The James Webb Space Telescope (JWST) carries within its narrative a blend of favorable and unfavorable tidings. On the downside, a hiccup has befallen one of its instruments, christened the Mid-Infrared Instrument, or MIRI. Nonetheless, before trepidation takes its hold, on the bright side, the JWST remains in a state of contented well-being, robustly poised to continue unraveling the concealed intricacies of the cosmos.
To delve into specifics, during the month of April, the JWST team disclosed an irregularity involving one of MIRI’s four operational modes. This anomaly manifested as a decrease in the quantity of light registered by the instrument. However, following a diligent inquiry into the matter, NASA has been prompt to assure us that this alteration does not cast a shadow of risk upon MIRI’s scientific capabilities. “The instrument’s integrity remains unimpaired,” NASA emphasized in a recent blog post issued on August 24th. It’s worth noting, though, that the anomaly might necessitate an adjustment in the duration of exposure when transitioning to the affected operational mode.
The focal point of this matter resides within a mode labeled Medium-Resolution Spectroscopy (MRS), meticulously calibrated to capture infrared data emanating from remote pockets of the cosmos, accompanied by wavelengths spanning from 5 to 28.5 microns. This range, as elucidated by NASA, encompasses emissions from molecules and particulate matter, rendering MRS especially apt for discerning phenomena like the emergence of planet-forming disks. However, the crux of the blog post sheds light on the specificity of the diminished signal, which pertains to MIRI’s imaging endeavors specifically within the extended wavelength regime.
Amidst this backdrop, MIRI’s other mode, known as Low-Resolution Spectrography, attuned to wavelengths ranging from 5 to 12 microns, a realm often associated with the surfaces of objects such as planets, continues its operational duties without hindrance, as verified by the team. Concurrently, a fourth mode, namely Coronagraphic Imaging, remains the subject of ongoing investigation. This particular mode’s raison d’être lies in the direct detection of exoplanets and circumstellar dust disks encircling their host stars. Achieving this feat involves a process known as coronagraphy, wherein the suppression of light from a specific source serves as the conduit for gathering insights about neighboring sources.
The JWST team, ever vigilant, also corroborates that the observatory’s overall condition is one of “excellent health.” This assertion extends to the suite of other scientific instruments housed within the JWST, namely its Near-Infrared Camera (NIRCam), Near-Infrared Spectrograph (NIRSpec), Near-Infrared Imager and Slitless Spectrograph (NIRISS), and Fine Guidance Sensor (FGS).