Sentinel-6 Orbit Determination at the Copernicus POD Service

The Copernicus POD (Precise Orbit Determination) Service is a consortium responsible for providing orbit products and auxiliary data files from the Copernicus Sentinel-1, -2, -3, and -6 missions to the corresponding Payload Data Ground Segment (PDGS) processing chains at ESA and EUMETSAT. Products and data are also made available to external users through the ESA Copernicus Open Access Hub.

Sentinel-6 Michael Freilich launched in November 2020 is the newest satellite in the Copernicus POD Service operations. A near real-time orbit product computed based on GNSS data is delivered to EUMETSAT, acting as backup the DORIS DIODE aboard. For the first time, a combined GPS and Galileo receiver is used for POD. In addition, the satellite is equipped with a DORIS receiver and a Laser Retro Reflector for Satellite Laser Ranging (SLR). Additional GPS observations usable for POD are delivered from the POD antenna of the GNSS-RO (radio occultation) instrument. All these observations allow for various cross-comparisons between orbits from the different observation techniques and instruments. The quarterly and yearly Regular Service Reviews include validation of post-processed Sentinel-6 orbit solutions from various members of the Copernicus POD Quality Working Group (QWG).  

This contribution focuses on post-processed POD based on the combined GPS & Galileo receiver and validation with SLR done at the Copernicus POD Service. Precise orbits may be derived as single-system or combined solutions. Integer ambiguity resolution is a key technique to obtain highest accuracy orbits.

Precise orbit determination results from GPS-only, Galileo-only and combined GPS & Galileo observations with resolved integer ambiguities are presented. Cross-comparison between the different solutions, SLR validation, and comparison to other orbit solutions provided by members of the Copernicus POD QWG are shown and analysed.