Success Has Many Fathers - GPS Declassified: From Smart Bombs to Smartphones - page 38

Three tracking stations demonstrated the ability to track Pioneer 4 to the
great distance: Jodrell Bank in England with its 150-foot diameter antenna,
the Jet Propulsion Laboratory ( jpl) at Goldstone Lake, California with its
85-foot antenna, and a temporary setup at the ge Research Laboratory, Sche-
nectady, with an 18-foot diameter parabolic antenna. . . . There was immense
media interest in our effort. Pioneer 4 was the first object to escape Earth's
gravity. We were besieged with phone calls at all hours of the day and night.
With our small antenna we were seen as David against Goliath. On the morn-
ing of 6 March, the signal was weak and intermittent. Finally, search as we
could, we could no longer get a lock on it. In mid-morning, a reporter called
and said, “jpl announced that they lost a signal. Do you still have it?” “No.”
“When did you lose it?” “I don't know exactly?” “Can we say that at 10:25
you said that you lost the signal?” It was 10:25. “Yeah.” By 10:27 the whole
world was informed that ge had tracked the space probe farther than jpl. I
went to a newspaper office and asked them to publish a disclaimer. They
were not interested. jpl was not pleased. 3
In 1959 Anderson discussed the use of range (distance) and range difference
measurements for satellite navigation systems with Navy captain Alton W.
Moody of nasa, who was president of the Institute of Navigation from 1959
to 1960. Range measurement computes the distance a radio wave travels from
a satellite to a receiver, basing its calculations on the travel time, since radio
waves move at the speed of light. Seventeenth-century astronomers noticed
that observations of the Jovian moons were affected by whether the earth was
on the same side of the sun as Jupiter or on the opposite side. This phenome-
non showed that light travels at a finite speed. Nineteenth-century physicists
hypothesized that it travels through a medium called ether. This reflected a
philosophic aversion to the concept that space is largely a vacuum. Physicist
Albert Michelson and chemist Edward Morely proved that the speed of light
is a constant in a famous series of experiments in 1887. This disproof of the
ether theory helped inspire Albert Einstein to formulate the special theory of
relativity. Light travels at 186,282 miles per second. Consequently, the receiver
is 18,628 miles from the satellite if the signal takes a tenth of a second to travel
from it. Thus, one knows that the receiver is somewhere on the surface of a
sphere 18,628 miles from the satellite.
Anderson submitted a satellite navigation proposal in January 1963 to nasa,
which awarded him a contract. He proposed two modes of operation: an active