THEMIS PER 1 UCB, May 02, 2005 Magnetometer Booms Pre Environmental Review Prof. Hari Dharan Berkeley Composites Laboratory (Presenter: David Pankow) Department of Mechanical Engineering University of California at Berkeley

THEMIS PER 2 UCB, May 02, 2005 Mag Boom Requirements

THEMIS PER 3 UCB, May 02, 2005 Qualification Test Sequence Proof test of composite boom tubes Ambient, off-loaded deployment testing (e.g. 0 rpm) Qualification level vibration testing  Ambient, off-loaded deployment testing (e.g. 0 rpm)  Thermal vacuum testing (cycling + deployments) Weighted drop test (e.g. 15 rpm max) Ambient, off-loaded deployment testing (e.g. 0 rpm)

THEMIS PER 4 UCB, May 02, 2005 Vibration Sine Vibration Levels (Ref. Swales SAI-TM-2430-Rev D ) First Mode in Mag Booms is  100 Hz  8 G Rigid Body Motion

THEMIS PER 5 UCB, May 02, 2005 Vibration Random Vibration Levels (Ref. Swales SAI-TM-2430-Rev D ) TEST RESPONSEX axisY axisZ FGM Sensor30.4 Grms36.4 Grms27.8 SCM Sensor27.3 Grms20.6 Grms21.5 Grms

THEMIS PER 6 UCB, May 02, 2005 Vibration Testing DateResultCorrective Actions 2/28/05Mounting bolts for SCB DAD tower not torqued properly. SCB DAD tower failed in Y axis. Use torque-limiting screwdriver with extension driving bits. 3/02/05Fatigue damage observed (between tests) in SCB base bracket’s near foot, Add fillet to corner of near foot to reduce stress concentration. 3/07/05Fatigue damage observed (between tests) in SCB base bracket’s near foot above fillet. Add fillets to corner of both feet to reduce stress concentration. Add larger steel washers and G10 isolators to completely support feet. 3/11/05Deformation observed (between tests) in SCB base bracket’s far foot. Retrofit base with wider feet. 3/23/05Fatigue damage observed in SCB DAD tower’s feet.Replaced with redesigned DAD tower with wider feet. 3/29/05Booms complete vibration qualification and are tested in TV to determine functionality at hot and cold extremes. SCB has increased friction. FGB has loss of preload in frangi-bolt ring from stripped threads in frangi-bolt ring (Build/Test Mistake) Add deployment testing after vibration and before TV testing. Tightened spool to holds the base spring subassembly. 4/08/05  5% Frequency shift with no visible damage. SS washers added to (non-load bearing) surfaces to eliminate observed fretting. 4/25/05Similar frequency shift in SCB after first X random test. Abnormal frequency response caused by G10 spacers. Booms survived structurally but increased friction was noted during subsequent deployment. Frequency response stable after second random vibration G10 spacers were removed prior to continuing with vibration Lubrication and improvement of rubbing surfaces Offloading force incorrect during deploy. Booms deploys when offload corrected. Next (and last ?) F1 MB qual. vibration test is scheduled for this Friday, May 6

THEMIS PER 7 UCB, May 02, 2005 Vibration Testing Flexible Feet for CFRP Deck CTE mismatch Axial Load Bearing Shaft Interface NON - Load Bearing Interface BASE HINGE VIBRATION PROBLEMS ILLUSTRATION

THEMIS PER 8 UCB, May 02, 2005 PFR StatusTitle PFR-025CLOSEDCracked feet in SCB frangibolt/DAD tower PFR-027CLOSEDCracked Base Bracket in SCB PFR-035CLOSEDSpring spool in SCB base hinge loosened by vibration. PFR-036CLOSEDDamaged threads in FGB frangibolt ring. F1 booms re-designated F6 flight spare because of the accumulated random vibration time

THEMIS PER 9 UCB, May 02, 2005 SCM/FGM Boom Thermal Testing Status

THEMIS PER 10 UCB, May 02, 2005 Thermal Vacuum Testing -115C, 4h 75C, 4h -115C, 4h 75C, 4h 75C, 12h 50C, Hot Deploy -40C, Cold Deploy Restow

THEMIS PER 11 UCB, May 02, 2005 Thermal Vacuum Joint sample of representative joint and carbon tube tested to –135  C to 65  C. Mag booms survived one cycle of temperature extremes (-115  to 75  C) + subsequent re-vibration. Frangibolt actuator survived temperature extremes. Both booms failed subsequent deployment FGM due to the previously stripped thread SCM due to excessive drag from off loading GSE.

THEMIS PER 12 UCB, May 02, 2005 BACKUP SLIDES Bob Coladonato (GSFC ret.) on the FEMCI Website ONE MAN’S (controversial ?) OPINION

THEMIS PER 13 UCB, May 02, 2005 BACKUP SLIDES ANOTHER MAN’S (controversial ?) OPINION David, I don't know where you are in the THEMIS I&T process, but let me suggest, in the interest of saving the time and money associated with unnecessary test failures, that you not test the components and instruments to the high random vibration levels that Swales was proposing when I did that vibro-acoustic study for you a year or so ago. Rather, vibration test the components and instruments for workmanship, and then do acoustic tests of the individual probes and bus, and then an acoustic test, and perhaps a random vibration test, of the assembled spacecraft. If Frank Snow balks at this "deferred risk" approach, remind him of his ACE spacecraft project, where the flight data gathered by the GSFC onboard measurement system (SLAM) showed that the flight acoustic and random vibration levels were 20 dB below the test levels. (and, Ed Stone's, CHRIS instrument had a failure during its high level random vibration test, in spite of force limiting.) Best Regards, Terry Scharton (JPL ret. - “the invaluable maverick”) 30 Mar 2005