try to do something we already know how to do if we want to, you just waste everyone's time. I said I feel good about my invention regardless of its first discovery status. The MHD motor is the true genius. My invention is technically an abstract "fountain" of fuel ions. Focusing on the motor chamber with multiple lasers is viable also. It would also be possible to carry fuel along also. The fuel could be something like hydrazine for a hybrid fountain motor. The chamber can be a burning normal rocket motor. This would allow boosting at higher altitudes. If the fuel was like Freon, the laser would have to do ALL the plasma making. The allowed flight path, other than straight up exists I believe. An asymmetric ion emission could give an orbital velocity. In fact a second motor could be added where the side of the rocket has an open view port. Giving a change 90 degrees to full orbital acceleration. But this must occur in the atmosphere. Thereby defining the usefulness. Can it accelerate to orbital velocity by 100K feet of altitude? This basically only defines a minimal power level. |
#27
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Close Sun-orbiting mirrors for beamed propulsion and space solar power.
"Robert Clark" wrote in message news
================================================== ================
================================================== ================ " wrote in message ... ================================================== ================ On Tuesday, June 20, 2017 at 10:31:48 AM UTC-7, Robert Clark wrote: At a solar radius of 700,000 km away from the Sun, based on the light intensity going inversely by the square of the distance, and with 1,360 watts per sq. meter (in space) at the Earth’s distance, or 1.36 gigawatts per sq. km., I estimate this should give 60 terawatts per sq. km. at only a solar radius away from the Sun. But in the post above, I had estimated that fully *on* the Sun’s surface we could collect 60 terawatts per sq. km. of power. Anyone have an explanation of this discrepancy? I'm not going to go through the math for you, but think about how much of the Sun your hypothetical power-collector can "see" from a radius away as opposed to "on the surface" (which I take to mean just above the photosphere). ... Mark L. Fergerson --- ================================================== ================= The suggestion that close in to the surface at a solar radius away this will limit the amount of the Sun's surface it can see is a good one. But if this was the issue we would expect the solar radiance would be reduced even further below what was available directly on the surface, not equal to it. --- ================================================== =============== ================================================== =============== OK. I think I understand your argument now: From the Earth's distance the lightrays are nearly parallel and you receive the light from the entire solar disk. But when you make a comparison to a much closer distance by just increasing the solar radiance according to the closer distance you are *assuming* the illumination will be to the same extent at that distance. In actuality though, a significant portion of the solar disk will not be observable. See the image he https://ibb.co/hionF5 That angle at center calculates to be 60° because its cosine is r/2r = 1/2. So you see only 60°/90° = 2/3rds of the solar disk will be observable at that distance. I might estimate the radiance at that distance then as 40 terawatts instead of 60 terawatts. However, because not all the rays are parallel at this distance I'm not sure all portions of the Sun would make the same contribution to the total so the answer might not be proportional. Perhaps someone can calculate this. Bob Clark ---------------------------------------------------------------------------------------------------------------------------------- Finally, nanotechnology can now fulfill its potential to revolutionize 21st-century technology, from the space elevator, to private, orbital launchers, to 'flying cars'. This crowdfunding campaign is to prove it: Nanotech: from air to space. https://www.indiegogo.com/projects/n...ce/x/13319568/ ---------------------------------------------------------------------------------------------------------------------------------- |
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Close Sun-orbiting mirrors for beamed propulsion and space solar power.
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#29
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Close Sun-orbiting mirrors for beamed propulsion and space solar power.
"Robert Clark" wrote in message news
================================================= ====================== At the distance of the Parker probe, a 1 km sq. mirror could collect a terawatt of power for beamed propulsion or space solar power beamed to Earth. But could we put the mirror actually on the surface of the Sun? The Sun puts out 3.86X10^26 watts of power, http://m.wolframalpha.com/input/?i=s...nosity&x=0&y=0. Given its 700,000 km radius, this amounts to over 60 terawatts per sq. km. This is 3 times the total energy usage of humans on Earth from all sources. Could we have a station on the Sun’s surface that would persist long term? The Sun’s surface is at about 5,500 C. The highest temperature ceramic we have is at about 4,000 C: Rediscovered ceramic Hafnium Carbide can withstand temperatures three times hotter than lava at 4050 celsius and could help enable hypersonic planes. brian wang | September 17, 2014 https://www.nextbigfuture.com/2014/0...m-carbine.html However, there are cases such as with rocket engine combustion chambers where the operating temperature is well above the melting point of the material composing the engine. The reason this is possible is that in order for a material to undergo a phase change from solid to liquid not only does it have to be at the melting point but a sufficient quantity of heat known as the heat of fusion has to be supplied to it. So with high performance rocket engines such as the SSME’s a cooling techniques known as regenerative cooling is used that circulates cool fuel around the engine to draw off adequate heat to prevent melting from occurring. However, with rocket engines this cooling fuel is burned or dispensed with after being used for the cooling. So this wouldn’t work for a power station existing long term on the surface of the Sun. You would need something like a refrigeration system. The Parker probe will use a refrigeration system to lower the temperature of the components of the spacecraft from 1,400 C to room temperature. This is about the same temperature drop as the temperature drop from the Sun’s surface to the maximum temperature of our high temperature ceramics. So it should be possible to do this temperature drop on the surface of the Sun using our highest temperature ceramics. Still, we might not want the extra difficulty of landing on the Sun. If we make the distance to the Sun of our beaming station about 1/3rd that of the Parker probe we would be at 10 terawatts per sq. km. Two of these would provide the entire energy requirements for the entire human population, and the surrounding temperatures wouldn’t be so extreme. Bob Clark --- ================================================= ==================== Just saw this mentioned in the comments to an article on the Parker Solar Probe on Centauri-dreams.org: April 6, 2017 Solar Surfing Robert Youngquist NASA Kennedy Space Center Quote:
At a solar radius of 700,000 km away from the Sun, based on the light intensity going inversely by the square of the distance, and with 1,360 watts per sq. meter (in space) at the Earth’s distance, or 1.36 gigawatts per sq. km., I estimate this should give 60 terawatts per sq. km. at only a solar radius away from the Sun. But in the post above, I had estimated that fully *on* the Sun’s surface we could collect 60 terawatts per sq. km. of power. Anyone have an explanation of this discrepancy? In any case if this research team succeeds in producing this ultra high reflective, high temperature material, then a mirror smaller than a kilometer across a solar radius away from the Sun could collect enough energy for the total energy usage for the entire human population of the Earth. Also, interesting is 16 solar collectors a kilometer across could provide a petawatt of power. But these are power levels long about dreamed in science fiction for doing beamed propulsion of large-scale, *manned* spacecraft on relativistic, interstellar flights. Bob Clark ---------------------------------------------------------------------------------------------------------------------------------- Finally, nanotechnology can now fulfill its potential to revolutionize 21st-century technology, from the space elevator, to private, orbital launchers, to 'flying cars'. This crowdfunding campaign is to prove it: Nanotech: from air to space. https://www.indiegogo.com/projects/n...ce/x/13319568/ ---------------------------------------------------------------------------------------------------------------------------------- Ok. I looked up the method of calculating the solar radiance per unit area according to distance. For the Earth's distance away from the Sun, it's calculated by taking the total radiance of the Sun and dividing that by the total surface area of a sphere at the Earth's distance away. The total solar radiance is 3.86X10^26 watts. The distance of the Earth away is 150,000,000,000 meters. So the solar radiance per square meter at the Earth's distance is 3.86x10^26/(4*Pi*150,000,000,000^2) = 1,365 watts per sq. meter, matching the cited amount. So for the proposed solar probe only 700,000 km away from the solar surface, this is for a sphere of radius 1,400,000 km. And the solar radiance per square kilometer there is: 3.86x10^26/(4*Pi*1,400,000^2) = 15.7 terawatts per square km. This is close to the entire energy usage from all sources for the entire human population of Earth. Bob Clark -- |
#30
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Close Sun-orbiting mirrors for beamed propulsion and space solar power.
"Robert Clark" wrote in message news
================================================= ====================== At the distance of the Parker probe, a 1 km sq. mirror could collect a terawatt of power for beamed propulsion or space solar power beamed to Earth. But could we put the mirror actually on the surface of the Sun? The Sun puts out 3.86X10^26 watts of power, http://m.wolframalpha.com/input/?i=s...nosity&x=0&y=0. Given its 700,000 km radius, this amounts to over 60 terawatts per sq. km. This is 3 times the total energy usage of humans on Earth from all sources. Could we have a station on the Sun’s surface that would persist long term? The Sun’s surface is at about 5,500 C. The highest temperature ceramic we have is at about 4,000 C: Rediscovered ceramic Hafnium Carbide can withstand temperatures three times hotter than lava at 4050 celsius and could help enable hypersonic planes. brian wang | September 17, 2014 https://www.nextbigfuture.com/2014/0...m-carbine.html However, there are cases such as with rocket engine combustion chambers where the operating temperature is well above the melting point of the material composing the engine. The reason this is possible is that in order for a material to undergo a phase change from solid to liquid not only does it have to be at the melting point but a sufficient quantity of heat known as the heat of fusion has to be supplied to it. So with high performance rocket engines such as the SSME’s a cooling techniques known as regenerative cooling is used that circulates cool fuel around the engine to draw off adequate heat to prevent melting from occurring. However, with rocket engines this cooling fuel is burned or dispensed with after being used for the cooling. So this wouldn’t work for a power station existing long term on the surface of the Sun. You would need something like a refrigeration system. The Parker probe will use a refrigeration system to lower the temperature of the components of the spacecraft from 1,400 C to room temperature. This is about the same temperature drop as the temperature drop from the Sun’s surface to the maximum temperature of our high temperature ceramics. So it should be possible to do this temperature drop on the surface of the Sun using our highest temperature ceramics. Still, we might not want the extra difficulty of landing on the Sun. If we make the distance to the Sun of our beaming station about 1/3rd that of the Parker probe we would be at 10 terawatts per sq. km. Two of these would provide the entire energy requirements for the entire human population, and the surrounding temperatures wouldn’t be so extreme. --- ================================================= ==================== Just saw this mentioned in the comments to an article on the Parker Solar Probe on Centauri-dreams.org: April 6, 2017 Solar Surfing Robert Youngquist NASA Kennedy Space Center Quote:
At a solar radius of 700,000 km away from the Sun, based on the light intensity going inversely by the square of the distance, and with 1,360 watts per sq. meter (in space) at the Earth’s distance, or 1.36 gigawatts per sq. km., I estimate this should give 60 terawatts per sq. km. at only a solar radius away from the Sun. But in the post above, I had estimated that fully *on* the Sun’s surface we could collect 60 terawatts per sq. km. of power. Anyone have an explanation of this discrepancy? In any case if this research team succeeds in producing this ultra high reflective, high temperature material, then a mirror smaller than a kilometer across a solar radius away from the Sun could collect enough energy for the total energy usage for the entire human population of the Earth. Also, interesting is 16 solar collectors a kilometer across could provide a petawatt of power. But these are power levels long about dreamed in science fiction for doing beamed propulsion of large-scale, *manned* spacecraft on relativistic, interstellar flights. ---------------------------------------------------------------------------------------------------------------------------------- Finally, nanotechnology can now fulfill its potential to revolutionize 21st-century technology, from the space elevator, to private, orbital launchers, to 'flying cars'. This crowdfunding campaign is to prove it: Nanotech: from air to space. https://www.indiegogo.com/projects/n...ce/x/13319568/ ---------------------------------------------------------------------------------------------------------------------------------- --- It has been theorized planetary-scale lasers might be detectable at galactic distances: http://www.popularmechanics.com/spac...-space-travel/ I wonder if the effects of lightsail propulsion through the interstellar medium might be detectable in our own galaxy. A kilometer scale lightsail moving at relativistic speeds should accelerate the interstellar plasma. This should generate EM waves that might be detectable by us. This EM radiation being detected away from a star system may make it identifiable. Bob Clark -- |
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