Earth-Moon L1

Charles:

Are you saying that for an "L1 SPS demo" we must construct a rectenna at least "a few km diameter" on the surface
of the Moon? What area of solar PV cells at Earth-Moon L1 are you
suggesting for this L1 SPS demo? Would all of this equipment be
launched from Earth?

Ron

charles radley c.radley@...
12/19/02 09:34 AM

>

There is a minimum size for a rectenna based on microwave antenna geometry
which means that 100 m^2 would not be a
useful size.

The minimum rectenna size is about a few kilometres diameter, otherwise
the transmitter antennas must become
incredibly
large, and the microwave beam power intesity way high. The bigger the
rectenna, the smaller the transmitter antenna
size.

The optimmum sizing is where the rectenna and the transmitter antenna are
each a few km diameter.

So it is true that for small scale bootstrapping, a rectenna will not work
and we are stuck with less efficient PV
arrays.

Once we get to the breakthrough size it would go like this:

A 10 km^2 rectenna generates as much as a 50 km^2 PV array. This is
about the smallest useful size for a rectenna.

But we cannot bootstrap our way from small scale operations to a
rectenna. They are simply not dependent on each
other, i.e. the one does not need the other, nor even benefit from the
other.

I do not see the value of boostrapping from small beginnings, we can and
should jump straight do a L1 SPS demo. It
is easier to sell than the bootstrapping approach because of its economic
payback.