Soaking in the Sun’s Rays

One of the greatest challenges facing the 21st Century is the issue of power—how to generate enough of it, how to manufacture it cheaply and with the least amount of harmful side-effects, and how to get it to users.

The solutions will have to be very creative—rather like what the Space Solar Power Initiative (SSPI), a partnership between Caltech and Northrup Grumman, has devised.

Prototype of the "multifunctional tile." Credit: Caltech

“What we’re proposing, somewhat audaciously, is to develop the technology that would enable one to build the largest-ever-built space structures,” says Harry Atwater, a Caltech professor and member of SSPI.

The idea, for beaming solar energy to Earth from space, is ingenious, simple, and may just work—given the needed investment and financial backing. SSPI has engineered a modular approach which ensures low-cost and redundancy. The basic unit is a “multifunctional tile,” a lightweight photovoltaic segment that measures 10 x 10 cm (4 x 4 in), is only 3 cm (1 in) thick, weighs about 0.8 gram (0.03 oz.), and can flatten when assembled for launch.

400 of these basic tiles are assembled into panels, with 900 panels per satellite. Each of these “carpet” satellites can be folded into a small space for launch, and unfurl once in orbit to its full size, about two-thirds the size of a football field.

The concept involves 2500 of these satellites flying in a close formation, forming a solar power surface of 9 square kilometers (3.5 square miles). Each tile is capable of converting solar power into transmissible radio energy, which can be beamed to (and received on) Earth.

Power For All

SSPI's design for modular, space-based solar power. Credit: NASA

The beauty of this system is that there is no need for a costly energy infrastructure on the Earth. This means remote and impoverished regions, lacking a groundwork for energy transmission, are easily furnished with this space-based solar power. Simple antennas and receiving stations are all that’s needed.

Meanwhile, the lightweight tiles—which are cheaply manufactured—mean for a more robust space system. The usual wear and tear of long-term spacecraft, such as solar flare or micrometeorite damage, might knock out a tile or two, but wouldn’t be catastrophic to the spacecraft as a whole.

It’s an intriguing concept, and one well worth the investment. With enough interest, and a mobilization of the electronics industry to build the tiles, and the private space industry to transport them to space, it may just be the future of energy.

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