It is almost a generation since 1994, when GPS finally relegated celestial navigation to being just an intermittent, time consuming and relatively inaccurate backup method of position fixing. It is true GPS was preceded by the Transit satellite system from 1964 and low frequency Omega from 1971. Both of which had global coverage but receivers were bulky, expensive and far less accurate, reliable, or useful than GPS, so take-up was slow. Read More