Japan proposes orbital solar farm by 2020.

[KSK]

You're partly right, but I don't think that cheap launches will increase demand. Even dividing prices by 10 will not cause launch demand to multiply by 10.

Demand is created by purpose. There needs to be a reason to put stuff in space. Space needs new applications with a decent return on investment or at least some sort of incentive. The only economically viable space activity right now is comsats. Even if SpaceX was capable of cutting launch prices from $70 million to $7 million, it won't make new applications appear out of thin air.

True. I'm curious to see what SpaceX's medium term plan is. In the short term I can see them making even bigger inroads into the comsat market, in the long term, their stated goal is Mars. How do they profitably join those two dots?

Assuming (and it's a big assumption) SpaceX can get through the red tape, I can imagine quite a few countries wanting a low cost space program for the international prestige. Whether any of them will do much more than putting a couple of nationals into space and calling it done is another matter but it could still represent a reasonable source of revenue for SpaceX.

I can also imagine cheaper access to space having a big impact on national unmanned exploration programs. Heck, the kind of costs that SpaceX is touting could bring interplanetary scale missions within budget for the larger universities or consortia of universities.

There's also the hoary old chestnut of space tourism. If SpaceX can bring the price of a Dragon flight down into single-digit, low tens of millions and if a suitable regulatory regime can be put together, then orbital flight becomes a millionaire's game rather than a multi-millionaire or billionaire's game. Dragon is set up for seven crew if I recall correctly, so even assuming two actual crew members, there's still room for three (five if they want that genuine old-school crammed-in-a-can feeling) paying passengers per launch.

More importantly, for the foreseeable future, I think the only purpose to space will be space itself. Much of the incentive for upping the launch rate will be to service existing infrastructure, whether that be orbital refueling depots, fleets of small autonomous space-junk de-orbiters or shipping guests and materiel up to Bigelow's latest. Truly sci-fi concepts like asteroid mining, space solar power and the like are a waaay off in the future for now.

As a space geek, I'm cautiously optimistic about the next decade or so though.

[Rakaydos]

SpaceX may be lowering prices, but Planetary Resources is going to be a medium term customer thats going to draw demand. Building off NASA's asteroid retrieval mission, Planetary resources wants to capture and MINE asteroids to crash the market in Rare Earths and letting the market discover new uses for the formerly expensive materials.

[ThirdHorseman]

Japan has been working on SSPS for decades, they did a huge study in the early '90s where they detailed their plans:

http://nss.org/settlement/ssp/library/1992-SpaceSolarPowerProgram(ISU-Part1).pdf

http://nss.org/settlement/ssp/library/1992-SpaceSolarPowerProgram(ISU-Part2).pdf

They did lots of wireless energy transmission experiments too, and even flew a model airplane by beaming microwaves. This is all proven technology and requires no large advances in theory.

I have been a huge advocate of SPS systems for a long time now, and I think this is definitely where the future lies in large-scale power for terrestrial and space-based applications. Some points:

1) You cannot weaponize this. As others have said, the beam density is so low you can stand in the middle of it, and the microwave generators are not large enough to create a more powerful beam so you can't just turn the dimmer switch up to burn up people you don't like. The beam cannot even move off of the rectenna as a beam guide prevents that.

2) Yes, the rectenna requires a LOT of area...but we have a lot of free space. This can be built on large floating platforms, or in desolate areas. Or you can build the rectenna right in your backyard...unlike large PV farms the rectenna does not prevent the use of the land it is built on. It allows nearly all sunlight through, so you can probably still use the land for farming or other uses.

3) Most designs focus on using large PV arrays in GEO, but I don't think that's the best way. I would go with large Stirling engines similar to those built by Stirling Energy Systems. Solar thermal systems are more robust, more efficient, and less prone to degradation than PV arrays.

4) Yes, this will be expensive. It would require evolving and expanding our space footprint as well, and as we get more involved in space the construction and maintenance costs will go down.

This site has a pretty good breakdown of the idea, as well as some nice pictures from the '70s:

http://www.wired.com/2014/04/solar-power-satellites-a-visual-introduction/