 | |
 | |
| Function | Medium-lift Launch System |
|---|---|
| Manufacturer | ISRO |
| Country of origin | India |
| Cost per launch | US$47 million[1] |
| Size | |
| Height | 49.13 m (161.2 ft)[2] |
| Diameter | 2.8 m (9 ft 2 in) |
| Mass | 414,750 kg (914,370 lb) |
| Stages | 3 |
| Capacity | |
| Payload toLEO | |
| Mass | 6,000 kg (13,000 lb)[3] |
| Payload toSSO | |
| Mass | 3,000 kg (6,600 lb)[3] |
| Payload toGTO | |
| Mass | 2,500 kg (5,500 lb)[2][4] |
| Launch history | |
| Status |
|
| Launch sites | Satish Dhawan Space Centre |
| Total launches | 18 + 6 (planned) |
| Success(es) | 12 |
| Failure | 4 |
| Partial failure | 2 |
| First flight |
|
| Last flight |
|
| Carries passengers or cargo | |
| Boosters | |
| No. boosters | 4 L40 Hs |
| Height | 19.7 m (65 ft)[5] |
| Diameter | 2.1 m (6 ft 11 in) |
| Propellant mass | 42,700 kg (94,100 lb) each |
| Powered by | 1L40H Vikas 2 |
| Maximum thrust | 760 kN (170,000 lbf)[6] |
| Total thrust | 3,040 kN (680,000 lbf) |
| Specific impulse | 262 s (2.57 km/s) |
| Burn time | 154 seconds |
| Propellant | N2O4 /UDMH |
| First[6][5] stage | |
| Height | 20.2 m (66 ft) |
| Diameter | 2.8 m (9 ft 2 in) |
| Propellant mass | 138,200 kg (304,700 lb) |
| Powered by | 1S139 Booster |
| Maximum thrust | 4,846.9 kN (1,089,600 lbf) |
| Specific impulse | 237 s (2.32 km/s) |
| Burn time | 100 seconds |
| Propellant | HTPB (solid) |
| Second[6][5] stage | |
| Height | 11.6 m (38 ft) |
| Diameter | 2.8 m (9 ft 2 in) |
| Propellant mass | 39,500 kg (87,100 lb) |
| Powered by | 1GS2 Vikas 4 |
| Maximum thrust | 846.8 kN (190,400 lbf) |
| Specific impulse | 295 s (2.89 km/s) |
| Burn time | 139 seconds |
| Propellant | N2O4 / UDMH |
| Second GS2 (GL40)[6][7] stage | |
| Height | 11.9 m (39 ft) |
| Diameter | 2.8 m (9 ft 2 in) |
| Propellant mass | 42,500 kg (93,700 lb) |
| Powered by | 1GS2 Vikas 4 |
| Maximum thrust | 846.8 kN (190,400 lbf) |
| Specific impulse | 295 s (2.89 km/s) |
| Burn time | 149 seconds |
| Propellant | N2O4 / UDMH |
| Third[5] stage (GSLV Mk I) – CUS | |
| Height | N/A |
| Diameter | 2.8 m (9 ft 2 in) |
| Propellant mass | N/A |
| Powered by | 1KVD-1 |
| Maximum thrust | 70 kN (16,000 lbf) |
| Specific impulse | 462 s (4.53 km/s) |
| Burn time | N/A |
| Propellant | LOX /LH2 |
| Third[5] stage (GSLV Mk II) – CUS12 | |
| Height | 8.7 m (29 ft) |
| Diameter | 2.8 m (9 ft 2 in) |
| Propellant mass | 12,800 kg (28,200 lb) |
| Powered by | 1CE-7.5 |
| Maximum thrust | 75 kN (17,000 lbf) |
| Specific impulse | 454 s (4.45 km/s) |
| Burn time | 718 seconds |
| Propellant | LOX /LH2 |
| Third[7] stage (GSLV Mk II) – CUS15 | |
| Height | 9.9 m (32 ft) |
| Diameter | 2.8 m (9 ft 2 in) |
| Propellant mass | 15,000 kg (33,000 lb) |
| Powered by | 1CE-7.5 |
| Maximum thrust | 75 kN (17,000 lbf) |
| Specific impulse | 454 s (4.45 km/s) |
| Burn time | 846 seconds |
| Propellant | LOX /LH2 |
Geosynchronous Satellite Launch Vehicle (GSLV) is a class ofexpendable launch systems operated byISRO. GSLV has been used ineighteen launches since 2001.
The Geosynchronous Satellite Launch Vehicle (GSLV) project was initiated in 1990 with the objective of acquiring an Indian launch capability forgeosynchronous satellites.[8][9]
GSLV uses major components that are already proven in thePolar Satellite Launch Vehicle (PSLV) launch vehicles in the form of the S125/S139solid rocket booster and theliquid-fueledVikas engine. Due to the thrust required for injecting the satellite in ageostationary transfer orbit (GTO) the third stage was to be powered by aLOX/LH2 Cryogenic engine which at that time India did not possess or have the technological expertise to build. The aerodynamic characterization research was conducted at theNational Aerospace Laboratories' 1.2m Trisonic Wind Tunnel Facility.[10]
The first development flight of the GSLV (Mk I configuration) was launched on 18 April 2001 was a failure as the payload failed to reach the intended orbit parameters. The launcher was declared operational after the second development flight successfully launched theGSAT-2 satellite. During the initial years from the initial launch to 2014 the launcher had a checkered history with only 2 successful launches out of 7, resulting in the rocket gaining the nickname "naughty boy".[11][12]
The third stage was to be procured from Russian companyGlavkosmos, including transfer of technology and design details of the engine based on an agreement signed in 1991.[9] Russia backed out of the deal after United States objected to the deal as in violation of theMissile Technology Control Regime (MTCR) in May 1992. As a result, ISRO initiated theCryogenic Upper Stage Project in April 1994 and began developing its own cryogenic engine.[13] A new agreement was signed with Russia for 7KVD-1 cryogenic stages and 1 ground mock-up stage with no technology transfer, instead of 5 cryogenic stages along with the technology and design as per the earlier agreement.[14] These engines were used for the initial flights and were named GSLV Mk I.[15]
The 49 m (161 ft) tall GSLV, with a lift-off mass of 415 t (408 long tons; 457 short tons), is a three-stage vehicle with solid, liquid and cryogenic stages respectively. The payload fairing, which is 7.8 m (26 ft) long and 3.4 m (11 ft) in diameter, protects the vehicle electronics and the spacecraft during its ascent through the atmosphere. It is discarded when the vehicle reaches an altitude of about 115 km (71 mi).[16][needs update]
GSLV employsS-band telemetry andC-band transponders for enabling vehicle performance monitoring, tracking, range safety / flight safety and preliminary orbit determination. The Redundant Strap Down Inertial Navigation System/Inertial Guidance System of GSLV housed in its equipment bay guides the vehicle from lift-off to spacecraft injection. The digital auto-pilot and closed loop guidance scheme ensure the required altitude maneuver and guide injection of the spacecraft to the specified orbit.
The GSLV can place approximately 5,000 kg (11,000 lb) into an easterlylow Earth orbit (LEO) or 2,500 kg (5,500 lb) (for the Mk II version) into an 18°geostationary transfer orbit.
The first GSLV flight, GSLV-D1 used the L40 stage. Subsequent flights of the GSLV used high pressure engines in the strap-on boosters called the L40H.[17] The GSLV uses four L40Hliquid strap-on boosters derived from the L37.5 second stage, which are loaded with 42.6 tons ofhypergolic propellants (UDMH andN2O4). The propellants are stored in tandem in two independent tanks 2.1 m (6 ft 11 in) diameter. The engine ispump-fed and generates 760 kN (170,000 lbf) of thrust, with a burn time of 150 seconds.
GSLV-D1 used the S125 stage which contained 125 t (123 long tons; 138 short tons) of solid propellant and had a burn time of 100 seconds. All subsequent launches have used enhanced propellant loaded S139 stage.[17] The S139 stage is 2.8 m in diameter and has a nominal burn time of 100 seconds.[18][19]
The GS2 stage is powered by theVikas engine. It has a diameter of 2.8 m (9 ft 2 in).[18]
The third stage of the GSLV Mark II is propelled by the IndianCE-7.5cryogenic rocket engine while the older defunct Mark I is propelled using a Russian madeKVD-1. It uses liquid hydrogen (LH2) and liquid oxygen (LOX)[20] The Indian cryogenic engine was built at theLiquid Propulsion Systems Centre.[21][22] The engine has a default thrust of 75 kN (17,000 lbf) but is capable of a maximum thrust of 93.1 kN (20,900 lbf). In GSLV-F14 mission, a new white coloured C15 stage was introduced which has more environmental-friendly manufacturing processes, better insulation properties and the use of lightweight materials.[23]
GSLV rockets using the Russian Cryogenic Stage (CS) are designated as the GSLV Mark I while versions using the indigenous Cryogenic Upper Stage (CUS) are designated the GSLV Mark II.[24][25] All GSLV launches have been conducted from theSatish Dhawan Space Centre inSriharikota.
The first developmental flight of GSLV Mark I had a 129 tonne (S125) first stage and was capable of launching around 1500 kg intogeostationary transfer orbit. The second developmental flight replaced the S125 stage with S139. It used the same solid motor with 138 tonne propellant loading. The chamber pressure in all liquid engines were enhanced, enabling a higher propellant mass and burn time. These improvements allowed GSLV to carry an additional 300 kg of payload.[26][27] The fourth operational flight of GSLV Mark I, GSLV-F06, had a longer third stage called the C15 with 15 tonne propellant loading and also employed a4 meter diameter payload fairing.[28][29]
This variant uses an Indian cryogenic engine, the CE-7.5, and is capable of launching 2500 kg into geostationary transfer orbit. Previous GSLV vehicles (GSLV Mark I) have used Russian cryogenic engines.[30]
For launches from 2018, a 6% increased thrust version of the Vikas engine was developed. It was demonstrated on 29 March 2018 in theGSAT-6A launch second stage. It will be used for the four Vikas engines on the first stage boosters on future missions.[31]
A 4m diameter Ogive payload fairing was developed and deployed for the first time in theEOS-03 launch on 12 August 2021, although this launch was a failure due to technical anomalies with the Cryogenic Upper Stage. This will allow GSLV vehicles to accommodate larger payloads.[32]
As of October 2024, ISRO has stopped selling GSLV Mk II Rockets. Eight known launches are planned withNVS Missions,IDRSS Missions,NISAR Mission.[33][34]
TheReusable Launch Vehicle Technology Demonstration program, is a prototypespaceplane concept created by ISRO. For the Orbital return Flight experiment, a modified version of the GSLV Mk. II launcher, with the upper Cryogenic Stage replaced with the PS-4 stage from the PSLV is currently in development, as the RLV won't need all the excess energy produced by the CUS .[35][36]
| Variant | Launches | Successes | Failures | Partial failures |
|---|---|---|---|---|
| GSLV Mk. I | 6 | 2 | 2 | 2 |
| GSLV Mk. II | 12 | 10 | 2 | 0 |
| Total as of July 2025[update][37] | 18 | 12 | 4 | 2 |
| Decade | Successful | Partial success | Failure | Total |
|---|---|---|---|---|
| 2000s | 2 | 2 | 1 | 5 |
| 2010s | 6 | 0 | 2 | 8 |
| 2020s | 4 | 0 | 1 | 5 |
| Total | 12 | 2 | 4 | 18 |
Besides the new upper stage, the GSLV Mk.2 launched in April was nearly identical to previous versions of the booster
| Organisations |
|  | |||||
|---|---|---|---|---|---|---|---|
| Programmes | |||||||
| Satellites | |||||||
| Space observatories |
| ||||||
| Lunar and planetary spacecraft | |||||||
| Human spaceflight | |||||||
| Launch vehicles |
| ||||||
| Engines |
| ||||||
| Spaceports | |||||||
| Research facilities | |||||||
| Communications | |||||||
| Legislation and policy | |||||||
| Private companies | |||||||
| Related |
| ||||||
