I mentioned the idea of developing and building
a 100 meter wide, 300 meter long, experimental-prototype
orbiting solar-energy plant to generate enough power beamed to Earth
to light up a small city of between 20,000-50,000 people.

Such a "small' prototype orbiting solar-energy plant
would show politicians, taxpayers and critics that space-based
solar-energy plants would be useful.

Later, I checked out some calculations showing that such a 100m x 300m
orbiting solar-energy plant would weigh less than 1000 metric tons, if you
could keep the silicon wafers to a thickness no more than one centimeter.
Light-weight lithium-aluminum girders and a wiremesh-covered microwave beaming
dish would be less than 20 percent of the weight of the silicon in the orbiting structure.

1,000 metric tons would require only 10 HLV launches to park the sections in LEO.
(The launches could ideally be carried out within a 12 month period)
Ion rockets could then slowly push the assembled/completed structure to GEO where it would stay.

But I did mention that there can be ONE solution to THREE different needs
and tasks; and all it would require is that such an orbiting solar-energy plant
continue to....grow over time...with an increasing area of solar-panels added
regularily until it you have a humongous solar-energy plant, with an area
over one square kilometer, in geostationary orbit....That's enough solar-energy
collected to generate over 300,000 KW of microwave or light energy (for an
extremely powerful laser).

(1) A 300,000 KW laser in GEO orbit could knock out ballistic-missiles launched from
rogue nations.

(2) That 300,000 KW laser could divert NEO asteroids that threaten Earth.

(3) That 300,000 KW laser. though not as powerful as the one the late Robert Forward
suggested be used to propel a 20 gram mass, gossamer-thin "light-sail probe" to a nearby star,
can still be used for the same purpose, though it would take eight times longer
to accelerate that kilometer diameter light-sail probe.
If Barnard's Star were targeted, it would take over 40 years for such a probe
to reach it; but look how long scientists waited for the results from Gravity-Probe B?
A probe that was first conceived over 40 years ago.

Cheers.

Jacob

John F. Kennedy "We choose to go to the moon, and do those other things, not because
they are easy, but because they are hard."