REKINDLED HOPE

A meteoric radio path, however, gets the best of three worlds: Its reflection region is almost as high as the ionospheric layer that reflects medium waves (AM band) at night, which is the reason for the 1200-mile range; it uses ultra-short waves, which can accommodate far more frequencies for individual users; and there may even be several paths operating on the same frequency if they do not run in the same direction or if they are far apart. The reason for the last point is that not every meteor trail above the horizon of the two stations is suitable for communication; geometric considerations of the trail orientation limit the usable trails to two comparatively small portions (the "hot spots") of the sky on either side of the link, considerately leaving the rest of the sky to other users on the same frequency.

Such points raised high hopes for this type of communication in the middle 5Os, but they did not materialize. There was not enough demand for one-way (or two-way, but always stop-and-go) communications, and a few years later communications satellites with their thousands of telephone channels were on the drawing boards, if not yet in the sky.

Three factors have now rekindled the hopes of 30 years ago. First, the expanded need for telemetering in remote and inaccessible areas, especially in oil and gas production; and second, the wide use of computers, which do not mind a little stuttering when they talk to each other.

And a third factor has now appeared: reliable communications in networks damaged or disabled by the EMP (electromagnetic pulse) of a nuclear detonation. The air force has been looking into linking radar stations that way, the navy into maintaining contact between ships and their home base, and the Federal Emergency Administration into making its own network survivable through EMP.

Such measures are, of course, strong deterrents against aggression, for nothing deters an aggressor as effectively as the prospect of failure.

And nothing drives the ESPS (Ex-Scientists for Preemptive Surrender) as wild as counter-measures that deter without endangering a single life -- High Frontier and emergency hospital beds are other examples. It threatens their one remaining ability: to frighten the pants off their listeners.