Webb space telescope unfolds secondary mirror in latest milestone: "Another banner day"

In another major milestone for the James Webb Space Telescope, a motor-driven tripod unfolded as planned Wednesday, moving a 2.4-foot-wide secondary mirror into position to reflect collected starlight back down to the instruments that will study it.

While the deployment of the telescope's sunshield Monday and Tuesday marked the most technically challenging hurdle for Webb's initial activation, getting the secondary mirror in position was equally critical to the success of the $10 billion mission.

To fit inside the nose cone of its European Space Agency-supplied Ariane 5 rocket, the secondary mirror assembly, made up of three 25-foot-long struts, had to be folded up. On Wednesday, commands were sent to unlatch the hinged legs of the tripod so a motor could drive them open.