The terrestrial solar energy conversion methods capable of generating power continuously are reviewed, and the rationale for solar energy conversion in geosynchronous orbit is outlined. The principles of the concept of solar power satellites (SPS) are presented, and the technology options for converting solar energy in space, transmitting microwave power, and converting it on Earth into electricity, are summarized. The development of the design concept of the SPS, based on solar thermal and photovoltaic conversion, is examined, and salient characteristics are provided. The details of microwave power generation, beam transmission, and conversion to DC at the receiving antenna on Earth are discussed. The requirements for a space transportation system, orbital construction and assembly, maintenance and operations are reviewed. The environmental impacts of SPS operation, such as stratospheric emission by space vehicles and atmospheric attenuation and scattering, ionospheric interactions, and biological effects of the microwave beam, are highlighted. Economic and social issues are considered, and the potential contribution of the SPS to meet future energy demands is projected.
