James Webb Space Telescope resumes science operations after glitch

Earlier this year, NASA scientists ran into a technical glitch with the James Webb Space Telescope's Mid-Infrared Instrument (MIRI) instrument.

After convening an expert panel and diagnosing the issue, NASA teams have devised new operational procedures to allow the telescope to continue science observations despite the glitch.

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.

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 by increased contact forces between the wheel's components that arise under certain conditions.

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.