The Integrated Science Instrument Module
Ground Test
Matt Greenhouse
ISIM Project Scientist
NASA Goddard Space Flight Center
23 July 2010
ISIM is the science instrument payload of the JWST
 ISIM is one of three elements that together make up the JWST space vehicle
– Approximately 1.4 metric tons, ~20% of JWST by mass or cost
 The ISIM system consists of:
– Four science instruments
– Nine instrument support systems:
- Optical metering structure system
- Electrical Harness System
- Harness Radiator System
- ISIM electronics compartment (IEC)
- ISIM Remote Services Unit (IRSU)
- Cryogenic Thermal Control System
- ISIM Command and Data Handling System
(ICDH)
- Flight Software System
- Operations Scripts System
23 July 2010
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The ISIM system completed CDR during March 2009
 All science instrument ETU test programs have been completed
– All instrument ETUs have been delivered
 Flight model integration is underway on all instruments and supporting systems
NIRSpec Development Model
FGS Engineering Model
23 July 2010
NIRCam Engineering Test Unit
MIRI Verification Model
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Making sure it all works ….
 Science instruments and each of their 9 supporting systems are individually
flight qualified prior to delivery to ISIM I&T
 Ground testing at the ISIM element level is designed to (no order):
–
–
–
–
–
–
–
–
–
–
Verify instrument alignment with the ISIM structure
Verify instrument compatibility with the: harness system, ICDH, IRSU, FSW, & OSS
Verify design performance wrt EMI/EMC
Verify instrument compatibility with the FGS
Verify SI-to-SI compatibility for parallel mode dark calibration
Characterize thermal performance for model validation
Characterize ISIM performance stability for model validation
Correlate instrument performance in ISIM to instrument-level test results
Verify workmanship for flight environment
Measure mass properties
 Approximately 200 requirements to be verified at ISIM assembly level
 ISIM is subsequently delivered to observatory-level I&T as a flight qualified
element
23 July 2010
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ISIM is one of three element-level test programs
ISIM I&T
I&T Responsibility
OTE/ISIM
I&T
Execution
GSFC SSDIF
OTE
Structure
I&T
GSFC SSDIF, JSC 32
Pathfinder
Optics
Integration
NG M8
N/A
GSFC SSDIF
NG M8
OTE
Pathfinder
Structure
NGST
ITT
ESA /
Arianespace
Cryo
Optics
Test
OTE
I&T
Facility
NASA
Pathfinder
Cryo Optics
Test
GSFC SSDIF
JSC 32
Propulsion
Module I&T
Observatory
EM Test Bed
(EMTB)
NG M3
Spacecraft
Panel I&T
NG M8
Sunshield
Pathfinders
(EPF/IVA)
NG M8
23 July 2010
Sunshield I&T
NG M8
Spacecraft
Element I&T
Complete
Observatory
I&T
NG M8, LATF, M4 Vibe
Launch
Site I&T
LV
Integ
Launch
NG R8
CSG S5C, S5B, BAF, ZL3
NG M8, M4 TV
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The ISIM element test article (sans ICHD)
Use or disclosure of data contained on this page is subject to the restriction(s) on the title page of this document.
6
ISIM Test Verification Flow
INS-20xxx
TST-20900
Receive Flight ISIM Electronics
Compartment Structure with
Backbone Harness
IEC Sine &
Random
Vibe Test
FLT IEC
Integration
(FLT E-box)
TST-20600
Alignment
Metrology
Deintegrate
For Vib and
Mass Props
System
Functional
Test
IEC Mass
Properties
dI
TST-20700
INS-20xxx
Receive Flight
ISIM Structure
TST-21000
TST-20910
TST-21000
ISIM Gravity
Release Test
ISIM Mass
Properties
rI
Integrate:
HAS,CHA, HR,
Harness, SIs
TST-20400
Cryo Thermal Vacuum Test
w/TMS and OSIM
TST-21200
Cryo Thermal Vacuum Test
w/TMS and OSIM
TST-20800
EMI/EMC
Test
Acoustics Test
(ISIM & IEC)
TST-21300
INS-21301
Clean, Inspect,
Pack & Ship
TST-20900
TST-21100
dI
Sine Vibe Test
(ISIM Only)
rI
TST-30000
OTE Integration
& Test Program
OTE Cryo Vac
At JSC
rI – Re-Integrate ISIM and IEC
dI – De-Integrate ISIM and IEC
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ISIM will be tested at ~35 K in the GSFC SES chamber
using a cryogenic telescope simulator (OSIM)
SES chamber
(27 x 40 ft)
LHe shroud installation and
test completed July 09
LN2 Shroud
LHe shroud
ISIM
OSIM
Vibration
Isolation
Supports
Fold Mirror 3 Tip/Tilt
Gimbal Assembly
Alignment Diagnostic Module
23 July 2010
OSIM Primary Mirror
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Major ground support equipment required for ISIM I&T
 Primary ground support equipment:
– Cryogenic Optical Telescope Simulator (OSIM)
- Simulates Optical Telescope Element (OTE) with high fidelity
– OSIM Beam Analyzer
– Space environment simulator LHe shroud
- Enables ISIM testing at operating temperature
– Cryogenic photogrammetry system
- Enables metrology of ISIM structure at operating temperature
– ISIM Test Platform (ITP)
- Simulates OTE mechanical interface at cryogenic operating temperature
 ISIM simulators provided to support SI-Level testing:
– Ambient science instrument mechanical interface fixture (ASMIF)
- Simulates ISIM structure mechanical interface for each instrument with high fidelity
– Science instrument test sets (SITS)
- Simulates ICDH for each instrument
23 July 2010
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The ISIM structure has passed key verification tests for
cryogenic dimensional reputability and distortion
 Carbon-fiber/cyanate-ester composite material
– Primary launch-load bearing structure (warm launch)
– High precision optical requirements
 Key dimensional requirements for thermal cycling (300
to 30 K) verified to > 25 micron precision
– Repeatability: 80 microns
– Distortion: 500 microns
 Key tests to-go:
– Cryogenic and ambient strength proof tests
– Modal survey
23 July 2010
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Key Thermal Performance Test Objectives
• Best-controlled opportunity for ISIM thermal testing
– 460 mW total power allocation to cryogenic portion of ISIM
– Very sensitive to workmanship
• Thermal test objectives:
– Thermal model correlation and validation
– Workmanship/performance of critical thermal elements (heat straps,
harnesses, MLI, contamination control heaters/algorithms, trim
heaters, temp sensors
– SI stability during multi-instrument operation
– Sensitivity of ISIM to backplane interface temperature
– MIRI thermal performance, heat load measurement within heat shield
– IEC thermal balance, thermal cycling, transient stability, steady state
surface and electronics box temperatures
23 July 2010
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ISIM enclosure and passive cryogenic radiators replaced by
precision controlled cryo-pannels
 Flight radiators integrated at OTIS assembly level
 Q meters used to verify thermal loads and flight heat strap performance
 MIRI cooling provided by GSE cryo-cooler compressor
Flight high purity aluminum heat strap assemblies
23 July 2010
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IEC and Harness Radiator Flight Configuration
23 July 2010
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The ISIM electronics compartment successfully addresses
one of most difficult engineering challenges of the JWST
 The IEC accommodates 11 warm electronics boxes that must reside on the
cryogenic side of the sunshield close to the science instruments
 Rejects ~220 W of power to space in a controlled beam pattern to achieve
required observatory thermal balance and avoid thermal stray light
– Radiator beam pattern verified in prototype test
 Key test to-go: full thermal balance
Flight Shell
23 July 2010
Flight Baffle
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IEC & HR test shrouds simulate flight cryogenic
environment with high fidelity
~ 25 K Test Shroud
IEC
HR (~ 20 - 25 K) Shroud
lined with black honeycomb
HR with flight harnesses
23 July 2010
15
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Flight cryogenic radiators are replaced by a surrogate thermal
management system
LN2 Shroud
GHe Shroud
IEC Two Shroud Assembly
LN2 shroud surrounded by
dedicated He shroud
plumbed to the primary chamber
He shroud.
Harness Radiator with –V1
Shroud
Optical Telescope
Element Simulator (OSIM)
23 July 2010
Vibration Isolation
System
Surrogate Thermal
Management System (STMS)
• Comprised of actively
controlled panels to produce
environment of flight TMS to
ISIM (Region 1)
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Approximately 150 optical requirements are verified or
cross checked during ISIM element testing
• Only opportunity for testing integrated instrument suite with flightlike beam of flight-like image quality/wavefront
• Comprehensive optical performance test plan confirms alignment,
image quality, wavefront sensing capability
OPRG1
• Basic optical capabilities
OPRG2
• Wavefront and focus requirements
• Calibration requirements for the MIMF
wavefront sensing algorithm
OPRG3
• Pupil shear and rotation requirements
23 July 2010
OPRG4
• Fields of view, vignetting, stray light
• Absolute pointing of ISIM
OPRG5
• Co-boresight stability vs temperture
OPRG6
• Performance of NIRCam wavefront
sensing and control components
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Science Instrument (SI) sensitivity verification
 SI-level requirements cover every filter and mode of
the instrument
– Verified at instrument level as part of their qualification
ahead of delivery to ISIM I&T
- Component-level testing combined with models
 Sensitivity models held under configuration control
 Spec values used for OTE parameters
 Sensitivity benchmarks will be measured on SI
internal sources during ISIM-element testing for
correlation with SI-level test results
– POM contamination monitored with witness plates and
NIRSpec spectroscopy on OSIM continuum sources
23 July 2010
JWST-RQMT-835: ISIM-153
JWST Sensitivity: SN=10 in < 10,000s
Instrument
l (mm)
l/Dl
Continuum
Flux Density
(nJy)
Unresolved
Line Flux
(10-21Wm-2)
NIRCam
2
4
11
FGS-TF
3.5
100
126
NIRSpec
3
100
132
NIRSpec
2
1000
MIRI
10
5
700
MIRI
21
4.2
8700
MIRI
9.2
2400
10
MIRI
22.5
1200
560
0.52*
* SN = 10 in < 100,000 s
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Each of two cryogenic test cycles require ~20 weeks
with ~ 6 weeks used for cool-down and warm-up
23 July 2010
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Learn more at: www.jwst.nasa.gov
Watch the ISIM being built at:
www.jwst.nasa.gov/webcam.html
Read about JWST science mission objectives at:
http://www.jwst.nasa.gov/science.html
Collaborate on JWST science investigations:
http://www.stsci.edu/institute/conference/jwst2011
23 July 2010
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23 July 2010
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ISIM Instrument characteristics wallet card
ISIM Fast Facts
Key Instrument Characteristics (as of Mar 06)
Instrument
NIRCam
Channel/Mode
Shortwave
Longwave
Wavelength
(microns)
Typical Spectral
Resolution (l/Dl)
0.6 - 2.3
2.4 - 5.0
1.0 - 5.0
4,10,100
4,10,100
1000
0.6 - 5.0
100
Long Slits (5)
1.0 - 5.0
100, 1000, 2700
IFU
Imager
Low Res Slit
0.7 - 5.0
5 - 27
5 - 11
4.87 - 7.76
7.45 - 11.87
11.47 - 18.24
17.54 - 28.82
1.6 - 2.5, 3.2 - 4.9
0.8 - 5.0
2700
4-6
100
3000
3000
3000
2250
100
0.7
Multi-Object Spec
NIRSpec
MIRI
Med Res IFU
FGS-TF
FGS-Guider
Angular
Resolution
(arc sec)
0.032 / pixel
0.065 / pixel
FOV
2.2' x 2.2' each of 2 modules
2.2' x 2.2' each of 2 modules
203 x 463 mas clear shutter aperture, 267 x
528 mas pitch, 4 x 171 x 365 shutter array
format, 9.7 sq arcmin mulit-object targetable
solid angle
200 x 3500 mas x 3, 400 x 4000 mas,
100 x 2000 mas
3 x 3 arc-sec
1.9' x 1.4'
5" x 0.6"
3.7" x 3.7"
4.7" x 4.5"
6.2" x 6.1"
7.1" x 7.7"
2.2' x 2.2'
2.3' x 2.3' each of 2 modules
Number of
Sensor Chip
Arrays
8
2
Mega Pixels
Detector
Temp (K)
34
8
Detector Type / Format
NIR=18 um pixels
MIR=25 um pixels
HgCdTe / 2048 x 2048
HgCdTe / 2048 x 2048
2
8
HgCdTe / 2048 x 2048
37
1
1
1
1
Si:As / 1024 x 1024
Si:As / 1024 x 1024
7
7
1
1
Si:As / 1024 x 1024
7
1
2
Total ISIM
4
8
66
HgCdTe / 2048 x 2048
HgCdTe / 2048 x 2048
40
40
40
40
see FOV
0.10 slice width
0.11 / pixel
see FOV
0.18 slice width
0.28 slice width
0.39 slice width
0.65 slice width
0.065 / pixel
0.068 / pixel
JWST Sensitivity (JWST-RQMT-000634 Rev-M Baseline)
Wavelength Instrument/Mode
(microns)
2
3.5
3
2
10
21
NIRCam
FGS-TF
NIRSpec/Low Res
NIRSpec/ Med Res
MIRI/ Broadband
MIRI/Broadband
23 July 2010
Bandwidth
(l/Dl)
SNR
Maximum Wall Clock Time (s)
4
100
100
NA
5
4.2
10
10
10
10
10
10
10,000
10,000
10,000
100,000
10,000
10,000
Continuum
Continuum
Unresolved
Flux Density
Flux Density
Line Flux
-33
-2
-1
(nJy)
(10 W m Hz ) (10-21 W m-2)
11.40
126.00
132.00
NA
700.00
8700.00
0.11
1.26
1.32
NA
7.00
87.00
NA
NA
NA
0.57
NA
NA
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NIRCam will provide the deepest near-infrared images ever and will
identify primeval galaxy targets for the NIRSpec
Pick-off Mirror
Subassembly
Coronagraph
Elements
Longwave Filter
Wheel Assembly
Elements
Longwave Triplet
Subassembly
Longwave Focal
Plane Housing Fold
Mirror
Shortwave Focal
Plane Housing Fold
Mirror
First Fold Mirror
Subassembly
Collimator Triplet
Subassembly
Dichroic
Beamsplitter
Shortwave Filter
Wheel Assembly
Elements
Shortwave Triplet
Subassembly
Shortwave Fold
Mirror
Pupil Imaging Lens
 Developed by the University of Arizona with Lockheed Martin ATC
–
–
–
–
–
–
Operating wavelength: 0.6 – 5.0 microns
Spectral resolution: 4, 10, 100
Field of view: 2.2 x 4.4 arc minutes
Angular resolution (1 pixel): 32 mas < 2.3 microns, 65 mas > 2.4 microns
Detector type: HgCdTe, 2048 x 2048 pixel format, 10 detectors, 40 K passive cooling
Refractive optics, Beryllium structure
 Supports OTE wavefront sensing
23 July 2010
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The NIRSpec will aquire spectra of up to 100 galaxies in
a single exposure
Prism/Grating
Wheel
Filter
Wheel
Telescope Focus
(f/20)
Pick-off Mirror(s)
Foreoptics
MIcro-shutter
Array
(f/12.5)
Collimator
Camera
Detector
Array
(f/5.67)
 Developed by the European Space Technology Center
(ESTEC) with Astrium GmbH and Goddard Space Flight Ctr
– Operating wavelength: 0.6 – 5.0 microns
– Spectral resolution: 100, 1000, 3000
– Field of view: 3.4 x 3.4 arc minutes
- Aperture control: programmable micro-shutters, 250,000
pixels
- Angular resolution: shutter open area 203 x 463 mas, pitch 267 x
528 mas
– Detector type: HgCdTe, 2048 x 2048 pixel format, 2 detectors,
37 K passive cooling
– Reflective optics, SiC structure and optics
23 July 2010
Fixed Slits
and
IFU Aperture
3.4’
Detector Array
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3.6’
24
Aperture control: 250, 000 programmable micro-shutters
System at TRL-8 and delivered to ESA June 2010
203 x 463 mas shutter pixel clear aperture, 267 x 528 mas pitch, 4 x 171 x 365 array
Human Hair 90 um Dia.
23 July 2010
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The MIRI instrument will detect key discriminators that distinguish
the earliest state of galaxy evolution from more evolved objects
Optical Assembly Structural/Thermal Model
 Developed by a European Consortium and JPL
– Operating wavelength: 5 - 29 microns
– Spectral resolution: 5, 100, 2000
– Field of view: 1.9 x 1.4 arc minutes broad-band imagery
- R100 spectroscopy 5 x 0.2 arc sec slit
- R2000 spectroscopy 3.5 x 3.5 and 7 x 7 arc sec integral field units
– Detector type: Si:As, 1024 x 1024 pixel format, 3 detectors, 7 K cryo-cooler
– Reflective optics, Aluminum structure and optics
23 July 2010
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The FGS provides imagery for telescope pointing control & imaging
spectroscopy to reveal primeval galaxies and extra-solar planets
 Developed by the Canadian Space Agency with ComDev
– Operating wavelength: 0.8 – 4.8 microns
– Spectral resolution: Broad-band guider and R=100 science imagery
– Field of view: 2.3 x 2.3 arc minutes
- R=100 imagery with Fabry-Perot tunable filter and coronagraph
– Angular resolution (1 pixel): 68 mas
– Detector type: HgCdTe, 2048 x 2048 pixel format, 3 detectors
– Reflective optics, Aluminum structure and optics
23 July 2010
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