ISRO conducts ground test of SSLV third stage at Sriharikota

ISRO has carried out a successful static test of an improved version of the third stage of SSLV at the Solid Motor Static Test Facility of Satish Dhawan Space Centre, Sriharikota in Andhra Pradesh.

According to the Indian Space Research Organisation (ISRO), the test was conducted on Tuesday.

The Small Satellite Launch Vehicle (SSLV) is a three-stage all-solid launch vehicle developed by ISRO, which is amenable to industrial production and can meet launch-on-demand with a quick turnaround time between launches, ISRO said in a statement.

"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," it added.

The space agency said the static test validated an improved version of Stage 3 of the Small Satellite Launch Vehicle (SS3) with a carbon-epoxy motor case, which has significantly reduced the mass of the stage, thereby improving the payload performance of SSLV by 90 kg.

"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 explained.

It added that the high-strength carbon filament-wound motor case was realised at the Composites Entity of Vikram Sarabhai Space Centre and the solid motor was cast at the Solid Motor production facilities at Satish Dhawan Space Centre (SDSC).

"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," the statement read.

According to ISRO, this year, multiple facilities have been commissioned in the country to enhance the capacity of realising solid motors for the space programme.

In July 2025, Solid Motor production facilities were commissioned at Sriharikota to augment the capacity.

Further, a second production line for Ammonium Perchlorate was commissioned in September 2025 at the Ammonium Perchlorate Plant at Alwaye to double the production capacity of the key ingredient required for the solid motors, the statement said.

An indigenous 10-tonne vertical mixer for the solid motor production line was commissioned this year at SDSC, which is the world's largest solid propellant mixing equipment.

The Solid Motor Production and Static Testing (SMPST) facilities at SDSC have also realised and static tested the solid motor for the first orbital launch of a launch vehicle developed by an Indian Space Start-up.