CHIME (Copernicus Hyperspectral Imaging Mission for the Environment)

Quick facts

Overview

Summary

Mission Capabilities

Each CHIME satellite will carry a Hyperspectral Imager (HSI), a pushbroom-type grating imaging spectrometer designed for high signal-to-noise ratio and data uniformity. HSI will support the monitoring, implementation, and improvement of policies related to raw materials, food security, agriculture, and soil properties. Secondary applications include biodiversity and ecosystem sustainability, forestry management, environmental degradation monitoring, inland and coastal water quality, and snow and ice characterisation.

Performance Specifications

CHIME’s Hyperspectral Imager (HSI) acquires images across more than 200 spectral bands in the 400-2500 nm range, with an average spectral resolution of 10 nm and no spectral gaps. HSI will be able to measure at a ground resolution of 30 m and cover a swath width of around 130 km.

The two CHIME satellites will operate in sun-synchronous orbits at an altitude of 632 km with an orbital inclination of 97.9°, completing approximately 14.7 orbits per day. Together, they will achieve global coverage between latitudes of 84° North and 56° South, with a revisit time of 11 days at the equator when both platforms are operational (22 days with one satellite).

Space and Hardware Components

Thales Alenia Space France is the prime contractor for the CHIME space segment, with a consortium of 44 companies across 17 countries. HSI is developed by OHB (Germany), with Leonardo (Italy) supplying the focal plane assemblies and end-to-end calibration, and AMOS (Belgium) providing the spectrometers, gratings, and slits.

Each satellite has a launch mass of approximately 1640 kg, including 500 kg for the instrument, and is designed for a seven-year operational lifetime. The spacecraft operates in a gyroless nominal mode and includes autonomous, redundant onboard systems with GNSS, cloud detection, and AI-based data compression.

Overview

The Copernicus Hyperspectral Imaging Mission for the Environment (CHIME) is one of six new missions developed by the European Union (EU) and the European Space Agency (ESA) as part of the Copernicus Expansion missions. The mission includes two identical satellites, CHIME-A and CHIME-B. CHIME is designed to deliver systematic hyperspectral imaging in support of sustainable land management and environmental monitoring. 1) 2) 3)

Each satellite will carry a HyperSpectral Imager (HSI), a pushbroom-type grating imaging spectrometer optimised for signal-to-noise ratio and data consistency. CHIME will complement multispectral observations from multispectral optical imagers such as that carried by Sentinel-2.

CHIME’s space segment is led by Thales Alenia Space France as prime contractor, working with a consortium of 44 companies across 17 countries. The instrument is being developed by OHB (Germany), with contributions from Leonardo (Italy) for the focal plane assemblies and end-to-end calibration, and AMOS (Belgium) for the spectrometers, gratings, and slits.

Applications

CHIME’s hyperspectral observations will support a broad range of operational services and EU policy needs, primarily in sustainable agriculture, food security, and raw materials. Its data will also enable secondary applications in areas such as biodiversity, water quality, and ecosystem monitoring. 1) 2) 4) 5)

Spacecraft

Each CHIME satellite is designed for an operational lifetime of seven years, following a maximum of six months for launch and early orbit phase (LEOP) and in-orbit commissioning. Consumables are included to allow mission extension for up to twelve years. The satellites are compatible with both Vega-C and Ariane 6 launch vehicles. 1) 6)

 
At launch, each satellite will have a mass of approximately 1640 kg, of which around 500 kg is allocated to the HSI instrument. During imaging operations, CHIME consumes an average orbital power of about 1.0 kW, with the instrument accounting for roughly 300 W. 6) 7)

The platform of the CHIME satellites operates in a gyroless nominal mode, with a safe mode relying on a magnetometer, sun sensors, reaction wheels, and magnetic actuators. The onboard computer is fully autonomous and internally redundant, incorporating GNSS (Global Navigation Satellite System) receivers. CHIME has a data processing unit (DPU) capable of cloud detection and data compression, using artificial intelligence techniques. 3)

Orbit

The two CHIME satellites will operate in identical sun-synchronous orbits at an altitude of 632 km, with an inclination of 97.9° and an orbital period of approximately 97.5 minutes. They will be separated by 180°. Each satellite completes approximately 14.7 orbits per day, providing coverage of land surfaces between latitudes of 84° North and 56° South, including islands larger than 100 km2 and shallow coastal waters up to 50 m in depth. 1)

Observations are made when the solar zenith angle is below 84°, primarily during the descending part of the orbit, with a fixed local time of 10:45 AM at the descending node. CHIME achieves a revisit time of 22 days at the equator with one satellite, reduced to 11 days when both satellites are operational.

 
At the end of the satellite’s life, a controlled re-entry is planned. Additionally, each satellite includes passive interfaces to allow docking by an Active Debris Removal service, in the event of mission failure or disposal constraints.

Mission Status

• November 11, 2024: CHIME successfully completed testing on a model of the HSI instrument. The test was conducted at IABG’s facilities in Germany and verified the instrument’s readiness for launch and space operations. The model was placed in a vacuum chamber and subjected to extreme temperature variations to assess thermal performance. Structural integrity was confirmed through shaker testing, simulating the vibrations and acoustic loads of launch.  The results confirmed that the instrument meets all required tolerances, allowing the mission to proceed towards the next phase of development. Watch the test here. 8) 9)

• September 27, 2021: In preparation for CHIME’s operational phase, Hypersense, an international field campaign, was conducted by European and US scientists as part of a collaboration between ESA and NASA’s Jet Propulsion Laboratory (JPL). Initially delayed due to COVID-19, the campaign was led by the University of Zurich and involved flying JPL’s Next Generation Airborne Visible Infrared Imaging Spectrometer (AVIRIS) over more than 20 test sites.  AVIRIS was selected because it closely replicates the spectral capabilities CHIME will offer once in orbit. These sites represent various ecosystem types and were selected to validate and fine-tune CHIME’s expected performance. 10)

• November 13, 2020: ESA has signed contracts with Thales Alenia Space (France and Italy) and Airbus (Spain) for the development of three Copernicus Expansion missions: CHIME, CIMR, and LSTM. Thales Alenia Space France will lead the development of CHIME. The signing ceremony was attended by Bruno Le Maire, French Minister of the Economy and Finance. 11)
• July 3, 2020: Following the ESA Members’ financial commitments made at the Ministerial Level Space19+ Council, the Agency’s Industrial Policy Committee approved contracts worth €2.55 billion to advance the development of six new Copernicus missions, each comprising two satellites. The package is jointly funded by the EU and ESA Member States. Thales Alenia Space France was awarded the lead contract for CHIME, valued at €455 million. 12)

Sensor Complement

HyperSpectral Imager (HSI)

Each CHIME satellite carries a Hyperspectral Imager (HSI), a pushbroom-type imaging spectrometer designed to acquire high-resolution, radiometrically accurate data across the visible to short-wave infrared range (400-2500 nm). The instrument captures images in more than 200 spectral bands with an average spectral resolution of 10 nm and no gaps between bands. HSI has a ground resolution of 30 m, with a swath width of approximately 130 km. 1) 2)

The system uses a Three Mirror Anastigmat telescope (TMA) with mirrors to direct incoming light to three identical spectrometers. Each spectrometer processes one-third of the swath while covering the full spectral range. A neutral fold mirror distributes the light to each spectrometer, as seen in Figure 9, where spectral dispersion is achieved through dual-blazed gratings. The dispersed images are detected by Mercury Cadmium Telluride (MCT) detectors, each with 3000 x 512 pixels. These detectors require cooling to around -100℃. This is achieved using a thermal control system that includes a baffled cryogenic radiator, graphite thermal straps, and ethane heat pipes. All optical elements are mounted on a carbon fibre reinforced polymer (CFRP) bench structure, designed to maintain thermal and mechanical stability. The temperature of the optical components is stabilised at around 20℃. 7) 13)

Ground Segment

CHIME will be integrated into the existing Copernicus Ground Segment, which supports all Copernicus missions operated by ESA. This system enables data acquisition, processing, and archiving through a cloud-based, service-oriented architecture. CHIME’s payload data will be downlinked via Ka-Band. The ground segment handles all core functions, including mission planning, instrument monitoring, calibration, and public data access via the Copernicus Data Space Ecosystem. 14)

References  

1) SentiWiki, “CHIME,” URL: https://sentiwiki.copernicus.eu/web/chime

2) Future Earth, “PLANS FOR A NEW WAVE OF EUROPEAN SENTINEL SATELLITES,” URL: https://futureearth.org/wp-content/uploads/2020/01/issuebrief_04_03.pdf

3) ESA, “CHIME Copernicus Hyperspectral Imaging Mission for the Environment Brochure,” URL: https://indd.adobe.com/view/b452927f-984e-4616-80b6-b69bc8422ed3

4) ESA, “Copernicus Sentinel Expansion missions,” URL: https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Copernicus_Sentinel_Expansion_missions

5) Celesti et al., “The Copernicus Hyperspectral Imaging Mission For The Environment (CHIME): Current Status,” URL: https://www.enmap.org/data/1st_WS_Online/Session_III/2023_EnMAP_User_Workshop_M.Celesti.pdf 

6) Thales Alenia Space, “Thales Alenia Space to build Copernicus CHIME satellites,” 13 November 2020, URL: https://www.thalesgroup.com/en/worldwide/space/press-release/thales-alenia-space-build-copernicus-chime-satellites 

7) Cleren and Schibilla, “Thermal Design of the Hyperspectral Instrument of the CHIME Mission,” 52nd International Conference on Environmental Systems, 16-20 July 2023, URL: https://ttu-ir.tdl.org/server/api/core/bitstreams/17bccd7e-180e-4133-a1a4-1eb0b2c0e19b/content

8) ESA, “CHIME given the shakes,” 12 November 2024, URL: https://www.esa.int/Applications/Observing_the_Earth/Copernicus/CHIME_given_the_shakes 

9) ESA, “CHIME team at IABG,” 12 November 2024, URL: https://www.esa.int/ESA_Multimedia/Images/2024/11/CHIME_team_at_IABG 

10) ESA, “Going hyperspectral for CHIME,” 27 September 2021, URL: https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Going_hyperspectral_for_CHIME 

11) ESA, “Contracts signed for three high-priority environmental missions,” 13 November 2020, URL: https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Contracts_signed_for_three_high-priority_environmental_missions 

12) ESA, “Contracts awarded for development of six new Copernicus missions,” 3 July 2020, URL: https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Contracts_awarded_for_development_of_six_new_Copernicus_missions 

13) Spacenews, “Teledyne e2v confirms VNIR-SWIR detector supply contract for CHIME Copernicus mission,” 6 April 2021, URL: https://spacenews.com/teledyne-e2v-confirms-vnir-swir-detector-supply-contract-for-chime-copernicus-mission/

14) SentiWiki, “Copernicus Operations,” URL: https://sentiwiki.copernicus.eu/web/copernicus-operations