Impact of satellite yaw attitude regime on in-flight calibration of low-Earth orbiter GPS antenna phase center

Aurore E. Sibois (Jet Propulsion Laboratory, California Institute of Technology, United States)

CoAuthors

Shailen D. Desai (Jet Propulsion Laboratory, California Institute of Technology, United States)

Event: 2019 Ocean Surface Topography Science Team Meeting

Session: Precision Orbit Determination

Presentation type: Type Oral

We investigate the sensitivity of the in-flight calibration of the Global Positioning System (GPS) antenna phase center onboard low-Earth orbiters (LEOs) to the spacecraft’s yaw attitude regime. The precise determination of the phase center offset (PCO) and variations (PCV) of the GPS antenna onboard LEOs is critical to achieve high-precision GPS-based orbit determination (POD) of these satellites. Changes in the geometry between the GPS transmitter and LEO receiver antennas are beneficial to the receiver antenna calibration by increasing the observability of its PCO. Knowledge of the LEO attitude is therefore essential and can be used to tune the estimation strategy of the LEO PCO/PCV.

We study the case of two LEOs with different yaw attitude behaviors: Jason-3 and Sentinel-3A. Jason-3 transitions between a yaw-steering mode characterized by large (e.g., +/- 120 degrees) sinusoidal yaw angle variations and a yaw-fixed mode, as well as yaw-flips where the satellite transitions from flying ‘forward’ to flying ‘backward’. The transitions between those attitude regimes are dictated by the variation of the satellite’s beta prime angle. The Sentinel-3 satellites on the other hand are designed to always fly in yaw-steering mode with variations of very low (e.g.,+/- 6 degrees) amplitude. For both spacecraft, we evaluate the impact of each attitude mode on the estimated values of the Along-track, Cross-track and Radial coordinates of the PCO and their associated formal errors. We show that yaw flip transitions dramatically decrease the uncertainties on all 3 coordinates and that the amplitude of change in the yaw angle in yaw-steering mode is highly correlated with the observability of the Cross-track-offset but has little influence on the determination of the Along-track and Radial offsets. We also analyze the impact of using PCO/PCV estimates derived from in-flight tracking data covering different time spans characterized by the attitude regime of the satellite of interest on the quality of the orbit determination. Based on these results, we conclude on the potential advantages of large and rapid changes in yaw attitude for in-orbit calibration and validation post-launch, with potential application to Sentinel-6 and SWOT.

 

Oral presentation show times:

Room Start Date End Date
The Monroe Hub Tue, Oct 22 2019,11:45 Tue, Oct 22 2019,12:00
Aurore E. Sibois
Jet Propulsion Laboratory, California Institute of Technology
United States
aurore.e.sibois@jpl.nasa.gov