TRISHNA Mission: ISRO-CNES Thermal Infrared Satellite for Water & Agriculture | UPSC

Why in News

The TRISHNA mission — a joint Earth observation satellite between ISRO (Indian Space Research Organisation) and CNES (Centre National d'Études Spatiales, France) — is in its advanced development phase, with the Thermal InfraRed (TIR) instrument delivered by CNES to ISRO in 2026 for integration with the satellite bus. The mission is scheduled for launch aboard a PSLV from Satish Dhawan Space Centre, Sriharikota, with the current planned launch window in October 2027. TRISHNA is the third major Indo-French space collaboration, following Megha-Tropiques (2011) and SARAL-AltiKa (2013), and was formally approved at bilateral talks in March 2024.

Background: Indo-French Space Partnership

India and France have maintained one of the most substantive bilateral space partnerships in the world. The Indo-French Joint Commission on Space Cooperation operates under the overall Strategic Partnership Agreement between the two countries. Key joint missions:

Mission	Launch	Purpose
Megha-Tropiques	2011	Tropical atmospheric water cycle monitoring
SARAL-AltiKa	2013	Ocean surface altimetry and significant wave height
TRISHNA	2027 (planned)	Thermal infrared surface monitoring

The cooperation is institutionally anchored in the India-France Joint Statement (July 2023) during PM Modi's state visit to France, and the formal approval for TRISHNA was granted on March 19, 2024 by the respective space agencies.

Mission Overview

Full Form

Thermal infRared Imaging Satellite for High-resolution Natural resource Assessment

Orbit and Parameters

Orbit type: Polar Sun-Synchronous Orbit (SSO)
Altitude: ~761 km
Local solar time (descending node): 12:30–13:30 (afternoon overpass — captures peak surface temperatures)
Revisit interval: ~3 days
Repeat cycle: 8 days
Mission life: 5 years (extendable by 2 years)

Instruments

Instrument	Full Name	Built by	Spatial Resolution	Spectral Coverage
TIR	Thermal InfraRed	CNES (France)	57 m	8–12 μm (4 long-wave IR channels); 1,026 km swath; noise <0.3 K
VNIR-SWIR	Visible Near-InfraRed / Short-Wave InfraRed	ISRO (India)	20 m	7 channels — visible through shortwave infrared

Division of Responsibility

ISRO: Satellite bus design and fabrication, VNIR-SWIR instrument, PSLV launch, satellite operations
CNES: TIR instrument development, TIR electronics, data processing infrastructure and algorithms
Data sharing: Both agencies receive full access to mission data; data will be available to the global scientific community through a defined open-data policy

Key Facts

Mission type: Earth Observation (thermal infrared focus)
Joint mission partners: ISRO (India) + CNES (France)
Formally approved: March 19, 2024
Planned launch: October 2027 (PSLV, SDSC-SHAR, Sriharikota)
TIR instrument delivered to ISRO: 2026
Swath width (TIR): 1,026 km — enables global coverage in ~3 days
Noise Equivalent Temperature Difference (NETD): <0.3 K — high thermal sensitivity

Mission Objectives and Applications

1. Water Resource Management

TRISHNA's primary application is mapping evapotranspiration (ET) — the combined loss of water through evaporation from soil and transpiration from plants. Accurate ET mapping at 57 m resolution will help India's irrigation planning authorities, watershed managers, and river basin authorities optimise water use across 140 million hectares of agricultural land. It directly supports India's National Water Mission under the National Action Plan on Climate Change (NAPCC).

2. Agricultural Drought and Crop Water Stress

By detecting anomalously high surface temperatures (thermal stress signatures) in crop canopies, TRISHNA will provide early warning of crop water stress and drought conditions up to 2–3 weeks before visible wilting. The data feeds into the National Crop Forecast Centre (NCFC) and Pradhan Mantri Fasal Bima Yojana (PMFBY) yield models for crop insurance.

3. Urban Heat Island Monitoring

Urban Heat Islands (UHI) — the phenomenon where urban areas are significantly warmer than surrounding rural areas due to impervious surfaces and waste heat — are a growing problem for India's cities. TRISHNA will map UHI intensity at 57 m resolution across India's 100+ smart cities, informing urban planners, climate resilience strategies, and heat action plans under the National Action Plan on Heat Stress.

4. Glacier and Cryosphere Monitoring

The Himalayan cryosphere — home to the third-largest ice mass on Earth outside the polar regions — is retreating at an accelerating rate. TRISHNA will track surface heat fluxes, glacier melt rates, and permafrost dynamics, supporting the National Mission for Sustaining the Himalayan Ecosystem (another NAPCC mission).

5. Coastal and Inland Water Quality

Sea Surface Temperature (SST) mapping within ~200 km of the coast will assist fisheries departments in identifying thermoclines and predicting fish aggregation zones, supporting India's Blue Economy framework. Inland water body temperature monitoring will track algal bloom formation, eutrophication, and water quality in rivers and reservoirs.

6. Forest Fire Detection

The TIR instrument's thermal sensitivity (<0.3 K) enables detection of sub-pixel thermal anomalies — active fire fronts before they expand to satellite-detectable sizes. This will improve India's Forest Fire Alert System managed by the Forest Survey of India (FSI).

7. Climate Model Validation

Long-term surface energy balance data from TRISHNA will validate General Circulation Models (GCMs) used by the India Meteorological Department (IMD) and climate research institutions, improving seasonal precipitation and heat wave forecasting.

Constitutional Provisions

Article 253 (Parliament's power to implement international treaties) enables the legislative and funding framework for joint international space missions. Space activities in India are not explicitly mentioned in the Seventh Schedule — they operate under residuary powers vested in Parliament (Article 248). The Indian Space Policy 2023, released by the Government of India in April 2023, formalises the framework for ISRO, IN-SPACe, NSIL, and private sector participation in India's space programme.

Legal Framework

Outer Space Treaty (OST), 1967: India is a signatory. Under OST, India bears international responsibility for national space activities (including TRISHNA) regardless of whether carried out by government or private entities.
Remote Sensing Data Policy (RSDP), 2011: India's data policy for satellite remote sensing — governs distribution and licensing of Earth observation data including from TRISHNA.
Indian Space Policy, 2023: Operational framework for ISRO-led and private-sector space activities; enables joint international missions through IN-SPACe authorisation.
Indo-French Space Cooperation Agreement: Bilateral MoU governing the TRISHNA mission's data sharing, IPR, and operational responsibilities.

Institutional Framework

ISRO (Indian Space Research Organisation): Under Department of Space; primary Indian partner for TRISHNA.
CNES (Centre National d'Études Spatiales): French national space agency; primary French partner; leads TIR instrument development.
IN-SPACe (Indian National Space Promotion and Authorisation Centre): Statutory body under Department of Space that authorises non-government entities and international collaborations.
NSIL (NewSpace India Limited): ISRO's commercial arm; may handle commercial data distribution from TRISHNA.
CEOS (Committee on Earth Observation Satellites): International coordination body of which both ISRO and CNES are members; TRISHNA is registered in CEOS's EO Handbook database.

Significance for India

TRISHNA fills a critical gap in India's Earth observation constellation: while India has excellent optical (Resourcesat), radar (RISAT), and oceanographic (OceanSat) satellites, it lacks a high-resolution, high-temporal-frequency thermal infrared satellite. The existing Landsat 8/9 (NASA/USGS) and Sentinel-3 (ESA) thermal data are too coarse (100 m and 1 km respectively) for the field-level water stress and urban heat mapping that TRISHNA delivers. TRISHNA will be one of the highest-resolution TIR satellite systems in the world.

Challenges

Data processing complexity: Atmospheric correction of TIR data (removing the confounding effect of the atmosphere on measured surface temperatures) requires sophisticated algorithms; CNES leads this component.
Launch schedule risk: The mission has already slipped from an original 2024 target to 2027; further delays could affect applications dependent on timely thermal data.
Ground truth network: India's network of automated weather stations and eddy covariance towers (for ET validation) needs expansion to fully exploit TRISHNA's data.

Way Forward

The NITI Aayog has recommended leveraging TRISHNA data for the National Water Use Efficiency Programme and for the District Agriculture Contingency Plans under the Ministry of Agriculture. The National Mission on Strategic Knowledge for Climate Change (one of NAPCC's eight missions) will use TRISHNA data for long-term climate monitoring. Once operational, TRISHNA data availability through ISRO's Bhuvan geoportal and CNES's THEIA data centre will enable India's research universities and state governments to use thermal EO data for the first time at field-scale resolution.

Possible Mains Questions

Discuss the applications of the TRISHNA satellite mission for India's water security and agricultural planning. How does it complement India's existing Earth observation satellite constellation? (GS-III, 10 marks)
Analyse the significance of the Indo-French space partnership in the context of India's space diplomacy and national development goals. (GS-II, 10 marks)

Possible Prelims MCQs

Q. TRISHNA is a joint satellite mission between India and which country? (A) Japan (B) USA (C) France (D) Germany. Answer: (C) France (ISRO + CNES)
Q. TRISHNA stands for: (A) Thermal Remote Imaging Satellite for High Natural Assessment (B) Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment (C) Terrestrial Remote Imaging Satellite for Hydrological Analysis (D) Thermal Radiation Infrared Satellite for Humidity and Nitrogen Assessment. Answer: (B)

Essay Dimensions

Space diplomacy as a force multiplier in India's bilateral relationships.
From telescope to policy: how Earth observation satellites can transform India's water governance.
Thermal sensing and the invisible crisis: mapping water stress before crops fail.
Smart cities and heat islands: using space technology to build climate-resilient urban futures.
India's place in the global Earth observation ecosystem: capabilities, gaps, and ambitions.

Interview Questions

TRISHNA provides 57 m resolution thermal data. What specific policy decisions in water management can this enable that were not possible with existing 1 km resolution satellites?
How does the TRISHNA mission reflect the "mission mode" approach to climate science that India needs?
Why is France a preferred space partner for India rather than, say, the US or China?
If you were a district agriculture officer, how would you use TRISHNA data to improve crop insurance assessments?
The Himalayan cryosphere is retreating rapidly. What specific role can thermal infrared satellites play in cryosphere monitoring?

FAQ

What is the TRISHNA satellite mission?: TRISHNA is a joint Earth observation satellite mission between ISRO (India) and CNES (France) that measures surface temperature and related parameters (evapotranspiration, water stress, urban heat) at high spatial resolution (57 m TIR, 20 m VNIR-SWIR). It is India's first dedicated thermal infrared satellite.
What is the planned launch date for TRISHNA?: The current planned launch window is October 2027, on a PSLV rocket from Sriharikarta. The TIR instrument from CNES was delivered to ISRO in 2026 for satellite integration. An earlier 2024 target slipped due to development timelines.
How is TRISHNA useful for agriculture?: TRISHNA's TIR instrument detects crop canopy temperature anomalies that indicate water stress weeks before visible crop damage. This enables early irrigation intervention, precise water resource allocation, and improved crop yield forecasting for government schemes like PMFBY.

TRISHNA Mission: ISRO-CNES Joint Thermal Infrared Satellite for Water, Agriculture, and Urban Heat Monitoring

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