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MATTHIEU GASQUET SOLAR ORBITER: THERMAL ANALYSIS AND DESIGN OF AN EXTREME ULTRA VIOLET SPECTROMETER

MATTHIEU GASQUET
SOLAR ORBITER: THERMAL ANALYSIS AND DESIGN OF
AN EXTREME ULTRA VIOLET SPECTROMETER
SCHOOL OF ENGINEERING
MSC IN ASTRONAUTICS AND SPACE ENGINEERING
RESEARCH THESIS REPORT
SCHOOL OF ENGINEERING
MSc in Astronautics and Space Engineering
Research Thesis Report
2002
MATTHIEU GASQUET
SOLAR ORBITER: Thermal Analysis and Design of an Extreme
Ultra Violet Spectrometer
Supervisors:
Ms. Sam Heys
Mr. Eric Sawyer
Mr. Tom Bowling

Presented: September 2002
This thesis is submitted in partial fulfilment of the requirements for the Degree of MSc
in Astronautics and Space Engineering
© Cranfield University 2002. All rights reserved. No part of this publication may be
reproduced without the written permission of the copyright owner. i
Abstract

The Solar Orbiter, project funded by the European Space Agency, will be the first
spacecraft to go as close as 0.2 Astronomical Units from the Sun. It will allow
scientists to have a better understanding of the sun and in particularly of its
dynamics. The Rutherford Appleton Laboratory led a consortium to build an
Extreme Ultra-Violet spectrometer which will be embedded on the solar probe. This
instrument will provide information on plasma density, temperature, element/ion
abundances, flow speeds and the structure and evolution of atmospheric phenomena.
Because of the very severe thermal environment the probe will have to withstand, the
thermal design of this instrument has to be studied very carefully in order to control
accurately the temperature on board. The work described in this report is a pre-
analysis and design of some components of the spectrometer.
The goal of this task is mainly to study the thermal environment of the spacecraft and
to find the main keys of the thermal control strategy which will allows each device to
stay within its temperature requirements.
After a description of the available technological solutions to control the temperature
in a satellite and a definition of the temperature requirements, a preliminary thermal
analysis has been done on Excel in order to have a first idea of the radiator area
dedicated to the instrument when the heat load is maximum. Then many simulations
have been done on I-Deas and ESARAD/ESATAN, some thermal analysis software.
The aim of the strategy developed is to minimise heat transfer by radiation, increase
as much as possible the reflectivity of the spectrometer mirrors, and insulate the
spectrometer from the rest of the spacecraft by minimising the conductive heat
transfer between the spectrometer casing and the spacecraft. For mass and reliability
reasons, this strategy is based on passive control systems such as Multi-Layers
Insulation or thermal coatings.
With this strategy, it seems possible to keep the temperatures within allowable limits,
but those temperatures are still oscillating a lot. That could be a problem for the
thermal stability of the structure. One possibility to solve it would be to use some
more complex thermal control devices such as thermal switches, variable
conductance heat pipes, or louvers.
ii
Contents

Abstract .............................................................................................................................. i
Contents ............................................................................................................................ii
List of Figures ................................................................................................................... v
List of Tables ..................................................................................................................vii
Nomenclature................................................................................................................... ix
1.
INTRODUCTION .................................................................................................... 1
1.1
Mission Description .......................................................................................... 1
1.2
The work project ............................................................................................... 5
1.2.1
Presentation............................................................................................... 5
1.2.2
Objectives of the thermal analysis ............................................................ 5
1.2.3
Scope of the thesis .................................................................................... 6
1.2.4
Work planning .......................................................................................... 6
2.
The Extreme Ultra-Violet Spectrometer................................................................... 8
2.1
Scientific objectives of the instrument.............................................................. 8
2.2
Technical requirements..................................................................................... 8
2.2.1
Mass budget .............................................................................................. 9
2.2.2
Miscellaneous ........................................................................................... 9
2.2.3
Particle environment ............................................................................... 10
2.2.4
Contamination problems......................................................................... 10
2.2.5
Materials ................................................................................................. 10
2.2.6
Thermal requirements ............................................................................. 13
2.3
Optical design possibilities ............................................................................. 13
2.3.1
Optical designs........................................................................................ 13
2.3.1.1
The off axis telescope ......................................................................... 14
2.3.1.2
The grazing incidence telescope ......................................................... 15
2.3.2
Applied coatings ..................................................................................... 17
2.4
Review of thermal control systems and devices ............................................. 18
2.4.1
Passive thermal control devices .............................................................. 19
2.4.1.1
Multi Layers Insulation (MLI)............................................................ 19
2.4.1.2
Radiators ............................................................................................. 20
2.4.1.3
Thermal control coatings .................................................................... 21
2.4.1.4
Conductive tapes and joints ................................................................ 21
2.4.1.5
Phase Change Materials (PCM).......................................................... 22
2.4.1.6
Thermal doublers ................................................................................ 23
2.4.2
Active Thermal control devices .............................................................. 23
iii
2.4.2.1
Louvers ............................................................................................... 23
2.4.2.2
Heat pipes ........................................................................................... 24
2.4.2.3
Heaters ................................................................................................ 25
2.4.2.4
Thermal switches ................................................................................ 26
2.4.2.5
Pumped-loop systems ......................................................................... 26
2.4.2.6
Heat exchangers .................................................................................. 27
2.4.2.7
Cold plate ............................................................................................ 27
3.
Preliminary thermal analysis................................................................................... 28
3.1
Assumptions and description of the model..................................................... 28
3.2
Excel calculation process................................................................................ 28
3.2.1
Grazing incidence option ........................................................................ 28
3.2.2
Off axis option ........................................................................................ 32
3.2.3
Formulae ................................................................................................. 34
3.3
Results, analysis, feasibility, model precision ................................................ 35
4.
Transient thermal analysis ...................................................................................... 39
4.1
The thermal environment................................................................................ 39
4.2
Presentation of the softwares ..............