The Blue dot – How positioning technology changed the world
“We succeeded in taking that picture from deep space, and, if you look at it, you see a pale blue dot. That’s here. That’s home. That’s us.”
Carl Sagan’s famous speech was inspired by a photograph of planet earth, taken by Voyager 1 in 1990. Surrounded by deep black space a 0.12 pixel point of light appears, caught in scattered rays from the sun.
This picture provided a powerful shift in perspective at a philosophical level by showing our home in relation to the vastness of space around us. However, at planetary and more local levels, finding ourselves is crucial to understanding the world, navigating it effectively making informed decisions.
Over the years, we have relied on different reference points to position ourselves. In this article we’re going to chart the course of these systems and technologies over the last 2,000 years to the present day and beyond.
A look around
The first reference points that come to mind are the visual sights around us: Natural landmarks like mountains, lakes and rivers or man-made features like towers, buildings and roads gives us an idea of where we are.
For navigation, two tools – a magnetic compass and a map – are used to determine a position by referencing visual fixed points.
This method is known as pilotage and is more than 2,000 years old. The compass provides bearings to landmarks from the current point of view. With at least two reference points, the meeting of the bearing lines marks the location on the map.
Because natural landmarks hardly change and our maps are getting more and more accurate, this way of positioning can still be used today. But of course it can only be applied under certain conditions:
When you are travelling the open seas, there just aren’t enough physical landmarks around to get a visual reference. That is why sailors navigating in the Mediterranean were the first to make use of the stars for orientation.
Shoot for the stars
The first written records of celestial navigation go back to Homer’s Odyssey, where the goddess Calypso told Odysseus to keep “the Bear” — the constellation Ursa Major — on his left-hand side to find his way.
Through the centuries, we developed better tools to connect the position of celestial bodies to our own location:
The nautical almanac and a marine chronometer are used to compute the subpoint on earth a star is over. The sextant is used to measure its angle to the horizon, which is directly related to the distance to its observer.
By mastering these tools and techniques, long distant journeys were made more predictable and safer than Homer’s Odyssey.
A matter of life and dead reckoning
In the scenario that no points of references can be seen, with the coast out of sights and clouds obscuring the night sky, even celestial navigation fails. That’s when a carefully kept log book, a marine compass and clock can save lives. A technology known as ‘dead reckoning’ makes use of the previously determined position or so-called ‘fix’ and the information about the vessel’s movement to make an educated guess about the new position.
For our nocturnal ship on the ocean that means keeping an accurate log book with latitude and longitude information from the key places where pilotage or celestial navigation is possible. By measuring the speed, time and course of travel it’s possible to estimate its current distance from the last fix. As one of the primary navigation methods dead reckoning has also been used for both air and land navigation.
The basic science behind which is still implied in the modern-day navigation, but the process has gone from manual computation to computer automation. For example, a modern Pedestrian Dead Reckoning system (PDR) can help locating handheld mobile devices. The device’s inertial navigation system uses live data from the built-in motion and rotation sensors to estimates its deviance from the previous position.
With nowadays satellite technology, there also came an easier way to get location fixes from the sky: A global positioning system.
GPS – the positioning revolution
GPS has its origins in the mid 1960s when the United States Navy conducted satellite navigation experiments to track submarines. It grew into a global network with 33 satellites free for everyone to use and to pinpoint the location of mobile devices.
New wayfinding and navigation tools made use of this network and revolutionised all forms of travel from marine operations up to automotive travel and pedestrian wayfinding with a live blue dot on the map.
But while GPS is very accurate in open areas, street canyons with tall buildings result in poor signal reception and a less accurate positioning. Indoors it becomes just about useless.
Plus, even the most advanced satellite technology can be prone to error, systems can get hacked and GPS can be jammed. As a response to this risk celestial navigation was reinstated in Naval Academies in 2011.
To address these issues, particularly in indoor environments where GPS signal is most problematic, scientists, engineers and cartographers are considering new ways to provide accurate and reliable positioning.
A sensor fusion future?
Positioning technology is still evolving. In an urban society, we spend most of our lives indoors and GPS can’t reach us there. However, like our forebears we can use the signals our rapidly changing environment generates to help us understand where we are.
Radio frequencies like Wi-Fi and Bluetooth, which have become as much part of our surroundings as any physical landmarks, can be combined with data generated by our personal mobile devices to create an indoor positioning fix.
Developments to improve positioning technology multiple environments will create new opportunities. It can help to make our daily life and work in complex buildings simpler, and fundamentally change our experience of built environments in the same way that other positioning technologies have shaped our experience of outdoor places so far.