GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
ISOC CDR, 4 August 2004
GLAST Large Area Telescope:
Instrument Science Operations Center
WBS: 4.1.B
Critical Design Review
Outline & Agenda
Bill Craig
Stanford Linear Accelerator Center
bcraig@slac.stanford.edu
650-926-2983
LAT-PR-04500
Section 1.0
1
GLAST LAT Project
ISOC CDR, 4 August 2004
Outline







Overview of Technical Approach &
Objectives
Requirements
Detailed Design
Ops Scenarios
Tools and Architecture
Build Process & Schedule
Management, Cost and Risks
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Section 1.0
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GLAST LAT Project
ISOC CDR, 4 August 2004
Agenda
8:30
8:35
9:10
9:35
10:10
10:40
11:00
11:30
12:00
12:40
13:00
13:30
14:30
14:45
15:00
15:15
15:30
16:00
16:30
1.
2.
3.1
3.2
3.3
3.4
4.1
4.2
5.
6.
7.
8.
LAT-PR-04500
Introduction and committee charge (Rackley)
Overview (Craig)
Requirements (Martin)
Commanding, Health and Safety Design (Bator)
Flight S/W and Testbed Design (Fisher)
Break and optional tour of LAT testbed
Performance Verification & Optimization Design (do Couto e Silva)
Science Data Products and Science Analysis Software (Dubois)
Lunch Break
Ops planning and interfaces (Bator Digel)
Ops Scenarios (Bator)
Software Architecture (Culp)
Network and H/W architecture (Dubois)
RFA Status (Bator)
Break
Management, Cost Schedule & Risks (Craig/Martin)
Agenda Schedule Reserve/General Discussion of Remaining Issues
Committee executive session
Adjourn
Section 1.0
3
GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
ISOC CDR, 4 August 2004
1.0 Overview: Technical
Approach & Objectives
Bill Craig
Stanford Linear Accelerator Center
bcraig@slac.stanford.edu
650-926-2983
LAT-PR-04500
Section 1.0
4
GLAST LAT Project
ISOC CDR, 4 August 2004
Review History

IOC Peer Design Review
August 2001

LAT PDR/Baseline Review
January 2002

Delta PDR/Baseline Review
July 2002

LAT CDR/CD3
May 2003

ISOC Peer Review (PDR)
March 2004
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GLAST LAT Project
ISOC CDR, 4 August 2004
Review Purposes
 At the 1st ISOC Peer Review (March ‘04) a number of RFA’s
were generated, primarily …..
 The purpose of this peer review is to establish that the ISOC
design is at a CDR-level: The detailed design — including
schedule — is largely in place.
 The Ground System Design Review (8/18-19) will build on the
individual peer reviews of the ground system elements and
interfaces between those elements.
 The materials for this review may be found at:
http://www-glast.slac.stanford.edu/ioc/
Ground system RFAs may be issued by the peer review panel
and GLAST-related personnel in attendance, specifically for
LAT ISOC areas.
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GLAST LAT Project
ISOC CDR, 4 August 2004
The GLAST Mission
LAT
GBM-NaI
GBM-BGO
LAT (> 100 MeV, 1year)
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GLAST LAT Project
ISOC CDR, 4 August 2004
GLAST Instruments, Spacecraft
 Gamma-ray Large Area Space Telescope (GLAST)
— successor to CGRO instruments EGRET and BATSE.
 The Large Area Telescope (LAT) — GLAST’s main instrument
The LAT is a NASA-DOE collaboration with foreign
contributions.
PI: Peter Michelson (Stanford & SLAC)
 The GLAST Burst Monitor (GBM) — GRB context instrument
The GBM is a MSFC-German collaboration.
PI: Chip Meegan (NSSTC)
 Spacecraft will be built by Spectrum-Astro.
 Scheduled launch is February 2007, into low earth orbit.
 Minimum mission is 5 years, with a goal of 10+ years!
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GLAST LAT Project
ISOC CDR, 4 August 2004
Large Area Telescope (LAT)
The LAT is a pair conversion telescope.
– A -ray is converted to an e+e- pair in one of 16 tungsten planes.
– The leptons are tracked by 19 pairs (X-Y) of silicon strip planes.
– The silicon strips and 8 planes of CsI “logs” measure the energy.
– Plastic anti-coincidence scintillator tiles provide first line of
defense against charged particles.
Tracker—tungsten and
silicon strip planes
Anticoincidence Detecto
Calorimeter—CsI logs
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GLAST LAT Project
ISOC CDR, 4 August 2004
LAT Performance Characteristics
 Energy Range: < 20 MeV to > 300 GeV
 E/E < 10% on axis for 0.1–10 GeV.
 Peak effective area ~ 10000 cm2
 FOV ~ 2.4 sr (½ peak Aeff at 52 off axis)
 1 angular resolution < 3.5° @ 0.1 GeV, < 0.12° @ 10 GeV
 Only a few events of the ~ 300 s-1 events telemetered to Earth
will be photons.
 Deadtime: ~ 20 s
 In normal, scanning operation GLAST will survey the sky; thus
most data will be taken at different angles to the LAT.
Large field of view and large effective area mean that the LAT will be
> 30  more sensitive than EGRET.
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GLAST LAT Project
ISOC CDR, 4 August 2004
LAT & GBM Spectral Coverage, FOV
LAT FOV
GBM FOV
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GLAST LAT Project
ISOC CDR, 4 August 2004
Observations
 GLAST can point “anytime, anywhere:”
–
The orientation of the Sun relative to solar panels and radiators is a
physical constraint, but does not affect pointing flexibility.
–
Observing efficiency dictates keeping the Earth out of the central
part of the field-of-view (FOV).
 Two basic observing modes:
–
Survey mode—the LAT scans the sky continuously. For uniform
exposure over short time periods, the spacecraft will rock every orbit
~ 30º about the zenith direction perpendicular to the orbital plane.
–
Pointed mode—the LAT points at a source.
•
Also, the LAT may point autonomously, e.g. in response to a GRB
alert.
 The LAT FOV is very large and source fluxes are low. Therefore,
survey mode will usually be the most efficient mode to build up
exposure over the sky.
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GLAST LAT Project
ISOC CDR, 4 August 2004
Data Levels
 Level 0—the cleaned-up telemetry: packets are time-ordered;
repeated packets are removed; packet accounting information
recorded
 Level 1—data processed by the instrument teams and ready
for astrophysical analysis. LAT events are calibrated,
reconstructed, characterized as photon/non-photon, and
described physically {energy, arrival time, origin, …}.
 Level 2—results of routine data analysis, e.g., timing analysis
and spectral fits.
 Level 3—compendia of Level 2 data, e.g., catalogs.
 Ancillary data—the astrophysical analysis will require, e.g., a
model of the diffuse background, and a database of pulsar
ephemerides.
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GLAST LAT Project
ISOC CDR, 4 August 2004
Mission Phases
 The mission has 3 phases:
– Phase 0—the ~ 60 day checkout period after launch
– Phase 1—the 1 year sky survey while instrument teams
–
calibrate their instruments. Except for observations of
transients, the data are restricted to the instrument teams
and a small number of guest investigators.
Phase 2—the rest of the mission until deorbit. The GI
program drives the observations; however, simulations
predicate that survey mode is still expected to predominate.
 Yearly GI cycles; Cycle 1 will coincide with Phase 1.
– Cycle 1: approximately one dozen GIs will be selected.
– Subsequent cycles: approximately 100 GIs per cycle.
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GLAST LAT Project
ISOC CDR, 4 August 2004
LAT ISOC’s Role in the GLAST GDS
LAT-PR-04500
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GLAST LAT Project
ISOC CDR, 4 August 2004
LAT ISOC View of Ground System
GLAST
TDRS
LAT
Collaboration
Primary
Backup
White Sands Complex
USN, Wallops
Alerts
Raw Data
Instrument Uploads*
Commands*
Ops Data Products
Mission Operations Center
(MOC)
GBM
Level 0
Data
GLAST Burst
Monitor
(GBM) IOC
LAT ISOC
Level 0 and RT HK Data
Ops Data Products
Alerts
Refined
Alerts
Level 1 and Level 2 Data
Analysis Tools
Raw Data
Commands
Instrument
Uploads
GRB
Coordinates
Network
(GCN)
Refined
Alerts
Schedules and
Commanding
Level 1 and Level 2 Data
Analysis Tools
Schedules
Commands
Instrument Uploads
GLAST Science
Support Center
(GSSC)
* test, early orbit, and backup only
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GLAST LAT Project
ISOC CDR, 4 August 2004
Objectives



The LAT ISOC consists of several functional elements within
WBS 4.1.B, and science data products and science analysis
software produced under WBS 4.1.D (the SAS) all organized to
safely operate the instrument and produce the LAT’s science
data products.
Functions:
– Maintain and modify FSW and testbed
– Command generation, health and safety monitoring
– Performance verification and optimization
– Process and archive Level 1 and Level 2 data
– Develop and optimize the software pipeline that produces
the higher level products
These functions are organized as teams that share personnel
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GLAST LAT Project
ISOC CDR, 4 August 2004
Commanding, Health and Safety

The Commanding, Health and Safety (CHS) team is responsible
for:
– generation and validation of commands and command
sequences,
– passing commands on to the GSSC,
– verifying these commands were executed,
– receiving Level 0 data from the MOC,
– logging and archiving of all commands and Level 0 data,
– monitoring that data to ascertain and track the health and
safety of the instrument,
– continuous knowledge of the configuration of the LAT.
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GLAST LAT Project
ISOC CDR, 4 August 2004
Flight Software

The Flight Software (FSW) team is responsible for:
– Updating and validation of all flight software files,
– Debug or problem fixes to the FSW,
– Implementation, and validation on the instrument test bed
of authorized upgrades to FSW,
– Continuing maintenance of the instrument test bed to
ensure it is available to validate code and command
sequences as well as to investigate any anomalies seen on
orbit
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GLAST LAT Project
ISOC CDR, 4 August 2004
Performance Verification and Optimization

The Performance Validation and Optimization team (PVO) is
responsible for:
– instrument calibration from low level through IRFs,
– continuous monitoring of the LAT science performance,
identification of instrument performance trends and
resolution of anomalies,
– generation and initial validation of algorithms that improve
on-orbit performance of the LAT,
– management of test and calibration data collected prelaunch.
– Configuration and maintenance of the LAT reference
geometry and the LAT Monte Carlo Model.
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GLAST LAT Project
ISOC CDR, 4 August 2004
Science Products

The Science Products Team is responsible for
– Generation, archiving and distribution of the Level 1 data,
– Generation, archiving and distribution of specific Level 2
data needed for reference,
– Transient source detection,
– Configuration control over all pipeline code and generated
data sets.
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GLAST LAT Project
ISOC CDR, 4 August 2004
Science Analysis Software

The Science Analysis Software Team is responsible for
– Development and maintenance of the pipeline machinery
– Development and maintenance of the simulation,
reconstruction and event classification software
– Development and maintenance of the calibration
algorithms, including low level and Instrument Response
Functions
– Development and maintenance of the quicklook transient
analyses
– Development and maintenance of the high-level diagnostics
derived from reconstruction and classification
– Development and maintenance of the high-level analysis
tools
– “Help desk” support of ISOC staff
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GLAST LAT Project
ISOC CDR, 4 August 2004
ISOC Organization
ISOC Manager
Databases
4.1.B.10
Command, H&S
4.1.B.11
FSW
Documentation
4.1.B.12
Performance V&O
4.1.B.13
Science Products
4.1.B.14
Science Analysis
Software
Commanding
Thermal Control
Calibration
Level 1
CRs, gammas,
diagnostics
Health & Safety
Trigger
Performance
Trending
Level 2
Transients, GRBs
Calibration
Configuration
Filter
Standard Source
Monitoring
Pipeline Server
Reconstruction &
Event Classif.
Testbed
IRF Generation
LAT-PR-04500
Simulation
Transient Source
Analysis
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GLAST LAT Project
ISOC CDR, 4 August 2004
ISOC Organization Changes Since PDR




LOF, SOG, SAS structure refined
– Eliminates barriers between functions, personnel will be
shared amongst the functions
– Reduces segregation between scientists and engineers
implied by LOF/SOG structure.
All requirements are written for the ISOC, not pushed down to
the functional units.
Craig has been holding ISOC manager position, Cameron will
take over on Aug 16th. Lung was holding deputy position;
Martin now holds that position, assisted by Lung.
Overall LAT organization change now has ISOC reporting to
Drell as deputy project manager.
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GLAST LAT Project
ISOC CDR, 4 August 2004
LAT ISOC Major Changes Since 1st Peer Review

New architecture (e.g. use of ITOS)
 Revised requirements (significant help from GSFC)
 Rewritten operations plan reflects new requirements
and organization.
 Staffing and cost plan in place
 Staff additions (Craig, Culp, Martin, Steele, Lemon)
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GLAST LAT Project
ISOC CDR, 4 August 2004
RFAs (1/2)
No.
RFA Summary
Requestor
Actionee
Status
1
Need ISOC Management Plan & Approach
R. Schweiss
W. Craig
Closed 8/02
2
Need overall functional block diagram illustrating the functional
capabilities and data flow during various phases
R. Schweiss
L. Bator
Closed 7/15
3
Risk Analysis
R. Schweiss
W. Craig
Closed 6/9
4
Reschedule ISOC CDR
M. Rackley/
C. Young
D. Lung
Closed 6/9
5
Level III requirements for the LOF and SOG are not complete
M. Rackley
L. Bator
Closed 7/19
6
Staffing plan and profile
M. Rackley/
C. Young
W. Craig/
D. Lung
Closed 7/26
7
Define the ISOC reports for internal use and external use
M. Rackley
L. Bator
Closed 7/28
8
The ISOC does not yet know what system it is using to process
Observatory HSK data or perform the commanding
M. Rackley
L. Bator
Closed 6/24
9
Describe lesson learned & approach
M. Rackley
W. Craig
Closed 6/9
10
ISOC verification does not involve early opportunities to
validate/test using LAT instrument
M. Rackley/
N. Johnson
L. Bator
Closed 8/2
LAT-PR-04500
Section 1.0
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GLAST LAT Project
ISOC CDR, 4 August 2004
RFAs (2/2)
No.
RFA Summary
Requestor
Actionee
Status
11
Verify LAT modes
M. Davis
L. Bator
W. Craig
J. Martin
Submitted
12
Understand the number of writes to EEPROM
C. Young
L. Bator
Closed 8/02
13
ISOC detailed development schedule
K. Lehtonen
W. Craig
S. Culp
Closed 8/02
14
Enter a more formal agreement with SLAC management on
required data storage and processing requirements
N. Johnson
W. Craig
Closed 7/15
15
ISOC organization structure & communications
N. Johnson
J. Martin
Closed 7/19
16
Define mechanism for ISOC requirements being placed on I&T
and SAS
N. Johnson
J. Martin
Closed 7/19
17
Define LOF/SOG tools
R. Corbet
L. Bator
S. Culp
Closed 8/03
18
Specify plans and requirements for automation of Ops software
R. Corbet/
M. Rackley
L. Bator
S. Culp
Closed 8/03
19
Specify plans and requirements for Ops SW to be of sufficient
robustness
R. Corbet
S. Culp
Closed 8/03
20
Specify what other ground system elements will be involved in
LAT operations
R. Corbet
W. Craig
L. Bator
LAT-PR-04500
Closed 8/02
Section 1.0
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GLAST LAT Project
ISOC CDR, 4 August 2004
Summary




Major changes since March peer review
Architecture in place
– Based largely on existing tools
– Tools mapped directly to requirements
Planning ISOC verification with Test Bed and 3 demos prior to
first Ground Readiness Test
Ready to build, first software release is in April 2005.
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Section 1.0
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