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GLAST LAT Project IDT Face-to-Face Agenda
S. Williams 1
Face to Face MeetingFace to Face Meeting
Session Topic: LAT Operating Modes Date: March 19 Time: 13:30 Convener: Scott Williams Objectives:
– Collect, sort out, and distribute information as needed– Work with those who have worked on the issues and review
from a system point of view– Identify issues and propose plan for resolution
GLAST LAT Project IDT Face-to-Face Agenda
S. Williams 2
Mission Operations ArchitectureMission Operations Architecture
GRBCoordinates
Network
Mission Ops Center
Observatory safetySpacecraft healthCommandingMission schedulingInstrument data handling
LAT Instrument Operations Center
LAT data handlingLAT performanceStandard product processing
Science Support Center
Science schedulingArchivingGuest Observer Support Standard product processing
GBM Instrument Operations Center
GBM data handlingGBM performanceStandard product processing
Burst and transient Alerts
AlertsLarge loadsTarget of OpportunityCommands
Routine Dataand commands
Spacecraft, IOC, and GBM data
Standard productsSchedule requests
Standard productsSchedule requests
LAT Data Command Loads Status
GBM DataStatusCommand Loads
Five contactsper day
Alerts
GLASTTDRSS
Malindi
Level 0 data for archiving
Schedules
WhiteSands
GLAST LAT Project IDT Face-to-Face Agenda
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GLAST Mission PhasesGLAST Mission Phases
• Launch Data – March 2006• Phase 0 - Launch & early orbit: up to 60 days
– S/C configuration and checkout: 10 days• LAT responsible for LAT thermal control using survival power bus
– LAT turn-on, configuration, and checkout: 20 days• Subsystem checkout• Initial on-orbit calibration and alignment
– LAT commissioning – 30 days• Science observation modes exercised and instrument response
functions established
• Phase 1 – Verification and Sky Survey: 12 months– LAT science verification– up to 20% of observing time for LAT calibration and test
• Phase 2 – Science Observations: minimum 4 years– Peer review driven investigations– 5% observing time for LAT calibrations and maintenance
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Mission OperationsMission Operations
• Routine operations– All sky survey for first year– Pointed observations in subsequent years– Minimal pointing constraints– Health and safety check of observatory
• Real-time operations– Gamma ray Burst Alerts
• Current observation autonomously interrupted for selected burst
• Bursts observed for 5 hours then returned to interrupted observation
– Transient detection alert– Anomaly alert– Target of Opportunity
• Downlink volume– ~28 Gb per day
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LAT Operations ConceptLAT Operations Concept
• LAT science operations
– Driven by goals of the mission, which require the LAT to detect celestial gamma rays, discriminate charged particles, and maintain high observing efficiency
• Nominal orientation is zenith pointed– Avoid obstructing the FOV of the LAT, and avoid the albedo
gamma rays from cosmic-ray interactions in the upper atmosphere– ‘Rocking’ about this orientation will be standard, to make the
coverage of the sky more uniform– Inertially pointed observations and hybrid ‘pointed scan’ mode will
also be employed
• Event data, after onboard background rejection, is accumulated in SSR
– Rejection filters from few kHz rate to ~30 Hz
– Retain candidate gamma rays and cosmic rays useful for calib.
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LAT Operations Concept (2)LAT Operations Concept (2)
• Space-to-ground communications
– Five daily downlinks scheduled for Malindi at 15 Mbps
• Average data rate will be ~300 kbps for the LAT
– Alerts will be transmitted via TDRSS DAS through the WSC ground stations to MOC
• Data rate is low (~1 kbps) but message length is short
• Low latency is vital: initial information about science transients (GRBs, AGN flares, etc.) detected by GBM or LAT, or onboard anomalies generated by the S/C or instruments
• Ground-to-space communications
– Command uploads (via S-band, 2kbps) - ~weekly
– Calibration table uploads (S-band, 2kbps) - infrequently
– Flight software uploads (via TDRSS MAS, 4kbps) - very infrequently
– ToO commanding (TDRSS MAS, 4kbps) - infrequent
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GLAST Science Data FlowGLAST Science Data Flow
5 contacts/day6-7 minutes each15 Mbps
• Send real time housekeeping to IOCs
• Buffer playback data and send as bandwidth allows
• Oldest data typically <1 day old when received at MOC
• Ground station saves data for at least seven days; MOC can request retransmission within that time.
Mission Operations Center
LAT Instrument Operations Center
Real time Housekeeping Recorded spacecraftRecorded GBM dataRecorded LAT data
Level Zero Processing
GBM Instrument Operations Center
Science Support Center
Higher level ProcessingArchivingData Distribution
Real time GBM H&SRecorded GBM DataReal time or playback S/C (as requested)
Spacecraft Level 0 GBM level 0GBM Level 1GBM standard products
LAT level 0LAT Level 1LAT standard products
Real time LAT H&SRecorded LAT Data Real time or playback Spacecraft (as requested)
S/C Health & Safety
GBM Ops & monitoring
GBM processing
LAT performance monitoring
LAT level 0 verification
LAT level 1 and higherLevel processing
Malindi
28 Gbits/day 1 GBM 1 Spacecraft 26 LAT
GLAST LAT Project IDT Face-to-Face Agenda
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Schedule and Command Data FlowsSchedule and Command Data Flows
5 contacts/day 2 kbps
Mission Operations Center
LAT Instrument Operations Center
GBM Instrument Operations Center
Science Support Center
Command LoadsGBM S/W Loads
GBM Schedule Request
LAT Schedule Request
Command LoadsLAT S/W Loads
Large LoadsTarget of Opportunity Commands
Commands
Target of Opportunity RequestInstrument Activity Schedule
Instrument/Science SchedulingTarget of Opportunity Selection
GBM SchedulingGBM instrument S/WGBM Command Generation
LAT SchedulingLAT instrument S/WLAT Command Generation
Spacecraft Command GenerationLoad Integration and FormattingGround Station SchedulingPlanning Data
SchedulesAcquisition data
SchedulesAcquisition data
As-flown timeline
Malindi
WhiteSands
As-flown timeline
As-flown timeline
0.4 to 4 kbps
S-band, 2kbpsCommand uploads - ~weekly
Calibration table uploads - infrequently
TDRSS MAS, 0.5 to 4kbpsToO commanding - infrequent
Flight software uploads - very infrequently
GLAST
TDRSS
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GLAST Alert Data FlowsGLAST Alert Data Flows
• When LAT, GBM, or S/C decide to issue an alert (ideally science related), data will be downlinked via TDRSS DAS to White Sands then on to the MOC
• Alert processor must be located in facility with high availability - MOC
• Latency of 14 seconds includes 7-10 seconds to lock onto DAS
• GBM generates coordinates onboard; Algorithm in alert processor will provide more accurate estimate MOC will distribute GRB-related information to GCN
• MOC will also pass LAT-related data to the IOC
Mission Operations Center
Alert Processor
Latency from spacecraft toMOC less than 14 seconds
Sorter LAT AlertsReformat
GBM AlertsProcess
SafetyAlerts
GCN
LATIOC
GBMIOC
LAT Data
GBM Data
Alerts
Attitude ManeuverNotification
1 kbps for up to5-10 minutes
WhiteSands
TDRSS
GLAST
GLAST LAT Project IDT Face-to-Face Agenda
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GLAST Observatory Operational ModesGLAST Observatory Operational Modes
• Launch• Early Orbit• Observatory
Verification• Safe
– Software– Hardware– Survival– Recovery
• Standby/Engineering• Normal Operations• Re-entry
Launch Mode
Observatory Verification
Mode
EarlyOrbitMode
Normal Operations
Mode
Standby/ Engineering
Mode
Re-entryMode Safe Mode
Survival Mode
Hardware Mode
Software Mode
Safe Mode
Recovery
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LAT Operating ModesLAT Operating Modes
• Science Observing Modes - Standard, GRB, and Solar Flare (TBR) distinguished by trigger criteria and post-trigger filtering.
• Standby Modes– Ready - Subsystems configured and ready to start nominal observing.– Engineering - Used for flight software update, parameter changes, subsystem
configuration changes, and engineering tests.– Calibration - Raw L1T data collection and other subsystem calibrations which
impact science observing efficiency or LAT dead time.– SAA Mode - Safing of ACD for South Atlantic Anomaly (SAA) passage.
• LAT Power Up and Safe Modes– Detectors On - All detector subsystems powered on and housekeeping active.– T&DF On - LAT T&DF powered on, configured, and housekeeping active.– LAT Hardware Safe Mode - SIU powered, performing thermal monitoring and
control(TBR), and providing housekeeping. All S/C interfaces active.– LAT Survival Mode - LAT powered off and performing thermal control with
survival heaters. Temperatures are stable, no duration in mode time limit.– Pre-deploy Mode - Launch and early orbit mode. LAT powered off, radiator
heaters active. LAT thermal environment is not stable and transition to Survival Mode must be made within TBD time constraint.
– LAT Off - Pre-launch and re-entry mode, LAT and survival bus power off.
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LAT Operating Mode TransitionsLAT Operating Mode Transitions
• Power up sequence is a progression through the defined LAT modes.– LAT Off– LAT Pre-Deploy– LAT Survival– LAT Hardware Safe– T&DF On– Detectors On– Ready– Observing Mode
S/C Survival Mode S/C Early Orbit Mode
S/C Hardware Safe Mode S/C Observatory Verification Mode
S/C Science Operations Mode S/C Observatory Verification Mode
S/C Standby / Engineering Mode S/C Observatory Verification Mode
Power on ACD CAL and TKR
T&DF On All DAQ electronics powered on and configured
LAT Hardware Safe LAT (SIU) power switched on by S/C LAT thermal control by LAT, survival heaters on Housekeeping and all S/C interfaces active
Dectectors On All systems powered on and subsystem housekeeping active
Ready Mode LAT configured and ready for observing
Engineering Modes S/W load, parameter changes
subsystem configuration changes.
Calibration Modes
Raw L1T data collection, Subsystem calibration modes which impact science
Observing Mode LAT Science Observing
LAT Survival LAT powered off, survival heaters on LAT perform LAT thermal control
SAA Mode ACD HV safing
Power on SIU
Power on and config T&DF
Begin Science Ops
S/C Software Safe Mode S/C Observatory Verification Mode
Configure Subsystems
{
LAT Standby Modes
S/C Launch Mode
S/C Reentry Mode
LAT Pre-deploy LAT powered off, survival heaters on LAT perform LAT thermal control
Power On Heaters
S/C PreLaunch Mode LAT Off
LAT powered off, No thermal control
Power On Radiator Htrs
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Correlation of LAT and S/C ModesCorrelation of LAT and S/C Modes
LAT Safe Modes entered based on S/C action– S/C Software Safe Mode / LAT Ready
• inhibit triggering and data transfer to SRR– S/C Hardware Safe Mode / LAT Hardware Safe
• power down detectors and T&DF, but keep SIU operational to provide housekeeping
– S/C Survival / LAT Survival• power down LAT and rely on survival heaters
LAT Modes
S/C ModesPower
OffPre-
Deploy SurvivalH/W Safe
T&DF On
Detectors On
SAA Mode Calib. Eng. Ready
Science Obs.
Modes
Launch XEarly Orbit X XObservatory Verification X X X X X X X X XSurvival Mode XHardware Safe Mode XSoftware Safe Mode X XSafe Mode Recovery X X X X X X X XStandby/Engineering X X X XScience Operations XRe-entry X
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Background MaterialBackground Material
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• Launch Date: March 2006
• Mission Life: 5 year required with 10 year goal
• Orbit: 450 to 550 km circular orbit, 28.5° inclination.
• Spacecraft: RSDO spacecraft, to be selected ~summer 2002.
• Mission Operations Center: TBD, to be selected ~spring 2003.
• Ground Link: Ground Station (Malindi) – Five contacts per day to dump the bulk science data. Data volume is 28 Gbits per day. Downlink rate is 15 Mbps (TBR) over an X-band link. 32 kbps S-band downlink for real time housekeeping telemetry. Command uplink is 2 kbps
• Space Link: Space Network – Demand Access System (DAS, 1 kbps) used for gamma-ray burst alerts, health and safety alerts, and other science and housekeeping functions. Single Access Service (SAS, 4 kbps) used for large command uploads and early orbital operations. Multiple Access Service (MAS, 500 bps) used for TOO commanding.
• Operations Constraints: Earth limb avoidance, radiator, and solar panel pointing constraints. Spacecraft may autonomously adjust its operation (including its pointing) in response to a gamma-ray burst.
Mission Operations OverviewMission Operations Overview
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DefinitionsDefinitions
• Alert– Packetized data transmitted by the spacecraft in response to a transient event.
Alerts can be generated by instrument or spacecraft subsystems in response to the detection of anomalies or by the science instruments in response to transient scientific phenomena.
• Phase– Time period in mission characterized by unique operating modes or
constraints. • Mode
– A specific configuration and set of operations or behavior that accomplish a specific purpose and impact the LAT to S/C interface.
• Observing Efficiency– Fraction of time available that is spent acquiring data. On the GLAST mission
the time available is the time on orbit less time spent in the South Atlantic Anomaly (SAA).
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DefinitionsDefinitions
• Level 0 Processing - Space-to-ground artifact removal– Processing of raw instrument data. Level 0 data processing consists of time-
ordering packets, removing corrupted, incomplete, or duplicate packets, annotating quality, and can include separating housekeeping, calibration, science, and engineering data streams.
• Level 1 Processing– Processing level 0 data into level 1 data consists of creating a database of
reconstructed gamma-ray photons and cosmic rays which includes energy, direction of arrival, arrival time, quality parameters, and associated pointing and livetime history.
• Higher Level Science Processing– Processing of level 1 data into science products. Consists of calculating
exposures, detecting sources, measuring their spectra, determining their time histories, and locating potential counterparts in other astronomical catalogs .
GLAST LAT Project IDT Face-to-Face Agenda
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ASINet Central NodeFucino, Italy
Prime - 2 Mbps Intelsat
Backup - 500 kbps
Malindi gets ~35 Gbits per day from GLAST and 26 GbitsFrom Swift, and AGILE
Equivalent to ~400 kbpscontinuous
JSCHouston
MOC(TBD)
LAT IOCStanford
32 Mbps
NISN orASINet
NISN or Internet 2 via JPL
NISN should support whatever rates we deem necessary for the desired latency Another option is Internet 2
Realtime S-Band Data and SSR Data
Realtime S/C and LAT HSK DataFollowed by processed Level 0 Data
Malindi
NISN or Internet 2 via ARC
LAT Data PathLAT Data Path
Realtime data: 32 kbps S-bandSSR dump: 15 Mbps X-band
GLAST LAT Project IDT Face-to-Face Agenda
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LAT Operations Facility FunctionsLAT Operations Facility Functions
Mission Operations
Center (MOC)
LAT Instrument Operations & Science Data Processing
GBM Instrument Operations
Center
S/C LAT, and GBM Data, Commands
Level 1 Data, High Level Products, GBM IOC Data Products, GBM
Schedules, Science Plan
LAT Operations Facility WBS 4.1.B
S. Williams, SU-HEPL LAT Data VerificationLAT Health & SafetyMonitoring LAT Commanding Test & Calibration Data Acquisition Validating & Maintaining Flight Software Alert Processing
Data Processing Facility WBS 4.1.D
R. Dubois, SU-SLAC Science Data ProcessingOptimizing Analysis & Processing Algorithms LAT Calibration LAT Performance Assessment Data DistributionAnalysis SoftwareMirror Sites
Science Plan, LAT Schedules
Level 0 Science & Hsk Data
Performance & Cal Data
Level 0 Data, LAT Procs & Uploads Science
Support Center (SSC)Science Plan,
Schedules, Level 0 Data
Space and Ground Segments
Level 1 Data, High Level
Products, LAT IOC Data Products
The LOF will consist of about 1/2 the resource of the FUSE Control Center at Johns Hopkins University (as shown here).
Level 0 Data, GBM Procs & Uploads
GLAST LAT Project IDT Face-to-Face Agenda
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GLAST Mission Operations CenterGLAST Mission Operations Center
SPACENETWORK
GRB COORDINATES
NETWORKSSC
LAT IOCGROUNDSTATION
NETWORK
Mission Operations
Center
Real-time telemetry
Selected Playback Tlm
Commands, Loads
As flown timelines
LAT Alerts
GBM IOC
Real-time telemetry
Selected Playback Tlm
Commands, Loads
As flown timelines
GBM Alerts
Alerts, Telemetry Commands, TOO, Loads Schedules
Status
Orbit Data
As flown timelines
Real-time Telemetry
GBM, Playback,S/C tlm
Commands, Loads
Schedules
Status
Acquisition Data
Burst/Transient
Alerts
Schedules
S/C data for archiving
TOO
• Mission Scheduling• Commanding• Observatory safety• Spacecraft health• Orbit Prediction• Alert message routing• GBM Data Handling• Data Distribution• Instrument Health
GBM Data Sets
LAT Data Sets
GLAST LAT Project IDT Face-to-Face Agenda
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ReferencesReferences
• GSFC 433-SRD-0001, GLAST Science Requirements Document, P. Michelson and N. Gehrels, eds., September 23, 2000.
• GSFC 433-OPS-0001, GLAST Operations Concept Document, Baseline, March 8, 2002.• GSFC 433-PLAN-0009, GLAST Project Data Management Plan, DRAFT, December
2001.• GSFC 433-SPEC-0001, GLAST Project Mission System Specification, April 24, 2001.• GSFC 433-IRD-0001, GLAST Science Instrument - Spacecraft Interface Requirements
Document, January 23, 2001.• LAT-TD-00428-03, LAT Instrument Operations Center Preliminary Design Report,
January 31, 2002.• LAT-TD-00447, GLAST LAT Calibration Plan, December 5, 2001.• LAT-TD-00446, GLAST LAT Calibration Requirements, December 5, 2001.• LAT-TD-00499, LAT Operating Modes, 30 May 2001.• LAT-TD-00501, LAT Mission Phases, 12 December 2001.• LAT-SP-00015, LAT Instrument Operations Center - Level II Specification, Sept. 1,
2000.• LAT-SS-00021-07, LAT Operations Facility Subsystem Specification-Level III
Specification, January 7, 2002.
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