Abstract: In order to realize autonomous and continuous navigation information outputs, an integrated navigation system based on celestial navigation and GPS navigation is proposed. Since the celestial navigation method based on star\|earth angle observation is vitiated due to severely dynamics change around perigee, the navigation accuracy declines seriously. Moreover, the GPS navigation method with high estimate accuracy in the near\|earth space can not cover the apogee due to the altitude limitation of GPS satellites. In this paper, both celestial and GPS navigation outputs are fused by the UKF filter. When the satellite is near the perigee, the GPS navigation is introduced to achieve accurate navigation. At the same time, the estimate covariance is revised through information fusion to improve the celestial navigation estimate. When the satellite is near the apogee, the celestial navigation method plays the major role in navigation process. Simulation results show that the proposed integrated navigation method can overcome the disadvantages of the two navigation methods, and achieve autonomous and continuous navigation information outputs during on\|orbit operation. The navigation accuracy is improved by 61.2%～82.7% compared with the only celestial navigation method.

Key words: Highly elliptical orbit, Celestial navigation, GPS, Information fusion, InteGrated navigation