Tham khảo tài liệu 'mems and microstructures in aerospace applications - robert osiander et al (eds) part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 18 MEMS and Microstructures in Aerospace Applications FIGURE 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. JWST Microshutter Array NASA s James Webb Space Telescope JWST is a large 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 Vision for Microtechnology Space Missions 19 composed of four 175 by 384 pixel modules. This device significantly enhances the capability of the JWST since the microshutters can be selectively configured to make highly efficient use of nearly the entire NIRSpec detector obtaining hundreds of object spectra simultaneously. Micromachined out of a silicon nitride membrane this device as shown in Figure and Figure consists of a 2-D array of
