Navigation via cosmic ray muons could supplement GPS in high latitudes, as well as working underwater and underground.
The US Office of Naval Research聽(ONR) has awarded a contract to UK company Geoptic Infrastructure Investigations to demonstrate navigation in the Arctic where GPS coverage is poor due to positioning of GPS satellites run by the US military, which are mostly at lower latitudes.
The firm鈥檚 Muometric Positioning System (muPS) uses聽muons made by cosmic rays聽instead of the radio signals from satellites used by GPS. When a high-energy cosmic ray strikes the upper atmosphere, a shower of聽muons rains down. These pass through solid matter, but can be detected by scintillation counters. On average, 鈥渙ne muon will pass through your thumbnail every minute鈥�, says at Geoptic.
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MuPS has a set of reference counters that pick up muon showers in a pre-defined locale. Aided by precise atomic clocks, they triangulate the source and time of each shower. This allows a聽mobile counter to locate itself by聽comparing the time difference for the same shower.
The method requires multiple聽muon showers to get聽a聽fix on the location, but lab tests have shown how accurate it聽can聽be. Just 10聽muon events are聽enough to locate a point with an聽accuracy of聽60聽millimetres, says at Geoptic. Further聽measurements increase that to聽10聽millimetres or less.
The proof-of-principle experiment will use detectors that聽are 1 square metre in size, plus atomic clocks accurate to within a 10聽billionth of a second. These cost tens of thousands of dollars, but are quickly becoming cheaper.
The real challenge is that the ONR wants a demonstration beneath the surface of a frozen lake in Finland to take place before聽August 2022. 鈥淭he average temperature is around -20掳C, so we鈥檒l be using [snowmobiles] for transport and cutting holes in the ice with chainsaws to deploy the聽system,鈥� says Steer.
The aim is to show that muPS works in difficult field conditions. Once the receiver has been calibrated with the reference counters, it can continue to locate聽itself while underwater even聽if it only communicates with聽the counters intermittently.
MuPS could provide underwater navigation for uncrewed vehicles and submarines. Precise submarine navigation is a major issue: in October, the nuclear submarine USS Connecticut was聽damaged by a collision with聽an underwater mountain.
The developers say that because muons can also travel through rock, they have had interest from the US Army in a portable version for navigating tunnels.
鈥淭his is the first time I鈥檝e heard of [cosmic rays] being used for navigation, but there are a lot of new applications ranging from mineral prospecting to inspecting industrial infrastructure and detecting nuclear material,鈥� says at the University of聽Glasgow in the UK.
