Correcting my own math (was If only GEO we3e6 km in circumference)

On March/02.2012 23:19, Al Globus wrote:

> I do not think the spacing between sats needs to be nearly as large as
> proposed. I don't know where the numbers came from, perhaps comsats.
> SSP doesn't need to space like comsats because each is transmitting to
> a different antenna so there is no interference. Thus, so long as the
> sats don't run into each other (or anything else), its fine.

>
> Also, particularly in the high numbers case, these sats will need some
> propulsion for station keeping. Probably solar electric, there's
> plenty of power!

Hi Al,
I would propose a combination of solar sailing and solar electric.
Solar sailing could provide the fuelless propulsion part for station
keeping, steering and pointing, while solar electric would be used to
place the power sat from LEO into GEO or allow other orbits than GEO or
even change orbits as needed.

Using sail panels covered with or made of solar cells, connected with
conductive threads, would allow to launch or construct in space large
thin film solar cell areas along with the sail-power sat.

As such a sailcraft has ample cell area for power generation, the
generated power could be used to operate very fuel efficient electric
thrusters, like the new ESA/ESTEC DS4G ion thruster, which is about
eight times as efficient as regular ion thrusters (about 250 km/sec.
ejection speed).
To use such thrusters in regular satellites would be not possible, since
the energy needed to power them is not available.

"Roller Reefing" would be a way to combine power generation, fuelless
station keeping, steering and pointing and would allow also to launch or
construct large solar cell areas in a simple and relative inexpensive way.
See the paper Solar Sailing and solar power generation by
'Roller-Reefing' http://solar-thruster-sailor.info/PaperISSS2010V7.doc

With a large customer base one can easily imagine
> refueling sats that go from PowerSat to PowerSat refueling with
> whatever the reaction mass is.

For operating the craft without refueling for most of the mission time,
fuelless seems to be the best option to go. For simple refueling through
docking a mobile thruster unit I would propose this:
http://solar-thruster-sailor.info/figs/fig16.html

For more information on Solar Sail Power Stations see also
http://www.solar-thruster-sailor.info/PresentationISSS2010V13.pdf

Best wishes

Frank