[dwpdwpdwpdwpdwp]

"Each megasat could then convert gigawatts of power into a microwave beam aimed precisely at a big field of receiving antennas on Earth. These rectennas would then convert the signal to usable DC electricity."

What are the consequences if, for some reason, the aim becomes not-so-precise?

[bell-cot]

Vague recollection from studying this years ago...

The "receiver" is more-or-less a field "covered" by a spiderweb of bent coat-hanger wire. That doesn't block the sun, and making it huge (low power/sq. m) is quite cheap.

Since you don't want clouds/rain/fog to block the microwaves, the frequencies you use are ones which water does not absorb well. So if the beam hits a person...he probably can't even notice it.

[_fizz_buzz_]

But electronics probably would. I have fried a micro-controller with a leaky industrial microwave waveguide before.

[bell-cot]

Yes and no. On the (figurative) day when microwave power transmission becomes normal, designing & building electronics so they are relatively immune (or can leech power if needed) will also become normal. Because stuff that isn't immune will go wonky in enough circumstances (driving near a ground receiver, etc.) that consumers will notice, and get pissed.

[marcosdumay]

I guess SimCity 2000 guaranteed this is the first thing everybody thinks about.

It seems that practicality and efficiency concerns limit the beam at between 10% to 30% of the solar intensity. Every single design falls in that range.

[throw9474]

Yes the safety is absurdly bad https://wikipedia.org/wiki/Space-based_solar_power#Safety

[dirkt]

Which sort of leads itself to military usage...

And Wikipedia is only talking about humans, not about electronics, which are much more sensitive to microwaves. Want to fry the enemy's electronics? Just focus that "civilian" microwave transmitter with a few GW power tightly on where you want it to be.

I am really surprised nobody talks about this whenver space-based power transmission is mentioned.

[throw9474]

If you trace the money, every researcher working on space based power is getting money from DoD.

[pfdietz]

The beam is controlled by a signal beamed from the rectenna, which controls the phase of the emitters at the satellite. If this fails, the emitters go out of phase and no beam is formed.

[TheLoafOfBread]

1) That's a happy path which might or might not work during malfunction. Imagine a terrorist deliberately disabling an original control signal and then using his own control signal to steer the beam on the city.

2) Beam can be used as a weapon if you will just point it and light it up and thus deploy would be sooner or later heavily restricted or outright banned like nuclear weapons in space are banned.

[banish-m4]

Futurama predicted it: https://youtu.be/0qksm5cRtcU

Unfortunately, most of these impossible proposals lack any form of passive failsafe. Plus, the insurance liability question maybe an unsurmountable unknown.

[snickerbockers]

most of these proposals are downright ridiculous because they're couched in environmentalism but they act like nature will be totally fine to have a giant microwave laser or an artificial second moon.

[micromacrofoot]

It seems like it could be safer/easier to charge batteries in space and ship them back down... which probably speaks to the feasibility of ideas like this.

[eagerpace]

Goldeneye

[simonblack]

And what if the aim is deliberately aimed at an enemy city?