Transcript 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,

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
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HMI
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
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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
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HMI Science Objectives
HMI
Stanford University
Advanced Technology Center
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Convection-zone dynamics and the solar dynamo
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Origin and evolution of sunspots, active regions and complexes of activity
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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
Links between the internal processes and dynamics of the corona and heliosphere
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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
Sources and drivers of solar activity and disturbances
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Structure and dynamics of the tachocline
Variations in differential rotation
Evolution of meridional circulation
Dynamics in the near surface shear layer
Complexity and energetics of the solar corona
Large-scale coronal field estimates
Coronal magnetic structure and solar wind
Precursors of solar disturbances for space-weather forecasts
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Far-side imaging and activity index
Predicting emergence of active regions by helioseismic imaging
Determination of magnetic cloud Bs events
SDO System Concept Review
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HMI Science Data Products
HMI
Stanford University
Advanced Technology Center
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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.
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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 (0-30Mm)
Carrington synoptic v and cs maps (0-30Mm)
High-resolution v and cs maps (0-30Mm)
Deep-focus v and cs maps (0-200Mm)
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
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HMI
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 (0-30Mm)
Near-Surface Shear Layer
Carrington synoptic v and cs
maps (0-30Mm)
Active Regions
Activity Complexes
Sunspots
Observables
High-resolution v and cs
maps (0-30Mm)
Doppler
Velocity
Deep-focus v and cs
maps (0-200Mm)
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 1.0w
HMI - Scherrer
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HMI Observables Requirements
HMI
Stanford University
Advanced Technology Center
SDO System Concept Review
HMI - Scherrer
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HMI Observables Requirements
HMI
Stanford University
Advanced Technology Center
SDO System Concept Review
HMI - Scherrer
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HMI Observables Requirements
HMI
Stanford University
Advanced Technology Center
SDO System Concept Review
HMI - Scherrer
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HMI
Source of Requirements
Stanford University
Advanced Technology Center
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HMI Investigation
HMI Science Objectives
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Duration of mission
Completeness of coverage
HMI Science Data Products
Roll accuracy
Time accuracy (months)
HMI Observations
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Duration of sequence
Cadence
Completeness (95% of data sequence)
Noise
Resolution
Time accuracy (days)
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HMI Observables
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Sensitivity
Linearity
Acceptable measurement noise
Image stability
Time rate (minutes)
Completeness (99.9% of observable data in
90s)
Orbit knowledge
SDO System Concept Review
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HMI Instrument Data
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Accuracy
Noise levels
Completeness (99.99% of data in filtergram)
Tuning & shutter repeatability
Wavelength knowledge
Image registration
Image orientation jitter
HMI Instrument Concept
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Mass
Power
Telemetry
Envelope
Sub-system requirements
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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
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Key Requirements
HMI
Stanford University
Advanced Technology Center
SDO System Concept Review
HMI - Scherrer
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HMI Instrument Concept
HMI
Stanford University
Advanced Technology Center
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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
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HMI Optical Layout
HMI
Stanford University
Advanced Technology Center
SDO System Concept Review
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HMI Optics Package Layout
HMI
Stanford University
Advanced Technology Center
SDO System Concept Review
HMI - Scherrer
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HMI Design Improves on MDI
HMI
Stanford University
Advanced Technology Center
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The HMI common design features based on MDI:
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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:
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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 4096x4096 pixels instead of 1024x1024 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
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HMI
HMI Subsystems
Stanford University
Advanced Technology Center
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Optics Package Structure
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Optics Subsystem
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Includes all the optical elements except the filters
Filter subsystem
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The filter subsystem includes all the filters and Michelsons
Provides the ability to select the wavelenght to image
Thermal Subsystem
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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
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Consists of active mirror, limb sensor, precision digital & analog control electronics
It actively stabilizes the image reducing the effects of jitter
Mechanisms Subsystem
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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
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The CCD camera subsystem includes 4Kx4K CCDs and the camera electronics box(es)
HMI Electronics Subsystem
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Provides conditioned power and control for all HMI subsystems as well as HMI C&DH hardware
Software Subsystem
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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
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HMI
HMI Functional Block Diagram
Stanford University
Advanced Technology Center
PWB
Buffer
memory
Buffer
Memory
(2
x 4K x 4K x 16)
(2x4Kx4Kx16)
PWB
Camera data
Mechanism
&&
Mechanism
heater
controllers
Heater
Controllers
PWB
Data
compressor
Data
Compressor /
& Buffer
AEC
Camera Electronics Box
PWB
Buffer
memory
Spacecraft
Interface
ISS
ISS
(Limb
tracker)
(Limb
tracker)
Image Stabilization System
Limb Sensor & Active Mirror
ISS data
PWB
Control
PC/local
PC/local
bus bridge/
Bus Bridge
EEPROM
PWB
ISS
ISS
(PZT
drivers)
(PZT
drivers)
PWB
PWB
Housekeeping
data acquisition
Data
Acquisition
Central
Processor/
Central
processor
EEPROM
Optics Package
PCI
Bus
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
Spacecraft
SDOSDO
Spacecraft
DC DC
- DC
power
- DC
Power
converter
Converter
Camera
Camera
interface
Interface
(SMClite) )
( SMClite
Control
Housekeeping
ADC,
Housekeeping
ADC,
& Master
Clock
& master
clock
LVDS
LVDS
Control
CCD
IEEE 1355
Control
CCD Driver Card (2)
Clock & sequencer
CDS/ADC
Command / Data Interface
CCD
PWB
Power
Power
converters
Converters
Electronics Box
SDO System Concept Review
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Optics Subsystem
HMI
Stanford University
Advanced Technology Center
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1 arc-sec diffraction limited image at the sensor
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Solar disk at the sensor 4.9 cm
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Requires 14 cm aperture
Requires 4096x4096 pixel sensor
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
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HMI
Filter subsystem
Stanford University
Advanced Technology Center
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Central wavelength 6173Å Fe I line
Reject 99% of solar heat load from the OP interior
Total bandwidth 76mÅ FWHM
Tunable range 500 mÅ
Very high stability and repeatability required (to be quantified)
The required bandwidth obtained by cascading filters as follows
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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
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Narrowest Lyot element
Wide Michelson
Narrow Michelson
SDO System Concept Review
HMI - Scherrer
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MDI Lyot Elements and Michelson Interferometers
HMI
Stanford University
Advanced Technology Center
SDO System Concept Review
HMI - Scherrer
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HMI
Thermal Subsystem
Stanford University
Advanced Technology Center
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Optics package thermal control
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Filter oven
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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
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Operating temperature range 15 to 25 °C
Active control to ±0.5 °C
Control loop in software
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
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Minimize radial gradients
Return to normal operating temperature within 60 minutes of eclipse exit
SDO System Concept Review
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Image Stabilization Subsystem
HMI
Stanford University
Advanced Technology Center
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Stability (over TBC second period) 0.1 arc-sec
Range ± 14 arc-sec
Frequency range 0 to 50Hz
Continuous operation for life of mission
SDO System Concept Review
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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
40M exposures
Hollow core motors
• Move time (60 deg)
• Repeatability
• Accuracy
• Life (5 year)
<800 ms
60 arc-sec
10 arc-min
80M moves
SDO System Concept Review
HMI - Scherrer
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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
XX arc-min
20K 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
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CCD Camera Subsystem
HMI
Stanford University
Advanced Technology Center
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Format
Pixel size
Full well
Readout noise
Readout time
Digitization
Dark current
SDO System Concept Review
4096 x 4096 pixels
12 um
>125K electrons
40 electrons
<3.4 seconds
12 bits
10 –e/sec/pixel at –60 °C
HMI - Scherrer
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HMI
HMI Electronics Subsystem
Stanford University
Advanced Technology Center
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Provide conditioned power and control for all HMI subsystems
Provide processor for:
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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
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Commands
Housekeeping telemetry
Diagnostic telemetry
SDO System Concept Review
2.5 kbps
2.5 kbps
10 kbps (when requested)
HMI - Scherrer
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HMI Operations Concept
HMI
Stanford University
Advanced Technology Center
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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
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HMI Dataflow Concept
HMI
Stanford University
Advanced Technology Center
} Pipeline
SDO System Concept Review
HMI - Scherrer
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HMI
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 (0-30Mm)
Carrington synoptic v and cs
maps (0-30Mm)
High-resolution v and cs
maps (0-30Mm)
Deep-focus v and cs
maps (0-200Mm)
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 1.2w
HMI - Scherrer
29
HMI
Completed Trade Studies
Stanford University
Advanced Technology Center
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Observing Wavelength
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CPU
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RAD 6000 vs. RAD 750 vs. Coldfire: RAD 6000 selected (from SXI)
High-Rate Telemetry Board
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6173 Å vs. 6768 Å: 6173 Å selected
Single Board or to include a redundant board: Redundant concept selected
Sensor Trade
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CMOS vs. CCD Detector: CCD selected
SDO System Concept Review
HMI - Scherrer
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HMI
Trade Studies In Progress
Stanford University
Advanced Technology Center
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Inclusion of redundant mechanisms in HMI Optic Package
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Inclusion of redundant power supply in HMI Electronics Box
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Increased reliability versus Increased cost and mass
Just started this trade
Camera Subsystem - evaluating two options
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Increased reliability vs. Increased cost & mass
Have allocated volume to not preclude additional mechanisms
Build in-house an evolution of a Solar-B FPP Camera
Procure from RAL an evolution of a SECCHI Camera
CCD Configuration
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Evaluating operation in front side or back side illuminated mode
SDO System Concept Review
HMI - Scherrer
31
HMI
HMI CCD and Camera Electronics
Stanford University
Advanced Technology Center
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Baseline CCD vendor is E2V
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Specification drafted - includes capabilities that allow more optimal camera electronics
design and requires less power
SHARP and HMI to use identical CCDs
E2V to be given a design phase contract ASAP
Two principal paths for development of camera electronics
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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
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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
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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
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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 – 3D 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
HMI Electronics Box Layout
Stanford University
Advanced Technology Center
SPARE
7.7 in
CAMERA INTERFACE/BUFFER
CAMERA INTERFACE/BUFFER
Current Layout
Envelope
(20 Mar 2003)
COMPRESSOR/HIGH RATE INTERFACE A
COMPRESSOR/HIGH RATE INTERFACE B
14.2 in
PZT DRIVERS
MECHANISM & HEATER CONTROLLERS
9.5 in
LIMB TRACKER
X = 361 mm
Y = 241 mm
Z = 234 mm
MECHANISM & HEATER CONTROLLERS
MECHANISM & HEATER CONTROLLERS
PCI/LOCAL BUS BRIDGE/1553 Interface
HOUSEKEEPING DATA ACQUISITION
RAD 6000/EEPROM
Internal cabling for I/O connectors
requires 3“ in one dimension
X
Power supply adds 1.1 in in one dimension
9.2 in
Y
End View
Z
Z
Top View
SDO System Concept Review
HMI - Scherrer
35
HMI Resources – Mass Estimates
HMI
Stanford University
Advanced Technology Center
•
Mass – no margin included
20 Mar 2003
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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
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35.3 kg (TBC)
15.0 kg (TBC)
3.0 kg (TBC)
OP Assumptions
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Optics Package (OP, w/LMSAL-CEB):
HMI Electronics Box (HEB):
Harness:
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
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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
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OP
20 Mar 2003
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Ixx:
1.00 kg-m2 (TBC)
Iyy:
4.30 kg-m2 (TBC)
Izz:
3.48 kg-m2 (TBC)
these estimates are about the CG along OP axes so are therefore NOT principal axes, i.e.
there are also some small inertia products
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CG (x,y,z) = 487 mm, 145 mm, 21 mm (TBC)
HEB
20 Mar 2003
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Ixx:
0.79 kg-m2 (TBC)
Iyy:
0.22 kg-m2 (TBC)
Izz:
0.97 kg-m2 (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
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CG (x,y,z) = 180 mm, 110 mm, 98 mm (TBC)
SDO System Concept Review
HMI - Scherrer
37
HMI
HMI Resources - Average Power
Stanford University
Advanced Technology Center
20 Mar 2003
EB Electronics
OP Oven Control
OP Filter Oven
subtotal
PC Inefficiency
subtotal
Survival Heaters
CCD Decontam Heaters
Operational Heaters (4)
subtotal
CEB (LMSAL)
Margin
TOTAL
Operational
Mode (1)
30.5
1
3
34.5
14.8
49.3
0
0
13
62.3
30
15
107.3
W
W
W
W
W
W
W
W
W
W
W
Eclipse
Mode (2)
30.5
1
3
34.5
14.8
49.3
0
0
23
72.3
30
15
117.3
Survival
Mode
W
W
W
W
W
W
W
W
W
W
W
0
0
0
0
0
0
45
0
0
45
0
9
54
W
W
W
W
Early Ops
(3)
0
0
0
0
0
0
45
22
0
67
0
9
76
W
W
W
W
W
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
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HMI Resources – Mass Estimates
HMI
Stanford University
Advanced Technology Center
•
Mass – no margin included
20 Mar 2003
–
–
–
•
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
–
–
–
–
•
35.3 kg (TBC)
15.0 kg (TBC)
3.0 kg (TBC)
OP Assumptions
–
–
–
•
Optics Package (OP, w/LMSAL-CEB):
HMI Electronics Box (HEB):
Harness:
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
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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
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Spacecraft Resource Drivers
HMI
Stanford University
Advanced Technology Center
•
Data Continuity & Completeness
–
–
•
Spacecraft Pointing & Stability
–
–
–
–
•
Capture 99.99% of the HMI data (during 90 sec observing periods)
Capture data 95% of all observing time
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
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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
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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
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
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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
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HMI - Scherrer
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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:
–
•
Mechanisms longevity :
–
•
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.
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 the 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
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