Seth Potter says SBSP is $240/watt (was Why Sustainable Power is Uns

>> $400 of the $800 was transport to GEO. The current cost to GEO is 200
>> times higher so the transport alone would be $80,000 per kW. Plus
>> RDTE for one or a small number would be in the tens of billions. You
>> only get into the interesting range if you are producing upwards of a
>> GW/day of power sats.
>
> what, if it would be possible to construct the Solar Power Station
> as a mobile unit in LEO and getting it to GEO with it`s own HIPEP ion
> thrusters? After all, it is a power station, able to deliver as much
> energy needed to run a lot of thrusters.
> How would the costs then look like?

This was the original Boeing proposal back in the 70s. Even then
there was enough space junk that they figured it would take a lot of
repair from being hit on the way up. We can clean up all the space
junk with a big ablation propulsion laser, but if we build a laser, we
might as well use it for sending the power sat parts directly to GEO.

Also, as I recall, ion thrusters took a year to move a power sat from
LEO to GEO. That's a year you don't get revenue. One objection of
damaging the power sat by taking it through the thickest part of the
radiation belts is a non issue because we can drain the particles out
of the belts.

It's tricky building them in LEO because of the high gravity gradient
unless you make the power sats isostatic with respect to gravity
gradient. Phil Chapman has done work on this design.

I am not strongly attached to this rocket and laser kludge like I am
to the space elevator. Moving cable space elevators are just elegant
from an engineering viewpoint. They take cargo and people to GEO for
15 cents a kg in energy cost. If only we had the cable . . . . The
rocket and laser kludge is just the least expensive way I know that
will take million tons per year to GEO. But if anyone can figure out
a lower cost approach, please speak up.

Keith Henson