The 43.43 metre-tall GSLV Mk III was launched from the Satish Dhawan Space Centre in Sriharikota, in Andhra Pradesh, and onboard the rocket was the 3,136-kg GSAT- 19 communication satellite. The GSAT-19 satellite was delivered to a geosynchronous transfer orbit.
The rocket is the most powerful version of the GSLV rockets developed by ISRO and features an indigenously developed cryogenic engine which provides a huge final thrust to the rocket after the initial solid and liquid fuel engine stages. GSLV Mk III will reduce India’s dependency on European rockets for launching heavy communication satellites and will help the space agency position itself as an affordable provider of space launch facilities at a time of increasing privatisation of the space launch and service business.
The cryogenic upper stage in the GSLV Mk III rocket, called the C25 engine, is an improvement on C20 cryogenic engines used in the GSLV Mk II rockets which entered operational phase in September 2016, after over 25 years of development, following the successful flight of the GSLV F05 with a 2,211-kg INSAT-3DR weather satellite.
Developed by ISRO’s Liquid Propulsion Systems Centre, the C25 cryogenic engine carries more propellant (27 tonnes versus 12.5 tonnes) and higher engine thrust (19 tonnes versus 7.5 tonnes) when compared to the C20 cryogenic upper stage successfully tested on January 5, 2014. The GSLV Mk III is intended to launch heavy satellites in the four-tonne class into geo stationary orbits — a capability ISRO lacks since the basic GSLV can carry only around 2.3 tonnes.
The C25 engine was developed indigenously by ISRO based on Russian cryogenic engines which the agency used during early phases of the development of the GSLV rockets. The L110 liquid fuel engines — an improved version of the ISRO’s Vikas solid fuel engines — used in the second stage of the GSLV Mk III rocket are one of the heaviest earth storable liquid stages ever developed by ISRO.
The cryogenic stage on the GSLV is the third stage and uses liquid hydrogen as fuel and liquid oxygen as an oxidiser. Cryogenic stage is a highly efficient rocket stage that provides more thrust for every kilogram of propellant it burns compared to solid and earth-storable liquid propellant stages. The specific impulse achievable with cryo fluids is 450 seconds compared to 300 second for other fuels.