What is the issue ?
- Scientists at ISRO have reported making progress in the development of environment friendly propellant.
What about the propellant which is in use now ?
- Hydrazine is the propellant in use at the moment.
- Hydrazine has one of the highest specific impulses (kilograms of thrust obtained by consumption of one kilogram of propellant in one second).
- Hydrazine is still in use because of its high performance inspite of having several drawbacks.
Drawbacks of using hydrazine :
- Carcinogenic and toxic
- Highly corrosive
- Storage and handling of hydrazine is difficult.
So what is the alternative that ISRO is looking at ?
- ISRO is working on a hydroxylammonium nitrate (HAN) based monopropellant.
- The inhouse formulation consists of HAN, ammonium nitrate, methanol and water. While methanol was added to reduce combustion instability, the choice of AN was dictated by its capacity to control the burn rate and lower the freezing point of the propellant.
Advantages of switching over to HAN :
- Less toxic when compared to hydrazine
- Not easily prone to combustion
What are monopropellants ?
- A monopropellant is a chemical propulsion fuel which does not require a separate oxidizer. It is used extensively in satellite thrusters for orbital correction and orientation control.