1. MAVEN PFP Mechanical Peer Review SEP (Solar Energetic Particles) Instrument May 10, 2010 David Glaser Davin Larson Robert Lillis Paul Turin David Curtis

2. 2 PFP Mechanical Peer Review – May 10, 2010 Overview Background: THEMIS SST –Flight Heritage –Mechanical Design Proposed Design Changes for MAVEN SEP –Science Driven –Improved Assembly –Spacecraft Driven

3. 3 PFP Mechanical Peer Review – May 10, 2010 Background: THEMIS SST SEP will be much the same as the Solid State Telescope (SST) on THEMIS

4. 4 PFP Mechanical Peer Review – May 10, 2010 Background: THEMIS SST Flight Heritage 10 SSTs were flown on THEMIS – 2 on each Spacecraft Mechanical design has performed well on all instruments Solid Models, drawings, and assembly procedures are well documented Most of SST design team is present Design Team Davin Larson – Lead Scientist Robert Lee – Lead Mechanical Engineer (no longer at SSL) Paul Turin – Supporting Senior Mechanical Engineer Craig Tindall (LBL) – Detector Design/Fabrication

5. 5 PFP Mechanical Peer Review – May 10, 2010 SST Mechanical Design SST Sensor Unit –DFE (Detector Front End) Subassembly –Magnet-Yoke Subassembly –Attenuator-Actuator Subassembly –Collimators –Support Structure –Bi-Directional FOV Attenuator Actuation –Linear Actuators –Position Switches Attenuator Control Thermal Shield Sensor Orientation on Spacecraft

6. 6 PFP Mechanical Peer Review – May 10, 2010 Sensor Unit Schematic The Solar Energetic Particle (SEP) instrument measures the energy spectrum and angular distribution of solar energetic electrons (30keV–1 MeV) and ions (30 keV-12 MeV). Foil Collimator Thick Detector Sm-Co Magnet (sweeps away electrons <350 keV) Attenuator Al/Polyamide/Al Foil (stops ions <350 keV?) Open Detector Attenuator Open Collimator Foil Detector Ions Electrons

7. 7 PFP Mechanical Peer Review – May 10, 2010 Sensor Cross Section Attenuator Foil Magnet Detector Stack Attenuator Foil Collimator Open Collimator

8. 8 PFP Mechanical Peer Review – May 10, 2010 Typical Electrical Connection Between Detector and Flex-Circuit SST Mechanical Design Kapton Flex-Circuit Detector (pixelated side) Wirebond Loop (NOT to scale – actual loop height < 300 micron)

9. 9 NGIMS MSR, 10/19/2009 Detectors (4) Spring Clamp Spring Plate (2) Detector Board Composition (exploded view) PEEK Spacer (4) BeCu Gasket (3) Kapton Flex-Circuit (4)AMPTEK Shield Kapton Heater Thermostat DFE Board Subassembly SST Mechanical Design

10. 10 NGIMS MSR, 10/19/2009 DFE Board Subassembly Relative Positions (2 per sensor) AMPTEK Shielding Detector Stack Subassembly Multi-Layer Circuit Board (62 mil thickness) Foil Frame Thermostat SST Mechanical Design

11. 11 NGIMS MSR, 10/19/2009 Magnet-Yoke Assembly Co-Fe Yoke (2) Sm-Co Magnet (4) (currently not visible) Aluminum Magnet Cage SST Mechanical Design

12. 12 NGIMS MSR, 10/19/2009 Attenuator Assembly Attenuator (4) Cam (2) SMA Lever (2) SST Mechanical Design

13. 13 NGIMS MSR, 10/19/2009 Actuators and Position Switches Honeywell SPDT Hermetically Sealed Switch (2) SMA Actuator (2) SST Mechanical Design

14. 14 NGIMS MSR, 10/19/2009 Two Collimators Per Side Electron Side Ion Side SST Mechanical Design

15. 15 NGIMS MSR, 10/19/2009 Four Collimators Per Sensor Ion Side Electron Side Ion Side SST Mechanical Design

16. 16 NGIMS MSR, 10/19/2009 Support Structure (back section) Electrical Connector Bottom Closeout Panel Rigid Mounting Flange SST Mechanical Design

17. 17 NGIMS MSR, 10/19/2009 Support Structure (front section) Kinematic Flexure (2) Rigid Mounting Flange SST Mechanical Design

18. 18 NGIMS MSR, 10/19/2009 Bi-Directional Fields-of-View SST Mechanical Design

19. 19 NGIMS MSR, 10/19/2009 Sensor Unit Mounting Using Kinematic Flexures –Each sensor mounted to spacecraft panel at three points One rigid mounting flange Two mounting flanges with kinematic flexures –Allows relative motion due to CTE differences between sensor structure and spacecraft panel Predicted expansion differential along instrument axes with 120 ºC temperature gradient: –X-Axis: 0.006” (0.15 mm) –Y-Axis:0.013” (0.33 mm) –Flexure dimensions sized to keep maximum bending stresses below 6061-T6 yield strength Factor of Safety (F.S.) > 1.4 per NASA-STD-5001 SST Mechanical Design

20. 20 NGIMS MSR, 10/19/2009 Attenuator Actuation – CLOSED position Honeywell Switch (extended-position) SMA Actuator (extended) Honeywell Switch (compressed-position) SMA Actuator (retracted) SST Mechanical Design

21. 21 NGIMS MSR, 10/19/2009 Attenuator Actuation – OPEN position Honeywell Switch (compressed-position) SMA Actuator (retracted) Honeywell Switch (extended-position) SMA Actuator (extended) SST Mechanical Design

22. 22 NGIMS MSR, 10/19/2009 Attenuator Control – CLOSED to OPEN (INITIAL) CLOSE Attenuator OPEN Attenuator PCB +5V SEP Sensor +5V GND Monitor PCB SPDT Switch FREECOMPRESSED CC NC NO FRONT SMA (ACTIVE) BACK SMA HIGHLOW SST Mechanical Design

23. 23 NGIMS MSR, 10/19/2009 Attenuator Control – OPEN to CLOSED (INITIAL) PCB +5V SEP Sensor +5V GND Monitor PCB SPDT Switch CLOSE Attenuator OPEN Attenuator COMPRESSEDFREE CC NC NO FRONT SMABACK SMA (ACTIVE) LOWHIGH SST Mechanical Design

24. 24 NGIMS MSR, 10/19/2009 SST Mechanical Design Thermal Shielding Box was added after CDR Silver Teflon Tape

25. 25 NGIMS MSR, 10/19/2009 SEP Mechanical Design Sensor Orientation Relative to Spacecraft Bus

26. 26 PFP Mechanical Peer Review – May 10, 2010 MAVEN SEP SEP – Solar Electric Particle Instrument Largely identical in mechanical design to SST with a few small changes Flight heritage will allow rapid development of engineering and flight instrument models

27. 27 PFP Mechanical Peer Review – May 10, 2010 MAVEN SEP Mechanical Design Team Davin Larson – Lead Scientist Robert Lillis – Research Scientist David Glaser – Mechanical Design Paul Turin – PFP Mechanical Lead Craig Tindall (LBL) – Detector Design/Fabrication

28. 28 PFP Mechanical Peer Review – May 10, 2010 MAVEN SEP Mechanical Work to Date Weekly meetings since February 2010 Compiled a list of desired improvements Preliminary Designs of Improvements made in SolidWorks Drivers of Design Changes Improve science capability Improve ease of assembly Spacecraft Driven

29. 29 PFP Mechanical Peer Review – May 10, 2010 SEP Design Changes from SST 1.Increase Detector Area in Y dimension 2.Increase Collimator FOV in Y dimension 3.Add relief in magnet cages to reduce unwanted reflections 4.Move detector foils closer to detectors 5.Change foil thickness from 4.3µm to 2µm (?) 6.Eliminate electron side attenuator (?) 7.Blacken the attenuator paddle 8.Reverse attenuator pinhole angle (?) 9.Change Detector Stack Holder from PEEK to brass 10.Change soldered detector connections to spring loaded buttons 11.Change from one 26-pin connector to two 21-pin connectors 12.Change Attenuator Winchester Connectors from 4-pin to 2-pin 13.Removal of heater and thermostat from Amptek Amplifiers 14.Survival Heaters added to housing exterior 15.Minor changes to thermal protection box (reflect changes in allowable instrument footprint) 16.Change Purge System Science Assembly Spacecraft

30. 30 PFP Mechanical Peer Review – May 10, 2010 MAVEN SEP Science Driven Changes How can the science data be increased/improved without inducing any major design changes to the instrument? 1.Increase the FOV 2.Try to reduce scattered light reaching the detector

31. 31 PFP Mechanical Peer Review – May 10, 2010 1. Increase Detector Size in Y Direction 7 mm 8.2 mm Design Changes from SST SST Active Detector Area: 92.4 mm 2 SST Active Detector Area: 108.2 mm 2 17% Larger 13.2 mm

32. 32 PFP Mechanical Peer Review – May 10, 2010 2. Increase Collimator FOV in Y Direction Design Changes from SST SST 40° x 23° SEP 40° x 31°

33. 33 PFP Mechanical Peer Review – May 10, 2010 2. Increase Collimator FOV in Y Dimension Design Changes from SST SST FOVs were 6° and 23°, are now 11° and 31° Baffles and Collimator Apertures Enlarged in Y Dimension

34. 34 PFP Mechanical Peer Review – May 10, 2010 2. Increase Collimator FOV in Y Direction Design Changes from SST Path to DetectorAt Sun Angles Less Than Direct15.5° 1 Bounce – Magnet Cage~25° 1 Bounce – Outer Baffle Edge 15° Sunlight Reaching the Detector Nominal Sun Angle is 45° from instrument axis

35. 35 PFP Mechanical Peer Review – May 10, 2010 3. Add Relief in Magnet Cages – to Reduce Reflections Inner Surface of Magnet Cage Can Reflect to Detector Design Changes from SST

36. 36 PFP Mechanical Peer Review – May 10, 2010 Design Changes from SST Surfaces Relieved By.010 inches (Material Thickness Changed from.030” to.020”) 3. Add Relief in Magnet Cages – to Reduce Reflections

37. 37 PFP Mechanical Peer Review – May 10, 2010 4. Move Foils Closer to Detectors – To lose fewer electrons to scattering Original Distance: 0.29 inches (7.4 mm) Design Changes from SST Foil Detector

38. 38 PFP Mechanical Peer Review – May 10, 2010 4. Move Foils Closer to Detectors Design Changes from SST

39. 39 PFP Mechanical Peer Review – May 10, 2010 4. Move Foils Closer to Detectors New Distance: 0.07 inches (~1.8 mm) Design Changes from SST Foil (5. Change thickness of foil (?)) Detector Detector Stack Holder (9. Changed from PEEK to Brass) New location: beneath stack holder Issue: Detector Vents are covered up by foil frame

40. 40 PFP Mechanical Peer Review – May 10, 2010 6. Eliminate Electron Side Attenuators (?) -Predicted electron fluxes indicate attenuator may not be necessary Design Changes from SST

41. 41 PFP Mechanical Peer Review – May 10, 2010 7. Blacken Attenuator Paddles 8. Reverse Angle of Attenuator Aperture (?) Design Changes from SST Current SolidWorks Model Incoming particles can reflect from sides of aperture Aperture reversed – less opportunity for reflection from sides

42. 42 PFP Mechanical Peer Review – May 10, 2010 MAVEN SEP Instrument Assembly Driven Changes

43. 43 PFP Mechanical Peer Review – May 10, 2010 10. Improve Upon Soldered Detector Connections Original Design - Contacts were soldered together Design Changes from SST Kapton Flex Circuits BeCu Spacers

44. 44 PFP Mechanical Peer Review – May 10, 2010 New Design – Contacts via Spring Buttons Design Changes from SST Gold Plated Brass Button Contacts Flex Circuit Above Gold Plated Stainless Spring – Squared End Contacts Pad on Board OD.080” Spring Deflection: 0.025” Spring Force: 0.58 lb Contact Stress: ~1000 psi 10. Improve Upon Soldered Detector Connections

45. 45 PFP Mechanical Peer Review – May 10, 2010 Design Changes from SST Flex Circuits Pressed Down on Spring Buttons by an Aluminum Clamp 10. Improve Upon Soldered Detector Connections Flex Circuit Tabs Shortened Pads on Flex Circuits Enlarged

46. 46 PFP Mechanical Peer Review – May 10, 2010 11. Change from one 26-pin connector to two 21-pin connectors (one for each DFE Board) Design Changes from SST SST SEP

47. 47 PFP Mechanical Peer Review – May 10, 2010 12. Change Attenuator Winchester Connectors from 4- Pin to 2-Pin - extra pin was used for a monitor, smaller connector occupies less space Design Changes from SST 11. Change from one 26-pin connector to two 21-pin connectors (one for each DFE Board)

48. 48 PFP Mechanical Peer Review – May 10, 2010 11. Change from one 26-pin connector to two 21-pin connectors Design Changes from SST Each connector is mounted to its DFE board Glenair Micro-D 21-pin Right Angle PCB Mount Connector Nut Plate (2-56 tapped holes)

49. 49 PFP Mechanical Peer Review – May 10, 2010 MAVEN SEP Changes Driven by MAVEN Spacecraft

50. 50 PFP Mechanical Peer Review – May 10, 2010 Design Changes from SST 13. Remove Heater and Thermostat from Amptek Boxes - Because of spacecraft harnessing and also reduces noise Kapton Heater Thermostat SST DFE Board

51. 51 PFP Mechanical Peer Review – May 10, 2010 14. Add Survival Heaters to Housing Exterior Design Changes from SST Two 1-2 W heaters (Location TBD)

52. 52 PFP Mechanical Peer Review – May 10, 2010 15. Minor Changes to Thermal Shield Assembly Design Changes from SST SST SEP Bevel was necessary on THEMIS due to space constraints on instrument platform

53. 53 PFP Mechanical Peer Review – May 10, 2010 16. Change Purge System Design Changes from SST THEMIS SST had remove-before-flight N 2 purge hardware MAVEN SEP will require a hard plumbed system on the instrument Redesign not done yet THEMIS SST N 2 Purge System

54. 54 PFP Mechanical Peer Review – May 10, 2010 Summary/Conclusion THEMIS SST provides successful heritage to SEP Only minor modifications are necessary Need to be careful to follow most recent SST design and procedures when documentation is not clear