Green propellants and ISRO
ISRO is developing green propellants for use in future rocket & satellite propulsion systems. All space faring nations have been investigating green propulsion systems to minimise environmental impact while improving overall efficiency and economy.
ISRO has made a beginning by developing an eco-friendly solid propellant based on Glycidyl Azide Polymer (GAP) as fuel and Ammonium Di-Nitramide (ADN) as oxidizer at the laboratory level, which will eliminate the emission of chlorinated exhaust products from rocket motors.
In addition, ISRO is also carrying out various technology demonstration projects involving green propellant combinations such as Hydrogen Peroxide (H2O2), Kerosene, Liquid Oxygen (LOX), Liquid Methane, ADN-Methanol-water, ADN-Glycerol-water etc.
ISRO has already begun the move towards environment-friendly and green propellants with the acceptance of Liquid Oxygen (LOX)/Liquid Hydrogen (LH2) and LOX/Kerosene based propulsion systems for launch vehicles, and use of electric propulsion for spacecraft. The LOX/LH2 combination is already being used in the cryogenic upper stages of GSLV and GSLV Mk-III launch vehicles.
ISRO has successfully developed ISROSENE, which is a rocket grade version of kerosene as an alternative to conventional hydrazine rocket fuel. ISRO has successfully demonstrated electric propulsion system for station keeping operations in the South Asia Satellite, launched on May 5, 2017.