TRISHNA Mission
The TRISHNA (Thermal Infra-Red Imaging Satellite for High-resolution Natural Resource Assessment) mission represents the third major Earth-observation joint venture between India's ISRO and France's CNES, building upon the legacy of Megha-Tropiques (2011) and SARAL (2013).
1. Key Technical & Orbital Parameters
Collaborating Agencies: ISRO (India) and CNES (France).
Orbit Type: Sun-Synchronous Polar Orbit (SSO).
Altitude: Approximately 761 km.
Equatorial Crossing Time (LTDN): ~12:30 PM to 1:00 PM local solar time (chosen intentionally to coincide with peak thermal contrast and maximum daily transpiration stress).
Spatial Resolution: 57 metres for land and coastal zones; ~1 km for open oceans and polar regions.
Revisit Frequency: ~3-day repeat cycle at the equator.
Designed Operational Lifespan: 5 years.
2. Dual Payloads & Workshare Distribution
| Component / Payload | Developed By | Spectral Bands & Core Specifications | Primary Functions |
| Thermal Infra-Red (TIR) | CNES (France) | 4-channel Long-Wave Infrared (LWIR) sensor | Maps absolute Land Surface Temperature (LST), surface emissivity, and thermal anomalies. |
| VNIR–SWIR | ISRO (India) | 7 spectral bands (Visible, Near-Infrared, and Short-Wave Infrared) | Measures vegetation health (NDVI), surface albedo, soil moisture, and atmospheric corrections. |
| Bus & Launch Vehicle | ISRO (India) | Modified IMS-2 / standard Earth observation satellite platform; launch via PSLV. | Spacecraft bus integration, orbital delivery, and primary ground station telemetry. |
3. Scientific Working Principle: Detecting Water Stress
Plant undergoes water deficiency
Conventional optical remote sensing only reveals drought when vegetation browns or wilts (structural damage already occurred). TRISHNA captures evapotranspiration (ET) drop and surface energy balance shifts at the early physiological stage, giving agronomists actionable lead time.
4. Primary Applications Across UPSC Syllabus Themes
A. GS Paper III: Agriculture & Water Resource Management
Precision Irrigation: Quantifies real-time crop water consumption, enabling demand-based irrigation rather than uniform flood irrigation.
Drought Early Warning: Facilitates near real-time tracking of agricultural drought and soil moisture deficits.
Aquifer & Groundwater Studies: Monitors inland water bodies, reservoir capacities, and submarine groundwater discharge along coastal belts.
B. GS Paper III: Environment, Climate & Urban Planning
Urban Heat Islands (UHIs): High 57 m resolution pinpoints micro-level urban heat traps, aiding thermal zoning, cool-roof deployments, and sustainable urban morphology.
Glaciology & Cryosphere Dynamics: Tracks permafrost thaw, snow-melt runoff, and early warning vectors for Glacial Lake Outburst Floods (GLOFs) in the Himalayas.
Subsurface Fire & Geothermal Mapping: Detects coal seam fires (e.g., Jharia), peatland burn risks, and geothermal energy gradients.
C. GS Paper II: Bilateral Relations (India–France Strategic Partnership)
Highlights the mature civil space pillar of the Indo-French bilateral alliance:
Megha-Tropiques (2011): Tropical water cycle and climate studies.
SARAL (2013): Oceanography and sea-surface altimetry using ARGOS and ALTIKa.
TRISHNA: High-resolution terrestrial thermal imaging and global climate action.
Prelims Quick-Revision Pointers
Target SDGs: Directly maps into SDG 2 (Zero Hunger), SDG 6 (Clean Water & Sanitation), and SDG 13 (Climate Action).
Key Global Linkage: Feeds data into GEOGLAM (G20 Global Agricultural Monitoring Initiative) and global Essential Climate Variables (ECVs) databases.
Contrast with NISAR: While NISAR (NASA-ISRO) utilizes dual-band L-band & S-band Synthetic Aperture Radar (SAR) to measure ground deformation and biomass structure, TRISHNA relies on Thermal Infrared and optical sensors to track surface temperature and water cycles.