Assembling the primary mirror support system. The mirror is supported by six primary trusses, seen here attached to the hub, and six secondary trusses. Here, the first of the secondary trusses is being positioned. The mirror shell is supported at 19 points, on the black aluminum disks, three of which are shown in the picture. Close up of the central hub and radial arms.
Turnbuckle screws allow adjustment of the lengths.
Attachment point of a primary truss to the hub. The air bearing can be seen below. One of the mirror axial supports. A fine-pitched screw provides height adjustment. Self-aligning bearings and a pivot allow the support to adapt to differences in thermal expansion of the truss and mirror shell.