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Why the US Navy wants to return to sextant navigation

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For about a quarter of a century, GPS has embodied a real revolution in geolocation. Nevertheless, it is exposed to hacking, which prompts the United States Navy to consider reverting to an older method: the sextant.

The efficient GPS, but not secure enough

Today, many areas use the Global Positioning System (GPS) to find your way. Let us quote the various armies, maritime transport, and of course all the people having a GPS on board in their vehicle. Let us mention above all the democratization of this technology within the populations, using GPS chips that all smartphones contain today. This inexpensive and easy-to-use geolocation system first appeared in the United States in 1973 for military purposes. In 1995, it became global and fully operational with its 24 satellite system.

Only there you have it, the United States Army think about getting rid of it, as explained Popular mechanics in an article from April 25, 2021. Despite its many qualities, GPS is nevertheless quite easy to hack. However, who says piracy also says surveillance, jamming and sabotage. So indeed, a simple individual does not risk anything by performing a search on Google Maps at home. On the other hand, for the army, the risks are much greater. One case in particular is the perfect example. In 2018, Finland and Norway blamed Russia for disrupting a NATO exercise by jamming the GPS of their armies.

Credits: Wikipedia

A technological step back

The US Navy uses encrypted and secure GPS signals. However, there is no such thing as zero risk and the Defense Department is thinking of a safer way. In reality, the solution mentioned is synonymous with a step backwards in terms of technology. Indeed, it is a question of using the sextant, invented in the first half of the 18th century. Before the invention of GPS, this instrument allowed sailors to orient themselves by calculating the position of stars in the sky according to the time and date. This technique made it possible to determine their position anywhere on Earth.

The Pentagon’s goal is to create modern sextants allowing this kind of information to be analyzed automatically. In the end, it would be a question of obtaining a precision equal to that of the GPS. Moreover, these modern sextants would use infrared signals rather than natural light. This would then provide the means to detect the position of the stars. even during the day.

Promising first results

However, this type of device could experience some difficulties. Indeed, the calculation of the angular distance between two points requires alignment specific. However, this represents an obstacle for infrared instruments because of the strong reflections appearing on the horizon. However, this problem could be solved by relying on artificial satellites rather than natural stars and thus dispense with the horizon line.

Modern sextants could then take the form of simple sensors on board ships of different sizes, but also not soldiers. For the moment, the first results of the development of this type of device bear witness to a accuracy of about 20 m in several tens of seconds. If this precision is better than that of the first GPS, it is still insufficient according to the researchers.


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