Telescope Mechanical Design

1. Telescope Mechanical Design Albert Lin The Aerospace Corporation (310) 336-1023 albert.y.lin@aero.org 6/27/06 Telescope Mechanical Design

2. Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps Telescope Mechanical Design

3. Design Overview • 3 pairs of thin/thick detectors mounted in rigid structure. • TEP mounts allow for thermal expansion and contraction. • Instrument is shielded and electrically isolatedat interface. • Purge runs through channels machined into housing. Telescope Mechanical Design

4. Activities since PDR Programmatic • Completed Peer Review. • Fabricated engineering model. • Completed part drawings. Design • Isolated detectors mechanically from TEP mounts. • Added G-10 gasket interface to electrically isolate telescope. • Purge system added. • Performed mechanical properties testing on TEP. Telescope Mechanical Design

5. Peer Review Summary • Telescope design requires close machining tolerances for success.Action: Modified design to increase robustness. • Detectors are not specified for random vibration and shock seen at the interface mount.Action: Plan to test engineering model detectors mounted in assembly. • Thin electrical isolation material specified at PDR may be too thin.Action: Use .063” G-10 sheet for isolation. • Purge channel cover screws may not be EMI tight.Action: None at this time. Add more screws if EMI emissions are too high. • Detectors will give poor measurements if there is light leakage. Action: Working to specify light tight requirements. • Force requirements for TEP preload is not toleranced.Action: Added tolerances to spring requirements. Telescope Mechanical Design

6. Overall Dimensions and Weight Telescope Mechanical Design

7. Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps Telescope Mechanical Design

8. Instrument Requirements – Level 2 From Instrument Requirements Document (IRD) 32-01205 Telescope Mechanical Design

9. Instrument Requirements – Level 3 From Instrument Requirements Document (IRD) 32-01205 Telescope Mechanical Design

10. Instrument Requirements – Level 3 Nadir From Instrument Requirements Document (IRD) 32-01205 Zenith Telescope Mechanical Design

11. Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps Telescope Mechanical Design

12. Mechanical Requirements • From 431-RQMT-000012, Mechanical System Specifications * Interpolated from Table 3-1 for CRaTER at 6.4 kg. Telescope Mechanical Design

13. Random Vibration Levels Random Vibration levels will drive the analysis. Telescope Mechanical Design

14. Updated Shock Environment Telescope Mechanical Design

15. Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps Telescope Mechanical Design

16. Frequencies and Mass Participations Telescope Mechanical Design

17. Random Vibration Loads • Random Vibration will drive most of the analysis • For resonances in the Random Vibration Spec, Miles’ Equation shows 3 sigma loading on the order of 150-255 g • Assume Q = 40 for worst case Telescope Mechanical Design

18. Random Vibration Loads • Factors of Safety used for corresponding material (MEV 5.1) • Metals: 1.25 Yield, 1.4 Ultimate • Composite: 1.5 Ultimate Telescope Mechanical Design

19. Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps Telescope Mechanical Design

20. Detector Details • 39 mm flat-to-flat Silicon detectors mounted on FR4 mounts • 140 micron and 1000 micron thick both bond to the same mount design • Micron Semiconductor Limited • Lancing Sussex, UK 4 mounting holes Cable and connector Telescope Mechanical Design

21. How the TEP is mounted • TEP mounted in conical seats to prevent misalignment. • Spring design allows for thermal expansion and contraction • Large TEP is clamped into holder with 267 N (60 lbs) preload using 4 springs • Estimated maximum load is 207 g’s during random vibration • Springs nominally secure TEP up to 400 g’s • Springs that exert > 52 N (11.6 lbs) will secure TEP with a 1.5 factor of safety Telescope Mechanical Design

22. TEP Material Properties • TEP is resilient to clamping with 75.1 MS. • TEP interface will shrink 0.08 mm as it cools from 20ºC to –30ºC. • The spring will make up this difference at –30ºC and still exert preload 258 N (58 lbs) preload. Telescope Mechanical Design

23. Purging and Venting • Spacers between each pair of detectors for venting • No enclosed cavities • Purge/vent system shown in red • Internal purge line from Ebox connects to telescope purge system Telescope Mechanical Design

24. Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps Telescope Mechanical Design

25. Next Steps • Finalize MLI attachment near telescope • Submit flight drawings for fabrication • Make assembly drawings Telescope Mechanical Design

26. Summary • Design changes since PDR • Modified detector mounting scheme • Added vent/purge path • Added electrical isolation between telescope from Ebox • Peer review successfully completed • Further analysis performed • Tested TEP material properties • Engineering model completed • Flight drawings ready to be submitted Telescope Mechanical Design

27. Telescope – Mechanical Albert Lin Telescope Mechanical Design

28. Material Properties • MIL-HDBK-5J • Silicon as a Mechanical Material, Proceedings of the IEEE, Vol 70, No. 5, May 1982, pp 420-457 • Plastics, Edition 8, Ultimate Tensile from Electronic Materials and Properties • Boedeker Plastics via www.matweb.com 1 1 2 3 4 Telescope Mechanical Design

29. Bolt Interface Analysis Telescope Mechanical Design

30. Bolt Interface Loading First fundamental frequency at 1564 Hz 3 sigma load = 194g A286 CRES #6-32 Bolts at Interface Mechanical Engineering Design, byShigley RP-1228 NASA Fastener Design Telescope Mechanical Design