Dual mode propulsion rocket
Dual mode propulsion systems combine the high efficiency of bipropellant rockets with the reliability and simplicity of monopropellant rockets. Dual mode systems are either
hydrazine/N
2O
4, or MMH/
peroxide (the former is much more common). Typically, this system works as follows: During the initial high-
impulse orbit-raising maneuvers, the system operates in a bipropellant fashion, providing high
thrust at high efficiency; when it arrives on orbit, it closes off either the
fuel or oxidier, and conducts the remainder of its mission in a simple, predictable monopropellant
fashion.
See also: spacecraft propulsion