Sentinel-4

The Senitinel-4 is an instrument aboard the MTG-S satellites. Its main function is air quality monitoring as part of the Sentinel satellites series under the Copernicus program 

Mission Objective

Sentinel-4’s main objective is to observe the daily cycle of tropospheric composition by monitoring key air quality aerosols and trace gases above Europe and North Africa as part of the Copernicus Atmosphere Monitoring Service.

Mission Significance

The mission’s data will contribute to many aspects related to air quality, including supporting the needed European policies, enhancing weather forecasting, improving public health management, and advancing climate research needs.

Source: ESA

Engineering Challenges

The Sentinel-4 mission must deliver continuous, high-resolution atmospheric monitoring from geostationary orbit, requiring uninterrupted instrument stability, consistent calibration, and precise scanning over Europe every hour. The UVN spectrometer and IRS must withstand harsh GEO radiation, maintain thermal equilibrium, and operate reliably for more than a decade. These constraints demand advanced optical materials, long-term calibration stability, and exceptional protection against stray light and contamination.

Mission Components 

The instrument of Sentinel-4 will be hosted on an MTG-S satellite. The MTG is the Meteosat Third Generation space system of satellites. It is the third model of meteorological satellites that is developed by TAS. Those satellites represent the next generation in numerical weather prediction and forecasting. Its remarkable profiling technology and high resolution will allow reliable weather forecasting in both the short and long term. The MTG space system consists of two satellite families – MTG-I (imager) and MTG-S (sounder).

The Sentinel-4 mission will be included in two MTG-S satellites planned to be launched separately – MTG-S1 in 2024 and MTG-S2 in 2034. Both will include the same payload of instruments:

• The Sentinel-4 instrument – S4 UVN Multispectral Spectrometer: a hyperspectral spectrometer that uses spectral bands within the solar reflectance spectrum – the UV, visible, and NIR spectral bands. The time of full circle around Earth is 1 hour and its spatial sampling dimensions is 4 km²
• Infra-Red Sounder (IRS): a Fourier transform spectrometer. Its main goal is to detect the structure of atmospheric gases and data transferring to the ground, enabling more accurate and reliable weather forecasting.

Source: ESA

Acktar’s Solution

The Sentinel-4 mission must deliver continuous, high-resolution atmospheric monitoring from geostationary orbit, requiring uninterrupted instrument stability, consistent calibration, and precise scanning over Europe every hour. In addition to withstanding severe radiation conditions, thermal equilibrium maintenance, and long-term operation. These constraints demand advanced optical materials, long-term calibration stability, and exceptional protection against stray light and contamination.

Impact

This mission will play an essential role in enhancing air quality monitoring and climate studies in general. Its capabilities mark a pivotal step forward in atmospheric monitoring, supporting vital scientific discoveries and governmental decision-making for years.

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