Inside SpaceX's Payload Processing Facility at Vandenberg Air Force Base in California, the U.S.-European Sentinel-6 Michael Freilich ocean-monitoring satellite is being encapsulated in the SpaceX Falcon 9 payload fairing on 3 November 2020. (NASA)
The Sentinel-6 program includes two identical satellites, to be launched five years apart, Sentinel-6 Michael Freilich, which launched on 21 November 2020, and Sentinel-6B, which will launch in 2025. These satellites will measure sea level change from space, which have been measured without interruption since 1992.
Formerly called Sentinel-6A and Jason-CS A (Jason Continuity of Service-A), it was renamed in honor of the former director of NASA Earth Science Division, Michael Freilich, who was instrumental in advancing space-based ocean measurements. It follows the most recent U.S.-European sea level observation satellite, Jason-3, which launched in 2016, and is currently providing high-precision and timely observations of the topography of the global ocean.
Since the launch of TOPEX/Poseidon on 10 August 1992, high-precision satellite altimeters have been essential to monitor how the ocean stores and redistributes heat, water, and carbon in the climate system. The two satellites, Sentinel-6 Michael Freilich and Sentinel-6B, will extend this legacy through to at least 2030, which will provide a nearly forty-year record of sea level rise as well as changes in ocean currents.
The Sentinel-6 mission is part of the Copernicus programme initiative, the main objective of the Sentinel-6 mission is to measure sea surface topography with high accuracy and reliability to support ocean forecasting systems, environmental monitoring and climate monitoring.
The mission definition is driven by the need for continuity in provision of TOPEX/Poseidon mission and Jason satellite series (Jason-1, OSTM/Jason-2, and Jason-3) with improvements in instrument performance and coverage. ESA, NASA, and EUMETSAT will provide mission management and system engineering support. EUMETSAT and NASA will be responsible for long-term archives of altimetry data products. All partners will be involved with the selection of science investigators.
Responsibilities of partnersEdit
has responsibility for the development of the first satellite and the ground prototype processors, and for procurement of the second satellite on behalf of EUMETSAT and the European Commission
has responsibility for conducting the Launch and Early Operations Phase (LEOP) of both satellites
supports flight operations performed by EUMETSAT
has responsibility for ground segment development and coordination at system level, including for operations preparation
has responsibility for conducting operations of the two satellites after LEOP performed by ESA
has responsibility for conducting operations of the European part of the ground segment, including processing of altimeter data and delivery of product services to European users
has responsibility for the development and delivery of the U.S. payload instruments, the microwave radiometer and the GNSS radio occultation receiver
provides launch services for both satellites
provides ground segment development support and will contribute to operations and data processing on the U.S. side, including processing of GNSS radio occultation data
with NOAA, shares responsibility for the distribution of products to research and operational users in the U.S.
provides a U.S. ground station for tracking and command of the satellite and data downlinks
with NASA, shares responsibility for the distribution of products to research and operational users in the U.S.
has responsibility for processing higher-level products (L2P, L3)
has responsibility for providing precise orbit determination and support for Doris and altimeter operations 
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