The Indian Space Research Organisation (ISRO) has successfully conducted a static test of an improved version of the 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.
According to ISRO, the test was carried out on Tuesday.
In a statement, the space agency said the SSLV is a three-stage, all-solid launch vehicle developed to support industrial production and enable launch-on-demand missions with a quick turnaround between launches.
Explaining the role of the upgraded stage, ISRO said, "The upper stage or third stage solid motor delivers as high as 4 km/s velocity to the launch vehicle and employs a monolithic composite motor case and a free-standing nozzle divergent to limit the stage inert mass."
ISRO said the static test validated an improved version of Stage 3 of the Small Satellite Launch Vehicle (SS3), which features a carbon-epoxy motor case. This enhancement has led to a significant reduction in the stage’s mass, improving the payload capability of the SSLV by 90 kg.
Detailing further upgrades, the agency stated, "The stage also features an improved design for the igniter and nozzle system, making the system more efficient and robust. The nozzle control is implemented through a fault-tolerant electro-mechanical actuation system with low-power control electronics."
ISRO added that the high-strength carbon filament-wound motor case was realised 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 the Satish Dhawan Space Centre (SDSC).
Summarising the test outcome, the statement noted, "All the measured parameters are observed close to predictions over the test duration of 108 seconds. With this successful static firing test, the improved version of the SS3 motor is qualified for induction in flight."
ISRO also highlighted that several facilities have been commissioned across the country this year to enhance the capacity for solid motor production under the space programme.
In July 2025, new solid motor production facilities were commissioned at Sriharikota to augment manufacturing capacity. Additionally, a second production line for Ammonium Perchlorate was commissioned in September 2025 at the Ammonium Perchlorate Plant in Alwaye, doubling the production capacity of a critical ingredient used in solid motors.
The space agency further said that an indigenous 10-tonne vertical mixer for the solid motor production line was commissioned this year at SDSC, describing it as the world’s largest solid propellant mixing equipment.
ISRO added that the Solid Motor Production and Static Testing (SMPST) facilities at SDSC have also successfully realised and static-tested the solid motor used for the first orbital launch of a launch vehicle developed by an Indian space start-up.