FEEP Micro-propulsion Subsystem for scientific missions

Paper number

IAC-08.C4.4.5

Author

Mr. Paolo GALANTINI, Galileo Avionica S.p.A., Italy

Coauthor

Mr. Luca Ceruti, Galileo Avionica S.p.A., Italy

Coauthor

Mr. Aldo Polli, Galileo Avionica S.p.A., Italy

Coauthor

Mr. Davide Nicolini, European Space Agency (ESA), The Netherlands

Year

2008

Abstract

Field Emission Electrical Propulsion (FEEP) is the key enabling technology in space applications requiring very high controllability at low thrust level (e.g. drag-free experiments, fine pointing/attitude control or formation flying).
In this perspective, FEEP technology is mandatory in the frame of breakthrough mission like LISA (Laser Interferometer Space Antenna). 
It is a mission jointly sponsored by the European Space Agency (ESA) and the National Aeronautics Space Administration (NASA), with the primary aim to detect and measure gravitational waves expected to be emitted by distant galactic sources, such as black holes, through an advanced system of laser interferometry.

LISA consists of three spacecrafts freely flying five million kilometres apart, in an equilateral triangle, used as targets by a Laser Interferometer.
In order to achieve the extremely high spacecrafts positioning accuracy necessary to meet the mission objective, ultra-low thrust level (few µN) at very high controllability (about 0.1 µN) with noise free behaviour is required. This is provided by a FEEP subsystem made of:

- FEEP Cluster Assembly (FCA), made of FEEP Thruster Assemblies, including propellant reservoir, providing thrust to the required vector directions. They are individually commanded and operate in hot redundancy.

- Neutralizer Assembly (NA), made of two, cold redundant Neutralizers, necessary to nullify the spacecraft unbalance due to ion thruster operation. 

- Power Control Unit (PCU), the electronic unit interfacing the spacecraft (Power and TC/TM tasks) and providing power and control to both FEEP Cluster and Neutralizer assemblies.
 
The PCU provides a fundamental contribute in the propulsion performances in term of resolution, accuracy, controllability, noise and so on. 
Moreover it has been conceived to be flexible at the maximum extent in order to supply and control any of the two FEEP technology candidates currently under development/qualification in Europe (one using a slit-shaped emitter and Cesium as propellant and a second with a cluster of needles and Indium as propellant).
 
This paper presents an up-to-date status of the common PCU developed by Galileo Avionica to supply and control FEEP micro-propulsion subsystems for different thruster technology and mission scenarios as well as the overall subsystem design drivers and the trade-offs performed leading to the final solutions implemented.
After a detailed description of each single constituent of the subsystem (namely Thruster assemblies grouped into Thruster Clusters, Neutralizers and PPCUs), a summary of the test results from the campaign conducted up to date and the main achievements at subsystem level are also presented.

Abstract document

IAC-08.C4.4.5.pdf

Manuscript document

IAC-08.C4.4.5.pdf (🔒 authorized access only).

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