The proposed solar power satellite collects solar energy above the earth in geosynchronous orbit, converts it to microwaves, and beams it to a receiver on the ground where it is suitably processed and delivered to the electric transmission system as base-load power. The microwave beam will heat the earth's ionosphere and the responses include electron temperature enhancement, plasma striations from thermal self-focusing, and parametric interactions. These responses are described and the possible impacts of these responses on telecommunications and on the system itself are outlined. The heavy lift vehicles needed to launch into space the materials to be used in constructing solar power satellites emit water and other contaminants that react with the ionized gases in ways to speed up the recombination of ions and electrons. Near the launch trajectory and over a volume centered on the region of rocket engine burn the recombination may be complete. The recombination chemistry is indicated and the impact of this effect on telecommunications discussed. The reference solar power satellite system had a design limit of 23 mw/cm**2 for the power density in the microwave beam based on estimates of a threshold of nonlinear interaction of the radio waves and the ionosphere. Experiments have shown that the limit is too low, and theory now suggests that the threshold is soft. The current consensus is that the limit of 23 mw/cm**2 can be at least doubled, and perhaps more, pending further tests.
