MID-INFRARED INSTRUMENT (MIRI)

The Mid-Infrared Instrument (MIRI) has both a camera and a spectrograph that sees light in the mid-infrared region of the electromagnetic spectrum, with wavelengths that are longer than our eyes see.

The optical module (OM), containing the imager, spectrometers, and coronagraphs, is within the JWST integrated science instrument module (ISIM) with a nominal 40K surrounding temperature. The OM and focal plane modules (FPMs) are brought to a lower temperature by a pulse-tube-based mechanical cooler, with compressors (CCA) and control electronics (CCE) in the spacecraft and refrigerant lines (RLDA) to bring cold gas to a Joule-Thompson (JT) expander near the OM. The instrument mechanisms are controlled by the instrument control electronics (ICE), and the focal planes are operated by the focal plane electronics (FPE), both of which are in region 2, a warm module placed near the ISIM.  

Credits: http://ircamera.as.arizona.edu

MIRI covers the wavelength range of 5 to 28 microns. Its sensitive detectors will allow it to see the redshifted light of distant galaxies, newly forming stars, and faintly visible comets as well as objects in the Kuiper Belt. MIRI's camera will provide wide-field, broadband imaging that will continue the breathtaking astrophotography that has made Hubble so universally admired. The spectrograph will enable medium-resolution spectroscopy, providing new physical details of the distant objects it will observe. 

Installation of MIRI into the instrument module.
Credits: https://webb.nasa.gov

JWST Team Photo with Completed Flight Instrument module
Credits: https://webb.nasa.gov

MIRI was built by the MIRI Consortium, a group that consists of scientists and engineers from European countries, a team from the Jet Propulsion Lab in California, and scientists from several U.S. institutions

The MIRI has three Arsenic-doped Silicon (Si: As) detector arrays. The camera module provides wide-field broadband imagery, and the spectrograph module provides medium-resolution spectroscopy over a smaller field of view compared to the imager. The nominal operating temperature for the MIRI is 7K. This level of cooling cannot be attained using the passive cooling provided by the Thermal Management Subsystem. Webb carries an innovative "cryocooler" that is dedicated to cooling MIRI detectors. Instead, there is a two-step process: A Pulse Tube precooler gets the instrument down to 18K, and a Joule-Thomson Loop heat exchanger knocks it down to 7K.

MIRI Engineering Diagram(Labeled)
Credits: https://webb.nasa.gov

MIRI Engineering Diagram
Credits: https://webb.nasa.gov