[Image: From The Hunt For Red October, via Quora].

There?s a throwaway line in The Hunt For Red October where a submarine navigator jokes, ?Give me a stopwatch and a map, and I?ll fly the Alps in a plane with no windows.? I was reminded of that comment by reports of a new atomic clock that will allegedly enable ?futuristic navigation schemes?:?Every single spacecraft exploring deep space today relies on navigation that?s performed back here at Earth,? said [Jill] Seubert, who?s based at NASA?s Jet Propulsion Laboratory in Pasadena, Calif. Earth-based antennas send signals to spacecraft, which the spacecraft echo back. By measuring a signal?s round-trip time within a billionth of a second, ground-based atomic clocks in the Deep Space Network help pinpoint the spacecraft?s location.
With the new Deep Space Atomic Clock, ?we can transition to what we call one-way tracking,? Seubert said. A spaceship would use such a clock onboard to measure the time it takes for a tracking signal to arrive from Earth, without having to send that signal back for measurement with ground-based atomic clocks. That would allow a spacecraft to judge its own trajectory.One might say that the ship is navigating time as much as it is traveling through space?steering through the time between things rather than simply following the lines that connect one celestial object to another.

The general problem of ship orientation and navigation in deep space is a fascinating one, and it has led to ideas li...