Why in News?

• ISRO is planning to develop methane-powered rocket engines.

LOX Methane Engines:

• The space agency is developing two ‘LOx methane’ engines (liquid oxygen oxidiser and methane fuel) engines.
• One of the two projects is trying to convert the existing cryogenic engine, which uses liquid hydrogen for fuel, into a LOx methane engine.
• The other is a smaller engine of 3 tonnes thrust, which will feature an electric motor.
• These are being developed at ISRO’s Liquid Propulsion Systems Centre at Trivandrum.
• ISRO currently prefers to use a fuel called Unsymmetrical Di-Methyl Hydrazine, along with Nitrogen tetroxide for oxidizer, in its liquid fuel (Vikas) engines, which are used in the lower stages of its rockets, PSLV and GSLV.

Why Methane?

• Di-Methyl Hydrazine like all hydrazine-based fuels, is said to be highly toxic and cancer-causing.
• Globally, governments are keen on banning hydrazine.
• Besides, methane beats hydrazine on every other count.
• Apart from being non-toxic, it has a higher specific impulse which means one kg of the gas can life one kg of mass for a longer time.
• Methane, which can be synthesized with water and carbon dioxide in space, is often described as the space fuel of the future.
• It is easy to store, does not leave a residue upon burning, less bulky, and, importantly, can be synthesized up in space.
• Methane-fired engines need an igniter to start the fire.
• Hydrazine fuels are hypergolic, which means they start burning on their own upon coming in contact with oxygen.

Rocket Engine Development:

• Mumbai-based start-up Manastu Space is developing a propulsion system that will use Hydrogen peroxide as fuel.
• Currently, Manastu’s engines are meant for steering satellites in orbit but they can be scaled up to power launch vehicles.
• According to the company, the space industry started with Hydrogen peroxide, but moved to a ‘better’ hydrazine.
• But Manastu has developed a chemical additive, which it is trying to patent — the additive will enable Hydrogen peroxide to elbow hydrazine out of the competition.