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Here's an article from the Department of Energy that outlines a few options: https://www.energy.gov/articles/space-based-solar-power https://www.energy.gov/arti

by isaacg 6y ago

Here's an article from the Department of Energy that outlines a few options: https://www.energy.gov/articles/space-based-solar-power https://www.energy.gov/articles/space-based-solar-power Microwaves and lasers are the two options they describe.

willis936 6y ago
That's a lot of cooked goose. In all seriousness, that is a pretty terrifying industrial project. I'm not sure how you'd make the failsafes strong enough to match the risk of cooking thousands of people alive.
- gameman144 6y ago
  Moreover, how to keep that from being intentionally weaponized, assuming that it is strong enough to cook people alive.
  - Terr_ 6y ago
    I imagine a large solar power-sat in orbit could be easily crippled by missiles launched from outside its aim-zone, or even well-aimed orbital debris being slung around. I'd worry more about such an installation being hacked/sabotaged by someone who doesn't care if the billions-of-dollars investment gets turned into confetti within a few hours.
    - willis936 6y ago
      This is why software is kept out of control systems whenever possible. “They hacked the web interface that tells me how much power the diagnostic thinks is being generated so now it doesn’t agree with the receiver” isn’t as scary as “they redirected the death ray to a nearby city”.
- isaacg 6y ago
  That's why the microwaves approach might be preferable to the laser approach: "Safe, low intensity levels hardly stronger than the midday sun. Birds and planes wouldn’t notice much of anything flying across their paths."
- DennisP 6y ago
  The power density wouldn't be near that bad. From geostationary, the footprint would be several square miles, and birds could fly through the beam without harm. Even getting that much focus from phased-array transmitters would require a reference signal from the ground, so if the beam went astray it would spread out much more. Despite the low power density the ground station would still be cheap, since it'd mostly be wire antenna. (Source: the book The Case for Space Solar Power)
- elihu 6y ago
  > The long wavelength of the microwave requires a long antenna, and allows power to be beamed through the Earth’s atmosphere, rain or shine, at safe, low intensity levels hardly stronger than the midday sun. Birds and planes wouldn’t notice much of anything flying across their paths. It doesn't look like they mention a specific wavelength in the article, but the reference to "long wavelength" and "long antenna" seems to imply frequencies much lower than what I'd consider microwave. Generally, the lower the frequency is, the less harm it causes to living things. Though I either way I wouldn't want to live right next to the ground station. I suppose it would be similar to living right next to a radio transmission tower or a radar station.
  - willis936 6y ago
    I generally expect sub 100 MHz to be called radio rather than microwave, but I shouldn’t make assumptions. So you need a quarter wave to be longer than a building to make it not a concern, practically it needs to be much longer if you’re sending serious power and want to keep the density down. Let’s aim for a 1 km long antenna in space with voltage high enough that ohmic losses are not a concern, or a very large superconducting antenna and all of the apparatus that goes with it. Millions of volts likes to arc when you have debris just floating around everywhere in space. Superconducting is much more attractive regardless of the extra apparatus. I don’t see many points of concern, though you could still damage infrastructure if you aren’t constantly aligned. Blowing up terrestrial grids isn’t as bad as cooking people alive. It would still be the most dangerous thing we've ever put in space by a pretty wide margin. Keep space filled exclusively with small tin cans is not an accident and not entirely due to technical or economic limitations. It is a very sensitive political area. Putting anything that could be dangerous in orbit makes it dangerous to everyone. So your adversary across the ocean blows up a reactor? Cool. As long as they don't blow me up.
    - elihu 6y ago
      > It would still be the most dangerous thing we've ever put in space by a pretty wide margin. I don't know about that. We set off a 1.4 megaton nuclear warhead in space back in 1962 just to see what would happen. (What happened is that we created a temporary radiation belt, knocked out a bunch of satellites, damaged some of the electrical and communication infrastructure in Hawaii, and caused some impressive light shows.) https://en.wikipedia.org/wiki/Starfish_Prime https://en.wikipedia.org/wiki/Starfish_Prime
- baybal2 6y ago
  Or you can microwave cities. Pump few gigawatts of microwaves over a country, and revert it to stone age in minutes.

by isaacg 6y ago

willis936 6y ago

That's a lot of cooked goose. In all seriousness, that is a pretty terrifying industrial project. I'm not sure how you'd make the failsafes strong enough to match the risk of cooking thousands of people alive.

gameman144 6y ago
Moreover, how to keep that from being intentionally weaponized, assuming that it is strong enough to cook people alive.
- Terr_ 6y ago
  I imagine a large solar power-sat in orbit could be easily crippled by missiles launched from outside its aim-zone, or even well-aimed orbital debris being slung around. I'd worry more about such an installation being hacked/sabotaged by someone who doesn't care if the billions-of-dollars investment gets turned into confetti within a few hours.
  - willis936 6y ago
    This is why software is kept out of control systems whenever possible. “They hacked the web interface that tells me how much power the diagnostic thinks is being generated so now it doesn’t agree with the receiver” isn’t as scary as “they redirected the death ray to a nearby city”.
isaacg 6y ago
That's why the microwaves approach might be preferable to the laser approach: "Safe, low intensity levels hardly stronger than the midday sun. Birds and planes wouldn’t notice much of anything flying across their paths."
DennisP 6y ago
The power density wouldn't be near that bad. From geostationary, the footprint would be several square miles, and birds could fly through the beam without harm. Even getting that much focus from phased-array transmitters would require a reference signal from the ground, so if the beam went astray it would spread out much more. Despite the low power density the ground station would still be cheap, since it'd mostly be wire antenna. (Source: the book The Case for Space Solar Power)
elihu 6y ago
> The long wavelength of the microwave requires a long antenna, and allows power to be beamed through the Earth’s atmosphere, rain or shine, at safe, low intensity levels hardly stronger than the midday sun. Birds and planes wouldn’t notice much of anything flying across their paths. It doesn't look like they mention a specific wavelength in the article, but the reference to "long wavelength" and "long antenna" seems to imply frequencies much lower than what I'd consider microwave. Generally, the lower the frequency is, the less harm it causes to living things. Though I either way I wouldn't want to live right next to the ground station. I suppose it would be similar to living right next to a radio transmission tower or a radar station.
- willis936 6y ago
  I generally expect sub 100 MHz to be called radio rather than microwave, but I shouldn’t make assumptions. So you need a quarter wave to be longer than a building to make it not a concern, practically it needs to be much longer if you’re sending serious power and want to keep the density down. Let’s aim for a 1 km long antenna in space with voltage high enough that ohmic losses are not a concern, or a very large superconducting antenna and all of the apparatus that goes with it. Millions of volts likes to arc when you have debris just floating around everywhere in space. Superconducting is much more attractive regardless of the extra apparatus. I don’t see many points of concern, though you could still damage infrastructure if you aren’t constantly aligned. Blowing up terrestrial grids isn’t as bad as cooking people alive. It would still be the most dangerous thing we've ever put in space by a pretty wide margin. Keep space filled exclusively with small tin cans is not an accident and not entirely due to technical or economic limitations. It is a very sensitive political area. Putting anything that could be dangerous in orbit makes it dangerous to everyone. So your adversary across the ocean blows up a reactor? Cool. As long as they don't blow me up.
  - elihu 6y ago
    > It would still be the most dangerous thing we've ever put in space by a pretty wide margin. I don't know about that. We set off a 1.4 megaton nuclear warhead in space back in 1962 just to see what would happen. (What happened is that we created a temporary radiation belt, knocked out a bunch of satellites, damaged some of the electrical and communication infrastructure in Hawaii, and caused some impressive light shows.) https://en.wikipedia.org/wiki/Starfish_Prime https://en.wikipedia.org/wiki/Starfish_Prime
baybal2 6y ago
Or you can microwave cities. Pump few gigawatts of microwaves over a country, and revert it to stone age in minutes.