humanity consumed 13 trillion calories of energy a day. Today we consume
1,500 trillion; although the population has only increased by 14 times, the
energy consumption has increased by 115. In sixteenth century, humans
were confined to the surface of the Earth. They could build towers and climb
mountains, but the sky was reserved for birds, angels and gods. On July 20,
1969, humans landed on the Moon. It was not just a historical achievement,
but an evolutionary and even cosmic undertaking. During the first four billion years of evolution, no living organism had managed to leave the Earth’s
atmosphere, and no one had left a print of a foot or a tentacle on the Moon.
13
Only seventy years after Marconi’s radio invention, humans launched themselves and their satellites into space. By combining measurements of time and
radio signals, satellite technology has given birth to one of the most revolutionary
navigation advances of the modern era: the Global Positioning System (GPS).
It all began that night of October 12, 1957. As soon as Radio Moscow announced
the launch of the first artificial satellite, Sputnik, every US radar station tried to
chase that small steel moon flying a thousand miles above them, hoping to understand where it was and what trajectory it was following.
Americans weren’t the only ones trying to locate it. Even the Soviets themselves were faced for the first time with the problem of understanding where
Sputnik really was. Sputnik was equipped with only a single transmitter emitting
radio waves on two frequencies. To locate it, both sides had to intercept the radio
signal – an unmistakable beep – as the satellite flew over a certain geographical
area. In the days following the launch, scientists at the Applied Physics Laboratory
(APL)
14
in Maryland realized that by measuring the Doppler shift
15
of Sputnik’s
sound as it flew over the US, they could calculate its trajectory. They did so primarily to understand if its behaviour could constitute a danger. But soon, Frank
McClure
16
on the APL team noticed that the situation could be exploited in reverse:
if the trajectory had been known a priori, the position of a receiver on Earth could
13
Harari, Yuval Noah. 2014. Sapiens. A Brief History of Humankind. Harper.
14
Founded in 1942, the Applied Physics Laboratory was created by the federal government to
mobilize the scientific resources of the academic world to support the technological challenges
of World War II, especially in the naval field. For seventy years, the APL and the DoD have
been collaborating mainly in the field of guided missiles and submarine technologies.
15
The Doppler effect is an apparent change in the frequency of an electromagnetic signal perceived by an observer, in motion or in a state of rest, with respect to the source of the wave. It
is the classic sound phenomenon that is heard, for instance, when a train approaches and when
it departs.
16
McClure, Frank. 1958. Satellite Doppler as a Means of Ship Navigation. Laurel, MD:
Memorandum, JHU/APL.
56 GPS: The Stellar Clock
1,500 trillion; although the population has only increased by 14 times, the
energy consumption has increased by 115. In sixteenth century, humans
were confined to the surface of the Earth. They could build towers and climb
mountains, but the sky was reserved for birds, angels and gods. On July 20,
1969, humans landed on the Moon. It was not just a historical achievement,
but an evolutionary and even cosmic undertaking. During the first four billion years of evolution, no living organism had managed to leave the Earth’s
atmosphere, and no one had left a print of a foot or a tentacle on the Moon.
13
Only seventy years after Marconi’s radio invention, humans launched themselves and their satellites into space. By combining measurements of time and
radio signals, satellite technology has given birth to one of the most revolutionary
navigation advances of the modern era: the Global Positioning System (GPS).
It all began that night of October 12, 1957. As soon as Radio Moscow announced
the launch of the first artificial satellite, Sputnik, every US radar station tried to
chase that small steel moon flying a thousand miles above them, hoping to understand where it was and what trajectory it was following.
Americans weren’t the only ones trying to locate it. Even the Soviets themselves were faced for the first time with the problem of understanding where
Sputnik really was. Sputnik was equipped with only a single transmitter emitting
radio waves on two frequencies. To locate it, both sides had to intercept the radio
signal – an unmistakable beep – as the satellite flew over a certain geographical
area. In the days following the launch, scientists at the Applied Physics Laboratory
(APL)
14
in Maryland realized that by measuring the Doppler shift
15
of Sputnik’s
sound as it flew over the US, they could calculate its trajectory. They did so primarily to understand if its behaviour could constitute a danger. But soon, Frank
McClure
16
on the APL team noticed that the situation could be exploited in reverse:
if the trajectory had been known a priori, the position of a receiver on Earth could
13
Harari, Yuval Noah. 2014. Sapiens. A Brief History of Humankind. Harper.
14
Founded in 1942, the Applied Physics Laboratory was created by the federal government to
mobilize the scientific resources of the academic world to support the technological challenges
of World War II, especially in the naval field. For seventy years, the APL and the DoD have
been collaborating mainly in the field of guided missiles and submarine technologies.
15
The Doppler effect is an apparent change in the frequency of an electromagnetic signal perceived by an observer, in motion or in a state of rest, with respect to the source of the wave. It
is the classic sound phenomenon that is heard, for instance, when a train approaches and when
it departs.
16
McClure, Frank. 1958. Satellite Doppler as a Means of Ship Navigation. Laurel, MD:
Memorandum, JHU/APL.
56 GPS: The Stellar Clock