GEO, (Geostationary Earth Orbit) is the special orbit where an object in it, orbiting the Earth, stays exactly above a particular place on the earth surface under it. This means a satellite comunications dish antenna aimed at that place in the sky will always be pointed at that place in GEO.

It also means that a spacerail elevator terminal at GEO will be stationary relative to the rotating earth, thus can have an essentially constant connection with the semisolid structure which is also connected to the earth surface at its lower terminal. 

GEO is 91% up out of the Earth's gravitational well, a great place for major spaceport facilities from which conventional rocket spacecraft can come and go, using vastly less fuel for their interplanetary journeys.

The main hazard at GEO is that it is in a Van Allen Radiation Belt, currently a toxic place to be without shielding. KESTS can cheaply bring passive shielding material for surrounding the living quarters. Electromagnetic shielding research ought to be especially useful for at GEO. Probably more useful will be the sponging effect of large amounts of passive shielding in GEO, permanently soaking up and neutralizing the radiation particles trapped there, thus making the environment as safe as elsewhere up there.

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