Let's see....80 light years...radio and TV started in earnest in the '30's and '40's....I guess they should be packing up the old starship for a visit soon!!!
When I first saw Dyson Sphere, I thought it was a new model of this:
Not at all. That's your great depth of knowledge and wide range interests on display.
Agreed! Knowledge is power. Or that's what 'they' say at least.
I like the idea of using solar arrays to capture energy from a star; however how does the energy get back to Earth? A 93 million mile long cable? *challenge.accepted*
NASA developed a solution for that back in the 80's IMS when the idea of large orbital solar arrays was being bandied about.
The energy was to be converted into microwave energy or something like that and beamed down to a receiving station on Earth and converted to electricity. Problem was as some wags pointed out, that these arrays could easily be turned into your classic Lex Luthor Death Ray and cities could end up being cooked.
NASA developed a solution for that back in the 80's IMS when the idea of large orbital solar arrays was being bandied about.
The energy was to be converted into microwave energy or something like that and beamed down to a receiving station on Earth and converted to electricity. Problem was as some wags pointed out, that these arrays could easily be turned into your classic Lex Luthor Death Ray and cities could end up being cooked.
Of course, behind every cool invention...Someone wants to use it to kill someone else. *sigh*
NASA developed a solution for that back in the 80's IMS when the idea of large orbital solar arrays was being bandied about.
The energy was to be converted into microwave energy or something like that and beamed down to a receiving station on Earth and converted to electricity. Problem was as some wags pointed out, that these arrays could easily be turned into your classic Lex Luthor Death Ray and cities could end up being cooked.
Don't worry they couldn't get it to work as they couldn't find a loud enough "ping" to let you know when the population were done
NASA developed a solution for that back in the 80's IMS when the idea of large orbital solar arrays was being bandied about.
The energy was to be converted into microwave energy or something like that and beamed down to a receiving station on Earth and converted to electricity. Problem was as some wags pointed out, that these arrays could easily be turned into your classic Lex Luthor Death Ray and cities could end up being cooked.
Microwave death rays, while technically feasible, are not practical. The problem is the beam expands considerably from the transmitting antenna arrays. The expansion is basically dependent on the diameter of the antenna array in wavelengths.
These satellites need to be positioned from 400 to 6000 miles or so from the surface of the Earth. At these distances the physics won't allow a power density to get excessively high. The reason is defined by the "Rayleigh criterion". Here is a reasonable explanation for this: Angular resolution
Ok, this is specifically discussing telescopes, but the concept is the same for microwave transmitting antennas just in reverse.
Yeah I''m aware of microwave attenuation but if we want solar energy to be transmitted to Earth, it has to be done in some form or else it's useless. I suspect though this is why NASA stopped talking about it, it was a dead end just like the ISS is.
Yeah I''m aware of microwave attenuation but if we want solar energy to be transmitted to Earth, it has to be done in some form or else it's useless. I suspect though this is why NASA stopped talking about it, it was a dead end just like the ISS is.
Actually attenuation of the microwave power is not very high especially if the frequency is carefully chosen to not be affected by water and other molecules.
Instead of attenuation the effect on microwaves is dispersion. Dispersion is not in itself a loss just the spreading out of power. This is why the Rectennas are very large.
There have been many experiments that have shown the system losses from the Maser microwave generator to the ground based Rectenna can approach 80% efficiency.
The practical problem today is in the large solar collector in space, usually Photo Voltaic. This would need to be many hundreds of square miles in area.
As I recall, the microwave power density at the Rectenna site would be in the 1 to 5 KW/m^2 at most. Ya, you would like protection in this area but not be useful as a weapon as a Laser would be.
Besides, it would be very easy to disrupt such a space power station with a rocket with a simple chemical warhead.
ElectricAye
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When I first saw Dyson Sphere, I thought it was a new model of this:
I guess I'm showing my age... :-(
Not at all. That's your great depth of knowledge and wide range interests on display.
Agreed! Knowledge is power. Or that's what 'they' say at least.
I like the idea of using solar arrays to capture energy from a star; however how does the energy get back to Earth? A 93 million mile long cable? *challenge.accepted*
The energy was to be converted into microwave energy or something like that and beamed down to a receiving station on Earth and converted to electricity. Problem was as some wags pointed out, that these arrays could easily be turned into your classic Lex Luthor Death Ray and cities could end up being cooked.
Of course, behind every cool invention...Someone wants to use it to kill someone else. *sigh*
Don't worry they couldn't get it to work as they couldn't find a loud enough "ping" to let you know when the population were done
These satellites need to be positioned from 400 to 6000 miles or so from the surface of the Earth. At these distances the physics won't allow a power density to get excessively high. The reason is defined by the "Rayleigh criterion". Here is a reasonable explanation for this:
Angular resolution
Ok, this is specifically discussing telescopes, but the concept is the same for microwave transmitting antennas just in reverse.
Duane J
Instead of attenuation the effect on microwaves is dispersion. Dispersion is not in itself a loss just the spreading out of power. This is why the Rectennas are very large.
There have been many experiments that have shown the system losses from the Maser microwave generator to the ground based Rectenna can approach 80% efficiency.
The practical problem today is in the large solar collector in space, usually Photo Voltaic. This would need to be many hundreds of square miles in area.
As I recall, the microwave power density at the Rectenna site would be in the 1 to 5 KW/m^2 at most. Ya, you would like protection in this area but not be useful as a weapon as a Laser would be.
Besides, it would be very easy to disrupt such a space power station with a rocket with a simple chemical warhead.
Duane J