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.

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.