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Face 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

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Face to face meeting

Face 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


Mission operations architecture

Mission Operations Architecture

LAT Instrument Operations Center

LAT data handling

LAT performance

Standard product processing

Alerts

TDRSS

GLAST

Five contacts

per day

Routine Data

and commands

LAT Data

Command Loads

Status

Standard products

Schedule requests

Malindi

White

Sands

Science Support Center

Science scheduling

Archiving

Guest Observer Support

Standard product processing

Spacecraft, IOC, and GBM data

Mission Ops Center

Observatory safety

Spacecraft health

Commanding

Mission scheduling

Instrument data handling

Alerts

Large loads

Target of Opportunity

Commands

Schedules

Level 0 data

for archiving

Standard products

Schedule requests

GBM Instrument Operations Center

GBM data handling

GBM performance

Standard product processing

GRB

Coordinates

Network

Burst and

transient

Alerts

GBM Data

Status

Command Loads


Glast mission phases

GLAST 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


Mission operations

Mission 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


Lat operations concept

LAT 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.


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


Glast science data flow

GLAST Science Data Flow

28 Gbits/day

1 GBM

1 Spacecraft

26 LAT

GBM Ops & monitoring

Level Zero Processing

5 contacts/day

6-7 minutes each

15 Mbps

Real time GBM H&S

Recorded GBM Data

Real time or playback S/C

(as requested)

GBM processing

S/C Health & Safety

GBM Instrument Operations Center

Real time Housekeeping Recorded spacecraft

Recorded GBM data

Recorded LAT data

Malindi

Mission Operations Center

Real time LAT H&S

Recorded LAT Data

Real time or playback Spacecraft

(as requested)

Spacecraft Level 0

GBM level 0

GBM Level 1

GBM standard products

  • 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.

LAT performance

monitoring

Higher level Processing

Archiving

Data Distribution

LAT level 0

LAT Level 1

LAT standard products

LAT level 0 verification

Science Support Center

LAT level 1 and higher

Level processing

LAT Instrument Operations Center


Schedule and command data flows

Schedule and Command Data Flows

TDRSS

0.4 to 4 kbps

White

Sands

GLAST

Schedules

Acquisition data

Large Loads

Target of Opportunity Commands

GBM Scheduling

GBM instrument S/W

GBM Command Generation

Command Loads

GBM S/W Loads

Spacecraft Command Generation

Load Integration and Formatting

Ground Station Scheduling

Planning Data

5 contacts/day

2 kbps

As-flown timeline

Commands

GBM Instrument

Operations Center

Schedules

Acquisition data

Mission Operations Center

Target of Opportunity

Request

Instrument Activity

Schedule

Malindi

As-flown timeline

Command Loads

LAT S/W Loads

GBM Schedule Request

  • S-band, 2kbps

    • Command uploads - ~weekly

    • Calibration table uploads - infrequently

  • TDRSS MAS, 0.5 to 4kbps

    • ToO commanding - infrequent

    • Flight software uploads - very infrequently

As-flown timeline

LAT Scheduling

LAT instrument S/W

LAT Command Generation

Instrument/Science Scheduling

Target of Opportunity Selection

LAT Schedule Request

LAT Instrument

Operations Center

Science Support Center


Glast alert data flows

GLAST Alert Data Flows

TDRSS

  • 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

GLAST

1 kbps for up to

5-10 minutes

White

Sands

Latency from spacecraft to

MOC less than 14 seconds

Alerts

GCN

LAT Alerts

Reformat

Sorter

LAT

IOC

LAT Data

GBM Alerts

Process

Safety

Alerts

Alert Processor

GBM

IOC

GBM Data

Attitude

Maneuver

Notification

Mission Operations Center


Glast observatory operational modes

Safe Mode

Software

Mode

Safe

Mode

Recovery

Hardware

Mode

Survival

Mode

GLAST Observatory Operational Modes

  • Launch

  • Early Orbit

  • Observatory Verification

  • Safe

    • Software

    • Hardware

    • Survival

    • Recovery

  • Standby/Engineering

  • Normal Operations

  • Re-entry

Standby/

Engineering

Mode

Launch

Mode

Early

Orbit

Mode

Observatory

Verification

Mode

Normal

Operations

Mode

Re-entry

Mode


Lat operating modes

LAT 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.


Lat operating mode transitions

LAT 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


Correlation of lat and s c modes

Correlation 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


Background material

Background Material


Mission operations overview

Mission Operations Overview

  • 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.


Definitions

Definitions

  • 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).


Definitions1

Definitions

  • 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 .


Lat data path

LAT Data Path

Realtime data: 32 kbps S-band

SSR dump: 15 Mbps X-band

Prime - 2 MbpsIntelsat

ASINet

Central Node

Fucino, Italy

JSC

Houston

32 Mbps

Backup - 500 kbps

Malindi

Realtime S-Band Data and

SSR Data

Malindi gets ~35 Gbits per

day from GLAST and 26 Gbits

From Swift, and AGILE

Equivalent to ~400 kbps

continuous

NISN or

ASINet

NISN or Internet 2 via JPL

MOC

(TBD)

LAT IOC

Stanford

NISN or Internet 2 via ARC

NISN should support whatever rates we deem necessary for the desired latency Another option is Internet 2

Realtime S/C and LAT HSK Data

Followed by processed Level 0 Data


Lat operations facility functions

The LOF will consist of about 1/2 the resource of the FUSE Control Center at Johns Hopkins University (as shown here).

LAT Operations Facility Functions

LAT Instrument Operations & Science Data Processing

Data Processing Facility WBS 4.1.D

LAT Operations Facility WBS 4.1.B

Level 0 Science & Hsk Data

S. Williams, SU-HEPL

R. Dubois, SU-SLAC

  • LAT Data Verification

  • LAT Health & Safety

    Monitoring

  • LAT Commanding

  • Test & Calibration Data Acquisition

  • Validating & Maintaining Flight Software

  • Alert Processing

  • Science Data Processing

  • Optimizing Analysis & Processing Algorithms

  • LAT Calibration

  • LAT Performance Assessment

  • Data Distribution

  • Analysis Software

  • Mirror Sites

Performance & Cal Data

Science Plan, LAT Schedules

Level 0 Data, LAT Procs & Uploads

Science Support Center (SSC)

Level 1 Data, High Level Products, LAT IOC Data Products

Mission Operations Center (MOC)

Science Plan, Schedules, Level 0 Data

Level 1 Data, High Level Products, GBM IOC Data Products, GBM Schedules, Science Plan

S/C LAT, and GBM Data, Commands

GBM Instrument Operations Center

Space and Ground Segments

Level 0 Data, GBM Procs & Uploads


Glast mission operations center

GLAST Mission Operations Center

GBM Data Sets

GBM IOC

Alerts, Telemetry

SPACE

NETWORK

Real-time telemetry

Commands, TOO, Loads

Mission

Operations Center

Selected Playback Tlm

Schedules

Commands, Loads

Status

As flown timelines

Orbit Data

GBM Alerts

  • Mission Scheduling

  • Commanding

  • Observatory safety

  • Spacecraft health

  • Orbit Prediction

  • Alert message routing

  • GBM Data Handling

  • Data Distribution

  • Instrument Health

LAT Data Sets

Real-time Telemetry

LAT IOC

GROUND

STATION

NETWORK

Real-time telemetry

GBM, Playback,S/C tlm

Selected Playback Tlm

Commands, Loads

Commands, Loads

Schedules

As flown timelines

Status

LAT Alerts

Acquisition Data

GRB

COORDINATES

NETWORK

SSC

Schedules

S/C data for archiving

As flown timelines

Burst/Transient

Alerts

TOO


References

References

  • 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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