Current Affairs · · Prelims · Science & Technology

TRISHNA satellite enters advanced development stage ahead of planned launch

The Indo-French TRISHNA satellite is in an advanced development stage, with an ISRO official estimating launch readiness within 12–16 months from October 2026. Jointly developed by ISRO and CNES, it will combine thermal and optical imaging to monitor crop water stress, surface temperature and natural resources. Its launch date is not yet confirmed.

Event date:

REq1
  1. Context1 / 5
    • The India–France TRISHNA Earth-observation satellite is at an advanced stage of development. On 11 October 2026, an ISRO official said it could be ready for launch in 12–16 months.
    • TRISHNA stands for Thermal Infra-Red Imaging Satellite for High-resolution Natural Resource Assessment.
    • It is a joint mission of the Indian Space Research Organisation (ISRO) and France’s space agency, Centre National d’Études Spatiales (CNES).
    • Its instruments aim to monitor land-surface temperature, crop water stress and natural resources from space.
    • Launch status: The 12–16-month window is an estimate. CNES lists a planned 2027 launch; the spacecraft has not launched.
  2. Key highlights2 / 5

    TRISHNA's planned observing system combines thermal imaging with visible and short-wave infrared measurements.

    FeaturePlanned specification
    Mission typeEarth observation
    Launch vehiclePolar Satellite Launch Vehicle (PSLV)
    OrbitSun-synchronous, about 761 km above Earth
    Camera resolutionAbout 57–90 m, depending on viewing angle
    Standard product resolutionAbout 60 m; different from camera resolution
    Revisit at the equatorAbout 3 days between observations
    Designed operational life5 years

    Two planned payloads

    • Thermal Infra-Red (TIR), provided by CNES: Four long-wave infrared channels to map surface temperature and emissivity (how effectively a surface emits thermal radiation).
    • Visible–Near Infra-Red–Short Wave Infra-Red (VNIR-SWIR), developed by ISRO: Seven spectral bands to observe reflected light and help map vegetation and surface conditions.
    • Together, their measurements are intended to improve estimates of water and energy exchanges at Earth's surface.
  3. Note3 / 5

    Applications of TRISHNA

    Agriculture and water

    • Crop water stress: Plants may become warmer when low water availability reduces transpiration and evaporative cooling.
    • Evapotranspiration: Surface temperature and optical measurements can help estimate water loss and guide more efficient irrigation.
    • Water bodies: Temperature patterns can help study conditions in lakes, rivers and coastal waters.

    Environment and other uses

    • Urban heat islands: Map hotter built-up areas to support urban planning.
    • Cryosphere and climate: Monitor snowmelt, glacier-related changes, drought and surface temperature patterns.
    • Other heat signals: Investigate possible subsurface fires, volcanic thermal anomalies and geothermal resources.

    These are intended applications. Their performance has not yet been demonstrated in orbit.

  4. Key concepts4 / 5

    1. Thermal infrared remote sensing

    Detects heat radiation emitted by a surface to estimate its temperature without touching it.

    2. Evapotranspiration

    The combined loss of water by evaporation from soil or water and transpiration from plants.

    3. Spatial and temporal resolution

    Spatial resolution describes the size of details that can be distinguished; temporal resolution describes how often an area is observed.

    4. Sun-synchronous orbit

    A near-polar orbit that allows observations of a location at nearly the same local solar time, making repeated images easier to compare.

    Prelims distinction: Thermal infrared instruments mainly measure emitted radiation; visible and near-infrared instruments mainly measure reflected sunlight.

  5. Note5 / 5

    India–France space cooperation

    TRISHNA will build on earlier India–France cooperation in Earth observation.

    Joint missionLaunch yearMain purpose
    Megha-Tropiques2011Tropical atmosphere, water cycle and monsoon-related climate studies
    SARAL2013Ocean monitoring through radar altimetry (measuring sea-surface height)
    TRISHNAPlannedSurface temperature, water stress and natural resource assessment
    • The partnership brings together Indian optical imaging and French thermal infrared technology.
    • The planned data could help scientists and public agencies manage irrigation, water resources and climate-related risks.
    • Final takeaway: TRISHNA is a planned Earth-observation mission, not a navigation satellite; its proposed measurements have not yet been collected in orbit.

Sources

Syllabus

PaperSubjectSub-topic
PrelimsScience & TechnologyTRISHNA mission, ISRO–CNES cooperation, Earth-observation satellite payloads and remote sensing
GS3Science & TechnologySpace technology and its applications in crop water stress, agriculture, climate and resource monitoring

Topics

Agriculture and EnvironmentClimate ChangeInternational Relations and Current AffairsSpace Technology

Practice questions

  1. With reference to the TRISHNA satellite, consider the following statements: 1. It is a joint Earth-observation mission of India and France. 2. Its thermal infrared payload is being developed by CNES. 3. Its primary objective is to provide satellite-based navigation services. Which of the statements given above are correct?

    1. 1 and 2 only
    2. 2 and 3 only
    3. 1 and 3 only
    4. 1, 2 and 3
    Show answer

    Answer: A. Statements 1 and 2 are correct: ISRO and CNES are developing an Earth-observation satellite, and CNES supplies the thermal infrared payload. Statement 3 is incorrect: TRISHNA is intended to study temperature, water stress and natural resources, not navigation.

    Difficulty: easy · statement

  2. Consider the following statements about thermal infrared remote sensing: 1. It can help measure the temperature of Earth’s surface. 2. It can support monitoring of crop water stress. 3. It operates exclusively by measuring visible sunlight reflected from Earth’s surface. Which of the statements given above are correct?

    1. 1 only
    2. 1 and 2 only
    3. 2 and 3 only
    4. 1, 2 and 3
    Show answer

    Answer: B. Statements 1 and 2 are correct. Thermal sensors detect emitted heat radiation, which helps estimate surface temperature and crop water stress. Statement 3 is incorrect: visible-light reflection is a different measurement from thermal emission.

    Difficulty: medium · statement

  3. Consider the following pairs of Indo-French satellite missions and their objectives: 1. Megha-Tropiques — Tropical atmosphere and climate 2. SARAL — Ocean surface monitoring by altimetry 3. TRISHNA — Thermal infrared observation for natural resource assessment How many of the above pairs are correctly matched?

    1. Only one
    2. Only two
    3. All three
    4. None
    Show answer

    Answer: C. All three pairs are correct. Megha-Tropiques was launched in 2011 to study the tropical atmosphere and water cycle; SARAL was launched in 2013 to study the oceans using altimetry; TRISHNA is planned to observe surface temperature and resource conditions.

    Difficulty: medium · statement

Mains practice

Answer-writing practice on this article. Attempt it first, then open the hints.

  1. GS3 · 150 words

    Explain how thermal infrared satellite technology can improve agricultural water management and climate monitoring. Discuss with reference to the TRISHNA mission.

    Show hints
    1. Explain how emitted thermal radiation helps estimate land-surface temperatures and vegetation water stress.
    2. Define evapotranspiration and link thermal measurements to more efficient irrigation and water budgeting.
    3. Describe the combined value of CNES thermal imaging and ISRO visible-to-short-wave infrared observations.
    4. Discuss potential uses for drought, urban heat, snowmelt and inland or coastal water monitoring.
    5. Mention India–France cooperation and distinguish planned capabilities from operational results.