MISSION PRE-ENVIRONMENTAL REVIEW THEMIS MISSION PRE-ENVIRONMENTAL REVIEW Alignments Paul Turin LME University of California - Berkeley

Alignment Overview There are three alignments tasks: Alignment Verifications for MSSS and Thrusters, comparing to SAI measurements Alignment Measurements of Magnetometers to determine offsets from probe geometric Z axis and clocking in XY plane Align probes on Miller table for spin balance Measurements will be performed by Bob Connors of LBNL using LBNL FARO Gold CMM arm (0.003” accuracy) Currently working on measurements for F2 Learn how to do it, work out the bugs in process Verify no changes to probe alignments do to environments F1, F3-5 alignments will be verified and measured during “round-robin” activities at JPL (post vibe)

SAI Supplied Alignment Data .sat file output from FARO arm: Contains: Primary coord sys (C1) Secondary coord sys (C4) AXB Axis MSSS Fiducial Tree Thruster axes Files for all five probes delivered to UCB

Alignment Verification for MSSS, Thrusters Use FARO arm to pick up probe C4 coordinate system Measure thrusters and MSSS using fixtures Calculate angles between SAI and UCB data Determine if still within tolerances (SAI-PLAN-643) Requirements: MSSS 1deg Thrusters 0.5 deg

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

Magnetometer Theoretical Angles

Mag Boom Fiducial Angles between mag mount and fiducial are measured on deployed boom, fiducial is measured from probe C4 coordinate system

Mag-to-Boom Alignment Data Mag Mount to Fiducial Alignment Offsets: Deployment Repeatability:

Mag Boom Total Measurement Error Mag Boom Measurement Errors Probe Measurement Errors Probe Geometric Axis to Magnetic Axes Knowledge

Spin Balance Alignment on Miller Table Determine alignment of probe geometric Z axis to Miller table spin axis Determine alignment of probe XY clocking to Miller table azimuth zero Probe is located during installation to the table by boss that aligns AXB tube to table spin axis AXB tube is not guaranteed to be perpendicular to sep system bottom C4 tooling balls are used to determine AXB axis tilt and probe clocking on table