Sentinel 6 Michael Freilich

Dr. Michael Freilich, the previous head of NASA’s Earth Science Division and a relentless supporter of improving ocean satellite observations, is honoured with the name of the spacecraft. Sentinel-6 Michael Freilich builds on the legacy of the Copernicus Sentinel-3 mission of the European Space Agency, as well as the TOPEX/Poseidon and Jason-1, 2, and 3 series of sea-level observation satellites from the United States and Europe. Jason-3 was launched in 2016 and is presently supplying data that began with TOPEX/Poseidon observations in 1992.

Over the last 30 years, data from these satellites has become the gold standard for sea-level studies from space. Sentinel-6 Michael Freilich’s twin, Sentinel-6B, is set to launch in 2025, allowing these measurements to be advanced for at least another half-decade.

Jason-CS Mission: 

The Jason Continuity of Service (Jason-CS) program is a multinational collaboration between the United States and Europe to monitor oceans using the Sentinel-6 satellite. The Jason-CS project will launch two identical spacecraft (Satellite A and Satellite B) in 2020 and 2025. Sentinel-6 Michael Freilich was renamed in February 2020 in honour of Dr. Michael Freilich, director of NASA’s Earth Science Division (2006-2019), who died in August 2020.

The satellite was developed jointly by the European Space Agency (ESA), NASA, the European Organisation for the Exploitation of Meteorological Satellites (Eumetsat), and the National Oceanic and Atmospheric Administration (NOAA) of the United States, and the European Union.

Sentinel-6 Michael Freilich: 

Copernicus Sentinel-6 will be launched as the global mean sea level rises as a result of climate change. The next radar altimetry reference mission, Michael Freilich, will extend the legacy of sea-surface height data until at least 2030. Sentinel-6 is a Copernicus mission that is implemented and co-funded by the European Commission, ESA, EUMETSAT, NASA and the National Oceanic and Atmospheric Administration in the United States (NOAA).

The LEOP (Launch and Early Orbit Phase) was completed on November 24, 2020, when ESA’s mission control team handed over command and control of the satellite to EUMETSAT, Europe’s weather and climate satellite organization, which completed the final ‘orbit acquisition’ and assumed responsibility for commissioning, routine operations, and distribution of the mission’s critical data.

Purpose of Sentinel-6 Michael Freilich: 

According to NASA, the satellite will ensure that sea-level observations continue into the fourth decade and will give global sea-level rise readings.

• Scientists have used high-precision satellite altimeters to better understand how the ocean stores and distributes heat, water, and carbon in the climate system since 1992
• Essentially, the satellite will transmit pulses to the Earth’s surface and monitor how long it takes for them to return, allowing scientists to determine the height of the sea surface. It will also use GPS and ground-based lasers to monitor water vapour along this journey and determine its location
• Additionally, the information gathered will aid operational oceanography by improving forecasts of ocean currents, wind, and wave conditions. Short-term forecasting for weather predictions in the two-to-four-week range (hurricane strength predictions) and long-term forecasting, for example for seasonal conditions like El Nio and La Nina, will benefit from this data

Characteristics: 

The Sentinel-6 Space Segment is made up of two Jason-CS satellites (A and B), both based on the CryoSat-2 legacy platform and customized to the Sentinel-6 mission’s demands. The following main payload will be carried by the satellites:

• A radar altimeter (Poseidon-4) that uses two different frequencies to estimate the distance between the satellite and the mean ocean surface, assess significant wave height and wind speed and account for altimeter range path delay in the ionosphere (Ku-band and C-band)
• JPL’s AMR-C (Advanced Microwave Radiometer-C) microwave radiometer, which corrects the altimeter range measurement for the wet tropospheric route delay
• Precise Orbit Determination instruments such as a GNSS (Global Navigation Satellite System) and precise orbit determination receiver (GNSS-POD), a DORIS instrument, and an LRA (Laser Retroreflector Array) to provide a measurement of the orbital position with high accuracy and precision, as required for the conversion of altimeter range into a sea
• The GNSS-RO (GNSS-Radio Occultation) instrument tracks GNSS satellites to produce all-weather atmospheric and ionospheric soundings (with high vertical resolution)

Importance of measuring the height of the ocean: 

Only from space, it is possible to monitor key changes in ocean currents and heat storage, as well as examine the height of the sea on a worldwide scale. It aids scientists in predicting the consequences of shifting oceans on climate change. Scientists need to know the ocean currents and heat storage of the seas, which may be determined from the height of the sea surface, in order to quantify and track changes in the marine heat budget.

Conclusion: 

Sentinel-6 Michael Freilich will now take up this mission from the Jason-3 satellite, which was launched in January 2016 and will collect environmental data for at least five years. The Copernicus Sentinel-6B satellite, which will continue the measurement series into the next decade, is set to launch in 2025. 

The first Sentinel-6 satellite is called ‘Michael Freilich’ in honor of the former Director of Earth Sciences at NASA, who died, for his contributions to Earth observation and maritime satellite observations.