JWST microshutter array system and beyond

Abstract

We have developed the Microshutter Array (MSA) system at NASA Goddard Space Flight Center (GSFC) as a multi-object aperture array for the Near Infrared Spectrograph (NIRSpec) instrument on the James Webb Space Telescope (JWST). The MSA system will enable NIRSpec to simultaneously obtain spectra from more than 100 targets, which, in turn, increases instrument efficiency one-hundred fold. Consequently, this system represents one of the three major innovations on the JWST, which has been selected by the National Research Council's 2001 decadal survey as the top-ranked space-based mission and is scheduled to be the successor to the Hubble Space Telescope. Furthermore, the MSA system will be one of the first MEMS devices serving observation missions in space. Microshutters are designed for the selective transmission of light with high efficiency and contrast and feature torsion hinges, light shields, deep-reactive ion-etched silicon windows, magnetic actuation, and electrostatic latching and addressing. Complete MSA quadrant assemblies consisting of 365 x 181 microshutters have been successfully fabricated. The assemblies have passed a series of critical reviews, which include programmable 2-D addressing, life tests, optical contrast tests, and environmental tests, required by the design specifications of JWST. Both the MSA and NIRSpec will be delivered to ESA for final assembly, and JWST is scheduled to launch in 2014. During final assembly and testing of the MSA system, we have begun to develop the Next Generation Microshutter Arrays (NGMSA) for future telescopes. These telescopes will require a much larger field of view than JWST's, and we discuss strategies for fabrication of a proof-of-concept NGMSA which will be modular in design and electrostatically actuated.