Launch and On-orbit Checkout Rock Bush HMI Stanford Program Manager Stanford University rbush@solar.stanford.edu 650-723-8162

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

SDO Mission Operations Center SDO Ground System Architecture S band Ground System Ka band SDO Ground Site #2 White Sands Same Interfaces as Prime Ground Station S-Band: Cmd & HK Tlm S band Ground System Ka band SDO Ground Site #1 White Sands Observatory Commands Flight Dynamics System SDO Mission Operations Center Telemetry & Command Ground Station Control System DDS Control System Mission Planning Trending Acquisition Data Ka-Band: 150 Mbps Science Data Station Control Housekeeping Telemetry Tracking Data Station Status Ka Science Data Data Distribution System DDS Control DDS Status HMI & AIA Instrument Commands and Loads HMI Science Data 55 Mbps Science Planning and FDS Products AIA Science Data 67 Mbps HMI, AIA & S/C Housekeeping Telemetry Stanford University Science Data Processing Lockheed Martin Instrument Operations HMI and AIA Joint Science Operations Center

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”.

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.

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 SDO Launch Week 1 Week 2 Week 3 HMI Electronics & Mechanisms Checkout HMI CCD Cameras Checkout HMI Optics, Filters & ISS Checkout HMI CCD Decontam Heaters On HMI CCD Decontam Heaters Adjusted to 0 °C HMI First Sunlight HMI CCD Decontam Heaters Off HMI Electronics Powered On HMI Cameras Powered On

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.

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.

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.

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.