Using a navigation system in your car is something we are very used to today.
A few decades in the future one challenge might be how to navigate in space. Nowadays space missions use use a combination of technologies to triangulate their location - these include a pre-determined orbit, radio signals sent from the craft to Earth-based tracking stations, as well as optical information from on-board cameras that look at the local environment.
A problem of radio-based measurements is that it offers only a very low angular resolution. To magnify the problem the further away the craft is, the less accurate will also be the distance measurement.
3 weeks ago, china launched a pulsar navigation satellite trying to test a concept from the 1970s.
The idea is to use pulsars (highly magnetized, rapidly rotating neutron stars that emit "pulses" of broadband electromagnetic radiation at very regular intervals) to determine a position.
There are two ways how to use the signals of pulsars:
1. Delta- Correction:
Using an on-board atomic clock and comparing the difference of a received x-ray pulse of a pulsar to an expected time of arrival. In combination with an initial estimated spacecraft position from ground-tracking, a more precise position of the craft can be determined
2. Absolute Navigation
Eliminating the need for a communication link to the earth, this works similar to a navigation system in a car. Measuring to at least 4 pulsars at the same time we can calculate a 3D-Position.
A simulation of the accuracy indicates that a spacecraft close to Neptune (the farthest known planet from the Sun in the Solar System, approx. 4300 Million Kilometers from the Earth) could determine its position up to 30 km, using only 4 pulsars.