The human race has an insatiable hunger for energy. Down through the ages humanity has found new sources for energy and exploited them ruthlessly. Our use of fossil fuels to power our civilization has resulted in changes to the climate that may render large areas of the Earth uninhabitable. Hopefully we will ramp up the use of non-polluting renewable energy sources in time to prevent the collapse of our society. One of the best renewable sources is solar power. However, solar power can be intermittent in many locations and, of course, is only available in the daytime. With the development of a robust private space industry, there are hopes that we can place solar power collectors in orbit where the sun shines all the time.
The idea of space-based solar power can be traced to the short story “Reason” by Isaac Asimov published in 1941. A detailed description of the idea was provided in 1968 with the first patent for such a system being granted in 1973 to Peter Glaser. A large array in space would collect solar energy which would be converted to microwaves and transmitted through a large antenna to a smaller antenna on the ground.
The California Institute of Technology (Caltech) and Northrop Grumman Corporation (NGC) formed the Space-Based Solar Power Initiative (SSPI) in 2015. Caltech was supplied with a budget of seventeen and a half million dollars for a three year project to “develop the scientific and technological innovations necessary to enable a space-based solar power system—consisting of ultralight, high-efficiency photovoltaics, a phased-array system to produce and distribute power dynamically, and ultralight deployable space structures—that ultimately will be capable of generating electric power at a cost comparable to that from fossil-fuel power plants.” One of the SSPI members said “What we’re proposing, somewhat audaciously, is to develop the technology that would enable one to build the largest-ever-built space structure.”
The SSPI is using a modular approach to help lower costs and provide redundancy. The basic unit of the system is a four inch square, one inch thick “multifunctional tile” which is a light photovoltaic cell that weights three one hundredths of an ounce. The project calls for making a panel with four hundred tiles and placing nine hundred of the panels into each satellite. Each set of panels can be folded into a small space for launch and then unfolded in orbit to about two thirds the size of a football field.
The SSPI plan calls for putting twenty five hundred of these satellites into a close formation in orbit. Altogether, this array of panels would be about three and a half square miles in size. Each tile is able to convert solar energy into microwaves that can be beamed back to Earth.
One benefit of the modular approach with the small tiles is that inevitable damage to any orbital structure from micro meteorites or orbital debris would only knock out a few individual tiles leaving the rest of the array intact to continue supplying power.
Another benefit of space-based solar power is the fact that unlike terrestrial power stations, space-based solar power does not require sophisticated infrastructure at the site of use. This makes it ideal to supply power to remote and impoverished areas. Only a relatively simple and cheap ground station has to be built with the antenna to receive the orbital power.
