Transmit data through the ice to both navigate more calmly in icy waters and map polar zones. This is the aim of the Subzerospace program developed jointly by Kongsberg Discovery, the University of Oslo, the NTNU Technical University, NASA, the Norwegian Polar Institute, Sintef and Mustad Autoline.
At the basis of this project launched in 2021, there is the idea of finding a way to communicate through the ice using acoustic sensors that could autonomously detect and avoid nearby dangers. This would be a big leap forward for navigation in ice which, despite dedicated charts and the trained eye of sailors on the bridge, still represents significant risks.
Researchers and engineers began their field research this summer by visiting the Juvfonne glacier, in the Norwegian Jotunheimen massif. Even in the middle of the summer season, the latter remains very cold and made it possible to test Kongsberg’s sensors, designed for aquatic but certainly not glacial use, in extreme conditions. Scientists dug a 3.5 meter deep hole in the snow. They were able to reach into the ice to place a small installation to send signals and a hole in the ice wall below, both filled with water to allow acoustic connections between the equipment and the ice.
To be able to map thick ice using radio waves or seismic or acoustic technologies, and to communicate wirelessly through thick ice, current equipment must be adapted. It is therefore necessary to be able to define the absorption and diffusion characteristics of waves through this element. Scientists therefore want to be able to develop new communication systems, algorithms and protocols in order to be able to use them in particular for navigation, as well as underwater drones for mapping under and through the ice.
So the scientists sent waves from 200 Hz to 18 kHz to determine the speed and distance of communication through the ice. They worked a lot on the frequency response, reverberation and ambient noise level. They found good results with cNODE and cPAP sensors at a frequency of 10-15 kHz at a distance of 40 meters. They were able to observe that the use of reinforced fiber connections is possible in the icy layer with a mixture of radio frequencies and acoustic communications which extends to approximately 25 km in water and ice.
These promising results, as well as those of another expedition and field tests carried out in the Svalbard archipelago last August, will now be analyzed by the researchers.
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