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Another ignorant question ... so you have a massively powerful microwave beam pointed at a certain spot of your nation. What happens when it misses? Passes over

Another ignorant question ... so you have a massively powerful microwave beam pointed at a certain spot of your nation. What happens when it misses? Passes over the inhabited land that's infinitesimal fractions of a degree away from the target? From 36000 miles, a few miles is a rounding error. Must take some huge tolerances to keep the beam pointed in the right place. Is this even dangerous, or am I off base? I know they're nervous about nuclear since Fukishima, but unless I'm mistaken there's similar risks with this option.

trhway 13y ago
and a movie about villains hacking in and taking control of the beam. Steven Seagal has similar one ...
puls 13y ago
I can't believe nobody has mentioned this yet: exactly this was one of the standard disasters in SimCity 2000, where "microwave" was one of the power plant types.
- deleted 13y ago
  [deleted]
- HCIdivision17 13y ago
  Thanks for saving me the trouble. Microwave tech was awesome and cost effective until the first time the satellite got out of alignment and burned half the city down. I've been terrified of the idea ever since: you just can't make a weapon like that fail safe, and if you do manage, then your throughput is too low to make it worth it.
  - worldsayshi 13y ago
    What you possibly could do is to not have a single emitter but loads of them for each collector. So that a single satellite getting out of alignment would be harmless. Many emitters would need to get out of alignment pushing the beam in the same direction for it to be harmful.
XaspR8d 13y ago
Total nostalgia anecdote here, but Sim City 2000 had that as a disaster. I believe it was a constant risk whenever you built orbital-solar-to-microwave plants.
lutusp 13y ago
> Is this even dangerous, or am I off base? I know they're nervous about nuclear since Fukishima, but unless I'm mistaken there's similar risks with this option. No, not true. Don't confuse ionizing radiation as from Fukushima, with non-ionizing radiation, as from microwaves. They're very different. Microwave radiation isn't nearly as dangerous -- it can't break cellular bonds like ionizing radiation can, it can only heat things up. A microwave power system would have to pass strict safety tests, to make sure the microwave radiation level at the surface (near occupied areas) is well below that from the other big electromagnetic emitter -- the sun. That should be an easy standard to meet.
- finnh 13y ago
  The danger isn't from "overflow" radiation when the microwave beam is on target. The danger is when the microwave is off-target by a couple hundred feet (teensy fractions of a degree, considering the distances involved) and suddenly your concentrated 1GW beam is pointing at an apartment building. That beam is WAY more powerful than the sun per unit area. If not, we'd just use the sun.
  - skorgu 13y ago
    > That beam is WAY more powerful than the sun per unit area. If not, we'd just use the sun. Not necessarily. Rectennas can get ~80% conversion efficiency, PV panels you can actually get in bulk are closer to 30. So you can have a beam about as strong as the sun and get ~triple the power out the other end by using microwaves instead of light.
    - danielweber 13y ago
      When you express what SPS is doing as "making solar 3 times more land-efficient" it looks kind of crazy. Maybe dump the billions of dollars that would be needed for launching just one of these into squeezing another percentage point out of all new solar cells.
  - worldsayshi 13y ago
    Just use multiple source satellites for each destination collector. Each being harmless, together they are powerful enough for a decent output.
Someone 13y ago
Read the article. It's not massively powerful; the beam will deliver about a kW per square meter (that's a GW per square kilometer).
- scott_karana 13y ago
  So... it's as powerful as an unshielded microwave oven. Imagine the hideous health implications if a city block got cooked.
  - spiritplumber 13y ago
    Rather than imagining it, play Sim City 2000 and see for yourself!
  - e12e 13y ago
    Is it? Most (old) ovens used to be rated at 1KW, but they certainly weren't 1 square meter, more like half a square foot. You can fit quite a few half-square "feet" in a square meter (roughly 3*6 -- so 1kw/sqm would be about 1/18 of a microwave oven?).
    - scott_karana 13y ago
      True, thanks for correcting my math. I still think there could be negative health effects, but obviously they wouldn't be as pronounced. :)
Florin_Andrei 13y ago
This is probably the one thing that makes me act like a luddite - smash the darn thing before it gets a chance to even twitch a little.
danielweber 13y ago
In fact, the beam wouldn’t even be intense enough to heat your coffee. In the center of the beam in a commercial SPS system, the power density would be 1 kilowatt per square meter, which is about equal to the intensity of sunlight Of course, if it's only as intense as sunlight, you would wonder why they are bothering building a rectenna and an SPS. . .
InclinedPlane 13y ago
The trick is you don't let the microwave beam get very strong. If you keep it at a fraction of solar power (say, a few hundred watts per m^2) then it won't be that dangerous. And yet because it's RF energy instead of solar energy and consistently at the same power 24/7 it's much, much easier to build the ground based infrastructure to collect and use the power. Also, it's pretty easy to keep the beam away from populated areas.
neolefty 13y ago
Seems simple to prevent: Keep an active signal loop between receiver and satellite. If something goes wrong, shut off the satellite. Worst case a couple of seconds, which with microwaves isn't long enough to do substantial damage (I suspect).

trhway 13y ago

and a movie about villains hacking in and taking control of the beam. Steven Seagal has similar one ...

puls 13y ago

I can't believe nobody has mentioned this yet: exactly this was one of the standard disasters in SimCity 2000, where "microwave" was one of the power plant types.

deleted 13y ago
[deleted]
HCIdivision17 13y ago
Thanks for saving me the trouble. Microwave tech was awesome and cost effective until the first time the satellite got out of alignment and burned half the city down. I've been terrified of the idea ever since: you just can't make a weapon like that fail safe, and if you do manage, then your throughput is too low to make it worth it.
- worldsayshi 13y ago
  What you possibly could do is to not have a single emitter but loads of them for each collector. So that a single satellite getting out of alignment would be harmless. Many emitters would need to get out of alignment pushing the beam in the same direction for it to be harmful.

XaspR8d 13y ago

Total nostalgia anecdote here, but Sim City 2000 had that as a disaster. I believe it was a constant risk whenever you built orbital-solar-to-microwave plants.

lutusp 13y ago

> Is this even dangerous, or am I off base? I know they're nervous about nuclear since Fukishima, but unless I'm mistaken there's similar risks with this option. No, not true. Don't confuse ionizing radiation as from Fukushima, with non-ionizing radiation, as from microwaves. They're very different. Microwave radiation isn't nearly as dangerous -- it can't break cellular bonds like ionizing radiation can, it can only heat things up. A microwave power system would have to pass strict safety tests, to make sure the microwave radiation level at the surface (near occupied areas) is well below that from the other big electromagnetic emitter -- the sun. That should be an easy standard to meet.

finnh 13y ago
The danger isn't from "overflow" radiation when the microwave beam is on target. The danger is when the microwave is off-target by a couple hundred feet (teensy fractions of a degree, considering the distances involved) and suddenly your concentrated 1GW beam is pointing at an apartment building. That beam is WAY more powerful than the sun per unit area. If not, we'd just use the sun.
- skorgu 13y ago
  > That beam is WAY more powerful than the sun per unit area. If not, we'd just use the sun. Not necessarily. Rectennas can get ~80% conversion efficiency, PV panels you can actually get in bulk are closer to 30. So you can have a beam about as strong as the sun and get ~triple the power out the other end by using microwaves instead of light.
  - danielweber 13y ago
    When you express what SPS is doing as "making solar 3 times more land-efficient" it looks kind of crazy. Maybe dump the billions of dollars that would be needed for launching just one of these into squeezing another percentage point out of all new solar cells.
- worldsayshi 13y ago
  Just use multiple source satellites for each destination collector. Each being harmless, together they are powerful enough for a decent output.

Someone 13y ago

Read the article. It's not massively powerful; the beam will deliver about a kW per square meter (that's a GW per square kilometer).

scott_karana 13y ago
So... it's as powerful as an unshielded microwave oven. Imagine the hideous health implications if a city block got cooked.
- spiritplumber 13y ago
  Rather than imagining it, play Sim City 2000 and see for yourself!
- e12e 13y ago
  Is it? Most (old) ovens used to be rated at 1KW, but they certainly weren't 1 square meter, more like half a square foot. You can fit quite a few half-square "feet" in a square meter (roughly 3*6 -- so 1kw/sqm would be about 1/18 of a microwave oven?).
  - scott_karana 13y ago
    True, thanks for correcting my math. I still think there could be negative health effects, but obviously they wouldn't be as pronounced. :)

Florin_Andrei 13y ago

This is probably the one thing that makes me act like a luddite - smash the darn thing before it gets a chance to even twitch a little.

danielweber 13y ago

In fact, the beam wouldn’t even be intense enough to heat your coffee. In the center of the beam in a commercial SPS system, the power density would be 1 kilowatt per square meter, which is about equal to the intensity of sunlight Of course, if it's only as intense as sunlight, you would wonder why they are bothering building a rectenna and an SPS. . .

InclinedPlane 13y ago

The trick is you don't let the microwave beam get very strong. If you keep it at a fraction of solar power (say, a few hundred watts per m^2) then it won't be that dangerous. And yet because it's RF energy instead of solar energy and consistently at the same power 24/7 it's much, much easier to build the ground based infrastructure to collect and use the power. Also, it's pretty easy to keep the beam away from populated areas.

neolefty 13y ago

Seems simple to prevent: Keep an active signal loop between receiver and satellite. If something goes wrong, shut off the satellite. Worst case a couple of seconds, which with microwaves isn't long enough to do substantial damage (I suspect).