HMI%20Mission%20Operations

1
HMI Mission Operations

• Rock Bush
• HMI Stanford Program Manager
• Stanford University
• rbush_at_solar.stanford.edu

2
Outline

• Ground System Architecture
• Launch and Early Operations
• Instrument Checkout and Commissioning
• Coordinated Activities
• Mission Operations
• Summary

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HMI Operations Concept

• The goal of HMI operations is to achieve a
  uniform high quality data set of solar
  Dopplergrams and magnetograms.
• A single Prime Observing Sequence is run
  continuously taking interleaved images from both
  cameras. This observing sequence will be
  maintained for the entire SDO mission.
• Short HMI internal calibration sequences are run
  on a periodic basis in order to monitor
  instrument performance parameters such as
  transmission, focus, filter tuning and
  polarization.
• Every six months, coordinated spacecraft
  off-point and roll maneuvers are performed to
  determine the end-to-end instrument flat-field
  images and measure solar shape variations.
• HMI commanding requirements will be minimal
  except to update internal timelines for
  calibration activities and configuration for
  eclipses and maneuvers.

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Joint Science Operations Center

• The HMI and AIA Joint Science Operations Center
  (JSOC) is located in Palo Alto, California.
• The HMI and AIA science planning, instrument
  operations, health and safety monitoring, data
  processing and science analysis activities are
  similar to those performed by the Stanford and
  Lockheed groups for the MDI and TRACE
  instruments.
• The JSOC science planning is a collaborative
  effort of the HMI and AIA science teams with a
  major emphasis on coordinated observing.
• The JSOC instrument commanding, housekeeping
  telemetry processing and health monitoring is
  performed at the Lockheed Martin Solar and
  Astrophysics Laboratory in coordination with the
  SDO Mission Operations Center at Goddard Space
  Flight Center.
• The JSOC Science Data Processing and HMI science
  analysis is performed at Stanford University with
  high rate science data acquired from the SDO Data
  Distribution System located at White Sands, New
  Mexico.
• The ground system architecture is summarized in
  the following slide.

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SDO Ground System Architecture
Same Interfaces as Prime Ground Station
S-Band Cmd HK Tlm
Observatory Commands
Acquisition Data
Ka-Band 150 Mbps Science Data
Station Control
Housekeeping Telemetry
Tracking Data
Station Status
Ka Science Data
DDS Control
DDS Status
HMI AIA Instrument Commands and Loads
HMI Science Data 55 Mbps
Science Planning and FDS Products
HMI, AIA S/C Housekeeping Telemetry
AIA Science Data 67 Mbps
HMI and AIA Joint Science Operations Center
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HMI Early Operations

• Early Operations Support
• Science and engineering team members will be
  located at both the GSFC SDO Mission Operations
  Center and the Joint Science Operations Center.
• Launch and Early Operations
• A continuous dry nitrogen purge is maintained on
  the HMI Optics Package prior to launch.
• The HMI instrument is powered off for launch.
• The HMI survival heaters are enabled at launch.
• The HMI CCD decontamination heaters will be
  powered on immediately after the spacecraft is
  power positive.
• Orbit Circularization Period
• The HMI CCD decontamination heaters continue to
  operate during and after orbit raising.
• The HMI instrument processor and heater control
  electronics are powered on as soon as practical
  after GTO insertion. The remaining HMI
  electronics are powered on in steps as power
  availability allows.
• The instrument controlled Optics Package heaters
  are adjusted to accelerate complete out-gassing
  of the Optics Package interior.
• The HMI front aperture door remains closed until
  SDO is on station.

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HMI Checkout

• Functional Testing during Orbit Circularization
• Functional checkout of selected HMI subsystems
  including the processor, heaters and mechanisms
  is performed when commanding and telemetry
  resources are available and radiation levels
  permit.
• The ground functional test procedures are run as
  part of the on-orbit checkout.
• Camera and High Speed Data Bus Testing
• Functional testing of the Data Compression/ High
  Rate Telemetry Interfaces are performed after
  checkout of the SDO high speed bus and antenna
  system.
• The CCD cameras are powered up and extensively
  tested to verify their operation. Both dark
  images and flat field images using an internal
  light source will be obtained.
• Sunlight Testing
• After all subsystem functional testing is
  finished, the HMI front aperture door is opened
  for first light.
• A complete optics and filter system functional
  test is performed using sunlight.
• After the SDO spacecraft is operating in science
  pointing mode, the image stabilization system is
  run through an extensive checkout.

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First Month of On-Orbit Activities
AIA Guide Telescope Calibration With
Science Telescopes
SDO High Speed Bus Ready
Initial AIA Guide Telescope Calibration
SDO Solar Arrays Deployed
SDO Orbit Raising Finished
HMI First Sunlight
SDO Launch
Week 1
Week 2
Week 3
HMI CCD Decontam Heaters On
HMI Electronics Powered On
HMI Cameras Powered On
HMI CCD Decontam Heaters Off
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HMI Commissioning

• Thermal Optimization
• The HMI Optics Package temperature control is
  optimized for science operations after the
  functional testing is completed.
• Image Stabilization System Characterization and
  Tuning
• The ISS response to spacecraft disturbances is
  measured at 512 Hz and downlinked in the
  diagnostic telemetry.
• The ISS performance is evaluated and tuned to
  optimize the closed loop performance.
• Optics and Filter Characterization
• Detailed measurements of the HMI optical and
  filter performance are performed using
  calibration sequences developed during ground
  testing, and include
• Instrument transmission and focus characteristics
• Filter wavelength and uniformity
• Optical distortion, field curvature and
  astigmatism
• Temperature dependence
• Prime Sequence Testing
• Several candidate Prime Observing sequences are
  run for one to two days in order to determine
  which sequence provides the optimal science
  observations.

10
HMI Rehearsal of Coordinated Activities

• The following should be performed during the SDO
  commissioning in order to verify the operations
  scenarios
• Alignment Adjustment
• The HMI optical boresight is aligned with the SDO
  reference boresight by adjusting the HMI Optics
  Package legs.
• Performed in conjunction with the AIA guide
  telescope offset calibration and adjustment.
• Spacecraft Station Keeping / Momentum Management
• The HMI ISS loop is opened to prevent large
  excursions of the active mirror.
• The HMI front door is planned to remain open
  during maneuvers.
• Spacecraft Calibration Maneuver Testing
• Periodic spacecraft off-point and roll maneuvers
  are required for instrument calibration and
  science observation, and are based on similar
  maneuvers performed by the SOHO spacecraft.
• The off-point maneuver is used to determine the
  instrument flat-field, and requires 5 minute
  dwells at 15 to 20 positions on the solar disk.
• A 360º roll maneuver about the SDO X axis is
  essential to determining the solar shape, and
  requires 15 minute dwells at 16 evenly spaced
  roll angles.

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HMI Mission Operations

• Nominal Operations
• Nominal operations begin at the completion of the
  commissioning activities.
• A single Prime Observing Sequence is run
  continuously taking interleaved images from both
  cameras. This observing sequence will be
  maintained for the entire SDO mission.
• Eclipse Operations
• Temperature perturbations caused by the periodic
  eclipses of the SDO orbit is minimized by active
  thermal control of the HMI Optics Package
  including the front window.
• The image stabilization system loop is opened
  prior to eclipse entry and closed after eclipse
  exit, and will be initiated by stored time tagged
  commands.
• Daily Calibrations
• A daily set of images is taken in HMI
  calibration mode to monitor instrument
  transmission and CCD performance.
• This sequence runs for one to two minutes, and is
  scheduled as part of the nominal observing
  timeline.
• Bi-Monthly Calibrations
• Approximately every two weeks, an extended
  calibration sequence is run for about one hour
• Sequences are run to provide measurements of the
  instrument focus, filter and polarization
  characteristics.
• Performance Tracking and Anomaly Resolution
• Trending of instrument performance is planned as
  an integral part of mission operations.
• Anomalies in subsystem operation are documented
  and resolved.

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Summary

• Implementation of the HMI mission operations and
  ground system development is being coordinated
  with the SDO project.
• A Mission Operations Plan and Instrument On-orbit
  Commissioning Plan are being developed.
• End-to-end testing between the JSOC and the
  flight instrument are planned as part of the
  spacecraft integration activities.
• Detailed requirements for the Science Sequencer
  are being finalized.
• A software sequencer simulator is being developed
  in order to verify and optimize the observing
  sequences.
• Several candidate Prime Observing Sequences are
  being developed to assess their scientific
  performance and impact on instrument resources.
• Calibration sequences are being developed to
  characterize the HMI instrument performance
  during ground test and integration. Similar
  calibration sequences are used for the periodic
  on-orbit calibration.