Development status and performance of the NASA payload for the Sentinel-6 mission (Conference Presentation)

Abstract

The Sentinel-6 (S6) Mission will provide continuity of ocean topography measurements beyond TOPEX-Poseidon (launched in 1992), Jason-1 (2001), OSTM/Jason-2 (2008), and Jason-3 (2016) for determining ocean circulation, climate change and sea level rise. Unlike past Jason missions, S6 will also contribute atmospheric temperature and humidity profile measurement in near real time to support operational weather forecasting. The S6 mission consists of two satellites to be launched approximately 5 years apart to extend measurement continuity for at least another decade. This mission will serve both the operational user community and also enable the continuation of multi-decadal ocean topography measurements for ocean circulation and climate studies. The first S6 satellite is planned to launch by the end of 2020 with a suite of instruments similar to the prior Jason series missions. Sentinel-6 is a cooperative mission with contributions from NASA, NOAA, ESA, and EUMETSAT. The ocean altimetry science payload is similar to the prior Jason missions, including a nadir altimeter, water vapor radiometer and precision orbit determination system instruments. The nadir altimeter is contributed by ESA and EUMETSAT and comprises a new dual-frequency (C and Ku band) synthetic aperture radar (SAR) altimeter (Poseidon-4). The NASA-provided payload is managed and developed by the Jet Propulsion Laboratory (JPL). It consists of the Advanced Microwave Radiometer for Climate (AMR-C) instrument that includes a new on-board absolute Supplemental Calibration Subsystem (SCS). The SCS is a key evolution of the radiometer instrument that will enable a significant improvement in the sea surface height measurement stability. The AMR-C provides the water vapor path delay correction to the ocean height measurement from the Poseidon-4 Radar Altimeter. The AMR-C is further enhanced by an experimental High-Resolution Microwave Radiometer (HRMR) that will demonstrate the capability of high frequency (90, 130, 166 GHz) radiometer channels for extending the wet path delay measurements into the coastal zone with ~5x finer spatial resolution compared with the traditional low-frequency AMR channels. The NASA payload also contains a Laser Retroflector Array (LRA) that supports ground-based laser tracking for precise orbit determination validation. As a secondary mission objective, S6 will also characterize atmospheric temperature and humidity profiles by measuring bending angles of GNSS signals occulted by the Earth’s atmosphere. These measurement products will be ground-processed within three hours of acquisition on board the satellite and made available for ingestion into national weather service models to support weather forecasting capabilities. This measurement is provided by the NASA-provided Global Navigation Satellite System for Radio Occultation (GNSS-RO) instrument. We present a description of the overall mission and focus on the NASA payload architecture, development status and (pre and post) launch expected performances.