The problem was discovered on the James Webb Space Telescope

Mid-infrared device operations update

The[{” attribute=””>James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) has four observing modes. During setup for a science observation on August 24, a mechanism that supports one of these modes, known as medium-resolution spectroscopy (MRS), exhibited what appears to be increased friction. This mechanism is a grating wheel that allows astronomers to select between short, medium, and longer wavelengths when making observations using the MRS mode. Following preliminary health checks and investigations into the issue, an anomaly review board was convened on September 6 to assess the best path forward.

The Webb team paused scheduling notes using this monitoring mode while continuing to analyze its behavior. They are also currently developing strategies to resume viewing MRS as soon as possible. The observatory is healthy and the other three MIRI monitoring modes – imaging, low-resolution spectroscopy, and coronagraph – operate normally and remain available for scientific observations.

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

MIRI allows scientists to use multiple observational technologies: imaging, spectroscopy, and chromatography to support the full range of Webb’s scientific goals, from observing our solar system and other planetary systems to studying the early universe.

To combine all of these modes into one instrument, the engineers designed a complex optical system in which the light coming from the Webb telescope follows a complex three-dimensional path before finally reaching the MIRI detectors.

This artist’s rendering shows the path to the MIRI capture mode, which provides imaging and chronograph capabilities. It also includes a simple spectrophotometer. We first look at the mechanical structure with three protruding pairs of carbon fiber trusses that will be attached to the Webb instrument compartment at the back of the telescope.

Acting like a binoculars, the pickup mirror receives the light from the telescope, shown in dark blue, and sends it to the image-processing unit at MIRI. Inside the device, a system of mirrors reshapes and redirects the light beam until it reaches the filter wheel where the desired range of mid-infrared wavelengths is chosen from a set of 18 different filters, each with its own function (beam takes on the light blue color in the animation) .

Finally, another set of mirrors takes the beam of light emerging from the filter wheel and reconstructs the image of the sky on the MIRI detectors.

Credit: ESA/ATG media lab