NavList:

Many years ago, the NOSS triples, small sets of three satellites operating as a group, were reported to be tracking ships at sea by collecting random radio noise from each vessel and then determining location primarily by signal travel-time delay. The triples were eventually replaced by pairs. The Chinese apparently operate similar clusters of satellites with the same function. They're fun to watch, too, since they traverse the sky in groups.

This "spy stuff" has now gone commercial, and in a few years it may be possible to subscribe to your vessel's position. Rather than navigating actively with a sextant, and instead of receiving the faint, easily-jammed, potentially-spoofed radio signals from the current GPS/GNSS constellations, your position would be determined by a commercial "traffic control." We're not there yet, but soon every vessel at sea that has any radio output will be tracked, and that information will be made available to subscribers. Since I am contemplating a life as a pirate on the high seas (yarrrrgh...), I intend to subscribe. Ha. That may be a problem, but the value for safe navigation is clear, and it also easily translates to other planets and moons. A handful of cubesats in lunar orbit can find anything that "beeps".

An article from The Economist:
https://www.economist.com/science-and-technology/2021/03/17/small-cheap-spy-satellites-mean-theres-no-hiding-place

Frank Reed