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The NIRSpec (Near-Infrared Spectrograph) is one of the four scientific instruments which will be flown on the James Webb Space Telescope (JWST). The JWST is the follow-on mission to the Hubble Space Telescope (HST) and is developed to receive more information about the origins of the universe by observing infrared light from the first stars and galaxies. In comparison to HST, its instruments will allow looking further back in time and will study the so-called Dark Ages during which the universe was opaque, about 150 to 800 million years after the Big Bang. The NIRSpec instrument is a multi-object spectrograph and is capable of simultaneously measuring the near-infrared spectrum of up to 100 objects like stars or galaxies with low, medium and high spectral resolutions. The observations are performed in a 3 arcmin × 3 arcmin field of view over the wavelength range from 0.6 µm to 5.0 µm. It also features a set of slits and an aperture for high contrast spectroscopy of individual sources, as well as an integral-field unit (IFU) for 3D spectroscopy. The instrument is a contribution of the European Space Agency (ESA) and is built by Astrium together with a group of European subcontractors. == Overview == The JWST main science themes are: * First light and reionization * the assembly of galaxies, * the birth of stars and protoplanetary systems * the birth of planetary systems and the origins of life The NIRSpec instrument operates at -235 °C and utilizes a cryogenic cooling system for its mirrors. The mirror mounts and the optical bench base plate all manufactured out of silicon carbide ceramic SiC100. The instrument size is approximately and weighs including 100 kg of silicon carbide. The operation of the instrument is performed with three electronic boxes. NIRSpec includes 4 mechanisms which are: * the Filter Wheel Assembly (FWA) - 8 positions, carrying 4 long pass filters for science, 2 broadband filters for target acquisition, one closed and one open position * the Refocus Mechanism Assembly (RMA) - carrying 2 mirrors for instrument refocusing * the Micro Shutter Assembly (MSA) - for multi-object spectroscopy but also carrying the fixed slits and IFU aperture * the Grating Wheel Assembly (GWA) - 8 positions, carrying 6 gratings and one prism for science and one mirror for target acquisition Further NIRSpec includes two electro-optical assemblies which are: * Calibration Assembly (CAA) - carrying 11 illumination sources and an integrating sphere; for instrument internal spectral and flat-field calibration * Focal Plane Assembly (FPA) - includes the focal plane which consists of 2 sensor chip assemblies And finally the Integral Field Unit (IFU) image slicer, used in the instrument IFU mode. The optical path is represented by the following silicon carbide mirror assemblies: * the Coupling Optics Assembly - which couples the light from the JWST telescope into NIRSpec * the Fore Optics TMA (FOR) - which provides the intermediate focal plane for the MSA * the Collimator Optics TMA (COL) - collimating the light onto the Grating Wheel dispersive element * the Camera Optics TMA (CAM) - which finally images the spectra on the detector 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「NIRSpec (Near-Infrared Spectrograph)」の詳細全文を読む スポンサード リンク
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