NASA's James Webb Space Telescope, the largest and most powerful telescope ever launched, has demonstrated exceptional stability in its mirror alignment, requiring fewer corrections than anticipated since its launch. The telescope's mirror consists of 18 segments that must be aligned with precision to function as a single unit, a process that took nearly three months post-launch.
Dr. Marcio B. Meléndez, principal astronomical optics scientist for Webb, explained that maintaining this alignment is crucial due to factors like temperature variations. The wavefront sensing team at the Space Telescope Science Institute monitors the telescope's mirrors regularly, utilizing specialized optical sensing equipment within the Near Infrared Camera (NIRCam) to assess alignment through a technique called phase retrieval.
Observations are conducted every other day, and the team performs a quarterly 'selfie' of the mirror segments to evaluate their health. The telescope has achieved a wavefront error of only 65 nanometers, significantly better than the design requirement of 150 nanometers. This precision allows Webb to capture more sensitive images of faint celestial objects.
Since commencing scientific operations, the team has executed over 25 corrective moves to maintain alignment, ensuring that the telescope's optical performance remains optimal. The stability observed in Webb's alignment is promising for future missions, particularly for NASA's upcoming Habitable Worlds Observatory, which aims to search for life on Earth-sized exoplanets.