Matthew Smith (617)-252-1736 matt@space.mit.edu June 27, 2006 Mechanical Design, CRaTER Assembly and Electronics Assembly Critical Design Review Matthew Smith (617)-252-1736 matt@space.mit.edu June 27, 2006 9/21/2018

Overview Assembly Description Mechanical Design Details Mechanical Environments and Requirements Near Term Tasks Back-up slides 9/21/2018

Assembly Description Crater integrates two main sub-assemblies: The Telescope Assembly and The Electronics Assembly. The Telescope Assembly is being designed and built by The Aerospace Corporation The Analog Board is being designed by Aerospace. The Flight Analog Boards will be built by MIT The Digital Board and Electronics Enclosure Assembly are being designed and built by MIT. MIT will integrate the two sub-assemblies and perform all functional, environmental and acceptance testing. L13.5”x W9” x H 6” Weight 6.4Kgs max. 9/21/2018

Assembly Description 32-10204 32-10201 32-10206 32-10203 32-10202 32-10205 9/21/2018

Overview Assembly Description Mechanical Design Details Mechanical Environments and Requirements Near Term Tasks Back-up slides 9/21/2018

Natural Frequencies We put the CRaTER mock up unit on a shake table Friday June 23, 2006. We had accelerometers on the analog and digital boards(2 single axis accels), the two covers, the telescope(2 triax accels) and on the e-box(one triax and one single axis). 9/21/2018

Natural Frequencies Natural Frequency Estimates From SOLID WORKS cosmos package, 2005 CRaTER as an assembly First frequency at 435Hz (top cover) Dominant Frequency at 1158 Hz and 1516 Hz (main assembly) Analog Board- 648 Hz Digital Board- 497 Hz Top Cover- 435 Hz Bottom Cover – TBD (hidden in model for now) From SOLID WORKS cosmos package, 2005, stand alone parts. Analog Board- 195 Hz Digital Board- 198 Hz Top Cover- 288 Hz Bottom Cover - 337 Hz E-Box - 992 Hz 9/21/2018

Natural Frequencies Natural Frequency from Low level sine sweep, June 23, 2006 CRaTER as an assembly Z Axis (Normal to mounting surface) First frequency at ~ 280Hz (Bottom cover) Dominant Frequency at ~1200 and 1500 Hz (main assembly) Analog Board ~700 Hz Digital Board ~410 Hz Top Cover ~410 Hz Bottom Cover ~280 Hz CRaTER as an assembly X Axis First frequency at ~ 980 Hz Second at ~1500 Hz Crater as an assembly, Y Axis First frequency at ~ 1200 Hz These match very closely to the Solidworks Model as an assembly. First frequency at 435Hz (top cover) First Frequency of the system at 1158 Hz (main assembly) Analog Board- 648 Hz Digital Board- 497 Hz Top Cover- 435 Hz Bottom Cover – TBD (hidden in model for now) 9/21/2018

Natural Frequencies Discussion Discussion of the differences in the frequency analysis: The method used for the CRaTER assembly frequency analysis is based on the contact surfaces (such as the boards to e-box, covers to e-box and telescope to e-box) as having a bonded interface, which is slightly unrealistic but yields a boundary condition for frequency analysis. The method used for the individual analysis puts a boundary condition on either the edges of the part or their mounting holes. 9/21/2018

Material Properties 9/21/2018

Stress Margins Results Load levels are dominated by random vibration spec. For resonances in the Random Vibration Spec, Miles’ Equation shows 3 sigma loading on the order of 94-228 g Q varies from 20-33. Factors of Safety, FS, used for corresponding material (MEV 5.1) Metals: 1.25 Yield, 1.4 Ultimate Composite: 1.5 Ultimate * Margin of Safety (MOS)= (Allowable Stress or Load)/(Applied Stress or Load x FS)-1 9/21/2018

CRaTER Assembly Stresses Dominant Frequency is 1516 Hz Using Miles Equation, Q=20 3 sigma g loading= 154 g Max Stress is 21,400 psi MOS Y= 1.7 MOS U= 1.8 9/21/2018

Analog Board Resonance First Mode 195 Hz Dim: 5.95” x 8.43” x .10” mass~.75 lbs graph shows displacement 9/21/2018

Analog Board Stresses Using Miles Equation Assume Q=20, 3 sigma g loading= 93.9g Max Stress is 15,212 psi MOS Ult= 1.2 9/21/2018

Digital Board Resonance First frequency is 198 Hz. Dim: 8.66” x 7.55” x .093” Mass ~.80 lbs Graph is showing displacement 9/21/2018

Digital Board Stresses Using Miles Equation Assume Q=20, 3 sigma g loading= 94.6 g Max Stress is 11,203 psi MOS Ult= 2.0 9/21/2018

Top Cover Resonance First Mode 288 Hz Dim: 9.35” x 6.94” x .16” mass = .43 lbs 9/21/2018

Top Cover Stresses Using Miles Equation, Assume Q=33, 3 sigma g loading=106 g Material is aluminum Max Stress is 4246 psi MOS Y= 9.4 MOS U= 9.9 9/21/2018

Bottom Cover Frequency First frequency is 337 Hz. Dim: 8.4” x 9.1” x .21” Mass =.53 lbs 9/21/2018

Bottom Cover Stresses Using Miles Equation, Assume Q=33, 3 sigma g loading= 158.6 g Max Stress is 28.7 kpsi MOS Y= 0.5 MOS U= 0.6 9/21/2018

DESIGN DETAILS Stress Margins, Hardware Load levels are driven by random vibration spec Factors of Safety used for corresponding material from 431-SPEC-000012. Metals: 1.25 Yield, 1.4 Ultimate Margin of Safety = (Allowable Stress or Load)/(Applied Stress or Load x FS) – 1 Description Location/ # of bolts Material Desc. MS Yield MS Ultimate Comments #4-40 SHCS Analog Board/30 CRES, A 286 > +14.2 > +19.5 4 Bolts used in the analysis # 4-40 SHCS Digital Board/35 > +13.4 > +18.4 8 Bolts used in the analysis Top Cover/37 > +447 > +597 #2-56 SHCS Bottom Cover/32 > +24.6 > +32.8 #10-32 SHCS Mounting Feet/6 +2.8 +3.1 6 Bolts used in the analysis 9/21/2018

Overview Assembly Description Mechanical Design Details -peer review summary Mechanical Environments and Requirements Near Term Tasks Back-up slides 9/21/2018

Significant Peer Review Comments Observation: The CRaTER design team should use its finite element model to determine what the expected bolt loads are and provide this information to the host spacecraft to verify that the individual bolt loads are acceptable. CRaTER Group Response: In process of determining loads and will add to the MID. The electronics structure is very stiff in the vertical direction at the six mounting feet. The flatness of the mounting surface is specified to be flat to within 0.005”. When the housing is mounted to a very stiff surface (such as a shake fixture) the feet will be displaced causing stresses within the housing to develop. If the force required to get contact at each foot exceeds the tension in the mounting screw there will be a gap between the bottom of the foot and the mounting surface. In process of determining loads and factors of safety. The printed circuit boards are presently listed as being stress limited due to highly localized stresses at the mounting holes. Either the fidelity of the modeling has to be increased to show that the stress concentrations are not as severe as presently shown or the mounting configuration has to be modified to make for more robust PCB mounting. 9/21/2018

Significant Peer Review Comments Observation: The shock test levels specified in the Mechanical Systems Specification (431-SPEC-000012) apply at the payload adaptor fitting (Table 3-12) and the Deployable Interface (Table 3-11), not at the CRaTER mounting location. The levels as given are very high and may pose a significant challenge to the CRaTER instrument, particularly the detectors. Presently there are no plans to subject the instrument to shock testing prior to the testing that will be performed after integration with the host spacecraft. Crater Group Response We are working with the space craft group to specify a more viable shock spec. The detectors are sensitive to visible light as well as the cosmic ray radiation that they are intended to measure. A specification on how much visible light attenuation should be specified. The test program should include a test to verify the integrity of the light sealing. In process of determining acceptable levels. 9/21/2018

Other Peer Review Comments Observation: The CRaTER instrument has provisions to periodically purge the interior of the instrument during storage and integration activities. Presently there are no filters on the inlet or outlet ends of the purge path. CRaTER Group Response A 316 SS, 2 micron filter will be added on the exit side of the purge system. A GSE filter will be placed in the fore line of the purge fitting and removed at installation to the space craft. The CRaTER instrument’s purge gas will be supplied by a supply line on the spacecraft that will also be supplying other instruments. Proper proportioning of the supply gas to the various instruments requires control of the back pressure and supply pressure to create the desired flow rates. This issue is not covered by the interface control document. CRaTER Group Response: We have determined a flow rate and will add it to the MID. The host spacecraft will supply electrical power for and control of a survival heater for the CRaTER payload. At this point in time there is no decision on where the heater will be located (on the S/C panel or within the CRaTER assembly) nor the power dissipation required. CRaTER has allocated space and wiring for the heater on the internal part of the Electronics Housing. 9/21/2018

CURRENT BEST ESTIMATE, MASS PROPERTIES Electronics Assembly grams lbs Analog CCA 340 0.75 Digital CCA 453 1.00 DC/DC converters and EMI filter 100 0.22 Interconnect Cable, A/D 91 0.20 Internal E-box wire, heater, Thermostats, connectors 227 .50 Mechanical Enclosure 1948 4.30 Top Cover 195 0.43 Connector access cover 32 0.07 Bottom Cover 240 0.53 Internal Hardware 163 0.36 Purge system 113 0.25 Electronics Assembly Sub-Total 3900 8.61 Telescope Assembly Sub- Total 1273 2.81 MLI and TPS Sub-Total 249 .55 Mounting Hardware Sub-Total 41 .09 CRaTER CBE Total 5463 12.06 9/21/2018

Overview Assembly Description Mechanical Design Details Mechanical Environments and Requirements (Changes from PDR) Near Term Tasks Back-up slides 9/21/2018

Mechanical Environments - Imposed From 431-RQMT-000012, Rev A, Environments Section 3.1. Section Description Levels 3.1.1.2 Net cg limit load 28.9 g*1 3.1.4.2 Sinusoidal Vibration Loads Protoflight; Frequency (Hz) Level 5 - 17.7 1.27cm D.A. 17.7 – 50 8 g’s 3.1.5 Acoustics Delta IV Medium: Protoflight OASPL 140.0 dB Atlas V 401: Protoflight OASPL: 137.0 dB 3.1.6.1 Random Vibration See Random Vibration slide 3.1.7 Shock environment See Shock Environment slide 3.1.8 Venting Minimum of .25 in^2 of vent area per cubic foot volume 1 Interpolated from Table 3-1 for CRaTER at 6.4Kgs. Red colors indicated changes from PDR 9/21/2018

Updated Shock Environment Frequency Level (Q=10) 100 Hz 20 g 800 Hz 930 g 10,000 Hz 9/21/2018

Mechanical Environments, Imposed Shock Environment Table 3-12 LRO/PAF Shock Response Spectrum Delta IV (1194 PAF) Atlas (Type B1194 PAF) Frequency (Hz) Level (Q=10) 100 100-1,000 1,000-10,000 150 g +9.2 dB/Octave 5,000 g 100-1,400 1,00-10,000 100 g +7.6 dB/Octave 2,800 g Table 3-13 Deployable Separation Mechanism Shock Response Spectrum Separation Nut (SN9423-2) Frequency (Hz) Level (Q=10) 100 100-3,000 3,000-10,000 50 g +7.8 dB/Octave 4,000 g 9/21/2018

Overview Assembly Description Mechanical Environments and Requirements Mechanical Design Details Near Term Tasks Back-up slides 9/21/2018

NEAR TERM TASKS FROM PDR Update MICD to reflect latest configuration. Released the MICD. Further develop analysis on natural frequencies and stresses using SOLID WORKS and COSMOS on the complete CRaTER Assembly. Continuing to work on all natural frequency and stress analysis. Finalize interface between Telescope Assembly and Electronics Box Assembly. Specify the electrical isolation material between the telescope and the E-Box. Identify the GN2 purge system (mechanical interface to the spacecraft, internal flow, pressure measurements…) Completed the design of purge system. Complete the drawings for part and assembly fabrication. Completed the fabrication drawings for the engineering unit. Assembly drawings are in process. Define attachment points and outline for thermal blankets. To be completed after Engineering unit is finished. 9/21/2018

NEAR TERM TASKS-Post CDR Low level sine sweep analysis of the Engineering Unit mock up. Close out peer review comments. Finish assembly of the Engineering Unit. Complete the drawings for fabricated Flight parts and Flight assembly drawings. Release of the Flight Electronics Box Housing drawing and purchase order by July 17, 2006. Vibration testing of Engineering Unit. Generate procedures for Vibe tests. Define attachment points and outline for thermal blankets. 9/21/2018

Backup Slides 9/21/2018

Mechanical Environments, Imposed Random Vibration Random Vibration Levels 9/21/2018

Mechanical Requirements - Imposed Test Factors Table 3-16 Test Protoflight Comments Structural Loads Level Duration Centrifuge Sine Burst 1.25 x Limit Load 30 seconds 5 Cycles Full Level Acoustic Limit Level +3 dB 1 minute Will be tested at LRO Level Random Vibration 1 minute per axis Sine Vibration Sweep Rate 1.25 x Limit Level 4 Octave/Minute per Axis Shock Actual Device Simulated 2 Actuations 1.4 x Limit Level 1 Actuation/Axis 9/21/2018

Mechanical Requirements and Verification From 431-RQMT-000012, Rev A, Verification Requirements Section 3.3. Section Description Levels/Comments 3.3.1 Factors of Safety See FOS table 3.3.2 Test factors See Test Factors table 3.3.3.2 Perform frequency verification test for Instruments with frequencies above 50 Hz.. Verify and report frequencies up to 200Hz Low level sine sweep 3.4 Finite Element Model requirements: Instruments with predicted first frequencies below 75 Hz shall provide Finite Element Models. CRaTERs first fundamental frequency is well above 75Hz. 9/21/2018

Mechanical Requirements and Verification From 431-RQMT-000012, Rev A, Frequency Requirements Section 3.2. Section Description Levels 3.2.2.1 Fundamental frequency, Hz > 35 Hz 9/21/2018

Mechanical Requirements- Imposed Factors of Safety These are applied to the Protoflight level testing 9/21/2018

General Thermal Subsystem Requirements from 431-Spec-000091 Section Description 4.1 Exterior facing MLI blankets shall have 3 mil Kapton with VDA in outer Coating. 4.2 MLI Blanket Grounding: All blankets shall be grounded per 431-ICD-00018 4.3 MLI Blanket Documentation: The location and shape documented in as-built ICDs. 4.4 Attachment to MLI Blankets: All exterior MLI blankets shall be mechanically constrained at least at one point. 9/21/2018

Mechanical Requirements and Verification Summary We also meet all of our internal requirements: Have adequate contact area (.5 in^2 min) to the spacecraft to support Thermal requirements. (min is .51 in^2) Provide safe structure, within Factors of Safety specified, to support Telescope Assembly. Provide for mounting 2 Circuit Card Assemblies. The Analog Board and Digital Board must be separated by an aluminum plate. Provide means to route cable from telescope to the Analog side of the Electronics Enclosure with minimizing noise. Electrically isolate the Electronics Enclosure from the Telescope, yet provide sufficient thermal conductance path. Electrical Interface to the Spacecraft to be on one side of the Electronics Enclosure. The interface connectors to be on the Digital side of the Electronics Enclosure (separate from the Analog side) Provide GN2 purge interface inlet and outlet ports. Follow the octave rule for natural frequency of the PWAs to the Electronics Enclosure. 9/21/2018

Engineering Unit Drawing List Drawing Number Drawing Title Rev. Layout Complete Drawing Created Checked Released 32-20000 CRaTER Assembly 90% 32-20200 Electronics Assembly   32-20201 Digital Electronics, PWA √ 75%  32-20201.0101 Digital Electronics, PWB 32-20201.01 Digital Electronics, Outline Dwg. B  √ 32-20202.01 Analog Electronics, Outline Dwg. A 32-20203 Electronics Enclosure 32-20204 Cover, Top 01   √ 32-20205 Cover, Bottom 32-20206 Cover, Access 32-20208 Cable, Interconnect D/A 9/21/2018

Electronics Box Housing Resonance First Mode 992 Hz Dim: 9.40” x 9.06” x 6.15” mass= 4.04 lbs graph shows displacement 9/21/2018