In outer space, the sun always shines brightly. No clouds block the solar rays, and there is no nighttime. Solar collectors mounted on an orbiting satellite would thus generate power 24 hours per day, 365 days per year. If this power could be relayed to earth, then the world's energy problems might be solved forever.

Solar power satellites (SPS) were originally proposed as a solution to the oil crises of the 1970s by Czech-American engineer Peter Glaser, then at Arthur D. Little. Glaser imagined 50-square-kilometer arrays of solar cells deployed on satellites orbiting 36,000 kilometers above fixed points along the equator. A satellite at that "geosynchronous" altitude takes 24 hours to orbit the earth and thus remains fixed over the same point on earth all the time.

The idea was elegant. Photovoltaic cells on a satellite would convert sunlight into electrical current, which would, in turn, power an onboard microwave generator. The microwave beam would travel through space and the atmosphere. On the ground, an array of rectifying antennas, or "rectennas," would collect these microwaves and extract electrical power, either for local use or for distribution through conventional utility grids.

The technology, as originally envisioned, posed daunting technical hurdles. Transferring electrical power efficiently from a satellite in geosynchronous orbit would require a transmitting antenna on board the satellite about one kilometer in diameter and a receiving antenna on the ground about 10 kilometers in diameter. A project of this scale boggles the mind; government funding agencies shied away from investing immense sums in a project whose viability was so unclear. NASA and the Department of Energy, which had sponsored preliminary design studies, lost interest in the late 1970s.