Subatomic particles created by cosmic ray collisions were used to create a “new kind of GPS.” In a new study, University of Tokyo scientists have shown how these high-energy particles can be used to navigate underground chambers deep beneath a building. This navigation would not be possible using the conventional Global Positioning System (GPS).
This ability, the first of its kind, is made possible by muons, high-energy particles produced by cosmic rays striking atoms in Earth’s atmosphere. Muons “fall” to Earth in a steady downpour of about 10,000 square meters per minute and move at the same speed regardless of whether they are in air, water, or rock.
These attributes were previously used to study the depths of ancient Egyptian pyramids and volcanoes. Now, in a world first, scientists have used muons to navigate underground.
“Cosmic ray muons fall evenly to Earth and always move at the same speed regardless of what material they pass through, penetrating even miles of rock,” study author Professor Hiroyuki Tanaka of Muographix at the University of Tokyo said in a statement. “Using muons, we have developed a new type of GPS that we call a muometric positioning system (muPS) that works underground, indoors, and under water.”
Traditional GPS devices use data from satellites to locate a specific point on Earth in a process called trilateration. In simple terms, a GPS device works by measuring the distance to satellite A, satellite B, and more. This new method works on a similar principle, but uses muon-detection sensors instead of low-Earth-orbiting satellites as a reference point.
The researchers conducted an experiment in which a reference station that detects four muons was placed on the sixth floor of a building while a person took a receiver detector to the basement. As the person walked up and down the corridor of the basement, he was able to follow his movements with relatively good accuracy.
Tanaka said, “The current accuracy of MuWNS is between 2 meters and 25 meters, and the range is up to 100 meters depending on the depth and speed of the person walking. This is as good as single-point GPS positioning above ground in urban areas,” he said. “But it’s still far from a practical level. People need one-metre accuracy, and the key to that is time synchronization.”
The researchers hope that accuracy can be improved using chip-scale atomic clocks (CSACs), although they acknowledge that they are currently too expensive. However, they predict that as this technology becomes cheaper and more accessible, muometric wireless navigation systems may eventually become a common feature in smartphones.
The study was published in iScience.
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