C osmic R Ay T elescope for the E ffects of R adiation Telescope Mechanical Design Albert Lin The Aerospace Corporation Mechanical Engineer (310) /28/05

C osmic R Ay T elescope for the E ffects of R adiation Overview Design Overview Instrument Requirements Mechanical Requirements Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation Design Overview Detectors are housed in stiff structure and decoupled from the interface circuit board TEP mounts allow for thermal expansion/contraction Instrument is shielded and electrically isolated at interface

C osmic R Ay T elescope for the E ffects of R adiation Overall Dimensions Weight = 2.32 lbs

C osmic R Ay T elescope for the E ffects of R adiation Overview Design Overview Instrument Requirements Mechanical Requirements Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation Instrument Requirements From Instrument Requirements Document (IRD) ItemRequirement CRaTER-L2-04TEP components of 27 mm and 54 mm in length CRaTER-L3-01Adjacent pairs of 140 micron and 1000 micron thick Si detectors CRaTER-L3-02Aluminum shielding 0.06” thick CRaTER-L ” thick aluminum on both ends of the telescope CRaTER-L3-04Telescope stack: S1, D1, D2, A1, D3, D4, A2, D5, D6, S2 CRaTER-L3-06Zenith field of view from D1D6 at 35 degrees CRaTER-L3-07Nadir field of view from D3D6 at 75 degrees All requirements incorporated into model

C osmic R Ay T elescope for the E ffects of R adiation Telescope Geometry All Requirements Met A-150 TEP of 27 mm and 54 mm in length Pairs of thin (~140 micron) and thick (~1000 micron) Si detectors used 0.060” nominal aluminum shielding 0.030” thick aluminum on top and bottom apertures Telescope stack consistent with requirement 35 degree FOV Zenith 75 degree FOV Nadir

C osmic R Ay T elescope for the E ffects of R adiation Overview Design Overview Instrument Requirements Mechanical Requirements Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation Mechanical Requirements From 431-RQMT , Mechanical System Specifications Requirement DescriptionLevels Net CG limit loads Superceded by Random Vibration 12 g Sinusoidal Vibration Loads Superceded by Random Vibration Frequency: Hz Protoflight/Qual: 8g Acceptance: 6.4g 2.5 Acoustics Enclosed box without exposed thin surfaces OASPL Protoflight/Qual: dB OASPL Acceptance: dB Random VibrationSee next slide 2.7.2Shock Environment 40 g at 100 Hz 2665 g at Hz No self induced shock Minimum Fundamental FrequencyMinimum > 35 Hz Recommended > 50 Hz Will not provide FEM model > 75 Hz

C osmic R Ay T elescope for the E ffects of R adiation Random Vibration 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 = 15

C osmic R Ay T elescope for the E ffects of R adiation Stress Margins Load levels are superceded by random vibration spec Factors of Safety used for corresponding material (MEV 5.1) –Metals: 1.25 Yield, 1.4 Ultimate –Composite: 1.5 Ultimate Margin of Safety = (Allowable Stress or Load)/(Applied Stress or Load x FS) – 1 DescriptionMS yieldMS ultimate Bolt Interface Loading+7,291+14,709 Interface Circuit Boardbrittle+0.45 Silicon Detectorbrittle+48.3 All components have positive Margin of Safety

C osmic R Ay T elescope for the E ffects of R adiation First Fundamental Frequency First Fundamental Frequency at 2340 Hz

C osmic R Ay T elescope for the E ffects of R adiation Overview Design Overview Instrument Requirements Mechanical Requirements Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation How to Mount TEP Limited Material Properties information on A-150 TEP Need to mount TEP to –Minimize deformation of TEP during assembly –Allow for thermal contraction –Exert 20 lbs preload to withstand random vibration Springs exert 20 lbs at hot and cold cases Detectors TEP Sample Solution Oversized mounting hole to allow for changes in radial dimension Spring clamp to hold in TEP with preload at all temperatures

C osmic R Ay T elescope for the E ffects of R adiation Mounting Details, Purging and Venting Detectors mounted using #2-56 fasteners Pigtail connector feeds through hole and plugs into the Analog board in the E-box Spacers between each pair of detectors for venting No enclosed cavities Internal purge line from Ebox connects to telescope purge system (not shown) –Detailed design of purge system pending Connection

C osmic R Ay T elescope for the E ffects of R adiation Overview Design Overview Telescope Requirements Mechanical Requirements Design Details Next Steps

C osmic R Ay T elescope for the E ffects of R adiation Next Steps Finalize interface between telescope assembly and electronics box Detail purge design Complete drawings for fabrication

C osmic R Ay T elescope for the E ffects of R adiation

Backup Slides

C osmic R Ay T elescope for the E ffects of R adiation CRaTER-L Requirement Break the TEP into two components, of 27 mm and 54 mm in length.

C osmic R Ay T elescope for the E ffects of R adiation 6.1 CRaTER-L3-01Thin and thick detector pairs Requirement The telescope stack will contain adjacent pairs of thin (approximately 140 micron) and thick (approximately 1000 micron) Si detectors. The thick detectors will be used to characterize energy deposition between approximately 200 keV and 100 MeV. The thin detectors will be used to characterize energy deposits between 2 MeV and 1 GeV. 6.2 CRaTER-L3-02 Nominal instrument shielding Requirement The shielding due to mechanical housing the CRaTER telescope outside of the zenith and nadir fields of view shall be no less than 0.06” of aluminum.

C osmic R Ay T elescope for the E ffects of R adiation 6.3 CRaTER-L3-03 Nadir and zenith field of view shielding Requirement The zenith and nadir sides of the telescope shall have no less than 0.03” of aluminum shielding. 6.4 CRaTER-L3-04 Telescope stack Requirement The telescope will consist of a stack of components labeled from the nadir side as zenith shield (S1), the first pair of thin (D1) and thick (D2) detectors, the first TEP absorber (A1), the second pair of thin (D3) and thick (D4) detectors, the second TEP absorber (A2), the third pair of thin (D5) and thick (D6) detectors, and the final nadir shield (S2).

C osmic R Ay T elescope for the E ffects of R adiation 6.6 CRaTER-L3-06 Zenith field of view Requirement The zenith field of view, defined as D1D6 coincident events incident from deep space, will be 35 degrees full width. 6.7 CRaTER-L3-07 Nadir field of view Requirement The nadir field of view, defined as D3D6 coincident events incident from the lunar surface, will be 75 degrees full width.

C osmic R Ay T elescope for the E ffects of R adiation Bolt Interface Loading Mechanical Engineering Design, by Shigley RP-1228 NASA Fastener Design First fundamental frequency at 2340 Hz, which is off of the random vibe data set Assume worst-case loading at 2000 Hz 3 sigma load = 105g A286 CRES Bolts at Interface Worst Case Bolt

C osmic R Ay T elescope for the E ffects of R adiation Interface Circuit Board Board Resonance First Mode: 632 Hz Total nodes:25225 Total elements:12901 COSMOSWorks 2005

C osmic R Ay T elescope for the E ffects of R adiation Detector Board Stress Using Miles Equation, assume Q = 15, FS = 1.5 3σ g loading = 146 g Material = Polyimide-Glass Max Stress = 3,663 psi MS ultimate = 24,000 psi / (1.5 * 3* 3,663 psi) - 1 = 0.45

C osmic R Ay T elescope for the E ffects of R adiation Detector Analysis Assuming Q = 15 Detector Material = Silicon Fundamental Frequency = 2130 Hz; 2000 Hz yields 3 sigma load of 105g Ultimate Margin of Safety = (17,400 psi / (1.4 * 252 psi) – 1 = 48.3

C osmic R Ay T elescope for the E ffects of R adiation Sensitivity Analysis Preceding calculations used a nominal Q of 15 This table shows how the 3 sigma g-loads vary with Fundamental Frequency and Q Most structures have Q between 10 and 20

C osmic R Ay T elescope for the E ffects of R adiation Factors of Safety Used

C osmic R Ay T elescope for the E ffects of R adiation Material Properties 1.MIL-HDBK-5J 2.Silicon as a Mechanical Material, Proceedings of the IEEE, Vol 70, No. 5, May 1982, pp