Friday, October 19, 2007

Space-Based Solar Power

Last week, the Pentagon issued a report urging research into space-based solar power. I sincerely hope that they follow through with this: space-based solar power could solve our energy problems forever while simultaneously providing the much-needed economic justification for space exploration.

Space-based solar power works by placing satellites with huge solar arrays into geosynchronous orbit, so that they orbit once every 24 hours, thereby staying fixed over a certain point on Earth. Unlike the space station, which orbits the earth at an altitude of about 320 km, a satellite in geosynchronous orbit is very high (about 35,786 km above the earth's surface). That means that instead of being plunged into darkness every 90 minutes like the space station, a satellite in geosynchronous orbit is constantly illuminated by the sun. This is obviously an advantage over earth-based solar power, which has to contend with pesky things like nighttime and weather.

Like giant space-faring sunflowers, the solar power satellites would constantly face the sun, collecting millions or billions of watts of power (depending on the size of the satellite). The satellite would then beam the energy down to earth in the form of harmless microwaves (similar to those emitted by cell phones), which could be received by arrays of antennas and converted directly to electricity. The energy produce by space-based solar power would be clean, unlimited, and available anywhere at any time.

Compare this with the polluting, limited supply of oil that we must buy for ever-increasing prices from unstable parts of the world. Add on the fact that you could conceivably use space-based solar power to beam energy directly to military forces in the field, and you can see why the Pentagon is interested.

There are some difficulties: particularly that access to space is not cheap. However, I think that once space-based solar power is demonstrated to actually work, there will be more interest from energy companies. With more interest, come more launches, and more launches means cheaper launches. Once launches are cheaper, it will open the floodgates to space access. As the Pentagon report says: "Solving these space access and operations challenges for SBSP will in turn also open space for a host of other activities that include space tourism, manufacturing, lunar or asteroid resource utilization, and eventually settlement to extend the human race."

I may be overly optimistic, but I think that if space-based solar power really takes off, it could be a major turning point for humanity. Unlimited clean energy will allow us to do amazing things on Earth, and cheap access to space will allow space exploration like we've never seen before.


Kevin said...

Whenever I read things like this I want to cheer.

Erin said...

"Like giant space-faring sunflowers..."

Best phrase ever. Well done.