India-France TRISHNA satelliteISRO (Indian Space Research Organisation) and the CNES (Centre National d'Etudes Spatiales) have collaborated to develop the TRISHNA (Thermal InfraRed Imaging Satellite for High-resolution Natural Resource Assessment) satellite which is targeted for launch in 2025. Equipped with three instruments, the TRISHNA satellite will have a lifespan of five years and will be installed in a sun-synchronous orbit at an altitude of 666 km. The satellite will be launched using ISRO's Polar Satellite Launch Vehicle (PSLV) and will be controlled by the U R Rao Satellite Centre in Bengaluru.
The CNES says that TRISHNA will enhance our understanding of the water cycle and improve the management of water resources to better define the impacts of climate change, especially at the local level. It will observe the surface temperature of oceans and the data will be applied particularly in agriculture and hydrology. Its applications will also extend to surveillance of continental and coastal waters, follow-up of urban heat traps, monitoring fire and volcanic activity, and studying glaciers and frozen lakes.
Horizon 2047: 25th Anniversary of the India-France Strategic Partnership, Towards A Century of India-France Relations· 3) Putting space at the heart of our strategic relationship· 3.1 Access to space, space technologies and the development of services and applications using space data and capabilities are at the heart of our societies' innovation, scientific development and economic growth. India and France have decided to deepen their cooperation in all areas of the space sector by strengthening their programmes of common interests including:· 3.2.1 Scientific and commercial partnership: CNES and ISRO will strengthen their partnership mainly around two structuring axes: climate and environment, with the development of the TRISHNA mission and activities within the Space Climate Observatory (SCO) on topics such as water resource management, marine resources and air quality monitoring; space exploration (Mars, Venus), maritime monitoring, launchers and manned flights in connection with India’s Gaganyaan programme. NSIL and Arianespace also plan to collaborate in commercial launch services.· 3.2.2 Resilience of access to space: India and France will work to strengthen their synergies in terms of sovereign access to space and the development of forward-looking technologies to boost the resilience of access to space with involvement of their space industries.· 3.2.3 India and France will also continue to engage through the recently institutionalised bilateral strategic space dialogue.
Trishna is a French-Indian mission to acquire imagery of Earth’s surface in the thermal infrared with a resolution and revisit frequency never seen before. The satellite is scheduled to launch in late 2024.Developed by CNES and its Indian counterpart ISRO, the Trishna mission is designed to observe Earth’s surface in the thermal infrared domain. Temperature is an indicator of the energy budget of all kinds of land surfaces, for example croplands, pastures and forests, urban areas or snow and ice. This budget yields a wealth of information such as plant water stress and evapotranspiration. For water surfaces, time-series of satellite temperature images are dynamic indicators of the structures involved in mixing the waters of lakes, rivers, their estuaries and the oceans.Today, temperature measurements from space can only be obtained monthly at a resolution of about 100 metres, and daily global measurements are only available at a resolution of one kilometre.The goal of Trishna—for Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment—is to reach a resolution of 57 metres with a revisit interval of three days. That kind of detailed spatial and temporal resolution will enable scientists to understand the local evolution of biological (water stress, transpiration), physical (evaporation, sublimation, plumes) and climatic (global observation over time) phenomena in relation to the water cycle. Ultimately, Trishna will be a precious aid to inform policy decisions for farming, water resource management and land planning.Trishna’s thermal infrared instrument, developed by CNES, will be supplemented by an optical sensor supplied by ISRO. Observing simultaneously in the visible and thermal portions of the spectrum will make it easier to juxtapose data for analysis in several fields of investigation:- ecosystem water stress and water resource management- hydrology of coastal strips and land surfaces- urban heat islands- cryosphere- atmosphere
TRISHNA: a Franco-Indian Mission to Monitor the Water Status of Continental EcosystemsA mission with a high temporal resolutionTRISHNA (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment) is a future high-resolution space-time mission in the thermal infrared (TIR) led jointly by the French (CNES) and the Indian (ISRO) space agencies for a launch planned in 2025. The scientific objectives guiding the definition of the mission are, in order of priority, the monitoring of the water status and of the stress of continental ecosystems, the monitoring of coastal and inland waters, the urban environment, and applications to the solid Earth, the cryosphere and the atmosphere.TRISHNA will be positioned on a polar orbit at an altitude of 761 km, providing a revisit of 3 passages over 8 days with global coverage. The time of passage around 13:00 LST allows thermal data to be acquired in the middle of the day, but also in the middle of the night. The instrument will offer 4 thermal channels (8.6 µm, 9.1 µm, 10.4 µm, 11.6 µm) and 6 optical channels (485 nm, 555 nm, 650 nm, 860 nm, 1 380 nm, 1 650 nm) with a spatial resolution between 50 m and 60 m for all channels. The required accuracy is 1k with a NeDT of 0.2K.TRISHNA will have a large field of view of 35° to ensure global coverage, generating directional effects whose magnitude has been measured in situ up to 5°C (forests) and 10°C (vineyards, urban). In the intertropical zone and from March to October, one of the three successive observations will be contaminated by the hot spot phenomenon which consists in observing the target in the direction of illumination. Parametric models (Roujean-Lagouarde, RL), 1D (SCOPE) and 3D (DART) are being studied to best overcome angular stress based on better control of directional anisotropy in the IRT. The GWS (Global Split Window) and TES (Temperature Emissivity Separation) methods will be used to estimate the surface temperature corrected for atmospheric and emissivity effects.A structured research systemA scientific mission group was structured into eight Franco-Indian thematic subgroups (Ecosystem stress, Coastal and Continental Waters, Urban, Cryosphere, Atmosphere, Solid Earth, Cal/Val, Product Development). The subgroups’ activities are multiple and range from the consolidation of mission specifications (directional variability, characterization of the impact of atmospheric turbulence, emissivity estimation, position and width of thermal spectra) to the definition of products and their validation on in situ networks. Finally, the subgroups ensure the link with Indian partners on each of the themes, in particular through scientific exchanges and the setting up of collaborative projects.The ultimate objective is to co-construct future processing chains, to size and validate error items, and to promote the use and dissemination of data in the community. For example, an end-to-end simulator is being developed for vegetation in CNES for this purpose with the help of the “ecosystem braid” group.
List of Indian Earth observing satellites with scheduled launch time period; the list appears to have been updated in October 2022:http://database.eohandbook.com/database/agencysummary.aspx?agencyID=11Approved MissionsOCEANSAT-3 Nov 2022 (launched Nov 26)NISAR Sep 2023 (other sources say 2024)TRISHNA Dec 2024OCEANSAT-3A Nov 2025RESOURCESAT-3 Nov 2025RESOURCESAT-3S Jun 2026Planned MissionsINSAT-3DS 2023RISAT-1B 2023RESOURCESAT-3A 2026RESOURCESAT-3SA 2027Considered MissionsnoneHRSAT (was Aug 2023 launch) and ATMSAT-1 (was 2025 launch) are gone from the list.
List of Indian Earth observing satellites with scheduled launch time period; the list appears to have been updated in H1 2024, maybe June:http://database.eohandbook.com/database/agencysummary.aspx?agencyID=11Approved MissionsNISAR Oct 2024 (now Jan 2025)RISAT-1B Dec 2024OCEANSAT-3A Nov 2025TRISHNA Dec 2026Planned MissionsRESOURCESAT-3S 2025RESOURCESAT-3 2025RESOURCESAT-3SA 2026RESOURCESAT-3A 2026Considered Missionsnone
