The Author is Former Director General of Information Systems and A Special Forces Veteran, Indian Army

India's first privately manufactured Polar Satellite Launch Vehicle (PSLV), being built by a consortium of Hindustan Aeronautics Limited (HAL) and Larsen and Toubro (L&T), will carry a technology demonstration satellite (TDS-1) that will test up to 35 new indigenous technologies, according to news reports of February 18, 2025. Costing $31 million, TDS-1 is a geostationary orbit technology demonstration satellite carrying payloads for the Indian Space Research Organisation (ISRO)'s Institute of Plasma Research, Gandhinagar and the CSIR-CEERI, Pilani. Set for a launch in the third quarter of 2025, this mission is not only a technological milestone but also a pioneering achievement for the country's growing private space sector; taking India on the verge of a major advancement in its space programme.

India's first privately manufactured Polar Satellite Launch Vehicle (PSLV), being built by a consortium of HAL and L&T, will carry a technology demonstration satellite (TDS-1) that will test new indigenous technologies

ISRO Chairman V. Narayanan revealed this in an exclusive interview to media and said the launch, scheduled for the third quarter of this year, will mark a milestone as the first PSLV by the private sector under a contract for five rockets. Narayanan further said, "It is called a technology demonstration satellite (TDS-1). There are 35 experimental things. Among other things, along with chemical propulsion, we are also going to use electric propulsion. We are also going to demonstrate indigenous atomic clock, quantum payloads. So, a lot of things are in store. And right now, the payload is getting realised."

Narayanan further said, "The final number of experiments, targeted at 35, will be confirmed later. In TDS-1, ISRO will test a 300 milli-Newton (300mN) electric propulsion thruster, developed at ISRO's Liquid Propulsion Systems Centre (LPSC). The new thruster is currently undergoing cycle testing. Narayanan said ISRO had earlier tried a 75mN thruster on the GSAT-9, but what will go on TDS-1 will be the first time an entirely indigenous system will be deployed. He added that the organisation had earlier developed associated components like the power processing unit, control systems and propellent tankage internally." Narayanan headed the LPSC before taking over as ISRO chairman.

This satellite is a technology test bed that will carry 35 advanced indigenous systems that will play a key role in shaping India's future in space, makes the mission highly significant

Referring to ISRO's programme for developing the Next Generation Launch Vehicle (NGLV), Narayanan said, "Our first launcher, the SLV-3, had the capability of putting around 35-40 kg to Low Earth Orbit (LEO). From that, our heaviest rocket (LVM-3) is capable of taking around 8,500 kg to LEO. Now in NGLV the lift of mass will be around 1,000 tonnes and that height of the vehicle is 93m, more than a 30-35 storied building height. The NGLV will feature three propulsive stages and two strap-on boosters. The core stage will be powered by nine LOX-methane engines, each generating 110 tonnes of thrust, with a propellant loading of 475 tonnes. The second stage will use two LOX-methane engines of the same class with 128 tonnes of propellent. The upper stage will use a LOX-hydrogen cryogenic engine (the C-32) with 32 tonnes of propellant capacity."

Narayanan said the configuration study was completed and ISRO was in the process of development of subsystems, for example engines. "The design for the 11 LOX-methane engines (nine in core stage and two in second stage) has been finalised and we are in the process of giving clearance for fabrication." Mission studies have been completed, while rocket structures and tankage designs are ongoing, he said, adding that ISRO is currently in discussions with industry partners for manufacturing while simultaneously developing test facilities.

The success of the TDS-1 mission implies application of these technologies in future interplanetary spacecraft

TDS-1 is undoubtedly a giant leap for India's private space sector particularly because it has been entirely manufactured by private industry, reflecting the nation's increasing confidence in its homegrown space capabilities. The rocket will transport TDS-1 into a sun-synchronous orbit at 747 km altitude, enabling the satellite to cover the entire Earth every 12 days, providing crucial data for multiple applications. The fact that this satellite is a technology test bed that will carry 35 advanced indigenous systems that will play a key role in shaping India's future in space, makes the mission highly significant. Its electric propulsion thruster makes this system more efficient with a longer operational lifespan than conventional chemical thrusters; making it suitable for long-duration and deep-space missions.

Since TDS-1 will also validate an indigenous atomic clock, which offers high precision and reliability, this technology will enhance India's satellite navigation systems and improve the accuracy of space-based operations. The satellite is equipped with high-resolution cameras and spectrometers, which will collect detailed imagery and environmental data; contribute to weather forecasting, disaster response, resource mapping, and scientific research, expanding India's ability to monitor and understand Earth's changing environment. Moreover, TDS-1 will test quantum communication payloads, utilising quantum mechanics principles to create highly secure, unbreakable encryption. This advancement could transform secure satellite communications, benefiting both civilian and defence applications.

Finally, the success of the TDS-1 mission implies application of these technologies in future interplanetary spacecraft. Its success will also validate the private sector's role in building and launching space vehicles, paving the way for even more ambitious partnerships in the future.