Humans have a long history of using celestial navigation to get around. Celestial navigation is any technique that relies on the current position of celestial bodies — usually the Sun or other stars. That was often done with the help of devices like a sextant, which measures the angle between the celestial body on the horizon. Now, a team of students from the Royal College of Art and Imperial College have updated that technique for navigation without the use of satellites or the internet.

Most geolocation and navigation today is done with GPS (Global Positioning System) satellites. That’s accurate and reliable right now, but forces users to rely on satellites that are out of their control. If anything were to happen with those satellites, then everybody in a region would be unable to navigate. The system developed by the college students, called Aweigh, provides self-reliance by using modern technology to provide navigation without any outside resources. Aweigh will keep working if something goes wrong with the GPS satellites, and even if the internet isn’t available.

Aweigh devices are essentially modern open source electronic sextants. They’re built with a Raspberry Pi and a custom-designed PCB that’s outfitted with light sensors. Those sensors are used to determine the current position of the Sun, and work even on cloudy days. The position of the Sun, the position of the horizon, the direction of magnetic north, and the current time of day can be used to calculate the user’s location. The team doesn’t say how precise those calculations are, but they should be enough to provide an approximate location — at least during the day. They plan to continue to work on Aweigh, and hope the community will help them improve the accuracy of the system.