Crisewell's LPS

>Criswell has yet to address those comparison issues. For him to only
>compare to Earth-launched SPS is a strawman argument, for serious
>students of the subject are aware of the O'Neill proposal.
>
Criswell does compare his project with the O'Neill approach, in several
of his articles. I believe in his view the O'Neill solar power satellite
is an excellent long-term solution, but lunar solar power is better in
the intermediate term because if you are using lunar resources, why not
use it on the lunar surface first? I'm somewhat agnostic on the issue,
but I'll argue his points anyway.

>
>1.) Both excavate lunar resources, but Criswell needs to refine and
>fabrciate on the Moon. O'Neill needs to have mass driver launch,
>mass catcher and orbital refining and fabricating. What are the cost
>differences between the two schemes?
>
Criswell would argue it is clearly cheaper to do the mining and
fabrication in situ using mobile processing robots. The processing
required to turn lunar ore (mostly silicon dioxide) into silicon
photovoltaic cells is relatively simple. But I think this is one of
those arguments that will only be resolved with some real experience to
get numbers from.

>
>2.) Criswell needs to have a lunar girdling power cable and multiple
>solar and transmission sites; O'Neill only one SPS.
>
I don't think he uses a girdling power cable; in his Industrial
Physicist article, Criswell had a set of "power plots" that transmitted
locally generated power; one set of "power plots" on the east limb, and
one on the west. But there is a minimum size to Criswell's scheme that
would make it possible, resulting in a rather high up-front capital cost.

>
>3.) Criswell needs to address massive thermal expansion issues
>associated with lunar day/night; O'Neill doesn't.
>
I don't know about "massive" but it's certainly an issue.

>
>4.) Criswell needs to deal with beam coherence from 250,000 miles;
>O'Neill's microwave beam only travels 36,000 miles.
>
But Criswell takes advantage of the size of the Moon (power plots can
easily extend across 300+ miles) while one O'Neill-type satellite has to
be 40+ miles across to have the same beam coherence. Criswell is
actually ahead on this one - as long as the electronics of coordinating
a microwave beam across 300+ miles is doable (and it seems perfectly
practical from the things that have been done with radio telescope
interferometry).

The big disadvantage of Criswell's approach is the high up-front capital
cost. But for an O'Neill solar power satellite based on a lunar mass
driver, the up-front capital cost may well be higher. That's basically
point #1 - we don't know yet.

Seth Potter's 1999 article (I found it on the web somewhere - maybe the
SSI site?) on "Architecture Options for Space Solar Power" has an
excellent discussion of the pros and cons of various space solar power
schemes, including Criswell's - but not including a geosynchronous lunar
materials-based option similar to O'Neill's.