On January 28, 2021, ISRO's UR Rao Satellite Centre (URSC) issued a call for proposals outlining a three-phase plan to create a 100-Watt Radioisotope Thermoelectric Generator (RTG). The UR Rao Satellite Centre is ISRO's primary hub for the design, development, fabrication, and testing of domestically produced satellites. These generators will serve the dual purpose of power generation and thermal regulation for a variety of space missions.
According to sources, ISRO is now collaborating with the Bhabha Atomic Research Center (BARC) to develop a cutting-edge nuclear-powered engine for deep space missions.
While chemical engines are suitable for satellite thrusters, they are inadequate for interplanetary missions due to fuel constraints and lack of solar power at great distances.
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To overcome these limitations, ISRO and BARC are jointly working on nuclear-powered engines, which promise greater efficiency and endurance for spacecraft traveling long distances.
The project focuses on creating Radio Thermoelectric Generators (RTGs), which utilises the heat released by decaying radioactive materials like Plutonium-238, Strontium-90 and Curium-244.
The conventional structure of an RTG is notably uncomplicated, comprising two essential components: radioactively decaying fuel and an extensive array of thermocouples, which facilitate the conversion of heat into electrical energy. The fuel is situated behind a layer of thermal insulation, while the thermocouples are organised in modules that span the sides of the RTG. Please refer to the accompanying image for visual clarification.
The generated heat is passed to a thermocouple—a material that develops voltage when subjected to a temperature gradient (Seebeck Effect). This voltage is used to charge batteries, providing power to the satellite.
Unlike solar panels, RTGs are not dependent on solar proximity or planetary alignment. This feature minimises the constraints of launch windows, offering greater flexibility for mission planning.
Reportedly, ISRO aims to first develop a 5W RTG, which would provide a significant power source for deep space missions.
The concept of RTGs is not new. Renowned US spacecraft like Voyager, Cassini, and Curiosity have successfully utilised RTGs for their power needs.NASA’s Mars rover, known as Perseverance, is also fuelled by radioisotope power system.
ISRO's ambitious project holds the potential to revolutionise India's deep space exploration capabilities, opening doors to ambitious interplanetary missions that were once limited by energy constraints.
Undertaking an ambitious trajectory, ISRO envisions the establishment of a space station and the inaugural Indian human space flight mission, Gaganyaan. This blueprint also encompasses the debut of Aditya L-1, the nation's primary solar observatory, the launch of XPoSat, the second Indian space telescope, and the missions of Mangalyaan-2 to Mars. ISRO has, thus, embarked on a monumental journey to venture into distant and demanding frontiers.