No, actually what I’m saying is, given a transmission frequency and a distance between a transmitter and receiver, there is a relationship is the sheer size of the transmitter and the size of the receiver necessary to transmit power at a given efficiency. One of the things that shocked me about SSP was discovering that for a given frequency, distance, and efficiency, the size of the transmitter and the size of the receiver is independent of power transmitted. In other words, you have to build a huge transmitter and a 10km rectenna whether you’re transmitting a milliwatt or a gigawatt.

That kind of unfavorable scaling means that subscale SSPs will either suffer from horrible inefficiencies or require full-scale transmisssion and reception apparatuses. It is that difficulty in earning the first bit of revenue from SSP that was one of the huge economic drawbacks in the model.

In-space solar power for Earth consumption:
As I’ve said in another comment somewhere I don’t see Earth as the primary market but… saying it’s impossible as in forever un-economic even with zero launch costs?

Kirk; what you are really talking about are the problems regarding energy transmission (and more precisely microwave beams) through the atmosphere, isn’t it? It doesn’t really have anything to do with launch costs or structures or anything except the properties of the atmosphere and how good it is at weakening all kinds of radiation right? (And lucky us that it is I might add). If so I agree but I still wouldn’t rule out that the future might hold work-arounds: there’s still so much we don’t know.

I don’t see anything in that concept that addresses the basic problems of SSP–still a big transmitter and a big receiver…and there in the middle of the paper is the LV we were working on at Georgia Tech. The very model I told you didn’t close.

There are couple of critical tech hurdles in the “large solar sat” concept. Beamed power through atmosphere, large assembled structures in space are the obvious ones. Take out one of these with some out of the box thinking and you remove the constraints that make the game unwinnable.
BTW, there are other applications to beamed power than getting suns energy down to earth, so a incremental approach utilizing this tech is possible.

So most late teens twentysomethings don’t seem very interested in space. It was this way 20 yeas ago too. Water is still wet and the sky is still blue.

People in this demoraphic are interested in going to college, getting laid, getting wasted etc, etc. In othr words, they are still self-absorbed same as every post WWII generation.

Its called being a young adult and its nothing new.

Fortunately, it isn’t fatal for the most part to either them or NASA.

They may be too lazy to care enought to support the VSE but they are also too lazy to care enough to kill it.

Occam’s Razor is a wonderful thing.

Every assumption that could possibly be favorable to SSP was assumed, and then some (like free launch).

The structures are just too big and the transmission system too complex and lossy. Everything adds up and you can’t make money. Take a look at this:

http://entropyproduction.blogspot.com/2006/07/solar-power-satellite.html

The failure of SSP and fusion to hold up to scrutiny is one of the reasons I took another look at fission and discovered the potential of thorium and the fluoride reactor…but that doesn’t require a space program.

I’m personally a bit skeptical of the near to medium term viability of space solar power, but hearing “it’s impossible to make the case close” makes me suspicious about the underlying assumptions.

~Jon

The really telling moment for me was when we assumed launch costs were zero–it still wouldn’t close economically. Zero launch cost eliminates any advantage of using lunar materials or asteroid materials.

I don’t know how to make money in space, but I know it’s not space solar power.

(and we were assuming awesome performance for the SSP: 50% efficient solar arrays, no radiation degradation, $0.25/kWhr electrical power sold on the ground…still didn’t close)