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HMI Mission Operations

HMI Mission Operations

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HMI Mission Operations

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  1. HMI Mission Operations Rock Bush HMI Stanford Program Manager Stanford University rbush@solar.stanford.edu

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

  3. 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.

  4. 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.

  5. SDO Ground Site #2 White Sands S band Ground System Ka band Ground System SDO Ground Site #1 White Sands SDO Mission Operations Center Telemetry & Command System S band Ground System Flight Dynamics System Ka band Ground System Ground Station Control System Mission Planning Trending DDS Control System Data Distribution System Stanford University Science Data Processing Lockheed Martin Instrument Operations 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

  6. 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”.

  7. 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.

  8. HMI CCD Cameras Checkout HMI Electronics & Mechanisms Checkout HMI Optics, Filters & ISS Checkout 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 Week 1 Week 2 Week 3 SDO Launch HMI CCD Decontam Heaters On HMI Electronics Powered On HMI Cameras Powered On HMI CCD Decontam Heaters Off

  9. 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.

  11. 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.

  12. 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.