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8 MEMS and Microstructures in Aerospace Applications

An entire chapter, Chapter 5, deals with radiation-induced performance deg-
radation of MEMS. It begins with a discussion on the space radiation environment
encountered in any space mission. The radiation environment relevant to MEMS
consists primarily of energetic particles that originate in either the sun (solar
particles) or in deep space (cosmic rays). Spatial and temporal variations in the
particle densities are described, together with the spectral distribution. This is
followed by a detailed discussion on the mechanisms responsible for radiation
damage that give rise to total ionizing dose, displacement damage dose, and single
event effects. The background information serves as a basis for understanding the
radiation degradation of specific MEMS, including accelerometers, microengines,
digital mirror devices, and RF relays. The chapter concludes by suggesting some
approaches for mitigating the effects of radiation damage.

1.4.2 MEMS IN SPACE SYSTEMS AND INSTRUMENTATION
Over the past two decades, micro- or nanoelectromechanical systems (MEMS and
NEMS) and other micronanotechnologies (MNT) have become the subjects of
active research and development in a broad spectrum of academic and industrial
settings. From a space systems perspective, these technologies promise exactly
what space applications need, that is, high-capability devices and systems with
low mass and low power consumption. Yet, very few of these technologies have
been flown or are currently in the process of development for flight. Chapter 6
examines some of the underlying reasons for the relatively limited infusion of these
exciting technologies in space applications. A few case studies of the ‘‘success
stories’’ are considered. Finally, mechanisms for rapidly and cost-effectively over-
coming the barriers to infusion of new technologies are suggested. As evidenced by
the numerous MNT-based devices and systems described in this and other chapters
of this book, one is essentially limited only by one’s imagination in terms of the
diversity of space applications, and consequently, the types of MNT-based com-
ponents and systems that could be developed for these applications. Although most
MNT concepts have had their birthplace in silicon-integrated circuit technology, the
field has very rapidly expanded into a multidisciplinary arena, exploiting novel
physical, chemical, and biological phenomena, and utilizing a broad and diverse
range of materials systems.
Chapter 7 discusses science instrumentation applications for microtechnologies.
The size and weight reduction offered by micromachining approaches has multiple
insertion points in the development of spacecraft science instrumentation. The use
of MEMS technology is particularly attractive where it provides avenues for the
reduction of mission cost without the sacrifice of mission capability. Smaller
instruments, such as nuclear magnetic resonance MEMS probes to investigate en-
vironmental conditions, can essentially reduce the weight and size of planetary
landers, and thereby reduce launch costs. MEMS technology can generate new
capabilities such as the multiple object spectrometers developed for the James
Webb Space Telescope, which is based on MEMS shutter arrays. New missions can
be envisioned that use a large number of small satellites with micromachined

© 2006 by Taylor & Francis Group, LLC