Skip to main content

One of James Webb’s 17 instrument modes isn’t working

While the James Webb Space Telescope has been both a huge popular success and a highly effective research tool so far, not everything is perfect with the new observatory. This week, NASA announced that one of Webb’s 17 observing modes is not functioning due to a hardware issue that is currently under review.

Webb has four instruments, all of which operate in the infrared portion of the spectrum. Three of the instruments — NIRCam, NIRSpec, and NIRISS — operate in the near-infrared and are working as intended, but there is an issue with the fourth instrument, MIRI, which operates in the mid-infrared.

Recommended Videos

Each of the instruments can operate in different modes, such as switching between imaging and spectroscopy. There are seventeen of these modes in total, and it is one of MIRI’s modes that is not functioning.

While Webb’s other instruments are useful for cosmology research such as looking back at the earliest galaxies, MIRI, or the Mid-Infrared Instrument, is particularly useful for studying how stars and planets form. Its four modes include an imaging mode for taking pictures of dust and gas throughout galaxies, like a recent image taken of the galaxy Messier 74, and a coronagraphic mode in which light from bright stars can be blocked out to observe the exoplanets which orbit them. It also has two spectroscopy modes, and it is one of these which is not working.

“On August 24, a mechanism that supports one of these modes, known as medium-resolution spectroscopy (MRS), exhibited what appears to be increased friction during setup for a science observation,” NASA wrote in an update. “This mechanism is a grating wheel that allows scientists to select between short, medium, and longer wavelengths when making observations using the MRS mode.”

For now, scientists will not be using the MIRI medium-resolution spectroscopy mode while the issue is investigated. NASA says that an anomaly review board will be deciding on how to move forward and that teams are working on ways that the mode could be brought back into a working state. MIRI’s other three modes are still working fine, so the issue is contained to just the one mode.

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
One galaxy, two views: see a comparison of images from Hubble and Webb
The peculiar galaxy NGC 3256 takes centre stage in this image from the NASA/ESA Hubble Space Telescope. This distorted galaxy is the wreckage of a head-on collision between two spiral galaxies which likely occurred 500 million years ago, and it is studded with clumps of young stars which were formed as gas and dust from the two galaxies collided.

It might not seem obvious why astronomers need multiple different powerful space telescopes. Surely a more powerful telescope is better than a less powerful one? So why are there multiple different telescopes in orbit, either around Earth or around the sun?

The answer is to do with two main factors. One is the telescope's field of view, meaning how much of the sky it looks at. Some telescopes are useful for looking at large areas of the sky in less detail, working as survey telescopes to identify objects for further research or to look at the universe on a large scale -- like the recently launched Euclid mission. While others, like the Hubble Space Telescope, look at small areas of the sky in great detail, which is useful for studying particular objects.

Read more
James Webb spots the most distant active supermassive black hole ever discovered
Crop of Webb's CEERS Survey image.

As well as observing specific objects like distant galaxies and planets here in our solar system, the James Webb Space Telescope is also being used to perform wide-scale surveys of parts of the sky. These surveys observe large chunks of the sky to identify important targets like very distant, very early galaxies, as well as observe intriguing objects like black holes. And one such survey has recently identified the most distant active supermassive black hole seen so far.

While a typical black hole might have a mass up to around 10 times that of the sun, supermassive black holes are much more massive, with a mass that can be millions or even billions of times the mass of the sun. These monsters are found at the heart of galaxies and are thought to play important roles in the formation and merging of galaxies.

Read more
Saturn as you’ve never seen it before, captured by Webb telescope
Saturn captured by the James Webb Space Telescope

NASA has shared a gorgeous image of Saturn captured recently by the James Webb Space Telescope (JWST).

Webb’s first near-infrared observations of the second largest planet in our solar system also show several of Saturn’s moons: Dione, Enceladus, and Tethys.

Read more