[LMB] Soletta (WAS: Chat - New Essay)

[James M. BRYANT G4CLF]

Mark Mandel claims that the soletta is impossible because:-

 >The mirrors can't reflect more energy than they receive
 >from Komarr's sun. If the soletta reflects all its energy
 >onto a planetary "footprint" with the same area as the mirrors
 >that footprint _and nowhere else_ will get full one-sun
 >insolation from the soletta in addition to whatever it gets
 >directly from the sun. If the reflection is spread out to
 >cover the whole visible (almost-)hemisphere, or indeed any
 >significant fraction of the planet's surface, it will fade to
 >insignificance. I'm afraid Her Ladyship just made a boo-boo
 >here, and I can't see any reasonable way to fix it.

But nowhere that I can find do we learn how large the soletta
is, nor do we know how efficient the greenhouse effect is on
Komarr. If the original Komarr had Earth-normal atmospheric
pressure and carbon dioxide (CO2) froze then its temperature
would have been below 195K. Without greenhouse effect or some
other mechanism to modify the fourth power relationship
between absolute temperature and radiation rate the insolation
would need to increase by a factor (273/195)^4 = 3.8 (Approx 4).
This means a soletta with three times the area of Komarr's
cross-section - if Komarr is Earth-sized this is about 150M
square miles. There are, IIRC, seven mirrors so each must be
5240 miles in diameter in the absence of any greenhouse
augmentation. This is not impossible in zero-G but station-
keeping and stability will be demanding.

In the first chapter of "Komarr" Ekaterin views the damaged
soletta and reflects that it used to look like "a snowflake
made of stars". This is not incompatible with 5000 mile mirrors
at a distance of a million miles or so - and at that distance
the mirrors would not be visible to be star-like against a day
bright post-sunset sky if they were smaller than 1000 miles or so.

An ore ship could go through a 5000 mile mirror with minimal damage
to both unless it were unfortunate enough to strike some cortical
node - but the gravitational "trough" probably did much more
damage than the actual ore ship - in fact the analysis may prove
that the ore ship was a red herring and the damage was mostly from
the gravitational pulse.

I don't see the physics/engineering as impossible - merely that
Lois did not spend as much time filling in detail as we might have
wished.

James - who has no time for a more detailed analysis