ISRO Successfully Tests Upgraded SSLV Third Stage

ISRO Clears Upgraded SSLV Stage for Future Missions

The Indian Space Research Organisation (ISRO) has achieved a significant milestone in its small satellite launch programme with the successful ground test of the upgraded third stage (SS3) of the Small Satellite Launch Vehicle (SSLV) . Conducted on December 30, 2025 , the test validates critical design upgrades and clears the stage for induction into upcoming SSLV missions, reinforcing India’s launch-on-demand capability.

Static Firing at Sriharikota

The static ground firing of the improved SS3 motor was carried out at the Solid Motor Static Test Facility of the Satish Dhawan Space Centre (SDSC), Sriharikota . The motor was fired for 108 seconds , during which all parameters—including thrust, chamber pressure and burn profile—closely matched pre-test simulations. As the uppermost solid stage of SSLV, SS3 plays a vital role in imparting the final velocity required to inject satellites into orbit.

Design Enhancements and Payload Advantage

A key upgrade in the new SS3 is the adoption of a carbon-epoxy composite motor case , replacing earlier designs. This significantly reduces inert mass and results in a payload gain of nearly 90 kg for the SSLV. The third stage alone provides velocities of up to 4 km per second . Improvements to the igniter and nozzle systems further enhance efficiency, robustness and operational margins.

Advanced Monitoring and Control

The test employed around 233 sensors to monitor pressure, temperature, vibration, thrust and actuator performance. Nozzle steering is achieved through a fault-tolerant electro-mechanical actuation system , supported by low-power control electronics, ensuring high reliability for future missions.

Strengthening Indigenous Capacity

The composite motor case was developed at the Vikram Sarabhai Space Centre , while solid propellant casting was completed at SDSC. This test aligns with ISRO’s broader expansion of solid motor manufacturing infrastructure, boosting self-reliance and supporting both national missions and private space enterprises.

Important Facts for Exams

• SSLV is a three-stage, all-solid launch vehicle

• SS3 provides up to 4 km/s velocity

• Composite motor cases increase payload capacity

• Sriharikota hosts India’s main launch complex