glast lat project september 15, 2006: pre-shipment review presentation 3 of 12 se overview 1 glast...
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SE Overview 1
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
GLAST Large Area TelescopeGLAST Large Area Telescope
LAT Pre-Shipment Review
Systems Engineering
Pat HascallSystems Engineering
Stanford Linear Accelerator Center
Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope
SE Overview 2
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
LAT System Engineering OverviewLAT System Engineering Overview
• Requirements Baseline Maintenance– Specifications– Interface Control Documentation– Waiver Requests (See Section 10)
• Design Baseline Maintenance– Design Documentation Configuration Management– Design Changes Since PER
• Requirements Verification Plan (See Section 5)
– Traceability to tests, analysis, inspection– Running Sell Process with GSFC Project Office
SE Overview 3
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Documentation StatusDocumentation Status
• The SE related documentation: see next chart (s)
– LAT Specification Current
– Traceability to verification complete
– Verification Cross Reference Matrix Released
– LAT Test Plan Released
– Three pending changes to LAT-S/C ICD: See later chart
– Several Waivers in Process: See NCRs and Waivers– One pending requirement update in 433-IRD-0001
• I&T documentation status: See I&T presentation
• QA documentation status: See QA presentation
No significant documentation liensNo significant documentation liens
SE Overview 4
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Documentation Status (continued)Documentation Status (continued)
• RFAs from previous reviews – See Systems Engineering Web site for dPDR, PDR, and
CDR RFA closures• http://www-glast.slac.stanford.edu/
systemengineering/RFAS/RFAS.htm– Two PER RFA’s open
• #1: Alignment Verification– Response: Updated response provided
• #8: NCR/Waiver Review for Unidentified Current and Residual Risks
– Response: LAT project/NASA review and update included in this package
SE Overview 5
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Key Documentation Key Documentation
Mission Level Documents433-SRD-0001: GLAST Science Requirements Document 433-IRD-0001: GLAST Science Instrument – Spacecraft Interface Requirements Document 433-SPEC-0001: GLAST Mission System Specification 433-OPS-0001: GLAST Operations Concept 433-MAR-0001: Mission Assurance Requirements (MAR) for GLAST LAT 433-RQMT-0005: GLAST EMI Requirements 433-ICD-0001: GLAST LAT-GBM Burst Interface Control Document1196 EI-Y46311: SC-LAT Interface Control Document 1196 EI-S46310: 1553 Interface Control Document LAT Level DocumentsLAT-SS-00010: LAT Performance Specification LAT-SS-00778: LAT Environmental Specification LAT-SS-00115: Mechanical Subsystem Specification (in final release cycle)LAT-SS-00715: TCS Performance Specification LAT-SS-00019: Trigger & Dataflow Subsystem SpecificationLAT-TD-00399 Software Requirements Specification LAT-SS-00016: ACD Subsystem Specification LAT-SS-00017: Tracker Subsystem Specification LAT-SS-00136: Power Subsystem Specification LAT-SS-00018: CAL Subsystem Specification LAT-MD-00446: LAT SVAC Plan LAT-MD-00408: LAT Performance Verification Plan LAT-MD-02730: LAT Performance and Operations Test Plan LAT-MD-07658: LAT Verification Cross Reference Matrix
SE Overview 6
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
SC-LAT ICD Pending ChangesSC-LAT ICD Pending Changes
ICN # Title Description Status
-096Unregulated Power Voltage
For shorts periods of time, the SC will be unable to provide the minimum 25V for the unregulated feeds. The voltage may get as low as 23V. GSFC review
-099 LAT IntegrationThis is an appendix to the ICD that is meant to capture agreements for Observatory I&T activities. Approved
-100 LAT ImpedanceIncorporate into ICD the as-measured LAT differential impedance.
Pending SC PRU Measurement
-109 LAT VCHP OvervoltageThe SC limits the voltage on the SIU and DAQ feeds but not on the VCHP feeds. In review
-111 MLI Interface Minor changes to the MLI interface, i.e. velcro size In sign off
– SC-LAT ICD EIY46311-000C is released–The table below lists pending changes
SE Overview 7
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Overview of Subsystem Changes Since PEROverview of Subsystem Changes Since PER
• Design Changes Flowed From LAT MRB Process– Changes incorporated in final design documentation– All changes consistent with LAT-SC ICD
• Residual Design Liens Against Flight Software discussed in FSW presentation
• Mechanical– Minor blanket modifications
• Flight Software– Boot code updated
SE Overview 8
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
LAT End Item Data PackageLAT End Item Data Package
• The LAT Project provides an EIDP consisting of the following documents, data, and other materials– LAT-level subsystem-level requirements specifications
• Acceptance test data packages for subsystems– Requirements verification plans and test plans– LAT-level test procedures and reports, and links to test execution
logs and records– Open nonconformance reports and waivers– Integration and test records
• Assembly and Inspection Data Sheets• Integration records: mate/demate, installation logs, material mix
records– EGSE and MGSE documentation
• All LAT project documentation is maintained in hardcopy and electronic form at SLAC– The EIDP is a subset
• EIDP posted on the Pre-Shipment Review Agenda Page:– http://www.slac.stanford.edu/exp/glast/flight/rdm/sasspreship/
lat_sasspreship_review.html
• EIDP is currently being populated
SE Overview 9
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Residual RisksResidual Risks
ID #Risk Rank
Risk DescriptionRisk Mitigation Status
SE - 011
Low
If individual tracker towers do not meet performance requirements due to manufacturing issues (e.g. wire bond breaks) then the LAT may not meet science requirements
•Reduced On Orbit temperature excursions
• Optimized placement of towers A/B based on individual tower performance
•Trending tracker efficiency/dead channels throughout integration testing
• No current concern for mission performance over life expected
Proj Mgt - 009 Low
If Tracker Noise Flares (NCR684), increase an order of magnitude and spread then some risk to overall tracker noise performance
• Monitor for occurrence• Verified no significant change during TVAC•Continue trend in Observatory Test
• Observed noise is an order of magnitude lower than a concern level and isolated
• No increased trend during system test to date
Elect - 005
Low
If spare GASU (AEM) FPGA failure (NCR897) is inherent in the design then mitigation on flight unit could impact schedule
• Complete part failure analysis •Survey of part failure records• Complete assessment of root cause
• Part failure analysis & survey complete
•Root cause identified, no known flight issue
SE Overview 10
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Residual Risks (Cont)Residual Risks (Cont)
ID #Risk Rank
Risk DescriptionRisk Mitigation Status
Elect - 006 Low
If SIU reboot (NCR 880) is an inherent design flaw then loss of data until reboot completed
• Completed existing data analysis• Additional diagnostics/data gathering plan in place
•Data gathering plan in place should another reboot occur
SE-014
Low
If ACD PMTs become noisy again (NCR626), then ACD ability to perform background rejection may be reduced
• More stringent PMT high voltage screening •All noisy tubes were replaced in the flight ACD• Flight PMTs are operated at voltages less than voltages that produced noise
• No new noisy PMTs have appeared after thousands of tube-hours of screening at high voltage•Conservative Wiebull prediction shows extremely low chance of potentially noisy PMTs making it through the screening.
Elec-007
Low
If the unused QCLK floating pins on PCI FPGA impacts part reliability then mission redundancy may be reduced
• Completed vendor analysis indicating no known failure mode or impact on reliability• Completed LAT analysis indicating no known failure analysis• Consider risk of grounding pins should alternative need to open box occurs
• GSFC Mission Office review and concurrence, no known risk at this time
SE Overview 11
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Residual Risks (Cont)Residual Risks (Cont)
ID #Risk Rank
Risk DescriptionRisk Mitigation Status
Elect - 009 Low
If EPU reboot (NCR 881) is an inherent design flaw then loss of data until reboot completed
• Completed existing data analysis• Additional diagnostics/data gathering plan in place
• Data gathering plan in place should another reboot occur
Elect - 011 Low
If EPU 0 reboot (NCR 902) is an inherent design flaw then loss of data until reboot complete0
• Completed existing data analysis• Additional diagnostics/data gathering plan in place
• Data gathering plan in place should another reboot occur
Elect-012
LowIf LATC Verify Errors (NCR855) re-occur on orbit then LAT will not execute science run until corrected
• Completed existing data analysis• Additional diagnostics/data gathering plan in place•Consider FSW changes to allow science run with these specific Errors
• No re occurrence reported since FSW 0-6-9
• Data gathering plan in place should another LATC verify error occur
SE Overview 12
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Residual Risks (Cont)Residual Risks (Cont)
ID #Risk Rank
Risk DescriptionRisk Mitigation Status
Elect - 014 Low
If EPU reboots (NCR 948) are an inherent design flaw then loss of data until reboot completed
• Completed existing data analysis• Additional diagnostics/data gathering plan in place
• Data gathering plan in place should another reboot occur
Elect - 015 Low
If EPU reboots (NCR 949) are an inherent design flaw then loss of data until reboot completed
• Completed existing data analysis• Additional diagnostics/data gathering plan in place
• Data gathering plan in place should another reboot occur
SE Overview 13
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Residual Risks (Cont)Residual Risks (Cont)
ID #Risk Rank
Risk DescriptionRisk Mitigation Status
Proj Mgt - 012 Low
If decision to conduct tracker environmental tests with non flight cable configurations (Waiver 433-0360) results in future failure then tracker redundancy may be compromised
• Tracker cables are redundant• Full CPT’s conducted in flight configuration•Trackers to be tested at LAT and Observatory Environmental tests
•No failures to date
•Continue to monitor thru test program
Proj Mgt - 014 Low
If Tracker flex cables/MCM’s fail that had failed coupons (Waiver 433-0367) then Tracker redundancy may be impacted
• Tracker cables/MCMs are redundant•Trackers to be tested at LAT and Observatory Environmental tests
• No failures to date
•Continue to monitor thru test program
Proj
Mgt-
018
Low
If finalization of FSW Science Algorithms is delayed or impacts LAT functional performance then Observatory Test Schedule could be impacted
•FSW build (B1.0) plan in place to add Science requirements
• New Science Algorithms do not impact established LAT performance
• Significant CPU/Memory margin to accommodate minor growth
•Plan to maximize early LAT runtime at SASS
•Well defined build planning with Proj Office involvement in change control
•TVAC eval of CPU peak performance indicate small (acceptable) temperature increase with worst case utilization
•Non interference LAT runtime planning in work
SE Overview 14
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
LAT Mass Properties LAT Mass Properties LAT Mass Properties Report LAT-TD-00564-12
LAT Mass Properties Summary Effective Date: 24-Apr-06Martin Nordby Print Date: 24-Apr-06
May-06Mass (kg) Estimate Alloc.
TKR 524.5 530.0 (kg) %
CAL 1381.7 1440.0 Parametric 21.4 0.8%ACD 281.6 295.0 Calculated 40.4 1.4%Mech 351.5 386.6 Measured 2727.2 97.8%Elec 242.5 240.0 Total 2789.0 100%Systems 7.1 8.0
LAT Total 2789.0 2899.6Rsrv/Margin 211.0Rsrv/Margin* 7.6%Allocation 3000.0* AIAA G-020 recommended min reserve = 3.8%Allocations per latest mass CCB on 3 Nov 2004
Center of Mass (mm)CMx -1.57 -20 < CMx < 20CMy -1.20 -20 < CMx < 20CMz -65.99 CMz < -51.2Ht off LIP 170.21 Ht < 185
Second Moment of Inertia (kg-m2)Ixx 1039.4 1400.0Iyy 996.8 1350.0Izz 1385.1 1580.0
Mass properties evaluated in LAT Coordinate System
Mass Estimate Breakdown
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
5Ju
l-05
Oct
-05
Jan-
06A
pr-0
6Ju
l-06
Oct
-06
Date
Mas
s (k
g)
125
150
175
200
225
250
275
300
Cen
ter
of
Ma
ss H
eig
ht
Ab
ov
e L
.I.P
. (m
m)
Mass Budget Review ThresholdTotal Allocated to S.S. LAT Mass EstimateCtr of Mass Est (off LIP)
I-PDR
I-CDR
I-SRR
294.9
I-PSRLAT ReserveLAT Margin 153.7
Prop
dPDR
Subsystem Allocation
CoM Ht off LIP
LAT Est Mass
Page Number 15
GLAST LAT Project September 15, 2006: Pre-Shipment Review
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LAT Power StatusLAT Power Status
7-Sep-06 Estimate PARA CALC MEAS SPEC
Item (Watts) (Watts) (Watts) (Watts) (Watts)
ACD 11.3 0.0 0.0 11.3 11.5
Tracker 159.2 0.0 0.0 159.2 160.0
Calorimeter 67.8 0.0 0.0 67.8 71.0
Trigger & Data Flow 297.3 0.0 0.0 297.3 327.5
Grid/thermal 26.2 0.0 0.0 26.2 35.0
Instrument Total 561.8 0.0 0.0 561.8 605.0
Instrument Allocation 650.0
% Reserve 15.7%LAT Power
400.0
450.0
500.0
550.0
600.0
650.0
700.0
Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06
Po
we
r -
Wa
tts
PDR7/30/02
I
CDR5/1/03
I
PSRR09/06
IGoals estimated using guidelines given in ANSI/AIAA G-020-1992 "Estimating and Budgeting Weight and Power Contingencies for Space Craft Systems"
PDR Reserve Was 15.2%CDR Reserve Was 13.4%
Goal for PSRR Reserve > 5%
PARA - Best Estimate based on conceptual design parametersCALC - Estimate based on Calculated power from detailed design documentationMEAS - Actual power measurements of components
SE Overview 16
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
LAT Power Status (Continued)LAT Power Status (Continued)
• Survival Power
Component Current Subsystem Power Estimates (W)
Alloc. PARA CALC MEAS Total Margin
On-Orbit Average Power Total1 278.00 0 0 211.3 211.3 31.6%
Regulated VCHP Power Total 58.00 0 0 44.5 44.5 30.3%
Unregulated Passive Survival Power 220.00 0 0 166.8 166.8 31.9%
1Power status reflects the LAT steady state orbit average. Numbers do not reflect transition into or out of survival mode, i.e. early orbit operations.
SE Overview 17
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
FSW Resource UsageFSW Resource Usage
Resource Total Available Current
Usage
Margin Factor
Source
EPU Boot EEPROM (SUROM)
256 kB 62 kB* 4* B0-6-11
SIU Boot EEPROM (SUROM)
256 kB 62 kB* 4* B0-6-11
EPU EEPROM 6 MB 0.59 MB 10 B0-6-11
SIU EEPROM 6 MB 0.73 MB 8.2 B0-6-11
EPU CPU cycles 200% in 2 EPUs 40% > 5 Estimate
SIU CPU cycles 100% in 1 SIU 25% 4 Estimate
EPU memory 128 MB 16-32 MB 4-8 Estimate
SIU memory 128 MB < 16 MB 8 Estimate
* Storing multiple copies (4 currently to use available memory) for risk mitigation
SE Overview 18
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Instrument Bandwidth ResourcesInstrument Bandwidth Resources
Resource Max Total BW limited
by Hardware
Max limited by SC-ground
transmission
Ave current BW at 10 KHz max
trigger rate*
Ave current BW at 2 KHz
nominal trigger rate*
Margin Factor
(for 10 KHz rate)
Detector to GASU-EBM 45 N/A 10 2 4.5
GASU-EBM to EPU-CPU 20 N/A 5 1 4
EPU-CPU to GASU-EBM 2.5 0.075 0.04* 0.02* 2
GASU-EBM to SIU-CPU 5 0.15 0.08* 0.015* 2
SIU-CPU to Spacecraft 5 0.15 0.08* 0.015* 2
EBM: Event-Builder Module
EPU: Event-Processing Unit
SIU: Spacecraft Interface Unit
• LAT communication, bandwidth (BW) in Mbyte/sec
* Present performance of event filter for EPU-CPU, still being optimized. Eventually the physics filter will be adjusted/loosened to take advantage of the max average bandwidh
SE Overview 19
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
Unit Run TimeUnit Run Time
• These unit run times start after the LAT was completely integrated and cover through the completion of the CPT after TV– Does not include integration testing– Does not include unit testing
SIU-P SIU-R GASU-P GASU-R EPU-P0 EPU-P1 EPU-R Towers ACD ACD HV1
ACD HV2
PDU-P PDU-R
1 949 0 949 0 949 949 0 949 949 949 0 949 02 0 541 0 541 0 541 541 541 541 0 541 0 5413 62 0 0 62 62 62 0 62 62 62 0 62 04 0 30 0 30 30 0 30 30 30 0 30 30 05 0 30 30 0 30 0 30 30 30 0 30 0 306 19 0 19 0 0 19 19 19 19 19 0 0 197 0 3 3 0 3 0 3 3 3 0 3 3 08 0 3 0 3 0 3 3 3 3 3 0 0 39 23 0 0 23 23 23 0 23 23 0 23 0 23
Totals 1053 608 1001 659 1097 1598 627 1661 1661 1033 628 1044 617
Config No.
LAT UNITS ON
SE Overview 20
GLAST LAT Project September 15, 2006: Pre-Shipment Review
Presentation 3 of 12
LAT System Engineering SummaryLAT System Engineering Summary
• Process for verification closure with GSFC in place• SE Review of LAT Environmental Tests and verification status
indicate ready to ship