Precise orbit and baseline determination for maneuvering low earth orbiters

Abstract

Orbital maneuvers are usually performed as needed for low earth orbiters to maintain a predefined trajectory or formation-flying configuration. To avoid unexpected discontinuities and to connect pre-and postmaneuver arcs with a minimal set of parameters, a maneuver has to be considered in the routine GPS-based orbit determinations. We propose a maneuver handling method in a reduced-dynamic scheme. With the proper thrust modeling and numerical integration strategy, the effects caused by orbital maneuver can be largely eliminated. The performance for both single-satellite precise orbit determination (POD) and inter-satellite precise baseline determination (PBD) is demonstrated using selected data sets from the Gravity Recovery and Climate Experiment (GRACE) mission. For the POD results, the orbit determination residuals indicate that the orbit with maneuver modeling is well fit to the GPS observations. The external orbit validation shows that the GRACE-B orbits obtained from our approach match the DLR reference orbits better than 3 cm (3D RMS), which is comparable to the result of the maneuver-free GRACE-A satellite. For the PBD results, on average 87 % of double-difference phase ambiguities can be resolved to integers and an RMS of the K-band ranging system residuals of better than 0.7 mm can be achieved, even though the orbital maneuver was performed on the spacecraft. Furthermore, the actual maneuver performance derived from the POD and PBD results provides rigorous feedback on the thruster system, which is not only beneficial for current maneuver assessment but also for future maneuver plans.

Accurate and Rapid Broadcast Ephemerides for Beidou-Maneuvered Satellites

“…As analyzed in the last subsection, the partial derivatives of (r, . r) with respect to the thrust parameters are not zero since the start of maneuver, and the measurements observed since then will contribute to the estimation of thrust parameters [26]. Meanwhile, to better estimate other unknown parameters, the orbit should be determined in a long arc and measurements before maneuvering should also be taken into account.…”

Distributed multi‐GNSS timing and localization for nanosatellites

“…Traditional methods of integer ambiguity resolution (IAR), such as the least‐squares ambiguity decorrelation adjustment (LAMBDA) method, require an intensive search algorithm because of the integer constraint of the ambiguities . This process is computationally expensive without a guarantee of correctly fixing the values, which could lead to severe degradation of the navigation solution . One method to aid in fixing these values is to extend the range of GNSS signals being processed by the navigation system.…”

Distributed Multi-GNSS Timing and Localization for Nanosatellites

“…Traditional methods of Integer Ambiguity Resolution (IAR), such as the Least-Squares Ambiguity Decorrelation Adjustment (LAMBDA) method, require an intensive search algorithm due to the integer constraint of the ambiguities. This process is computationally expensive without a guarantee of correctly fixing the values, which could lead to severe degradation of the navigation solution [18]. One method to aid in fixing these values is to extend the range of GNSS signals being processed by the navigation system.…”