Title: GLAST Large Area Telescope:
1GLAST Large Area Telescope LAT System
Engineering WBS 4.1.2 Dick Horn SLAC System
Engineering Manager Dhorn_at_slac.stanford.edu 650
926-8578
2Topics
- LAT System Engineering Overview D. Horn
- Design Review Summary
- Key System Performance Metrics
- Configuration Management And Technical Baseline
- Risk Management
- Cost Schedule Summary
- Requirements, Traceability Interfaces
- System FMEA/PRA/Reliability T. Thurston
- System Verification T Leisgang
3LAT System Engineering Overview
4Design Maturity Summary
PDR Delta Baseline Review
Subsystem CDR Peer Reviews
LAT Ready For S/C IT
Mature Stable Requirements Since SRR Interfaces
With Spacecraft Established and Reflected in CDR
Design
5PDR DPDR, Peer Review RFA Closure
- PDR RFAs Submitted, xx of 57 Closed
- Working with GSFC on residual issues
- Calorimeter to grid attachment
- EMI/EMC box level acceptance test
- dPDR RFAs Submitted, xx of 20 Closed
- No design drivers identified
- LAT Initial responses under review by GSFC
- Subsystem CDR Peer Review RFAs
Subsystem Number Of RFAs Status
ACD 19
Calorimeter 30
Electronics/FSW 26
Tracker 39
Mechanical 48
6LAT Mass Status
7LAT Power Status
8FSW Resource Usage Current Estimates
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 gt 6
SIU CPU cycles 100 in 1 SIU 25 4
EPU memory 128 MB 16-32 MB 4-8
SIU memory 128 MB lt 16 MB 8
Bandwidth instrument to EPU 20 MB/sec 5 MB/sec 4
Bandwidth EPU or SIU to SSR 5 MB/sec 40 kB/sec 112
Bandwidth CPU to CPU 2.5 MB/sec 20 kB/sec 125
9Key Science Performance Metrics
10Configuration Management
- LAT CM Defined By LAT MD-00068-01
- Major Supplier CM defined internally
- Key Subsystem Doc CM Transferred to LAT CM upon
Subsystem Delivery to LAT
11Management Plans
12Change Control Process
13Change Control Thresholds
14Risk Management
- LAT Risk Management Defined By
- LAT-MD-00067-03
- Parallel Process To GSFC .
- Continuous Process Across LAT
- Risk Ranked By Probability and Impact to
Technical, Cost Schedule
Risk Ranking
Impact
Low Risk (Selected Mitigation)
Moderate Risk (Selected Mitigation)
High Risk (Mitigation Required)
15Top Risks
ID Risk Rank Risk Description Risk Mitigation Mitigation Status
Moderate On track
Moderate On track
16System Requirements, Traceability Interfaces
17Specification Tree
18Requirements Development
19Requirements Traceability and Verification
Example of Flowdown from Science Requirements
20Requirements Traceability and Verification
Effective Area Requirement Flowdown
21Requirements Traceability and Verification
Effective Area Requirement Flowdown
22Requirements Traceability and Verification
Effective Area Requirement Flowdown
23Requirements Traceability and Verification
Example of Flowdown from Mission System
Specification
24Requirements Traceability and Verification
Example of Flowdown from Interface Requirements
Document
- Verification of this requirement includes
hardware and software components.
25Requirements Traceability and Verification
- Future Work
- Near term
- Incorporate all CCB-approved Level 2 and 3
changes in requirements document revisions (ECD
6/13/2003) - Bring DOORS database up-to-date with recently
released test plans (ECD 6/30/2003) - Release reports for all requirements verified by
analysis (ECD 7/31/2003) - Long term
- Prepare requirements verification table for level
2 and 3 requirements - Link requirements to test procedures (ECD June
2004) - Link requirements to test data packages (On-going
as tests are completed. ECD June 2005)
26LAT Interface Overview
Tracker (TKR) Interfaces Tracker (TKR) Interfaces
Structural Grid Ti flexure mount
Thermal Conductive Cu strap
Electrical Power, Data
Anticoincidence Detector (ACD) Anticoincidence Detector (ACD)
Structural Grid bolted joint, shear pins
Thermal Conductive bolted joint Radiative coupling
Electrical Power, Data
Electronics Electronics
Structural Stand-off to CAL Bolted stack
Thermal Thermal joint to X-LAT Plate
Electrical Power, Data
Calorimeter (CAL) Interfaces Calorimeter (CAL) Interfaces
Structural Grid pinned/bolted joint
Thermal Conductive bolted joint
Electrical Power, Data
SC Mount/ Solar Arrays SC Mount/ Solar Arrays
Structural Four-point mount to SC flexures
Thermal Isolated (SC Mount) Radiative (S/A)
Electrical Power, Data
TCS/X-LAT Plate/Radiators TCS/X-LAT Plate/Radiators
Structural Bolted/pinned joints
Thermal Heat pipes
Electrical Power, Data
LAT Overview
27Structural/Thermal Interface Overview
28Electrical Interface Overview
29Interface Documentation Status
30Internal LAT Interface Requirement Issues
31Key LAT-SC Interface Requirements 1/3
Requirement is being developed
32Key LAT-SC Interface Requirements 2/3
LAT complies with little margin. Change was made
to increase the SIU power allocation to 32W and
reduce the DAQ power allocation to 668W.
33Key LAT-SC Interface Requirements 3/3
34Key Open/Recent Interface Issues
35Key Open/Recent Interface Issues
36Summary
- Weekly Telecons and Frequent Splinter Meetings
have resulted in - LAT-SC ICD released
- TKR, CAL and ACD ICDs released and contain 0
TBXs - Electronics-LAT Mechanical/Thermal ICD near
completion and soon to be released - Interface Definition Drawings near release
- All key open interface issues to be resolved by
August 2003, most will be resolved in June 2003
37GLAST Large Area Telescope LAT
FMEA/PRA/Reliability Tim Thurston
SLAC thurston_at_slac.stanford.edu
38System FMEA/PRA/Reliability
Update To LAT Level From Tim Thurston
39GLAST Large Area Telescope System Engineering
Subsystem WBS 4.1.2 Tom Leisgang LAT Systems
Engineering Test Verification toml_at_slac.stanfor
d.edu
40Requirements Verification Process
A tested and certified instrument
41LAT Test Plan Organization
42LAT Performance Verification
43LAT Science Verification
44Subsystem Qualification Programs
45Subsystem Acceptance Test Program
46Performance Verification Thermal
47Performance Verification Dynamics
48Performance Verification Electronics
49LAT 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
50Systems Engineering
- DRAFT
- Cost/Schedule Summary
51CCB Actions Affecting 4.1.2
Change Request Description Status
LAT-XR-01395-01 Systems Engineering Manpower Approved 2.2M
52Budget, Cost, Performance
53Cost/Schedule Status
- Status as of February 28, 2003
Item In k
Budget at Complete 4,647
Budgeted Cost for Work Scheduled (a) 2,583
Budgeted Cost for Work Performed (b) 2,577
Actual Cost for Work Performed 2,880
Cost Variance -302 -11.7 of (b)
Schedule Variance -6 -.2 of (a)
54Manpower Plan
55Procurements
- Long-Lead Procurements
- Major Upcoming Procurements Near-Term (lt 4
months) - Orbital Network Engineering
- Stellar Solutions
- Major Upcoming Procurements Long-Term (gt4 months)
- Minor Upcoming Procurements
56Summary