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18 MEMS and Microstructures in Aerospace Applications

FIGURE 2.2 The NMP ST5 MEMS thermal louver actuator block with shutter array.
(Source: JHU/APL.)

balance. One potential solution to this design problem is to employ the MEMS
micromachined shutters to create, in essence, a variable emittance coating (VEC).
Such a VEC yields changes in the emissivity of a thermal control surface to allow
the radiative heat transfer rate to be modulated as needed for various spacecraft
operational scenarios. In the case of the ST5 flight experiment, the JHU/APL
MEMS thermal shutters will be exercised to perform adaptive thermal control of
the spacecraft by varying the effective emissivity of the radiator surface.

2.2.2 JWST MICROSHUTTER ARRAY
NASA’s James Webb Space Telescope (JWST) is a large (6.5-m primary mirror
diameter) infrared-optimized space telescope scheduled for launch in 2011. JWST
is designed to study the earliest galaxies and some of the first stars formed after the
Big Bang. When operational, this infrared observatory will take the place of the
Hubble Space Telescope and will be used to study the universe at the important but
previously unobserved epoch of galaxy formation. Over the past several years,
scientists and technologists at NASA GSFC have developed a large format
MEMS-based microshutter array that is ultimately intended for use in the JWST
near infrared spectrometer (NIRSpec) instrument. It will serve as a programmable
field selector for the spectrometer and the complete microshutter system will be

© 2006 by Taylor & Francis Group, LLC