An ultra stable optical bench for the magnetic survey satellite

The Magsat optical bench has been designed and built to hold the alignment of five optical elements to deflections of 1-2 arcsec during orbital operation. The bench has been designed to withstand alignment changes during the launch and prestabilization phases of the mission. Severe weight constraints, in conjunction with the thermal and structural requirements, led to the choice of graphite-fiber-reinforced epoxy egg crate core and face sheets for the bench construction. Active temperature control was necessary to meet thermal deflection objectives, and novel kinematic mountings were required to prevent spacecraft bending from deflecting the bench.