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    Re: Cosmic Ray Muons Not GPS Satellites
    From: Peter Monta
    Date: 2021 Nov 27, 20:34 +0000
    Thanks for mentioning this.  It's an interesting scheme.

    The press release really doesn't describe how the system works.  Are they detecting Cerenkov light?  Are they detecting multiple muons from the same cosmic-ray shower dispersed over some cone?  No, it turns out they're doing time-of-flight of a single muon passing through two detectors, one with known position.  That generates a sphere-of-position constraint, and then multiple reference stations complete the scheme.

    Even with large (~10 square meter) scintillators, the Nature article is talking days of integration time.  That's fine for seamount monitoring, but it seems like a stretch for a submarine, for example.  With inertial aiding, maybe a multi-day integration could provide some value, and the required cable (!) between submarine and reference detector could perhaps be eliminated with a pseudorange and a good clock on the sub.

    Great, but if improved above-ground polar coverage is your goal, you'd do far better with LEO signals of opportunity (from Starlink or OneWeb or Iridium), or eventually dedicated LEO navigation smallsat constallations bootstrapping from the overhead GNSS.  Or some high-inclination GPS birds, for heaven's sake, but that's just crazy talk, right?

    Cheers,
    Peter

       
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