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

2. 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)

3. 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

4. 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

5. 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

6. Magnetometer Theoretical Angles

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

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

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

10. 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