About the Launch Vehicle

The Geosynchronous Satellite Launch Vehicle was primarily developed to launch INSAT class of satellites into Geosynchronous Transfer Orbits. GSLV is being used for launching GSAT series of satellites. GSLV is a three stage launcher that uses one solid rocket motor stage, one Earth storable liquid stage and one cryogenic stage. The most recent flight of GSLV, the GSLV-D5, placed GSAT-14 into its planned orbit and marked the first successful flight of the indigenous cryogenic stage. Earlier, GSLV had launched various communication satellites among which EDUSAT is notable, being India's first satellite built exclusively to serve the educational sector through satellite based distance education.

Vehicle Specifications

Height: 49.13 m
Number of Stages: 3
Lift Off Mass: 414.75 tonnes
First Flight: April 18, 2001
At a diameter of 3.4 m, the payload fairing of GSLV is wider than the rest of the launcher. The fairing provides aerodynamic efficiency and shields the payload from mechanical damage during the atmospheric phase of flight.
The cryogenic upper stage of GSLV imparts a high velocity to the payload and detaches at the periapsis. This high velocity is characteristic of the Geosynchronous Transfer Orbit. Once the spacecraft reaches the apoapsis of this high eccentricity orbit, it performs a burn using its on-board engine to circularise its orbit.
The high thrust hypergolic liquid propellant Vikas engine's newer improved version with a higher chamber pressure is used here. It is activated 156 seconds into flight.
The first stage of GSLV is ignited 4 seconds after the ignition of the four strap-ons after ensuring their full functionality. This is required in order to extract maximum thrust out of the initial stages. The solid core of the first stage burns for 100 seconds while the strap-ons continue to provide thrust for another 56 seconds.
The GSLV uses 4 liquid strap-on motors. The strap-ons are powered by one Vikas engine each and along with the solid rocket motor core of the first stage, provide an enormous thrust to the launcher.


Payload to GTO: 2,500 kg

GSLV's primary payloads are INSAT class of communication satellites that operate from Geostationary orbits and hence are placed in Geosynchronous Transfer Orbits by GSLV.

Payload to LEO: 5,000 kg

Further, GSLV's capability of placing up to 5 tonnes in Low Earth Orbits broadens the scope of payloads from heavy satellites to multiple smaller satellites.

Third Stage: CUS

Developed under the Cryogenic Upper Stage Project (CUSP), the CE-7.5 is India's first cryogenic engine, developed by the Liquid Propulsion Systems Centre. CE-7.5 has a staged combustion operating cycle.

Fuel: LOX + LH2
Max. Thrust: 75 kN
Burn-time: 720 sec

Second Stage: GS2

One Vikas engine is used in the second stage of GSLV. The stage was derived from the PS2 of PSLV where the Vikas engine has proved its reliability.

Engine: Vikas
Fuel: UDMH + N2O4
Max. Thrust: 800 kN
Burntime: 150 sec

First Stage: GS1

The first stage of GSLV was also derived from the PSLV's PS1. The 138 tonne solid rocket motor is augmented by 4 liquid strap-ons.

Engine: S139
Fuel: HTPB
Max. Thrust: 4700 kN
Burntime: 100 sec

Strap-on Motors

The four liquid engine strap-ons used in GSLV are heavier derivatives of PSLV's PS2, and use one Vikas engine each.

Fuel: UDMH + N2O4
Max. Thrust: 680 kN
Burntime: 160 sec