Solar Dynamics Observatory HMI Stanford University Advanced Technology
Solar Dynamics Observatory HMI Stanford University Advanced Technology Center Solar Dynamics Observatory System Concept Review Helioseismic and Magnetic Imager Draft Presentation 21 March 2003 Stanford University Hansen Experimental Physics Laboratory Stanford, CA SDO System Concept Review Lockheed Martin Space Systems Company Advanced Technology Center Solar & Astrophysics Laboratory Palo Alto, CA HMI - Scherrer 1
HMI Science Objectives Stanford University Advanced Technology Center B – Solar Dynamo J – Sunspot Dynamics I – Magnetic Connectivity C – Global Circulation A – Interior Structure D – Irradiance Sources H – Far-side Imaging E – Coronal Magnetic Field NOAA 9393 Far-side G – Magnetic Stresses SDO System Concept Review F – Solar Subsurface Weather HMI - Scherrer 2
Top Down View of HMI Science Requirements HMI Stanford University Advanced Technology Center NAS/NRC and NASA Roadmap Living With a Star SDO Mission HMI Investigation HMI Science Objectives HMI Science Data Products HMI Observations HMI Observables HMI Instrument Data HMI Instrument Concept HMI Instrument Requirements HMI - SDO interface SDO S/C Concept Ground System SDO System Concept Review HMI - Scherrer 3
HMI Science Objectives HMI Stanford University Advanced Technology Center • Convection-zone dynamics and the solar dynamo • Origin and evolution of sunspots, active regions and complexes of activity • Sources and drivers of solar activity and disturbances • Links between the internal processes and dynamics of the corona and heliosphere • Precursors of solar disturbances for space-weather forecasts – – – – – Structure and dynamics of the tachocline Variations in differential rotation Evolution of meridional circulation Dynamics in the near surface shear layer Formation and deep structure of magnetic complexes of activity Active region source and evolution Magnetic flux concentration in sunspots Sources and mechanisms of solar irradiance variations Origin and dynamics of magnetic sheared structures and d-type sunspots Magnetic configuration and mechanisms of solar flares Emergence of magnetic flux and solar transient events Evolution of small-scale structures and magnetic carpet Complexity and energetics of the solar corona Large-scale coronal field estimates Coronal magnetic structure and solar wind Far-side imaging and activity index Predicting emergence of active regions by helioseismic imaging Determination of magnetic cloud Bs events SDO System Concept Review HMI - Scherrer 4
HMI Science Data Products HMI Stanford University Advanced Technology Center • HMI Science Data Products High-level data products which are input to the science analyses. These are time series of maps of physical quantities in and on the Sun. – – – – Internal rotation Ω(r, Θ) (0<r<R) Internal sound speed, cs(r, Θ) (0<r<R) Full-disk velocity, v(r, Θ, Φ) and sound speed, cs(r, Θ, Φ) maps (0 -30 Mm) Carrington synoptic v and cs maps (0 -30 Mm) High-resolution v and cs maps (0 -30 Mm) Deep-focus v and cs maps (0 -200 Mm) Far-side activity index Line-of-Sight Magnetic field maps Vector Magnetic Field maps Coronal magnetic Field extrapolations Coronal and Solar wind models Brightness Images Context Magnetograms SDO System Concept Review HMI - Scherrer 5
HMI Science Analysis Pipeline Stanford University Advanced Technology Center HMI Data Processing Global Helioseismology Processing Filtergrams Local Helioseismology Processing Data Product Internal rotation Ω(r, Θ) (0<r<R) Internal sound speed, cs(r, Θ) (0<r<R) Science Objective Tachocline Meridional Circulation Differential Rotation Full-disk velocity, v(r, Θ, Φ), And sound speed, cs(r, Θ, Φ), Maps (0 -30 Mm) Near-Surface Shear Layer Carrington synoptic v and cs maps (0 -30 Mm) Active Regions Activity Complexes Sunspots Observables High-resolution v and cs maps (0 -30 Mm) Doppler Velocity Deep-focus v and cs maps (0 -200 Mm) Magnetic Shear Far-side activity index Flux Emergence Line-of-Sight Magnetic Field Maps Magnetic Carpet Line-of-sight Magnetograms Vector Magnetograms Continuum Brightness Vector Magnetic Field Maps Coronal magnetic Field Extrapolations Coronal and Solar wind models Brightness Images SDO System Concept Review Irradiance Variations Flare Magnetic Configuration Coronal energetics Large-scale Coronal Fields Solar Wind Far-side Activity Evolution Predicting A-R Emergence IMF Bs Events Version 1. 0 w HMI - Scherrer 6
HMI Observables Requirements HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 7
HMI Observables Requirements HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 8
HMI Observables Requirements HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 9
HMI Source of Requirements Stanford University Advanced Technology Center • • HMI Investigation HMI Science Objectives – – – Duration of mission Completeness of coverage HMI Science Data Products Roll accuracy Time accuracy (months) HMI Observations – – – • Duration of sequence Cadence Completeness (95% of data sequence) Noise Resolution Time accuracy (days) • • HMI Observables – – – – Sensitivity Linearity Acceptable measurement noise Image stability Time rate (minutes) Completeness (99. 9% of observable data in 90 s) Orbit knowledge SDO System Concept Review • • HMI Instrument Data – – – – Accuracy Noise levels Completeness (99. 99% of data in filtergram) Tuning & shutter repeatability Wavelength knowledge Image registration Image orientation jitter HMI Instrument Concept – – Mass Power Telemetry Envelope Sub-system requirements – – – CCD: Thermal environment ISS: pointing drift rate, jitter Legs: pointing drift range HMI to SDO Interface Requirements Ground System Processing System Data Distribution HMI - Scherrer 10
Key Requirements HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 11
HMI Instrument Concept HMI Stanford University Advanced Technology Center • • • The HMI instrument is an evolution of the successful Michelson Doppler Imager instrument which has been operating on the SOHO spacecraft for over seven years. The raw HMI observables are filtergrams of the full solar disk taken with a narrow band (~ 0. 1 A bandpass) tunable filter in multiple polarizations. The primary science observables are Dopplergrams, line-of-sight magnetograms, vector magnetograms and continuum images computed from a series of filtergrams. Some of the key instrument design drivers include maintaining uniform image quality and performance through detailed optical and thermal design and rigorous testing. The vector magnetic field measurements are best decoupled from the helioseismology measurements, and a two camera design results to maintain image cadence and separate the two primary data streams. SDO System Concept Review HMI - Scherrer 12
HMI Optical Layout HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 13
HMI Optics Package Layout HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 14
HMI Design Improves on MDI HMI Stanford University Advanced Technology Center • The HMI common design features based on MDI: – – – • Front window designed to be the initial filter with widest bandpass. Simple two element refracting telescope. Image Stabilization System with a solar limb sensor and PZT driven tip-tilt mirror. Narrow band tunable filter consisting of a multi-element Lyot filter and two Michelson interferometers. Similar hollow core motors, filterwheel mechanisms and shutters. The HMI improvements from MDI: – The observing line is the Fe I 617. 3 nm absorption line instead of the Ni I 676. 8 nm line. This observing line is used for both Doppler and magnetic measurements. – Rotating waveplates are used for polarization selection instead of a set of polarizing optics in a filterwheel mechanism. – An additional tunable filter element is included in order to provide the measurement dynamic range required by the SDO orbit. – The CCD format will be 4096 x 4096 pixels instead of 1024 x 1024 pixels in order to meet the angular resolution requirements. – Two CCD cameras are used in parallel in order to make both Doppler and vector magnetic field measurements at the required cadence. – The is no image processor – all observable computation is performed on the ground. SDO System Concept Review HMI - Scherrer 15
HMI Subsystems Stanford University Advanced Technology Center • Optics Package Structure – • • • Optics Subsystem – • • Includes all the optical elements except the filters Filter subsystem – – The filter subsystem includes all the filters and Michelsons Provides the ability to select the wavelenght to image Thermal Subsystem – – Controls the temperature of the optics pkg. , the filter oven, CCDs, and the front window. Implements the decontamination heating of the CCD. Image Stabilization Subsystem – – Consists of active mirror, limb sensor, precision digital & analog control electronics It actively stabilizes the image reducing the effects of jitter Mechanisms Subsystem – • The optic package structure subsystem includes the optics package structure, the mounts for the various optical components and the legs that mount the optics package to the spacecraft. The mechanisms subsystem includes shutters, hollow-core motors, calibration/focus wheels, alignment mechanism, and the aperture door CCD Camera Subsystem – The CCD camera subsystem includes 4 Kx 4 K CCDs and the camera electronics box(es) HMI Electronics Subsystem – Provides conditioned power and control for all HMI subsystems as well as HMI C&DH hardware Software Subsystem – The software subsystem includes the C&DH interface to the spacecraft and controls all of the other HMI subsystems SDO System Concept Review HMI - Scherrer 16
HMI Functional Block Diagram Stanford University Advanced Technology Center PWB Mechanism && Mechanism heater controllers Heater Controllers Camera Electronics Box PWB Camera data PWB Data compressor Data Compressor / & Buffer AEC Buffer memory Spacecraft Interface ISS (Limb tracker) Image Stabilization System Limb Sensor & Active Mirror Buffer memory Buffer Memory (2 x 4 K x 16) (2 x 4 Kx 16) ISS data PWB Control Optics Package SDO System Concept Review PC/local bus bridge/ Bus Bridge EEPROM PWB ISS (PZT drivers) PWB Housekeeping data acquisition Data Acquisition PWB Central Processor/ Central processor EEPROM PCI Bus Mechanisms: Focus/Cal Wheels (2) Polarization Selectors (3) Tuning Motors (4) Shutters (2) Front Door Alignment Mechanism Filter Oven Control Structure Heaters Housekeeping Data SDOSDO Spacecraft DC DC - DC power - DC Power Converter converter Camera interface Interface (SMClite) ) ( SMClite Control Housekeeping ADC, Housekeeping & Master Clock & master clock LVDS Control CCD IEEE 1355 Control CCD Driver Card (2) Clock & sequencer CDS/ADC Command / Data Interface CCD PWB Power Converters converters Electronics Box HMI - Scherrer 17
Optics Subsystem HMI Stanford University Advanced Technology Center • 1 arc-sec diffraction limited image at the sensor – Requires 14 cm aperture – Requires 4096 x 4096 pixel sensor • Solar disk at the sensor 4. 9 cm – For sensor with 12 um pixels • • • Focus adjustment system with ± 3 (TBC) depth of focus range and 16 steps Provide calibration mode that images the pupil on the sensor Provide beam splitter to divide the telescope beam between the filter oven and the limb tracker Provide telecentric beam through the Lyot filter Provide beam splitter to feed the output of the filter subsystem to two sensors Minimize scattered light on the sensor SDO System Concept Review HMI - Scherrer 18
HMI Filter subsystem Stanford University Advanced Technology Center • • • Central wavelength 6173Å Fe I line Reject 99% of solar heat load from the OP interior Total bandwidth 76 mÅ FWHM Tunable range 500 mÅ Very high stability and repeatability required (to be quantified) The required bandwidth obtained by cascading filters as follows – – – • Front window 50Å Blocker 8Å Lyot filter (5 element 1: 2: 4: 8: 16) 306 mÅ Wide Michelson 172 mÅ Narrow Michelson 86 mÅ Tuning range requires use of three co-tuned elements – Narrowest Lyot element – Wide Michelson – Narrow Michelson SDO System Concept Review HMI - Scherrer 19
MDI Lyot Elements and Michelson Interferometers HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 20
HMI Thermal Subsystem Stanford University Advanced Technology Center • Optics package thermal control – Operating temperature range 15 to 25 °C – Active control to ± 0. 5 °C – Control loop in software • Filter oven – – – • Operating temperature range 35 ± 4 °C Temperature accuracy 0. 5 °C Temperature stability 0. 01 °C /hour Changes in internal temperature gradients as small as possible Dedicated analog control loop in controlled thermal environment Sensor (CCD detector) thermal control – Operating – 100 °C to – 30 °C – Stability over an orbit xx °C? – Decontamination mode raise CCD to 20 to 40 °C (may need to be wider because of unregulated power) • Front window thermal control – Minimize radial gradients – Return to normal operating temperature within 60 minutes of eclipse exit SDO System Concept Review HMI - Scherrer 21
Image Stabilization Subsystem HMI Stanford University Advanced Technology Center • • Stability (over TBC second period) 0. 1 arc-sec Range ± 14 arc-sec Frequency range 0 to 50 Hz Continuous operation for life of mission SDO System Concept Review HMI - Scherrer 22
Mechanisms (1 of 2) HMI Stanford University Advanced Technology Center Shutters • Repeatability • Exposure range • Knowledge • Life (5 year) 100 us 50 ms to 90 sec 30 us 40 M exposures Hollow core motors • Move time (60 deg) • Repeatability • Accuracy • Life (5 year) <800 ms 60 arc-sec 10 arc-min 80 M moves SDO System Concept Review HMI - Scherrer 23
Mechanisms (2 of 2) HMI Stanford University Advanced Technology Center Calibration / focus wheels • Positions • Move time (1 step) • Accuracy • Repeatability • Life (5 Years) 5 800 ms XX arc-min 20 K moves Alignment system • Movement range • Step size ± 200 arc-sec 2 arc-sec Aperture door • Robust fail open design SDO System Concept Review HMI - Scherrer 24
CCD Camera Subsystem HMI Stanford University Advanced Technology Center • • Format Pixel size Full well Readout noise Readout time Digitization Dark current SDO System Concept Review 4096 x 4096 pixels 12 um >125 K electrons 40 electrons <3. 4 seconds 12 bits 10 –e/sec/pixel at – 60 °C HMI - Scherrer 25
HMI Electronics Subsystem Stanford University Advanced Technology Center • • Provide conditioned power and control for all HMI subsystems Provide processor for: – – – • • Control all of the HMI subsystems Decoding and execution of commands Acquire and format housekeeping telemetry Self-contained operation for extended periods Program modifiable on-orbit Provide stable jitter free timing reference Provide compression and formatting of science data Provide interface for 55 Mbps of science date Provide spacecraft 1553 interface – Commands – Housekeeping telemetry – Diagnostic telemetry SDO System Concept Review 2. 5 kbps 10 kbps (when requested) HMI - Scherrer 26
HMI Operations Concept HMI Stanford University Advanced Technology Center • • • The goal of HMI operations is to achieve a uniform high quality data set of solar Dopplergrams and magnetograms. A single “Prime Observing Sequence” will run continuously taking interleaved images from both cameras. The intent is to maintain this observing sequence for the entire SDO mission. Short calibration sequences are run on a periodic basis (daily or weekly) in order to monitor instrument performance parameters such as focus, filter tuning and polarization. Every six months, coordinated spacecraft 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. After instrument commissioning, it is anticipated that a single daily command load will be sufficient. SDO System Concept Review HMI - Scherrer 27
HMI Dataflow Concept HMI Stanford University Advanced Technology Center } Pipeline SDO System Concept Review HMI - Scherrer 28
HMI Data Analysis Pipeline Stanford University Advanced Technology Center Data Product Processing HMI Data Heliographic Doppler velocity maps Filtergrams Doppler Velocity Tracked Tiles Of Dopplergrams Spherical Harmonic Time series To l=1000 Mode frequencies And splitting Ring diagrams Local wave frequency shifts Time-distance Cross-covariance function Wave travel times Egression and Ingression maps Wave phase shift maps Internal rotation Ω(r, Θ) (0<r<R) Internal sound speed, cs(r, Θ) (0<r<R) Full-disk velocity, v(r, Θ, Φ), And sound speed, cs(r, Θ, Φ), Maps (0 -30 Mm) Carrington synoptic v and cs maps (0 -30 Mm) High-resolution v and cs maps (0 -30 Mm) Deep-focus v and cs maps (0 -200 Mm) Far-side activity index Stokes I, V Line-of-sight Magnetograms Stokes I, Q, U, V Full-disk 10 -min Averaged maps Vector Magnetograms Fast algorithm Tracked Tiles Vector Magnetograms Inversion algorithm Coronal magnetic Field Extrapolations Tracked full-disk 1 -hour averaged Continuum maps Solar limb parameters Coronal and Solar wind models Brightness feature maps Brightness Images Continuum Brightness SDO System Concept Review Line-of-Sight Magnetic Field Maps Vector Magnetic Field Maps Version 1. 2 w HMI - Scherrer 29
HMI Completed Trade Studies Stanford University Advanced Technology Center • Observing Wavelength – 6173 Å vs. 6768 Å: 6173 Å selected • CPU – RAD 6000 vs. RAD 750 vs. Coldfire: RAD 6000 selected (from SXI) • High-Rate Telemetry Board – Single Board or to include a redundant board: Redundant concept selected • Sensor Trade – CMOS vs. CCD Detector: CCD selected SDO System Concept Review HMI - Scherrer 30
HMI Trade Studies In Progress Stanford University Advanced Technology Center • Inclusion of redundant mechanisms in HMI Optic Package – Increased reliability vs. Increased cost & mass – Have allocated volume to not preclude additional mechanisms • Inclusion of redundant power supply in HMI Electronics Box – Increased reliability versus Increased cost and mass – Just started this trade • Camera Subsystem - evaluating two options – Build in-house an evolution of a Solar-B FPP Camera – Procure from RAL an evolution of a SECCHI Camera • CCD Configuration – Evaluating operation in front side or back side illuminated mode SDO System Concept Review HMI - Scherrer 31
HMI CCD and Camera Electronics Stanford University Advanced Technology Center • • • Baseline CCD vendor is E 2 V – Specification drafted - includes capabilities that allow more optimal camera electronics design and requires less power – SHARP and HMI to use identical CCDs – E 2 V to be given a design phase contract ASAP Two principal paths for development of camera electronics – Develop cameras in-house => evolution of the Solar-B FPP FG camera – Procure cameras from RAL => evolution of the SECCHI camera Key Considerations for decision on approach – Schedule => very critical – Cost => RAL approach less expensive if already doing SHARPP cameras – Performance => both “good enough” but RAL better Recommendations if camera electronics are procured from RAL – Baseline same camera for SHARPP and HMI – Have separate RAL subcontracts from LMSAL and NRL – Continue to study FPP-option through Phase A Recommendation if camera electronics are developed in house – Do not provide cameras for SHARPP – Keep informed on RAL-for SHARPP camera status and vice versa SDO System Concept Review HMI - Scherrer 32
Current Optics Package – 3 D view HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 33
HMI Optics Package Layout HMI Stanford University Advanced Technology Center Current Layout Envelope (20 Mar 2003) X= 1114 mm Y= 285 mm Z= 696 mm Y X Z Origin SDO System Concept Review HMI - Scherrer 34
HMI Electronics Box Layout HMI Stanford University Advanced Technology Center Current Layout Envelope (20 Mar 2003) X = 361 mm Y = 241 mm Z = 234 mm Y X Z SDO System Concept Review Z HMI - Scherrer 35
HMI Resources – Mass Estimates HMI Stanford University Advanced Technology Center • Mass – no margin included 20 Mar 2003 – Optics Package (OP, w/LMSAL-CEB): 35. 3 kg (TBC) – HMI Electronics Box (HEB): 15. 0 kg (TBC) – Harness: 3. 0 kg (TBC) • OP Assumptions – Includes mass of redundant mechanisms in OP – Includes larger OP for additional mechanisms, and ease of integration and alignment – 1. 5 kg mass reduction in OP possible if RAL CEBs are substituted • HEB Assumptions – – • Includes additional compression/high speed bus interface boards Includes thinned walls to account for spacecraft shielding 1 kg mass reduction in HEB power supply possible if RAL CEBs are substituted Does not include redundant power converters Harness Assumptions – Harness mass presumes a length of 2 meters SDO System Concept Review HMI - Scherrer 36
HMI Resources – Inertias & CGs HMI Stanford University Advanced Technology Center • OP 20 Mar 2003 – – Ixx: 1. 00 kg-m 2 (TBC) Iyy: 4. 30 kg-m 2 (TBC) Izz: 3. 48 kg-m 2 (TBC) these estimates are about the CG along OP axes so are therefore NOT principal axes, i. e. there also some small inertia products – CG (x, y, z) = 487 mm, 145 mm, 21 mm (TBC) • HEB 20 Mar 2003 – – Ixx: 0. 79 kg-m 2 (TBC) Iyy: 0. 22 kg-m 2 (TBC) Izz: 0. 97 kg-m 2 (TBC) these estimates presume the HEB is symmetrical about the center vertical axis so these are about principal axes through the CG, i. e. there are no inertia products – CG (x, y, z) = 180 mm, 110 mm, 98 mm (TBC) SDO System Concept Review HMI - Scherrer 37
HMI Resources - Average Power Stanford University Advanced Technology Center 1 – 10 Watt reduction possible if RAL CEB is substituted 2 – Preliminary allocation of 10 W additional heater power for window 3 – CCD decontamination heaters only (TBC) 4 – Operational heaters for OP, presume no power for HEB & CEB SDO System Concept Review HMI - Scherrer 38
HMI Resources – Mass Estimates HMI Stanford University Advanced Technology Center • Mass – no margin included 20 Mar 2003 – Optics Package (OP, w/LMSAL-CEB): 35. 3 kg (TBC) – HMI Electronics Box (HEB): 15. 0 kg (TBC) – Harness: 3. 0 kg (TBC) • OP Assumptions – Includes mass of redundant mechanisms in OP – Includes larger OP for additional mechanisms, and ease of integration and alignment – 1. 5 kg mass reduction in OP possible if RAL CEBs are substituted • HEB Assumptions – – • Includes additional compression/high speed bus interface boards Includes thinned walls to account for spacecraft shielding 1 kg mass reduction in HEB power supply possible if RAL CEBs are substituted Does not include redundant power converters Harness Assumptions – Harness mass presumes a length of 2 meters SDO System Concept Review HMI - Scherrer 39
HMI Resources - Telemetry HMI Stanford University Advanced Technology Center • Telemetry Data Rate – – Nominal science data: 55 Mbits/sec (Split between two interfaces) Housekeeping data: 2. 5 kb/sec Diagnostics data: 10 kb/sec Command uplink: 2. 6 kb/sec (max) SDO System Concept Review HMI - Scherrer 40
Spacecraft Resource Drivers HMI Stanford University Advanced Technology Center • Data Continuity & Completeness – Capture 99. 99% of the HMI data (during 90 sec observing periods) – Capture data 95% of all observing time • Spacecraft Pointing & Stability – The spacecraft shall maintain the HMI reference boresight to within 200 arcsec of sun center – The spacecraft shall maintain the HMI roll reference to within TBD arcsec of solar North – The spacecraft shall maintain drift of the spacecraft reference boresight relative to the HMI reference boresight to within 14 arcsec in the Y and Z axes over a period not less than one week. – The spacecraft jitter at the HMI mounting interface to the optical bench shall be less than 5 arcsec (3 sigma) over frequencies of 0. 02 Hz to 50 Hz in the X, Y and Z axes. • Reference Time – Spacecraft on-board time shall be accurate to 100 ms with respect to ground time (goal of 10 ms) SDO System Concept Review HMI - Scherrer 41
HMI Heritage HMI Stanford University Advanced Technology Center • • The primary HMI heritage is the Michelson Doppler Imager instrument which has been successfully operating in space for over 7 years. Between launch in December 1995 and March 2003, almost 70 million exposures have been taken by MDI. Most of the HMI sub-systems are based on designs developed for MDI and subsequent space instruments developed at LMSAL. – Lyot filter has heritage from Spacelab-2/SOUP, SOHO/MDI, Solar-B/FPP instruments. – HMI Michelson interferometers will be very similar to the MDI Michelsons. – Hollow core motors, filterwheel mechanisms, shutters and their controllers have been used in SOHO/MDI, TRACE, SXI, Epic/Triana, Solar-B/FPP, Solar-B/XRT, Stereo/SECCHI. – The Image Stabilization System is very similar to the MDI design, and aspects of the ISS have been used in TRACE and Stereo/SECCHI. – The main control processor planned for HMI is being used on the SXI and Solar-B/FPP instruments. SDO System Concept Review HMI - Scherrer 42
HMI Design Heritage HMI Stanford University Advanced Technology Center The HMI design is based on the successful Michelson Doppler Imager instrument. SDO System Concept Review HMI - Scherrer 43
HMI Mechanisms Heritage HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 44
HMI Technology Readiness Level HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 45
HMI Assembly & Integration Flow Stanford University Advanced Technology Center Entrance filter Calibrate filter Integrate & align telescope Telescope structure Optics fabrication Operations & Analysis Fabricate optical elements Verify optics performance Fabricate Optics Package Launch & commissioning Lyot element fabrication Assemble/align Lyot cells Michelsons fabrication Calibrate Michelsons Assemble/cal. Lyot filter Verify optics performance Spacecraft I&T Assemble/test filter oven system Assemble & align on optical bench Assemble & align in optics package Oven & controller fabrication Test oven & controller Fabricate mechanisms Test mechanisms Fabricate focal plane Integrate focal plane Calibrate focal plane Test & calibrate ISS Integrate electronics, software, & OP CCD detector Camera electronics Fabricate ISS Fabricate electronics SDO System Concept Review HMI calibration HMI environmental test HMI functional test Develop Software HMI - Scherrer 46
Environmental Test Approach HMI Stanford University Advanced Technology Center • • In general environmental test will be done at the integrated HMI level to protoflight levels & durations The preferred order of testing is: – – – – LFFT SPT for Calibration SPT for Sunlight Performance EMI/EMC LFFT Sine & Random Vibration › Electronics & Optics Package separately › Powered off LFFT Thermal Vacuum / Thermal Balance LFFT SPT for Calibration SPT for Sunlight Performance in vacuum Mass Properties Delivery SDO System Concept Review HMI - Scherrer 47
Instrument Calibration Approach HMI Stanford University Advanced Technology Center • Critical subsystems will be calibrated at LMSAL prior to integration these include – – – • • The CCD cameras The Michelsons The Lyot filter Mechanisms Other optical elements The completed HMI will be calibrated at LMSAL using lasers, the stimulus telescope and the Sun The completed HMI will be calibrated at LMSAL in vacuum using both the stimulus telescope and the Sun SDO System Concept Review HMI - Scherrer 48
Functional Test Approach HMI Stanford University Advanced Technology Center • • • HMI will use a structured test approach so that the test at each point in the program can be appropriate to the need and consistent test results can be obtained The tests will be controlled by STOL procedures running in the EGSE and will use released test procedures The Aliveness test will run in less than 30 minutes and will do a quick test of the major subsystems The Short Form Functional Test (SFFT) will run in a few hours and will test all subsystems but will not test all modes or paths. It will not require the stimulus telescope The Long Form Functional Test (LFFT) will run in about 8 hours and will attempt to cover all paths and major modes. The SFFT is a subset of the LFFT. The LFFT will require the use of the stimulus telescope Special Performance Tests (SPT) are tests that measure a specific aspect of the HMI performance. These are detailed test that require the stimulus telescope or other special setups. They are used only a few times in the program SDO System Concept Review HMI - Scherrer 49
HMI Functional Test on Observatory HMI Stanford University Advanced Technology Center • • SFFT / LFFT / SPT are derived from Instrument level tests We assume that GSFC will provide an interface to the HMI EGSE so the same EGSE system can be used to test HMI after integration onto the spacecraft We will use the HMI stimulus telescope to verify HMI calibration while HMI is mounted on the spacecraft We recommend the inclusion of a spacecraft level jitter compatibility test SDO System Concept Review HMI - Scherrer 50
Schedule and Critical Path HMI Stanford University Advanced Technology Center SDO System Concept Review HMI - Scherrer 51
Risks Assessment – Instrument Development HMI Stanford University Advanced Technology Center • Filter performance: – The Lyot filter and Michelson interferometers are the heart of the HMI instrument. Although we have previously built these filters for the MDI instrument, there are relatively few vendors with the specialized skills necessary for their fabrication. We are working aggressively to develop detailed filter specifications and identify potential vendors. • Mechanisms longevity : – Although the hollow core motor and shutter planned for HMI have significant flight heritage, the required number of mechanism moves is of concern. Lifetests of the hollow core motors and shutters are planned to validate their performance for the planned SDO mission duration. • Thermal performance: – The thermal stability of the HMI instrument is critical to achieving it’s ultimate performance. Detailed thermal modeling and subsystem thermal testing will be used to optimize thermal design. SDO System Concept Review HMI - Scherrer 52
HMI Risks Assessment - Programmatic Stanford University Advanced Technology Center • HMI camera electronics has potential schedule/cost impact: – Obtaining SECHHI derived camera electronics from the Rutherford Appleton Laboratory in the UK is a viable option for HMI, but the development schedule is not know in detail. If this option is chosen, we feel it is best that we obtain the camera electronics directly from RAL. – A modified Solar-B/FPP camera electronics developed by LMSAL will also meet the HMI requirements. This option has less schedule risk, but costs and camera power and mass are higher than the RAL camera. • Timely negotiation of HMI Product Assurance Implementation Plan SDO System Concept Review HMI - Scherrer 53
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