lat-pr-01278 section 22-1 glast lat projectmechanical design integration peer review, march 2003...

LAT-PR-01278 Section 2 2-1

GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003


2. System Engineering2. System Engineering


2. System Engineering2. System Engineering

24 March 2003 rev 3

Martin Nordby [email protected] Nordby [email protected]


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003 2. System Engineering2. System Engineering

• Action items from PDR and Delta PDR

• Requirements & specifications

– Requirements flow-down

– Requirements list showing key requirements

• Interface control

– List of all interfaces and status

– Major trades in support of interface finalization

– Documentation status, open issues/TBX’s and closure plans

• Technical budget allocation updates

– Technical budgets (mass, volume, power/thermal)

– Allocation flow down to subsystems

• Parts and materials

– Parts, material, and process list status

– Pending issues


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003PDR Action ItemsPDR Action Items

• 23 action items were assigned to Mechanical Systems at the January PDR

• All have been addressed, and submitted for closure

• Actions grouped into 5 classes

– Thermal Design: re-evaluate thermal interface requirements and re-design thermal system accordingly

– Structural Design: use positive shear restraint, when possible, at all key interfaces

– Fabrication and Integration: evaluate integration contingency and costs

– Environmental Testing: amplify test plans

– Risk: mitigate and manage development and fabrication risks


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003PDR Action Items (cont 1)PDR Action Items (cont 1)

• Thermal Design: Re-evaluate thermal interface requirements and re-design thermal system accordingly

– System-level trades have been accomplished with GLAST Mission input

– External interface definition has been improved: LAT IRD updated with significant additions. Optical properties of viewable SC surfaces have been bounded.

– Switched radiator coating to 0.25 mm FOSR, with emissivity = 0.85 (6% improvement)

– Sensitivity studies of key LAT internal interfaces has been completed and interface designs modified as needed (TKR/Grid, E-Box/X-LAT are two examples)

– Re-packaging of Radiators has been completed for Delta PDR and updated with Spectrum involvement

– Responsibilities clarified: LAT is now responsible for survival heater control. All survival heater control is passive, including anti-freeze heaters on the VCHP’s.

– Added anti-freeze heaters to VCHP’s (power included in survival budget

– LAT attitude has been double-checked: for 0 < beta < 52 degrees, beta = 0 is the LAT hot-case orientation


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003PDR Action Items (cont 2)PDR Action Items (cont 2)

• Structural Design: use positive shear restrain, when possible, at all key interfaces

– Positive shear restraint in the form of pins, shoulder bolts, and lap joints are being used at all critical interfaces in the LAT except the CAL-Grid interface, where additional shear restraint is needed. At this location bolt pre-load and friction are being used.

• Fabrication and Integration: evaluate integration contingency and costs

– An impact assessment has been made of replacing a TKR module.

• Environmental Testing: Amplify test plans

– LAT Verification Plan has been greatly amplified and released• Strength qualification plans included• Sine test philosophy is included

– Added Grid Box thermal-vacuum testing to the Mechanical Systems Test Plan and matrix

– Preliminary analysis of cool-down times for thermal-vacuum cycling have been completed.

– Subsystem and LAT test temperature have been established, and are collected in LAT-SS-00778, “LAT Environmental Specification.”

• Risk: Mitigate and manage development and fabrication risks

– The LM heat pipe facility has been returned to the Sunnyvale plant and was certified in December 2003.

– Six-month schedule extension has reduced schedule risk associated with cost-driven late fabrication of Radiators

– A Delta-PDR for Mechanical Systems was successfully held in July, 2002.

– LAT program risk management has been fully re-vamped, and all Mechanical Systems risks are continuously updated and action plans evaluated.


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Delta PDR Action ItemsDelta PDR Action Items

• 19 action items were assigned to Mechanical Systems at the July Delta-PDR

• All have been addressed and submitted for closure

• Actions are grouped into 5 classes

– Thermal Design: Investigate off-design thermal cases and impact of trades on parallel heat transfer paths within the LAT

– Structural Design: Evaluate stress concentrations within, and venting of Radiators

– Fabrication and Integration: assess inspection and contamination issues as they may affect LAT

– Environmental Test: finalize thermal test levels and cycles

– Risk: Implement a continuous risk management systems for Mechanical Systems


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Delta PDR Action Items (cont 1)Delta PDR Action Items (cont 1)

• Thermal Design: Investigate off-design thermal cases and impact of trades on parallel heat transfer paths within the LAT

– Analysis of the impact of heat pipe failures have been completed. The designs are fully redundant, being able to accommodate the loss of any heat pipe

– Shimmed and bolted interface conductances and radiative couplings have been updated to reflect the final CDR designs

– Transfer orbit thermal analysis has been started, using the draft timeline from Spectrum

• Structural Design: Evaluate stress concentrations within, and venting of Radiators

– Complete stress analysis of the Radiator VCHP’s has been completed, and will be shown at CDR

– Venting of Radiator panels has been addressed with vented honeycomb and close-outs.


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Delta PDR Action Items (cont 2)Delta PDR Action Items (cont 2)

• Fabrication and Integration: assess inspection and contamination issues as they may affect LAT.

– IR camera inspection of the Radiators has been budgeted.

– Ground cooling requirements during LAT integration have been defined (LAT-TD-00997)

– LAT CCP has been released, and all subsystems are working to it. A LAT low-temperature bake-out is part of that.

• Environmental Test: finalize thermal test levels and cycles.

– Test temperatures for all subsystems and the LAT have been finalized (LAT-SS-00778), and include a minimum AT margin of 5 C and QT margin of 10 C over operating

– LAT Verification Plan has baselined 8 thermal cycles of the VCHP joints.

– LAT thermal test program staffed adequately

• Risk: implement a continuous risk management systems for Mechanical Systems

– The LAT has completely updated its CRM system, using the GLAST program system at NAS/GSFC. This is managed by the LAT System Engineer, and includes risks and mitigation plans for all subsystems, including Mechanical Systems.


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Requirements Flow-DownLAT Requirements Flow-Down

Mission SystemSpecification

433-SPEC-0001

ScienceRequirements

Document433-SRD-0001

LAT-SC InterfaceRequirements

Document433-IRD-0001

LAT PerformanceSpecification

LAT-SS-00010

ACD SubsystemSpecification

LAT-SS-00016

TKR SubsystemSpecification

LAT-SS-00017

CAL SubsystemSpecification

LAT-SS-00018

Trigger & DataflowSubsystem

SpecificationLAT-SS-00019

SASSubsystem


LOFSubsystem


PowerSubsystem


MechanicalSubsystem


Mis

sio

nL

AT

Su

bs

ys

tem

ScienceRqmts

MissionRqmts

Ground System Rqmts

InterfaceRqmts

Interface Rqmts

TCS PerformanceSpecification

LAT-SS-00715

SAS DesignSpecification

LAT-SS-00505

CAL DesignSpecification

LAT-SS-00210

LAT TriggerSpecification

LAT-SS-00284

LAT TKR DesignSpecification

LAT-SS-00134

LAT OperationsFacility


Tower PowerSupplies


ACD DesignSpecification

LAT-SS-00352

De

sig

n S

pe

cif

ica

tio

n LAT DataflowSpecification

LAT-SS-00285

LAT Flight SWSpecification

LAT-SS-00399

LAT ReadoutElectronic


LAT IOC/MOC/SSC Interface

ControlDocuments

Radiator DesignSpecification

LAT-SS-00394

X-LAT PlateDesign


Grid Box DesignSpecification

LAT-SS-00775

LAT-SC InterfaceControl Document

LATEnvironmentalSpecification

LAT-SS-00778

LAT IOCPerformanceSpecification

LAT-SS-00015

Legend GLAST Mission Spec’s LAT Spec’s Subsystem Spec’s


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Key LAT Structural and Thermal RequirementsKey LAT Structural and Thermal Requirements

Parameter Requirement Design Margin ComplyVer.

MethodLAT Configuration

LAT mass allocation < 3000 kg 2679.4 kg 320.6 kg Y MMax Radiator area (#) < 5.88 m2 5.57 m2 0.31 m2 Y IConfigured as 2 separate Radiators OK Y IRadiator max width (#) < 1.903 m 1.896 m 7 mm Y IPositioned according to IRD App. A (#) > 1.84 m sep 1.863 m 22.6 mm Y IMount point for SC support as shown in IRD Appendix A (#)

1.177 m below LIP

OK Y I

Structural, LoadsFixed-base first-mode > 50 Hz 11% Y T

TKR alignment during normal LAT operation< 7arc-sec 1s

radial4.1 arc-sec peak-

to-peak2.9 arc-sec + 5s Y T, A

Capable of exposure to static-equivalent launch loads

OK Y T, A

Capable of exposure to sinusoidal vibration launch loads

OK Y T

Capable of exposure to acoustic launch loads OK P T


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Key LAT Structural and Thermal RequirementsKey LAT Structural and Thermal Requirements

Parameter Requirement Design Margin ComplyVer.

MethodThermal

Capable of normal operation when loaded by 75 W/Rad of heat from SC solar arrays

75 W/Rad 73.4 W/Rad OK Y T, A

Capable of normal operation with Rad-Solar Array view factor = 0.1

OK Y A

Orbit range of 450 km min to 575 km max 450 - 575 km 450 km OK Y AProvide thermal control with LAT pointed 2pi/24/7/365 during any normal LAT mode

OK Y T, A

Capable of maintaining thermal control during exposure to IR, Albedo, Solar fluxes

OK Y T, A

Capable of maintaining thermal control when exposed to solar flux from SC re-points

OK Y T, A

Power

Max process power indefinite dissipation 650 W @

T(max)612 W LAT + 38 W

Rad @ 24 C1 C operating +

5 C calcY T, A

Peak process power dissipated for 10 min720 W for 10 min @ T(max)

720 W for 20 min @ <T(max)

10 min, 7 C Y T, A

VCHP heater power when LAT is on (at Vmin) < 38 W 13 W @ 27 V 25 W Y DVCHP heater power when LAT is off (at Vmin) < 50 W 42 W @ 27 V 8 W Y DOrbit-average survival heater power at min voltage (not incl control authority)

< 220 W 142 W 55% (78 W) Y D

Peak survival heater power < 560 W362 W (incl 30%

control auth)55% (198 W) Y D

During Obs t-vac, TCS capable of full functionality "lying on its side"

OK Y T, A


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Block DiagramLAT Block Diagram

TKR ModuleCFC tray, side walls

Gridmonolithic alum structure

CAL Modulesalum bottom plate

Elec. Boxesalum electronics box

MLI InsulationMLI surrounding underside of LAT

ACDBase Elec Ass’y alum frame

LAT Radiatorson +/- Y sides of LAT Grid

SpacecraftLAT mounting structure

SpacecraftSC bus structure

Solar ArraysS.A. mount

MLISurrounding ACD

LAT Block DiagramLAT Block Diagram

X-LAT Platemonolithic alum structure

Radiator Mnt BktSupport Radiators at corners of Grid

EMI SkirtShields E-Boxes, supports X-LAT Pl

Htr Switch BoxesOperate Radiator heaters


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT System Schematic DiagramLAT System Schematic Diagram

Rad

iato

rRad

iato

r

Grid Base Ass’y

CAL

TKR

ACD

X-LAT Plate

EM

I S

kir

tRadMntBkt

Electronics

Htr SwBox

Spacecraft

LV Payload Attach Fitting

EM

I Skirt

RadMntBkt

Htr SwBox

SolarArray

SolarArray

Thermal

Structural

EMI/Grounding

Accommodation

Direction of arrow signifiesdirection of reliance, structuralsupport or heat flow

LAT Schematic DiagramLAT Schematic Diagram


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Internal InterfacesLAT Internal InterfacesInterface Structural Thermal Grounding/Shielding Accommodation

TKR Grid8 Ti flexures/bay, bolted and pinned to Grid

Cu thermal straps from TKR sidewalls dry-bolted to Grid

Slots in Grid provide race ways for TKR flex cables

CAL GridBolted tabs in CAL back plate develop shear at joint

Tab dry-joint under high bolt pre-load transfers CAL heat to Grid

Mating alum surfaces are alodined for AC/DC grounding

E-Boxes CAL4 Ti stand-offs/bay support E-Box stack off CAL module

Low-conductivity stand-offs and surface finishes minimize heat transfer

E-Box and CAL alum surfaces alodined for AC/DC grounding

E-Boxes X-LATE-Boxes support X-LAT Plate against out-of-plane deflection

Thermal straps transfer E-Box heat to X-LAT Plate

ACD GridCorner bolts and mid-side bolts/pins

Bolted dry joint and radiative coupling transfers ACD heat to Grid


TKR ACDTKR black-painted sidewalls view ACD inner CFC honeycomb facesheet

RadiatorRad Mnt

BktBolted/pinned joints carry all Radiator loads

Isolating gasket minimizes survival heat-leak from Grid

Rad Mnt Bkt

GridBolted/pinned joints carry Radiator and Switch Box loads


Grid RadiatorVCHP's mount to HP patch plate hanging from Grid

VCHP-DSHP silicone wet joint is primary heat path for Grid heat

Switch Box

Rad Mnt Bkt

Switch box bolted to Rad Mnt Bkt

Silicone wet joint removes small heat load to Rad Mnt Bkt

Shielded cables carry ground

E-Boxes EMI Skirt Skirt shields internal E-Boxes Connectors mount to Skirt EMI Skirt Grid Bolted joint Taped for EMI shielding

X-LAT EMI Skirt Bolted, pinned joint Taped for EMI shielding

X-LAT RadiatorVCHP-XLHP silicone wet joint is heat path for Elec heat off X-LAT

Interface is low risk and is f inalized

Interface design not yet f inalized or tested

Interface design is incomplete


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Trades Associated With Internal Interface FinalizationTrades Associated With Internal Interface Finalization

Trade Topic Status Study ConclusionACD and TKR survival temperatures and impact of black paint on TKR sidewalls

Complete Evaluate impact of using high-emissivity black paint on TKR and ACD survival temps

Black paint raises ACD survival temps, which increases margins at QT, while having little impact on TKR survival temps. Also adds redundant thermal path for TKR

Radiator panel cut-outs and top profile

Complete Find balance between maximizig radiating surface area, structural stiffness of panel top, and integration access to VCHP joints

Stepped profile was baselined. Area is maximized, while providing good access volume under the ACD. Panel stiffness is not significantly affected.

Electronic box mounting Complete Investigate hard-mounting the E-Boxes to the CAL plate, and making compliant thermal joints to the X-LAT Plate

Changed baseline to hard-mount to CLA, to simplify structural and I&T plans. Incorporated thermal straps into the X-LAT Plate for heat removal

CAL bolted joint to the Grid Working Investigate alternate design implementations for the bolted joint, and the impact of new grounding requirements

Test results of friction testing have been used to finalize the design. Alodine surface treatment baselined, but electrical testing has not been complete. Shear allowables and margins still being worked

TKR to Grid thermal joint Complete Develop new thermal interface in response to changes in the TKR bottom tray design changes

Cu thermal strap baselined. This improves thermal joint reliability. Changes to Grid interface decreases integration risk, at cost of increased time to bolt on straps


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Internal Interface TBX’s and Open IssuesInternal Interface TBX’s and Open Issues

• Tracker-LAT interface

– 0 TBX’s in ICD

– Interface drawing in draft: working on final tolerancing

– Open issue: TKR-Grid copper thermal straps• Being worked by TKR group• Detailed design is complete and in the interface drawing and testing is underway• Closure plan

– TKR to complete thermal testing as part of EM test plan closure

• Calorimeter-LAT interface

– 0 TBX’s in ICD

– Interface drawing in final draft

– Open issue: CAL-Grid bolted friction joint• Being worked by Mechanical Systems• Friction testing is complete and preliminary joint allowables established• EM testing of joint and 1 x 4 Grid will complete qualification process• Friction joint design has been questioned by GSFC• Currently under discussion with GSFC mechanical branch

• ACD-LAT ICD interface

– 4 TBX’s in ICD: all have been resolved and will be included in the next revision (in release cycle)

– Interface drawing in final draft: finalize fit of mating pieces

– Open issues: none


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Internal Interface TBX’s and Open Issues (cont)Internal Interface TBX’s and Open Issues (cont)

• Electronics-LAT interface

– # TBX’s

– Interface drawing in second draft: awaits X-LAT interface resolution

– Open issue: X-LAT Plate to Electronics box thermal joint• Baseline thermal strap design identified to not meet thermal or structural requirements• LAT tiger team convened to resolve interface issues—preliminary thermal design developed,

using vel-therm and parallel thermal paths• Closure plan

– Incorporate preliminary thermal design into LAT system model to confirm design meets interface temperature requirements (underway)

– Finalize X-LAT and E-box structural interface to work around thermal design

– Open issue: Heater Switch Box mounting• Switch box design has been finalized, but interface to Radiator Mount Bracket is TBD• Closure plan

– Establish interface req’s: loads, heat transfer– Finalize mounting design: bolt sizing, thermal and electrical interface

– Open issue: Finalize TCS interface requirements• Details of interface and functionality requirements have not been finalized• Closure plan

– Finalize TCS Performance Specification– Use this to spec interface and functionality requirements for Elec-LAT ICD


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Interface Requirements Documentation StatusInterface Requirements Documentation Status

LAT Internal Interface Control SpecificationsLAT Internal Interface Control Specifications

Document StatusLAT Instrument

LAT-DS-00040-5: LAT Instrument Layout Released 6 May 02. Revision in progressLAT-DS-00038-3: LAT Instrument Layout Rev 3 complete; out for review

CalorimeterLAT-DS-00233-3: CAL-LAT Interface Definition Drawing Final draft out for subsystem reviewLAT-SS-00238-4: CAL-LAT Mech, Therm, Elec Interface Control Document Released 13 Mar 03

ACDLAT-DS-00309-1: ACD-LAT Interface Definition Drawing Final draft out for subsystem reviewLAT-SS-00363-4: ACD-LAT Mech, Therm, Elec Interface Control Document Released 17 Dec 02

TrackerLAT-DS-00851-1: TKR-LAT Interface Definition Drawing First draft in-progressLAT-SS-00138-5: TKR-LAT Mech, Therm Interface Control Document In Signature CycleLAT-SS-00176-2: TKR-LAT Elec Interface Control Document Released 27 Jan 03

ElectronicsLAT-DS-01630-1: Electronics-LAT Interface Definition Drawing First draft in-progressLAT-SS-01794-1: Elec-LAT Mech, Therm Interface Control Document First draft in-progress


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT External InterfacesLAT External Interfaces

Interface Structural Thermal Grounding/Shielding Accommodation

Radiator SC BusSC struts restrain Radiator against out-of-plane loads

MLI on both surfaces to minimize radiative coupling

Radiator size/position fit around SC, flexures

Solar Arrays

RadiatorCold-/hot-case SA backloading affect peak LAT temp's, survival heater needs

Cut-out in Radiator allows SA boom to pass through

GridSC

FlexuresBracket below Grid accepts bolts, pins from Flexure

Grid Bracket allows for SC attach

EMI SkirtSC

FlexuresSkirt is recessed for clearance to flexure

X-LAT SC BusMLI on both surfaces to minimize radiative coupling

Cable tie-downs to support SC cables

Interface is low risk and is f inalized

Interface design not yet f inalized or tested

Interface design is incomplete


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Trades Associated With External Interface FinalizationTrades Associated With External Interface Finalization

Trade Topic Status Study ConclusionEffect of solar array properties and view factor on LAT cold-/survival-cases

Complete Evaluate definition of cold-case SA that is suitably conservative for Spectrum, without driving LAT to higher survival heater power needs

Agreed-to SA parameters delineated in LAT-TD-00224. Heater power allocations finalized in LAT IRD

Radiator panel size and location

Complete Finalize Radiator size to work with Spectrum solar arrays

Stay-clear dimensions and placement finalized, along with cut-outs for solar array accommodation

LAT-SC flexure mounting feature

Working Develop a balanced interface design to attenuate loads into the Grid and make the joint more accessible during Observatory integration

Wing bracket base lined to reduce stress concentrations in the Grid, whil providing a bolted joint with better access from the sides. This cleans up the SC flexure design. Impact of pin envelope requirements on EMI Skirt stayclear is still in work


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003External Interface TBX’s and Open IssuesExternal Interface TBX’s and Open Issues

• Interface requirements documents

– Interface design maturation has superseded much of requirements documents

– Closure plan• Work with GLAST project to update IRD, MSS to be bring them up to date with latest agreements

• SC Flexure to LAT mounting design is not finalized

– Actively working design concepts with Spectrum

– Hanging Wing bracket design concept is baselined

– Working SC shear pin envelope with respect to EMI Skirt stay-clear

– Impact on LAT design is well-understood

– Closure plan• Work to final concept by mid-April• Incorporate into LAT-DS-00040 drawing and Spectrum ICD by LAT CDR

• Lateral center-of-mass requirement flow-down to LAT

– LAT center of mass requirement is being developed by Spectrum as part of ACS maturation, in conjunction with LAT input

– LAT has evaluated expected worst-case center-of-mass offsets

– Closure plan• Spectrum: evaluate impact of this on ACS/de-orbit and propose compromise


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Metrics: MassLAT Metrics: Mass

• UPDATE. SHOW ALLOCATION FLOW-DOWN TO SUBSYSTEMS AND CHANGES SINCE dPDR

Source: LAT-TD-00564-06 “LAT Mass Status Report, Mass Estimates for March 2003,” 7 March 2003

Parameter Requirement Design Margin ComplyLAT Mass < 3000 kg 2679.4 kg 320.6 kg YLAT center of mass above L.I.P. < 185 mm 149.3 35.7 mm Y

LAT Mass StatusLAT Mass Status

2400

2500

2600

2700

2800

2900

3000

Oct

-99

Jan-

00A

pr-0

0Ju

l-00

Oct

-00

Jan-

01A

pr-0

1Ju

l-01

Oct

-01

Jan-

02A

pr-0

2Ju

l-02

Oct

-02

Jan-

03A

pr-0

3Ju

l-03

Oct

-03

Jan-

04A

pr-0

4Ju

l-04

Oct

-04

Jan-

05A

pr-0

5

Date

Mas

s (k

g)

Mass Budget

Review Threshold

Total Allocated to S.S.

LAT Mass Estimate

I-PDR

I-CDR

I-SRR

10.9%

I-PSR

LAT Reserve

LAT Margin5.4%

Prop

dPDR

Subsystem Allocation

March 2003Mass (kg) Estimate Alloc.

TKR 504.9 510.0CAL 1375.8 1440.0ACD 270.1 280.0Mech 329.3 345.0Elec 199.3 220.0

LAT Total 2679.4 2795.0Rsrv/Margin 320.6Rsrv/Margin* 12.0%Allocation 3000.0* AIAA G-020 recommended min reserve = 7.2%

Center of Mass (mm)CMx 1.26 -20 < CMx < 20CMy -0.54 -20 < CMy < 20CMz -86.89 CMz < -51.2Ht off LIP 149.31 Ht < 185

Second Moment of Inertia (kg-m2)Ixx 1057.7 1500.0Iyy 1014.9 1500.0Izz 1339.5 2000.0


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Metrics: Mass (cont)LAT Metrics: Mass (cont)

Subsystem Mass Estimates (kg) AIAA Center of Mass Location

SubsystemCurrent Alloc.

PARA CALC MEAS TotalReserve

Estimate (*)CMx (mm)

CMy (mm)

CMz (mm)

TKR 510.0 0.0 504.9 0.0 504.9 2.0% 0.00 0.00 229.95CAL 1440.0 53.0 26.5 1296.3 1375.8 3.0% 0.00 0.00 -148.75ACD 280.0 35.5 209.6 25.1 270.1 12.4% 0.00 0.00 318.19Mech (+) 345.0 143.2 186.0 0.0 329.3 21.0% 0.00 0.00 -485.61DAQ Elec (#) 220.0 150.6 48.7 0.0 199.3 20.0% 16.90 -7.20 -352.88LAT Total 2795.0 382.3 975.8 1321.3 2679.4 7.2% 1.26 -0.54 -86.89% of Total 14.3% 36.4% 49.3% 100.0% Grid height 236.20"Current" A llocations per CCB action on 7 Mar 03 Ht above LAT Interface Plane 149.31

(*) Recommended reserves estimated using guidelines given in ANSI/AIAA G-020-1992 "Estimating and Budgeting Weight and Power Contingencies for Space Craft Systems“

(+) “Mech” includes the Grid, X-LAT Plates, Radiators, and EMI Shield pieces

(#) “DAQ Elec” includes all power, communications, and trigger and dataflow systems (PDU, SIU, TEM/TPS/GASU respectively)

Source: LAT-TD-00564-06 “LAT Mass Status Report, Mass Estimates for March 2003,” 7 March 2003

LAT Subsystem Mass StatusLAT Subsystem Mass Status


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Metrics: DimensionsLAT Metrics: Dimensions

• LAT instrument and subsystem stay-clears are governed by Interface Definition Drawings

– LAT-SC stay-clears delineated in LAT-DS-00040-8 (reproduced in 433-IRD-0001)

– Subsystem stay-clears, interface features, datums, and tolerances established by the IDD’s with each subsystem

Delta PDR Dimensions CDR Dimensions (#)Parameter Req Design Req Design Margin Comply

LAT width at ACD < 1800 1796 < 1800 1796 SC 4 YLAT width at Grid < 1800 1796 < 1820 1806 SC 14 YInstrument height above LIP < 1100 1047 < 1100 1081.5 SC 18.5 YHeight below LIP < 300 258.25 < 300 258.25 41.75 YRadiator inside spacing > 1890 1895.5 >1840 1843 SC 3 YRadiator width < 1851 1850 < 1903 1900 SC 3 YLAT circle diameter inside fairing < 2743 2718 < 2743 2718 25 Y(#) Requirements per agreement among LAT, GLAST, Spectrum Astro. IRD requirements not yet updated by GLAST

Source: LAT-DS-00040-08 “LAT Instrument Stay Clear,” 12 Feb 2003 Draft LAT-DS-01221-01, “Radiator-LAT Interface Definition Drawing,” 26 Feb 2003 Draft LAT-DS-00309-03, “ACD-LAT Interface Definition Drawing,” 20 Feb 2003 Draft

Key LAT Stay-Clear DimensionsKey LAT Stay-Clear Dimensions


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Metrics: Dimensions (cont)LAT Metrics: Dimensions (cont)

LAT Stay-Clear AssemblyLAT Stay-Clear Assembly


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Metrics: PowerLAT Metrics: Power

Parameter Requirement Design Margin ComplyLAT orbit-average power < 650 W 590 W 60 W YPeak power < 750 W 720 W 30 W Y

Special Status Normal Operations Quantity

Surv.Tran-sition

Cold Case

Alloc.Hot

Case10 Min Peak

Unit Hot Cold Comments

Total 50.0 95.3 534.8 590.0 650.0 719.8 WTotal on Grid 0.0 0.0 210.6 234.0 252.1 291.2 W

TKR 139.5 155.0 162.8 192.9 W 16 Evenly distributed up 4 sides of TKR moduleCAL 60.3 67.0 75.8 83.4 W 16 Evenly distributed up 4 sides of CALACD 10.8 12.0 13.6 14.9 W 1 Evenly distributed around 4 sides of BEA

Total on X-LAT 0.0 45.3 286.2 318.0 359.9 390.5 WTEM 43.2 48.0 54.3 58.1 W 16 1 board/bayTPS 148.5 165.0 186.7 203.2 W 16 1 P.S. board/bay for TEMGASU 19.8 22.0 24.9 27.8 W 1 1 1 lg board spanning 4 center baysSIU 27.2 21.6 24.0 27.2 29.7 W 1 1 2 bds in 2 bays (1 hot, 1 cold)EPU 38.7 43.0 48.7 53.0 W 2 1 2 bds in 2 bays, both hot (+ 1 cold spare)PDU 18.1 14.4 16.0 18.1 18.6 W 1 1 2 bds in 2 bays (1 hot, 1 cold)

Radiators 50.0 50.0 38.0 38.0 38.0 38.0 W 16 16 Bottom of Radiator panels at VCHP's

LAT Dissipated Power ValuesLAT Dissipated Power Values

Source: LAT-TD-00225-04 “A Summary of LAT Dissipated Power for Use in Thermal Design”, 13 Mar 2003


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Metrics: Power (cont 1)LAT Metrics: Power (cont 1)

Source: LAT-TD-00225-04 “A Summary of LAT Dissipated Power for Use in Thermal Design”, 13 Mar 2003

Cold Case Power Dissipation Hot Case Power Dissipation

Bay 12EPU-B

Bay 13Empty

Bay 14Empty

Bay 15Empty

Bay 12EPU-B

Bay 13Empty

Bay 14Empty

Bay 15Empty

0 0 0 0 0 0 0 0

Bay 8PDU-B

Bay 9GASU

Bay 10GASU

Bay 11SIU-B

Bay 8PDU-B

Bay 9GASU

Bay 10GASU

Bay 11SIU-B

0 9.9 0 0 0 12.4 0-X Side

Bay 4PDU-A

Bay 5GASU

Bay 6GASU

Bay 7SIU-A

+X SideSun Side

-X SideBay 4PDU-A

Bay 5GASU

Bay 6GASU

Bay 7SIU-A

+X SideSun Side

14.4 9.9 21.6 18.11 0 12.4 27.2

Bay 0EPU-A

Bay 1Empty

Bay 2Empty

Bay 3EPU-A

Bay 0EPU-A

Bay 1Empty

Bay 2Empty

Bay 3EPU-A

19.4 0 0 19.4 24.3 0 0 24.3

Boxes 94.5 Boxes 118.8TEM/TPS: 191.7 TEM/TPS: 241.0X-LAT Tot 286.2 X-LAT Tot 359.9

Legend: Notes:GASU Global trigger, ACD, and Switching Unit 1. All power is in wattsSIU Spacecraft Interface UnitPDU Power Distribution BoxEPU LAT Event Processor-A A-side, powered box-B B-side, unpowered cold spare

LAT Top View

-Y SideLAT Radiator

+Y SideLAT Radiator

+Y SideLAT Radiator

-Y SideLAT Radiator

LAT Top View

LAT +X

LAT +Y

LAT +X

LAT +Y

LAT Dissipated Power DistributionLAT Dissipated Power Distribution


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT Materials and PartsLAT Materials and Parts

• Material requirements

– Source: 433-MAR-0001, “Mission Assurance Requirements”

– LAT: LAT-SS-00107-01, “Mechanical Parts Plan”

• Material Usage Agreement (MUA) needed for non-compliant materials

– All materials have been assessed by GSFC materials branch to be compliant to standards and used in conventional methods

– Currently the project requires no MUA’s

• Relevant procedures and guidelines for material selection

– Metallic Materials for Stress Corrosion Cracking Resistance in Sodium Chloride Environment (MSFC-STD-3029)

– Fastener Integrity Requirements (541-PG-8072.1.2)

– Standard Test Method for Total Mass Loss and Collected Volatile Condensable Materials for Outgassing (ASTM-E-595)

Total Materials

SubmittedSLAC IPO Accepted

GSFC Approved

Pending

ACD 97 97 97 0CAL 45 41 41 4Elec 24 21 21 3I & T 0 0 0 TBDMech 117 104 104 13TKR 51 41 41 10Total 334 304 304 30

Source: LAT-DS-00405, “LAT Mechanical Materials and Parts List,” March 2003

Total Materials Count on LAT M&P ListTotal Materials Count on LAT M&P List


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT M&P List: Inorganic, Polymer and Composite MaterialsLAT M&P List: Inorganic, Polymer and Composite Materials

• Inorganic materials

– Inorganic materials submitted to LAT IPO as of 19 March 2003

• Polymers and Composites

– Polymer and composite materials submitted to LAT IPO as of 19 March 2003

Inorganic Materials


GSFC Approved

Pending



Inorganic Materials Count on LAT M&P ListInorganic Materials Count on LAT M&P List

Polymer and Composite Materials


GSFC Approved

Pending


Polymer and Composite Materials Count on LAT M&P ListPolymer and Composite Materials Count on LAT M&P List


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003LAT M&P List: Lubricants and ProcessesLAT M&P List: Lubricants and Processes

• Lubricants

– Lubricants used only in static applications, largely for bolts

– No moving parts within the LAT

– Lubricants submitted to LAT IPO as of 19 March 2003

• Processes

– M & P list collects process information for all heat treating and surface treatment processes

– Processes submitted to LAT IPO as of 19 March 2003

Lubricants


GSFC Approved

Pending



Lubricant Count on LAT M&P ListLubricant Count on LAT M&P List

Processes


GSFC Approved

Pending


Processes on LAT M&P ListProcesses on LAT M&P List


GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Materials List Pending ItemsMaterials List Pending Items

• Pending items as of 19 March 2003

• Reasons for status

– Specific material not yet chosen

– Waiting for “TBD’s” to be filled in

– Outgassing testing in progress

• Mechanical Parts Review Board will evaluate materials once missing information is collected from test results or work with manufacturer

• Final step is to validate materials list

– Cross-check against drawing list

– Check for missing materials and processes

Materials Pending Approval

Material ID is TBD

Lacking Info for

Approval

Needs Qual

Testing

Change Material

Tested for Out-gassing

Total Pending

ACD 0 0 0 0 0 0CAL 0 0 0 0 4 4Elec 0 2 0 1 0 3I & T TBD TBD TBD TBD TBD TBDMech 12 1 0 0 0 13TKR 0 0 2 1 8 10Total 12 3 2 2 12 30

Materials Pending Materials Branch ApprovalMaterials Pending Materials Branch Approval



GLAST LAT Project

Mechanical Design Integration Peer Review, March 2003Summary and Further WorkSummary and Further Work

• Summary

– Internal and External interfaces have been clearly defined

– Remaining interface issues are identified and a closure plan is in progress

– Mass and Power allocations are understood and being tracked with subsytems

– M&P list is up-to-date with subsystems

• Further Work

– Complete interface documentation

– Complete interface closure plans to finalize interfaces

– Validate M&P list against subsystem drawing trees