_One of the satellite communications systems that has been proposed
would make use of stationary synchronous satellites. These would be
precisely located above the earth’s equator in orbits 22,300 miles high,
where they would circle the earth once every 24 hours, and thus appear
to remain stationary over a point on the earth. There are several
advantages to this type of system—the most important being that we would
need only three satellites for communications between almost all the
inhabited regions of the earth._
_On the other hand, there are several problems in establishing a
synchronous system. Just getting the satellites into exactly the right
places and keeping them in position is a formidable one. We also have
something of a mystery to contend with, because of the tremendous
distances that would be involved. Although we can communicate at speeds
close to that of light—186,000 miles per second—we cannot go any faster
than that. You might think that 186,000 miles a second was fast enough
for us, and most of the time it is. However, if you send signals 22,300
miles up into the sky, transmit them back to earth, perhaps send them up
again to a second satellite, and finally bring them 22,300 miles back
down to earth, even the speed of light may not be fast enough. The delay
will be only about a second or so, but it may—for some kinds of
communications—be long enough to cause trouble. How much trouble, we
don’t yet know._
_For one-way signals such as television, a transmission delay of about
one second obviously makes little or no difference. But for two-way
conversations on the telephone, where there is rapid back-and-forth
talking, even this tiny amount of time delay may be a problem. And then
again, it may not be. There have been a lot of experiments to find out
something about this delay problem, and these have given us a lot of
different answers. Work is still going on, and there is still much to
find out. In this chapter, we tell you about one small, early
experiment. Its results were not conclusive, but they should give you
one example of how to set up and carry out a typical experimental study
on human behavior._
[Illustration: _Typical circular satellite orbit: r is distance from
center of earth to satellite; R is radius of earth._]