a beryllium copper diaphragm flexure to maintain ball-race contact and prevent skidding. The 3rdaxis bearings were sized to handle worst case loads with positive margins. The support brackets were fabricated from Titanium 6AL-4V for excellent strength and stiffness characteristics plus low CTE to  prevent damaging the bearings during cold survival temperatures. The bearings were lubricated with Braycote 601EFVB. Labyrinth seals and barrier film are used to prevent lubrication migration. Gimbal The 2-axis gimbal is mounted to the top of the mast with the azimuth axis actuator located mostly inside  the vertical shaft of the mast as shown in Figure 11. The optical bench is mounted to the elevation axis actuator via a gimbal to bench mounting bracket. The gimbal harness is routed through the bottom of the  mast and out of the 3 rdaxis single radial bearing bore. Analysis The major components of the TPS were designed and analyzed to meet the requirements of the  NPOESS mission. ANSYS Workbench was used to predict structural and thermal stresses along with modes during the launch and deployed configurations. The predicted 1 stmode is 67 Hz in the stowed  configuration and 8.1 Hz in the deployed configuration. Individual piece parts and small sub-assemblies that are in the load path were analyzed in ANSYS and the geometry was modified as required to result in positive margins of safety for worst case load configurations. All moving parts including the actuator,  bearings, gears and ball screw were analyzed and sized to withstand lifetime cycles. The mean Hertzcontact stress was calculated for all bearings in the system to verify that they met the requirement of <400 ksi (<2760 MPa). All had healthy margins of safety. Testing Life Test In early 2012, the TPS successfully completed a life test of 100 stow-deploy cycles. A mass model that  matched the mass and Center of Gravity (CG) of the populated optical bench was attached to the top of  the mast for this test. Fifteen of the cycles occurred in the thermal vacuum chamber with 5 cycles at ambient temperature, 5 cycles at -20C, and 5 cycles at +40C. The remaining 85 cycles took place atambient temperature and pressure in a cleanroom. Each cycle required just over 60 minutes to complete. Figure 12 shows the TPS about to enter the thermal vacuum chamber. Figure 13 shows life test data for  cycles 34-40. During the 100 cycle life test, the actuator operated nearly continuously for a total of 100 hours. A  thermocouple was bonded to the body of the motor and the temperature was continuously monitored throughout the entire test. An automatic shut off set at +150C was built into the control software to avoid damaging the actuator. The actuator temperature limits specified by the manufacturer are -80C to +225C. The specified temperature limits for Braycote 601EFVB are -80C to +204C. The temperature gradient  between the external surface of the actuator and the thermocouple along with a healthy safety factor were the rationale behind the +150C shut off. The automatic shut off was never triggered during the life test. The maximum temperature that the thermocouple measured was +134C during the hot (+40C) test in the  thermal vacuum chamber. 445