The navigation satellite is located at an altitude of 20,000 kilometers and can be navigated by receiving signals within its coverage. In the deep space of more than 20,000 kilometers, a brand new navigation system is needed. Astronomers have proposed several possible navigation systems, and the most talked about is pulsar navigation. Pulsars are a kind of neutron stars whose magnetic pole direction can produce radio or X-ray radiation. When the rotation axis does not coincide with the magnetic pole, and the rotation axis sweeps over the earth, pulses will be generated. Some of these pulsars are so stable that they can be compared to the best atomic clocks on earth
these pulsars are also called atomic clocks in the universe. If you can pick up their signals and know their location, you can use these pulsars for interstellar travel.
Factors affecting the rotational stability of pulsars