Problem Detected on the James Webb Space Telescope – MIRI Anomaly

Telescope in space by James Webb Animation of MIRI Spectroscopy: The beam of light coming from the telescope is then shown in deep blue coming into the instrument through the pick-off mirror, which is at the top of the instrument and acts like a periscope. 

The light is then sent to the bottom of the instruments, where a set of four spectroscopic modules are located, by a series of mirrors. Once it gets there, the light beam is split into four beams that correspond to different parts of the mid-infrared region. This is done by optical elements called dichroic. Each beam goes into its own integral field unit,

MIRI Anomaly

where the light from the whole field of view is split and reshaped into spectra. In order to do this, the light has to be folded, bounced, and split a lot. This is likely one of Webb’s most complicated light paths. 
Light from each beam is spread out by gratings to make spectra, which are then shown on 2 MIRI detectors to end this amazing journey (2 beams per detector). a fantastic piece of work!Credit: ESA/ATG medialab

The Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope has four ways to look at the sky. On August 24, when setting up for scientific observation, a part of one of these modes, called medium-resolution spectroscopy (MRS), showed what looks like more friction. This part is a grating wheel that lets astronomers choose between short,

medium, and long wavelengths when they use the MRS mode to make observations. After initial health checks and investigations into the problem, on September 6, an “anomaly review board” was put together to figure out what the best next step should be. The Webb team has stopped scheduling observations with this particular mode of observation while they keep studying how it works.

Problem Detected on the James

They are also working on plans to get MRS observations back on track as soon as possible. The observatory is in good health, and MIRI’s other three observing modes – imaging, low-resolution spectroscopy, and coronagraphy – are working normally and can still be used for scientific observations. The Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (Webb) sees light with longer wavelengths than our eyes can see.

Scientists can use imaging, spectroscopy, and coronagraphy, three different ways to look at the Sun, to help Webb achieve all of his scientific goals, from looking at our solar system and other planetary systems to studying the early Universe.

In order to fit all of these modes into a single instrument, engineers built a complicated optical system in which light from Webb’s telescope goes through a complicated 3D path before reaching MIRI’s detectors.

This picture made by an artist shows this path for MIRI’s imaging mode, which can take pictures and take pictures of the sun’s corona. There is also a simple spectrograph in it. First, we look at its mechanical structure, which is made up of three pairs of protruding carbon fiber struts that will connect it to the back of Webb’s instrument compartment.

The light from the telescope, shown in deep blue, is sent through the pick-off mirror, which acts like a periscope, and into MIRI’s imaging module. Inside the instrument, a set of mirrors reshapes the light beam and sends it in a different direction until it reaches a filter wheel. Here, the desired range of mid-infrared wavelengths is chosen from a set of 18 filters, each of which has a specific job (the beam takes on a light blue color in the animation).


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