James Webb Space Telescope resumes science operations after glitch

MIRI mechanism issue
On August 24, Webb engineers discovered that a grating wheel mechanism which supports the telescope’s “medium-resolution spectroscopy” (MRS) mode was showing signs of increased friction. The wheel is only used for one of the telescope’s four modes, which includes imaging, low-resolution spectroscopy, coronagraphic imaging and MRS.
After preliminary health checks and investigations, Webb teams convened an anomaly review board on September 6 to arrive at the best path forward. In the meanwhile, engineers paused observations using the MRS mode while continuing to take observations with the other three modes.
Diagnosis for Webb
After weeks of in-depth investigation that included scrutinising the design of the mechanism as well as data from the telescope, the anomaly review board concluded that the issue was most likely caused increased contact forces between the wheel’s components that arise under certain conditions.
Unlike Hubble, which orbits at around 535 kilometres away from the surface of our planet, Webb is situated at the second Lagrange point (L2), which is about 1.5 million kilometres away from our planet. Due to this, Webb was designed to function in the absence of servicing capabilities, meaning that there is no way to visit the telescope and fix the issue.

So, based on the recommendations of the anomaly review board,Webb teams have devised a new method to use the mechanism despite the issue. These new operational parameters were executed on November 2, 2022, and were found to be successful.
The telescope can now return to making MRS science observations with these new operational parameters. “MIRI is resuming MRS science observations, including taking advantage of a unique opportunity to observe Saturn’s polar regions. The JWST team will schedule additional MRS science observations, initially at a highly-orchestrated cadence with additional trending measurements to monitor the new operational regime of the mechanism to prepare MIRI’s MRS mode for a return to full science scheduling,” said the Space Telescope Science Institue, in a press statement.
MRS mode
In its MRS mode, the Webb telescope observes spectroscopic data of life reflected dant cosmic objects to help scients look for the presence of certain. According to NASA, this ability would be useful for detecting molecules in planet-forming “protoplanetary” disks. The telescope continued to function and display its abilities in the absence of this mode, as can be seen with the recently released “haunting portrait” of the Pillars of creation.