Analysis of Precise Orbit Determination for Maneuvering HY2C and HY2D Satellites Using DORIS/RINEX Data

Accurate Low Earth Orbit satellite (LEO) orbits are essential for many applications, such as for assessing the change in current global mean sea level, or solving the ground coordinates and velocities of tracking system networks such as the DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite). Maneuvers are required for any remote sensing satellite to maintain the reference orbit. The presence of orbit maneuvers poses a challenge for Precise Orbit Determination (POD). At present, most maneuver analysis is conducted using the reduced-dynamic POD approach thus making it impossible to separate specific forcing effects, such as atmospheric drag or maneuver acceleration, from the generic empirical acceleration parameters used in the approach to absorb remaining errors. Therefore, this paper adopts the dynamic model method to better evaluate maneuver accelerations estimated from HY2C and HY2D DORIS/RINEX data. And, we focus on the determination of highly accurate HY2C and HY2D orbits over spans which can include maneuver events. In the course of this study, a maneuver model strategy is developed, and we use the DORIS/RINEX data of HY2C and HY2D satellites to validate the method, and to show it is reliable. Our analysis results are: (1) The standard deviations of DORIS residuals for HY2C and HY2D satellites are respectively 0.45 mm/s and 0.43 mm/s, and these residual values have no significant fluctuations and systematic errors. (2) In the case when there are no DORIS tracking data over the maneuver period, extending the period by 30 s to include tracking will improve orbit accuracy sufficiently to even satisfy altimetry requirements. (3) Based on the developed maneuver model strategy, the radial orbit differences can achieve about 1.70 cm, that can satisfy high precision altimetry requirements of HY2C and HY2D satellites. (4) When the model strategy is used on days containing no orbit maneuvers, the average RMS (root mean square) of radial orbit differences for these days is 1.60 cm, which shows that our maneuver model strategy is also reliable.