Outline

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

2. Outline • MIGHTI Overview • Thermal Requirements • Level 4 – Direct • Level 5 Derived • Temperature Limits • Design Approach – Overall • Thermal Design • Heat Pipe / Radiator Assembly • TEC to Heat Pipe Interface • Camera Housing • Optical Bench • Interferometer • Aft Optics • Baffle • Camera Electronics • Calibration Lamp • Mechanisms • Thermal Control Hardware • Thermal Model • Geometric Configuration • Giver-Receiver Information Exchange • Assumptions • Thermal Analysis • Results Summary • TEC Dissipation • Transient Results • Trade Studies • Testing • Plan Forward

3. MIGHTI Overview (1 of 3) ICON • MIGHTI is a key instrument on the NASA Class C Ionospheric CONnection Explorer (ICON) Mission headed by the Space Sciences Laboratory (SSL) at UC Berkeley (Dr. Immel, PI) • MIGHTI is a limb imager with two orthogonal fields of view measuring velocity and direction of the thermospheric wind using the atomic Oxygen red and green lines (630.0 nm & 557.7 nm) and the temperature using the molecular Oxygen atmospheric (A) band (762 nm). • ICON Spacecraft Bus Developed by Orbital • MIGHTI is based off the heritage designs of the SHIMMER instruments successfully flown on STS-112 (2002) And STPsat-1 (2007) 630.0nm 557.7nm 762.0nm MIGHTI Behind (B) MIGHTI Ahead (A)

4. MIGHTI Overview (2 of 3) • Camera Electronics box with an integral radiator • Calibration Lamp – Light source for calibration optics on both MIGHTIs • Two identical MIGHTI instruments, located at 90°±5° • 575km Circular Low Earth Orbit • TBD Launch Vehicle – Pegasus Class (Mass Limitations) • Accelerated Schedule: • MIGHTI PDR = 4/22/14 • MIGHTI CDR = 11/25/14 (Tentative) • MIGHTI PER = 7/9/15 (Tentative) • MIGHTI Instrument Delivery to U.C. Berkeley for Integration with Other Payloads = 11/23/15

5. MIGHTI Overview (3 of 3) – Instrument Layout One Shot Door Radiator Baffle Assembly Heat Pipe Stepper Motor Control Calibration Optics Entrance Pupil & Shutter Housing Optical Bench Transfer Optics Enclosure Optics Enclosure Camera/Heat Pipe Interface Instrument Flexures (2) near side (2) far side Camera

6. Thermal Requirements: Level 4 – Direct (1 of 3)

7. Thermal Requirements: Level 4 – Direct (2 of 3)

8. Thermal Requirements: Level 4 – Direct (3 of 3)

9. Thermal Requirements: Level 5 – Derived (1 of 2)

10. Thermal Requirements: Level 5 – Derived (2 of 2)

11. Thermal Requirements: Temperature Limits

12. Design Approach– Overall • Optical Bench Assembly • Thermally isolate from PIP & Baffle • Software (ICP) controlled active heater control to maintain temperature stability • Radiators sized to maintain active heater control margin (>30%) for all on orbit hot-cold operational conditions (MLI on non-radiating surfaces • Radiator, heater, and temperature sensor locations optimized to minimize spatial temperature gradients • NOTE: Design pending completion of ongoing analysis • Camera CCD • Thermally isolated TEC for CCD active thermal control; camera internal design by SDL • Fin radiator heat pipe assembly to transport and reject TEC dissipation and associated parasitic loads • Electronics • Passive radiator design; radiators sized to protect hot case limits (MLI on non-radiating surfaces) • Thermostat controlled operational heaters to protect cold limits as required • Thermostat controlled heaters to protect survival temperature limits • NOTE: survival / safe-mode analysis pending • Structure • MLI to damp orbital (day-night) temperature excursions

13. Thermal Design – Heat Pipe / Radiator Assembly • Fin Radiator • (2) 1/16” thick 6061 Al face-sheets • 2.4 PCF Al core • A = 2 x 144 in2 • Z93 white paint; both sides • Thermal isolation at supports (4 places) • Titanium flexure supports (2) • Heat Pipe • Dual bore 0.75” x 0.375” Al extrusion • Working fluid ammonia • he / hc = 1.5 / 2.5 W/in/oC • In plane • Exposed length MLI • Embedded in radiator core • Bonded to radiator face-sheets (2) • 3/8” contact (2 sides) along radiator full length

14. Thermal Design – TEC to Heat Pipe Interface • Heat pipe clamp assembly • Thermally isolated from bench • Thermal design pending • TEC hot side interface • SDL design • need mCp = 119 J/oC • See power dissipation table in thermal model assumptions section • Heat pipe evaporator flange • Acontact = 1.75” x 2.75” • thermal gap filler h = 2.5 W/in2/oC • Heat pipe clamp / saddle • Mass to damp orbital transient temperature swings • Beryllium • m = 0.073 kg (0.016 lb) • Material optimized to minimize absolute mass while maximizing thermal mass (mCp)

15. Thermal Design – Camera Housing • Camera Housing • Thermally isolated from bench • <0.05 W/oC; verification/margin pending bench detailed analysis • 560 mW internal electronics dissipation • Housing radiator area Z93 white paint or Ag Teflon tape • Partial radiator area on 2 sides shown • Required radiator area pending analysis • Non-radiator area and cabling MLI • MLI light seal at camera / bench interface • Thermostat controlled operational / survival heaters as required Partial radiator area 2 sides TEC hot side interface

16. Thermal Design – Optical Bench • Optical Bench • Thermally isolated from PIP • Machined 6061 Aluminum • Internal dissipation negligible • Active heater control • Up to 3 operational circuits • Operational heaters software controlled • Operational heaters maintain 20oC +/- 2oC; transient & spatial • Heaters designed to maintain continuous active control (hot-cold environment range) • Design margin 30% • Survival heaters thermostat controlled • Heater size/location definitions pending ongoing analysis • Z93 white paint structure radiators • Radiator design & analysis ongoing • Non-radiating surfaces MLI • Interior high emissivity • Cover (not shown) • Passive • Diffuse high emissivity interior • MLI on outside surfaces Interferometer Oven Camera Bench

17. Thermal Design – Interferometer • Interferometer • Thermally isolated from support structure • No internal dissipation • Cover • Thermally coupled to base plate • Active heater control; 3 temperature sensors • 2 high resolution; 1 low resolution • 1 heater circuit (multiple heaters) • Operational heaters maintain 25oC +/- 0.1oC; transient & spatial • Operational heaters designed to maintain continuous active control • Design margin 30% • Heater size/location definitions pending ongoing analysis • Outside surface MLI • Inside surface diffuse / high e • Base Plate • Thermally isolated from bench • Bottom side facing bench Al tape (low e) • Top side facing interferometer diffuse / high e Cover Top Plate Fixed Top Interferometer Contacts Interferometer Base Plate Spring Loaded Bottom Interferometer Contacts Thermal Isolators

18. Thermal Design – Aft Optics • Aft Optics & Shutter Housing • Thermally coupled to bench • Thermally isolated from baffle • Internal dissipation negligible • Single temperature sensor • Active heater control • 1 circuit (design pending analysis) • Operational heaters software controlled • Operational heaters maintain 20oC +/- 2oC; transient & spatial • Heaters designed to maintain continuous active control (hot-cold environment range) • Design margin 30% • Survival heaters thermostat controlled • Survival heater circuit combined with bench • Heater size/location definitions pending ongoing analysis • Z93 white paint structure radiators • Radiator design & analysis ongoing • Non-radiating surfaces MLI • Interior high emissivity Entrance Pupil & Shutter Housing Stepper Motor Aft Optics Enclosure

19. Thermal Design – Baffle • Baffle Structure • Thermally isolated from Aft Optics • Thermally isolated from supports • Passive thermal control • High emissivity interior • MLI on outside surfaces

20. Thermal Design – Camera Electronics • CEB radiator • 12 W internal electronics dissipation • Assumed dissipation at radiator • Z93 white paint on front and fin back • CEB housing • Thermally isolated from PIP • Model assumes no conduction to PIP (conservative) • PIP temperature range -20oC to +40oC per SSL/Berkley • Interface conductance requirement TBD by SDL & SSL/Berkley • Housing and cabling MLI • Thermostat controlled survival heaters as required

21. Thermal Design – Calibration Lamp • Lamp Housing • 8 W internal electronics dissipation • Assumed dissipation uniform over housing • Ag Teflon tape on housing • Thermally isolated from PIP • <0.05 W/oC • cabling MLI • Thermostat controlled survival heaters as required

22. Design Approach – Mechanisms • Aperture Door • Thermal design & analysis pending • Deployment heater as required • Stepper Motors • Thermal analysis pending • Aft optics motor MLI • Bench Motor radiates to OB cavity • Conduction at mounting interface • Low power duty cycle Baffle Door Baffle Door Door Pin Puller Optical Bench Aft Optics Stepper Motors

23. Thermal Control Hardware • Thermistors • Manufacturer: Measurement Specialties • Part # 311P18-06A101 • 5K Ohm resistance @ 25oC • RTD’s • Manufacturer: Goodrich Corp. • Part # 0118MF-2000-A • 2K Ohm resistance • Heaters • Manufacturer: Tayco • Type: TPC-6002 Flexible Kapton • Thermostats • Manufacturer: Honeywell • Type: 701 series bi-metallic/mechanical • MLI • 1 outer Layer: 2.75 mil Germanium Black Kapton (GBK) • 13 middle layers: 0.25 mil Aluminized Mylar (VDA2) • 14 separators: B4A Dacron mesh • 1 inner layer: 2 mil Kapton (VDA1) • Material Vendors: Sheldahl; Dunmore

24. Thermal Control Hardware • Temperature Sensor Specifications • Heater Specifications

25. Thermal Model: Geometric Configuration • Instrument Suite & Payload Interface Platform (PIP) MIGHTI-B Payload Interface Platform (PIP) MIGHTI-A Camera Electronics Box (CEB) Calibration Lamp

26. Thermal Model: Geometric Configuration • MIGHTI Instrument Assembly TEC Radiator Baffle Aft Optics Radiator Supports (1 of 2) Camera Conductor-Heat Pipe to Radiator Optical Bench OB Cover

27. Thermal Model: Geometric Configuration • Camera Electronics Box (CEB) & Calibration Lamp CEB Radiator Calibration Lamp Housing CEB Housing

28. Thermal Model: Giver-Receiver Information Exchange • Thermal Model Format • Autocad 2014; Thermal Desktop/ SindaFluint -Version 5.6 • ATK to SSL • Reduced MIGHTI instrument Assembly • MIGHTI-A; MIGHTI-B; Camera Electronics Box (CEB); Calibration Lamp • Include geometry; optical properties; thermal masses; conduction network; transient dissipations • SSL to ATK • Reduced PIP & Instrument Suite (geometry & optical properties only) • ATK to SDL • Preliminary CEB radiator size • CEB environmental and IR backload heat loads (transient) • SDL to ATK • CEB mechanical configuration & internal power dissipation • TEC hot side temperature vs. power profile

29. Thermal Model: Assumptions • Altitude • Circular 576 km (nominal) • Evaluation of altitude range 450 km to 665 km pending • Vehicle Attitude • Operational: +Z Nadir / +X velocity vector • Beta angle versus Time of Year • Orbits • Beta = 50o • Beta = 0o • Beta = -50o

30. Thermal Model: Assumptions • Optical Properties • Environments

31. Thermal Model: Assumptions • Component Power Dissipations • TEC Power Dissipation

32. Thermal Model: Assumptions • Component Masses (as modeled) • Cal Lamp – 1.5 kg • Baffle – 1.84 kg • Camera Electronics – 2.65 kg • TEC Hot Side – 0.159 kg • Material Properties

33. Thermal Model: Assumptions • Mechanical • Multi-Layer Insulation (MLI) Effective Emittance • Larger blankets: e* = 0.01 to 0.03 • Smaller blankets: e* = 0.03 to 0.10

34. Thermal Analysis: Results Summary • Operational Hot Case

35. Thermal Analysis: Results Summary • Operational Cold Case

36. Thermal Analysis: TEC Dissipation • TEC Hot Case Orbit Average Dissipation • TEC hot side parasitic heat load not included

37. Thermal Model: Analysis Transient Results – TEC Hot Side • Hot – Beta -50° - MIGHTI A/B • Cold – Beta 0° - MIGHTI A Cold – Beta +50° - MIGHTI B

38. Thermal Model: Analysis Transient Results – Radiators • Hot – Beta -50° - MIGHTI-A Hot – Beta -50° - MIGHTI-B • Cold – Beta 0° - MIGHTI-A Cold – Beta +50° - MIGHTI-B

39. Thermal Model: Analysis Transient Results - Baffles • Hot – Beta +50° - MIGHTI-A Hot – Beta +50° - MIGHTI-B • Cold – Beta -50° - MIGHTI-A Cold – Beta -50° - MIGHTI-B

40. Thermal Model: Analysis Transient Results – Electronics • Hot – Beta -50° - Camera Electronics & Calibration Lamp • Cold – Beta +50° - Camera Electronics & Calibration Lamp

41. Trade Studies: Thermal Strap vs. Heat Pipe (1 of 2) • Heat Pipe • Thermal Strap

42. Trade Studies: Thermal Strap vs. Heat Pipe (2 of 2) • Summary of Results • Conclusion • Thermal strap not a viable option • 3 lbm solid K-Core section does not meet requirements for high beta angle conditions • Likely mass required >6 lbm to meet requirements (11 lbm for heat pipe equivalent performance) • Heat pipes meet requirements for worst case on orbit conditions • 2-3 lbm within practical application • Orbit average TEC dissipation reduced relative to strap • Heat pipe cost comparable to strap: ROM approximately $30-50K • Testing considerations/restrictions can be accommodated

43. Testing (1 of 2) • Standards per GEVS GSFC-STD-7000A • Thermal vacuum qualification standards to ensure that the payload operates satisfactorily in a simulated space environment at more severe conditions than expected during the mission. • Component / Unit Level • Typically done by vendor • Applicable to components with power dissipation: camera, CEB, calibration lamp, motors, actuators • 1 survival cycle • Minimum of 8 thermal vacuum operational temperature cycles • Minimum of 4 hours at each extreme of each temperature cycle • Subsystem / Instrument Level • 1 survival cycle • Minimum of 4 operational thermal vacuum temperature cycles • Minimum of 12 hours at each extreme of each temperature cycle • Thermal balance: survival, hot operational, cold operational • Payload/Spacecraft Level • 1 survival cycle • 4 thermal vacuum operational temperature cycles (2 with project approval; dwell times doubled) • Minimum 24 hours at each extreme of each temperature cycle • Thermal balance as practical

44. Testing (2 of 2) • Functional testing • At each operational temperature plateau • Turn on test following recovery from survival plateau (usually combined with functional test) • Test Margins • See notes associated with temperature limits table • Considerations/limitations • Likely auxiliary GSE required for radiator temperature control; instrument & payload/SC level • GN2 / heater controlled panels • Heat pipes must be oriented to perform in “reflux” mode • Evaporator (TEC) must be lower than condenser (radiator) relative to gravity • No limitation for +Z axis vertical • For +Z axis horizontal vehicle must be clocked about Z axis to maintain reflux; approximately 90o rotation window

45. Plan Forward to PDR • Optical Bench Assembly • Includes bench, cover, aft optics, interferometer (no optical components except IF) • Complete high fidelity thermal models • Incorporate interface conductance effects per previous chart • Optimize radiator sizes, locations (NA for interferometer) • Define operational heater layout • Heat Pipe Radiator Assembly • Complete feasibility evaluation incorporating a short thermal strap at TEC/pipe interface • Effort to gain additional mechanical compliance to mitigate camera alignment/distortion issue • Camera • Complete housing radiator design • Determine if housing needs to be thermally coupled to optical bench • Camera Electronics • Good shape for PDR • Calibration Lamp • Refine housing radiator size/location • Other • Clarify all temperature limits • Survival / safe-mode analysis to determine heater requirements • Update PIP geometry to include star tracker radiator blockage effects (likely negligible)