Describe a beamed power solution. ( Digest Number 135)

>
> The angle to the Sun will be different than the angle to the Earth
> rectenna target.
> It is not possible to focus both at once.

Why not? Couldn't the satellite be configured to have the solar collector
point at the Sun while the transmitter/reflector is pointed at the Earth
rectenna target? I could make a sketch, but I'm no good at ASCII drawing.

>
> How would the solar energy be collected ?
>
> Solar PV cells are only 20% efficient and very heavy.
>
> What you are talking about is essentially SPS, no ?
>

Heavy is certainly a big problem. But I thought the whole point of
collecting solar energy from orbit was that you could achieve efficiency
ratings above 90%. Otherwise, why bother? I don't have the reference on
hand to quote from, unfortunately. Maybe I misread it.

> But what I have been saying is that simple microwave relays are a lot
> cheaper than SPS, and could be a peofit center much sooner.
>
> What you are proposing is the reverse of my proposal.
>

Not quite. I'm trying to figure out how we can maximize the power output
from these satellites we're putting up into orbit. I'm not saying we
shouldn't use simple microwave relays. All I'm suggesting is that if we
put the equipment we're talking about into orbit, how much more work would
it be to put a solar collector on top of them to add to the power they're
already redirecting back to the Earth rectenna. If it's a huge cost
increase with a small power boost, then never mind. But if it's a small
cost increase with a decent boost in transmitted power, then it's
something to consider.

--Justin