S.1 Spacecraft Propulsion Systems Chapter 1: Introduction to ...

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Potential increase in performance of existing space propulsion systems – Chemical Propulsion
For chemical propulsion high performance, i.e. high values of ''System-specific Impulse',
Issp resulting in low values of ‘propulsion system mass fraction’, is primarily dictated by
maximum values of 'Thruster-specific Impulse', Isp (ve); for details see Issp-Program.
The performance of state-of the-art spacecraft engines operating with cold and hot gas,
however, can be considered near to the theoretical limit for actual space storable propellant
combinations.
The emerging class of micro-and nanospacecraft require miniaturisation of the propulsion
system with help of ‘Microelectromechanical System’ (MEMS) technology for acceptable
values of Issp, in order to achieve a low ‘non-impulse system mass factor’ x.
With increasing interest in environmental and safety issues, non-toxic monopropellant
systems are under development, as already presented in Chapter 3.
Consequently, actual designs of chemical spacecraft propulsion systems are well
developed, but are being complemented by non-toxic monopropellant systems. The
emerging class of micro-and nanospacecraft requires ‘Microelectromechanical System’
(MEMS) technology for miniaturisation of the propulsion system.