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 manuevers, 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
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