ISRO on Tuesday successfully carried out a static ground test of an improved third stage of the Small Satellite Launch Vehicle (SSLV) at the Solid Motor Static Test Facility of the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh, marking a key milestone in enhancing the launch vehicle&rsquo;s performance.
The SSLV is a three-stage, all-solid launch vehicle designed to support quick turnaround launches and enable launch-on-demand capabilities, with a strong focus on industrial production. The third stage, also known as the upper stage, is responsible for imparting a velocity of nearly 4 km per second to the launch vehicle and uses a monolithic composite motor case along with a free-standing nozzle divergent to reduce inert mass.
The latest static firing validated an upgraded version of the SSLV&rsquo;s third-stage motor featuring a carbon-epoxy motor case. This design change has significantly reduced the mass of the stage, resulting in an improvement of approximately 90 kg in the payload-carrying capability of the SSLV. The stage also incorporates an improved igniter and nozzle system, making the motor more efficient and robust.
In addition, nozzle control in the upgraded stage is achieved through a fault-tolerant electro-mechanical actuation system equipped with low-power control electronics, enhancing overall reliability. The high-strength carbon filament-wound motor case was developed at the Composites Entity of the Vikram Sarabhai Space Centre, while the solid motor casting was carried out at the solid motor production facilities at Sriharikota.
ISRO said all performance parameters recorded during the 108-second test closely matched pre-test predictions. With the successful completion of this static firing, the improved SS3 motor has now been qualified for induction into future SSLV flights.
The space agency also highlighted broader capacity-building efforts undertaken this year to strengthen India&rsquo;s solid motor manufacturing ecosystem. New solid motor production facilities were commissioned at Sriharikota in July 2025 to augment production capacity. In September 2025, a second production line for ammonium perchlorate, a critical ingredient for solid propellants, was commissioned at the plant in Alwaye, effectively doubling output.
An indigenous 10-tonne vertical mixer, described as the world&rsquo;s largest solid propellant mixing equipment, was also commissioned this year at the Sriharikota centre. In parallel, the Solid Motor Production and Static Testing facilities have supported the realisation and static testing of a solid motor used for the first orbital launch of a launch vehicle developed by an Indian space start-up, underscoring growing private sector participation in the country&rsquo;s space programme.

Small Satellite Launch Vehicle (SS3) with a carbon-epoxy motor case(ISRO)

Static firing in Sriharikota validates lighter SS3 stage, boosting SSLV payload capacity

ISRO tests upgraded SSLV third stage motor

Static firing in Sriharikota validates lighter SS3 stage, boosting SSLV payload capacity

December 31, 2025 | 17:24 IST