A cosmic ray struck the James Webb Space Telescope (JWST) and frazzled one of its instruments, according to NASA and the Canadian Space Agency (CSA).

Canada’s contribution to JWST, the Near Infrared Imager and Slitless Spectrograph (NIRISS), experienced a puzzling anomaly on January 15, when it suffered a communications delay within the instrument. This then caused NIRISS’ flight software to time out. After a thorough review, a reboot, and a test observation, teams from both space agencies are breathing a sigh of relief.

NIRISS is one-fourth the scientific power of JWST. The instrument absorbs light beyond visible red in the electromagnetic spectrum. Sometimes it takes pictures. Other times, it collects data that tell scientists the composition of dust and gas far away in space. In this last year, NIRISS has been used to study the atmospheres of potentially-habitable alien worlds.

For NIRISS and the other three instruments onboard JWST to operate at their prime, NASA, CSA, and the European Space Agency (ESA) elected to fly the telescope to a frigid place about a million miles away from Earth. Here, without the heat radiation of our planet to distract the spacecraft, JWST can sense the subtlest clues from incredible distances.

But this perch also leaves it vulnerable to cosmic rays. These slingshots of high-energy are an occupational hazard, according to the NASA blog post on Tuesday that provided the latest NIRISS update. “Encountering cosmic rays is a normal and expected part of operating any spacecraft,” according to the blog.

“Following a full investigation by NASA and Canadian Space Agency (CSA) teams, the cause was determined to likely be a galactic cosmic ray, a form of high-energy radiation from outside our Solar System that can sometimes disrupt electrical systems,” they added.

JWST engineers decided to reboot the instrument, after determining that was a plausible way to bring NIRISS back online. This seemed to resolve the communications delay. But they did a check to make sure, and got positive results on Monday.

“After completing the reboot, NIRISS telemetry data demonstrated normal timing, and to fully confirm, the team scheduled a test observation. On Jan. 28, the Webb team sent commands to the instrument to perform the observation, and the results confirmed on January 30 [that] NIRISS is back to full scientific operations,” according to the blog.

The telescope released its first batch of science data in July 2022, thrilling the public around the world with never-before-seen views of the Universe. Dan Coe, a JWST Instrument Scientist who works on its Near-Infrared Camera (NIRCam), recently told Inverse that the latest call for research proposals may have brought in a record-breaking number of submissions.