Some Observations with JWST’s MIRI Instrument Paused

Some Observations with JWST’s MIRI Instrument Paused

NASA’s James Webb Space Telescope continues to produce astounding images, but NASA reported today that a problem has developed with one of the instruments, MIRI. An anomaly review board has been convened and observations using one mode of MIRI’s operations are paused, but the rest of the telescope is OK.

JWST has four instruments. MIRI, the Mid-InfraRed Instrument, was built by NASA and ESA with the European Consortium. The Space Telescope Science Institute operates the telescope and is releasing dazzling images taken by MIRI itself or combined with data from the other instruments.

The Tarantula Nebula as imaged by the MIRI instrument. Credits: NASA, ESA, CSA, STScI, Webb ERO Production Team

MIRI can study the universe in wavelengths between 5 and 27 microns in four different modes: low-resolution spectroscopy, medium-resolution spectroscopy, and two types of coronagraphic imaging.

NASA said today that on August 24 a “grating wheel” that supports the medium-resolution spectroscopy “exhibited what appears to be increased friction during setup for a science observation.”

Heidi Hammel, an interdisciplinary scientist on the JWST project, described it as “sticky.”

An anomaly review board convened on September 6 and NASA has paused scheduling observations in this mode until they decide what to do next. The other MIRI modes are fine as are the other three instruments — the Near Infrared Camera (NIRCam), the Near Infrared Spectrometer (NIRSpec), and the Fine Guidance Sensor/Near Infrared Imager and Slitless Spectrograph (FGS/NIRISS).

In fact, NASA just released images and spectra taken of Mars by NIRCam on September 5. Although JWST is designed to look deep into the universe and find the faintest infrared (heat) signatures, it also can be used to study objects as close as Mars though it takes a bit of doing. The infrared light from Mars is so intense it can overpower JWST’s sensors, so scientists have to use very short exposures and measure only some of the light that’s detected.

Webb’s first images of Mars, captured by its NIRCam instrument Sept. 5, 2022 [Guaranteed Time Observation Program 1415]. Left: Reference map of the observed hemisphere of Mars from NASA and the Mars Orbiter Laser Altimeter (MOLA). Top right: NIRCam image showing 2.1-micron (F212 filter) reflected sunlight, revealing surface features such as craters and dust layers. Bottom right: Simultaneous NIRCam image showing ~4.3-micron (F430M filter) emitted light that reveals temperature differences with latitude and time of day, as well as darkening of the Hellas Basin caused by atmospheric effects. The bright yellow area is just at the saturation limit of the detector. Credit: NASA, ESA, CSA, STScI, Mars JWST/GTO team
Greg Robinson, NASA JWST Program Director (retired). Photo credit: NASA

JWST is a cooperative program among NASA, the European Space Agency, and the Canadian Space Agency. ESA provided NIRSpec, CSA provided the FGS/NIRISS, and the University of Arizona provided NIRCam. The spacecraft that houses all of those instruments was provided by NASA (Northrop Grumman was the prime contractor). ESA was responsible for the December 25, 2021 launch on an Ariane 5 rocket that sent JWST to its observing location a million miles from Earth at the Sun-Earth Lagrange Point-2 (SEL-2).

JWST was years late and billions over budget. NASA’s Greg Robinson served as Program Director for the last three years of the development program and is winning kudos for getting it over the finish line. Robinson retired from NASA in July after more than 30 years of federal service soon after JWST was declared operational. Today he was honored with the prestigious 2022 Federal Employee of the Year medal by the Partnership for Public Service at a gala at the John F. Kennedy Center for the Performing Arts. He also has been named one of the TIME 100 Most Influential People of 2022 and to the EBONY 2022 Power 100 list.

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