1. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 1 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

2. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 2 Mission Operations Architecture GRB Coordinates Network Mission Ops Center Observatory safety Spacecraft health Commanding Mission scheduling Instrument data handling LAT Instrument Operations Center LAT data handling LAT performance Standard product processing Science Support Center Science scheduling Archiving Guest Observer Support Standard product processing GBM Instrument Operations Center GBM data handling GBM performance Standard product processing Burst and transient Alerts Large loads Target of Opportunity Commands Routine Data and commands Spacecraft, IOC, and GBM data Standard products Schedule requests Standard products Schedule requests LAT Data Command Loads Status GBM Data Status Command Loads Five contacts per day Alerts GLAST TDRSS Malindi Level 0 data for archiving Schedules White Sands

3. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 3 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

4. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 4 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

5. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 5 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.

6. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 6 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

7. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 7 GLAST Science Data Flow 5 contacts/day 6-7 minutes each 15 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 spacecraft Recorded GBM data Recorded LAT data Level Zero Processing GBM Instrument Operations Center Science Support Center Higher level Processing Archiving Data Distribution Real time GBM H&S Recorded GBM Data Real time or playback S/C (as requested) Spacecraft Level 0GBM level 0 GBM Level 1 GBM standard products LAT level 0 LAT Level 1 LAT standard products Real time LAT H&S Recorded 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 higher Level processing Malindi 28 Gbits/day 1 GBM 1 Spacecraft 26 LAT

8. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 8 Schedule and Command Data Flows 5 contacts/day 2 kbps Mission Operations Center LAT Instrument Operations Center GBM Instrument Operations Center Science Support Center Command Loads GBM S/W Loads GBM Schedule Request LAT Schedule Request Command Loads LAT S/W Loads Large Loads Target of Opportunity Commands Commands Target of Opportunity Request Instrument Activity Schedule Instrument/Science Scheduling Target of Opportunity Selection GBM Scheduling GBM instrument S/W GBM Command Generation LAT Scheduling LAT instrument S/W LAT Command Generation Spacecraft Command Generation Load Integration and Formatting Ground Station Scheduling Planning Data Schedules Acquisition data Schedules Acquisition data As-flown timeline Malindi White Sands As-flown timeline 0.4 to 4 kbps S-band, 2kbps Command uploads - ~weekly Calibration table uploads - infrequently TDRSS MAS, 0.5 to 4kbps ToO commanding - infrequent Flight software uploads - very infrequently GLAST TDRSS

9. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 9 GLAST 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 to MOC less than 14 seconds Sorter LAT Alerts Reformat GBM Alerts Process Safety Alerts GCN LAT IOC GBM IOC LAT Data GBM Data Alerts Attitude Maneuver Notification 1 kbps for up to 5-10 minutes White Sands TDRSS GLAST

10. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 10 GLAST Observatory Operational Modes Launch Early Orbit Observatory Verification Safe –Software –Hardware –Survival –Recovery Standby/Engineering Normal Operations Re-entry Launch Mode Observatory Verification Mode Early Orbit Mode Normal Operations Mode Standby/ Engineering Mode Re-entry Mode Safe Mode Survival Mode Hardware Mode Software Mode Safe Mode Recovery

11. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 11 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.

12. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 12 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

13. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 13 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

14. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 14 Background Material

15. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 15 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 Overview

16. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 16 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).

17. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 17 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.

18. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 18 ASINet Central Node Fucino, Italy Prime - 2 Mbps Intelsat Backup - 500 kbps Malindi gets ~35 Gbits per day from GLAST and 26 Gbits From Swift, and AGILE Equivalent to ~400 kbps continuous JSC Houston MOC (TBD) LAT IOC Stanford 32 Mbps NISN or ASINet 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 Data Followed by processed Level 0 Data Malindi NISN or Internet 2 via ARC LAT Data Path Realtime data: 32 kbps S-band SSR dump: 15 Mbps X-band

19. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 19 LAT 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 Verification  LAT Health & Safety Monitoring  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 Processing  Optimizing Analysis & Processing Algorithms  LAT Calibration  LAT Performance Assessment  Data Distribution  Analysis Software  Mirror 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

20. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 20 GLAST Mission Operations Center SPACE NETWORK GRB COORDINATES NETWORK SSC LAT IOC GROUND STATION 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

21. GLAST LAT ProjectIDT Face-to-Face Agenda S. Williams 21 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.