NuSTAR Critical Design Review Ae 105 June 3, 2008 California Institute of Technology

1. NuSTAR Critical Design ReviewAe 105June 3, 2008California Institute of Technology Structural/Thermal ElahBozorg-Grayeli Elliott Pallett Matt Wierman ZacLizer AlirezaMoammadKarim Francisco Montero Chacon VaheGabuchian Dynamics/Control Silas Hilliard In KiChoi PrakharMehrotra Kevin Watts Derek Chan Metrology Nick Boechler Jason Damazo Manuel Fuentes David Gutschick 1

2. Project Introduction • Project conducted as part of an 8 week interactive JPL-Caltech course • Performed analysis on multiple aspects of JPL flight project: NuSTAR 2

3. NuSTAR Mission Overview • X-Ray Observatory • Obtain higher resolution images of x-ray sources • Two hard x-ray optics with 10 m focal lengths • 24 month mission (2) X-Ray Mirrors Mast & Canister (2) Focal Plane Modules Spacecraft Bus 3

4. NuSTAR Description (2) X-Ray Mirrors S/C Bus 10.9 m Extendible Boom 4

5. Chief Concern • X-Ray optics require precise pointing and alignment • Mirrors are mounted on end of extensible boom • Required accuracy of optics mandate determination of boom behavior 5

6. JPL Level 1 Requirements 6

7. Ae 105 Project Goals • Analyze the performance of NuSTAR observatory • Conduct structural and thermal analysis of the boom • Predict attitude and dynamics of the S/C • Design a metrology system to determine the position and orientation of the mirrors with respect to the bus • Assure JPL level 1 and below requirements are met 7

8. Project Structure 8

9. Structural/Thermal • Goal: • Generate integrated structural/thermal model of boom • Translate disturbances/forces into deflections/frequencies • Input: disturbance forces estimated by dynamics • Output: modal analysis results to dynamics and metrology 9

10. Dynamics • Goal: • Generate S/C orbital/ADCS model • Input: Frequencies from structures • Output: forces to structures 10

11. Metrology • Goal: • Design and select a mirror measurement system • Generate model to translate between measurements and real position/orientation • Input: frequencies from structures • Output: metrology system 11

12. Introduction • Objectives • Pre-PDR • Requests for Action • Post-PDR • Boom Description • CALFEM/ANSYS Verification • Cases (1-4) • Thermal Analysis • Deliverables • Conclusions 13

13. Structural/Thermal Objectives • Goal: • Create a FEM model of the NuSTAR boom. • Determine static loading cases • Perform modal analysis on the model to determine natural frequencies. • Create an FD thermal model of the NuSTAR boom • Model shall be capable of determining temperatures based on loading conditions • Integrate structural and thermal models into one package. 14

14. JPL Level 1 Requirements 15

15. Pre-PDR • Populated material properties list • Developed static loading case CALFEM model • Completed analytic thermal model • Wrote thermal FD code for worst case scenario 16

16. Requests for Action • Consider the pre-stress of the cables in the deployed boom. Accepted • Standardize material properties for all boom models. Accepted • Define thermal distortions for more standard loading cases. Accepted • Consider various CTEs of thermal coatings. Accepted • Take into account the joints when modeling thermal distortion. Accepted • Consider how change of truss orientation effects calculations of thermal loading. Accepted 17

17. Post-PDR • Standardized material properties in all models • Created ANSYS model of boom • Verified static analysis of ANSYS with CALFEM • Verified modal analysis of ANSYS with CALFEM • Completed thermal FD code for any S/C orientation 18

18. Boom Description 19

19. CALFEM/ANSYS Verification • CALFEM – less capable, more open • ANSYS – more capable, less open • CALFEM will be used to verify results from ANSYS to establish ANSYS as a proper modeling package 20

20. Case Types 21

21. Case #1 22

22. Case #1: CALFEM - Bending 23

23. Case #1: ANSYS - Bending 24

24. Case #1: Axial Mode 25

25. Case #1: Torsion 26

26. Case #1: Comparisons • Conclusion- CALFEM and ANSYS are internally consistent 27

27. Case #2 28

28. Case #2: CALFEM - Bending 29

29. Case #2: ANSYS - Bending 30

30. Case #2: Axial Mode 31

31. Case #2: Torsion 32

32. Case #2: Comparisons • Conclusion- CALFEM and ANSYS are internally consistent 33

33. Case #3 34

34. Case #3: CALFEM - Bending 35

35. Case #3: ANSYS - Bending 36

36. Case #3: Axial Mode 37

37. Case #3: CALFEM - Torsion 38

38. Case #3: Comparisons • Conclusion- CALFEM and ANSYS are internally consistent 39

39. CALFEM/ANSYS Verification • ANSYS is verified as a modeling package for the NuSTAR boom • Based on results under multiple scenarios using CALFEM and ANSYS • CALFEM – less capable, more open • ANSYS – more capable, less open 40

40. Case #4: ANSYS Modal Analysis 41

41. Case #4: ANSYS - Bending 42

42. Case #4: ANSYS - Elongation 43

43. Case #4: ANSYS - Torsion 44

44. Case #4: Modes 45

45. Thermal • Assumptions • Isothermal members • No conduction between members or joints • Radiative coupling between members • Tilted at 10o away from Sun • All material properties measured at 298.15 K. • CTE-Al = 24 ppm/K • CTE-C = -1 ppm/K • Orbital period = 5700 s • Earth albedo = 0.3 • S/C coating • Absorptivity = 0.17 • Emissivity = 0.83 46

46. Thermal Red - Insolated Black - Shaded 47

47. Thermal 48

48. Thermal • Assuming calibration at 298 K • Sunside: ∆x = 903 μm • Shadeside: ∆x = 861 μm • Across Boom ∆x = 42.6 μm ∆Θ = 182.6 μrad 49

49. Structural/Thermal Deliverables • To Dynamics • Moment of Inertia matrix • Stiffness matrix • Calculated natural frequencies • To Metrology • Deflections • Calculated natural frequencies • To JPL • CALFEM and ANSYS models of boom • ANSYS verified through CALFEM modeling • FD model of thermal loading of the boom • 3D Modal Mass matrix calculator for CALFEM library 50

50. Conclusion • ANSYS is a verified static and modal analysis software • Have created a more robust thermal and structural model of S/C flight conditions • Spacecraft meets level 1 structural/thermal requirements 51