GPS is great for finding location on Earth. Unfortunately though, it can’t pinpoint the location of objects further off in our Solar System and beyond. Today, Bartolomé Coll and his colleagues at the Observatoire de Paris in France have proposed a ‘GPS’ system a little more universal in nature.
Theoretically capable of pinpointing any location in the galaxy to within a meter, the system relies on the signals emitted by four pulsars (pulsars are rotating astronomical objects which periodically emit light-time signals). The four pulsars–0751+1807 (3.5ms), 2322+2057 (4.8ms), 0711-6830 (5.5ms) and 1518+0205B (7.9ms)–were specifically chosen as the so-called ’satellites’ because they have only milliseconds between emitted signals and basically form a tetrahedron around our Solar System.
While it really only requires 3 GPS satellites for an accurate positioning on Earth, the sheer scale of a galaxy-wide positioning system means that Einstein’s Theory of Relativity needs to be taken into account. Hence, the four pulsars meet the space and time requirements needed for this to work. Boll then adds in an origin for the coordinate system; that being time 00:00 on January 1, 2001 as the initial time and the Interplanetary Scintillation Array, the Cambridge, UK-based telescope that found the pulsars, as the space or location.
Using this system, Boll says that any interplanetary spacecraft should be able to interpret the pulsar signals as a coordinate position in space to within a few nanoseconds. Converting those nanoseconds into more Earthly GPS speak: a few meters.
If you want to dig through all the technical details, you can check out Coll’s paper in a variety of file formats.
