If only GEO we3e6 km in circumference (was Earth intercepts one part in)

On Feb 1, 2012, at 8:41 AM, sraj wrote:

> Next, it says: "Nine thousand such satellites could produce the
> equivalent
> of all the energy produced today (roughly 15 TW)."
>
> ...
>
> Would it be possible to safely transmit so much power by microwave to
> Earth?

I've calculated the heating, it is completely trivial. Much less
than 1/1000th or a degree if memory serves.

Analysis is need to see if beams would promote atmospheric chemistry.

It should be noted that an awful lot of electromagnetic energy passes
through the atmosphere today. Consider the Sun.

> What would be the area of the ground antennas?

Large, but quite a bit smaller than needed to generate the same power
with ground solar.

>
> Personally, to tell the truth, I feel uncomfortable with power
> satellites,
> unless someone can prove with 99.99% confidence that all this
> microwave
> will not zap the Earth.

If by zap, you mean damage a multi-thousand km rock, no. There are
specific effects that can happen and the choice of frequency makes a
big difference. Part of any major SSP project has to be an
environmental impact report. There's good reason to believe the EIR
will come out fine, but it hasn't been done. To do it properly
requires some fairly serious money, a lot more than SSP has ever
received.

It's important to remember that the alternatives, coal, gas, oil,
ground solar, wind, nuclear all have environmental impacts, some of
them pretty nasty. What SSP has to do is be better, not perfect.