India's first home-grown electric propulsion satellite to be launched in Dec: Isro chief

NEW DELHI: To make its satellites lighter in future, Isro is going to launch its first home-grown electric propulsion-led spacecraft in Dec, space agency chairman S Somanath announced while also specifying new deadlines for its upcoming key missions like Gaganyaan, Chandrayaan-4 and-5, and Indo-US NISAR satellite project.

Delivering the Sardar Patel Memorial Lecture at Akashvani, Somanath said Technology Demonstrator Satellite (TDS-1), which will be steered in space to its desired orbit with electric propulsion rather than fuel-run thrusters, is ready. “TDS-1 and Isro's first spacecraft docking experiment (SPADEX), which will help in setting up India's own space station in future, are ready and will be launched in Dec.”

"Electric propulsion system (EPS) will bring down the overall mass of a satellite as chemical fuel is not required in bulk. EPS uses energy of the Sun to move a satellite from the launch orbit to a geostationary orbit. It is a very interesting technology," Somanath explained.

A four-tonne communication satellite carries more than two tonnes of liquid fuel, which is used to fire thrusters to steer the satellite in space. But in case of electric propulsion, fuel requirement reduces to just 200 kg. As fuel mass is reduced, the electric propulsion system-based satellite will not weigh more than two tonnes but will still have the power of a 4-tonne satellite. The propellant gases in the electric propulsion system (EPS) such as Argon as fuel are ionised using solar power.

The EPS was first used to power the South Asia Satellite — GSAT-9 — launched by Isro in May 2017. However, that EPS was entirely imported from Russia.

The Isro chairman also informed that India has its own navigation system NavIC under which nine navigation satellites have been launched till now. These satellites have been using the L5 band that is largely restricted for strategic services by the armed forces. “However, now we are introducing L1 band in satellites that will allow civilians to easily access our own navigation system in their mobiles. Our NaVIC is much more accurate than other navigation systems. We are going to launch five more satellites with L1 band,” Somanath said.

Sharing specific deadlines for its upcoming key missions, Somanath said the Gaganyaan manned mission is likely to be launched in 2026, the lunar sample return mission called Chandrayaan-4 will be carried out in 2028, and the Indo-US joint space mission is scheduled to be carried out next year.

About the fifth lunar mission with Japanese space agency JAXA, originally named LUPEX and now rechristened Chandrayaan-5, the new deadline for the mission is likely to be after 2028, Somanath said.

On the Nasa-Isro Synthetic Aperture Radar (NISAR) satellite, which is considered to be the world’s most expensive earth imaging satellite, Somanath said the work on the radar antenna reflector was complete and the crucial component was flown from Nasa's Jet Propulsion Laboratory in California to Isro's spacecraft integration and test facility in Bengaluru. Somanath said the integration of the radar antenna reflector with the satellite will take about two months. "We will schedule it for launch in Feb," the Isro chairman said.

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