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128 MEMS and Microstructures in Aerospace Applications

to be built with very small thermal conduction paths and small thermal capacities.
Such devices can be used in microbolometers and allow the detection and imaging
of particles and electromagnetic radiation from x-rays to mm-waves with very high
resolution. The technology allows small shutters or mirrors to be built, which can
block or deflect light from a single pixel in a telescope such as the James Webb
Space Telescope (JWST), the designated replacement for the Hubble Space Tele-
scope (HST). The small dimensions also allow for building ultrasmall plasma
detectors and mass spectrometers with sufficient electric fields at very small supply
voltages.
Science instruments can be divided into different groups based on the mission.
For earth and solar sciences, and in some respects, planetary and deep space
missions, the detection, investigation, and mapping of electromagnetic fields,
particle distributions, and gravitational fields are important. Instruments to be
employed are plasma and ion detectors, magnetometers, and accelerometers.
There are a number of MEMS designs and prototype systems available for these
instruments. 1,2 For the observation of stars and planetary emissions, telescopes and
spectrometers are of importance. Here MEMS instruments can be used as the
detector (e.g., a bolometer), or can improve the operation of the telescopes as in
the case of the JWST. 3,4 For planetary exploration, MEMS instruments can help
reduce the size and weight of planetary landers. For these applications, instruments
such as hygrometers, seismometers, mass spectrometers, and micromagnetic
resonance systems such as the magnetic resonance force microscope have been
designed and fabricated and could be used for robotic and human exploration. 4,5 A
further set of instruments can be applied for human space exploration, all those
which monitor and measure the environmental conditions within the spacecraft or
habitat. The applications cover the range of all medical diagnosis instrumentations,
environmental monitors such as oxygen detectors, monitors for soil quality in
space-based growth chambers, etc. This chapter will provide an overview of
instruments with the capability or development goal to be used in spacecraft
applications.

7.2 ELECTROMAGNETIC FIELD AND PARTICLE DETECTION
FOR SPACE SCIENCE
MEMS-based detectors for electromagnetic fields and particles are expected to be
important for future planetary and deep space missions, and their use in Earth-
1
orbiting satellites is planned for the near future. A mission concept which relies
totally on the basic advantages of MEMS instruments — light weight, batch-
processes, inexpensive instruments, and satellites in large numbers — is the map-
ping of ion distributions or magnetic fields. This goal can only be achieved with a
large number of microsatellites, which can simultaneously map the fields at differ-
ent positions in space. One example for such a mapping mission is the magneto-
6
spheric constellation mission, MagCon. It consists of a constellation of 50 small
satellites distributed in the domain of the near-Earth plasma sheet. The mission will

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