[LMB] Soletta design, and moons more generally.

Baur baur at chello.at
Sun Oct 21 08:05:11 BST 2018


Am 21.10.2018 um 04:58 schrieb pouncer at aol.com:
> I don't see the need for a moon, UNLESS the soletta is at a Lagrange point.
> 
> As has been identified, the target of the redirected sunlight is anyplace on
> Komarr's surface.  There is no need for a geostationary orbit.  There is
> no need for an equatorial orbit -- orbiting over the poles, perpendicular
> to the equator, works too. That the soletta has several mirrors suggests
> that they can be tilted, like sails, to adapt to orientation with respect to
> light and solar wind, and to use the pressures of either to slowly change
> position.

or the soletta is a system / swarm of several free flying mirrors - this 
would have the advantage that you could out it into operation even if 
only a small part of the whole system is finished .. it also allows you 
to improve mirror design iteratively and to take part of system out of 
operation for servicing / refurbishment / improvement / scrapping as 
necessary
> A disadvantage of distant orbits, either Lagrangian or geo-stationary, is
> that unless the mirrors are optically perfect, or nearly so, the reflected
> light disperses, falling with the square of distance. (With a perfectly
> flat mirror, the (nearly) parallel rays from the Komarran sun remain
> parallel when sent down.

for the purpose of terraforming the optical quality of the mirror(s) 
need only be good enough that a majority of reflected sunlight reaches 
Komarr SOMEWHERE - the purpose is not optically perfect lighting, after 
all ..

for 12000 km diameter at 300000 km distance the cone angle (and thus the 
necessary accuracy of the mirror) is 2.3 degrees .. NOT very flat ..

> But if the mirror is fabric or a bunch of
> panels,  the light scatters as it is reflected.) So an near orbit that keeps
> all the reflection hitting the surface is better.  There are trade offs
> between keeping the soletta far out of the shadows and near enough
> the surface.

one of the disadvantages of a close soletta is that it makes fast slew 
rates necessary to deal with the rapidly changing sun position .. fast 
slew rates in something as large and fragile (they are built as light as 
possible, or they would be much more expensive than they already are) 
are problematic as you risk distortion of the structure due to 
maneuvering and centifugal forces

and a close soletta would not fit with the canon light speed lag of 
several seconds ..

servus

markus

> The discussion makes me wonder about Barayarr's moons. Is there
> any chance at least one of the (two, small) moons is artificial?  Say,
> while the Firsters still had ships in-system, a comet or even a natural
> irregularly orbiting moon was shifted into an orbit that was not-quite-
> geostationary.  I wonder if a moon, with a 24 hour period,  wouldn't
> be useful to a word with a 26.something hour rotational day.  A way to
> compare an astronomical clock of Earth-standard-time against local
> time.  (This sort of assumes the ship-in-system is a tug or shuttle that
> has crew reacting to the realization that the JumpShip, mothership, colony
> planting vessel is NOT coming back... )
> 
> 
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