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5 Space Radiation

Effects and

Microelectromechanical

Systems

Stephen P. Buchner

CONTENTS

5.1 Introduction.................................................................................................... 83
5.1.1 The Space Radiation Environment.................................................... 84
5.1.2 Earth Orbits ........................................................................................ 86
5.1.3 Interplanetary Space........................................................................... 91
5.1.4 Planetary Missions ............................................................................. 91
5.2 Radiation Effects ........................................................................................... 91
5.2.1 Space Radiation Interaction with Materials and
Devices (Ionization)........................................................................... 93
5.2.2 Space Radiation Interaction with Materials and Devices
(Displacement Damage)..................................................................... 96
5.2.3 Radiation Testing of MEMS.............................................................. 97
5.3 Examples of Radiation Effects in MEMS .................................................... 97
5.3.1 Accelerometer .................................................................................... 98
5.3.2 Microengine with Comb Drive and Gears ...................................... 101
5.3.3 RF Relay........................................................................................... 103
5.3.4 Digital Mirror Device ...................................................................... 105
5.4 Mitigation of Radiation Effects in MEMS ................................................. 107
5.5 Conclusion ................................................................................................... 107
References ........................................................................................................... 108

5.1 INTRODUCTION
The space environment presents a variety of hazards for spacecraft. Not only are
there extremes of temperature and pressure to contend with, but the spacecraft must
also withstand a constant onslaught of energetic ionized particles and photons that
can damage both the spacecraft and its payload. Atomic oxygen (AO) poses a
serious hazard because it corrodes materials with which it comes into contact,
causing surface erosion and contamination of the spacecraft. High-energy photons

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