Satellite navigation in the 18th century

http://www.lowtechmagazine.com/2008/01/satellite-nav-1.html#more


Man has navigated across the globe by means of satellites for thousands of years – however, until the mid twentieth century, these were not GPS-satellites, but stars. In reality, the sun and the stars aren’t satellites of the Earth, but celestial navigation is based on a precopernican world view (the earth was believed to be the centre of the universe). This may sound a little outdated, but this system was perfected to such an extent that in the second half of the eighteenth century it was almost as accurate as the present-day GPS. Moreover, it was much more robust. (Picture sextant : Peter Ifland)

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"Should anything go wrong with the GPS-satellites, we would be catapulted back in time: not to the eighteenth century, but to antiquity."

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Satellite navigation is becoming ever more important. In just ten years, navigation devices guided by GPS have become an indispensable instrument in automobiles, and now the technology is conquering the mobile telephone. Satellites are also replacing radar technology for the navigation of ships, trains, planes, spaceships, submarines, tanks and (the reason why the system was originally designed) bombs.

No matter how vital satellite navigation seems to be these days, the thirty American controlled GPS-satellites satellites were only launched into space from 1989 to 1994. Russia also has its own navigation system (that became redundant) and China has put forward developmental schemes for their now relatively limited Beidou system. For some years now, Europe has been trying to scrape together enough money for the building of its own system, Galileo.

Until the year 2000, the GPS-signal was deliberately downgraded to an accuracy of 100 metres by the American defence. Since then, the commercial system is accurate to a distance of 10 to 30 metres (horizontal) and 20 to 60 metres (vertical). The US military forces now boast an accuracy range of less than 3 metres, which in combination with other techniques can be augmented to less than 1 centimetre.


Craftsmanship

The GPS-system instantaneously informs users of their three-dimensional position on earth: in terms of degree of longitude (the position relative to the prime meridian in Greenwich), degree of latitude (the position relative to the equator) and altitude (the position relative to sea-level). To put it bluntly: today, even an idiot can determine his or her position on earth by pressing a button. Some centuries ago, it was possible to achieve a determination of your position on Earth which was almost as accurate as with GPS – but only with time, craftsmanship and significantly more complexity.

I was just talking about how GPS with cell phones could revolutionize public transit in the case of an oil crunch, but of course that makes transportation built on the same house of cards. I think we need to diversify energy sources and positioning systems. With the exception of ships and things out in the middle of nowhere, it can be done differently. (It may even be doable in a different way for ships if you think about it)