THEMIS INSTRUMENT SUITE FM4/FM5 PRE-SHIP REVIEW MAGNETOMETER BOOMS Paul Turin Themis Lead ME University of California - Berkeley

Outline Summary of Current Mag Boom Status FM4/5 Configuration End Item Data Package ToC Requirements Fulfillment of Requirements PFR Status RFAs, Closeouts, Rework, etc. Appendices (testing info)

Mag Boom Status Requirements and Design: Assembly, and Test: No change to (official) Requirements since MCDR Changes to Boom design due to other considerations: Tilt upwards 5 deg (FGM)10 deg (SCM) to reduce S/A shadowing Required taller frangibolt towers, inclined pivots Raise boom height above deck to clear higher solar array Required raising shoulder bases on taller feet Several more changes needed to fix problems caused by 1st two changes: Strengthen SCM Frangibolt tower Strengthen SCM Shoulder Feet Flexures Replace FR-4 thermal isolators with steel blocks Redesign shaft retention set screws Assembly, and Test: 5 flight and 1 flight spare boom sets have completed functional and environmental testing and have been delivered to Suite I&T. Deployments during Suite TV complete.

Configuration Mag Boom Configuration by Serial Number: FM4 suite contains FM4 FGB and FM4 SCB FM5 suite contains FM5 FGB and FM5 SCB

EIDP

Mag Boom Requirements UPDATE! Ask Ellen about my mods, see if has new version

Satisfaction of Requirements Test Proof test of graphite tubes Ambient, 0 rpm deployment test Sine, Random Vibration test Thermal vacuum test (cycling + Hot and Cold 1st motion deployments) 15 rpm equivalent drop test Repeatability test Torque margin test Mag alignment verification Length Measurement Satisfies Requirement GEVS IN.BOOM_4 IN_BOOM_2,4 IN.BOOM_1 Science IN_BOOM_9,10 All test complete, all booms passed, all results in family (except FM6, still acceptable)

PFR Status PFR Status Title Resolution PFR-025 CLOSED Cracked feet in SCB frangibolt tower Replaced DAD Tower PFR-027 Cracked Base Bracket in SCB Redesigned tower, used steel washers PFR-041 Spring spool in SCB base hinge loosened by vibration. Tightened Spools with new tool to higher torque PFR-043 Damaged threads in FGB frangibolt ring. Repaired thread with helicoil. Affects FM6 spare only PFR-044 Friction increase in hinge mechanism after vibe Set screw backing out and binding – larger screw used and staked PFR-053 Increased base hinge friction post vib at qual levels Bronze on Al galling -- SS shim added for bronze bushing to ride on PFR-058 SCB connector wire damage ETU cable too short – Flight long enough PFR-073 Length Discrepancy between SCM Flight Harnesses All cut to same length PFR-077 FM1 FGB Fail to deploy in Cold Vacuum Test Inadequate firing time for cold temperature – worked fine with correct time PFR-078 Cable for FGM Mag Boom is discolored Contamination analyzed by GSFC determined not a contamination hazard PFR-079 FM2 FGB fails cold deployment 6/21/05 PFR-080 FGB 2 fails cold deployment 6/22/06 Frangibolts did fire, Operator forgot to remove tape holding booms together PFR-086 Incorrect Deployment Angles in FGM Design Shims added to get correct angles PFR-126 Magnetometer Mount Flatness and clocking Shim to get mounting flat and clocking correct

RFAs, Closeouts, Rework, etc. No Mag Boom RFAs No remaining Closeout Items (except shimming) Rework or replacement of hardware: Frangibolts connectorized on FGB for easier resetting Compliance with Test Verification Matrix Complete Test Margins Adequate margins at Deployment extremes Torque margin worst-case > 3.3 (reqmt >2) Survived vibration and thermal vac @ limits + margin Integration with Probe 3,4 Buses Per thm-mint-proc-026,-027,-037 Units will get 1st motion deployments during probe TV

Appendix 1 Vibration Testing

FM 6 tested to qual levels, FM 1-5 to acceptance levels Vibration Testing Sine Vibration Levels (Ref. Swales SAI-TM-2430-RevD ) FM 6 tested to qual levels, FM 1-5 to acceptance levels

Vibration Testing cont. Random Vibration Levels (Ref. Swales SAI-TM-2430-RevD ) FM 6 tested to qual levels, FM 1-5 to acceptance levels

Vibration Testing Status UPDATE WITH FM 2-6 DTA

Appendix 2 Themal Vac Testing

Thermal Vacuum Testing Test temperatures and Profile: -115C, 4h 75C, 4h 75C, 12h 50C, Hot Deploy -40C, Cold Deploy Restow Qual or acceptance?

SCM/FGM Boom Thermal Testing Status Get updated table from Chris

Strength, Repeatability, and Appendix 3 Strength, Repeatability, and Torque Margin Testing

15 rpm and Repeatability Test Booms hung vertically and weighted so that 1g replicates loads caused by spin accelerations, then dropped from angle that gives correct energy at end of stroke to simulate 15 rpm deployment forces. Boom then dropped 5 times and the rest angles were measured, worst-case variations below.

15 rpm and Repeatability Test continued Drop and repeatibility tests repeated on one unit with angle correction shims to show that shims (added per PFR-086) have no effect on repeatability or strength.

Torque Margin test Minimum Torque Margin = 4.3 This test was run to verify adequate torque margin at worst-case joint at worst-case temperature of -8C and worst-case spin rate of 20rpm (bounce during thrust). Worst-case torque margin of 4.3 meets minimum requirement of 3 Minimum Torque Margin = 4.3 Ts Torque from Spring Tm Torque from Resistive Force on Force Gauge Tc Torque from Centripetal Force on Elbow Arm on Elbow Joint Tf Frictional Torque on Elbow Joint