X-ray pulsar/Doppler difference integrated navigation for deep space exploration with unstable solar spectrum

To eliminate the effects of unstable solar spectrum on the Doppler velocity measurement, a solar light Doppler difference measurement method is developed. In this method, two Doppler velocities with respect to the Sun and the Mars are measured. And their difference, which does not include the Doppler velocity bias caused by the unstable solar spectrum, is utilized as the navigation measurement. As the novel Doppler difference navigation method cannot work alone due to its accumulative position error, we combine it with the X-ray pulsar navigation method, and propose the X-ray pulsar/Doppler difference integrated navigation for deep space exploration. The simulation results demonstrate that the proposed integrated navigation method is robust to the Doppler velocity measurement bias caused by the instability of the solar spectrum effectively, and keeps the high accuracy of the pulsar/Doppler-integrated navigation system.