GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Mechanical Design Integration Peer Review, March 2003
2. System Engineering
Martin Nordby
nordby@slac.stanford.edu
24 March 2003 rev 3
LAT-PR-01278 Section 2
2-1
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
2. 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
LAT-PR-01278 Section 2
2-2
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
PDR 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
LAT-PR-01278 Section 2
2-3
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
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 hotcase orientation
LAT-PR-01278 Section 2
2-4
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
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-SS00778, “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.
LAT-PR-01278 Section 2
2-5
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Delta 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
LAT-PR-01278 Section 2
2-6
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
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.
LAT-PR-01278 Section 2
2-7
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
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 lowtemperature 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.
LAT-PR-01278 Section 2
2-8
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT Requirements Flow-Down
Mission
Science
Requirements
Document
433-SRD-0001
Science
Rqmts
Mission System
Specification
433-SPEC-0001
LAT
Design Specification
Subsystem
LAT-SS-00010
Mechanical
Subsystem
Specification
LAT-SS-00115
TCS Performance
Specification
LAT-SS-00715
LAT
Environmental
Specification
LAT-SS-00778
Ground System Rqmts
Interface
Rqmts
LAT IOC
Performance
Specification
LAT-SS-00015
LAT-SC Interface
Control Document
Trigger & Dataflow
Subsystem
Specification
LAT-SS-00019
TKR Subsystem
Specification
ACD Subsystem
Specification
LAT-SS-00017
LAT-SS-00016
Radiator Design
Specification
LAT Dataflow
Specification
LAT TKR Design
Specification
LAT-SS-00394
LAT-SS-00285
LAT-SS-00134
X-LAT Plate
Design
Specification
LAT-SS-01240
LAT Trigger
Specification
LAT-SS-00284
LAT Readout
Electronic
Specification
LAT-SS-00152
Grid Box Design
Specification
LAT Flight SW
Specification
LAT-SS-00775
LAT-SS-00399
LAT-PR-01278 Section 2
Interface
Rqmts
Mission
Rqmts
LAT-SC Interface
Requirements
Document
433-IRD-0001
LAT Performance
Specification
LAT IOC/MOC/
SSC Interface
Control
Documents
Power
Subsystem
Specification
LAT-SS-00136
CAL Subsystem
Specification
Tower Power
Supplies
Specification
LAT-SS-01537
CAL Design
Specification
LAT-SS-00018
LAT-SS-00210
LOF
Subsystem
Specification
LAT-SS-00021
SAS
Subsystem
Specification
LAT-SS-00020
LAT Operations
Facility
Specification
LAT-SS-01783
SAS Design
Specification
LAT-SS-00505
ACD Design
Specification
LAT-SS-00352
Legend
GLAST Mission Spec’s
LAT Spec’s
Subsystem Spec’s
2-9
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Key LAT Structural and Thermal Requirements
Parameter
LAT Configuration
LAT mass allocation
Max Radiator area (#)
Configured as 2 separate Radiators
Radiator max width (#)
Positioned according to IRD App. A (#)
Mount point for SC support as shown in IRD
Appendix A (#)
Structural, Loads
Fixed-base first-mode
TKR alignment during normal LAT operation
Capable of exposure to static-equivalent launch
loads
Capable of exposure to sinusoidal vibration
launch loads
Capable of exposure to acoustic launch loads
LAT-PR-01278 Section 2
Requirement
Design
Margin
Comply
Ver.
Method
< 3000 kg
< 5.88 m2
2679.4 kg
5.57 m2
OK
1.896 m
1.863 m
320.6 kg
0.31 m2
Y
Y
Y
Y
Y
M
I
I
I
I
Y
I
Y
T
Y
T, A
OK
Y
T, A
OK
Y
T
OK
P
T
< 1.903 m
> 1.84 m sep
1.177 m below
LIP
7 mm
22.6 mm
OK
> 50 Hz
11%
< 7arc-sec 1s 4.1 arc-sec peak2.9 arc-sec + 5s
to-peak
radial
2-10
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Key LAT Structural and Thermal Requirements
Parameter
Thermal
Capable of normal operation when loaded by
75 W/Rad of heat from SC solar arrays
Capable of normal operation with Rad-Solar
Array view factor = 0.1
Orbit range of 450 km min to 575 km max
Provide thermal control with LAT pointed
2pi/24/7/365 during any normal LAT mode
Capable of maintaining thermal control during
exposure to IR, Albedo, Solar fluxes
Capable of maintaining thermal control when
exposed to solar flux from SC re-points
Power
Max process power indefinite dissipation
Peak process power dissipated for 10 min
VCHP heater power when LAT is on (at Vmin)
VCHP heater power when LAT is off (at Vmin)
Orbit-average survival heater power at min
voltage (not incl control authority)
Peak survival heater power
During Obs t-vac, TCS capable of full functionality
"lying on its side"
LAT-PR-01278 Section 2
Requirement
Design
Margin
Comply
Ver.
Method
75 W/Rad
73.4 W/Rad
OK
Y
T, A
Y
A
Y
A
OK
Y
T, A
OK
Y
T, A
OK
Y
T, A
Y
T, A
Y
T, A
Y
Y
D
D
OK
450 - 575 km
450 km
OK
650 W @
612 W LAT + 38 W 1 C operating +
T(max)
Rad @ 24 C
5 C calc
720 W for 10 720 W for 20 min @
10 min, 7 C
min @ T(max)
<T(max)
< 38 W
13 W @ 27 V
25 W
< 50 W
42 W @ 27 V
8W
< 220 W
142 W
55% (78 W)
Y
D
< 560 W
362 W (incl 30%
control auth)
55% (198 W)
Y
D
Y
T, A
OK
2-11
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT Block Diagram
MLI
Surrounding ACD
ACD
Base Elec Ass’y
alum frame
CAL Modules
alum bottom plate
TKR Module
CFC tray, side
walls
Grid
monolithic alum
structure
Spacecraft
LAT mounting
structure
Spacecraft
SC bus structure
Solar Arrays
S.A. mount
Elec. Boxes
alum electronics
box
EMI Skirt
Shields E-Boxes,
supports X-LAT Pl
X-LAT Plate
monolithic alum
structure
Radiator Mnt Bkt
Support Radiators
at corners of Grid
Htr Switch Boxes
Operate Radiator
heaters
LAT Radiators
on +/- Y sides of
LAT Grid
MLI Insulation
MLI surrounding
underside of LAT
LAT Block Diagram
LAT-PR-01278 Section 2
2-12
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT System Schematic Diagram
ACD
Thermal
Structural
EMI/Grounding
Accommodation
Direction of arrow signifies
direction of reliance, structural
support or heat flow
TKR
Grid Base Ass’y
Rad
Mnt
Bkt
Radiator
EMI Skirt
Electronics
X-LAT Plate
Spacecraft
Htr Sw
Box
Radiator
Solar
Array
CAL
EMI Skirt
Htr Sw
Box
Rad
Mnt
Bkt
Solar
Array
LV Payload Attach Fitting
LAT Schematic Diagram
LAT-PR-01278 Section 2
2-13
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT Internal Interfaces
Interface
TKR
Grid
CAL
Grid
E-Boxes
CAL
E-Boxes
X-LAT
ACD
Grid
TKR
ACD
Structural
8 Ti flexures/bay, bolted and
pinned to Grid
Bolted tabs in CAL back plate
develop shear at joint
4 Ti stand-offs/bay support EBox stack off CAL module
E-Boxes support X-LAT Plate
against out-of-plane deflection
Corner bolts and mid-side
bolts/pins
Rad Mnt Bolted/pinned joints carry all
Radiator
Bkt
Radiator loads
Rad Mnt
Bolted/pinned joints carry
Grid
Bkt
Radiator and Switch Box loads
VCHP's mount to HP patch
Grid
Radiator
plate hanging from Grid
Switch
Rad Mnt Switch box bolted to Rad Mnt
Box
Bkt
Bkt
E-Boxes EMI Skirt
EMI Skirt
Grid
Bolted joint
X-LAT EMI Skirt Bolted, pinned joint
X-LAT
Radiator
LAT-PR-01278 Section 2
Thermal
Cu thermal straps from TKR sidewalls
dry-bolted to Grid
Tab dry-joint under high bolt pre-load
transfers CAL heat to Grid
Low-conductivity stand-offs and surface
finishes minimize heat transfer
Thermal straps transfer E-Box heat to XLAT Plate
Bolted dry joint and radiative coupling
transfers ACD heat to Grid
TKR black-painted sidewalls view ACD
inner CFC honeycomb facesheet
Isolating gasket minimizes survival heatleak from Grid
Grounding/Shielding
Accommodation
Slots in Grid provide race
ways for TKR flex cables
Mating alum surfaces are
alodined for AC/DC grounding
E-Box and CAL alum surfaces
alodined for AC/DC grounding
Mating alum surfaces are
alodined for AC/DC grounding
Interface is low risk
and is finalized
Interface design not
yet finalized or tested
Interface design is
incomplete
Mating alum surfaces are
alodined for AC/DC grounding
VCHP-DSHP silicone wet joint is
primary heat path for Grid heat
Silicone wet joint removes small heat
load to Rad Mnt Bkt
Shielded cables carry ground
Skirt shields internal E-Boxes
Taped for EMI shielding
Taped for EMI shielding
Connectors mount to Skirt
VCHP-XLHP silicone wet joint is heat
path for Elec heat off X-LAT
2-14
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Trades Associated With Internal Interface Finalization
Trade Topic
ACD and TKR survival
temperatures and impact of
black paint on TKR sidewalls
Radiator panel cut-outs and
top profile
Electronic box mounting
CAL bolted joint to the Grid
TKR to Grid thermal joint
LAT-PR-01278 Section 2
Status
Study
Conclusion
Complete Evaluate impact of using high-emissivity black paint Black paint raises ACD survival temps, which increases
on TKR and ACD survival temps
margins at QT, while having little impact on TKR survival
temps. Also adds redundant thermal path for TKR
Complete Find balance between maximizig radiating surface Stepped profile was baselined. Area is maximized, while
area, structural stiffness of panel top, and
providing good access volume under the ACD. Panel
integration access to VCHP joints
stiffness is not significantly affected.
Complete Investigate hard-mounting the E-Boxes to the CAL Changed baseline to hard-mount to CLA, to simplify
plate, and making compliant thermal joints to the X- structural and I&T plans. Incorporated thermal straps into
LAT Plate
the X-LAT Plate for heat removal
Working Investigate alternate design implementations for the Test results of friction testing have been used to finalize the
bolted joint, and the impact of new grounding
design. Alodine surface treatment baselined, but electrical
requirements
testing has not been complete. Shear allowables and
margins still being worked
Complete Develop new thermal interface in response to
Cu thermal strap baselined. This improves thermal joint
changes in the TKR bottom tray design changes
reliability. Changes to Grid interface decreases integration
risk, at cost of increased time to bolt on straps
2-15
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Internal 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
•
•
•
•
Calorimeter-LAT interface
– 0 TBX’s in ICD
– Interface drawing in final draft
– Open issue: CAL-Grid bolted friction joint
•
•
•
•
•
•
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
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
LAT-PR-01278 Section 2
2-16
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
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
•
•
•
–
Open issue: Heater Switch Box mounting
•
•
–
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
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
LAT-PR-01278 Section 2
2-17
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Interface Requirements Documentation Status
Document
LAT Instrument
LAT-DS-00040-5: LAT Instrument Layout
LAT-DS-00038-3: LAT Instrument Layout
Calorimeter
LAT-DS-00233-3: CAL-LAT Interface Definition Drawing
LAT-SS-00238-4: CAL-LAT Mech, Therm, Elec Interface Control Document
ACD
LAT-DS-00309-1: ACD-LAT Interface Definition Drawing
LAT-SS-00363-4: ACD-LAT Mech, Therm, Elec Interface Control Document
Tracker
LAT-DS-00851-1: TKR-LAT Interface Definition Drawing
LAT-SS-00138-5: TKR-LAT Mech, Therm Interface Control Document
LAT-SS-00176-2: TKR-LAT Elec Interface Control Document
Electronics
LAT-DS-01630-1: Electronics-LAT Interface Definition Drawing
LAT-SS-01794-1: Elec-LAT Mech, Therm Interface Control Document
Status
Released 6 May 02. Revision in progress
Rev 3 complete; out for review
Final draft out for subsystem review
Released 13 Mar 03
Final draft out for subsystem review
Released 17 Dec 02
First draft in-progress
In Signature Cycle
Released 27 Jan 03
First draft in-progress
First draft in-progress
LAT Internal Interface Control Specifications
LAT-PR-01278 Section 2
2-18
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT External Interfaces
Interface
Radiator
Solar
Arrays
Structural
SC struts restrain Radiator
SC Bus
against out-of-plane loads
Radiator
Thermal
MLI on both surfaces to minimize
radiative coupling
Cold-/hot-case SA backloading affect
peak LAT temp's, survival heater needs
SC
Bracket below Grid accepts
Flexures bolts, pins from Flexure
SC
EMI Skirt
Flexures
Grid
X-LAT
SC Bus
MLI on both surfaces to minimize
radiative coupling
Grounding/Shielding
Accommodation
Radiator size/position fit
around SC, flexures
Cut-out in Radiator allows
SA boom to pass through
Grid Bracket allows for SC
attach
Skirt is recessed for
clearance to flexure
Cable tie-downs to support
SC cables
Interface is low risk
and is finalized
Interface design not
yet finalized or tested
Interface design is
incomplete
LAT-PR-01278 Section 2
2-19
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Trades Associated With External Interface Finalization
Trade Topic
Status
Study
Effect of solar array properties Complete Evaluate definition of cold-case SA that is suitably
and view factor on LAT coldconservative for Spectrum, without driving LAT to
/survival-cases
higher survival heater power needs
Radiator panel size and
Complete Finalize Radiator size to work with Spectrum solar
location
arrays
LAT-SC flexure mounting
Working Develop a balanced interface design to attenuate
feature
loads into the Grid and make the joint more
accessible during Observatory integration
LAT-PR-01278 Section 2
Conclusion
Agreed-to SA parameters delineated in LAT-TD-00224.
Heater power allocations finalized in LAT IRD
Stay-clear dimensions and placement finalized, along with
cut-outs for solar array accommodation
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
2-20
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
External Interface TBX’s and Open Issues
•
Interface requirements documents
– Interface design maturation has superseded much of requirements documents
– Closure plan
•
•
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 with GLAST project to update IRD, MSS to be bring them up to date with latest agreements
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
LAT-PR-01278 Section 2
2-21
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT Metrics: Mass
Parameter
LAT Mass
LAT center of mass above L.I.P.
Estimate
504.9
1375.8
270.1
329.3
199.3
2679.4
320.6
12.0%
Alloc.
510.0
1440.0
280.0
345.0
220.0
2795.0
3000.0
* AIAA G-020 recommended min reserve = 7.2%
Center of Mass (mm)
CMx
1.26
CMy
-0.54
CMz
-86.89
Ht off LIP
149.31
3000
LAT Margin
5.4%
2900
I-PSR
dPDR
10.9%
I-CDR
LAT Reserve
2800
Mass (kg)
March 2003
Mass (kg)
TKR
CAL
ACD
Mech
Elec
LAT Total
Rsrv/Margin
Rsrv/Margin*
Allocation
Requirement Design Margin Comply
< 3000 kg 2679.4 kg 320.6 kg
Y
< 185 mm
149.3 35.7 mm
Y
I-PDR
Subsystem Allocation
2700
Prop
I-SRR
2600
-20 < CMx < 20
-20 < CMy < 20
CMz < -51.2
Ht < 185
Mass Budget
Review Threshold
2500
Total Allocated to S.S.
LAT Mass Estimate
Second Moment of Inertia (kg-m2)
Ixx
1057.7
1500.0
Iyy
1014.9
1500.0
Izz
1339.5
2000.0
Oc
t -9
9
Ja
n- 0
0
Ap
r- 0
0
Ju
l-0
0
Oc
t -0
0
Ja
n- 0
1
Ap
r- 0
1
Ju
l-0
1
Oc
t -0
1
Ja
n- 0
2
Ap
r- 0
2
Ju
l-0
2
Oc
t -0
2
Ja
n- 0
3
Ap
r- 0
3
Ju
l-0
3
Oc
t -0
3
Ja
n- 0
4
Ap
r- 0
4
Ju
l-0
4
Oc
t -0
4
Ja
n- 0
5
Ap
r- 0
5
2400
Date
LAT Mass Status
Source: LAT-TD-00564-06 “LAT Mass Status Report, Mass Estimates for March 2003,” 7 March 2003
LAT-PR-01278 Section 2
2-22
•
U
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT Metrics: Mass (cont)
Subsystem Mass Estimates (kg)
Subsystem
TKR
CAL
ACD
Mech (+)
DAQ Elec (#)
LAT Total
% of Total
Current
Alloc.
510.0
1440.0
280.0
345.0
220.0
2795.0
PARA
CALC
MEAS
Total
0.0
53.0
35.5
143.2
150.6
382.3
14.3%
504.9
26.5
209.6
186.0
48.7
975.8
36.4%
0.0
1296.3
25.1
0.0
0.0
1321.3
49.3%
504.9
1375.8
270.1
329.3
199.3
2679.4
100.0%
"Current" Allocations per CCB action on 7 Mar 03
AIAA
Reserve
Estimate (*)
2.0%
3.0%
12.4%
21.0%
20.0%
7.2%
Center of Mass Location
CMx
CMy
CMz
(mm)
(mm)
(mm)
0.00
0.00
229.95
0.00
0.00
-148.75
0.00
0.00
318.19
0.00
0.00
-485.61
16.90
-7.20
-352.88
1.26
-0.54
-86.89
Grid height 236.20
Ht above LAT Interface Plane 149.31
LAT Subsystem Mass Status
(*) 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-PR-01278 Section 2
2-23
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT 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
Parameter
Req
Design
LAT width at ACD
< 1800
1796
LAT width at Grid
< 1800
1796
Instrument height above LIP
< 1100
1047
Height below LIP
< 300
258.25
Radiator inside spacing
> 1890
1895.5
Radiator width
< 1851
1850
LAT circle diameter inside fairing
< 2743
2718
Req
< 1800
< 1820
< 1100
< 300
>1840
< 1903
< 2743
CDR Dimensions (#)
Design
Margin Comply
1796 SC
4
Y
1806 SC
14
Y
1081.5 SC
18.5
Y
258.25
41.75
Y
1843 SC
3
Y
1900 SC
3
Y
2718
25
Y
(#) Requirements per agreement among LAT, GLAST, Spectrum Astro. IRD requirements not yet updated by GLAST
Key LAT Stay-Clear Dimensions
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
LAT-PR-01278 Section 2
2-24
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT Metrics: Dimensions (cont)
LAT Stay-Clear Assembly
LAT-PR-01278 Section 2
2-25
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT Metrics: Power
Parameter
Requirement
LAT orbit-average power
< 650 W
Peak power
< 750 W
Design
590 W
720 W
Margin Comply
60 W
Y
30 W
Y
Special Status
Normal Operations
Quantity
Tran- Cold
Hot
10 Min
Surv.
Alloc.
Unit Hot Cold
sition Case
Case
Peak
Total
50.0
95.3
534.8
590.0
650.0
719.8 W
Total 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
CAL
60.3
67.0
75.8
83.4 W
16
ACD
10.8
12.0
13.6
14.9 W
1
Total on X-LAT
0.0
45.3
286.2
318.0
359.9
390.5 W
TEM
43.2
48.0
54.3
58.1 W
16
TPS
148.5
165.0
186.7
203.2 W
16
GASU
19.8
22.0
24.9
27.8 W
1
1
SIU
27.2
21.6
24.0
27.2
29.7 W
1
1
EPU
38.7
43.0
48.7
53.0 W
2
1
PDU
18.1
14.4
16.0
18.1
18.6 W
1
1
Radiators
50.0
50.0
38.0
38.0
38.0
38.0 W
16
16
Comments
Evenly distributed up 4 sides of TKR module
Evenly distributed up 4 sides of CAL
Evenly distributed around 4 sides of BEA
1 board/bay
1 P.S. board/bay for TEM
1 lg board spanning 4 center bays
2 bds in 2 bays (1 hot, 1 cold)
2 bds in 2 bays, both hot (+ 1 cold spare)
2 bds in 2 bays (1 hot, 1 cold)
Bottom of Radiator panels at VCHP's
LAT Dissipated Power Values
Source: LAT-TD-00225-04 “A Summary of LAT Dissipated Power for Use in Thermal Design”, 13 Mar 2003
LAT-PR-01278 Section 2
2-26
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT Metrics: Power (cont 1)
Cold Case Power Dissipation
Hot Case Power Dissipation
LAT +Y
LAT +Y
+Y Side
LAT Radiator
Bay 12
EPU-B
Bay 13
Empty
Bay 14
Empty
Bay 15
Empty
Bay 12
EPU-B
Bay 13
Empty
Bay 14
Empty
Bay 15
Empty
0
0
0
0
0
0
0
0
Bay 8
PDU-B
Bay 9
GASU
Bay 10
GASU
Bay 11
SIU-B
Bay 8
PDU-B
Bay 9
GASU
Bay 10
GASU
Bay 11
SIU-B
9.9
0
0
0
12.4
0
Bay 6
GASU
Bay 7
SIU-A
Bay 4
PDU-A
Bay 5
GASU
Bay 6
GASU
Bay 7
SIU-A
9.9
21.6
18.11
0
12.4
27.2
0
-X Side
Bay 4
PDU-A
Bay 5
GASU
14.4
Boxes
TEM/TPS:
X-LAT Tot
Legend:
GASU
SIU
PDU
EPU
-A
-B
+Y Side
LAT Radiator
LAT +X
+X Side
Sun Side
-X Side
Bay 0
EPU-A
Bay 1
Empty
Bay 2
Empty
Bay 3
EPU-A
Bay 0
EPU-A
Bay 1
Empty
Bay 2
Empty
Bay 3
EPU-A
19.4
0
0
19.4
24.3
0
0
24.3
94.5
191.7
286.2
-Y Side
LAT Radiator
LAT Top View
Global trigger, ACD, and Switching Unit
Spacecraft Interface Unit
Power Distribution Box
LAT Event Processor
A-side, powered box
B-side, unpowered cold spare
Boxes
TEM/TPS:
X-LAT Tot
118.8
241.0
359.9
LAT +X
+X Side
Sun Side
-Y Side
LAT Radiator
LAT Top View
Notes:
1. All power is in watts
LAT Dissipated Power Distribution
Source: LAT-TD-00225-04 “A Summary of LAT Dissipated Power for Use in Thermal Design”, 13 Mar 2003
LAT-PR-01278 Section 2
2-27
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT 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)
ACD
CAL
Elec
I&T
Mech
TKR
Total
Total Materials
SLAC IPO GSFC
Submitted
Pending
Accepted Approved
97
97
97
0
45
41
41
4
24
21
21
3
0
0
0
TBD
117
104
104
13
51
41
41
10
334
304
304
30
Total Materials Count on LAT M&P List
Source: LAT-DS-00405, “LAT Mechanical Materials and Parts List,” March 2003
LAT-PR-01278 Section 2
2-28
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT 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
ACD
CAL
Elec
I&T
Mech
TKR
Total
Inorganic Materials
SLAC IPO GSFC
Submitted
Pending
Accepted Approved
36
36
36
0
13
13
13
0
6
4
4
2
0
0
0
TBD
80
68
68
12
19
19
19
0
154
140
140
14
Inorganic Materials Count on LAT M&P List
ACD
CAL
Elec
I&T
Mech
TKR
Total
Polymer and Composite Materials
SLAC IPO GSFC
Submitted
Pending
Accepted Approved
47
47
47
0
26
22
22
4
12
11
11
1
0
0
0
TBD
23
22
22
1
27
17
17
10
135
119
119
16
Polymer and Composite Materials Count on LAT M&P List
Source: LAT-DS-00405, “LAT Mechanical Materials and Parts List,” March 2003
LAT-PR-01278 Section 2
2-29
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
LAT 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
ACD
CAL
Elec
I&T
Mech
TKR
Total
Lubricants
SLAC IPO GSFC
Submitted
Pending
Accepted Approved
1
1
1
0
0
0
0
0
2
2
2
0
0
0
0
TBD
4
4
4
0
2
2
2
0
9
9
9
0
Lubricant Count on LAT M&P List
ACD
CAL
Elec
I&T
Mech
TKR
Total
Processes
SLAC IPO GSFC
Submitted
Pending
Accepted Approved
13
13
13
0
6
6
6
0
4
4
4
0
0
0
0
TBD
10
10
10
0
3
3
3
0
36
36
36
0
Processes on LAT M&P List
Source: LAT-DS-00405, “LAT Mechanical Materials and Parts List,” March 2003
LAT-PR-01278 Section 2
2-30
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Materials 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
ACD
CAL
Elec
I&T
Mech
TKR
Total
Materials Pending Approval
Lacking Needs
Tested
Material
Change
Total
Info for
Qual
for OutID is TBD
Material
Pending
Approval Testing
gassing
0
0
0
0
0
0
0
0
0
0
4
4
0
2
0
1
0
3
TBD
TBD
TBD
TBD
TBD
TBD
12
1
0
0
0
13
0
0
2
1
8
10
12
3
2
2
12
30
Materials Pending Materials Branch Approval
Source: LAT-DS-00405, “LAT Mechanical Materials and Parts List,” March 2003
LAT-PR-01278 Section 2
2-31
GLAST LAT Project
Mechanical Design Integration Peer Review, March 2003
Summary 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
LAT-PR-01278 Section 2
2-32