Humans are extremely curious creatures. We are made to walk on land and we can swim for short periods of time, but we want to go deeper. However, navigation under water is a big challenge. Now scientists from the University of Queensland took inspiration from some marine animals to develop a polarization-based underwater geolocation technique.
Scientists took a look at how various animals, such as the mantis shrimp and cephalopods (squid, cuttlefish and octopus), locate themselves under water. These creatures use the principle of polarization. It would be very useful for people as well, because our normal navigation methods do not work underwater. GPS stops working at the depth of around 20 cm, which is clearly not enough. Furthermore, visibility is often very limited – the deeper you go, the less light you see. But the problem is that humans cannot perceive polarised light without the help of special lenses and that is what scientists had to do.
A team of researchers analysed the basic geolocation methods used by some marine animals. They broke down the core principle and used it to create a technique using imaging equipment that was sensitive to polarising light. This equipment uses polarisation sensors that determine the sun’s position in the sky based on patterns of light underwater. The result is a technique which is far superior and far more accurate than pretty much everything available today. For example, currently submarines use satellite-based GPS when they are close to the surface. Then they go deeper carefully registering their course and movement. It is basically dead reckoning, which reduces accuracy the longer the submarine stays underwater.
Submarines need to resurface periodically to restore the GPS signal in order to maintain their accuracy. This is an inconvenience in the military world, but in the world of science it means that research results are simply not as accurate as they should be. Dr Samuel Powell, one of the authors of the study, said: “Using polarisation sensors, our method would allow for real-time geolocalisation underwater with more accurate long-distance results, without the need to resurface periodically”. In fact, this technique allows accurate geolocation at depths up to 200m below the ocean’s surface.
This may look like a small achievement, but it really is significant. While humanity is eyeing deep space exploration, a lot remains to be discovered about our oceans and this may be one of the tools we needed.
Source: University of Queensland