ISRO conducts static fire test of upgraded SSLV third stage

The Indian Space Research Organisation (ISRO) has successfully carried out a static fire 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 (SDSC), Sriharikota, Andhra Pradesh.

According to ISRO, the test was conducted on December 30 and validated the upgraded third stage, known as SS3, marking a key milestone towards enhancing the payload capability and reliability of the SSLV programme.

The SSLV is a three-stage, all-solid launch vehicle developed to provide cost-effective and launch-on-demand services with minimal turnaround time. The third stage plays a crucial role by delivering nearly 4 km per second velocity to the launch vehicle.

ISRO said the improved SS3 stage features a high-strength carbon-epoxy motor case , which has significantly reduced the mass of the stage, resulting in an increase of about 90 kg in payload capacity for the SSLV. The upgraded stage also incorporates an improved igniter and nozzle design, 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,” the space agency said in a statement.

The static test lasted 108 seconds , during which all performance parameters closely matched pre-test predictions. With this successful test, the improved SS3 motor has been qualified for induction into future flight missions, ISRO added.

The carbon-epoxy 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 of SDSC.

ISRO also highlighted that multiple infrastructure upgrades were commissioned in 2025 to enhance the country’s solid motor production capacity. In July this year, new solid motor production facilities were commissioned at Sriharikota. A second production line for Ammonium Perchlorate, a key ingredient for solid propellants, was commissioned in September at the Ammonium Perchlorate Plant at Alwaye, doubling production capacity.

In addition, an indigenous 10-tonne vertical mixer , the world’s largest solid propellant mixing equipment, was commissioned at SDSC. The Solid Motor Production and Static Testing facilities at Sriharikota have also supported the realisation and testing of solid motors for the first orbital launch of a launch vehicle developed by an Indian space start-up.

ISRO has not yet announced the launch schedule for the SSLV mission incorporating the upgraded third stage.