<P> Rocket propellant is either a high oxygen containing fuel or a mixture of fuel plus oxidant, whose combustion takes place, in a definite and controlled manner with the evolution of a huge volume of gas . In the rocket engine, the propellant is burnt in the combustion chamber and the hot jet of gases (usually at very high pressures, with combustion temperatures approaching 3000K) escapes through the nozzle at very high velocity . </P> <P> Rocket propellant is a material used by a rocket as, or to produce in a chemical reaction, the reaction mass (propulsive mass) that is ejected, typically with very high speed, from a rocket engine to produce thrust, and thus provide spacecraft propulsion . Each rocket type requires different kind of propellant: chemical rockets require propellants capable of undergoing exothermic chemical reactions, which provide the energy to accelerate the resulting gases through the nozzle . Thermal rockets instead use inert propellants of low molecular weight that are chemically compatible with the heating mechanism at high temperatures, while cold gas thrusters use pressurized, easily stored inert gases . Electric propulsion requires propellants that are easily ionized or made into plasma, and in the extreme case of nuclear pulse propulsion the propellant consists of many small, non-weapon nuclear explosives of which the resulting shock wave of propels the spacecraft away from the explosive, thereby creating propulsion . One such spacecraft was designed (but never built), being dubbed "Project Orion" (not to be confused with the NASA Orion spacecraft). </P>

What is the name of fuel used in rocket