Discuss the relevance of thermal infrared Earth observation missions such as TRISHNA for India's water security and climate adaptation.

Thermal infrared (TIR) sensors measure land surface temperature. That shows how much water soil and plants are losing, often before a crop visibly wilts. TRISHNA (Thermal Infra-Red Imaging Satellite for High-resolution Natural Resource Assessment) will be the third joint ISRO–CNES satellite, after Megha-Tropiques and SARAL [4]. It will give 57 m thermal resolution over land [1], making heat data a practical tool for managing water and adapting to climate change.

Relevance for water security

• Crop water stress and evapotranspiration: mapping water lost from soil and plants lets farmers irrigate by need rather than by calendar [1]. This matters for an agriculture-dependent, water-stressed country.
• Drought monitoring: rising surface temperature shows moisture stress before crop damage appears, which allows earlier relief planning [1].
• Glaciers and snow-melt: tracking melt in Himalayan catchments improves forecasts of river flow [1].
• Coastal water quality: TRISHNA will also monitor coastal waters [1].
• Continuity: it builds on Megha-Tropiques (2011), the Indo-French mission that studied the tropical water cycle [2].

Relevance for climate adaptation

• Urban heat islands: 57 m pixels can pick out hot spots at the neighbourhood level. This helps target heat action plans, tree cover and cool roofs [1].
• Hazards: it can detect sub-surface fires and volcanic activity [1].
• Combined sensing: the CNES thermal payload and the ISRO VNIR-SWIR optical payload fly together in a 761 km sun-synchronous orbit [1]. Temperature and vegetation condition are therefore captured in the same pass.
• Oceans: 1 km coverage over oceans and polar regions [1] supports ocean science, which both countries list as an area of cooperation [4].

Limitations

• Technology dependence: the key thermal instrument is French, and India builds only the optical sensor [1].
• Uptake gap: the data helps only if state agriculture and water departments can use it. Outreach is just starting, with a Water Cycle and TRISHNA event planned in Bengaluru for October 2026 [4].
• Timeline and physics: the payload is still being built (progress was reviewed at Airbus in September 2026 [3]), and thermal sensors cannot see through monsoon cloud.

Thermal missions like TRISHNA turn heat signals into usable information on water and climate risk. To get full value, India should feed the data into state irrigation advisories, drought declarations and city heat action plans. It should also build its own thermal sensors over time. Used this way, TRISHNA directly supports SDG 6 (clean water) and SDG 13 (climate action).