How Japan Plans to Build an Orbital Solar Farm - IEEE Spectrum

[bananas]

Lots of information in the article, I snipped out everything except the near-term timeline: they're planning ground-testing of beam-steering this year; sending several kilowatts from low earth orbit in 2018; and a 100kw demonstration satellite around 2020.

http://spectrum.ieee.org/green-tech/solar/how-japan-plans-to-build-an-orbital-solar-farm

How Japan Plans to Build an Orbital Solar Farm
JAXA wants to make the sci-fi idea of space-based solar power a reality
By Susumu Sasaki
Posted 24 Apr 2014 | 14:00 GMT

<snip>

It’s been the subject of many previous studies and the stuff of sci-fi for decades, but space-based solar power could at last become a reality—and within 25 years, according to a proposal from researchers at the Japan Aerospace Exploration Agency (JAXA). The agency, which leads the world in research on space-based solar power systems, now has a technology road map that suggests a series of ground and orbital demonstrations leading to the development in the 2030s of a 1-gigawatt commercial system—about the same output as a typical nuclear power plant.

<snip>

In Japan, we are now planning a series of demonstrations for the next few years. By the end of this year, researchers expect to perform a ground experiment in which a beam of hundreds of watts will be transmitted over about 50 meters. This project, funded by JAXA and Japan Space Systems, will be the world’s first demonstration of high-power and long-range microwave transmission with the critical addition of retrodirective beam control. The microwave transmitter consists of four individual panels that can move in relation to one another in order to simulate antenna motion in orbit. Each panel, measuring 0.6 meter by 0.6 meter, contains hundreds of tiny transmitting antennas and receiving antennas to detect the pilot signal, as well as phase controllers and power management systems. Each panel will transmit 400 W, so that the total beam will carry 1.6 kW; in this early-stage experiment, we expect the rectenna to have a power output of 350 W.

Next, JAXA researchers hope to conduct the first microwave power transmission experiment in space, sending several kilowatts from low Earth orbit to the ground. This step, proposed for 2018, should test out the hardware: We hope to demonstrate microwave beam control, evaluate the system’s overall efficiency, and verify that the microwave beam doesn’t interfere with existing communications infrastructure. We also have some space science to conduct. We want to be sure that the intense microwave beam isn’t distorted or absorbed by the plasma of the ionosphere, the upper-atmosphere layer that contains electrically charged particles. We’re pretty sure that the beam won’t interact with this plasma, but our hypothesis can be confirmed only in the space environment.

If all goes well with these initial ground and space demonstrations, things will really start to get interesting. JAXA’s technology road map calls for work to begin on a 100-kW SPS demonstration around 2020. Engineers would verify all the basic technologies required for a commercial space-based solar power system during this stage.

<snip>

Throughout human history, the introduction of each new energy source—beginning with firewood, and moving on through coal, oil, gas, and nuclear power—has caused a revolution in our way of living. If humanity truly embraces space-based solar power, a ring of satellites in orbit could provide nearly unlimited energy, ending the biggest conflicts over Earth’s energy resources. As we place more of the machinery of daily life in space, we’ll begin to create a prosperous and peaceful civilization beyond Earth’s surface.

[hr]
This article originally appeared in print as “It’s Always Sunny in Space.”

About the Author

Sasaki, a professor emeritus at the Japan Aerospace Exploration Agency, spent much of his 41-year JAXA career researching space-based solar power systems. The best-case scenario for this technology, he says, is a global “paradigm shift” in which nations stop competing for energy resources on the ground, and instead work together to build grand orbital power stations that beam clean energy down to Earth. He remains optimistic.

[chrisstopher]

1. Not only will it give them cheap power

Roasted birds will fall from the sky.
I wonder how roast seagull tastes?

[forsaken mortal]

2. Perhaps not

We might have to take roasted seagull off the menu. From the article:

"When laypeople hear these orbital solar farms described, they often ask if it would be safe to send a powerful beam of microwaves down to Earth. Wouldn’t it cook whatever’s in its path, like food in a microwave oven? Some people have a grisly mental image of roasted seagulls dropping from the sky. In fact, the beam wouldn’t even be intense enough to heat your coffee. In the center of the beam in a commercial SPS system, the power density would be 1 kilowatt per square meter, which is about equal to the intensity of sunlight. "

[LongTomH]

3. The energy levels of the microwave beam, even at the center of the pattern, is far below levels.....

.....that could 'cook' flesh or even cause short-term tissue damage. That was dealt with in the NASA/DOE studies of the solar power satellite back in the 1970s, This sort of disinformation helped kill off the US space solar power effort, and left the lead to Japan and China.

[LongTomH]

4. I remember the old days of the L-5 Society, when we were promoting solar power satellites and.......

......Dr. Gerard K. O'Neill's work on use of lunar materials to build SPS.

I'm willing to bet that Japan is already looking at use of lunar or asteroid materials in solar power satellite construction.

Edited to add: I wish the US was working with Japan on this; sadly, this is unlikely, with the US Congress being a wholly owned and operated subsidiary of big carbon, especially Koch Industries.

Maybe some private US companies, like SpaceX, will be part of the consortium led by JAXA to build the first SPS.

[yurbud]

5. the US is probably working on coal, oil, and gas extraction in space

and returning the stuff back to Earth to burn here.