Detecting dark matter using GPS satellites

The GPS as a direct dark matter particle detector. Neat !

Perhaps dark matter could be found via its interaction with atomic clocks. The clocks, which measure time based on the quantum properties of atoms, are the most precise instruments ever built, Derevianko says. They are so accurate that they wouldn’t gain or lose more than a single second over the age of the universe. Dark matter passing through them, however, should affect the atomic processes on which they are based, throwing them off ever so slightly.

“The electrons and the nucleus ‘feel’ the effect of the dark matter, and this can change their properties temporarily,” says Benjamin Roberts, an Australian postdoctoral researcher working with Derevianko in Reno. “For example, the dark matter might make the electrons in the atom attracted to the nucleus slightly more (or less) strongly. Another way to say it is that the dark matter field may speed up or slow down the electrons (very slightly and only for a few seconds).”

Furthermore, the Earth is surrounded by an entire network of atomic clocks. They are carried by satellites in the global positioning system network, which uses them to send out the hyper-accurate timing signals that make GPS work. Over all, 32 satellites form a halo of instruments around the planet, spanning a sphere 50,000 kilometres wide. That’s enough that even though dark matter is expected to be reaching the Earth at speeds in the order of 300 kilometres per second, it would still take three minutes to cross the entire cloud of GPS satellites. Rippling glitches in their time signals could thus be used to detect sheets of passing dark matter, as long as they are large and dense enough.

https://cosmosmagazine.com/space/gps-satellites-the-largest-dark-matter-detector-ever-built