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  • Indian Space Research Organisation (ISRO) is working on upgrading its heavylifter GSLV Mk III where the upper stage of the rocket will have highly refined form of kerosene as fuel in order to increase its payload capability.


  • To increase the payload capability of GSLV Mk III from 4 tonnes to 6 tonnes, we are in the process of making some improvements in rocket stages.
  • According to ISRO, First, ISRO is working on enhancing the cryogenic stage fuel loading from 25 tonnes to 30 tonnes. Second, ISRO is also working on changing the core stage L110 — which has 110 tonnes of unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide (N2O4)
  • ISRO want to replace L110 stage with semi cryogenic engine that will carry liquefied oxygen and highly refined kerosene called kerolox (aka RP-1) instead of liquefied hydrogen.
  • The rocket with the semicryogenic stage won’t be used for the Gaganyaan mission. The current GSLV Mk III with L110 stage will only be used for the manned mission with some modifications.The advantage of using kerolox is that it is 10 times dense— meaning the same volume of kerolox will generate more thrust than the same volume of hydrolox. It is also cheaper, more stable at room temperature and less hazardous than hydrolox. Elon Musk-promoted Space X currently uses kerolox in its Falcon 9 rocket for launching heavy payloads.
  • With increase in payload capacity, the advanced GSLV MK III will help Isro cut expenses and save time. Currently, India uses the services of Arianespace to launch its heavy satellites weighing over 4 tonnes. Last year on December 4, ISRO had used the services of Arianespace for launching its heaviest satellite Gsat-11 weighing over 5.7 tonnes from French Guiana.


  • GSLV Mk III is a three-stage heavy lift launch vehicle developed by ISRO. The vehicle has two solid strap-ons, a core liquid booster and a cryogenic upper stage. GSLV Mk III is designed to carry 4-ton class of satellites into Geosynchronous Transfer Orbit (GTO) or about 10 tons to Low Earth Orbit (LEO), which is about twice the capability of GSLV Mk II.

Technical Specifications

Payload to GTO: 4,000 kg

  • GSLV Mk III will be capable of placing the 4 tonne class satellites of the GSAT series into Geosynchronous Transfer Orbits.

Payload to LEO: 8,000 kg

  • The powerful cryogenic stage of GSLV Mk III enables it to place heavy payloads into Low Earth Orbits of 600 km altitude.

Cryogenic Upper Stage: C25

  • The C25 is powered by CE-20, India’s largest cryogenic engine, designed and developed by the Liquid Propulsion Systems Centre.

Solid Rocket Boosters: S200

  • SLV Mk III uses two S200 solid rocket boosters to provide the huge amount of thrust required for lift off. The S200 was developed at Vikram Sarabhai Space Centre.

Core Stage: L110 Liquid Stage

  • The L110 liquid stage is powered by two Vikas engines designed and developed at the Liquid Propulsion Systems Centre.
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