Dual mode propulsion rocket
Encyclopedia
Dual mode propulsion
systems combine the high efficiency of bipropellant rockets with the reliability and simplicity of monopropellant rocket
s. Dual mode systems are either hydrazine
/N2O4, or MMH/hydrogen 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 oxidizer, and conducts the remainder of its mission in a simple, predictable monopropellant
fashion.
Spacecraft propulsion
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the...
systems combine the high efficiency of bipropellant rockets with the reliability and simplicity of monopropellant rocket
Monopropellant rocket
A monopropellant rocket is a rocket that uses a single chemical as its propellant.-Chemical-reaction monopropellant rockets:...
s. Dual mode systems are either hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
/N2O4, or MMH/hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
(the former is much more common). Typically, this system works as follows: During the initial high-impulse orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
-raising maneuvers, the system operates in a bipropellant fashion, providing high thrust
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....
at high efficiency; when it arrives on orbit, it closes off either the fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
or oxidizer, and conducts the remainder of its mission in a simple, predictable monopropellant
fashion.