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Osiander / MEMS and microstructures in Aerospace applications DK3181_c009 Final Proof page 183 1.9.2005 12:07pm

9 Microsystems in

Spacecraft Thermal

Control

Theodore D. Swanson and Philip T. Chen

CONTENTS

9.1 Introduction.................................................................................................. 183
9.2 Principles of Heat Transfer ......................................................................... 184
9.2.1 Conduction ....................................................................................... 185
9.2.2 Convection........................................................................................ 186
9.2.3 Radiation .......................................................................................... 186
9.3 Spacecraft Thermal Control ........................................................................ 188
9.3.1 Spacecraft Thermal Control Hardware............................................ 188
9.3.2 Heat Transfer in Space..................................................................... 189
9.4 MEMS Thermal Control Applications........................................................ 191
9.4.1 Thermal Sensors............................................................................... 191
9.4.2 MEMS Louvers and Shutters........................................................... 192
9.4.3 MEMS Thermal Switch ................................................................... 195
9.4.4 Microheat Pipes................................................................................ 197
9.4.5 MEMS Pumped Liquid Cooling System......................................... 198
9.4.6 MEMS Stirling Cooler..................................................................... 199
9.4.7 Issues with a MEMS Thermal Control............................................ 200
9.5 Conclusion ................................................................................................... 201
References............................................................................................................. 201

9.1 INTRODUCTION

Thermal control systems (TCS) are an integral part of all spacecraft and instru-
ments. Thermal engineers design TCS to allow spacecraft to function properly on-
1
orbit. In TCS design, both passive and active thermal control methods may be
applied. Passive thermal control methods are commonly adopted for their relatively
low cost and reliability, and are adequate for most applications. When passive
thermal control methods are insufficient to meet the mission thermal requirements,
active thermal control methods are warranted. Active thermal control methods may
be more effective in meeting stringent thermal requirements. For example, many
emerging sensor applications require very tight temperature control (to within 1 K)

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