GSLV – Space Launch Report

GSLV - Space Launch Report

India’s Space Research Organization’s (ISRO) 401 metric ton, 49 meter-tall, three-stage Geosynchronous Satellite Launch Vehicle (GSLV), designed to loft 2 ton satellites to geosynchronous transfer orbit (GTO), is a conglomerate of Indian, European, and Russian components. ISRO developed the rocket during the 1990s to create an indigenous communication satellite launch capability for India.


ISRO adapted stages from India’a Polar Satellite Launch Vehicle (PSLV) for GSLV. The first stage solid propellant motor and the liquid propellant second stage of PSLV, itself powered by engines used by Europe’s Ariane 1, serve as the core first stage motor and the second stage of GSLV. The PSLV second stage was also used as the basis for the GSLV first stage liquid strap-on stages.

The first stage uses a 20.3 x 2.8 meter (m), 480 ton thrust solid motor, augmented by four 19.7 x 2.1 m L40 liquid strap-on motors. The non-separating L40s are powered by 70 ton thrust Viking 2 engines that burn UDMH/N2O4 for 160 seconds, 60 seconds longer than the core.

GSLV’s 11.6 x 2.8 m GS-2 second stage starts its Viking 4 70 ton thrust engine just before first stage cutoff, to ensure propellant settling, and burns for 160 seconds. The Glavkosmos 12KRB Cryogenic Stage (CS) then ignites its 73.5 kN KVD-1 LH2/LOX engine for a planned 710 second burn. CS is the first Russian-built liquid-hydrogen upper stage to fly, but ISRO plans to replace it with its own LH2 third stage in a few years.

The vehicle is controlled by a strap-down inertial navigation/guidance system housed in a vehicle equipment bay that is mounted on a truss structure atop the third stage. A 7.8 meter tall, 3.4 meter diameter payload fairing protects the payload during ascent until it is jettisonned at an altitude of about 110 km during the second stage burn.

ISRO launched its first GSLV from Satish Dhawan Space Centre, SHAR, Sriharikota on April 18, 2001. An early third stage cutoff denied the 49-meter tall rocket’s total success in the inaugural D-1 mission. G-Sat 1, a 1,540 kg test payload, fell about 4,000 km short of its planned 36,000 km geosynchronous transfer orbit (GTO) apogee. G-Sat was unable to make up the difference with its apogee motor and it ended up stranded in a 23-hour drift orbit. GSLV flew successfully in 2003 and 2004.

During a typical flight, the four liquid propellant (L-40) strap-on stages are ignited first. The solid propellant core stage, S125, is ignited 4.6 seconds later and liftoff occurs. The core stage burns for 100 seconds and the four L-40 strap-on stages continue to burn for an additional 60 seconds. Staging occurs at an altitude of about 73 km.

The GS2 liquid propellant second stage ignites 1.6 seconds before the separation of first stage, using a “fire in the hole” start sequence. The second stage burns for about 150 seconds. The payload fairing separates at about the 260 second point. Second stage separation occurs about 314 seconds after lift-off at an altitude of about 127 km.

The cryogenic third performs a single 710 second burn, boosting the payload to a velocity of 10.2 km per second. at an altitude of 195 km. This injects the payload into an elliptical transfer orbit (GTO) with a perigee of 180 km and an apogee of 35,975 km.

The original PSLV/GSLV launch complex was replaced in 2005 with a new, mobile launch facility. Whereas the original pad featured fixed launch stand and a 75 meter tall mobile service tower, the new pad uses rail-mobile launch stands that allow vehicles to be stacked in a vertical integration building located some distance from the launch pad itself.


GSLV - Space Launch Report

GSLV serial F-02, the fourth GSLV to fly, failed during its July 10, 2006 attempt to launch Insat 4C from Satish Dhawan Space Center on Sriharikota island on India’s east coast.

The failure began to make itself apparent almost immediately after liftoff when one of four liquid-fueled strap-on boosters failed. This created asymmetrical thrust that caused the vehicle to veer from its planned flight path.   The 49-metre-tall, 414 tonne, three-stage launcher broke up at relatively low altitude and fell into the Bay of Bengal within sight of the launch pad.

On July 31, 2006 ISRO Chairman G Madhavan Nair said that preliminary results of the investigation pointed toward a malfunction of the thrust controller in the strap-on booster engine.  Each booster is powered by a single 70-tonne thrust Vikas engine fed by 42 tonnes of hypergolic liquid propellant. Vikas are derived from Viking 2 engines originally used by Europe’s Ariane 1 launcher. 

Also read: Cape Canaveral Space Artifacts

Vehicle Configurations

(metric tons)
200 km x 45 deg
(metric tons)
GSLV5 t2 t3 stage GSLV with
Russian 3rd Stage Engine
49 m401 t

Vehicle Components

 Stage 1 Core
Stage 1 (GS1)
L40 Strap-On
(Each of 4)
(Not Jettisoned)
Stage 2
Stage 3
Diameter (m)2.8 m2.1 m2.8 m2.8 m2.8 m
Length (m)20.3 m19.7 m11.6 m8.7 m7.8 m
Propellant Mass (tons)129 t40 t37.5 t12.5 t 
Total Mass (tons)156 t46 t42.8 t15 t 
EngineS125Viking 2Viking 412KRB 
Engine Mfgr SEPSEPGlavkosmos 
Oxidizer N2O4N2O4LOX 
(SL tons)
(Vac tons)
479.3 t69.34 t73.41 t7.65 t 
ISP (SL sec)237 s240 s   
ISP (Vac sec)266 s281 s295 s460 s 
Burn Time (sec)100 s160 s150 s750 s 
No. Engines14111
T-4.6 sL40 Strap-on Boosters Ignite0 km0
T+0 sS125 Core Stage Ignites – Liftoff0 km0
T+100 sS125 Core Stage Burn Outkm 
T+158.4 sL40 Second Stage Igniteskm 
T+160 sL40 First Stage Booster Burn Out/Stage Separation73 km 
T+260 sPayload Fairing Separation110 km 
T+310 sSecond Stage Shut Down120 km 
T+314 sSecond/Third Stage Separation/Third Stage Ignition127 km 
T +1024 sThird Stage Shut Down195 km10.2 km/s

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