GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
GLAST Large Area Telescope:
Gamma-ray Large
Area Space
Telescope
LAT System Engineering
WBS 4.1.2
Dick Horn
SLAC
System Engineering Manager
Dhorn@slac.stanford.edu
650 926-8578
Document: LAT-PR-01967
Section 7 Systems Engineering
1
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Topics
• LAT System Engineering Overview
–
–
–
–
•
•
•
•
D. Horn
Design Review Summary
Key System Performance Metrics
Configuration Management And Technical Baseline
Risk Management
Requirements, Traceability & Interfaces
System FMEA/PRA/Reliability
System Verification
Cost & Schedule Summary
Document: LAT-PR-01967
T. Thurston
T. Leisgang
D. Horn
Section 7 Systems Engineering
2
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT System Engineering Overview
Gamma-ray Large
Area Space
Telescope
Document: LAT-PR-01967
Section 7-1
Section 7 Systems Engineering
3
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
WBS 4.1.2 System Engineering
4.1.2 LAT System Engineering
D. Horn
System Integration & Audits
D. Lung/T. Thurston
Interface Develop. & Verif.
R. Bielawski
• FMEA/FTA/PRA
• Risk Management
• Ground System Interfaces
• System Reviews
• Internal ICD’s
• Spacecraft ICD
• Interface Verification
Configuration Mgmt
N. Cramar
• Document Control & Release
Document: LAT-PR-01967
Test Planning & Verif.
T. Leisgang/S. Sawyer
• LAT System Verification Plan
• Performance Test Planning
• Test Procedure Audits
• Test Discrepancy Resolution
Requirements Mgmt
W. Davis
• Requirements Management
• Configuration Item Data List
• System Metrics
Section 7 Systems Engineering
4
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Design Maturity Summary
Fiscal Years
2000
SRR
2001
2002
2003
2004
2005
PDR Delta
Baseline Review Subsystem CDR
Peer Reviews
PDR
Critical
Design
Review
PER
Begin
LAT I&T
2006
2011
LAT Ready
For S/C I&T
PreShip
Review
Ops.
Prelim. & Sys. Design
Final Design
Engr’g Models
Build & Test
Flight Units
FABRICATION PHASE
LAT I&T
Observatory
I&T
COMMISSIONING
PHASE
Mature & Stable Requirements Since SRR
Key Interfaces With Spacecraft Established and Reflected in CDR Design
Document: LAT-PR-01967
Section 7 Systems Engineering
5
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
PDR & DPDR, Peer Review RFA Closure
• PDR RFA’s Submitted, 43 of 57 Closed
–
Key residual issues:
• Calorimeter to grid attachment
• Closure of Tracker Engineering Model Results
• EMI/EMC box level acceptance test
• dPDR RFA’s Submitted, 17 of 20 Closed
–
–
Current Status of all
RFA’s Available at LAT
System Engineering
Website
No design drivers identified
LAT Initial responses under review by GSFC
• Subsystem CDR Peer Review RFA’s
Subsystem
Closed/Total
ACD
17/19
Calorimeter
12/30
Electronics/FSW
23/26
Tracker
17/39
Mechanical
19/48
I&T
17/21
Document: LAT-PR-01967
Subsystem talks will
address key open RFA’s
Section 7 Systems Engineering
6
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Mass Status
Document: LAT-PR-01967
Section 7 Systems Engineering
7
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Power Status
Item
5-Apr-03 Estimate
(Watts)
ACD
9.4
2.3
3.9
3.2
10.5
152.4
1.5
0.0
150.9
153.0
64.9
0.0
0.0
64.9
65.0
326.2
211.5
114.7
0.0
327.5
20.4
20.4
0.0
0.0
35.0
Instrument Total
573.3
235.7
118.5
219.0
591.0
Instrument Allocation
650.0
% Reserve
13.4%
Calorimeter
Trigger & Data Flow
Grid/thermal
CALC
(Watts)
MEAS
(Watts)
ALLOC.
(Watts)
PARA - Best Estimate based on
conceptual design parameters
CALC - Estimate based on
Calculated power from detailed
design documentation
MEAS - Actual power
measurements of components
Goals estimated using guidelines
given in ANSI/AIAA G-020-1992
"Estimating and Budgeting Weight
and Power Contingencies for Space
Craft Systems"
LAT-TD-00125-04
PDR Reserve Was 15.2%
Goal for CDR Reserve > 10%
Goal for PSRR Reserve > 5%
LAT Power
700
650
Power - Watts
Tracker
PARA
(Watts)
600
550
PDR
7/30/02
I
500
450
CDR
5/1/03
I
PSRR
9/05
I
400
Jan-99
Jan-00
Jan-01
Jan-02
Jan-03
Jan-04
Jan-05
Jan-06
Subsystem allocations have been reduced to CDR estimates to ensure
LAT system CCB action for future power growth
Document: LAT-PR-01967
Section 7 Systems Engineering
8
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
FSW Resource Usage Current Estimates
LAT-TD-1121-02
Resource
Total Available
Anticipated
Usage
Margin
Factor
EPU Boot PROM
256 kB
128 kB
2
SIU Boot PROM
256 kB
128 kB
2
EPU EEPROM
4 MB
1.5 MB
2.7
SIU EEPROM
8 MB
1.5-2.5 MB
3-5
EPU CPU cycles
200% in 2 EPUs
30%
>6
SIU CPU cycles
100% in 1 SIU
25%
4
EPU memory
128 MB
16-32 MB
4-8
SIU memory
128 MB
< 16 MB
8
Bandwidth – instrument to EBM
45 MB/sec
10 MB/sec
4.5
Bandwidth – EBM to CPU
20 MB/sec
5 MB/sec
4
Bandwidth – CPU to EBM
2.5 MB/sec
20 kB/sec
125
Bandwidth – EBM to SSR
5
40 kB/sec
125
Document: LAT-PR-01967
MB/sec
Section 7 Systems Engineering
9
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key Science Performance Metrics
Document: LAT-PR-01967
Section 7 Systems Engineering
10
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Management Plans
Document: LAT-PR-01967
Section 7 Systems Engineering
11
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Configuration Management
LAT CM Change Control Process
Need for
Change
Identified
RPE submits Change
Request (CR) for
manager approval.
Impact to
requirements, cost,
schedule?
NO
Level 4 change.
Change is implemented and
DCN is distributed to LAT team.
YES
LAT CM Elements
Level 2 or 3 change.
RPE submits a Change Request
(CR) for CCB screening.
GLAST Project Office
433-PROC-0001
CR is sent to the
Configuration Control
Board for approval.
GSFC
approval required?
NO,
Level 3
YES,
Level 2
Spectrum Astro
CR is sent to GSFC
for approval.
LAT Configuration
Management
LAT-MD-00068-01
If approved, the change is
implemented and the CR and DCN
are distributed to the LAT team.
LAT CM
LAT CM Defined By LAT MD-00068-01
Major Supplier CM
• Major Supplier CM defined internally
Tracker
SLAC/UCSC
LAT-MD-00068-01
ACD/GSFC
LAT-MD-00845-01
CAL/NRL
LAT-MD-01486-01
• Key Subsystem Doc CM Transferred to LAT
CM upon Subsystem Delivery to LAT
• Change Control Process In Place
Italy
Document: LAT-PR-01967
France
Section 7 Systems Engineering
12
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Change Control Thresholds
Document: LAT-PR-01967
Section 7 Systems Engineering
13
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Risk Management
Project Team
Assessments
Expert
Interviews
Lessons
Learned
FMEA/FTA
Consolidation by
PRM
Review by Risk
Review Board
Risk
Assessment
Networked
Schedules
Cost vs
Effectiveness
Development
of Mitigation
Strategy
Review by Risk
Review Board
Risk
Identification
Risk
Information
Database
Fault
Trees/Event
Trees
Networked
Schedules
Work
Accomplished
Performance
Margin
• Parallel Process To GSFC ….
• Continuous Process Across LAT
• Risk Ranked By Probability and Impact
to Technical, Cost & Schedule
Risk Ranking
Risk Analysis
5
4
3
2
1
Risk
Information
Database
(Watch Lists,
Contingency
Plans)
Risk
Planning,Mitigation
and Tracking
Mitigation
Activities
LAT Risk Management Defined By
LAT-MD-00067-03
13
11
9
7
5
16
14
12
10
8
1
2
19
17
15
13
11
3
Probability
22
20
18
16
14
25
23
21
19
17
4
5
Low Risk (Selected Mitigation)
Moderate Risk (Selected Mitigation)
Monitoring of
Project
Performance
by
Managers/Risk
Review Board
TPM
Charts
High Risk (Mitigation Required)
Corrective
Action
Document: LAT-PR-01967
Section 7 Systems Engineering
14
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Top System Risks
ID #
CAL004
Proj
Mgt 001
Proj
Mgt 002
Risk
Rank
Risk Description
Risk Mitigation
Status
•A higher CDE manufacturing rate is an
option to the French contract but may
present financial and technical risks.
The higher rate would deliver the later
modules on schedule.
• Current
top program
issue
High
•Delay in deliveries of flight CDEs
•Our French collaborators are in the
middle of a competitive procurement for
the industrial partner that will fabricate
all flight CDEs. The procurement
process must follow French law and is
potentially subject to the delay of
administrative reviews
•The selected industrial partner must
design and fabricate appropriate tooling,
develop controlled manufacturing
process, fabricate and qualify CDE
prototypes, and then fabricate 108 CDE
for the CAL Qual model by mid Sept,
2003
Moderate
•Inadvertent use of non-flight qualified
processes, parts or materials; results in
cost/schedule impact.
•EEE Parts Plan In-place. Material
Review Board. Preproduction readiness
reviews
• Processes
in place
•ASIC’s fail to meet requirements;
results in schedule impact
•Focused review & test. Margin for reruns protected where possible
•Individual risks Identified by subsystem
• Processes
in place
Moderate
Document: LAT-PR-01967
Section 7 Systems Engineering
15
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Top System Risks (continued)
ID #
SE-0010
Risk
Rank
Moderate
Risk Description
Inadequate End to End LAT test
simulation leads to undetected
H/W or S/W problem until at
observatory test or on orbit
Risk Mitigation
•Key early performance &
integration interface testing
through engineering model test
bed
•Early integration of Spacecraft
Simulator into development and
I&T
Status
•Evaluation of planned
functional & performance
tests to identify residual
risks (6/17/03)
•Finalizing details of S/C
Simulator (TBD)
•Audit test opportunities and
value (Airplane test, T/C Tests)
SE-0007
Moderate
Critical component failure post
LAT integration requiring deintegration impacting cost &
schedule
Document: LAT-PR-01967
•Extensive use of EM test bed
to support flight H/W & S/W
development
•Thorough qualification and
acceptance tests
•Pre planned I&T actions for deintegration
• Completed evaluation for
improving access (9/02)
• Qual & acceptance
planning in-place
•I&T developing
contingency plans
Section 7 Systems Engineering
16
GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
Document: LAT-PR-01967
CDR/CD-3 Review May 12-16, 2003
System Requirements, Traceability
& Interfaces
Section 7-2
Section 7 Systems Engineering
17
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Specification Tree
MAR
EMI Rqmts. Doc.
In Development
LAT IOC/MOC/
SSC Interface
Control
Documents
Mission System
Specification
433-SPEC-0001
Science
Rqmts
Mission
Rqmts
Interface
Rqmts
Mission Ground
System
Requirement
Documents
LAT-SC Interface
Requirements
Document
Interface
433-IRD-0001
Rqmts
Mission
Level 2a
Science
Requirements
Document
433-SRD-0001
TCS Performance
Specification
LAT-SS-00715
Trigger &
Dataflow Subsys.
Specification
LAT-SS-00019
TKR Subsystem
Specification
LAT-SS-00017
ACD Subsystem
Specification
LAT-SS-00016
Radiator Design
Specification
LAT-SS-00394
X-LAT Plate
Design
Specification
LAT-SS-01240
ACD Design
Specification
LAT-SS-00352
Grid Box Design
Specification
LAT-SS-00775
Document: LAT-PR-01967
LAT IOC
Performance
Specification
LAT-SS-00015
LAT-GBM
Interface Control
Document
Power
Subsystem
Specification
LAT-SS-00136
SAS
Subsystem
Specification
LAT-SS-00020
CAL Subsystem
Specification
LAT-SS-00018
LAT Flight SW
Specification
LAT-SS-00399
LAT Trigger
Specification
LAT-SS-00284
LAT Dataflow
Specification
LAT-SS-00285
LAT TKR Design
Specification
LAT-SS-00134
LAT Readout
Electronic
Specification
LAT-SS-00152
Tower Power
Supplies
Specification
LAT-SS-01537
LOF
Subsystem
Specification
LAT-SS-00021
SAS Design
Specification
LAT-SS-00505
CAL Design
Specification
LAT-SS-00210
LAT Operations
Facility
Specification
LAT-SS-01783
Section 7 Systems Engineering
LAT Subsystem
Level 3
Mechanical
Subsystem
Specification
LAT-SS-00115
LAT-SC Interface
Control Document
Design Specification
Level 4
LAT Performance
Specification
LAT-SS-00010
LAT
Level 2b
1553 Definition
LAT
Environmental
Specification
LAT-SS-00778
18
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Requirements Development
Level 2 Reqts
Peer Reviews
(Aug. 2000)
Level 2 Reqts
placed under
LAT CM
Line-by-line reviews
of LAT and IOC
Performance Specs
by Subsystem Mgrs,
Engineering and
Science Leads
Updates require
approval of LAT
change control board
Preliminary
Design Reviews
(Jan. & Jul. 2002)
Reqts. docs
imported and
linked in
DOORS
Level 4 Reqts
developed by
subsystems
Level 4 Reqts
placed under
subsystem CM
Subsystem design
specifications are
controlled at the
subsystem level.
Level 4 requirements
are managed and
tracked at subsystem
level.
Document: LAT-PR-01967
LAT System
Requirements
Review
(Sep. 2000)
Level 3 Reqts
Peer Reviews
(Mar.-Apr. 2001)
Top-level subsystem
performance
requirements were
reviewed by
Subsystem Mgrs and
LAT Engineering and
Science Leads
CCB changes,
document
updates and test
planning
Level 3 Reqts
placed under
LAT CM
Updates require
approval of LAT
change control board
Reqts. in
DOORS linked
to planned tests
and analyses.
Critical Design
Review
(May 12-16, 2003)
Impacts from changes are
flowed up or down as they
are identified.
Resulting Level 3 traceability to
verification plans is documented
in LAT-TD-02084-01
Section 7 Systems Engineering
19
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key Requirements Flow
Document: LAT-PR-01967
Section 7 Systems Engineering
20
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key Level 2 Requirements
Description
Doc./ Para.
LAT-SS-00010
5.2.1
5.2.2
LAT Instrument Performance Specification
Energy Range
The LAT shall measure gamma rays in the range of 20 MeV to greater than 300 GeV. The instrument shall have an
Effective Area > 300 cm 2 at 20 MeV, > 3000 cm 2 at 100MeV, and > 6400 cm 2 at 300 GeV.
Energy Resolution
5.2.3
The energy resolution of normal incidence gamma rays shall be < 50% for 20-100 MeV, < 10% for 100 MeV - 10
GeV, and < 20% for 10 - 300 GeV. Equivalent Gaussian 1 sigma.
The energy resolution for tracked gamma rays of greater than 60° incidence shall be better than 6% in the energy
range 10 to 300 GeV, with an effective area > 10% that of normal incidence.
Peak Effective Area
5.2.5
5.2.6
5.2.8
5.2.12
5.2.13
5.3.3
5.3.4
5.3.6
5.3.10.2
The Peak Effective Area of the LAT shall be greater than 8000 cm 2.
Single Photon Angular Resolution - On-axis at 68% Containment
For 100 MeV: better than 3.5° (conversion in front of tracker) and better than 6° (conversion in back of the tracker).
For 10GeV - 300 GeV: better than 0.15° (front of tracker) and better than 0.3° (back of tracker)
Single Photon Angular Resolution - On-axis at 95% Containment
Better than 3 times the single photon angular resolution at 68% containment.
Field of View
The field of view shall be greater than 2 steradians.
Background Rejection
LAT shall have a background rejection capability such that the contamination of the observed high latitude diffuse
flux (assumed to be 1.5 x 10-5 cm-2 s -1 sr-1) in any decade of energy ( > 100 MeV) is less than 10%, assuming a
photon spectral index of -2.1 with no spectral cut-off.
Dead Time
The dead time shall be less than 100 usec per event.
Science Data Interface
The SI shall output science data to the spacecraft via a LVDS data bus interface as specified in the SI/SC IRD.
(Includes data volume limit of 26 gigabits in 24 hours.)
Data Services
The SI shall communicate with the spacecraft via a serial command, telemetry, and data (CTDB) bus as defined by
MIL-STD-1553B as specified in the SI/SC IRD.
Mass
The mass of the SI shall be less than 3000 kg.
Average Power
The average power dissipation of the SI shall not exceed 650 W per orbit.
Document: LAT-PR-01967
Comply
Method
Y
T, A
Y
T, A
Y
T, A
Y
T, A
Y
T, A
Y
T, A
Y
T, A
Y
T, A
Y
T, A
Y
T, D
Y
T, D
Y
T
Y
T, A
Section 7 Systems Engineering
21
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Requirements Traceability and Verification
Example of Flowdown from Science Requirements
Science Requirements Document
Effective Area
LAT Level 2(b) Specification
LAT-SS-00010
5.2.3
ACD Level 3 Specification
LAT-SS-00016
Peak Effective Area
Tracker Level 3 Specification
LAT-SS-00017
Calorimeter Level 3 Specification
LAT-SS-00018
5.6 Mean Thickness
5.2 Gamma Ray Conversion
Efficiency
5.9 Low Energy Trigger Signal
5.8 False VETO due to Electrical
Noise
5.3 Converter Configuration
5.10 High Energy Trigger Signal
5.11.2 Fast VETO Signal
Latency
5.5 Geometric Area
5.11.3 Logic VETO Signal
5.11 Self Trigger
5.11.4 Logic VETO Signal
Latency
5.12 Data Noise Occupancy
5.11.5 Logic VETO Signal
Timing
5.11.6 Fast VETO Signal Width
5.11.7 Fast VETO Recovery
Time for Large Signals
5.11.9 ACD Trigger Primitives
Document: LAT-PR-01967
Section 7 Systems Engineering
22
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Requirements Traceability and Verification
Effective Area Requirement Flowdown
SRD Requirement
2
Effective Area > 8,000 cm
Maximum (as function of energy) effective area at normal incidence. Includes inefficiencies necessary
to achieve required background rejection. Effective area peak is typically in the 1 to 10 GeV range.
LAT Level 2b Requirement LAT-SS-00010
A map of the tiles that produce VETO signals shall be generated for each Level 1 Trigger
Acknowledge.
The map of VETO signals shall be latched by the time the ADC's conversions are completed.
Verification
SVAC Plan Measurement
S1 Fraction of
Reconstructed Photons
(Effective Area)
Verification
Interaction Analysis,
Shield/Blanket Analysis
CPT (LAT-TD-01112),
Step 19, 30
CPT (LAT-TD-01112),
Step 44
CPT (LAT-TD-01112),
Step 8
GARC Functional Test
5.11.5
The logic VETO map shall represent the state of all ACD discriminators at the time of the particle
passage (± 200 ns) causing the Level 1 Trigger Acknowledge.
CPT (LAT-TD-01112),
Step 8
5.11.6
The fast VETO output signal shall have a commandable width of 50 - 400 nsec, after 'de-glitching' on
2 successive clock pulses. The leading and trailing edges must be synchronous with clock pulses.
FREE Functional Test
(ACD-PROC-000051)
5.11.7
For a signal equivalent to 200 MIPs, the logic VETO signal shall be no longer than 10 ìs. (current
design will be < 5 usec).
FREE Functional Test
(ACD-PROC-000051)
5.2.3
5.6
5.8
5.11.2
5.11.3
5.11.4
2
The Peak Effective Area of the LAT shall be greater than 8000 cm .
ACD Level 3 Requirements LAT-SS-00016
The ACD, support structure, and micrometeorite shield shall absorb less than 6% of the incident
gamma radiation in the LAT field of view.
The false VETO signal rate due to noise shall result in a rejection of no more than 1% of triggered
gamma rays.
The fast VETO signal latency shall be commandable from 200-1600 ns after particle passage
Example from LAT-TD-02084-01, LAT Requirements Tracking Report
Document: LAT-PR-01967
Section 7 Systems Engineering
23
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Requirements Traceability and Verification
• Future Work
– Near term
• Incorporate all CCB-approved Level 2 and 3 changes in
requirements document revisions (ECD 6/30/2003)
– Long term
• Complete compliance verification table for level 2 and 3
requirements
– Link requirements to test procedures (ECD June 2004)
– Link compliance to test data packages & analysis reports
(On-going as tests & analyses are completed. ECD June 2005)
Document: LAT-PR-01967
Section 7 Systems Engineering
24
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key LAT Interface Overview
Tracker (TKR)
Anticoincidence Detector (ACD)
Structural
Thermal
Electrical
I&T
Structural
Thermal
Electrical
Grid bolted joint, shear pins
Conductive bolted joint; Radiative
coupling w/ TKR
3.3V, 28V; Data, Temp sensors,
S/W
Lift fixture, Electrical test stand
I&T
Grid Ti flexure mount
Conductive Cu strap
1.5V, 2.5V, 2.5VDig, 150V
Bias; Data, Temp sensors,
S/W
Lift fixture, Electrical test
stand
Electronics
Structural
Calorimeter (CAL)
Structural
Thermal
Electrical
I&T
Thermal
Grid pinned/bolted joint
Conductive bolted joint
3.3V, 3.3VDig,100V Bias;
Data, Temp sensors, S/W
Alignment Tool, Lift fixture,
Electrical test stand
Electrical
I&T
Stand-off to CAL; Bolted
stack; Cabling
Thermal joint to X-LAT
Plate
27-29V Regulated, Data,
S/W
Test bed
GBM
Structural
Thermal
Electrical
Spacecraft
Structural
Thermal
Electrical
I&T
Four-point mount to SC flexures,
Two-point pinned struts for each
radiator
Isolated (SC Mount, Radiator
struts); Radiative (S/A)
27-29V Regulated, 25-35V
Unregulated, MIL-STD-1553B,
Analog and digital sensors,
LVDS, EMI/EMC, High speed
serial science data
Grid perimeter ring, Radiator
handling fixture, Radiator lift
fixture, Purge, LAT test point
Document: LAT-PR-01967
I&T
Cabling
None
LVDS, 1553
Telecommands
None
TCS/X-LAT Plate/Radiators
Structural
Thermal
Electrical
I&T
Bolted/pinned joints
Heat pipes, Heaters
27-29V Regulated, 25-35V Unregulated;
Temp sensors, S/W
Radiator handling fixture, Radiator lift
fixture, X LAT Plate lift fixture, Electrical
test stand
Section 7 Systems Engineering
25
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Structural/Thermal Interface Overview
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
Htr Sw
Box
Radiator
Solar
Array
CAL
EMI Skirt
Htr Sw
Box
Rad
Mnt
Bkt
X-LAT Plate
Spacecraft
Solar
Array
LV Payload Attach Fitting
Document: LAT-PR-01967
Section 7 Systems Engineering
26
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Spacecraft-LAT Electrical Interface
4 Voltages
SC
4 Temperatures, 8 Voltages
Grid and Antifreeze
Survival Heaters
C&DH
4 Voltages
32 Temperatures
LAT
+Y
Science Data
Command & Telemetry
SIU
SC PDU
SC PRU
25V – 35V
28V ± 1V
LPDU
SIU
Timing
8 Discrete Controls
DAQ
+X
VCHP
4 Discrete Monitors
6 Temperatures, 12 Voltages
EGSE
22 Temperatures
Burst
Trigger
4 Voltages
LVDS
1553
Power
Signal
Document: LAT-PR-01967
GBM
Note: Redundancy not shown
Section 7 Systems Engineering
27
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Internal LAT Electrical Interfaces
Heater Switch
Box (x2)
25-35 V
Heaters (VCHP,
Antifreeze, Grid)
Power
Command
Data
3.3V, 28V
Monitors
GASU
ACD BEA
Elec
24 Temp, 48 Volt
1.5V, 2.5V, 2.5V Dig,
150V Bias
TKR Tower
Module (x16)
28+/-1 V
8 Temp
PDU
Radiator Mount
Brackets
Document: LAT-PR-01967
TKR
CAL Module
(x16)
TEM (x16)
16 Temp
VCHP Heaters
ACD
3.3V, 3.3V Dig,
100V Bias
CAL
Mech
194 Temp
Temp Sensors
(VCHP, Radiator,
Grid, X-LAT,
Antifreeze, CAL
Baseplate)
100 Temp
Temp Sensors
(VCHP, Radiator,
Grid, X-LAT,
ACD)
Section 7 Systems Engineering
EMI Shield
28
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key TKR-LAT Interface Requirements*
Section
Number
6
6.2.3
7.2
8
8.1
9
11
Description
Comply Method
Mechanical Interface
TKR Tower Center of Gravity
The maximum X/Y center of gravity offset from the geometric center of a Tracker module is +/- 10 mm.
The maximum Z center of gravity position is 245 mm where Z=0 is at the top of the grid.
Structural Limit Loads and Environmental Requirements
The Tracker to Grid interface shall meet the structural limit loads and environmental requirements of the LAT
Environmental Specification.
Dimensions
Static Stay-Clear Dimensions
TKR components shall stay within the stay-clear volume described in LAT-DS-00851.
Thermal Interface and Heat Transfer
The TKR shall meet the temperature requirements in the LAT Environmental Specification.
The LAT Grid and the LAT thermal control system shall maintain the TKR modules within the temperatures shown in
the LAT Environmental Specification.
Power
Maximum power power consumption of the Tracker subsystem is 155W.
Y
Y
T
T
Y
A, T
Y
I
TBR
A,T
TBR
A,T
Y
T
A=Analysis, D=Demonstration, I=Inspection, T=Test
* TKR-LAT Mechanical and Thermal ICD, LAT-SS-00138 and TKR-LAT Electrical ICD, LAT-SS-00176
Document: LAT-PR-01967
Section 7 Systems Engineering
29
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key CAL-LAT Interface Requirements*
Section
Number
6
6.3.2
6.3.3
6.5
7
7.1
8
8.6
10
Description
Comply Method
Mechanical Interface
CAL Module Mass Variation
The maximum allowable mass variation among CAL modules shall be +/- 2 kg.
CAL Module Center of Gravity
The maximum X/Y center of gravity offset from the geometric center of a Cal module is +/- 10 mm.
The maximum Z center of gravity position from the CAL-grid interface is 116 mm.
Structural Limit Loads and Environmental Requirements
The CAL Base Plate to Grid interface shall meet the structural limit loads and environmental requirements of the
LAT Environmental Specification.
Dimensions
Static Stay-Clear Dimensions
CAL components shall stay within the stay-clear volume described in LAT-DS-00233.
Electrical Interface
Power Consumption
Maximum power draw for the combined digital and analog 3.3V interfaces is 1.25 watts per AFEE card.
Maximum power draw for the PIN photodiode bias supply is 0.001 Watts.
Thermal Interface and Heat Transfer
The CAL shall meet the temperature requirements in the LAT Environmental Specification.
The LAT Grid and the LAT thermal control system shall maintain the CAL modules within the temperatures shown in
the LAT Environmental Specification.
Y
I
Y
Y
T
T
TBR
A, T
Y
I
Y
Y
T
T
Y
A, T
Y
A,T
A=Analysis, D=Demonstration, I=Inspection, T=Test
* CAL-LAT Mechanical, Thermal and Electrical ICD, LAT-SS-00238
Document: LAT-PR-01967
Section 7 Systems Engineering
30
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key ACD-LAT Interface Requirements*
Section
Number
6
6.3.2
6.5
7
7.1
8
8.6
10
Description
Mechanical Interface
Center of Gravity
The maximum X/Y center of gravity offset from the geometric center of the ACD shall be +/- 10 mm.
The Z-axis CG position shall be less than 340 mm where Z=0 is the top of the grid.
Structural Limit Loads and Environmental Requirements
The ACD to Grid interface shall meet the structural limit loads and environmental requirements of the LAT
Environmental Specification.
Dimensions
Static Stay-Clear Dimensions
The ACD subsystem components shall stay within the stay-clear volume described in LAT-DS-00309.
Electrical Interface
Power Consumption
The worst-case total consumption of the 12 HVBSs shall be less than 5.0 W at 29V, maximum bus voltage.
Thermal Interface and Heat Transfer
The ACD shall meet the temperature requirements in the LAT Environmental Specification.
The LAT Grid and the LAT thermal control system shall maintain the ACD within the temperatures shown in the LAT
Environmental Specification.
Comply
Method
Y
Y
T
T
Y
A, T
Y
I
Y
T
Y
A,T
Y
A,T
A=Analysis, D=Demonstration, I=Inspection, T=Test
* ACD-LAT Mechanical, Thermal and Electrical ICD, LAT-SS-00363
Document: LAT-PR-01967
Section 7 Systems Engineering
31
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key Electronics-LAT Interface Requirements*
Section
Number
6
6.6
8
8.1
9
10
Description
Comply Method
Mechanical Interface
Structural Limit Loads and Environmental Requirements
The Electronics to LAT interfaces shall meet the structural limit loads and environmental requirements of the LAT
Environmental Specification.
Dimensions
Static Stay-Clear Dimensions
Electronic modules shall stay within the stay-clear volume described in LAT-DS-01630.
Thermal Interface and Heat Transfer
The Electronic modules shall meet the temperature requirements in the LAT Environmental Specification.
The LAT X-LAT Plate and the LAT thermal control system shall maintain the Electronic modules within the
temperatures shown in the LAT Environmental Specification.
Thermal Control System
Meet the functional requirements of the LAT Thermal Control System.
Y
A, T
Y
I
TBR
A,T
TBR
A,T
Y
T
A=Analysis, D=Demonstration, I=Inspection, T=Test
* Electronics-LAT Mechanical and Thermal ICD, LAT-SS-01794
Document: LAT-PR-01967
Section 7 Systems Engineering
32
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key Open Internal LAT Interface Issues
INTERFACE KEY OPEN ISSUES
Tracker
Validating TKR-Grid
copper strap thermal
design.
Calorimeter Validating CAL Base
Plate to Grid structural
design.
ACD
None
Electronics Validating X-LAT Plate to
Electronics box thermal
joint design.
Document: LAT-PR-01967
STATUS
 Detailed design complete.
 Testing is underway.
RESOLUTION
ECD
TKR to complete thermal testing as
8/1/03
part of Engineering Model test plan
closure.
7/15/03
 Focused on a pinned design
 Perform design trades.
implemented with bolts to the
Grid.
 Preliminary analysis and
 Perform analyses and tests to
tests indicate design has
verify design has positive
negative margins.
margins.
 Other design options have
 Maintain large design
been identified and are under
margins for joint load capability.
investigation.
 Thermal design developed
using vel-therm and parallel
thermal paths.
 Preliminary analysis
confirms design meets interface
temperature requirements.
 Finalize detailed interface
design.
7/15/03
 Engineering Model testing to
validate design.
Section 7 Systems Engineering
33
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Internal LAT Interface Compliance Issues
Doc/Section
Number
LAT-SS-00138,
9.1.2
Description
Comply Method
TKR-LAT Mech,Therm ICD - Thermal Interface and Heat Transfer
The LAT and the LAT thermal control system shall maintain the tracker modules within the temperatures
shown in the LAT Environmental Specification, LAT-SS-00778.
LAT-SS-00238,
6.5.1.2
LAT-SS-01794,
9.1.2
TBR
A, T
The CAL-Grid interface design shall meet the interface limit load requirements as specified in the LAT
Environmental Specification, LAT-SS-00778.
Electronics-LAT Mech,Therm ICD - Thermal Interface and Heat Transfer
TBR
A, T
The LAT and the LAT thermal control system shall maintain the electronic box base plates within the
temperatures shown in the LAT Environmental Specification, LAT-SS-00778.
TBR
A, T
CAL-LAT ICD - CAL-Grid Interface Loads at CAL Tabs
A=Analysis, D=Demonstration, I=Inspection, T=Test
Document: LAT-PR-01967
Section 7 Systems Engineering
34
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key LAT-SC Interface Requirements 1/3
Section
Number
4
4.2
4.4.1
4.4.2
4.5.1
4.6
5
5.2
5.3
Description
Comply Method
Mechanical Interface
Size
The LAT with integrated radiators shall not exceed the envelope defined in the LAT-SC IRD.
The LAT shall not exceed the dynamic envelope shown in Appendix A.
Mass, Center of Mass, and Moments of Inertia
The launch mass for the LAT shall not exceed 3000 kg as defined in the LAT-SC IRD.
Requirement is
The LAT center of mass shall not exceed the values defined in the LAT-SC IRD.
The LAT mass moments of inertia shall not exceed the values defined in the LAT-SC IRD. being developed
Modes and Stiffness
The LAT fixed base stiffness, fixed at the interface points, shall produce a first mode frequency greater than 50 Hz.
LAT Sensor Mounting
The LAT shall be mounted at four locations as shown in the LAT-SC IRD.
Cable Routing and Connector Locations
The LAT shall locate the external connectors to the SC harness as shown in Appendix A.
Thermal Interfaces
Thermal Conduction
The total worst-case conductive heat exchange between the SC and LAT through the interface locations at the Grid
and all cables between the LAT and SC shall not exceed ±5W.
Thermal Radiation
The LAT thermal design shall accommodate the radiative heat leak through the MLI, assuming SC average
temperatures varying between -10°C and +50°C.
Y
Y
I
A, T
Y
Y
TBD
I
T
A
Y
A, T
Y
I
Y
I
Y
A, T
Y
A, T
A=Analysis, D=Demonstration, I=Inspection, T=Test
Document: LAT-PR-01967
Section 7 Systems Engineering
35
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key LAT-SC Interface Requirements 2/3
Section
Number
Description
Electrical Interface
Electrical Connections
The interface connectors between the LAT and the SC harness are shown in Table 6-1.
Detailed pin assignments shall be as shown in Appendix B.
6.3.1.1 Average Operational Power
During normal operations the LAT shall not exceed an orbit average of 650 W of regulated power.
6.3.1.2 Average Survival Power
During survival operations the LAT shall not exceed an orbit average of 270 W from the following sources: A.50W Regulated VCHP heater power. B.220W - Unregulated passive survival heater power.
6.3.1.3 Peak Power
The LAT shall consume no more than 758 W for less than a total of 10 minutes per orbit.
The SIU shall not exceed a maximum of 32 W.
The DAQ shall not exceed a maximum of 668 W.
The VCHP reservoir heaters shall not exceed a maximum of 58 W.
The passive survival heater power shall not exceed a maximum of 560 W.
6.3.2
Power Distribution
The LAT shall tolerate instantaneous removal of power without damage or degradation to itself or the SC.
6.3.2.2.1 Regulated Feed Exclusivity
The LAT shall tolerate, without damage or degradation to itself or the SC, primary and redundant power feeds that
are active at the same time.
6.3.2.2.1 Unregulated Feed Exclusivity
The LAT will passively control the manner by which the survival heater circuit is closed.
6.4
Command and Data Handling
The analog telemetry signals shall be block redundant between the SC and LAT as shown in Figure 6-3.
All other signals shall be cross-strapped as shown in Figure 6-4.
Comply
Method
Y
Y
I
T
Y
A, T
Y
A, T
Y
Y
Y
Y
Y
A,
A,
A,
A,
A,
Y
T
Y
A
Y
D
Y
Y
T
T
6
6.2
A=Analysis, D=Demonstration, I=Inspection, T=Test
Document: LAT-PR-01967
Section 7 Systems Engineering
36
T
T
T
T
T
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key LAT-SC Interface Requirements 3/3
Section
Number
Description
High Speed Serial Science Data
The LAT shall limit science data generation to no more than 26 gigabits in any single 24-hour period.
The maximum signal frequency of any one interface signal shall 8.25 MHz.
The high speed Serial Data interface transmitters and receivers shall use LVDS drivers and receivers compatible
with IEEE 1596.3SCI LVDS and be compatible with ANSI/TIA/EIA 644-1996 LVDS standards.
6.4.3
Discrete Electrical Interfaces
The LAT is redundantly allocated the following discrete command and telemetry interfaces: A. 1 Discrete Time
Pulse B. 8 Discrete Control Commands. B. 4 Discrete Monitor Telemetry C. 96 Passive Analog Telemetry.
6.4.3.1
Discrete Time Pulse
The PPS signal shall be accurate to ±1.5 usec when the SC is receiving Global Positioning System (GPS) updates.
The PPS signal shall not drift more than ±1 usec in any given 100 second period when GPS signals are unavailable.
The PPS signal characteristics shall be of LVDS type.
6.4.3.2.1 Digital Control Circuit and Signal Characteristics
The digital control signal characteristics shall be of LVDS type.
6.4.3.3.1 Bi-Level Circuit and Signal Charateristics
The digital monitor signal characteristics shall be of LVDS type.
7
Flight Software
7.2
Command and Telemetry Formats
All 1553 message protocol formats shall be as documented in the GLAST 1553 Protocol Document.
9
LAT Ground Support Equipment (GSE) Interface
9.1
Mechanical Ground Support Equipment (MGSE)
The LAT contractor shall provide all MGSE for support, lifting and handling of LAT hardware.
The LAT MGSE shall not exceed the allowable volume shown in Appendix A.
9.2
Electrical Ground Support Equipment (EGSE)
The LAT test point connector(s) shall be located as shown in Appendix A.
LAT EGSE shall interface to SC EGSE using an Ethernet connection.
12
Environment
The LAT shall demonstrate environment compliance.
The LAT shall be capable of withstanding flight environments and test levels.
Comply
Method
Y
Y
T
T
Y
D
Y
D
Y
Y
Y
T
T
D
Y
D
Y
D
Y
D
Y
Y
A, D
I
Y
Y
I
D
Y
Y
A, T
A, T
6.4.1
A=Analysis, D=Demonstration, I=Inspection, T=Test
Document: LAT-PR-01967
Section 7 Systems Engineering
37
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Key Open External LAT Interface Issues*
INTERFACE KEY OPEN ISSUES
Spacecraft Radiator mechanical
interface details need to
be finalized.
STATUS
Radiator mount concepts
exchanged.
RESOLUTION
 GSFC to clarify IRD
requirement.
 Evaluate impacts to current
design.
LAT evaluating MOI request.
ECD
6/1/03
Spacecraft
Development of new LAT
Moment of Inertia
requirement.
Spectrum Astro requests using
LAT worst case MOI estimate vs
LAT allocation.
Spacecraft
Potential Radiator static
stay-clear envelope
growth.
 Evaluate potential solutions
and assess impacts.
6/1/03
 Connector locations
indentified.
 Hold frequent splinter
meetings until issue is resolved.
8/1/03
 Detailed harness routing
being worked.
 Status issue at weekly
interface meeting.
 Issue identified as part of
CDR work.
6/1/03
 Potential design options
have been identified. Most
solutions affect only LAT while
others affect the SC.
Spacecraft
Finalize harness definition
and routing.
*Face-to-face technical interchange meeting is scheduled for May 21 & 22 to discuss
remaining interface issues.
Document: LAT-PR-01967
Section 7 Systems Engineering
38
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Interface Documentation Status
Document
LAT-SC Interface Control Document (Spectrum Astro Managed Document)
1196 EI-Y46311-000
1553 Bus Potocol Document
1196 EI-S46310-000
GBM-LAT Interface Control Document
433-ICD-0001
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-00309-3: ACD-LAT Interface Definition Drawing
LAT-SS-00363-5: 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, Elec Interface Control Document
Document: LAT-PR-01967
Status
Released 25 Apr 03
Released 25 Apr 03
Final draft out for review
In signature cycle
Released 13 Mar 03
Released 22 Apr 03
Released 28 Apr 03
First draft in-progress
Released 14 Apr 03
Released 27 Jan 03
First draft in-progress
First draft out for review
Section 7 Systems Engineering
39
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Summary
• Weekly Telecons and Frequent Splinter Meetings
have resulted in:
–
–
–
–
–
LAT-SC ICD released
LAT-SC 1553 ICD released
TKR, CAL and ACD ICD’s released and contain 0 TBX’s
Electronics ICD w/ 5 TBX’s in review
Interface Definition Drawings released or near release
• Complete Implementation of LAT-GBM ICD
• All key open interface issues to be resolved by
August 2003
Document: LAT-PR-01967
Section 7 Systems Engineering
40
GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
CDR/CD-3 Review May 12-16, 2003
System Engineering
LAT FMEA/PRA/Reliability
Section 7-3
Tim Thurston
SLAC
thurston@slac.stanford.edu
Document: LAT-PR-01967
Section 7 Systems Engineering
41
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
Instrument Reliability Target:
RLAT  .85 for 5 year Mission Life
Instrument Element Reliability Targets (Established 05/2001)
RCAL
 .96
RTKR
 .96
RACD
 .96
RT&DF
 .96
RTML/STRU 
RCAL
Document: LAT-PR-01967
RTKR
.99
RACD
RT&DF
RTML/STRU
Section 7 Systems Engineering
42
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
LAT Instrument Reliability Block Diagram
TEM
TEM-PS
15 of 16
CAL
TEM
TEM-PS
15 of 16
RCAL = .9776
TKR
RTKR = .9668
EPU
BEA
TDA
AEM
GASU
SIU
MMS/MLI
AEM
Standby
11 of 12
94 of 96
RACD = .9568
STRU
PDU
EPU
GASU
Standby
SIU
Standby
RT&DF = .9884
PDU
2 of 2
Standby
EPU
Standby
2 of 3
TML
RTKR = .989
Document: LAT-PR-01967
RLAT = .882
Section 7 Systems Engineering
43
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
Reliability Calculations
Assumptions/Methodology
– Both Mil-HDBK-217F and vendor provided data are being used for the of
failure rates estimates.
– LAT level reliability analysis extracted some component reliability
numbers from element level reliability reports. Because of slightly
different view of reliability relationships and partitioning, LAT level results
vary slightly from reliability stated in element reliability reports.
– All reliability numbers normalized to 30 °C ambient using Mil-HDBK-217F
derating factors. The conservative factor is 1.5x improvement per 10 ° C
reduction.
– Massively redundant detections components, CAL and TKR, allowed to
degrade up to 10%, ACD detection components allowed to degrade 2 of 96,
Tower modules allowed to degrade to 15 of 16, and ACD BEA allowed to
degrade to 11 of 12. All degradations expected to be within science
performance margins.
– Some passive elements such as resistors and wires are not included in
the model. Failure rates for these elements are considered extremely low.
Document: LAT-PR-01967
Section 7 Systems Engineering
44
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
• CAL Module Reliability Block Diagram
CAL Power Feed
CAL Signal Feed
CAL AFEE
CAL Power Feed
CAL Signal Feed
CAL AFEE
CAL Power Feed
CAL Signal Feed
CAL AFEE
CAL Power Feed
CAL Signal Feed
CAL AFEE
CAL Power Feed
CAL Signal Feed
CAL AFEE
CAL Power Feed
CAL Signal Feed
CAL AFEE
CAL Power Feed
CAL Signal Feed
CAL AFEE
CAL Detector Element
43 of 48
CAL Detector Element
43 of 48
CAL Power Feed
CAL Signal Feed
CAL AFEE
RCAL(x) = .99964
Document: LAT-PR-01967
Section 7 Systems Engineering
45
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
Fault Tree Analysis – LAT-TD-01757-01
Rev 24,
Tower Electronic Module Power Supply Fault Tree
(L-TPS)
11 Mar. 2003
Page 10 of 13
Rev
24,
Tower Electronic Module Fault Tree
11 Mar. 2003
(L-TEM)
Page 9 of 13
Rev
24,
Spacecraft Interface Unit Fault Tree
11 Mar. 2003
(L-SIU)
• FTA’s completed on EPU’s, ACD, CAL,
TKR, STR, TML, GASU’s, PDU’s,
SIU’s, TEM’s, & TEM/PS’s
Page 7 of 13
• ~160 fault elements/components
• MMS & MLI are the only single point
failures identified. Probability of failure
is not realistic
(L-PDU)
Global-Tirgger/ACD-EM/Signal Distribituion Unit
(GASU) Fault Tree
Page 5 of 13
(L-GAS)
Rev 24,
11 Mar. 2003
Loss of GASU System Function
C-12, GAS-INS
Electronic Processing Unit Fault Tree
Page 4 of 13
(L-EPU)
Loss of EPU Sytem Function
C-5, EPU-INS
• No other single point failures without
ground contingency – (Software)
Loss of EPU
Loss of EMI Shielding
Loss of EPU S/W Function
Loss of GASU/EPU Comm.
C-26, STR-EPU/SIU/GAS
L-EPU-07
L-EPU-01
EPU Backplane Failure
(EPU Redundant - 2 of 3)
L-EPU-02
EPU SI Board Failure
(EPU Redundant - 2 of 3)
L-EPU-03
Loss of Electronics Bay Cooling
C-33, TML1- PDU,SIU,GAS,EPU
GASU/EPU Connector/Cable
Failure (Open)
L-EPU-05
EPU LC Board Failure
(EPU Redundant - 2 of 3)
L-EPU-04
Loss of EPU Power
C7, GAS-EPU
EPU Malfunction
EPU RAD750 Board Failure
(EPU Redundant - 2 of 3)
• Most components multiple redundant
Power Distribution Unit/SC Power
Bus Fault Tree
Rev 24,
11 Mar. 2003
Page 6 of 13
Rev 24,
11 Mar. 2003
EPU Code
Failure
Software Contingency
Reload Filter software
EPU Power-On Chip Failure
(EPU Redundant - 2 of 3)
GASU/EPU Connector/Cable
Failure (Short to ground/signal)
(EPU Redundant)
L-EPU-14
L-EPU-06
Loss of EPU Power Feed
C-9, PDU-EPU
Failure Mode & Effects Analysis -
PDU/EPU Power Feed
Connector/Cable Failure (open)
L-EPU-09
PDU/EPU Power Feed Conn./
Cable Failure (Short to ground/
signal) (EPU Redundant)
L-EPU-08
Legend
- OR Gate
LAT-TD-00374-01

- SUM Gate
- AND Gate
• ~ 800 failure modes identified
Failure Consequence
(connection with other
FTA sheets)
Ground Contingency
EPU/PS PolyFuse Failure
(EPU Redundant)
L-EPU-15
EPU/PS Connection
Failure (Open)
L-EPU-11
EPU 5.0V PS Failure
(EPU Redundant - 2 of 3)
L-EPU-13
EPU 3.3V PS Failure
(EPU Redundant - 2 of 3)
L-EPU-12
EPU/PS Conn. Failure (Short to
ground/signal) (EPU Redundant)
L-EPU-10
Non-Redundant Failure
Non-Redundant Failure
within Redundant System
Redundant Failure
Non-LAT Hardware
failure
Failure Consequence
Ref. To: LAT-SS-00010 L-II(b)
Graceful Failure
Consequence
Failure Consequence &
Propagation
• No severity category 1 failure modes
• One element to watch w/severity category 2 failure
mode
• Four elements to watch w/ failure mode severity
category of 2R, Two elements to watch w/ severity
category of 2MR
Document: LAT-PR-01967
Section 7 Systems Engineering
46
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
LAT-TD-02083-01 (Draft)
• Likelihood estimates made for all fault
sequences with failure mode
categorization of 1, 2, 2R, 2MR
• PRA watch list provided with fault
sequences prioritized from most likely to
least likely.
• PRA watch graphically summarized in a
5x5 risk matrix.
Probability
of
Severity
Occurrence Category Mitigating Actions
Falls within mission reliability requirements
0.01000
2
Probability
Redundancy design in electronics and PMT's yields reliability
of 2R
Severity
ACD system
that falls within mission reliability requirements
0.03350
Component
Occurrence Category
Mitigating
Actions
Redundancy
design yields
reliability that falls within mission
EPU system
reliability
requirements
0.00740 0.00990
2R
No
action, design optimized to meet ACD tile failure rate.
MMS
2
Redundancy
design
yields reliability
that falls
within
mission
Circuit
redundancy
in conjunction
with
cabling
redundancy,
SIU system
reliability power
requirements
0.00400
2R
redundancy
Mission
1 > Pf >.1
0/0
0/0 and thermal
0/0control, meets
0/0 0/0
0/0 system0/0
Redundancy
design
yields
reliability
that
falls
within
mission
Requirements
PDU Circuit
0.06120
2R
PDU system
reliability SIU
requirements
0.00193
2R
module redundancy in conjunction with cabling
TKR/TEM/TEM-PS
Redundancy
design yields
reliability
that falls
mission
redundancy,
power
redundancy
andwithin
thermal
control, meets
0/0
.1 >2MR
Pf >.01 reliability
0/0
3/4 0/4 0/0
system SIU Rad750 Board
requirements
0.03320 0.04860
Mission
system0/0
Requirements0/0
2R
CAL/TEM/TEM-PS
Redundancy
reliability
falls within
SIU design
moduleyields
redundancy
in that
conjunction
withmission
cabling
system
reliability redundancy,
requirementspower redundancy and thermal control, meets
0.02240
2MR
Redundancy
design
yieldsRequirements
reliability that falls within mission
Mission
system
SIU LC Board
0.01970
0/0
.01 > Pf >.001 2R
0/0
0/0
0/0
1/20 3/3 1/1
TML system
reliability SIU
requirements
0.01000
2MR
module redundancy in conjunction with cabling
Elements
MMS/MLI
SIU SI Board
SIU Backplane
Probability of Occurance (Mission Success)
Probablistic Risk Assessment –
redundancy, power redundancy and thermal control, meets
Mission system Requirements
Failure Unlikely - No
0.01370
known failure 2R
mechanism, large
margins
0/0
0/0
0/3
1/116
2/9 0/7
SIU module redundancy
in conjunction
with cabling
0.00764
Failure
not Credible 2R
Specific mitigation
action
0/2
5
No Effect
Elem./Comp.
0/0
0/0
0/0
0/0
0/0
4
3
2MR 2R
2
Loss of nonDegraded
Loss of Science
critical function Mission (meets (Does not meet
a) not needed,
minimum
minimum science
b) backup
science
Mission)
available
mission)
Severity Category - Consequence of Failure
Limited Life Item Analysis LAT-MD-00551-02
• No limited life items identified
within the 5-year design life
Document: LAT-PR-01967
0/0
redundancy, power redundancy and thermal control, meets
Mission system Requirements
Section 7 Systems Engineering
47
0/0
1S 1R
1
Total loss of
mission
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
Probability of Occurance (Mission Success)
Probabilistic Risk Assessment/FMECA Summary
1 > Pf >.1
0/0
0/0
0/0
0/0
0/0
0/0
0/0
.1 > Pf >.01
0/0
0/0
0/0
2/4
1/4
0/0
0/0
.01 > Pf >.001
0/0
0/0
0/0
1/20
3/3
1/1
0/0
Failure Unlikely - No
known failure
mechanism, large
margins
0/0
0/0
0/3
1/114 2/11
0/7
0/0
Failure not Credible Specific mitigation
action
0/2
0/0
0/0
0/0
0/0
5
No Effect
Element/Component
0/0
0/0
4
3
2MR 2R
2
Loss of nonDegraded
Loss of Science
critical function Mission (meets
(Does not meet
a) not needed, b)
minimum
minimum science
backup available science mission)
Mission)
1S 1R
1
Total loss of
mission
Severity Category - Consequence of Failure
Document: LAT-PR-01967
Section 7 Systems Engineering
48
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
Probabilistic Risk Assessment – Element Watch List
Elements
MMS/MLI
ACD system
EPU system
SIU system
PDU system
TKR/TEM/TEM-PS
system
CAL/TEM/TEM-PS
system
TML system
Probability
of
Severity
Occurrence Category Mitigating Actions
Falls within mission reliability requirements
0.01000
2
Redundancy design in electronics and PMT's yields reliability
that falls within mission reliability requirements
0.03350
2R
Redundancy design yields reliability that falls within mission
reliability requirements
0.00740
2R
Redundancy design yields reliability that falls within mission
reliability requirements
0.00400
2R
Redundancy design yields reliability that falls within mission
reliability requirements
0.00193
2R
Redundancy design yields reliability that falls within mission
reliability requirements
0.03320
2MR
Redundancy design yields reliability that falls within mission
reliability requirements
0.02240
2MR
Redundancy design yields reliability that falls within mission
reliability requirements
0.01000
2MR
Document: LAT-PR-01967
Section 7 Systems Engineering
49
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
Probabilistic Risk Assessment – Component Watch List (1 of 2)
Component
MMS
PDU Circuit
SIU Rad750 Board
SIU LC Board
SIU SI Board
SIU Backplane
Probability
of
Severity
Occurrence Category Mitigating Actions
No action, design optimized to meet ACD tile failure rate.
0.00990
2
Circuit redundancy in conjunction with cabling redundancy,
power redundancy and thermal control, meets Mission system
Requirements
0.06120
2R
SIU module redundancy in conjunction with cabling
redundancy, power redundancy and thermal control, meets
Mission system Requirements
0.04860
2R
SIU module redundancy in conjunction with cabling
redundancy, power redundancy and thermal control, meets
Mission system Requirements
0.01970
2R
SIU module redundancy in conjunction with cabling
redundancy, power redundancy and thermal control, meets
Mission system Requirements
0.01370
2R
SIU module redundancy in conjunction with cabling
redundancy, power redundancy and thermal control, meets
Mission system Requirements
0.00764
2R
Document: LAT-PR-01967
Section 7 Systems Engineering
50
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
System FMEA/PRA/Reliability
Probabilistic Risk Assessment – Component Watch List (2 of 2)
Probability
of
Severity
Component
Occurrence Category Mitigating Actions
Circuit redundancy in conjunction with cabling redundancy,
power redundancy and thermal control, meets Mission system
Requirements
AEM Circuit
0.00522
2R
Circuit redundancy in conjunction with cabling redundancy,
power redundancy and thermal control, meets Mission system
Requirements
GASU Circuit
0.00437
2R
EPU module redundancy in conjunction with cabling
redundancy, power redundancy and thermal control, meets
Mission system Requirements
EPU Rad750 Board
0.04860
2MR
EPU module redundancy in conjunction with cabling
redundancy, power redundancy and thermal control, meets
Mission system Requirements
EPU LC Board
0.01970
2MR
EPU module redundancy in conjunction with cabling
redundancy, power redundancy and thermal control, meets
Mission system Requirements
EPU SI Board
0.01370
2MR
CAL Module redundancy, power distribution, and redundant
readout yields CAL system that far exceeds reliability target
CAL AFEE Board
0.01100
2MR
Document: LAT-PR-01967
Section 7 Systems Engineering
51
GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
CDR/CD-3 Review May 12-16, 2003
System Engineering
Test Verification Planning
Section 7-4
Tom Leisgang
LAT Systems Engineering
Test & Verification
toml@slac.stanford.edu
Document: LAT-PR-01967
Section 7 Systems Engineering
52
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Requirements Verification Process
SPECIFICATIONS
Test Plans
GLAST Project
433-SPEC
433-SRD
433-IRD
433-MAR
433-RQMT
Procedures
T-VAC
SV&C
IPVP
LAT-MD-00466
LAT-MD-00488
Test
Report
Funct
Test
Report
CPT
EMI
TKR
CAL
LAT IIB
LAT-SS-00010
LAT-SS-00778
Results
Test
Report
Dynamics
Test
Report
ACD
Thermal
Survey &
Alignment
Mech
T&DF
LAT III
LAT-SS-00016
LAT-SS-00017
LAT-SS-00018
LAT-SS-00019
LAT-SS-00020
LAT-SS-00021
LAT-SS-00115
LAT-SS-00136
LAT-SS-00715
Analysis
Report
Dynamics
Flt S/W
EMI/EMC
Analysis
Report
Analysis
Report
Weight &
CG
Parse into
DOORS
Identify
Rqt.
Link to
Verification
Correllate
Results
Create Verification Matrix
Requirements Traceability
LAT Systems Engineering
A tested and certified instrument
Document: LAT-PR-01967
Section 7 Systems Engineering
53
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Test Plan Organization
LAT Instrument Performance
Verification Plan
LAT-MD-00408
T. Leisgang
Subsystem Test
Plans
LAT Performance &
Operation Test Plans
LAT Integration & Test Plan
LAT-MD-01376
E. Bloom
LAT Mechanical Integration
LAT-PS-00676
E. Gawehn
L. Wai
Tracker Tower Test Plan
LAT-TD-00155
Calorimeter Test Plan
Component
Aliveness Tests
Subsystem
Integration Tests
LAT-SS-00262
ACD Test Plan
LAT Limited
Performance
Tests
ACD-PLAN-000050
Thermal S/S Test Plan
LAT
Comprehensive
Performance
Tests
No Number
LAT Operational
Performance Tests
LATTrigger &
Datflow Test Plan
LAT-TD-00296
SUI
TEM
PDU
EP
GASU
L. Wai
LAT Contamination Control
LAT-MD-00404
Plan
E. Gawehn
J. Cullinan
M-GSE
LAT-MD-01462
Facilities
LAT-MD-01386
LAT Instrumentation Plan
LAT-MD-00890
M. Lovellette
W. Davis
E-GSE Development
M. Huffer LAT-MD-01533
LAT Survey & Alignment
L. Wai
LAT-MD-01586
LAT Survey Plan
LAT-TD-00895
M. Nordby
L. Wai
Mechanical Weight & CG
LAT-MD-01598
L. Wai
E. Gawehn
Dynamics Tests
No Number
M. Lovellette
E. Gawehn
Mechanical S/S Test Plan
LAT-SS-00493
LAT Flight Software Test
Plan
LAT-TD-00786
E. Gawehn
LAT Handling
&Transportation Plan
LAT-MD-00452
LAT-MD-00649
LAT Dynamics Test Plan
LAT-MD-01196
M. Lovellette
Y Ismael
Electrical Performance Tests
LAT-MD-01055
L. Wai
Thermal Tests
LAT-MD-0xxxx
M. Lovellette
E. Gawehn
LAT EMI Tests
LAT-MD-01838
M. Lovellette
Instrument Calibration
LAT-MD-01587
E. Do e Couto E Silva
LAT Thermal Test Plan
LAT-MD-01600
M. Lovellette
J. Wang
LAT EMI/EMC Test Plan
No Number
M. Lovellette
T. Leisgang
LAT SV&C Test Plan
LAT-MD-00446
E. Do Couto E Silva
T. Leisgang
LAT Beam and Particle
Test Plans
LAT-MD-0440
G. Godfrey
EGSE Workstation &
Software Validation Plan
LAT-MD-01533
R. Claus
Document: LAT-PR-01967
Section 7 Systems Engineering
54
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Performance Verification
LAT
Integration
Tower
Integration
Observatory
Integration
LAT Test
TKR
CAL
Grid
Integrate
TKR/CAL &
TEM's with
Grid
E
A
TEM/PS
O
F
Survey
E
EPU
C
C
F
A
Integrate
E-Boxes
w/ Grid
M Survey (2)
EMI/EMC
Thermal Vacuum
Environmental Tests
L Balance
C
Cycling
C M
L
M
C
Survey
LAT
Integration
SIU
Weight
PDU
GASU
L Sine Vibe
Sine Burst
O Survey
Htr Switch Box
EMI Shield
L
Install
Radiators
Weight & CG
O
Final
L
C
O M Survey
C
Thermal
Vac
L C M
Remove
Radiators
Modal
survey
Integrate
EMI Skirt, Htr
F
switch boxes
E
C
C
L Acoustic
Ship to
SLAC
ACD
E
X-LAT Plate
F
Integrate
ACD
Ship to
NRL
C
Integrate
F
X LAT Plate
E
M Survey
O
C
Store
LAT
Survey
L
Mechanical
Fit-Checks
@ Spectrum Astro
@NRL
Ship
to SA
Radiators
E
Electrical
InterfaceTests
A
Aliveness
Tests
Survey:
Document: LAT-PR-01967
Functional
Tests
F
O
Optical
L
M
Muon
Limited
Performance
C
Comprehensive
Performance
v3 CDR 4/21/03
Section 7 Systems Engineering
55
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT End to End System Verification
A B
LAT System Verification
Engineering Models
Qualification Units
Calibration Units
Integrated LAT
Final Verification
– By correlated analysis
•
2
TKR
CAL
TEM
CAL
TEM
CRU
CAL
Event
Processor
Event
Builder
SSR
TEM
14
TKR
CAL
TEM
15
TKR
CAL
TEM
16
TKR
CAL
TEM
Science Verifications
–
–
–
–
•
TEM
Front End @ Subsystem 3
TKR
T&DF In Test Bed
4
TKR
Integrated LAT @ I&T
System Throughput in Test Bed
• Uses event simulators
• Man-made events
•
CAL
Global
Trigger
GASU
Command / Response Unit
–
–
–
–
TKR
Command / Response Unit
•
1
SIU
TCU
Event
Processor
Spacecraft
Interface
Simulator
Discretes
SIU
TCU
Event
Processor
AEM
ACD
Subsystem
Test Bed
PDU
I&T
and
Test Bed
I&T
1553
DataBus
Risk
– Event Processing @ orbital
rates/distribution—not checked
Document: LAT-PR-01967
Section 7 Systems Engineering
56
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Science Verification
Science Verification
Calibrations
Particle tests


Engineering
Model
Qual Modules
Calibration
Unit
LAT
Flight LAT
TKR
All
Cal
All
ACD
Pedestals(L)
Detection Effcy.
High Threshold
Detect.
Document: LAT-PR-01967
SLAC ES-A
Positrons 1-45 Gev
Photons
tagged 100-1000 Mev
Brems >20Mev-1000 Mev
Protons 12Gev
Van de Graaff
Tracker
Efficiency
Alignment
SSD,Ladder
tray,tower
inter-tower
Tracker
Si Strips

noisy

dead
t
threshold
LAT
Accuracy
Dead Time
 Effective Area
 Absolute energy
 Energy Resolution
 Angular Distributions
on and off axis
 Bacground Rejection
 Monte Carlo Simulation
Validation
LAT
Alignment
Calorimeter
Light Yield
Scintillat. Effcy
Pedestals (L)
Energy Range (L)
Elex. Gain
Integ. Non;Inearity
Diff. Non;Inearity
Light Asymetry
Light Attenuation
(17.6 MeV  )
Van de Graaff
(17.6 MeV  )
Section 7 Systems Engineering
57
Cosmic Rays on the Ground
Reconstruction Software
Charged Track
reconstruction effcy.
  Conversion
point & effcy.
 Absolute Energy
on and off axis
 CAL Effcy. for track
 Effcy. for track w/ACD hits
 Monte Carlo Simulation
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Subsystem Qualification Programs
Qualification Test Sequence
VIBRATION
THERMAL
TRR
I/F
Random
LPT
Thermal
Vacuum
CPT
CPT
I/F
LPT
LPT
Humidity/
Storage
CPT/LPT
CPT
C
C
Sine
L
C
L
L
L
L
L
L
L
EMI/EMC*
C
L
C
C
EMI/EMC*
CPT
LPT*
RFU
Shock**
**As required
FINAL
*EMI/EMC Tests may be performeed anywhere within the flow
Document: LAT-PR-01967
Section 7 Systems Engineering
58
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Subsystem Acceptance Test Program
Acceptance Test Sequence
TRR
I/F
Random
LPT
I/F
CPT
Thermal
Vacuum
CPT
BurnIn
CPT
VIBRATION
Document: LAT-PR-01967
Thermal
CPT/LPT
CPT
RFU
FINAL
Section 7 Systems Engineering
59
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Performance Verification: Thermal
Qual
Proto-flight Acceptance
LAT
OBS
OBS
4 Cycles T/V& T-Bal
LAT
4 Cycles T/V& T-Bal
Cables
Tracker
4 Cycles
T/V
Calorimeter
4 Cycles
T/V
Document: LAT-PR-01967
X-LAT
Plates
EMI
Shield
Radiators
TBD Cycles
T/V & T-Bal
ACD
4 Cycles
T/V& T-Bal
Tracker
12 Cycles
T/V& T-Bal
Grid Box
Electronics
4 Cycles
T/V
Calorimeter
12 Cycles
T/V& T-Bal
Electronics
12 Cycles
T/V& T-Bal
Section 7 Systems Engineering
60
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Performance Verification: Mechanical
OBS
Shock
S
LAT
LAT
Acceptance
S
A
Weight
Cg
A
Modal
SB
Cables
Tracker
Proto-flight
R
S Sine
Calorimeter
R
X-LAT
Plates
EMI
Shield
Electronics
R
ACD sub assy
S
SB
R
A
Radiators
S
ACD
SB
R
shell + BFA
S
R A
SB
Tracker
Qual
KEY
SB
S
SB
SineBurst
Document: LAT-PR-01967
SB
Calorimeter
R
R Random
SB
R
Electronics
S
SB
R
Grid Box
Static Load
A Acoustic
Section 7 Systems Engineering
61
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Qual
Acceptance
LAT
Performance Verification: Electronics
Power
Operational
Performance
EMI
RE,RS,CE,CS
Power
Limited
Performance
EMI
CE(cm)
CS(cm)
Power
Full
Performance
EMI
Document: LAT-PR-01967
Full Suite
I/F Verification
Isolation Pwr Dist
Hi-Pot Cmd. Dist
Performance
Aliveness
Aliveness
I/F Verification
Performance
Aliveness
Functional
Comprehensive
Full Suite
I/F Verification
Full Suite
Performance
Aliveness
Functional
Comprehensive
Section 7 Systems Engineering
62
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Performance Verification: Flight
Software
Supported
Hardware
Target
Processor
LAT
Software
Flight LAT
Qualification
Formal
Qualification
Test
System
Module/
Pkg Test
Unit/
Component
Test
Interfaces
 Spacecraft
EM-1

Event Filters
DAQ Support
 AEM Configuration
 AEM Event Acquisition
 Multiple Tower Support
 Multiple TEM Support
Operation
 Mode Transitions
 Engineering
 Safe Mode
Housekeeping
 File Mgt.
Interfaces
 LCB Command/Response
 LCB Event Acquisition
DAQ Support
Event Data
 Format
 Export
 TKR


TKR/CAL/TEM Configuration
TKR/CAL/TEM Status
Calibration


CAL Chg injection
TKR Chg injection
Document: LAT-PR-01967
 CAL
 Event Filters
Housekeeping
 Tower

TEM

Low Rate Science
Multiple Towers
Multiple TEMS
GASU
CRU
EBM
AEM
GEM
1 CPU
SIU
Health, Status & Safety
Attitude
Time
SIU
EPU
1 Tower
1 TEM
1 CPU
SIU
Boot
Boot
CMD Processing
CMD Distribution
LAT Configuration
EPU
Derived TLM Mgt.
Software Watchdog
Instrument Physics
Calibration & Diagnostics
Test Bed
EM-2
1553
Telemetry
Command
Event Data
 Marker Events
 ACD
EPU
Boot
CMD Processing
Configuration
TLM Mgt
Section 7 Systems Engineering
63
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Verification Summary
• All LAT subsystems and LAT Instrument have complete
requirements verification
• All MAR test requirements are performed and verified
• All Science Requirements are verified
• Systems Engineering has a “closed loop” requirements
verification process in place
Document: LAT-PR-01967
Section 7 Systems Engineering
64
GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
Document: LAT-PR-01967
CDR/CD-3 Review May 12-16, 2003
Cost/Schedule Summary
Section 7-5
Section 7 Systems Engineering
65
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
CCB Actions Affecting 4.1.2
Change Request #
Description
Status
LAT-XR-01395-01
Systems Engineering
Manpower
Approved $1.8M
LAT-XR-01752-02
SLAC/HEPL Labor
Escalation Rates
Approved -$16K
Document: LAT-PR-01967
Section 7 Systems Engineering
66
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Budget, Cost, Performance
Budget vs Actuals vs Performance
DOE + NASA Project Expenditures
4.1.2 System Engineering
$M, Then-Year Dollars
8
4
Actual Commitments
ACWP
BCWP
BCWS+ Planned Commitments
BCWS
0
. .
. .
. .
FY00
Document: LAT-PR-01967
. .
FY01
. .
. .
. .
. .
FY02
. .
. .
. .
. .
. .
FY03
. .
. .
. .
FY04
. .
. .
. .
. .
. .
. .
FY05
Section 7 Systems Engineering
67
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Cost/Schedule Status
•
Status as of March 31, 2003:
Item
In k$
Budget at Complete
6,453
Budgeted Cost for Work Scheduled (a)
3,049 (a)
Budgeted Cost for Work Performed (b)
3,049 (b)
Actual Cost for Work Performed
3,029
Cost Variance
20
0.7% of (b)
Schedule Variance
0
0% of (a)
Document: LAT-PR-01967
Section 7 Systems Engineering
68
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Summary
• Independent Technical Peer Reviews have been completed
– Open issues identified
– Closure plans in work (see Subsystem detailed talks)
•
•
•
•
•
•
Configuration Management Processes in place
Key metrics established
Continuous Risk Management process in place
LAT System Interfaces are established and under CCB Control
LAT FMEA and Fault Tree Analyses baselined
Verification planning and oversight in place
Document: LAT-PR-01967
Section 7 Systems Engineering
69