The Copernicus Hyperspectral Imaging Mission (CHIME) is a part of the six new missions aimed at broadening the current range of Sentinel missions. CHIME comprises of two satellites, namely CHIME-A and CHIME-B. These satellites are designed to provide systematic hyperspectral images that can be used to map changes in land cover and support sustainable agricultural practices.
CHIME is designed for 7 years of operational lifetime, following 6 months (max) of LEOP and in-orbit commissioning. The satellite embarks consumables sufficient to extend its lifetime up to 12 years. A controlled re-entry is envisaged at end of life (EOL). In addition to this EOL re-entry capability the CHIME spacecraft provides passive interfaces for the docking of an Active Debris Removal service to remove the spacecraft from the LEO protected region, in case of loss of mission or inability to perform a safe disposal.
The two identical satellites flying will be separated by 180 degrees, in a sun-synchronous orbit at an average altitude of 632 km. Each satellite will complete 14+17/22 orbits per day, making observations of all land areas between the latitudes 84 degrees North and 56 degrees South, including islands greater than 100 km2 and open water wherever the depth does not exceed 50 meters. In addition, thanks to the ample on-board storage and downlink on-board resources, the coastal areas coverage is guaranteed up to 370 km from land, well beyond the 50 km specified in the mission requirements.
CHIME satellites will be in a sun-synchronous orbit at an altitude of 632 km with an orbital inclination of 97.9°. The orbital period of these satellites will be 97.5 minutes with a 25-day repeat cycle.
The HyperSpectral Imager (HSI) will be carried on board each CHIME satellite. This will be a pushbroom-type grating Imaging Spectrometer with high Signal-to-noise ratio and data uniformity. The purpose of HSI is to support monitoring, implementation, and improvement of various policies related to raw material, food security, agriculture, and soil properties. Apart from this, HSI will also have secondary applications in areas such as biodiversity and ecosystem sustainability, forestry management, environmental degradation, lake/coastal ecosystems, water quality, and snow characteristic
The HSI has the ability to measure at a ground resolution of 30 m for a swath width of 130 km with high radiometric accuracy for Level-1B data. It is an advanced hyperspectral imager that can capture images in over 200 bands over a wavelength range of 400 nm - 2500 nm in the Visible (VIS), Near Infrared (NIR), and Short-Wave Infrared (SWIR) spectrum at a spectral bandwidth less than 10 nm.
CHIME observations will take place whenever the sun zenith angle is lower than 84 degrees, meaning that, with the local time at the descending node being fixed at 10:45 AM, the vast majority of observations will take place during the descending part of the orbit.
The combination of the above characteristics with the wide swath width of 130 km provided by the HSI payload will allow CHIME to provide global hyperspectral coverage of land surfaces, inland and coastal waters with a high revisit time, under cloud-free conditions, of 22 days at the equator with one satellite, and 11 days with two satellites.
Figure 2: CHIME observation map
Table 1: CHIME key mission requirements.
All land and inland water bodies between 56° S and 84° N
Islands greater than 100 km2
Coastal zones within 50 km from land
Open water with the depth < 50 m
400 – 2500 nm
< 0.1 SSD
< 0.1 SSI
Figure 3: CHIME spacecraft in nominal flight configuration.
The CHIME mission will respond to the user need for applications related to sustainable agriculture and food security, as well as raw materials exploration and management, as primary drivers. Additionally, CHIME products have been acknowledged for their relevance in other areas such as biodiversity, forestry, coastal/inland waters, and cryosphere monitoring by the respective user communities.
The CHIME mission's primary objective is to support the development of new and improved operational applications and services that are related to food security, sustainable agriculture, and raw materials.
As a secondary objective, CHIME will support operational applications and services related to inland and coastal waters quality, biodiversity, snow and ice properties, environmental degradation, and hazards.
In addition to serving operational users such as the Copernicus Services, CHIME data will also significantly contribute to a wide range of scientific research activities that support the development and quality of downstream applications. A recent analysis has highlighted that this is already the case for existing Sentinels.
Sustainable agricultural and biodiversity management
Soil property characterisation
CHIME-A working launch date is in 2028 while CHIME-B is planned to be launched in 2030 with both satellites having a design life of eight years.
 The Copernicus Hyperspectral Imaging Mission for the Environment (CHIME) – An overview of its mission, system and planning status