Design of a Fine Guidance System for a Low-Earth Orbit Exoplanet Spectroscopy Mission

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Design of a Fine Guidance System for a Low-Earth Orbit Exoplanet Spectroscopy Mission

Arena, Claudio; (2021) Design of a Fine Guidance System for a Low-Earth Orbit Exoplanet Spectroscopy Mission. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Astronomical space missions require stable and fast target pointing to achieve their science objectives. To obtain high pointing stability, a Fine Guidance System (FGS) mechanism is normally used to provide fine pointing control. In this project, we analyse possible implementations of an FGS that uses piezoelectric actuators. This would not only allow for stable pointing but also allow for fast and reliable FGS operation. An optical setup was designed and built to test the proposed mechanism. Using a PID control loop, stability of up to 0.2 pixels on the focal plane was achieved. Considerable drifts that were observed without the FGS mechanism were eliminated using this control loop. The mechanical and thermal characteristics of the piezoelectric FGS mechanism were studied using finite element analysis to better characterise and optimise it. A software simulator was also produced to allow us to study the performance of centroid determination and the effects of an FGS mechanism in various situations. We conclude that a reliable and fast operating FGS can be implemented using piezoelectric actuators, allowing future astronomy missions to reach a stability of 5–10 milliarcseconds at a correction rate of up to a few hundred hertz. This stability, together with other advantages such as the mechanical simplicity of the system would make it ideal for space satellites such as the Twinkle satellite. It would also be an ideal system for many other low Earth orbit satellites, where many orbital disturbances need to be managed.

Type:	Thesis (Doctoral)
Qualification:	Ph.D
Title:	Design of a Fine Guidance System for a Low-Earth Orbit Exoplanet Spectroscopy Mission
Event:	UCL (University College London)
Open access status:	An open access version is available from UCL Discovery
Language:	English
Additional information:	Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
Keywords:	Fine Guidance System, FGS, Piezoelectric
UCL classification:	UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI:	https://discovery.ucl.ac.uk/id/eprint/10140068