I have a design question ...

--- In spacesettlers@yahoogroups.com, Steve Long wrote:
> The discussions of SPS base the possibilites on a giant satellite
> covered with solar cells converting sunlight to gigahertz-microwave
> energy and beaming it to a receptor on the Earth's surface somewhere.
>
> It seems to me that only a geosynch power satellite can be aimed at
> its receiver all the time; and a geosynch satellite will be in earth's
> shadow some fraction approaching half of every day.
>
> How is this to be countered? Am I missing a factor?
>
You seem to be thinking in two dimensions. Think of a line connecting
the Sun and the Earth in the xy plane. The SPS is at a right angle to
the sun-Earth line. In the yz plane, it is above or below or beside
the Earth. But never in a line with the Earth and the Sun.

I hope that's clear.

>
> Also:
>
> ANTIcarrot wrote:
> >
> > At the current rate of 0.12c/kwH, 1GW-Year is worth just
> > over one
> > billion dollars. A 1GW array would weigh roughly 10,000tons, and
> > would have
> > a lifespan of between 20 and 30 years. Then it would be recycled
> > into a new
> > SPS. (Assuming no advance in technology for simplicity's sake.) So
> > if you
> > can launch ten thousand tons to GEO for less than $21B then you can
> > make a
> > profit. This works out to a total construction cost limit of
> > $2,100/kg. Then
> > you rysk the SPS onsite (no launch costs!) and the next lifecycle is
> > almost
> > pure profit.
> >
> We need to get moving on an orbital heavy lifter, then -- current
> technology launch-to-orbit costs are well over ten times that,
aren't they?
>
> In comparison to these costs, what does it cost to build a 1-gw clean
> coal tecnology generator, which may last longer than 30 years?
>
> What conversion efficiency factors are built into your numbers? A
> satellite that absorbs a gigawatt/hour of solar energy will not emit a
> gigawatt/hour of microwave power, and the antenna that receives a
> gigawatt/hour of microwaves will not produce a gigawatt/hour of
> useable alternating current. I think you've left out the costs of
> construction, too, -- you've only included the cost of getting the raw
> materials for the SPS platform to orbit. Shall we pay those workers,
> or use Pharaoh's approach? :-)
>
> Remember the engineer's rule of thumb: Make the absolute best
> time-and-cost estimate that you can -- and then double the time and
> quadruple the cost. :-)
>
> Steve

Not to mention doubling the safety factor, which ups the cost.

Rick Brooks