11 SpaceOps 2002

Autonomous Operations For The Swift Mission

T3-47

John Ong/Swift Software Systems ManagerNASA/GSFC Code 582/301-286-8435

Mike Rackley/Swift Ground System EngineerNASA/GSFC Code 581/301-286-5528

22 SpaceOps 2002

Major Mission Goals

• Autonomously Detect & Observe Of Gamma-Ray Bursts (GRBs)

• Autonomously Slew To (I.e., “Chase”) GRBs (w/o Ground Intervention)

• Forward GRB Data (e.g., Position, Basic Characteristics) to Ground System Within 20 Seconds

• Perform Hard-X-Ray Survey (Through Pre-Scheduled, Time-Based Observation Plan)

• Perform Follow-On Observations (Through Continual Updating of Observation Plan)

• Quickly And Autonomously Distribute Newly Detected GRB Information To The Global Astronomy Science Community

33 SpaceOps 2002

Observatory Overview

X Z

Y

BAT

UVOTSun Shade

XRT

Star Trackers

XRT radiator

BAT Power Box

BAT IPE Boxes

IRUs

44 SpaceOps 2002

Mission Characteristics

• Autonomous Slew Decision Capability • Fast Slews: 50° in <75 seconds

• Low Earth Orbit, 22° Inclination

BAT(Burst Alert Telescope)

XRT(X-Ray Telescope)

UVOT(Ultra-Violet Optical Telescope)

Position Accuracy 5 arcmin 5 arc seconds 0.3 arc secondsEnergy Range 15 keV to 150 keV 200 eV to 10 keV 170 to 650 nm WavelengthFOV 2 Steradians 23.6 x 23.6 arc minutes 17 x 17 arc minutesPSF HPD 17 arcmin 15" @ 1.5 keV 0.9" @ 350 nm

Effective Area (cm2) 5200 110 @ 1.5 keV

Telescope ~4 ft x 8 ft Coded Mask Wolter I, 12 shells30 cm Aperture Modified Ritchey-

ChretienFocal Length 1 m 3.5 m F12.7Timing Resolution 100 micro-sec 1 secDetector 32,000 individual CZT MAT CCD-22 (EEV) Intesified CCDDetector Format 128 pixels/DM, 256 DMs 600 x 600 pixels 256 x 256 pixels

Sensitivity 0.2 photons/cm2/sec 2x10

-14 erg-cm

-2-s

-1 (10

4 sec) B=24.0 (White light, 1000 sec)

Detector Modes Burst, Survey Photon Counting, Imaging, Timing Photon Counting

• Delta II 2420-10, 3m Fairing

• Observatory Mass: ~1357 kg

• Average Power: ~983 W

55 SpaceOps 2002

Key Mission Ops Challenges

• Supporting 24x7 “Dynamic”, Autonomously Slewing S/C With An 8x5 Ops Staff– Observation of a Newly Detected GRB Causes Rescheduling of

Observing Plan (Expected to Occur Daily)

• Generating Accurate As-Flown Schedule Given That The Pre-Planned Schedule Will Change Routinely– Utilizes Unique Observation Ids To Enable Mapping of As-Flown

Schedule To Actual Observations

• Performing Data Processing With Minimal Staff– From Raw-Frame Files At Ground Station To Science Formatted

Files At Data Center

66 SpaceOps 2002

Operations Concept Summary

• Autonomous GRB Detection & Repointing of S/C By Onboard Figure of Merit (FoM) Flight SW (FSW)– Occurs Approximately Once Per Day– Immediate Notification to Ground System So Others In Science

Community Can Also Take Action to View Burst

• When Not Viewing a Newly Detected Burst, Spacecraft is Driven by Pre-Loaded Observation Plan– 72-Hour Observation Plan Uplinked Daily

• For Newly Detected and Preplanned Bursts, All Observations Assigned a Unique Observation Number– Information on Actual Observations Reflected In FoM FSW

Housekeeping (Observation Numbers, Times, Durations, etc.) – Ground System Develops As-Flown Schedule Using

Observation Information Provided by FoM FSW

77 SpaceOps 2002

Operations Concept Summary

• Frequent, Dynamic Replanning Performed by Science and Flight Operations Teams– Must Account for Previous Preplanned Activities (Observation

Plan), and How They Were Affected by the Autonomous Actions Taken by the Spacecraft (Newly Detected Bursts)

• Routine Spacecraft Communications With Ground Station– Approximately 6-10 Contacts Per Day (6 Minimum)– Contacts Used For Routine Operations (e.g., Data Dumps, Health

and Safety Monitoring, Daily Commanding)

• Process for Getting Data from Malindi to the Science Users Quickly Fully Automated

• Science Team Able to Initiate Observations Quickly Via Target of Opportunity (ToO) Requests

88 SpaceOps 2002

System Architecture Diagram

White Sands Complex (WSC)MalindiGround Station

SWIFTTDRS

S-Band CMD/TLM2.25 Mbps downlink (RT & PB TLM)

2 kbps uplink (Normal Commanding)

NCC

MissionOperations Center

(MOC)

SwiftData Center

Commands

Command, H/K, Science

PSU

GSFC

JSC

OpticalTelescopes

RadioTelescopes

Quick-look L0 Data

Prod.FITS data

Observation Requests

Observation Results

e.g. Chandra

e.g. HET

e.g. VLA

Alerts, TOO Commanding,Contingency H/K,Tracking

SwiftScience Center

Data Analysis Tools

Alerts,H/K

HEASARC

GSFCGSFC

November 13, 2001 Revision J

GCN

GSFC

Front-End

MAF/MAR&DAS CMD/TLM1 kbps downlink (Alerts & H/K)

125 bps uplink (ToORequests)

SN Scheduling & Status

Burst Alerts

Satellites

Science Teams,

Community

ISAC

UKDC

2-Line Elements

BAT

UVOT/XRT

Flight Software

Maintenance

Spacecraft

GSFC

PSUSpectrum Astro

Flight DynamicsFacility

GSFC

Orbit Data

NORAD

Tracking Data

Kenya

ASINetFucinoGateway

Fucino, Italy

ASINet US Gateway

384 kbps Leased Line

Quick-look Data & Products

S/W UpdatesObservatoryData

White Sands Complex (WSC)MalindiGround Station

SWIFTTDRS

S-Band CMD/TLM2.25 Mbps downlink (RT & PB TLM)

2 kbps uplink (Normal Commanding)

NCC

MissionOperations Center

(MOC)

SwiftData Center

Commands

Command, H/K, Science

PSU

GSFC

JSC

OpticalTelescopes

RadioTelescopes

Quick-look L0 Data

Prod.FITS data

Observation Requests

Observation Results

e.g. Chandra

e.g. HET

e.g. VLA

Alerts, TOO Commanding,Contingency H/K,Tracking

SwiftScience Center

SwiftScience Center

Data Analysis Tools

Alerts,H/K

HEASARC

GSFCGSFC

November 13, 2001 Revision J

GCN

GSFC

Front-End

MAF/MAR&DAS CMD/TLM1 kbps downlink (Alerts & H/K)

125 bps uplink (ToORequests)

SN Scheduling & Status

Burst Alerts

Satellites

Science Teams,

Community

ISAC

UKDC

2-Line Elements

BAT

UVOT/XRT

Flight Software

Maintenance

Spacecraft

GSFC

PSUSpectrum Astro

BATBAT

UVOT/XRTUVOT/XRT

Flight Software

Maintenance

Spacecraft

GSFC

PSUSpectrum Astro

Flight DynamicsFacility

GSFC

Orbit Data

NORADNORAD

Tracking Data

Kenya

ASINetFucinoGateway

Fucino, Italy

ASINet US Gateway

384 kbps Leased Line

Quick-look Data & Products

S/W UpdatesObservatoryData

99 SpaceOps 2002

System Architecture Highlights

• Burst Alert Messages Relayed to Ground in Real-Time Via the TDRSS Demand Access Service (DAS)– DAS Provides Near Continuous Coverage– Messages Relayed to GRB Coordinates Network (GCN) For

Distribution to the Science Community in Near Real-Time– Link May Also Be Used to Provide Housekeeping Data to

Operations Team in the Mission Operations Center (MOC)

• Malindi Ground Station Provides Ability to Dump Stored Housekeeping & Science Data to Ground and Conduct Day-to-Day Operations– Station Owned and Operated by Italian Space Agency (ASI) and

Located in Kenya, Africa– Dump Data Automatically Transmitted to the MOC

1010 SpaceOps 2002

System Architecture Highlights

• Science Team Can Add Target-Of-Opportunity (ToO) Requests To Observation Plan– Science Team Presents ToO Request To MOC– MOC Uplinks Via TDRSS - Uplink Must Be Scheduled, Not Always

Available Like The DAS for Telemetry– Turnaround Within 60 Minutes

• Swift Data Center Provides Science Data Processing Functions– Receives Data Automatically From the MOC– Extracts Observations From Raw Packet Data– Converts Observations Into Science Formatted, Quick-Look Data

Products and Makes Available to the User Community– Data Processing Pipeline Fully Automated

1111 SpaceOps 2002

System Architecture Highlights

• Flight Operations Support in MOC Supported Via Standard Suite Of Automation Capabilities/Tools– Automatic Conduct Of Data Dumps From Spacecraft– Autonomous Monitoring Of Telemetry With Paging Of Offsite Personnel

As Needed– Remote Data Access For Flight Operations Team– Automatic Ingest Of Orbit Information And Incorporation Into Planning

Process– Automatic Generation of Analysis Products (e.g., Trend Plots And

Statistics Reports)

1212 SpaceOps 2002

Onboard Autonomy Via FoM FSW

• FoM FSW Schedules Actual Observations– Pre-Planned Targets (PPTs) Uplinked In Observation Plan Are

Forwarded to FoM FSW ILO S/C ACS

– Automated Targets (ATs) Consist Of Newly Detected GRBs & ToOs

– Priority of Observations Based On Assigned Merit

– Observing PPTs Given Priority When ATs Constrained

• FoM FSW Scheduling Requires Integrating Time-Based PPTs and Event-Based ATs– ATs Are To Be Observed ASAP for Pre-Defined Time

– PPTs Can Be Pre-Empted By ATs

• BAT Assigns Observation Numbers for GRBs, Ground System Assigns For PPTs and ToOs

1313 SpaceOps 2002

FoM FSW Target Observation Flow

PPT request Burst Event Uplink ToO

ScheduledPPT

CandidateAT

FoM PPT FoM AT

ObservedTarget

From Ground(via SCP)

From BATFrom Ground(via TDRSS)

• The unique capability which distinguishes Swift from all other astrophysics missions is the requirement to slew the spacecraft to acquire the newly discovered GRBs within the field of view of the Narrow-Field Instruments

• The scientific premium on rapid acquisition is so high as to preclude ground control of the slew request, so the Swift spacecraft must include an onboard decision process to enable an entirely automated response to unplanned slew requests (hence, the Figure of Merit)

1414 SpaceOps 2002

FoM FSW Functional Interfaces

S/C

ATT STATUS PKT

SLEW RESPONSE MSG

VIEW CONSTRAINT MSG

S/C

SLEW REQUESTS

Ground

PPT REQUEST (via SCP)

ToO REQUEST (via TDRSS)

FoM MGMT CMDS

Ground

TDRSS MSGs

FoM TLM PKTs

Figureof

Merittask

HSKP PKT REQUEST

MERIT UPDATE MSG

Instr

BAT

NFIs

NEXT OBSERVATION INFO MSG

Inst

BAT

NFIs

GRB POSITION MSG

1515 SpaceOps 2002

Conclusions

• Swift Represents A New Class of Missions Requiring Autonomous S/C Repointing Without Ground Intervention– Not Possible For FOT To Be In Loop For Authorizing “Chasing” of GRBs– Onboard FoM FSW Will Manage Autonomous Slews - FOT Reassess and

Replans Accordingly

• Vital That Ground Systems Work With Flight Data Systems Engineers Early-On To Ensure Capabilities Exists For Efficient & Cost-Effective Operations– Every PPT and AT Observation Assigned Unique Observation Number,

Allowing for Correlation of Instrument Science Data– Actual Observation Information Downlinked In FoM Housekeeping

Essential to Generation of As-Flown Schedule

• High Level of Automation of Data Processing Pipeline Required To Meet Funding Limits– Close Coordination Required Among Instrument, S/C, Malindi Ground

Station, MOC, & SDC Personnel