Space Propulsion

This article presents the concept of space Propulsion, i.e. any system making it possible to move a space vehicle that it is ground towards space or directly in space for changes of terrestrial orbit or trajectories interplanetary.
Cela includes the means of propulsion of the space vehicles (rocket S, satellite S, probes) or the systems of Contrôle of orbit and altitude.

Principle

The general principle of the space propulsion rests, with some exceptions, on the exchange of Quantité of movement between the Matière ejected and the machine to be propelled. The Bilan of momentum is written for the machine:

$dP=dm\; \backslash cdot\; v\_e$

where dP is variation of momentum and v_e the Speed of ejection of the matter.

This variation is translated, by using the second law of Newton applied to the machine, by a force being exerted on the engin :

$F\_p=\; \backslash \; frac\; \{dP\}\; \{dt\}\; =\; \backslash \; dowry\; m\; \backslash ,\; v\_e$

where F_p is the force applied to the machine and ^{$\backslash \; dowry\; m$} the ejected matter flow.

Performance

In order to be able to classify and compare the various types of propulsion, a criterion of performance was established: the specific Impulse. It is defined by:

$I\_\; \{sp\}\; =\; \backslash \; frac\; \{F\}\; \{\backslash \; dowry\; m\; \backslash ,\; g\_0\}$

where F is the Poussée provided by the propulsion, ^{$\backslash \; dowry\; m$} the ejected flow of matter and g₀ the Accélération due to the field of gravity, presumedly constant near the surface of a planet.

Structure of a space propelling system

The following abstract structure can apply in a general way to the various types of engines:

Classification of the various types of propulsion

The classification of the various types of propulsion can be done in three groups according to the level of necessary technology of development (to refer to the concepts of TRL and SRL). This classification contains nevertheless a share of subjectivity and can thus be prone to discussion. In addition, of the combinations can intervene between the various types of propulsion.

Traditional propulsion

• cold gas
• solid liquid chemical Propulsion
• chemical Propulsion

Advanced propulsion

• hybrid space Propulsion
• nuclear propulsion
• electric propulsion: Propellent magnetoplasmadynamic, propellent ionic with bombardment, SPT, VASIMR.
• solar Propulsion
• Scramjet
• Propulsion with pulsated detonation (PDE)
• laser Propulsion
• veil (Photovoile, magnetic Veil,…)

Exotic propulsion

• MHD
• Antimatter
• space Elevator
• tethers
• photonic Propulsion

See too

• Rocket engine

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