Most NASA rockets are powered by liquid oxygen and hydrogen or solid chemicals, but NASA is currently working on alternatives such as this methane engine. Although it is still in an early stage of development and isn’t ready for space. But if the technology proves itself, methane engines like this one could eventually be key to deep space exploration. Methane (CH4), the principal component of natural gas, is abundant in the outer solar system. It can be harvested from Mars, Titan, Jupiter, and many other planets and moons. With fuel waiting at the destination, a rocket leaving Earth wouldn’t have to carry so much propellant, reducing the cost of a mission.