NASA’s James Webb Space Telescope is another step closer to aligning the observatory’s primary mirror, thanks to its near-infrared camera (NIRCam) instrument. In a test to see if NIRCam is ready to collect light from celestial objects by identifying starlight from the same star in each of the 18 primary mirror segments, the result is an emphatic yes. It produced an image mosaic of 18 randomly organized dots of starlight, according to NASA, which means Webb’s unaligned mirror segments are all reflecting light from the same star back at its secondary mirror and right into NIRCam’s detectors.
The image capturing process began on February 2, 2022 and lasted nearly 25 hours. By repointing Webb to 156 different positions around the star’s predicted location, NIRCam’s detectors generated 1560 images, which equates to 54 Gbytes of raw data.
Stitching the images together creates a single, large mosaic that captures the signature of each primary mirror segment within one frame. Optics experts and engineers can use this data to align the entire telescope and focus it—until the 18 images become a single star—so it can begin providing views of the universe this summer.
