Problem detected on the James Webb Space Telescope – MIRI anomaly

Animation of Webb MIRI spectroscopy

James Webb Space Telescope MIRI spectroscopy animation: The beam of light from the telescope is then shown in deep blue entering the instrument through the detection mirror located at the top of the instrument and acting as a periscope.
Then, a series of mirrors redirects the light to the bottom of the instruments where there is a set of 4 spectroscopic modules. Once there, the beam of light is split by optical elements called dichroics into 4 beams corresponding to different parts of the mid-infrared region. Each beam enters its own integral field unit; these components split and reformat light from the entire field of view, ready to be dispersed into spectra. It requires the light to be bent, bounced, and split multiple times, making it probably one of Webb’s most complex light paths.
To complete this amazing journey, the light from each beam is dispersed by gratings, creating spectra which then project onto 2 MIRI detectors (2 beams per detector). An incredible feat of engineering! Credit: ESA/ATG medialab

Mid-Infrared Instrument Operations Update

The[{” attribute=””>Télescope spatial James WebbL’instrument à infrarouge moyen de (MIRI) dispose de quatre modes d’observation. Lors de la configuration d’une observation scientifique le 24 août, un mécanisme qui prend en charge l’un de ces modes, connu sous le nom de spectroscopie à résolution moyenne (MRS), a présenté ce qui semble être une friction accrue. Ce mécanisme est une roue à réseau qui permet aux astronomes de choisir entre des longueurs d’onde courtes, moyennes et longues lorsqu’ils effectuent des observations en utilisant le mode MRS. À la suite de bilans de santé préliminaires et d’enquêtes sur le problème, un comité d’examen des anomalies a été convoqué le 6 septembre pour évaluer la meilleure voie à suivre.

The Webb team has taken a break from planning sightings using this particular sighting mode while they continue to analyze its behavior. They are also currently developing strategies to resume MRS observations as soon as possible. The observatory is in good health and MIRI’s other three observation modes – imaging, low-resolution spectroscopy and coronagraphy – are functioning normally and remain available for scientific observations.

The Mid-Infrared Instrument (MIRI) of the James Webb Space Telescope (Webb) sees light in the mid-infrared region of the electromagnetic spectrum, at longer wavelengths than our eyes can see.

MIRI enables scientists to use several observational techniques: imaging, spectroscopy and coronagraphy to support all of Webb’s scientific goals, from observing our own solar system and other planetary systems to studying the primitive universe.

To pack all these modes into a single instrument, engineers designed a complex optical system in which light from Webb’s telescope follows a complex 3D path before finally reaching MIRI’s detectors.

This artist’s render shows this path for MIRI’s imaging mode, which offers imaging and coronagraphy capabilities. It also contains a simple spectrograph. We first look at its mechanical structure with its three pairs of carbon fiber struts that will attach it to Webb’s instrument compartment at the back of the telescope.

The detection mirror, acting as a periscope, receives light from the telescope, shown in deep blue, and directs it to MIRI’s imaging module. Inside the instrument, a system of mirrors reformats the light beam and redirects it until it reaches a filter wheel where the desired mid-infrared wavelength range is selected from a set of 18 different filters each with its own specific function (the beam takes on a light blue color in the animation).

Finally, another set of mirrors captures the light beam emerging from the filter wheel and recreates the image of the sky on MIRI’s detectors.

Credit: ESA/ATG medialab

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