362 transformer to the design. The addition of the rotary transformer added a significant amount of weight,  approximately 2.0 kg,  power,  and some minor complexity to the control system electronics design but the  trade decision was made that the added mass, power, and complexity was worth the risk mitigation that was gained by making this aspect of the design more robust.   Table 1. SMA Design Driving Requirements 

 All the other changes to the SMA design were primarily within the SRA. For instance, the SRA for BAPTA had 137 rings, whereas, for GMI the SRA needed to have 124 rings for all the GMI signals. The BAPTA SRA manufacturer acquired and combined with another supplier. Extensive time and effort was spent to recover the BAPTA SRA heritage design. That proved to be a much tougher task, as it turned out, than anyone anticipated. The basic design and production knowledge was essentially still there, but a few of the critical process details of exactly how to produce the product as desired, why it was important, and what the impacts were was lost, and had to be re-created, to meet the specification requirements of the design.   The most obvious challenge in the early SMA development was trading either adapting the drive to meet the GMI instrument interfaces and requirements, or alternatively, adapting the GMI interface (or derived requirements) so that the SMA design configuration would, or could be made to meet them without adversely affecting the functional and performance heritage of the drive or principle critical elements. One of the biggest of these challenges was converging on an instrument interface and load path for the GMI instrument that would be consistent with the load capacity and stiffness of the SMA bearings and drive configuration.   99.721% reliability 0.13 MS SMA lube0.38 MS SRA lubeDesign Life38 months on-orbit op + 12 months  I&T + 2.4 months op storage (2 yr @  10%); total life reqmt 52.4 months20.29 kgMass 20.4 kg maximum 0.222 MS Torque Margin1.5x on known's, 2x on variables32 + 0.3% RPM 0 – 33 RPMRotation Rate /ControlRate shall be 32 + / - 0.3% RPM  Range shall be 0 – 33 RPM 10 to 15C OpOperating and Non Operating  Temperatures On-orbit Op: 0 to +50CSurvival: -35 to +55C60.8 Hz > 7.6 Hz > 7.8 HzStiffness First mode > 50 Hz (in GMI assy) Deployed First Mode > 6 Hz De-spin torsion > 7.6 Hz49.6 arcsec (RSS) 11.5 arcsec (RSS)Spin axis Align to base shall be < 75 arcsec  Wobble shall be < 30 arcsec 3 sigma  44 arcsec (32 tachpulses / rev)Position Uncertainty Tach pulses/rate control position  accuracy < 60 arcsecPredicted  PerformanceRequirement 99.721% reliability 0.13 MS SMA lube0.38 MS SRA lubeDesign Life38 months on-orbit op + 12 months  I&T + 2.4 months op storage (2 yr @  10%); total life reqmt 52.4 months20.29 kgMass 20.4 kg maximum 0.222 MS Torque Margin1.5x on known's, 2x on variables32 + 0.3% RPM 0 – 33 RPMRotation Rate /ControlRate shall be 32 + / - 0.3% RPM  Range shall be 0 – 33 RPM 10 to 15C OpOperating and Non Operating  Temperatures On-orbit Op: 0 to +50CSurvival: -35 to +55C60.8 Hz > 7.6 Hz > 7.8 HzStiffness First mode > 50 Hz (in GMI assy) Deployed First Mode > 6 Hz De-spin torsion > 7.6 Hz49.6 arcsec (RSS) 11.5 arcsec (RSS)Spin axis Align to base shall be < 75 arcsec  Wobble shall be < 30 arcsec 3 sigma  44 arcsec (32 tachpulses / rev)Position Uncertainty Tach pulses/rate control position  accuracy < 60 arcsecPredicted  PerformanceRequirement