On Thu, Jul 27, 2023 at 5:57 PM Kathryn or Steve Leete
> I've been trying to promote an idea if a few venues regarding SSP. The idea is that SSP should start in LEO or MEO.
> Getting started with SSP is quite different from getting started with satellite communications. With SatCom, it made perfect sense to start at GEO. From GEO you can provide useful comms to a vast swath of the Earth with a single satellite. You can start with decent bit rates, point to point from anywhere within the very large area covered by an earth coverage antenna. For a modest antenna size, transmitter power, and a simple bent pipe system, it's useful immediately.
> Try to replicate that early stage with SSP, and you produce nothing of any value at all. To make the first GEO SSP useful, it will have to be enormous, and it will only provide power to a small area at a time. To keep the promise of continuous baseband power 24/7 at levels useful to cities, you need to dedicate each satellite to one city.
I have considered this in some detail. What makes the most sense is
just to dump the power into the grid. For example, there is a power
line from Mojave over to LA that runs through some uninhabited areas
that would be ideal for a rectenna.
> Alternately, you could hop the beam around, but now you are getting less payback for the ground infrastructure at each location, and if intermittent power were OK why not stick to wind and solar?
My estimate for a 5 GW rectenna is a billion dollars out of $12 B for
the whole thing.
> My thought for some time is that SSP needs useful stepping stones. Now that we know we can operate LEO constellations of thousands of satellites with a modest cadre of operators, let's apply to at logic to SSP. A MEO constellation will be on par with wind and solar, but the intermittency will be highly predictable and can be planned on. Each satellite will be contracted to provide service to various customers on a schedule as it passes over them. As the constellation is built out, clients can carve out power that gradually builds up to constant. Consider the number of GPS satellites we have, and how many are in view worldwide at any time. A similar number of MEO SSP satellites could provide similar possibility of continuity. A city that is far from other cities could readily rely on the constellation.
I don't think this gains enough over GEO to be worth it. MEO or GEO,
the cost of producing power is not much different. Reducing the
distance to half cuts the transmitter diameter by half and the mass to
1/4, but the transmitter is not a large fraction of the total mass.
One problem is that the beam comes in at varying angles, increasing
the rectenna area. MEO does reduce the amount of reaction mass needed
to move the power satellite out of LEO, but it is less than you would
think because most of the delta V is getting up to MEO and from MEO to
GEO is not that much.
> The sats are easier to get to MEO than GEO, can be sized to each fit into a Starship or comparable HLV, and either deploy out or be assembled by robotics.
Absolutely no way. It takes about 100 Starship launches per GW.
> What do you think?
> Steve Leete