JWST Update: MIRI Instrument Chilling Out

Apr 13, 2022 | Daily Space, JWST

IMAGE: By necessity, MIRI’s detectors are built using a special formulation of Arsenic-doped Silicon (Si:As), which need to be at a temperature of less than 7 kelvins to operate properly. This temperature is not possible by passive means alone, so Webb carries a “cryocooler” that is dedicated to cooling MIRI’s detectors. CREDIT: NASA/JPL-Caltech

A while ago, we provided an update on the optical alignment of the different instruments of the JWST to its telescope, with the exception of one – the Mid-Infrared Instrument or MIRI – because of the cold temperature needed. Here is more information on how exactly it will get down to its 7 Kelvin operating temperature.

Cold helium gas has been flowing over the instrument, but that’s only enough to get it down to 15 Kelvin. To finish cooling, MIRI has its own cryocooler, which takes the helium gas and squeezes it. The gas cools as it expands out of the cooler, cooling the MIRI instrument with it. This cooling is necessary to see exoplanets with temperatures thought to be similar to Earth. MIRI has four coronagraphs to precisely separate these planets from their host stars and characterize their atmospheres’ chemical makeup.

More Information

Webb’s Mid-Infrared Instrument Cooldown Continues (NASA)

Webb’s Cool View on How Stars, Planets Form (NASA)


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