On what date did JWST enter service?

The James Webb Space Telescope entered service on 12 July 2022. That date marked the public release of its first full-color images and spectra and the official beginning of its science mission.

JWST launched on 25 December 2021, but launch did not mean it was immediately operational. During the following six months, engineers unfolded its sunshield and mirror, aligned the 18 mirror segments, cooled the observatory, calibrated its instruments, and checked its scientific operating modes.

The date can be confused with 11 July 2022, when U.S. President Joe Biden unveiled Webb’s first image, a deep field of galaxy cluster SMACS 0723. The full set of initial images and spectra was released the next day, on 12 July.

Those first observations demonstrated Webb’s ability to study distant galaxies, star-forming regions, dying stars, and exoplanet atmospheres. The release opened routine observing to astronomers worldwide.