Communications and microwave: Orbit and spectrum congestion; tests for electronic mail; phone by light

Terrestrial and space communications have so crowded the spectrum available to satellites in geosynchronous orbit that saturation is threatened, and a search is under way for solutions to avert the interruption of services. Specialists estimate that unless corrective action is taken, there will be no room for new satellites by 1990, and the existing transmission frequency bands will be cluttered with interference.