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MIRI is the mid-IR instrument for the James Webb Space Telescope and provides imaging, coronography and integral field spectroscopy over the 5-28µm wavelength range. MIRI is the only instrument which is cooled to 7K by a dedicated cooler, much lower than the passively cooled 40K of the rest of JWST, which introduces unique challenges. The paper will describe the key features of the overall instrument design. The flight model design of the MIRI Optical System is completed, with hardware now in manufacture across Europe and the USA, while the MIRI Cooler System is at PDR level development. A brief description of how the different development stages of the optical and cooling systems are accommodated is provided, but the paper largely describes progress with the MIRI Optical System. We report the current status of the development and provide an overview of the results from the qualification and test programme.

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The Near-Infrared Spectrograph (NIRSpec) on board of the James Webb Space Telescope will be the first multiobject spectrograph in space offering ∼250,000 configurable micro-shutters, apart from being equipped with an integral field unit and fixed slits. At its heart, the NIRSpec grating wheel assembly is a cryogenic mechanism equipped with six dispersion gratings, a prism, and a mirror. The finite angular positioning repeatability of the wheel causes small but measurable displacements of the light beam on the focal plane, precluding a static solution to predict the light-path. To address that, two magneto-resistive position sensors are used to measure the tip and tilt displacement of the selected GWA element each time the wheel is rotated. The calibration of these sensors is a crucial component of the model-based approach used for NIRSpec for calibration, spectral extraction, and target placement in the micro-shutters. In this paper, we present the results of the evolution of the GWA sensors performance and calibration from ground to space environments.

We describe the on-orbit performance of the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) aboard the Hubble Space Telescope (HST) following the installation of the NICMOS Cooling System (NCS). NICMOS is operated at a higher temperature (∼77 K) than in the previous observing 1997-1998 period (∼62 K). Due to the higher operating temperature, the detector QE is higher, while the well depth is less. The spatial structure of the flat field response remained essentially unchanged. We will show the effects of operating at the higher temperature and present current NICMOS calibration images. In addition, we present an overview of on-orbit testing and report on the re-enabling of NICMOS.