GSLV Mark III
The Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk III), also referred to as the Launch Vehicle Mark 3 (LVM3), is a three-stage medium-lift launch vehicle developed by the Indian Space Research Organisation (ISRO). Primarily designed to launch communication satellites into geostationary orbit, it is also identified as the launch vehicle for crewed missions under the Indian Human Spaceflight Programme and dedicated science missions like Chandrayaan-2. The GSLV Mk III has a higher payload capacity than the similarly named GSLV Mk II. After several delays and a sub-orbital test flight on 18 December 2014 , ISRO successfully conducted the first orbital test launch of GSLV Mk III on 5 June 2017 from the Satish Dhawan Space Centre, Andhra Pradesh. In June 2018, the Union Cabinet approved to build 10 GSLV Mk III rockets over a five-year period. The GSLV Mk III launched CARE, India's space capsule recovery experiment module, Chandrayaan-2, India's second lunar mission, and will be used to carry Gaganyaan, the first crewed mission under Indian Human Spaceflight Programme. In October 2021, UK-based global communication satellite provider OneWeb entered into an agreement with ISRO to launch OneWeb satellites aboard the  GSLV Mk III along with the PSLV. History. Development. ISRO initially planned two launcher families, the Polar Satellite Launch Vehicle for low Earth orbit and polar launches and the larger Geosynchronous Satellite Launch Vehicle for payloads to geostationary transfer orbit (GTO). The vehicle was reconceptualized as a more powerful launcher as the ISRO mandate changed. This increase in size allowed the launch of heavier communication and multipurpose satellites, future interplanetary exploration and will be human rated to launch crewed missions. Development of the GSLV Mk III began in the early 2000s, with the first launch planned for 2009–2010. The unsuccessful  launch of GSLV D3, due to a failure in the cryogenic upper stage, delayed the GSLV Mk III development program. The GSLV Mk III, while sharing a name with the GSLV, features different systems and components. S200 static fire tests. The first static fire test of the S-200 solid rocket booster, ST-01, was conducted on 24 January 2010. The booster fired for 130 seconds and had nominal performance. It generated a peak thrust of about . A second static fire test, ST-02, was conducted on 4 September 2011. The booster fired for 140 seconds and had nominal performance. A third test , ST-03, was conducted on 14 June 2015 to validate the changes from the sub-orbital test flight data. L110 static fire tests. ISRO conducted the first static test of the L110 core stage at its Liquid Propulsion Systems Centre (LPSC) test facility at Mahendragiri, Tamil Nadu on 5 March 2010. The test was planned to last 200 seconds, but was terminated at 150 seconds after a leakage in a control system was detected. A second static fire test for the full duration was conducted on 8 September 2010. C25 stage tests. The first static fire test of the C25 cryogenic  stage was conducted on 25 January 2017 at the ISRO Propulsion Complex (IPRC) facility at Mahendragiri, Tamil Nadu. The stage was tested for a duration of 50 seconds and had nominal performance. A second static fire test for the full in-flight duration of 640 seconds was completed on 17 February 2017. This test demonstrated the repeatability of the engine performance along with its sub-systems, including the thrust chamber, gas generator, turbopumps and control components for the full duration. All of the engine parameters had nominal performance. Modifications after LVM3-X. After the suborbital test flight of GSLV Mk  III, certain modifications were made to the vehicle to improve its performance. The propellant grain geometry of head end segment was changed to a 13-lobed star configuration from a 10-lobed slotted configuration and propellant load was reduced to to improve performance during transonic phase of launch. The CFRP payload fairing was modified to ogive shape, and the S200 booster nosecones were slanted to improve aerodynamic performance. The open inter-tank structure of the C25 cryogenic stage was redesigned to be enclosed for better aerodynamic performance. Vehicle design. The first stage consists of two S200 solid motors, also known  as Large Solid Boosters (LSB) attached to the core stage. Each booster is wide, long, and carries of hydroxyl-terminated polybutadiene (HTPB) based propellant in three segments with casings made out of M250 maraging steel. It is the largest solid-fuel booster after the Space Shuttle SRBs and Ariane 5 SRBs. The flex nozzles can be vectored up to ±8° using electro-hydraulic actuators operating in blow-down mode and are used for vehicle control during the initial ascent phase. Hydraulic fluid for operating these actuators is stored in an externally mounted cylindrical tank at the base of each  booster. These boosters burn for 130 seconds and produce an average thrust of and a peak thrust of each. The second stage, designated L110, is a liquid-fueled stage that is tall and wide, and contains of unsymmetrical dimethylhydrazine (UDMH) and nitrogen tetroxide (). It is powered by two Vikas 2 engines, each generating thrust, giving a total thrust of . The L110 is the first Indian clustered liquid-fueled engine. The Vikas engines uses regenerative cooling, providing improved weight and specific impulse compared to earlier Indian rockets. Each Vikas engine can be individually gimbaled to control vehicle pitch, yaw and roll  control. The L110 core stage ignites 114 seconds after liftoff and burns for 203 seconds. Since the L110 stage is air-lit, its engines need shielding during flight from the exhaust of the operating S200 boosters and reverse flow of gases by a 'nozzle closure system' which gets jettisoned prior to L110 ignition. The cryogenic upper stage, designated C25, is in diameter and long, and contains of propellant LOX and LH2, pressurized by helium stored in submerged bottles. It is powered by a single CE-20 engine, producing of thrust. CE-20 is the first cryogenic engine developed by India which uses  a gas generator, as compared to the staged combustion engines used in GSLV. The CFRP composite payload fairing has a diameter of and a payload volume of . Variants and upgrades. Mating with semi-cryogenic stage. The L110 core stage in the GSLV Mk III is planned to be replaced by a kerolox stage powered by the SCE-200 engine to increase its payload capacity to to geostationary transfer orbit (GTO). The SCE-200 uses kerosene instead of unsymmetrical dimethylhydrazine (UDMH) as fuel and can exert a thrust of around 200 tonnes. Four such engines can be clustered in a rocket without strap  on boosters to deliver up to to GTO. The hydrolox upper stage C25 with nearly propellant load will be converted into C32 with higher propellant load of . Total mass of avionics will be brought down by the use of miniature versions. On 30 November 2020, Hindustan Aeronautics Limited (HAL) delivered an aluminium alloy based cryogenic tank, namely C32-LH2 to ISRO. The tank has capacity to accommodate of fuel in a volume of , designed to increase payload capacity of GSLV Mk III. The SCE-200 powered version will not be used for the crewed mission of the "Gaganyaan" spacecraft. In September  2019, a report quoted S. Somanath, director of Vikram Sarabhai Space Centre (VSSC) said that the semi-cryogenic engine was ready to begin testing. The SCE-200 is reported to be based on the Ukrainian RD-810. As per a frame agreement for cooperation in the peaceful uses of outer space between India and Ukraine signed in 2005, Ukraine was expected to test components of the Indian version of the engine and will fly only after successful completion of the "Gaganyaan" program. So, an upgraded version of the GSLV Mk III was not expected arrive before 2022. The propellant tank for the  SC120 semi-cryogenic stage was delivered in October 2021 by HAL. Human-rating. While the GSLV Mk III is being human rated for Gaganyaan project, the rocket was designed with potential human spaceflight applications in consideration. The maximum acceleration during ascent phase of flight was limited to 4 g for crew comfort and 5 meter diameter payload fairing was inducted to be able to accommodate large modules like space station segments. Furthermore, a number of changes to make safety critical subsystems reliable are planned through lower operating margins, redundancy, stringent qualification requirements, revaluation, and strengthening of components. In Avionics: Vehicle  stages: Notable missions. X (Suborbital flight test). The maiden flight of the GSLV Mk III occurred on 18 December 2014. The flight lifted off from the Second Launch Pad, at 04:00 UTC. The test had functional boosters, a core stage and a non-functional dummy upper stage. It carried the Crew Module Atmospheric Re-entry Experiment (CARE) that was tested on re-entry. Just over five minutes into the flight, the rocket ejected CARE module at an altitude of , which then descended, controlled by its onboard motors. During the test CARE's heat shield experienced a maximum temperature of around  . ISRO downloaded launch telemetry during the ballistic coasting phase before the radio black-out to avoid data loss in the event of a splash-down failure. At an altitude of around , the module's apex cover separated and the parachutes were deployed. CARE splashed down in the Bay of Bengal near the Andaman and Nicobar Islands and was recovered successfully. D1 (GSAT-19). The first orbital flight of the GSLV Mk III occurred on 5 June 2017, lifting off from the Second Launch Pad at 11:58 UTC. The vehicle carried the GSAT-19 communication satellite, making it the heaviest Indian rocket and  payload ever launched. The satellite was successfully placed into a geostationary transfer orbit (GTO) at . The flight also tested upgrades to the design from data acquired during the suborbital test flight (See section on redesigns). M1 (Chandrayaan-2). The first operational flight occurred on 22 July 2019, lifting off from the Second Launch pad at 9:13 UTC. The rocket carried Chandrayaan-2, India's second mission to the Moon, consisting of an orbiter, lander and a rover. The Chandrayaan-2 stack is the heaviest spacecraft launched by ISRO.