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Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) Instrument Preliminary Peer Review Mechanisms Patrick Stephens. Outline. Derived Requirements Mechanisms Overview Shutter Mechanisms Interfaces Mechanical Thermal Electrical A1 & A2 Shutters

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  1. Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) InstrumentPreliminary Peer ReviewMechanismsPatrick Stephens

  2. Outline • Derived Requirements • Mechanisms Overview • Shutter Mechanisms • Interfaces • Mechanical • Thermal • Electrical • A1 & A2 Shutters • Motor & Switches • Operation • Materials • Margins • Door Mechanism • Interfaces • Mechanical • Thermal • Electrical • Deployment Envelope • Hinges & Energy Absorber • Pin-Puller & Switch • Materials • Margins • MGSE • Heritage • Testing

  3. Mechanisms Derived Requirements – A1 Aperture

  4. Mechanisms Derived Requirements – A2 Aperture

  5. Mechanisms Derived Requirements – One Shot Door

  6. OverviewMechanisms – A1 Shutter, A2 Shutter, Door Deployment F1775: A1 Shutter Assembly F1770: A2 Shutter Assembly F1780: Door Assembly F1799: Pin Puller Assembly

  7. Shutter MechanismsA1 Aperture – Mechanical Interface • A1 Shutter Assembly (F1775) mounted to Fold Mirror Housing (F1761) • Shutter Cover (F1774) mounted to A1 Shutter Assembly (F1775) F1761: Fold Mirror Housing F1775: A1 Shutter Assembly F1774: Shutter Cover

  8. Shutter MechanismsA2 Aperture – Mechanical Interface • Mounted to Optical Bench (F1759) inside Cover (F1820) & Enclosure (F1809) A2 Aperture (LYOT) F1770: A2 Shutter Assembly F1809: Enclosure F1759: Optical Bench

  9. Shutter MechanismsA1 & A2 Aperture – Thermal Monitoring • Temperature Sensor mounted to Stepper Motor (GD2-A) Temperature Sensor

  10. Shutter MechanismsA1 & A2 Aperture – Electrical Interfaces • Instrument Control Package (ICP) & Stepper Motor Driver (provided by UCB) interface to Motor (GD2-A) & Home Position Switch (9HM30-REL-PGM) • Temperature of Motor • Motor Power • Motor Motion Enable • Motor Phase Count • Home Position Indicator • Shutters controlled independently • +10 VDC ± 1 VDC • Max current 1.3 A • Control Scheme:

  11. Shutter MechanismsDesign – A1 Aperture • F1775 – A1 Shutter Assembly Stepper Motor (GD2-A) Hard Stop (F1764) Shutter Key (F1763) Bracket (F1776) Counterweight (F1769) Shutter (F1762) Home Switch (9HM30-REL-PGM) Hard Stop, Home (F1767)

  12. Shutter MechanismsA1 Aperture – Overall Dimensions & Envelope & Clearances • Clearances • Labyrinth Light Seal • Fold Mirror Housing - .010” clearance • Shutter Cover - .010” clearance • Shutter .015” nominal clearance to Aperture • Adjusted with shim between Motor & Bracket 0.12” 5.85” 2.82” 1.04” 6.20”

  13. Shutter MechanismsDesign – A2 Aperture • F1770 – A2 Shutter Assembly Stepper Motor (GD2-A) Hard Stop (F1764) Home Switch (9HM30-REL-PGM) Shutter Key (F1763) Bracket (F1771) Shutter (F1772) Hard Stop, Home (F1767) Counterweight (F1777)

  14. Shutter MechanismsA2 Aperture – Overall Dimensions & Envelope & Clearances • Clearances • Shutter .015” nominal gap to Aperture • Adjusted with shims / slots .60” 2.78” 2.79” 3.43”

  15. Shutter MechanismsComparison • A1 Shutter encompasses all worst case conditions • Life Cycle Testing only required for A1 Shutter Mechanism

  16. Shutter MechanismsMotor/Gearbox • Stepper Motor (GD2-A) • CDA Intercorp Type 3 Geared Stepper Motor with Detent Brake (3/4” diameter) • ATK-SPEC-2287 & F1779 • Interfaces • Mounts to Shutter Bracket • Shutter mounts to Motor with Shutter Key (Heritage) • Performance

  17. Shutter MechanismsHome Position Switch • Honeywell 9HM30-REL-PGM • Hermetically sealed microswitch • Actuated at Aperture 15% Open • Flight heritage • Micro-D 9 Pin Solder Cup Connector • A1: Transfer signal outside Assemblyto ICP

  18. Shutter MechanismsOn-Orbit Operation • Aperture Fully Open • Capability: A1 Fully Closed • Aperture 15% Open

  19. Shutter MechanismsMaterials and Lubrication • Aluminum 6061-T651 (Black Anodize, MIL-A-8625, Type 2, Class 2) • Most machined parts • Tungsten Alloy (ASTM B777, Class 3, 95%) • F1769 – A1 Shutter Counterweight • F1777 – A2 Shutter Counterweight • CRES 440C • F1766 – Hard Stop • Peelable Aluminum Shim Stock (0.002” Layers) • F1773 – Controls gap between Shutter & Aperture (0.015”) • F1778 – Controls location of Hard Stop (Aperture 15% or fully open) • BraycoteMicronic 600 Lubrication • Contained within Motor

  20. Shutter MechanismsTorque Margins • Flight On-Orbit Loads • Available Torque • Actuation: 48.0 in-oz • Motor Detent Torque: 42.0 in-oz • Resistive Torque • Switch Force: 7 oz • Inertial loads from spacecraft maneuvers imposing torque on shaft: ~ 0 in-oz • Ground Testing Loads • Available Torque • Actuation: 48.0 in-oz • Motor Detent Torque: 42.0 in-oz • Resistive Torque • Switch Force: 7 oz • Shock/vibe loads: 1.31 in-oz * = Margins calculated using GEVS formula

  21. Door MechanismMechanical Interface • Door Assembly (F1780) mounted to top of Baffle (F1758) • Pin Puller Assembly (F1799) mounted to bottom of Baffle F1758: Baffle F1780: Door Assembly F1799: Pin-puller Assembly

  22. Door MechanismThermal Monitoring • Temperature Sensor mounted to Pin-Puller (WI-1688) Temperature Sensor

  23. Door MechanismElectrical Interface • Power and signals to Pin-Puller (WI-1688) & EOT Switch (9HM30-REL-PGM) • Pin-Puller Power • EOT Switch Actuation • Operated with Spacecraft voltage • 28 VDC – 34 VDC • Expected Current 0.8 A – 1.2 A • Pin-Puller Actuator Schematic:

  24. Door MechanismLaunch & On-Orbit Configurations • Launch Configuration • Door Closed • On-Orbit Configuration • Door Open to 49° • 45° Keep Out Zone shown 49° 45°

  25. Door MechanismOverall Dimensions 3.78” • Overall Dimensions 8.58” 4.80” 4.88” 7.41” 2.41” 1.50” 1.42”

  26. Door MechanismDeployment Envelope • Door Deployment Envelope 4.97” 7.10” 0.89” 5.10”

  27. Door MechanismOverall Clearances • Door & Baffle Labyrinth clearances: • 0.030” on all sides of Baffle • 0.020” between front of Baffle and Door 0.020” 0.030” 1.39” .050” 0.12”

  28. Door MechanismDesign – Door Deployment Mechanism • F1780 – Door Assembly Ball Bearings (SSRI-6632ZZ) Energy Absorber Assembly (F1790) Torsion Spring (F1788) Spring Mandrel (F1785) Spring Cap (F1786) EOT Switch (9HM30-REL-PGM) Door (F1782) Door Bracket (F1781) Film Bracket (F1784) Pin-Puller Latch (F1792) Door Film (F1783) Alignment Cone (F1789)

  29. Door MechanismDesign – Door Deployment Mechanism • F1790 – Energy Absorber Assembly: • F1799 – Pin-Puller Assembly: Energy Absorber Shaft (F1796) Energy Absorber Housing (F1791) Energy Absorber Nut (F1796) Compression Spring (KK-7) Energy Absorber (F1793) Pin-Puller (WI-1688, P5 STD) Pin-Puller Bracket (F1798)

  30. Door MechanismDesign – Hinges • Mirrored Parts • Redundant Torsion Springs • Century Spring T0-5160 • Initial Angular Displacement = 240° • Initial Torque = 9.8 in-lb • Pre-Load on Pin-Puller = 1.4 lb • NHBB SSRI-6632ZZ Ball Bearings • Press fit into Door • Pre-load from wave washer & snap ring (1 lb) • Static Load Capacity = 31 lb • Opening Time • Flight: Approx. 1 sec • Ground: Approx. 2 sec • Keep Door open after Deployment • Torque: 5.3 in-lb Wave Washer Snap Ring

  31. Door MechanismDesign – Energy Absorber • Initial Contact with Door • When Door Angle is 92.5° • Door Speed • Flight: 4.0 rad/s max (2.5 in/s) • Ground: 2.0 rad/s max (1.25 in/s) • Energy Absorption • Compression Spring elongates impact • Delrin Pad absorbs energy • Total travel = 0.1” • EOT Switch • Cam on end of shaft against roller leveractuator of switch

  32. Door MechanismDeployment – Pin Puller • Pin Puller – WI-1688, P5 Standard • TiNi Aerospace • Shape Memory Alloy • Interfaces • Mounts to Pin-Puller Bracket (F1798) • Latch (F1792) pre-loaded against pin • Performance

  33. Door MechanismEnd of Travel Switch • Honeywell 9HM30-REL-PGM • Hermetically sealed microswitch • JS-151 auxiliary roller lever actuator • Flight heritage

  34. Door MechanismMaterials & Lubrication • Aluminum 6061-T651 (Black Anodize, MIL-A-8625, Type 2, Class 2) • Most machined parts • CRES 440C • F1785 – Spring Mandrel • F1789 – Alignment Cone • F1795 – Energy Absorber Shaft • Delrin 100AF • F1793 – Energy Absorber • DuPont Tefzel ETFE Film (0.002” thick, coated with 45 Å of aluminum) • F1783 – Door Film • Peelable Aluminum Shim Stock (0.002” Layers) • F1794 – Control location of Latch with respect to pin of Pin-Puller at assembly • F1797 – Control location of Alignment Cone with respect to Pin-Puller Bracket at assembly • Adhesive Paste (EA9394) • Bonding Energy Absorber to Energy Absorber Housing • Dry Film Lube (Everlube 620C) • Lubricated Shaft • Lubricated Alignment Cone surface • Lubricated Latch Surface

  35. Door MechanismForce & Torque Margins • Torsion Springs Torque Margin • Worst Case • One Spring • Door stopped just before Door’s EOT • In contact with Energy Absorber • Available Torque • Initial: 9.78 in-lb • Worst Case: 2.65 in-lb • Resistive Torque: 0.63 in-lb • Bearing Friction & Misalignment & Drag: 0.30 in-lb • Max variable torque from heritage design (MMT Door) • Energy Absorber Compression Spring: 0.15 in-lb • End of Travel Switch • Roller Actuator on Energy Absorber Shaft: 0.09 in-lb • Friction resisting Shaft motion from side load: 0.10 in-lb • Pin-Puller Force Margin • Available Force • Pin-Puller Pull Force: 5 lb • Pin-Puller Side Load during Actuation: 10 lb • Pin-Puller Side Load Non-Actuation: 100 lb • Resistive Force: Spring pre-load & Door mass • Actuation • Friction Force from Latch: 0.54 lb • Side Load Actuation • Normal Force from Latch: 1.81 lb • Side Loan Non-Actuation • Shock/Vibe loads: 24.7 lb * = Margins calculated using GEVS formula

  36. Door MechanismBearing Margins • Worst Case Bearing Loading • All loads applied to Bearings • No loads applied to Pin-Puller Pin or Alignment Cone • Bearings Stress Margins • Preliminary Calculations using COBRA EHL Software • Allowable Hertzian Contact Stress • 335 ksi Maximum (GEVS Requirement) • Worst Case Bearing Hertzian Contact Stress • 293 ksi Maximum • Bearing Force Margins • Allowable Load • 62.0 lb • Applied Load • 17.2 lb

  37. Door MechanismMGSE • Two Counterweights • Moves CG of door to rotation axis • Allows door to open in 1G environment • Required for functional ground testing whenDoor is in vertical orientation • Removed for shock/vibe testing • Tungsten Alloy (ASTM B777, Class 3, 95%)

  38. Heritage • Shutter Mechanism • Derived from ATK’s design of shutter mechanisms for JPL PILA and NASA HST (STIS & COS) programs • Uses identical mounting interface with Shutter / Motor / Shutter Key • Similar COTS stepper motor from CDA Intercorp that operated SHIMMER shutter over 1 million times without anomaly • Door Deployment Mechanism • Derived from ATK’s design of MMT Door andMSO-GRS Anneal Door • Dual rotating hinges • COTS high heritage TiNi SMA Pin Puller

  39. Testing

  40. Test Flow

  41. Torque & Force Margin Testing • Shutter Mechanisms • Actuation Torque Margin • Hang weights on shutters until motor does not rotate when signaled by motor driver • Calculate Torque from weight & moment arm • Detent Torque Margin • Hang weight on shutters until motor rotates when no power is supplied to motor • Calculate Torque from weight & moment arm • Door Mechanism • Torsion Spring Torque Margin • Add weights to door until door does not open in worst case configuration • Calculate torque from weight & moment arm • Pin-Puller Actuation Force Margin • Thread weights into pin until pin-puller does not actuate when signaled • Calculate force from weight • Pin-Puller Side Load Actuation Force Margin • Increase pin pre-load by adding weight to the Door until pin-puller does not actuate when signaled • Calculate pre-load on pin from weights • Pin-Puller Side Load Non-Actuation Force Margin • Testing to failure will cause permanent failure of unit • Door Film • Test to failure by securing to window and applying weights

  42. Future Design Activity • Refine Calculation of On-Orbit Spacecraft Inertial Loads • Refine Calculation of Bearing Loads & Margins • Harness/Wiring Routing • A2 Shutter Wire Pass Through Points

  43. Summary • Design Complies with Driving Requirements • No Technical Issues Identified • Heritage from the PILA, SHIMMER, and MRO-GRS designs Provide Confidence • Simple Mechanisms with Robust Margins • On Schedule to Support Program Needs

  44. AppendixMagnetic Data • Shutter Stepper Motor • Data from CDA testing of similar motor (without detent brake) • CDA does not expect significant increase in magnetic field with detent brake * * 1 Gauss = 100,000 nanoTesla

  45. AppendixTesting GSE • A1 Shutter Mechanism Testing • Mock Fold Mirror Housing interface • Mounting Stand • Stepper Motor Driver provided by UCB • Wiring Harness for switch and motor • Measurement equipment • Electrical Properties • Voltage • Current • Motor Impedance (All windings) • Actuation Times (All positions) • Home Position Switch Sensitivity • A2 Shutter Mechanism Testing • Mock Optics Bench interface • Mounting Stand • Stepper Motor Driver provided by UCB • Wiring Harness for switch and motor • Measurement equipment • Electrical Properties • Voltage • Current • Motor Impedance (All windings) • Actuation Times (All Positions) • Home Position Switch Sensitivity • Door Mechanism Testing • Counterweight • Mock Baffle interface • Mounting Stand • Testing harness for actuator and switch • Manual Reset Tool provided by TiNi • Measurement equipment • Electrical Properties • Voltage • Current • Resistance • Actuation Times • EOT Switch Sensitivity

  46. AppendixStepper Motor

  47. AppendixStepper Motor

  48. AppendixStepper Motor

  49. AppendixStepper Motor

  50. AppendixPin-Puller

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