face to face meeting

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


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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


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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


Real time Housekeeping Recorded spacecraftRecorded GBM dataRecorded LAT data

Level Zero Processing



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


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Schedule and Command Data FlowsSchedule and Command Data Flows

5 contacts/day 2 kbps





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


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


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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 .


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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


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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


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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


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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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