Engineers have begun the final stage of Webb's major structural deployments: the unfolding of its two primary mirror wings. These side panels, which were folded back for launch, each hold three of the observatory's 18 hexagonal, gold-coated mirror segments.

The team is beginning today with the mirror wing on the port (left) side of the observatory. Engineers must first release mechanisms that held the wing in place for launch, in order to allow the wing to deploy. The panel then rotates into position, a motor-driven process that takes about five minutes. Once the wing is extended, engineers begin a meticulous, two-hour process to securely latch it into place.

The deployment of the second primary mirror wing, planned for tomorrow, will follow the same process.