Why mission TRISHNA has an edge over other similar missions?

The mission is set to last for five years, with a launch date targeted for 2025

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At a time when climate change and managing water resources are major global concerns, the importance of advanced technology for monitoring and data collection is greater than ever. One notable effort in this field is the partnership between the Indian Space Research Organisation (ISRO) and the French space agency, Centre National d'Études Spatiales (CNES). Together, they have developed an innovative thermal imaging satellite called TRISHNA. The satellite, weighing approximately 770 kg, is expected to orbit at an altitude of 761 km in a sun-synchronous orbit, with a local crossing time (descending node) of 1 p.m., ensuring consistent lighting conditions for its observations. The mission is set to last for five years, with a launch date targeted for 2025. 

This joint  mission aims to deliver high-quality thermal images to help us better understand and tackle environmental issues, especially those connected to climate change and water management. TRISHNA, short for Thermal infra Red Imaging Satellite for High-resolution Natural resource Assessment, is built to provide exceptional details about the Earth's land and water temperatures. These measurements are crucial for various uses, such as farming strategies, tracking urban heat, and managing disasters. 

“The satellite’s advanced technology also addresses food security challenges by focusing on the impacts of human-induced climate change and improving water resource management through evapotranspiration monitoring. TRISHNA aims to enhance our understanding significantly and offer more accurate data for scientists, policymakers, and environmentalists around the world,” explained space expert Girish Linganna. 

Evapotranspiration is the process by which water is transferred from the land to the atmosphere through two main mechanisms: evaporation from soil and water surfaces, and transpiration from plants. It's a crucial part of the water cycle and helps in understanding water use and availability, especially in agriculture and climate studies. 

The TRISHNA satellite comes with two main payloads—Thermal Infra-Red (TIR) Payload provided by CNES which features a four-channel long-wave infrared imaging sensor capable of high-resolution surface temperature and emissivity mapping. Then the second payload Visible - Near Infra-Red - Short Wave Infra-Red (VNIR-SWIR) Payload developed by ISRO which includes seven spectral bands designed for detailed mapping of surface reflectance in VSWIR bands (Visible, Short-Wave Infrared) and will help generate important biophysical and radiation budget variables. 

The satellite will orbit the Earth in a sun-synchronous path at an altitude of 761 km, crossing the equator at 12:30 PM local time. This orbit allows the satellite to capture images with a spatial resolution of 57 meters for land and coastal areas, and 1 km for ocean and polar regions. The mission is planned to last for 5 years. 

“Thermal imaging satellites are essential for monitoring Earth's climate, water resources, and environmental changes. They use thermal sensors to detect heat variations on the Earth's surface, aiding studies on urban heat islands, agricultural health, and forest fire detection,” added Linganna. 

There have been other similar programs such as the USA's Landsat, Europe's Sentinel-3, and China's Gaofen series. The Landsat program, overseen by NASA and USGS, has been providing continuous Earth observation data since 1972. This program is essential for monitoring environmental changes, land use, and natural resources with high-quality satellite images. The latest data from the Landsat program, featuring Landsat 9, is freely accessible to the public. Launched on September 27, 2021, Lands at 9 continues the work of previous satellites by offering detailed images of Earth. This data is vital for tracking land resources and understanding environmental changes. One can find this data on platforms like EarthExplorer, LandsatLook, and GloVis. 

On the other hand Sentinel-3(Europe) is a key part of the Copernicus Programme, which helps monitor our oceans and land. There are two satellites, Sentinel-3A and Sentinel-3B, that provide detailed images and measurements. These satellites are useful for studying the oceans, water bodies, and land, and they play an important role in climate change research and protecting the environment. Recently, there have been some issues with the quality of  Sea and Land Surface Temperature Radiometer (SLSTR)products due to satellite maneuvers, and the security system has been upgraded. 

On the other hand China's Gaofen series is part of the China High-resolution Earth Observation System (CHEOS). The most recent satellite, Gaofen 12 (03), was launched in 2022. It orbits close to the poles and uses microwave remote sensing technology. This satellite helps improve land surveys, urban planning, and disaster relief efforts. Each of these programs contributes unique capabilities and data sets, advancing scientific understanding and practical applications in agriculture, water management, and disaster response. 

The TRISHNA satellite, a collaboration between ISRO and CNES, represents a significant advancement in thermal imaging for climate and water monitoring. Compared to other prominent satellites, Trishna's cutting-edge technology captures high-resolution thermal data with exceptional precision. Landsat's historical data is invaluable, but TRISHNA offers higher resolution and sensitivity. Sentinel-3 excels in marine and coastal monitoring, while TRISHNA is tailored for terrestrial applications. Gaofen-5 provides detailed data on air pollution and water quality, yet TRISHNA’s focus on climate and water monitoring offers more targeted thermal data. TRISHNA’s frequent revisits and high temporal resolution enable near real-time monitoring of climatic and hydrological phenomena, enhancing our ability to track local and global climate patterns,” explained Linganna. 

The ISRO-CNES collaboration on TRISHNA highlights the potential of international cooperation in addressing global challenges like climate change and water resource management. TRISHNA, with its advanced thermal imaging technology, complements existing systems by providing higher resolution data and more frequent revisit times, enhancing global environmental monitoring. Its high spatial resolution and superior thermal sensitivity place it at the forefront of thermal imaging satellites. TRISHNA's data will support applications such as agricultural planning, urban heat island analysis, and climate change studies, playing a critical role in informing policy decisions and fostering sustainable development. 

“TRISHNA's technical prowess lies in its advanced payloads. The Thermal Infra-Red (TIR) payload, provided by CNES, features a four-channel long-wave infrared imaging sensor capable of high-resolution surface temperature and emissivity mapping. The Visible - Near Infra-Red - Short Wave Infra-Red (VNIR-SWIR) payload, developed by ISRO, includes seven spectral bands designed for detailed mapping of surface reflectance of VSWIR bands to generate important biophysical and radiation budget variables,” said Srimathy Kesan, founder and CEO of Space Kidz India, which is into design, fabrication and launch of small satellites, spacecraft and ground systems. 

This expert further says that when compared to other thermal imaging satellites globally, TRISHNA stands out for its high spatial and temporal resolution. “If one compares it with the British company SatVu's HOTSAT-1 satellite, which also focuses on high-resolution thermal imaging, captures thermal images from space revealing the planet’s surface temperature in great detail. However, HOTSAT-1's resolution is down to 33 feet, which, while impressive, does not match TRISHNA's ambition to achieve a resolution better than 100 meters with frequent revisits several times a week,” added Kesan. 

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