[ExI] pentagon wants orbiting solar power stations

[hkhenson]

At 08:44 PM 10/12/2007, you wrote:
>In what form is the energy being beamed back to Earth?
>
>If Microwaves or lasers this sounds like it could easily be used as a war
>machine making it a high value
>target in any conflict we are likely to find ourselves in.

This was developed back in the heart of the cold war, so the design 
was such that they could not be used as weapons.  The microwave beam 
is only about 1/4 as intense as sunlight for that reason (but the 
collector are a lot more efficient and less expensive).  They can't 
be focused any better because they are at the diffraction limit for 
the wavelength being generated by the transmitting 
antenna.  http://en.wikipedia.org/wiki/Airy_disk

Put in the numbers for the distance to GEO and the wave length and 
the transmission diameter

>Also if the targeting system was ever hacked or malfunctioned it could
>become a more powerful terrorist weapon than an
>atomic bomb by lighting major cities a blaze or bombarding highly populated
>areas with intense microwaves.

In order for the power to come down where it is wanted, the designers 
had to use a pilot beam that phases all the transmitters.  If that 
failed, the transmitter disk went incoherent and the microwaves no 
longer focused.  Now you could capture the beam with a mobile pilot 
beam transmitter and drive from a rectenna into town dragging the 
beam along with you.  But it's not much of a weapon when it will only 
add about 25% to the sunlight and can be warded off by a tinfoil hat.

Lasers, because they have a *much* shorter wavelength are a different 
story.  I once did a story (though I can't find it now) about someone 
on a speaking platform who calls for ghod to strike him down if he is 
not telling the truth.  There is a shaft of light from the heavens 
and a cloud of smoke drift's downwind.

>I would love for this form of power be the solution to all of our energy
>problems but I can't see this happening without
>major opposition from other countries and skeptics who would fear the worst
>perhaps with good reason.

There is a decent case to be made (I made it here recently) that SPS 
energy could get down to the point of making dollar a gallon 
fuel.  There is no other carbon free method for making baseload power 
except nuclear.

>I understand that the government would build in lots of failsafe mechanisms.
>But sell other countries and the average
>American on the infallibility of such a system would be nearly impossible.
>
>When I compare this in my mind to new nuclear designs, the nuclear seems a
>lot less controversial and easier to
>implement and we're have trouble getting any of those approved.

There is an unrecognized problem with anything that generates 
neutrons.  They can be used with a little plumbing and some depleted 
uranium to make exceptionally high grade plutonium, stuff you can 
convert into bombs with the resources of a decent sized street gang.

The *big* problem with SPS is getting 2000 tons a day out to 
GEO.  Think 2 Saturn 5 launches an hour.  But if you can make a 
moving cable space elevator, you can do it with a big motor driving the cable.

Keith