Thomas A. Sebring
The vertices of the base wedge's equilateral triangle, which can be seen on its front face, are the locations of special
"kinematic" mounts for the primary mirror truss, which constrain the ways the mirror truss can move. Because of
these special mounts, deformation of the base wedge can change the pointing of the primary mirror but cannot
induce any bending in the truss; truss bending would distort the shape of the primary surface, which would affect
the telescope's optical performance.