Scientists at ISRO’s Liquid Propulsion Systems Centre (LPSC) are developing environment-friendly propellant propellant blend based on hydroxylammonium nitrate (HAN) to power satellites and spacecraft. It seeks to replace conventional hydrazine fuel for future missions.
HAN-based monopropellant formulation consists of HAN, ammonium nitrate, methanol and water. The methanol was added to reduce combustion instability and HAN was used for its capacity to control burn rate and lower freezing point of propellant.
Monopropellant is chemical propulsion fuel which does not require separate oxidizer. It is used extensively in satellite thrusters for orbital correction and orientation control.
The propellant formulation was tested for compatibility with four metal samples over period of six months. Moreover, variety of tests to investigate its characteristics, like thermal and catalytic decomposition and compatibility was undertaken with different materials.
HAN-based monopropellant will replace conventional hydrazine rocket fuel, a highly toxic and carcinogenic chemical, with greener propellant for future missions. It will also ensure cost effective re-usable, recoverable, re-startable and reliable space launches of ISRO. Due to its high performance characteristics, hydrazine has dominated space industry as choice of propellant for over six decades despite hazards.