ISRO to Launch First Fully Electric-Propelled Satellite in December
As 2024 comes to a close, India is gearing up to test its first indigenously developed electric propulsion system (EPS) in space. This milestone launch will take place in December with the release of the Technology Demonstrator Satellite (TDS-01), marking a major leap for the Indian Space Research Organisation (ISRO). The electric propulsion system is a game-changer, allowing for lighter, more efficient satellites and marking a significant shift in how future satellites will be powered and maneuvered in orbit.
During the Sardar Patel Lecture at Akashvani, ISRO Chairman S. Somanath shed light on the ambitious plans for the TDS-01. This will be the first Indian satellite to use a homegrown EPS, promising a lighter design and enhanced satellite capabilities. Traditional satellites rely heavily on chemical propulsion systems that require large amounts of liquid fuel, often taking up half of the satellite's total weight. For instance, a typical four-ton satellite carries around two to 2.5 tons of liquid fuel, which is primarily used for fine-tuning the satellite’s position in orbit, counteracting atmospheric drag, and dealing with gravitational pulls from the sun and moon.
With electric propulsion, however, the need for heavy liquid fuel drastically drops to just around 200 kilograms. This reduction is possible because EPS does not rely on chemical combustion but instead ionizes a gas—such as Argon—using solar power. Once ionized, the gas produces a continuous stream of low-thrust propulsion, which, though slower, can significantly extend a satellite's operational lifespan and allow for lighter and more compact designs.
This shift to electric propulsion technology is strategic, especially as ISRO aims to maximize payload capacity without adding excess weight. As Somanath explained, when the size of the fuel tank reduces, so does the size of other peripheral components, creating a “cumulative effect.” The result is a satellite that weighs about two tons but has the functional power of a four-ton satellite, representing a highly efficient design without compromising on performance.
However, the benefits of EPS come with certain trade-offs. The primary limitation of electric propulsion is its low thrust, which means that satellites take longer to reach their target orbit. Somanath noted that while a satellite using chemical propulsion can reach a geostationary orbit within a week, a satellite powered by EPS would take close to three months. Yet, this extended timeframe is a small compromise given the extended lifespan and increased operational efficiency the system offers.
This isn’t ISRO’s first encounter with electric propulsion. In 2017, the South Asia Satellite, GSAT-9, became ISRO’s first mission to utilize EPS, though the components for that system were imported from Russia. This December’s launch will mark the first time an Indian-made EPS will be used, underscoring the progress in indigenous technology development. Additionally, the TDS-01 will feature another innovation: indigenously produced traveling wave tube amplifiers (TWTAs), which are essential for the satellite’s communication and remote sensing capabilities.
Beyond the TDS-01 launch, ISRO has its sights set on further high-stakes projects. One of these is the NASA-ISRO Synthetic Aperture Radar (NISAR) mission, set to launch in February. A joint project between NASA and ISRO, the NISAR satellite is designed to provide advanced Earth observation capabilities, with applications ranging from monitoring natural hazards to tracking climate change effects. Recently, NASA delivered the radar antenna reflector—a crucial component of the satellite—from its Jet Propulsion Laboratory in California to ISRO’s Bangalore facility. The integration process will take approximately two months, with the launch slated for early 2025.
As ISRO moves forward, the December launch of the TDS-01 will stand as a hallmark of India’s growing expertise in cutting-edge space technology. The shift toward electric propulsion, spearheaded by the development of the EPS, positions India as a formidable player in the field of space exploration. This step not only reflects ISRO's technical advancements but also highlights the organization’s commitment to building sustainable and innovative space systems that pave the way for future explorations and missions.
