C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design1 Albert Lin The Aerospace Corporation (310) /27/06

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design2 Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design3 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 isolated at interface. Purge runs through channels machined into housing.

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design4 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.

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design5 Peer Review Summary 1.Telescope design requires close machining tolerances for success. Action: Modified design to increase robustness. 2.Detectors are not specified for random vibration and shock seen at the interface mount. Action: Plan to test engineering model detectors mounted in assembly. 3.Thin electrical isolation material specified at PDR may be too thin. Action: Use.063” G-10 sheet for isolation. 4.Purge channel cover screws may not be EMI tight. Action: None at this time. Add more screws if EMI emissions are too high. 5.Detectors will give poor measurements if there is light leakage. Action: Working to specify light tight requirements. 6.Force requirements for TEP preload is not toleranced. Action: Added tolerances to spring requirements.

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design6 Overall Dimensions and Weight Component Weight (kg) Weight (lbs) Structure Circuit Board Telescope Total

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design7 Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design8 Instrument Requirements – Level 2 From Instrument Requirements Document (IRD) CRaTER- L2-03 Minimum path length through the total amount of TEP in the telescope shall be at least 60 mm. CRaTER- L2-04 TEP components of 27 mm and 54 mm in length

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design9 Instrument Requirements – Level 3 From Instrument Requirements Document (IRD) CRaTER-L3-01 Adjacent pairs of 140 micron and 1000 micron thick Si detectors CRaTER-L3-03 Nominal instrument shielding 1524 micron (0.060”) thick aluminum or equivalent CRaTER-L3-04 No more than 762 micron (0.030”) thick aluminum on zenith and nadir fields of view

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design10 Instrument Requirements – Level 3 From Instrument Requirements Document (IRD) CRaTER- L3-05 Telescope stack: S1, D1, D2, A1, D3, D4, A2, D5, D6, S2, where: S1, S2 are the zenith and nadir shields, respectively D1, D3, D5 are thin silicon detectors D2, D4, D6 are thick silicon detectors A1, A2 are TEP specimens CRaTER- L3-07 Zenith field of view from D2 to D5 shall be less than 34° CRaTER- L3-08 Nadir field of view from D4 to D5 shall be less than 70° Nadir Zenith

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design11 Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design12 Mechanical Requirements From 431-RQMT , Mechanical System Specifications SectionDescriptionLevelsVerification Net cg limit load28.9 g*Analysis Sinusoidal Vibration Loads Protoflight; Frequency (Hz) Level cm D.A – 50 8 g’s Analysis, Test 3.1.5AcousticsDelta IV Medium: dB Atlas V 401: dB Test at LRO level Random VibrationSee Random Vibration slideAnalysis, Test 3.1.7Shock environmentSee Shock Environment slideTest at LRO level 3.1.8VentingMinimum of.25 in 2 of vent area per cubic foot volume Analysis * Interpolated from Table 3-1 for CRaTER at 6.4 kg.

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design13 Random Vibration Levels Frequency (Hz) Protoflight /Qual (g 2 /Hz) Acceptance (g 2 /Hz) Overall 14.1 g rms 10.0 g rms Random Vibration levels will drive the analysis.

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design14 Updated Shock Environment FrequencyLevel (Q=10) 100 Hz 20 g 800 Hz930 g 10,000 Hz930 g

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design15 Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design16 Frequencies and Mass Participations Frequency (Hz) Mass ParticipationWhere Shield 1, Large TEP Assy 1, Housing 1, Circuit Board 1, Small TEP Assy

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design17 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 g Assume Q = 40 for worst case Frequency (Hz) Protoflight/ Qual (g 2 /Hz) Acceptance (g 2 /Hz)

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design18 Random Vibration Loads Factors of Safety used for corresponding material (MEV 5.1) –Metals: 1.25 Yield, 1.4 Ultimate –Composite: 1.5 Ultimate Assume Q=40 Freq (Hz)3σ load (g)Stress (psi)MS yield MS ult Telescope Housing1, , Detector2, Shield , Circuit Board1, , TEP1, σ load (g) Worst Normal/Shear (lbs) MS yield MS ult Interface Bolts19453 /

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design19 Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design20 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 Cable and connector 4 mounting holes

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design21 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

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design22 TEP Material Properties TEPDelrin Density1,110 kg/m 3 1,411 kg/m 3 Tensile Modulus1,958 MPa3,100 MPa Tensile Yield 20 ºC 14.4 MPa89.6 MPa Compression 20 ºC 58.6 MPa110 MPa CTE (20 ºC to –30 ºC)18.9 μm/m-ºC84.6 μm/m-ºC 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.

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design23 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

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design24 Overview Design Overview Instrument Requirements Mechanical Requirements Analysis Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design25 Next Steps Finalize MLI attachment near telescope Submit flight drawings for fabrication Make assembly drawings

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design26 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

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design27 Telescope – Mechanical Albert Lin

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design28 Material Properties 1.MIL-HDBK-5J 2.Silicon as a Mechanical Material, Proceedings of the IEEE, Vol 70, No. 5, May 1982, pp Plastics, Edition 8, Ultimate Tensile from Electronic Materials and Properties 4.Boedeker Plastics via

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design29 Bolt Interface Analysis

C osmic R Ay T elescope for the E ffects of R adiation 6/27/06 Telescope Mechanical Design30 Bolt Interface Loading Mechanical Engineering Design, by Shigley RP-1228 NASA Fastener Design First fundamental frequency at 1564 Hz 3 sigma load = 194g A286 CRES #6-32 Bolts at Interface