Sentinel-2 Explained

Sentinel-2
Manufacturer:
Operator:European Space Agency
Applications:Land and sea monitoring, natural disasters mapping, sea ice observations, ships detection
Spacecraft Type:Satellite
Spacecraft Bus:AstroBus-L
Constellation:2
Design Life:7 years
Launch Mass:2513lb
Dry Mass:2240lb
Dimensions:3.4xx
Power:1,700 W[2]
Status:Active
Built:3
Launched:2
Operational:2
First:Sentinel-2A
Last:Sentinel-2B
Previous:Sentinel-1
Next:Sentinel-3

Sentinel-2 is an Earth observation mission from the Copernicus Programme that acquires optical imagery at high spatial resolution (10 m to 60 m) over land and coastal waters. The mission's Sentinel-2A and Sentinel-2B satellites are to be joined in orbit in 2024 by a third, Sentinel-2C, and in the future by Sentinel-2D, eventually replacing the A and B satellites, respectively.[3]

The mission supports services and applications such as agricultural monitoring, emergencies management, land cover classification, and water quality.

Sentinel-2 has been developed and is being operated by the European Space Agency. The satellites were manufactured by a consortium led by Airbus Defence and Space in Friedrichshafen, Germany.

Overview

The Sentinel-2 mission includes:

To achieve frequent revisits and high mission availability, two identical Sentinel-2 satellites (Sentinel-2A and Sentinel-2B) operate together. The satellites are phased 180 degrees from each other on the same orbit. This allows for what would be a 10-day revisit cycle to be completed in 5 days.[4] The 290 km swath is created by the VNIR and SWIR, which are each made of 12 detectors that are lined in two offset rows.[5]

The orbits are Sun-synchronous at 786km (488miles) altitude, 14.3 revolutions per day, with a 10:30 a.m. descending node. This local time was selected as a compromise between minimizing cloud cover and ensuring suitable Sun illumination. It is close to the Landsat local time and matches SPOT, allowing the combination of Sentinel-2 data with historical images to build long-term time series.

Launches

The launch of the first satellite, Sentinel-2A, occurred 23 June 2015 at 01:52 UTC on a Vega launch vehicle.[6]

Sentinel-2B was launched on 7 March 2017 at 01:49 UTC,[7] also aboard a Vega rocket.[8]

Sentinel-2C is scheduled to launch in 2024 on a Vega launch vehicle.[9]

Instrument

The Sentinel-2 satellites each carry a single instrument, the Multi-Spectral Instrument (MSI), which has 13 spectral channels in the visible/near infrared (VNIR) and short wave infrared spectral range (SWIR). Within the 13 bands, the 10m (30feet) spatial resolution allows for continued collaboration with the SPOT-5 and Landsat-8 missions, with the core focus being land classification.[10]

Designed and built by Airbus Defense and Space in France, the MSI uses a push-broom concept and its design was driven by the large 290km (180miles) swath requirements together with the high geometrical and spectral performance required of the measurements.[11] It has a 1500NaN0 aperture and a three-mirror anastigmat design with a focal length of about 600mm; the instantaneous field of view is about 21° by 3.5°.[12] The mirrors are rectangular and made of silicon carbide, a similar technology to those on the Gaia astrometry mission. The MSI system also employs a shutter mechanism preventing direct illumination of the instrument by the sun. This mechanism is also used in the calibration of the instrument.[13] Out of the existing civic optical earth observation missions, Sentinel-2 is the first acquiring three bands in the red edge.[10] MSI has 12-bit radiometric resolution (bit depth) with brightness intensity ranging from 0–4095.[14]

Spectral bands

Sentinel-2 bands! colspan="2"
Sentinel-2ASentinel-2B
Central wavelength (nm)Bandwidth (nm)Central wavelength (nm)Bandwidth (nm)Spatial resolution (m)
Band 1 – Coastal aerosol442.721442.22160
Band 2 – Blue492.466492.16610
Band 3 – Green559.836559.03610
Band 4 – Red664.631664.93110
Band 5 – Vegetation red edge704.115703.81620
Band 6 – Vegetation red edge740.515739.11520
Band 7 – Vegetation red edge782.820779.72020
Band 8 – NIR832.8106832.910610
Band 8A – Narrow NIR864.721864.02220
Band 9 – Water vapour945.120943.22160
Band 10 – SWIR – Cirrus1373.5311376.93060
Band 11 – SWIR1613.7911610.49420
Band 12 – SWIR2202.41752185.718520

Temporal offsets

Due to the layout of the focal plane, spectral bands within the MSI observe the surface at different times and vary between band pairs.[13] These temporal offsets can be used to gain additional information, for example to track propagating natural and human-made features such as clouds, airplanes or ocean waves[15] [16]

Applications

Sentinel-2 serves a wide range of applications related to Earth's land and coastal water.

The mission provides information for agricultural and forestry practices and for helping manage food security. Satellite images will be used to determine various plant indices such as leaf area chlorophyll and water content indexes. This is particularly important for effective yield prediction and applications related to Earth's vegetation.

As well as monitoring plant growth, Sentinel-2 is used to map changes in land cover and to monitor the world's forests. It also provides information on pollution in lakes and coastal waters. Images of floods, volcanic eruptions [17] and landslides contribute to disaster mapping and help humanitarian relief efforts.

Examples of applications include:

The Sentinel Monitoring web application offers an easy way to observe and analyse land changes based on archived Sentinel-2 data.[22]

Products

The following two main products are generated by the mission:[23]

Additionally, the following product for expert users is also available:

External links

Notes and References

  1. Web site: Sentinel 2 . Earth Online . European Space Agency . 17 August 2014.
  2. Web site: Sentinel-2 Data Sheet . . August 2013.
  3. Web site: Gearing up for third Sentinel-2 satellite . . 9 August 2021 . 9 August 2021.
  4. Web site: Orbit - Sentinel 2 - Mission - Sentinel Online. sentinel.esa.int. 2020-03-05.
  5. Web site: Sentinel-2 - Missions - Instrument Payload - Sentinel Handbook. sentinel.esa.int. 2020-03-05.
  6. News: Arianespace successfully launches Europe's Sentinel-2A Earth observation satellite . Spaceflight Insider . Tomasz . Nowakowski . 23 June 2015 . 17 August 2016 . 10 January 2021 . https://web.archive.org/web/20210110022631/https://www.spaceflightinsider.com/missions/earth-science/arianespace-successfully-launches-europes-sentinel-2a-earth-observation-satellite/ . dead .
  7. News: Sentinel-2B rides Vega to join Copernicus fleet . . Chris . Bergin . 6 March 2017 . 9 March 2017.
  8. News: ESA's Sentinel 2B spacecraft steps into the spotlight . Spaceflight Insider . Jacques . van Oene . 17 November 2016 . 17 November 2016 . 12 December 2016 . https://web.archive.org/web/20161212103937/http://www.spaceflightinsider.com/organizations/esa/esas-sentinel-2b-spacecraft-steps-spotlight/ . dead .
  9. Web site: Parsonson . Andrew . The Case of the Missing Vega AVUM Propellant Tanks . European Spaceflight . 4 December 2023 . 5 December 2023.
  10. Web site: Copernicus: Sentinel-2 - Satellite Missions - eoPortal Directory. directory.eoportal.org. 2020-03-05.
  11. Web site: Sentinel-2 MSI: Overview . European Space Agency. 17 June 2015.
  12. GMES Sentinel-2 MSI Telescope Alignment. International Conference on Space Optics. 9–12 October 2012. Ajaccio, France.. Vincent. Chorvalli. 9 October 2012. 23 February 2017. 31 October 2020. https://web.archive.org/web/20201031173632/https://esaconferencebureau.com/custom/icso/2012/presentations/034_Chorvalli.pdf. dead.
  13. Web site: MSI Instrument – Sentinel-2 MSI Technical Guide – Sentinel Online. earth.esa.int. 2019-02-07. 17 October 2020. https://web.archive.org/web/20201017053209/https://earth.esa.int/web/sentinel/technical-guides/sentinel-2-msi/msi-instrument. dead.
  14. Web site: Radiometric - Resolutions - Sentinel-2 MSI - User Guides - Sentinel Online. sentinel.esa.int. 2020-03-05.
  15. Kudryavtsev. Vladimir. Yurovskaya. Maria. Chapron. Bertrand. Collard. Fabrice. Donlon. Craig. January 2017. Sun glitter imagery of ocean surface waves. Part 1: Directional spectrum retrieval and validation. Journal of Geophysical Research. 122. 16. 1918. 10.1002/2016JC012425. 2017JGRC..122.1369K. free.
  16. Maisongrande. Philippe. Almar. Rafael. Bergsma. Erwin W. J.. January 2019. Radon-Augmented Sentinel-2 Satellite Imagery to Derive Wave-Patterns and Regional Bathymetry. Remote Sensing. 11. 16. 1918. 10.3390/rs11161918. 2019RemS...11.1918B. free.
  17. Mapping Recent Lava Flows at Mount Etna Using Multispectral Sentinel-2 Images and Machine Learning Techniques . Remote Sensing . 2019 . 16 . 11 . 1916 . 10.3390/rs11161916 . 2019RemS...11.1916C . free . Corradino . Claudia . Ganci . Gaetana . Cappello . Annalisa . Bilotta . Giuseppe . Hérault . Alexis . Del Negro . Ciro .
  18. Brandolini F, Domingo-Ribas G, Zerboni A et al. A Google Earth Engine-enabled Python approach for the identification of anthropogenic palaeo-landscape features [version 2; peer review: 2 approved, 1 approved with reservations]. Open Research Europe 2021, 1:22 (https://doi.org/10.12688/openreseurope.13135.2)
  19. ((Orengo, H. A.)), ((Petrie, C. A.)) . Remote Sensing . Large-scale, multi-temporal remote sensing of palaeo-river networks: A case study from Northwest India and its implications for the Indus civilisation . 9 . 7 . 735 (1–20) . 16 July 2017 . 2072-4292 . 10.3390/rs9070735. free . 2017RemS....9..735O . 2072/332335 . free .
  20. ((Buławka, N.)), ((Orengo, H. A.)) . Remote Sensing . Application of multi-temporal and multisource satellite imagery in the study of irrigated landscapes in arid climates . 16 . 11 . 1997 . 2024 . 10.3390/rs16111997. free .
  21. Corradino. Claudia. Bilotta. Giuseppe. Cappello. Annalisa. Fortuna. Luigi. Del Negro. Ciro. 2021. Combining Radar and Optical Satellite Imagery with Machine Learning to Map Lava Flows at Mount Etna and Fogo Island. Energies. en. 14. 1. 197. 10.3390/en14010197. free.
  22. Web site: Sentinel Monitoring . Sentinel Hub/Sinergise . 26 August 2016.
  23. Web site: Sentinel-2 MSI: Product Types . European Space Agency . 17 June 2015.