NASA has stopped using one mode on its James Webb Space Telescope (JWST), Mid-Infrared Instrument, (MIRI), due to “increased friction” during the setup phase before new observations.
The issue was first noticed on August 24 and affects the MIRI camera, which has four observation modes. NASA described an “increased friction” in a mechanism supporting one of these modes (called medium-resolution spectrum, or MRS) during the setup process for science observations.
“This mechanism is a grating wheel that allows scientists to select between short, medium, and longer wavelengths when making observations using the MRS mode,” NASA explains. “Following preliminary health checks and investigations into the issue, an anomaly review board was convened Sept. 6 to assess the best path forward.”
The MIRI camera is one of four main observation instruments on the JWST; the other more well-known is the Near Infrared Camera (NIRCam). MIRI is perhaps most famous for the fact that it is the super-cooled camera and needed to be brought to a temperature of minus 447 degrees Fahrenheit in order to operate correctly, which it did through a combination of a sun shield — which is the size of a tennis court — and an electrically powered cryocooler.
MIRI was used to take some of the best photos the JWST ever took, such as the Southern Ring Nebula and the Cartwheel Galaxy. It is often used in combination with NIRCam to produce a multi-spectral final image.
The Webb team has paused use of this particular observation mode while they continue to analyze its behavior. The space agency says that the team is currently developing strategies to resume the use of the MRS for observations as soon as possible, but did not provide a specific timeline.
Outside of this particular mode, NASA says that the JWST is in otherwise good health and the other three MIRI observation modes — imaging, low-resolution spectroscopy, and coronagraphy — are operating normally and remain available for science observations.
NASA is unable to fly an entire team into space in order to fix the JWST, unlike what happened with the Hubble Space Telescope. Hubble orbits Earth which makes it possible to send a spacecraft to. However, the JWST lies about one million miles away. Because it is so far from Earth, the JWST doesn’t orbit Earth but orbits instead the Sun. As such, physical repairs aren’t an option. The Webb team will have to solve this particular problem remotely.
This is the second issue that the JWST has experienced since it launched, the other was a minor impact by a meteorite which did damage one of the primary mirror segments, but was not a cause for alarm.