Two On A Big Ocean The Story of the First Circumnavigation
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in a Small Sailing Ship


      

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Re: Astronomy and Celestial Navigation

From: Peter MacNeil (no email)
Date: Sun Jun 04 2006 - 17:20:22 EDT

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           The US still has the largest system, however with the
    new Russian and EU systems, the US system won't be the
    only one available. But will your reciever still be able
    to accept the same carrier waves? (and yes each of the
    GPS systems uses the same 24 satellite system, 24
    operational, 3 in standby)
       And the US has shut off Selective Availability, they
    haven't removed it. They could turn it on at any moment
    and shut off Differnetial GPS stations...then you are
    back to 100 metre accuracy.

    > > BTW, does the US military still own the GPS satellites,
    > > or the system has been "privatised", as it happened to
    > > the Internet in the middle 1990-s?
    >
    > The US still owns one system. Russia owns a second, and
    > the EU is in the process of deploying a third. I doubt any
    > will ever be privatized because they are still military
    > assets, even if the public is generously allowed
    > substantial (but not complete) access to them.
    >
    > "It is hard for me to imagine a scenario when the GPS
    > system will be targeted. It has to be a war of two
    > superpowers..."
    >
    > I find it easy to imagine. Satellites can be knocked out
    > very easily once you have launch capability, and all sorts
    > of small players and commercial companies now either HAVE
    > that, or shortly will. I can easily imagine someone with a
    > grudge hiring a private launch of an ostensibly innocent
    > satellite, which in turns releases or becomes a debris
    > field that does massive damages. (The GPS satellites are
    > armored, but how extensive the armor is, is classified.)
    >
    > If China ever decides to take Taiwan, they would be a
    > prime suspect to do this, in order to cripple US Pacific
    > Fleet assets and responses. And they can do it in-house.

          Peter I. MacNeil
    Lieutenant (N)
    Fleet Navigating Officer Course
    Serial 0601
    NOTC VENTURE
     "There can be only one!"


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