The Indian space agency, ISRO (Indian Space Research Organisation), has been developing an environment-friendly propellant to power Indian satellites and spacecrafts. This ‘green fuel’ is meant to replace the usual hydrazine fuel mixture, which is known to be toxic and the carcinogenic chemicals. Scientists from ISRO’s Liquid Propulsion Systems Center (LPSC) have been experimenting with a new propellant blend that’s based on hydroxylammonium nitrate (HAN). Their initial tests have reportedly yielded promising results.
LPSC team members tested for various characteristics, like thermal and catalytic decomposition, and the compatibility of HAN with different materials. This led them to discover the HAN-based monopropellant, which is a propulsion fuel that doesn’t need a separate oxidizer. The reason hydrazine is usually preferred for fuel is because of its high performance. It’s akin to energy dependence on coal, where harmful energy is useful despite its hazardous effect on the environment and health. Also, there are challenges that come with having to manufacture, store, transport and actually use hydrazine.
The concoction includes HAN, ammonium nitrate (AN), methanol and water. The methanol helps reduce combustion instability, while AN has the capacity to regulate the burn rate and further reduce the freezing point of the propellant. On other fronts, the LPSC is currently working on the 800 Newton liquid main engine propellant for the country’s Chandrayaan-2 Moon mission that is set to launch later this year, in October. ISRO has also, slowly and steadily, been working on its reusable launcher. The Reusable Launch Vehicle Technology Demonstrator (RLV-TD) has already demonstrated its capabilities once in 2016, and there’s a second test scheduled for 2019.