GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
ISOC Peer Review - March 2, 2004
GLAST Large Area Telescope
ISOC Peer Review
3.0 LOF Operations Concept
Lori Bator
ISOC Chief Engineer
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
1
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Topics
3.1 Instrument Operation
3.2 Command and Telemetry Operations
– Housekeeping Telemetry
– Thermal Control System
– Commanding
– Flight Software Maintenance
3.3 Operations Products
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
2
GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
ISOC Peer Review - March 2, 2004
GLAST Large Area Telescope
ISOC Peer Review
3.1 Instrument Operations
Lori Bator
ISOC Chief Engineer
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
3
GLAST LAT Project
ISOC Peer Review - March 2, 2004
LAT Operation Phases
•
•
Ref: LAT Mission Phases (LAT-TD-00501)
Launch and Early Orbit (Phase 0)
– Instrument test teams will augment the Flight Operations Team
(FOT)
• Staffed around the clock for the initial checkout, transition to
prime shift only operation by end of phase
– Instrument state turn-on occurs after solar array deployment
– Instrument activation and functional checkout – 20 days
• Test various trigger modes of the instruments
• Perform initial instrument alignments
• Verify all observatory observation modes
• Characterize data volumes
– Science commissioning period – 30 days
• Characterize initial science performance using pointed
observation mode and known targets
• Verify sky survey (scanning) mode and a multiple target mode
involving scan-pointing
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
4
GLAST LAT Project
ISOC Peer Review - March 2, 2004
LAT Operation Phases, cont’d
• Verification and Sky Survey (Phase 1)
– One year
– Fully characterize, validate, and verify science instruments
– Primarily operate in sky survey mode
– Science calibration
• Science Observation (Phases 2-5)
– Guest observation period for remaining mission life
• End of life
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
5
GLAST LAT Project
ISOC Peer Review - March 2, 2004
LAT Modes
Instrument
SC Mode
LAT Modes
TCS Modes
Pre-Launch
Off
Off
Launch/Ascent
Off
Launch
Mission Modes
Early Orbit
Standby/Engrg
Deployment/Activation
Engineering
Pre-Deploy
LAT Survival
TCS Survival
Engineering
Transition
Calibration
Nominal
SAA
Sky Survey
Pointed and
Repointed
Sky Survey
Sky Survey
Nominal
Pointed and
Repointed
Nominal
Hardware Safe
TCS Safe
Power Safe
Survival
Survival
Re-Entry
Off
Off
Pointed and Repointed
Observatory Safemode
Safemode
Re-Entry
Document: LAT-PR-03213-01
Independent Safemode
Section 3 LOF Operations Concept
6
GLAST LAT Project
ISOC Peer Review - March 2, 2004
LAT Modes, cont’d
Valid science
data
Observing
Modes
Observing Modes
A,C
Sky
Survey
A,C
C
A
,C
Sky Survey
Pointed
Pointedand
&
Repoint
Repoint
C
Science data
may not be valid
A,C
A,C
C
C
SAA
SAA
Engineering
Eng
C
C
Standby
Modes
Standby Modes
Calibration
Cal
C
Safing
Safing
No science
data
C
C
Hardware
Hardware
Safe
A = Autonomous
C = Commanded
Survival
Survival
C
C
Launch &
Early Orbit
Launch & Early
Document: LAT-PR-03213-01
Launch
Launch
Section 3 LOF Operations Concept
7
GLAST LAT Project
ISOC Peer Review - March 2, 2004
LAT Modes, cont’d
• Launch Mode and Early Orbit Modes
• Standby/Engineering Mode
– Engineering Sub-Mode
• Used for troubleshooting and diagnostics, initiating the
use of new software loads, and raw data downlinks
– Calibration Sub-Mode
• LAT performs Charge Injection (CI) for on-board
calibration and support raw data collection
– South Atlantic Anomaly (SAA) Safe Mode
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
8
GLAST LAT Project
ISOC Peer Review - March 2, 2004
LAT Modes, cont’d
• Observation Modes
– Sky Survey Sub-Mode
• Zenith Pointing (Pointed Observation)
• Rocking
– Pointed Observation Sub-Mode
• Z-axis of the observatory is pointed to a commanded
celestial target
– Repoint Sub-Mode
• Target of Opportunity (TOO)
• Repointed Observation
• Autonomous repoint for a gamma-ray burst
• Safe Modes
– Hardware
– Survival (LAT powered off)
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
9
GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
ISOC Peer Review - March 2, 2004
GLAST Large Area Telescope
ISOC Peer Review
3.2 Command and Telemetry
Operations
Lori Bator
ISOC Chief Engineer
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
10
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Housekeeping Telemetry
• Housekeeping data consists of
– Environmental monitors
• Temperature, voltage, current
– Low rate science
• Counters, deadtime, error messages, status, event
statistics
– Communications Statistics
• Command response, traffic counters
– CPU Metrics
• SIU and EPU monitoring
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
11
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Housekeeping Telemetry, cont’d
• HK data is collected according to a schedule loaded in flight
software
– Collection of telemetry depends on configuration tables and
FSW operational modes
• Boot mode provides small amount of status and error
reporting during SIU boot
• Operational mode provides full set of HK data collecting
at nominal rates
• Science acquisition mode utilizes the operational
parameters plus increased low-rate science counter
collection rates
• Safe mode configuration collects only critical data
necessary for health assessment and failure diagnostics
– Schedule identifies the order and type of packets
• Autonomous and commanded collection schedules
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
12
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Housekeeping Telemetry, cont’d
• HK data is monitored according to limit tables
• Configuration files can be uploaded to modify the collection
table, schedule table, and limit table
• Commands can be sent to enable or disable threshold
checking, alarming, and alarm response actions
• Commands are sent to request specific telemetry packets
(demand telemetry)
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
13
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Thermal Control System
• Thermal Control System (TCS) is implemented by LAT flight
software to fine-tune the thermal profile of the LAT with the
goal of minimizing distortions of the mechanical structure
– Design of TCS is described in LAT-SS-02896
• Two temperature sensors and one heater controller on each of
12 heat pipes on each of two radiators
– TCS turns heaters on or off for a fixed period of time
– Watchdog timer activates if TCS does not get any input
after one minute
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
14
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Telemetry Control System (TCS)
• Modified through uploads to tables
– Mapping Table identifies sensors electronically
– Parameter Table identifies which sensors are used by TCS
and the limits for each
• TCS monitoring data included in housekeeping telemetry
– Active sensor and heater status
– TCS state information
– Temperature values
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
15
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Commanding Structure
• File uploads
– Primary method of getting instructions into the LAT
• Configuration changes
• Calibrations
– Generate file uploads using data from SOG
– Files are validated on test bed
– Human-readable information sent with data file when
transmitted to the GSSC
• File name
• Description of what it does
• Size of file
• Time conditions
• Criticality
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
16
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Commanding Structure, cont’d
• Single command or group of single commands
– Used for specific tasks
• File upload (start, cancel, delete, copy, commit)
• Memory dump
• Boot commands
• Diagnostic and test commands
– Often involve parameters to identify memory location, units,
names of files, etc.
– Commands are identified by file mnemonics in a procedure
provided to GSSC
• Procedure identifies activity, command parameters, time
conditions, and criticality
• Procedure is validated on test bed
• Commands generated by FOT using LAT database
information
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
17
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Command Planning
• Instrument plan and the associated operations procedures are
provided to GSSC
– Format of this communication is being developed and will
be documented in the Operations Data Products ICD
• GSSC generates the integrated observatory schedule and must
have knowledge of whether the instrument activity affects
pointed observations or impacts the TDRS schedule
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
18
GLAST LAT Project
ISOC Peer Review - March 2, 2004
SOG
LOF generates
operations
procedures and
data files
SOG provides
input data to LOF
LOF validates
operations
procedures and
data files
GSSC
LOF reviews
operations
procedures and
data files with
SOG
GSSC creates
observatory
schedule
GSSC sends
schedule to MOC
MOC
ISOC
SOG determines
instrument plan
and schedule
LOF
Command Scheduling Concept
MOC schedules
TDRS contacts
and works
scheduling issues
with GSSC
MOC uploads
commands to
spacecraft
Document: LAT-PR-03213-01
LOF sends
operations
procedures and
data files to GSSC
Section 3 LOF Operations Concept
19
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Command Timeline Concept
Deadline for LOF to
send commands that
DO NOT affect or are
NOT impacted by
attitude
Deadline for LOF to
send commands that
affect or are impacted
by attitude
GSSC generates
observatory plan
GSSC amends
observatory plan
MOC prepares
command load
TDRSS scheduling
Schedule is
uploaded to S/C
MOC schedules
TDRSS
Document: LAT-PR-03213-01
MOC receives
observatory plan
Section 3 LOF Operations Concept
20
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Database
• LOF is responsible for the command and telemetry database
during operations
• Database is initially being developed by the Flight Software
group for use in FSW development
– Developed an XML-based representation of the command
and telemetry database
– Includes an editor tool to manipulate the XML files
– Includes extraction tools to produce
• ITOS database interchange records (format documented
in Database Format Control Document (DFCD))
• Database documentation
• Source code for inclusion in FSW applications
• Command and telemetry database will be further developed for
I&T and ISOC use by I&T, ISOC, and system engineering
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
21
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Database, cont’d
• LAT delivers database to Spectrum Astro in format identified
by DFCD prior to spacecraft integration and provides updates
prior to launch
• ISOC delivers post-launch updates to MOC in format identified
by DFCD and Operation Data Products ICD
• Database will be under configuration control
– On-orbit changes must be approved by Operations CCB
• Initial validation occurs during I&T
– After I&T and during on-orbit operations, changes will be
validated on the test bed
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
22
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Flight Software
• LOF is responsible for maintaining the Instrument Flight
Software on-orbit
– Status of on-board software
– Verification and validation of uploads
– Development of software patches
• Section 4.2 will describe the tools that will be used by LOF
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
23
GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
ISOC Peer Review - March 2, 2004
GLAST Large Area Telescope
ISOC Peer Review
3.3 Operations Products
Lori Bator
ISOC Chief Engineer
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
24
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Operations Products
• Operations Products from MOC
• Operations Products from ISOC
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
25
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Operations Products from MOC
• Level 0 Data
– After each pass, MOC processes virtual channel telemetry
frames received via White Sands or ground network
stations to create individual Level 0 packet files
– MOC notifies ISOC of availability of Level 0 data within four
hours
• Real-time (RT) Housekeeping Data
– Provided by MOC through a separate Internet socket
– Need for RT data at ISOC is under review
• Remote access to RT and archived data at MOC
– View RT telemetry during a contact using ITOS Java display
pages over the Internet
– Use of Data Trending and Analysis System to view plots
and tables of HK and trend data
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
26
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Operations Products from MOC, cont’d
• Integrated Observatory Timeline
– Text listing of commands contained in the ATS loads along
with predicted orbital events
• As-Flown Timeline
– Actual observation times and attitude data from the
spacecraft Solid State Recorder (SSR)
• Observatory Telemetry and Command Database Updates
– Updates to the project database, which includes spacecraft
and GBM parameters
– Database changes are approved by Operations CCB
– Updates are made available on MOC file server in format
documented in DFCD
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
27
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Operations Products from MOC, cont’d
• LAT Memory Dumps
– LOF is notified when and where to retrieve memory dump
data from MOC web server
• MOC Command Logs
– ASCII text files of all commands sent to the spacecraft
• Flight Dynamics Orbital Products
– TDRSS and GLAST ephemerides
• Anomaly Reports
– MOC notifies the LOF of any spacecraft or instrument
anomaly
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Operations Products from ISOC
• Data Retransmission Requests
– Text notification to MOC to request a retransmission of
Level 0 data
• LAT Telemetry and Command Database Updates
– Approved by Operations CCB
– Validated on test bed
– Format as defined in DFCD
• LAT Anomaly Incident Reports
– LOF notifies MOC of instrument anomalies
– Text files of LAT anomalies made available to MOC
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
29
GLAST LAT Project
ISOC Peer Review - March 2, 2004
Operations Products from ISOC, cont’d
• LAT Operations Procedures
– Provided to GSSC during on-orbit operations and provided
to MOC during early-orbit testing and during contingencies
if necessary
– Used to identify instrument activities
• Involve instrument commands, but could also be used
to identify special monitoring situations
• Handle routine, one-time use, test, and contingency
situations
• Where possible, procedures derive from I&T tests
– Configuration controlled by LOF
– Validated on test bed, or during I&T when applicable
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Operations Products from ISOC, cont’d
– LAT Operations Procedures are in human readable format
as defined in GSFC Doc #492-MOC-004 GLAST Project
Procedure/PROC Style Guide
• Purpose and description of activity
• References
• Initial and final conditions
• Cautions and constraints
• Identification of child/parent procedures
• Step by step list of actions with command
–
–
–
–
Document: LAT-PR-03213-01
Individual command mnemonics with parameters
Names of command upload data files
Expected response for each step
Comments including relevant contingency procedures,
reference material, etc.
Section 3 LOF Operations Concept
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Conclusions
• Flight software definitions for command and telemetry are in
place
• Have concepts for managing and scheduling instrument
commanding
– LAT Operations Plan (LAT-SS-01378) in draft
– Operations Data Products ICD (492-MOC-0009) in draft
• ISOC will be hiring a software engineer to help develop the
database with I&T
• Interfaces have been identified in the Operations Data
Products ICD – continue to update the plan and work out the
details
Document: LAT-PR-03213-01
Section 3 LOF Operations Concept
32