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Geosynchronous Satellite Launch Vehicle (GSLV), Stages, Missions and Significance

The Geosynchronous Satellite Launch Vehicle (GSLV) is a space launch vehicle developed and operated by the Indian Space Research Organization (ISRO) for launching satellites and other objects into Geosynchronous Transfer Orbits. GSLV is capable of carrying heavier payloads into orbit compared to the Polar Satellite Launch Vehicle (PSLV).

ISRO’s GSLV rocket, nicknamed ‘naughty boy’, due to its mixed record of successes and failures, and its role in advancing India’s space capabilities with the latest satellite launch INSAT-3DS.

Geosynchronous Satellite Launch Vehicle (GSLV)

The Geosynchronous Satellite Launch Vehicle (GSLV) is designed for deploying 2.3-ton class satellites, including communication satellites like INSAT and GSAT, as well as spacecraft from the INRSS and IDRSS series, into Geosynchronous Transfer Orbit (GTO). GSLV is the tallest among ISRO’s launch vehicles, standing at 51.7 meters, with a lift-off mass of 420 tons.

Its first stage combines a powerful S139 solid booster with 138 tons of propellant and four liquid strap-on L40 motors, each with 40 tons of propellant. The second stage, GS2-GL40, uses a liquid engine with 40 tons of liquid propellant, while the indigenous Cryogenic Upper Stage (CUS) carries 15 tons of cryogenic propellants, including Liquid Hydrogen (LH2) and Liquid Oxygen (LOX).

About GSLV Rockets

  • Launch Vehicle Category: GSLV is an expendable launch vehicle designed to deliver satellites into geostationary transfer orbits and as a launcher for intermediate circular orbits.
  • Development: It is part of ISRO’s efforts to achieve self-reliance in launching heavier communication satellites.
  • Capabilities: The GSLV has capabilities to carry heavier payloads compared to the PSLV (Polar Satellite Launch Vehicle), including larger satellites into geostationary transfer orbit (GTO).
  • Cryogenic Upper Stage: One of the distinguishing features of the GSLV is its cryogenic upper stage, which uses liquid hydrogen as fuel and liquid oxygen as an oxidizer. Cryogenic engines are technologically complex due to the extremely low temperatures required to maintain the propellants in liquid form.
  • Flight History:The GSLV has had a mixed track record with several successful launches and some failures, attributed to various technical complexities, particularly related to its cryogenic stage.
  • Significance: GSLV missions are crucial for India’s communication satellite deployment, enhancing the country’s infrastructure in telecommunications, broadcasting, broadband, and satellite-based navigation.

Geosynchronous Satellite Launch Vehicle (GSLV) Stages

The Geosynchronous Satellite Launch Vehicle (GSLV) is a three-stage launch vehicle developed and operated by the Indian Space Research Organization (ISRO). Each stage of the GSLV plays a crucial role in getting payloads into various orbits. Here are the stages of the GSLV:

First Stage (GS1)

  • The first stage is the most powerful and uses a solid rocket motor known as the S139.
  • It also incorporates four liquid engine strap-on boosters.
  • The S139 solid rocket motor provides a significant amount of thrust, which is essential for lifting the rocket off the ground.
  • Maximum Thrust: Approximately 4700 kilo Newton.

Second Stage (GS2)

  • The second stage is a liquid rocket stage and is equipped with a liquid engine called the Vikas engine.
  • The Vikas engine runs on UH25 (unsymmetrical dimethylhydrazine) as fuel and N2O4 (nitrogen tetroxide) as the oxidizer.
  • Maximum Thrust: Approximately 800 kilo Newton.

Third Stage (Cryogenic Upper Stage – CUS)

  • The third stage is the Cryogenic Upper Stage (CUS).
  • It uses a cryogenic engine that relies on liquefied oxygen (LOX) as the oxidizer and liquid hydrogen (LH2) as the fuel.
  • The use of cryogenic fuels in the CUS allows the GSLV to achieve higher performance and carry heavier payloads to geosynchronous orbits.
  • Maximum Thrust: Approximately 75 kilo Newton (for the CE-7.5 cryogenic engine).

These stages work together to propel the GSLV and its payload into various orbits, including Geosynchronous Transfer Orbit (GTO) for communication satellites. The GSLV is known for its capability to launch satellites into geosynchronous orbits, and the development of indigenous cryogenic engines has enhanced its capabilities, reducing the need to rely on foreign technology.

GSLV Launch Date

Up to May 2023, the GSLV family has conducted a total of 15 launches, with 9 successful missions, 4 failures, and 2 partial failures. All these launches took place at the Satish Dhawan Space Centre, formerly known as the Sriharikota Range (SHAR).

Year Flight No. Date & Time (UTC) Rocket Configuration Payload Orbit Launch Outcome
2001-2009 D1 18 April 2001 Mk I First GSAT-1 GTO (Geostationary Transfer Orbit) Partial Failure
2001-2009 D2 8 May 2003 Mk I First GSAT-2 GTO Success
2001-2009 F01 20 September 2004 Mk I First GSAT-3 GTO Success
2001-2009 F02 10 July 2006 Mk I Second INSAT-4C GTO Failure
2001-2009 F04 2 September 2007 Mk I Second INSAT-4CR GTO Partial Failure
2010-2017 D3 15 April 2010 Mk II Second GSAT-4 GTO Failure
2010-2017 F06 25 December 2010 Mk I Second GSAT-5P GTO Failure
2010-2017 D5 5 January 2014 Mk II Second GSAT-14 GTO Success
2010-2017 D6 27 August 2015 Mk II Second GSAT-6 GTO Success
2010-2017 F05 8 September 2016 MK II Second INSAT-3DR GTO Success
2010-2017 F09 5 May 2017 Mk II Second GSAT-9 / South Asia Satellite GTO Success
2018 F08 29 March 2018 Mk II Second GSAT-6A GTO Success
2018 F11 19 December 2018 Mk II Second GSAT-7A GTO Success
2021 F10 12 August 2021 Mk II Second GISAT-1 / EOS-03 GTO Failure
2023 F12 29 May 2023 Mk II Second NVS-01 GTO Success

GSLV Future Launch

Date Rocket Configuration Launch Site Payload Orbit User
November 1, 2023 Mk II Second Launch Pad INSAT-3DS GTO ISRO
2024 Mk II Second Launch Pad IDRSS-1 / CMS-4 GTO ISRO
2024 Mk II Second Launch Pad IDRSS-2 GTO ISRO
March 2024 Mk II Second Launch Pad GISAT-2 / EOS-05 GTO ISRO
October 2024 Mk II Second Launch Pad NISAR SSO(Sun-synchronous orbit) NASA / ISRO
December 2024 Mk II Second Launch Pad Venus Orbiter Mission Venus ISRO
TBA GEV Second Launch Pad RLV-ORV LEO (Lower Earth Orbit) ISRO

Milestone GSLV Missions

Mission Description
GSLV MK. I Flight D1 First developmental flight of GSLV Mk.I featuring a Russian cryogenic engine. Launched GSAT-1 but didn’t reach the intended orbit, requiring satellite maneuvering to correct. ISRO claimed it as a success, but later attributed the failure to an incorrect mixture ratio in the cryogenic upper stage.
GSLV MK. II Flight D5 The second test flight with an indigenous cryogenic stage CE-7.5. The first successful launch with CE-7.5. Carried GSAT-14 into orbit, marking a significant milestone in GSLV’s use of indigenous cryogenic technology.
GSLV MK. II Flight F09 The fourth consecutive successful flight of GSLV Mk. II with an indigenous cryogenic engine. Launched the South Asia Satellite, a regional satellite gifted by India to its neighboring countries, supporting Prime Minister Narendra Modi’s neighborhood-first policy. Afghanistan, Bangladesh, Bhutan, Maldives, Nepal, and Sri Lanka are the users of the satellite.

What is the GSLV MKIII?

The GSLV MkIII, approved in 2002, is a crucial step for India’s space program, designed to launch 4-ton class satellites into Geo-Synchronous orbit. With a height of 43.5 meters and a gross lift-off weight of 640 tonnes, it employs three stages, including two solid strap-on motors, a liquid core stage, and an indigenous high-thrust cryogenic engine (CE20). Notable features include a 4.3-ton payload capacity to GTO, cost-effectiveness, improved reliability, and support for future manned missions like the successful 2019 launch of the Chandrayaan-2 spacecraft into Super Geo-Synchronous Transfer Orbit.


Characteristic GSLV PSLV
Full Form Geosynchronous Satellite Launch Vehicle Polar Satellite Launch Vehicle
Developed and Operated by Indian Space Research Organization (ISRO) Indian Space Research Organization (ISRO)
Primary Purpose Deploy satellites into Geosynchronous Transfer Orbit (GTO) Deploy satellites into polar orbits
Payload Capacity Can carry heavier payloads into GTO Suited for lighter payloads into polar orbits
Stages Three-stage launch vehicle Four-stage launch vehicle
First Stage S139 solid rocket motor with liquid strap-on boosters PS1: Solid Rocket Motor
Second Stage Liquid stage with the Vikas engine PS2: Liquid Stage
Third Stage Cryogenic Upper Stage (CUS) PS3: Solid Rocket Motor (Optional)
Number of Launches (as of May 2023) 15 launches (9 successful, 4 failures, 2 partial failures) Over 50 launches with a high success rate
Notable Missions Includes GSLV MK. I Flight D1, MK. II Flight D5, MK. II Flight F09, and others Known for successful launches of numerous satellites
Cryogenic Engine Features a cryogenic engine in the third stage Does not incorporate a cryogenic engine
Versatility Suited for deploying communication satellites into GTO Ideal for deploying Earth observation and remote sensing satellites
Commercial Launches Competes in the global commercial launch market Offers commercial launch services for international clients
Recent Achievements Launched satellites into GTO and expanded ISRO’s capabilities Contributed to India’s space achievements and international collaboration
Reliance on Foreign Technology Reduced reliance through the development of indigenous cryogenic technology Limited reliance on foreign technology


Geosynchronous Satellite Launch Vehicle (GSLV) Significance 

  • Payload Capacity: GSLV can carry heavier payloads into Geosynchronous Transfer Orbit (GTO), making it ideal for launching communication satellites.
  • Geosynchronous Orbit Access: It deploys satellites into Geosynchronous Orbit (GEO), crucial for telecommunications and broadcasting services.
  • Cryogenic Engine Development: GSLV contributed to India’s indigenous cryogenic engine technology, reducing reliance on foreign engines.
  • Commercial Launch Services: GSLV is competitive in the global commercial launch market, carrying payloads for international clients.
  • National Security: It supports strategic and defense purposes by deploying surveillance and communication satellites.
  • International Collaboration: GSLV missions promote global collaboration and trust in India’s space capabilities.
  • Technological Advancement: It advances India’s space technology, enhancing self-reliance.
  • Diverse Space Services: GSLV facilitates a range of space-based services, including communication, navigation, and Earth observation.


The Geosynchronous Satellite Launch Vehicle (GSLV) is a pivotal component of India’s space program, designed for deploying 2.3-ton class satellites into Geosynchronous Transfer Orbit (GTO), including communication and navigation satellites. GSLV is renowned for its indigenous cryogenic engine, reducing reliance on foreign technology. It has successfully contributed to both domestic and international space endeavors, offering commercial launch services and enhancing India’s self-reliance in space technology. Furthermore, GSLV plays a vital role in national security, deploying surveillance and communication satellites. Overall, GSLV stands as a symbol of India’s space achievements, promoting global collaboration and enabling diverse space-based services.

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Geosynchronous Satellite Launch Vehicle (GSLV) FAQs

What is GSLV?

GSLV stands for Geosynchronous Satellite Launch Vehicle, a space launch vehicle developed and operated by the Indian Space Research Organization (ISRO) for deploying satellites into Geosynchronous Transfer Orbits (GTO).

How does GSLV differ from PSLV?

GSLV can carry heavier payloads into GTO, while the Polar Satellite Launch Vehicle (PSLV) is designed for launching satellites into polar orbits.

What is the main purpose of GSLV?

GSLV is primarily designed for deploying 2.3-ton class satellites into GTO, including communication and navigation satellites.

How many stages are there in GSLV?

GSLV is a three-stage launch vehicle consisting of the first stage, second stage, and the Cryogenic Upper Stage (CUS).

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