1. MPSRAlignments - 1 UCB, Oct 26, 2006 THEMIS PROBE MISSION PRE-SHIP REVIEW Alignments Paul Turin LME University of California - Berkeley

2. MPSRAlignments - 2 UCB, Oct 26, 2006 Alignment Overview Three alignments tasks: –Post-environmental testing alignment verifications for MSSS and thrusters, comparing to SAI measurements –Alignment measurements of magnetometer booms and generation of transformation matrices for locating mag mounts to the probe geometric axes –Check probe alignment on Miller table for spin balance Measurements were performed by Bob Connors of LBNL using LBNL FARO Gold CMM arm (0.003” accuracy) All measurements and comparisons are complete

3. MPSRAlignments - 3 UCB, Oct 26, 2006 SAI Supplied Alignment Data Contains: Probe Coordinate System(C1) Probe Ground Alignment Coordinate System(C4) AXB Axis MSSS Fiducial Tree Thruster axes All UCB measurements recorded in same file.sat file output from FARO arm:

4. MPSRAlignments - 4 UCB, Oct 26, 2006 Alignment Verification for MSSS, Thrusters Used FARO arm used to pick up probe C4 coordinate system tooling balls Measured thrusters and MSSS using SAI fixtures Calculated angles between Probe axes and thrusters Compared MSSS SAI and SSL Goals: –MSSS 1° –Thrusters 0.5°

5. MPSRAlignments - 5 UCB, Oct 26, 2006 Sun Sensor Alignment Check UCB fiducial triad normal vectors compared to SAI. The same within the accuracy of the FARO arm (0.06 ° ) and much better than the goal of 1 ° :

6. MPSRAlignments - 6 UCB, Oct 26, 2006 Thruster Alignment Check Both SAI and SSL measurements exceed requirement of.5° (yellow). Exceedances deemed acceptable by SAI (SAI-TM-3030 & -3054) Exceedances accepted based on fuel consumption analysis that shows still less than all thrusters off by.5° SSL FARO measurements not very reliable due to req’d contact force and flexibility of thruster Holding 2-part tool in place elastically flexes thruster Force of Faro contact caused deflection

7. MPSRAlignments - 7 UCB, Oct 26, 2006 Alignment Measurements for Magnetometers No MRD alignment requirement, desire is: Aligned within a few deg, knowledge within 1° Measurements: Determine end-to-end magnetometer mount angular offsets from geometric axes, and total uncertainty SAI Probe C4 Coordinate System + Final C4 to Fiducial Alignment Measurements + UCB Mag to Fiducial Alignment Offsets Total Alignment Offsets + Final Alignment uncertainty SAI Probe C4 coordinate System uncertainty + UCB Mag Mount to Fiducial uncertainty Total Uncertainty

8. MPSRAlignments - 8 UCB, Oct 26, 2006 Magnetometer Theoretical Angles

9. MPSRAlignments - 9 UCB, Oct 26, 2006 C4 to Mag Boom Fiducial Measurements Fiducial on stowed boom is measured from probe C4 coordinate system This data used to build solid models of actual fiducial w/r/t C4

10. MPSRAlignments - 10 UCB, Oct 26, 2006 Mag-to-Boom Alignment Data Mag Mount to Fiducial Alignment Offsets: This data used to build solid models of actual mag positions w/r/t fiducial:

11. MPSRAlignments - 11 UCB, Oct 26, 2006 Solid Models Generated from Measurement Data Mag-to-Boom Alignment Model Mag-to-Boom Theoretical Model Probe-to-Mag boom Fiducial Model

12. MPSRAlignments - 12 UCB, Oct 26, 2006 Models Combined to Create End-to End Model

13. MPSRAlignments - 13 UCB, Oct 26, 2006 Angles and Worst-Case offsets

14. MPSRAlignments - 14 UCB, Oct 26, 2006 Mag Mount CS Unit Vectors in PCS

15. MPSRAlignments - 15 UCB, Oct 26, 2006 Mag Mount CS Unit Vectors in PCS cont.

16. MPSRAlignments - 16 UCB, Oct 26, 2006 Transformation matrices Actual mag mount CS unit vector direction cosines in PCS become transformation matrix for getting from sensor mount into probe coordinates. Combined with G2S and M2U transformations gives end-to-end solution.

17. MPSRAlignments - 17 UCB, Oct 26, 2006 FGM Boom Total Measurement Uncertainty Mag Boom Measurement Errors Probe Measurement Errors Probe Geometric Axis to Magnetic Axes Uncertainty

18. MPSRAlignments - 18 UCB, Oct 26, 2006 Effect of worst-case mag boom misalignments on spin balance and CG Because all of the mag to probe measurements are angular, the actual mag offsets (and hence their effects of spin bal) are unknown. Effect was checked by assuming location of angular error is at the shoulder, which leads to worst-case translation. Resulting tilt and CG shift was calculated and shown to be negligible.

19. MPSRAlignments - 19 UCB, Oct 26, 2006 Spin Balance Alignment Probe position was checked on Miller table to verify that the probe geometric axis was coincident with the table spin axis. Uncertainty in measurement is 0.013° and.005”.