starship-design: Preliminary Design for a Solar Laser Power Station

["L. Parker" <lparker@cacaphony.net>]

Preliminary design for a Solar Laser Power Station
 
OVERVIEW
This is a design for a solar powered laser that uses a sail as both the 
concentrator and the station keeping propulsion. It consists of an annular 
solar sail with an aperture in the middle to pass a beam through, a solar 
powered laser (this is technically not a laser since it will radiate 
coherent radiation in multiple frequencies) and station keeping, focusing 
and aiming controls. It is designed to be low cost, and low maintenance as 
well as easily mass producible using only moderately intelligent automation.

OPERATIONAL DESCRIPTION
	Sail Operation
This is NOT an orbital design. It is designed to kill its orbital velocity 
by tacking a solar sail until it is oriented to accelerate directly away 
from the sun with a thrust that is equal to the gravitational pull plus a 
reserve component of thrust to offset the pressure of the laser. Sunlight 
is collected by the sail in the normal manner but the geometry of the sail 
is such as to concentrate the reflected sunlight at a solar laser suspended 
where the ship would normally be.    
	Laser Operation
The laser is basically an optical concentrator whose geometry produces an 
extremely concentrated, nearly coherent beam of SUNLIGHT. Because the beam 
is not completely coherent and consists of multiple spectra, it cannot be 
truly considered a laser, but in most respects (and for our purposes) it 
behaves like one.

ADVANTAGES
1)	No onboard fuel or resupply of fuel is necessary. All power can be 
	derived from sunlight for both its primary mission (the laser), 
	station keeping and electrical power generation for on board 
	electronics.
2)	Simple to build
3)	Greatest conversion efficiency
4)	Mass producible from material found off of Earth
5)	Technically there is no limit on how big the generator can be.

DISADVANTAGES
1)	Station keeping is likely to be tricky when coupled with aiming 
	mechanisms. May cause additional beam jitter requiring extra 
	generating stations to provide surplus capacity.
2)	As beam angle diverges from solar thrust angle additional steering 
	is required to compensate for the sideways vector. There is probably 
	an upper limit to the beam angle which can be generated and therefore 
	an upper limit to how many can be aimed at one target.
3)	Continuos proximity of the sail to a sun is likely to cause 
	additional wear in the sail material due to the thicker solar wind. 
	Because of the lack of orbit, rendezvous for repairs is unlikely.


Lee Parker
                                                          (o o)
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"I share no man's opinions; I have my own."

Ivan Sergeyevich Turgenev, Fathers and Sons, 1862