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#51
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins****ting Her Diapers!)
No, it doesn't need to be--that's only one potential architecture. The benefit of GEO is that you can get continuous service from a single satellite, whereas lower altitudes require a constellation of them. However, the latter would be easier to demonstrate with a part-time system, which would be a proof of concept for the whole constellation. Powersats in LEO to me doesn't seem to be much better than just building the thing on the ground. At night, a powersat visible from the ground will probably also be in the Earth's shadow. So why bother putting it in orbit? Getting something that big in orbit is way too expensive anyway, and if the thing is built on the ground, you can skip the conversion of the power to microwaves, and skip the rectennas. That would cut losses by something like 40% or more. And doing repairs and so on would be way easier with it on the ground. Of course it would only generate power during the daytime, but that's when electricity usage peaks anyway. And of course we'll need other power plants at night, but we'd want multiple methods of power generation anyway. Windmills, nukes, and so on. |
#52
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins ****ting Her Diapers!)
On Tue, 05 Jun 2007 19:47:18 GMT, in a place far, far away, robert
casey made the phosphor on my monitor glow in such a way as to indicate that: No, it doesn't need to be--that's only one potential architecture. The benefit of GEO is that you can get continuous service from a single satellite, whereas lower altitudes require a constellation of them. However, the latter would be easier to demonstrate with a part-time system, which would be a proof of concept for the whole constellation. Powersats in LEO to me doesn't seem to be much better than just building the thing on the ground. I didn't say LEO. Just an orbit much closer to earth to reduce the size of the transmitting antenna. Satellites that are eclipsed would be supplemented by others from the constellation, with split beams. |
#53
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins ****ting Her Diapers!)
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#54
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins****ting Her Diapers!)
Re : Space Solar Panels replacing petrol in cars.
People forget that in the USA, a signififant percentage of electricity is produced with polluting coal. This is a major source of pollution for the planet. So if you can get alternative sources of electricity, it will alleviate this very nasty source of pollution. It may not fir the car problem, it helps fix another problem. |
#55
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins ****ting Her Diapers!)
On Jun 5, 10:47 pm, robert casey wrote:
No, it doesn't need to be--that's only one potential architecture. The benefit of GEO is that you can get continuous service from a single satellite, whereas lower altitudes require a constellation of them. However, the latter would be easier to demonstrate with a part-time system, which would be a proof of concept for the whole constellation. Powersats in LEO to me doesn't seem to be much better than just building the thing on the ground. At night, a powersat visible from the ground will probably also be in the Earth's shadow. In shadow only twice a year during equinoxes, and only for an hour or so per day. So why bother putting it in orbit? Getting something that big in orbit is way too expensive anyway, and if the thing is built on the ground, you can skip the conversion of the power to microwaves, and skip the rectennas. That would cut losses by something like 40% or more. And doing repairs and so on would be way easier with it on the ground. Of course it would only generate power during the daytime, but that's when electricity usage peaks anyway. And of course we'll need other power plants at night, but we'd want multiple methods of power generation anyway. Windmills, nukes, and so on. Envisioned power loss (due to atm.) about 5%. Advantages: 1. roughly double efficiency - no atm.; 2. +30% approx. depends on location of equivalent Earth based array - no weather; 3. double that again for 24/7 operation - no night life :-)) Disadvantage: requires *really* cheap launches. IIRC, $100/kg would just about do it, for Moon produced arrays. IMHO, nukes are the only reasonable way to cut CO2. They would replace the worst source of pollution - coal. Incidentally, nukes would also *diminish* radioactive waste released into the atm. FYI http://www.ornl.gov/info/ornlreview/...t/colmain.html |
#56
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins ****ting Her Diapers!)
In article k.net,
robert casey wrote: Powersats in LEO to me doesn't seem to be much better than just building the thing on the ground. That's OK; this is no doubt just because you haven't looked into them very deeply. At night, a powersat visible from the ground will probably also be in the Earth's shadow. Incorrect. A satellite in GEO is in sunlight 24 hours a day, except for a brief eclipse for about 20 minutes (IIRC) twice a year. and if the thing is built on the ground, you can skip the conversion of the power to microwaves, and skip the rectennas. That would cut losses by something like 40% or more. Wrong again. Conversion to microwaves and back is extremely efficient -- around 90% is reasonable to expect. Of course it would only generate power during the daytime, but that's when electricity usage peaks anyway. We need to serve baseline power, not just peak power. And as Henry points out, the daytime peaks may well smooth out as we start substituting other energy sources for transportation. (Cars will be charged and synthetic fuels will be generated whenever power is cheapest.) Best, - Joe |
#57
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins ****ting Her Diapers!)
In article .com,
Hyper wrote: IMHO, nukes are the only reasonable way to cut CO2. They would replace the worst source of pollution - coal. Incidentally, nukes would also *diminish* radioactive waste released into the atm. FYI http://www.ornl.gov/info/ornlreview/...t/colmain.html Unless, of course, Bussard's approach to fusion can be made to work. It certainly looks promising from the preliminary data -- it's appalling that it's not getting a drop of funding. http://www.strout.net/info/science/polywell/ (Incidentally, I've donated $50 to this research; if you see any merit in it, I encourage you to donate whatever you can as well. Waiting for government or angels to step in doesn't seem to be working.) Best, - Joe |
#58
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins ****ting Her Diapers!)
:: Powersats in LEO to me doesn't seem to be much better than just
:: building the thing on the ground. At night, a powersat visible from :: the ground will probably also be in the Earth's shadow. : Joe Strout : Incorrect. A satellite in GEO is in sunlight 24 hours a day, except : for a brief eclipse for about 20 minutes (IIRC) twice a year. OK, but how does what happens to a satellite in GEO make that claim about LEO incorrect? Mind you, nobody was proposing a LEO SPS upthread, but if anybody had, I'd agree there are quite a few problems with the notion. Wayne Throop http://sheol.org/throopw |
#59
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins ****ting Her Diapers!)
In article ,
Joe Strout wrote: In article k.net, robert casey wrote: Powersats in LEO to me doesn't seem to be much better than just building the thing on the ground. That's OK; this is no doubt just because you haven't looked into them very deeply. At night, a powersat visible from the ground will probably also be in the Earth's shadow. Oops -- sorry, you said LEO, and my brain read it as GEO. You're right, a LEO powersat doesn't make too much sense, though one in a somewhat higher (even if below GEO) satellite might. That's one of those continuous engineering trade-offs, that would require running some real numbers (and detailed other assumptions) to find an optimum. Best, - Joe |
#60
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Bush and VSE (was Breaking News! NASA Astronaut Marsha Ivins ****ting Her Diapers!)
On Tue, 05 Jun 2007 14:32:08 -0700, in a place far, far away, Hyper
made the phosphor on my monitor glow in such a way as to indicate that: On Jun 5, 10:47 pm, robert casey wrote: No, it doesn't need to be--that's only one potential architecture. The benefit of GEO is that you can get continuous service from a single satellite, whereas lower altitudes require a constellation of them. However, the latter would be easier to demonstrate with a part-time system, which would be a proof of concept for the whole constellation. Powersats in LEO to me doesn't seem to be much better than just building the thing on the ground. At night, a powersat visible from the ground will probably also be in the Earth's shadow. In shadow only twice a year during equinoxes, and only for an hour or so per day. That's the case only for GEO. We were talking about LEO. |
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