Isro Conducts Ground Test For SSLV Third Stage
The test was held at the solid motor static test facility at the Satish Dhawan Space Centre, Sriharikota
Nellore: Isro carried out a successful static test to an improved version of the third stage (SS3) Small Satellite Launch Vehicle (SSLV) on December 30.
The test was held at the solid motor static test facility at the Satish Dhawan Space Centre, Sriharikota, Isro announced on Wednesday.
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 quick turn-around time between launches. 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.
The static test validated an improved version of the SS3 stage with a carbon-epoxy motor case, which has significantly reduced the mass of the stage, thereby improving the payload performance of SSLV by 90kg.
The stage also features an improved design for the igniter and nozzle system, making it more efficient and robust. The nozzle control is implemented through a fault-tolerant electro-mechanical actuation device with low power control electronics.
The high-strength carbon filament wound motor case was realized at the composite entity of Vikram Sarabhai Space Centre, Isro; and the solid motor was cast at its production facilities in the Satish Dhawan Space Centre, Isro.
The motor was instrumented with around 233 measurements to capture parameters namely pressure, thrust, temperature, vibration and control electronics and actuators parameters.
All the measured parameters are observed close to predictions over the test duration of 108 seconds. With this successful static test firing test, the improved version of SS3 motor is qualified for induction in flight.
An Isro release said that this year, multiple facilities have been commissioned in the country to enhance the capacity of realizing solid motors for the space programme. In July 2025, solid motor production facilities were commissioned at Sriharikota for augmenting the capacity.
A second production line for ammonium perchlorate was commissioned in September last at the ammonium perchlorate plant in Alwaye to double the production capacity of ammonium perchlorate required for the processing of solid motors.
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 & static testing facilities at SDSC have also realized and static- tested the solid motor for the first orbital launch of a launch vehicle developed by an Indian space start-up, the release added.
