Solar Power Satellites

From: ANTIcarrot [dante_feditech@...]

> > From: bobunf
>
> > In a limiting case, where energy losses
> > approached zero and cost was negli-gible,
>
> Erm... 'negligible' is one word. Is there some reason you repeatedly
do
> that?

I'd mentioned that some of the arguments reminded me of Zubrin's
analysis. The above, plus the fact that one paragraph is repeated as
both the second and last one makes me wonder if this was cut-and-pasted
from somewhere.

bobunf, I'm really not trying to jump down your throat or accuse you of
any kind of impropriety, but is this your analysis, or did you cut and
paste from another reference? I only ask because I'm curious to know if
we're debating you, or essentially debating Zubrin by proxy.

> > power could be transported
> > from the most optimal locations around the Earth, and the is-sues of
> > diurnal, weather and seasonal variability for an Earth based system
> > would be eliminated.
>
> Not entirely. Since microwaves don't go round corners you'd still need
to
> transmit it either multiple times via ground stations or twice via
satellite
> and ground stations. And if you're going to build microwave relay
satellite
> that big anyway...

David Criswell (LSP advocate) likes to make the point that an orbital
microwave reflector would mass significantly less than a same-area SPS.
But the point remains that neither LSP nor the above proposal saves us
the complications of having to emplace large structures in orbit.

> > less 1% for station keeping
>
> Probably a gross over estimate.

That figure didn't raise my eyebrow the first time I saw it. But on
further reflection, I'm recalling that somebody said the average SPS
would have 10 times the power output of a nuclear reactor. So what the
above implies is that it might take 1/10 the output of a nuclear reactor
just to maintain orientation of this satellite. Maintaining orbital
altitude wouldn't even enter into it since there is no significant drag
at GEO altitude.

> > less 2% for temperature control
>
> What have you been smoking?

I've never read anything about SPS to imply that anything beyond passive
cooling would be necessary.

> > This assumes the equivalent of only one shuttle mission per year
>
> Only a complete loony would suggest using the space shuttle.

And that stood out to me too. Even before the Shuttle flew, in the era
when its capabilities were assumed to be much greater than they turned
out to be in reality, SPS advocates assumed yet more advanced space
transportation systems with capabilities far beyond even the
hypothetical Shuttle ones.

Regards,

Mike Combs