The
SPACE testbed is designed to emulate a Cassegrain telescope of 2.4-meter
focal length with performance comparable to an actual space-borne
system. The system's top-level requirements figure maintenance of
the primary mirror to within 1 micron RMS distortion with respect
to a nominal shape of the primary mirror, pointing accuracy of 2 arc
seconds, a high level of disturbance rejection (100:1), and attenuation
of vibration due to gravity, thermal and seismic effects, and control
structure interaction. The primary mirror is composed of a ring of
six actively controlled hexagonal panels arranged around a central
panel. The central panel is fixed and serves as a point of reference
to the moving panels. The testbed is a control-oriented experimental
system and due to the difficulty and added expense of actual optical
quality segments made from glass, the panels are made of aluminum
honeycomb plates. The required paraboloid surface is thus maintained
by positioning the flat panels as tangents to the surface.
