For gimbal/boom dynamic interaction, the gimbal was in strumented with force gages, and the forcing  function was used to derive the jitter error measurements. The item tested was an engineering test unit,  flight-like in all structural respects.  For the gimbal tracking error, the budgeted amount of 0.08 degree was calculated by summing estimates  for the following for each axis:  harmonic drive wind -up, gear error, step late ncy, and wobble of the  actuator output. The results were added vectorially (Root-Sum Squared). For the measured value of  0.041 degree, the rotational error and the wobble were measured for each axis and added together  vectorially. Due to 1-g effects, this error is greater than the value will be on orbit.  Harnessing and Multi Layer Insulation  Some more general lessons learned deal with leaving more space for harnessing and multi-layer  insulation (MLI) and addressing these details earlier in the design effort. Since the gimbal is deployed away from the spacecraft body, it is exposed to  the worst radiation environment and temperature  extremes on the entire spacecraft, except perhaps for the instrument complement. Protecting against this  onslaught required elaborate measures that were frequently at odds with the smooth operation of a high-precision pointing mechanism.    The volumetric demands fo r harnessing were especially great. Even though the Tefzel ®-insulated wiring is  resistant to radiation, the SDO system designers implemented a policy of over-wrapping exposed  actuator wires with Kapton, Lead and Aluminum tape.  Becau se of the reliability requirements for a 5-year  mission at geo-synchronous orbit, the tape layers plus the 36 wires from a single actuator formed a bundle that was approximately 15.9 mm (5/8 inch) in diameter. After wrapping, the metallic layers were  each electrically bonded to grou nd with silver-filled epoxy.   MLI over the entire spacecraft has an electrically conductive germanium black Kapton ® (GBK) outer layer.   MLI is usually a challenge to bend and position in small pieces and tight quarters. The extra layers  brought additional concerns as the mechanism and thermal goals conflicted. The gimbal required ten separate MLI pieces in order to protect its  various convoluted surface features, as well as allow for  access to the various parts. Some MLI pieces were only 15 cm (6 in) on a side. The bends and seams,  such as between moving parts, are potential heat leaks that could expose the actuators to dangerous  extremes of temperature. In addition, GBK is sensitive to even light abrasion such as normal hand  pressure from an accidental brush against its surface. All these factors contributed to a tough challenge of constructing accurate, intricate pieces of MLI, tightly positioned, and allowing free relative motion between  close-tolerance parts.    Conclusion  The first flight gimbal, shown in Figure 8, has been tested and delivered to the spacecraft. The second  gimbal will be replaced by a spare after being subjected to damaging temperatures during the postthermal vacuum bake-out. Integration and testing of the re-built gimbal is scheduled to be complete in  March 2008. Launch is scheduled for late 2008. Acknowledgements  Richard Barclay, Carlos Lugo – gimbal electronics  Steven Wood – mechanical assembly  Richard Marriott – materials Michael Dube – ECRA noise investigation  Javier Lecha, Joe Schepis – HGAS  Jason Hair – HGAS deployment  Ken Hersey – RF  SpaceDev/Starsys – actuators and ECRAs Kevlin Corporation – RF rotary joints  424