The Global Positioning System (GPS) is great, but what do you do when you’re undersea, underground, inside a building, or in the concrete caverns of a human habitation hive where the radio signals from satellites cannot be received? How about using muons (essentially, a heavier flavour of the electron) generated when cosmic rays strike the Earth’s upper atmosphere as a navigation reference? It sounds crazy, but “muometric” navigation has now been demonstrated. A paper from Nature, “Muometric positioning system (μPS) with cosmic muons as a new underwater and underground positioning technique” [full text at the link], describes laboratory tests and simulation showing the feasibility of such a scheme. Here is the abstract:
Thus far, underwater and underground positioning techniques have been limited to those using classical waves (sound waves, electromagnetic waves or their combination). However, the positioning accuracy is strongly affected by the conditions of media they propagate (temperature, salinity, density, elastic constants, opacity, etc.). In this work, we developed a precise and entirely new three-dimensional positioning technique with cosmic muons. This muonic technique is totally unaffected by the media condition and can be universally implemented anywhere on the globe without a signal transmitter. Results of our laboratory-based experiments and simulations showed that, for example, plate-tectonics-driven seafloor motion and magma-driven seamount deformation can be detected with the μPS.
A paper published in ScienceDirect on 2023-07-21, “First navigation with wireless muometric navigation system (MuWNS) in indoor and underground environments” [full text at the link], presents experimental tests of navigation with muons. The abstract is as follows.
Navigation in indoor and underground environments has been extensively studied to realize automation of home, hospital, office, factory and mining services, and various techniques have been proposed for its implementation. By utilizing the relativistic and penetrative nature of cosmic-ray muons, a completely new wireless navigation technique called wireless muometric navigation system (MuWNS) was developed. This paper shows the results of the world’s first physical demonstration of MuWNS used on the basement floor inside a building to navigate (a person) in an area where global navigation satellite system (GNSS)/global positioning system (GPS) signals cannot reach. The resultant navigation accuracy was comparable or better than the positioning accuracy attainable with single-point GNSS/GPS positioning in urban areas. With further improvements in stability of local clocks used for timing, it is anticipated that MuWNS can be adapted to improve autonomous mobile robot navigation and positioning as well as other underground and underwater practical applications.
