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RBSP Electric Field and Waves Instrument (EFW)

RBSP Electric Field and Waves Instrument (EFW). Boom Systems Mechanical Overview, Testing, and Thermal Design Paul Turin Lead Mechanical Engineer SSL/UCB. EFW Structural/Mechanical Sub-System. Topics: EFW Mechanical Overview Personnel Suite configuration Boom introduction Heritage

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RBSP Electric Field and Waves Instrument (EFW)

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  1. RBSPElectric Field and Waves Instrument(EFW) Boom Systems Mechanical Overview, Testing, and Thermal Design Paul Turin Lead Mechanical Engineer SSL/UCB EFW INST+SOC PDR

  2. EFW Structural/Mechanical Sub-System Topics: • EFW Mechanical Overview • Personnel • Suite configuration • Boom introduction • Heritage • Design requirements • Mass budget • Schedule • Environments and Testing Overview • ETM • Vibration • TV • Deployments • Instrument Thermal Modeling EFW INST+SOC PDR

  3. EFW Overview:Personnel • Lead Mechanical: Paul Turin • SPB Mechanical: Greg Dalton • AXB Mechanical: Jeremy McCauley • IDPU Mechanical: Bill Donakowski • Thermal: Chris Smith • Dynamics, Mechanical Greybeard: David Pankow EFW INST+SOC PDR

  4. EFW Overview:Configuration on the RBSP Spacecraft REVISED Spacecraft +Z EFW INST+SOC PDR

  5. EFW Overview:Configuration on the RBSP Spacecraft NEW +Z AXB mounting tube AXB mounting tube AXB sensor sphere IDPU AXBs SPBs SPBs EFW INST+SOC PDR

  6. EFW Overview:Boom Numbering EFW INST+SOC PDR

  7. EFW Overview:Spin Plane Booms REVISED Stowed • Four Spin Plane Booms (SPBs) • Orthogonal pairs 80m/100m tip-to-tip • Sensor spheres at end • Preamps 3m inboard Deployed Doors Wire(40/50m) Fine wire (3m) Preamp Sensor sphere EFW INST+SOC PDR

  8. EFW Overview:Axial Booms Sensor sphere/preamp Whip Two booms in mounting tube Whip hinge Mounting tube Deployed Stacer Single boom stowed • Two Axial Booms • 12m Tip-to-tip maximum • Sensor spheres at tips, Preamps in spheres • Lengths individually adjustable (longer only) on orbit to allow compensation for SC charging Fully deployed EFW INST+SOC PDR

  9. EFW Overview:UCB/SSL Boom Heritage Spacecraft SPB’s Stacers S3-2 4 S3-3 4 2 ISEE 2 VIKING 4 FREJA 6 FIREWHEEL* 2 CRRES 2 POLAR 4 FAST** 4 2 CLUSTER I* 16 CLUSTER II 16 THEMIS 20 10 SPARES 26 6 Demeter 4 STEREO 8 (Sounding Rockets) (~60) ----- ----- Total built and qualified 110 36 (+ 60) Flown to orbit: 92 36 Successfully deployed: 91 35 Broken wires: 0 * LAUNCH FAILURE ** Double-sphere SPB failed to deploy. This design retired. One AXB was not deployed until end of mission. Firing circuit optocouplers failed due to 10 yr radiation exposure. EFW INST+SOC PDR

  10. EFW Overview:Design Requirements • References, Standards, and Requirements • RBSP 7417-9013 Mission Requirements Document • RBSP-EFW-SYS-001D Instruments Requirements Document • RBSP 7417-9019 Environmental Design and Test Requirements Document • RBSP 7417-9018 Electro-Magnetic Environments • GSFC-STD-7000 General Environmental Verification Specification • NASA-STD-5001 Structural Design And Test Factors Of Safety • GSFC-STD-1000 Golden Rules EFW INST+SOC PDR

  11. EFW Overview:Design drivers • Load factors • APL required limit load = 30g • We feel should be based on 5s: 10.4grms x 5s = 52g (Themis test data) • 52g x 1.4SF = 78g -- Our design starting point is 100g • Required structure stiffness – first mode over 50Hz • We design for 100Hz min • Torque/force margins per GSFC-STD-7000 (GEVS) 2.4.5.3 (typically >3@PDR) • Conductive exterior surfaces per RBSP 7417-9018 EME • Magnetically shielded motors per RBSP 7417-9018 EME • Same design as THEMIS which had a stricter spec • Redundant locking features on fasteners • We use combinations of torquing, Spiralock, locking inserts, and staking • Design safety factors per RBSP 7417-9019 table 5-6 EFW INST+SOC PDR

  12. EFW Overview:Mass Budget REVISED EFW INST+SOC PDR

  13. EFW Overview:Boom PDR Milestones EFW INST+SOC PDR

  14. EFW Environmental Test Overview REVISED • Instrument Level • Functional testing • Deployments • Torque margins • Vibration testing • Waiver for unpowered testing (we’re off for launch) • We prefer to test ETUs to qual levels and flight units to acceptance (asuming no significant changes). APL has specified protoflight tests. To be resolved by MPDR. • TV • Hot and cold deployments • Mass props • Knife edge CG determination +-.25in. • Torsional pendulum for MOIs +-10% • Pressure profile testing • We use 1in2 vent area per 1ft3 box volume rule of thumb, no analysis or test. Will request waiver • Self-induced shock • At the instrument level, not at observatory level due to deployment limitations. Will request waiver • No acoustics testing – no acoustically sensitive components • Suite level • No boom deployments at suite level – use simulators to exercise electrical services • Observatory Level • Observatory shock test • Waiver for boom walkout requirement – not practical for Stacers • Simulators incorporating Frangibolts will be provided for end-to-end electrical service tests • A partial deployment of the SPBs will be performed at EMC -- Doors opened, ~5m of wire deployed EFW INST+SOC PDR

  15. EFW Environmental Test Matrix EFW INST+SOC PDR

  16. EFW Vibration testing • Test levels per RBSP 7417-9019 • Pre and post sine surveys (1/4g) • Sine sweep per table 5-9 • Random currently per tables 5-11 & 12 • APL has specified protoflight tests. We prefer to test ETUs to qual levels and flight units to acceptance (assuming no significant changes). Under negotiation. • AXBs will be vibrated individually. • Mounting tube and mass dummies will be provided to APL by Fall 2009 for inclusion in SC structural loads testing. • We will use force limiting for all tests • Testing performed at Quanta Labs, Santa Clara, CA • Performed >70 tests for THEMIS • All units powered off during tests • Waiver required. Off during launch. EFW INST+SOC PDR

  17. EFW Thermal Vacuum Testing • Test levels per RBSP 7417-9019 • AXB stacer unit and whip to be tested separately because of deployment offloading reqm’ts • Preamps tested separately prior to boom testing because of much wider temp swings • Hot and Cold Deploys • No thermal balance tests • All units have thermally conductive interfaces • Balance done at observatory level EFW INST+SOC PDR

  18. EFW Deployment Testing REVISED • ETU and Flight Deployment testing • Post assembly – ambient functional deployments • Force margin tests • Thermal Vacuum -- Hot and cold deploys (post vibe) • Observatory level • Spacecraft/Observatory test plan under discussion with APL, a waiver will be required • Due to impracticality of SC level full deployments: • Partial deployment of SPBs during EMC for radiated emissions test • Simulators for SPB doors and motors, AXB whip and stacer deployments in TV • This scheme followed on POLAR, FAST, CLUSTER, THEMIS • Following deployment, SPBs removed, restowed, spheres cleaned or replaced if surface marred • Additional tests • SPB Wire length calibration • SPB Fine wire pullout force profile and margin check • Wire EOT switch test • Motor, pinpuller current profile EFW INST+SOC PDR

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