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ISRO; Science and technology
News:
- Indian Space Research Organisation (ISRO) seeks to replace hydrazine fuel with an environmental-friendly propellant to power satellites and spacecrafts
Important Facts:
- ISRO is working to replace hydrazine with hydroxylammonium nitrate based (HAN) monopropellant
- Monopropellant is a chemical propulsion fuel which does not require separate oxidizer. It is used in satellite thrusters for orbital correction and orientation control
- Advantages of using Hydrazine
- High performance characteristics: one of the highest specific impulses (kilogram of thrust obtained by consumption of 1 kg of propellant in 1 sec). Therefore, despite hazards, has been preferred as propellant.
Disadvantages of using Hydrazine:
- Highly corrosive
- Carcinogenic and Toxic
- Storage and handling issues
- The HAN-based monopropellant has been formulated by researchers at Liquid Propulsion Systems Centre (LPSC)
- The formulation consists of HAN, ammonium nitrate, methanol and water
- Advantages Of HAN-based Propellants over Hydrazine Propellants:
- Less toxic than hydrazine
- Performance: Higher density (1.4 to 1.5 g/cm3) than hydrazine propellants (1.0g/cm3)
- Safety: Non-combustible, hence, a safer alternative



