Low cost power sats

>Your assumptions on launch costs don't make sense. Just building
>that many launch vehicles would lower their cost substantially
>through mass production. And launching to LEO, then using cheaper
>methods to tug the satellite to GEO would also bring the costs down a lot.

Expendable rockets won't come down that far even with substantial
production. Reusable rockets with the performance to get to LEO are
technically hard and even they don't look like they will not get the
cost down far enough. Most optimistic people I know think it will be
at least three times too expensive. Re cheaper methods, even back in
the 70s they figured an SPS would get hit several times with the
space junk that was around then. There is also the factor that you
can't use the power sat while it is in transit which was around a
year IIRC. That badly impacts the bottom line.

>But I certainly agree that launch costs have to come down. The
>problem is somewhat a chicken and egg situation: to get the costs
>down you need the demand that would permit mass production; to get
>the demand, you need more practical launch costs.
>
>Committing to a large scale SSP program would break the logjam.

Right, but you can't make a case for a program if you can't show it
will pay off big time. And the transport is currently the big ticket item.

>By the way, the problem isn't "just" replacing existing dirty energy
>sources, but addressing increasing planetary demand. And finding
>"10,000-20,000" neighborhoods willing to invite in a nuclear power
>plant would be quite a trick.

Current demand is about 15 TW. So 20,000 1 GW reactors would give
room for a little growth. Your point about NIMBY is probably correct.

What I am proposing is a *radical* departure from current rocket
practice. Mass ratio 3 rocket will get to it's exhaust velocity
(less gravity and air drag). Mass ratio 2 rocket will get to 70% of
it's exhaust velocity. The laser stage is 1/6th of the first stage,
the payload fraction of the laser stage is 1/2 in a fully developed
system. So one part in 12 reaches GEO. Pure rockets get about 1
part in 60 to GEO. This really is rocket science.

The lasers are estimated to cost $10/watt counting all the power
conditioning and related optics. So $40 billion gives you 4 GW of
laser. That's enough to raise 1300 t per day to GEO or about 470,000
t per year. $40 billion expensed over ten years is $4 billion. So
the laser part of the lift cost is under $10/kg. ($4 billion / 0.47
billion kg) Writing off big capital equipment that fast is not the
usual practice, but it's very conservative business analysis.

Keith