GSLV Full Form

GSLV full form, Geosynchronous Satellite Launch Vehicle, is an expendable launch vehicle operated by the Indian Space Research organization. It was used from 2001 to 2018 in thirteen launches, with more launches planned.  It is an entirely different launch vehicle. The GSLV project was started in 1990 to acquire an Indian launch capability of a geosynchronous satellite (a satellite in geosynchronous orbit with an orbital period similar to the Earth’s rotational period). 

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GSLV History

GSLV abbreviation, Geosynchronous Satellite Launch Vehicle, project was started in 1990 to acquire the Indian Government launch ability of Geosynchronous satellites.

The major components used by the GSLV were already proven in the Polar Satellite Launch Vehicle launchers in the form of the S125/S135 solid rocket booster and the liquid fuel booster engine. 

The first development flight of the GSLV (MK Configuration I), launched on April 18, 2001, was a failure as the payload failed to reach the desired orbit parameters. The launcher was declared functional after the second development flight successfully launched the GSAT-2 satellites. During the first few years from the initial launch to 2014, the launcher had a patterned history with only 2 successful launches out of 7.

GSLV Launch History

As of April 20, 2021, the GSLV has made a total of 13 launches. Out of 13 launches made by GSLV, 8 successfully reached their planned orbit, 3 completely failed and two partially failed, yielding a success rate for GSLV MK I at 29% and 86% for MK II variants.  All GSLV launches have occurred from Satish Dhawan Space Centre, known before 2022 as Sriharikota Range.

GSLV Vehicle Description

GSLV is a three-stage expendable launch vehicle with solid, liquid, and cryogenic stages respectively. The vehicle is 49 m ( 161 ft) tall, with a lift mass of 415 t (408 long tons and 457 short tons).

GSLV’s payload safeguards the vehicle electronics and spacecraft during its rising through the atmosphere. It is 7.8 m (26 ft) and 3.4 m (11 ft) in long diameter. It is discarded when the vehicle reaches an altitude of 115 Km (71 mi).

GSLV uses S-band telemetry and C-band transponders for empowering vehicles' performance, tracking, range safety/flight safety, and determining the preliminary orbit. The GSLV vehicle Redundant Strapdown Inertial Navigation System/Inertial Guidance System enclosed in its equipment assists the vehicles from lifting off to spacecraft injection. The digital autopilot and closed-loop support scheme assure the required altitude activities and assists injection of the spacecraft to the specified orbit.

GSLV Stages

Following are three different GSLV stages.

First Stage

GSLV - D1 uses the S125 stage which includes the 125 t of solid propellant and has a burn time of 100 seconds. All subsequent launches have used the S139 stages. The S139 stage is 2.8 in diameter and has a nominal burn time of 100 seconds. 

Second Stage

The GS2 stage is electrically powered by Vikas Engine with a diameter of 2.8 m (9 feet 2 inches).

Third Stage

The third stage of GSLV Mark II is propelled by the Indian CE - 7.5 Cryogenic rocket engine whereas Mark I is launched by using Russian-made KVD - I.  It uses both liquid hydrogen and liquid oxygen. At the ISRO’s Liquid Propulsion System Centre, the Indian cryogenic engine was built. The cryogenic engine has a default thrust of 75 kN (17000 lb) but is capable of a maximum thrust of 93.1 kN (20,900lb).

GSLV Variants

GSLV rockets using the Russian Cryogenic Stage are designated as the GSLV Mark I while versions using the Indigenous Cryogenic Upper Stage  (CUS) are designated GSLV Mark II. All GSLV launches have been conducted from the Satish Dhawan Space Centre in Sriharikota.