TIPS-JIM Meeting
18 March 2004, 10am, Auditorium
1.
Modeling of Optical Ghosts in WFC3
Olivia Lupie
2.
Time Dependent Sensitivity for STIS
David Stys
3.
The MIRI delta-SRR
Margaret Meixner
Next TIPS Meeting will be held on 15 April 2004.
WFC3 Filter Testing, Modeling, Designing
TEAM
Ghosts (spurious reflections) in some UVIS filters were discovered during
first ambient calibration of WFC3
Ambient Cal Filter Ghost Characterization – T. Brown, O. Lupie
GSFC Lab Setup (spare and proto-type filters): Randy Telfer (Orbital, GSFC),
Ray Boucarut (GSFC)
Filter Modeling: Dave Kubalak, Randy Telfer, (Orbital), Bill Eichhorn (GSFC)
GSFC Lab Data Reduction , Analysis: Sylvia Baggett, Olivia Lupie
Vendors: Barr Associates, Omega Optical
UVIS Ambient Nano Calibration – G. Hartig, N. Reid, S. Baggett, T. Brown,
H. Bushouse, B. Hilbert, O. Lupie
March 18, 2004
Tips – Olivia Lupie
1
Parameters Used to Spec a Filter to Vendors
Parameters Used to Spec a Filter
Pre-Install Test
Spectral Requirements
x
x
x
x
x
x
Wavelength tolerances
Central wavelength
Slopes of bandpass sides/wings
Out of Band Rejection Longward of Passband
Out of Band Rejection Shortward of Passband
Ripples in Passband
Scattered Light
x
x
x
x
Angle of Incidence
Focus shift and Filter thickness
Anti Reflection Coatings
Operational Temperature
Dimensions
x
x
x
mechanical size, shape
Clear Aperture size
Wedge - for transmitted wavefront - substrates
Optical Figure
Surface quality
Transmitted Wavefront
Scratch-Dig-blemishes
Adhesion of coating
Hardness of coating
Humidity
x
Vendor uses specs to design a filter:
•Determine substrates, coatings, coating
thicknesses, deposition process.
•Provide model of throughput, out of band
rejection, spatial uniformity
•Model is accepted or rejected
•Vendor builds the filter
x
x
x
x
x
Construction
Adhesive bondline
Coating materials - general
Adhesives
Edge Sealants
Environmental Requirements
not usually tested before install 18,costly,
2004 schedule prohibitive
instrumentMarch
specific,
x
x
x
x
x
Tips – Olivia Lupie
2
WFC3 Filter Testing, Modeling, Designing
WFPC-1’s SOFA – 12 wheels
• Converging instantaneous beam footprint
• F31 beam
• +/- 3 degree range for field angles
Filter Wheel Filter Wheel Filter Wheel
1
6
12
UVIS CCD
.
10 mm
57.3
mm
14 mm
~3o
.
.
Edge Rays Define
Field-Of-View
March 18, 2004
Tips – Olivia Lupie
Instantaneous Beam
Footprint
Image Rays
Image
3
F225 Transmission Theoretical vs Measured
1.1
1
0.9
0.8
Transmission
0.7
0.6
0.5
sht1
0.4
desired bandshape
0.3
0.2
0.1
0
150
200
250
300
1.1
350
400
450
500
550
600
Wavelength (nm)
1
0.9
0.8
Transmission
0.7
sht1
0.6
sht2
0.5
desired bandshape
0.4
0.3
0.2
0.1
0
150
200
250
300
350
400
450
500
550
600
Wavelength (nm)
1.1
1
0.9
0.8
"Transmission"
0.7
sht1
0.6
sht2
0.5
AR Coating
0.4
met block
0.3
desired bandshape
0.2
Theoretical Transmission
0.1
0
150
200
March 18, 2004
250
300
350
400
Tips
– Olivia Lupie
Wavelength
(nm)
450
500
550
4
600
Spectral Shaping of the Filter
1.1
1
0.9
0.8
"Transmission"
0.7
sht1
0.6
sht2
0.5
AR Coating
0.4
met block
0.3
desired bandshape
0.2
Theoretical Transmission
0.1
0
150
200
250
300
350
400
450
500
550
600
Wavelength (nm)
1.1
Theoretical Reflectivity
1.0
0.9
0.8
Reflectivity
0.7
0.6
sht1 refl
0.5
sht2 refl
0.4
AR Coat
met block refl
0.3
0.2
0.1
0.0
150
200
March 18, 2004
250
300
350
400
Wavelength (nm)
Tips – Olivia Lupie
450
500
550
600
5
Modeling Status
Air-Gap
Construction
Possible Model of F225W Ghosting (modelers: Randy Telfer, Dave Kubalak)
Aberrations result from reflections from metal blocker
Anti-reflection
Substrate #1
Metal blocker
(aberrations –
astigmatism)
1
Substrate 1.1 mm
2
Bond &
GAP (0.38 mm)
Spacer
3
Shortpass 1
Substrate 3.0 mm
Substrate #2
4
Shortpass 2
Ideally – all surfaces
perfectly parallel
2nd order ghosts
doubly aberrated
1st order ghosts
Transmitted
aberrated
Airgap replaced adhesive – adhesive reduced throughput and introduce
major spatial dependence across filter
March 18, 2004
Tips – Olivia Lupie
6
Flight Filter Ghosts
(worst cases)
Some wide band UV air-gap filters exhibited large amplitude ghost images:
> 10% in white light
> 10% in white light
F218W
F225W
F218W
F225W
<1% in white light
F300X
<1% in white light
F606X
March 18, 2004
Tips – Olivia Lupie
(analysis T. Brown with ICAL team)
7
Lab Measurements of Spare F606
Flight – F606W in WFC3
White light – 5 micron fiber
Faint point
0.02%
ghosts at
0.3%
~0.1% of the
0.06%
primary image
0.08%
test artifact intensity, moving
0.08%
little with field
0.13
position.
%
Larger donut
ghosts at 0.3%,
moving
significantly.
March 18, 2004
Faint point
ghosts at
~0.01% of the
primary image
Intensity. Field
angle check in
work..
*white light
ghosts 10x
fainter than
Flight –
however more
testing is
needed to
verify.
Tips – Olivia Lupie
Spare – F606W – lab
Cohu, 10 micron fiber
Xenon Lamp
8
F225W
Primary images
ghosts
200 nm
275 nm
Low level
ghosts
400 nm
1100 nm
From Nano-Cal :
First Order Ghost Strength as a Percentage of Primary Image F225W
80%
70%
F rom M o d e ls :
60%
st ro ng gho st
su rfaces 4 3
-
st ro ng gho st
su rfaces 3 2
-
st ro ng gho st
su rfaces 4 2
-
Transmission
50%
40%
R a t oi : M e a su red
g h o s t ful x /p rmi e ful x
M e a su red
F i tl e r T h ro u g h p u t
30%
20%
10%
0%
March 18, 2004
180
200
220
240
260
280
300
320
340
360
380
Tips – Olivia Lupie
Wavelength (nm)
400
420
440
460
480
500
9
Spectral Modeling of Ghosts (D. Kubalak)
First Order Ghost Strength as a Percentage of Primary Image F225W
80%
70%
Surfaces (3-2)
Note - Surface (4-2)
curve overlaps with
extended wing of in band
transmission
Surfaces (4-3)
Surfaces (4-2)
Surfaces (4-1)
60%
meas ghost ratio
meas trans
Surface (3-1)
Transmission
50%
Surface (2-1)
Model Transmission after two reflections. To
compare models to measured ratio of ghost strength to in-band
transmission (black curve with open circles), scale surface
curves by transmission (wfc3 + filter + ota + stimulus) at the
wavelength. Models do not yet produce as high
a ghost transmission ecause of complexities but they
indicate which surfaces are most responsible.
40%
30%
20%
F225
10%
0%
180 200 220
240 260
280 300 320
340 360 380
400 420
440 460 480
500 520 540
560 580
600
Wavelength (nm)
Ghost spectral modeling- D. Kubalak
March 18, 2004
Tips – Olivia Lupie
10
Phase Retrieval and Spectral Ghost Models
Flight Filter
Strange Morphology combination of Astigmatism,
overall curvature, local surface
ripples
Phase Retrieval from Focus Sweeps
(R. Telfer)
March 18, 2004
Tips – Olivia Lupie
11
Air-Gap Ghost Mechanisms
Two-surface reflection modeling indicates the metal blocker is the likely origin of the ghost
behavior. Vendors also say that the metal coating is the least “controllable”.
The observed wavelength dependence is understood. Red and Blue near-band wings are not as steep
as desired. This excess light occurs at the wavelengths where ghosts could be produced by the airgap construction. Model ghost fluxes (10-12%) are comparable to measured in white light.
Phase Retrieval reveals ghost images are astigmatic for 218W and 225W, that the coatings are tilted
w/r to one another, and filter has a slow, slight curvature possibly consistent with a
shrinkage/distortion at the spacer/metal blocker interface.
None of these issues have any effect on the transmitted beam and throughput – both were excellent.
March 18, 2004
Tips – Olivia Lupie
12
Status Filter-Ghost
Mitigation Plan
1.
PLAN
Adopt a 3-option approach for Air-Gaps:
STATUS
Barr to proto-type new F218, 225, (and 300X) filters
– single substrate
Barr sent thin prototype single substrate – testing
in the GSFC – only one ghost present, white
light 0.6%
IPT tested image quality using special lab setup – flight
Spare filters to see if they exhibit less ghosting.
F218 and F225 spares same problem.
F606 spare exhibits similar type ghosts but
greatly reduced ghost amplitude (~0.03%)
IPT is investigating a wedge fix – original design but
with increased wedge to deflect reflected light;
IPT is investigating dual-wheel air gap – achieved
wedge by stacked-SOFA wheel approach;
requires two coated substrates and loss of a filter(s).
2. Mechanism for F606w (laminated) ghosts
is being discussed with OMEGA.
March 18, 2004
Modeling shows you cannot tilt filter enough
and still stay with bounds of the filter housing..
By “tilting” the spare air-gap, we can determine
how much relative tilt of the two substrates
is needed to move the ghosts out of the fov.
Data taken last night.
OMEGA is devising a new design.
Tips – Olivia Lupie
13
GSFC Lab Testing Facility
Optics Team: R. Telfer, R. Boucarut, D. Kubalak, B. Eichhorn, J. Kirk, B. Greeley
Science IPT: O. Lupie, S. Baggett, B. Hilbert, T. Brown, G. Hartig
Goals – last few weeks: 1) Prove that the GSFC Lab Test setup accurately
simulates the WFC3, i.e., measurements are true representations of the filter
imaging quality, and 2) Measure the flight spares.
•UV Sensitive CCD.
Off-axisParabola
•Cover Structure for
uniform/dark background.
Fiber
F/31Beam
Filter
CCD
•Automated Castle and
CCD data take system.
Castle Cart
Double
Mono
chrometer
March 18, 2004
•Mechanical stage mount
for filters.
presents F31 light beam
to the filters as they would
see in the WFC3+OTA
Tips – Olivia Lupie
•Semi-Automated data
reduction and analysis.
14
Lab Measurements of Spare F225W
SPARE F225
Cohu Video CCD,
200 micron fiber
FLIGHT F225
5 micron fiber,
WFC3
(sum ghosts=15%)
Saturated
prime
Saturated
prime
10%
10%
SPARE F225
SBIG CCD,10 micron fiber,
9%
0.5%
2%
UV00
0.5%
Saturated
prime
UV00
UV14
UV14
Note – rotation and stretch
are different.
March 18, 2004
Tips – Olivia Lupie
Relative positions and fluxes
of ghosts in the spares are
comparable to those in the
flight similar mechanisms.
15
Example Monochromatic Results for
Spare F225W
Spare F225, SBIG-CCD, 200 micron fiber, 13nm bandpass, double UVIS, ,
with ND1 (removed in later imaging).
220nm
240nm
260nm
300 nm
320 nm
340 nm
280nm
Figure from S.Baggett
March 18, 2004
Tips – Olivia Lupie
16
Establish Setup Sensitivity and Repeatability
Spare F225W
Ran many tests to
establish sensitivity to
ghosts, setup alignment
accuracy, and
experimented with
several different filter
orientations: rotation,
back to front, tilts,
translation, wedge
orientation and detector
tilts.
nominal
-1d
-2d
+1d
+2d
Xenon Lamp, 10 mic Fiber
Rotate Filter a few degrees from nominal and compare
Ghost morphology
March 18, 2004
Tips – Olivia Lupie
17
Establish Setup Sensitivity and Repeatability
Also Helps modelers to see all the ghosts
saturated unsaturated
Primary, Secondary
ghosts emerge from
behind the primary and
each other when large
translations or rotations of
the filter are introduced:
ie different locations on
filter and differing field
angles.
center
saturated unsaturated
center - shows repeatability
+0.5 in
+1.0 in
-0.5 in
-1.0 in
Xenon Lamp, 10 mic Fiber
v. Large tilt –
30 deg to corner
Translating the filter
Figure from S.Baggett
March 18, 2004
Tips – Olivia Lupie
18
Prototype F225 – Single Substrate
Setup artifact
Prototype thickness is
smaller than that of a flight
filter. Thicker filters result
in ghosts at a larger radial
distance from the primary.
But tilting the thin filter,
we can see when the ghost
emerges and use a simple
Model to derive the ghost
position with a thicker
filter.
nominal
-3d
-9d
-12d
-6d
Ghost 0.6%
-15d
Prototype Single Substrate – large tilts
(Xenon Lamp, 10 micron fiber, CCD SBIG)
Figure from S.Baggett
March 18, 2004
Tips – Olivia Lupie
19
8.0E-01
trial
7.0E-01
th trans
th refl
6.0E-01
flight 225-302 trans
orig theor
5.0E-01
Transmission
Proto
Type
F225
From
Barr
"Feb_19 Trial F225W"
4.0E-01
3.0E-01
2.0E-01
1.0E-01
0.0E+00
190
200
210
220
230
240
250
260
270
280
290
300
"Wavelength"
7.0E-05
Feb_19 Trial F225W" - OOB Blocking
trial
6.0E-05
theoretical trans
meas 225-302 OOB
Transmission
5.0E-05
4.0E-05
3.0E-05
2.0E-05
1.0E-05
0.0E+00
March 18, 2004
200
300
400
500
600
700
Tips – Olivia Lupie
"Wavelength"
800
900
1000
1100
20
Prototype F225 – Single Substrate
Setup artifact
Ghosts as a function of
wavelength
200nm
250nm
300nm
400nm
450nm
500nm
600nm
650nm
700nm
750nm
800nm
850nm
900nm
900nm
350nm
Setup
SBIG CCD, 200 mic fiber
Castle Modes
<250nm double UV
250-310 double UVIS
310-760 double VIS
>760 double IR
March 18, 2004
225nm
Ghost#1
Ghost#2
Tips – Olivia Lupie
Figure from S.Baggett
21
• 53 of 63 filters exhibit excellent performance, consistent with spec.
•
•
47 filters < 0.2% ghosts
6 filters 0.2-0.5% ghosts
- multi-substrate - 410M, 689M, 814M
- air-gap – 656N, 665N, 673N
• 2 filters 0.7% ghosts:
•
single substrate+Al blocker - 275W can calibrate
•
air-gap - 658N
• 2 UV high priority air-gap (with Aluminum blocker) 10-15% ghosts - 218W, 225W unsuitable for
flight
• 1 UV air-gap 1% with strange morphology - 300X marginal, tough to calibrate
• 1 3-substr laminated, < 0.5% “point-like” ghosts - 606W most used filter, concern
(other filters with very low level “point ghosts”: 625W, 775W, 410M, 467M, 547M, 621M, 689M)
• 1 UV single subst.+Al block, possible surface flaw – 280N serious but low priority filter
• 2 UV Quad filters single substrate, 5% ghosts:– 232N, 243N low priority filters, can calibrate
• Grism – data reduction in work
March 18, 2004
Tips – Olivia Lupie
23
Time Dependent Sensitivity
STIS CCD-Modes
Currently
Ralph Bohlin
Scott Friedman (PI)
Paul Barrett
Previously
Nolan Walborn
Ed Smith
Ivo Busko
STYS - TIPS ‘04
TDS: Time Dependent Sensitivity
• Monitor the sensitivity of each CCD grating mode
to detect any changes due to contamination or
other causes.
• Prior to analysis we first account for temperature
dependencies as well as losses due to CTE.
• Create reference files for use in the STIS datareduction pipeline to correct extracted 1D spectra
for time dependent sensitivity losses.
Observations
Cycle Proposal
7
7672
8
8418
9
8856
10
8914
11
9627
12
10030
•
AGK+81D266 is a flux standard sub-dwarf
whose position allows for observations
throughout the year.
•
CRSPLIT = 2 for cosmic ray rejection;
CCDGAIN=1 (default)
•
G750L and G750M observations have
contemporaneous fringe flat exposures for
fringe removal.
Frequency
Every two
months
Every three
months
1.5 months
G230LB
• 1700-3000 angstroms
• 173 sec. exposure
• 34 observations
Net Count Rate
AGK+81D266
Wavelength (A)
G430L
• 2900-5700 angstroms
• 173 sec. exposure
• 35 observations
Net Count Rate
AGK+81D266
Wavelength (A)
G750L
• 5500-9900 angstroms
• 432 sec. exposure
• 35 observations
Net Count Rate
AGK+81D266
Wavelength (A)
Temperature Dependency
Mode
%/C
G230LB
0.34
G430L
0.25
G750L
0.07
The Problem
Net Count Rate
G230LB
Wavelength (A)
t0 ~ 1997
t1 ~ 2004
The Ratio
Obsn/Reference
t1/t0
0.91
Wavelength (A)
t0 ~ 1997
t1 ~ 2004
Avg. G230LB Trends
Sensitivity loss
1%/yr - 3%/yr
1.10%/yr +/- 0.19 sig = 0.23%
-1.79%/yr +/- 0.10 sig = 0.59%
-0.43%/yr +/- 0.43 sig=0.59%
G230LB - all wavelengths
Avg. G430L Trends
Sensitivity loss
0.2%/yr
Avg. G750L Trends
Sensitivity loss
Typically 0%/yr
Pipeline Implementation
G230LB
t0 ~ 1997
t1 ~ 2004
Flux
mean(ratio)
0.995
• A TDS reference file contains MJDs and slopes at
each wavelength bin.
• calSTIS uses linear interpolation to correct each
observation based on wavelength and epoch.
• The result is an extracted 1D flux spectrum
corrected for both TDS and CTE.
G230LB
Uncorrected Net Count Rate
Corrected FLUX
Side 2
Electronics
1.10%/yr +/- 0.19 sig = 0.23%
-1.79%/yr +/- 0.10 sig = 0.59%
-0.43%/yr +/- 0.43 sig=0.59%
G430L
Uncorrected Net Count Rate
Corrected FLUX
G750L
Uncorrected Net Count Rate
Corrected FLUX
Summary
• STIS sensitivity has been monitored since activation and is
dependent on time, temperature and wavelength.
• Sensitivity losses in the CCD modes range from 0%/yr
(G750L) to ~3%/yr (G230LB)
• M-mode sensitivities mimic the trends found in the Lmodes. We apply the L-mode corrections to the M-modes
since we only observe medium dispersion modes at
selected wavelengths.
• TDS reference files are available for first-order MAMA
and CCD modes. In the future, imaging and echelle modes
will also be corrected for TDS.
Mid-InfraRed Instrument (MIRI)
Delta-Systems Requirements
Review: March 9
Margaret Meixner
MIRI support scientist
Result of MIRI delta-SRR
MIRI project successfully completed the delta System Requirements Review.
The review board was very complementary of the extensive preparation of the
requirements documentation and the systematic documentation of the flow
down of the requirements. The hard work of the entire MIRI Team was
acknowledged and commended.
MIRI Delta Systems Requirements Review 9 March 2004
2
MIRI has four Science Modes
1. Photometric Imaging
3. Coronagraphy
2. Low Resolution Spectroscopy
MIRI Delta Systems Requirements Review 9 March 2004
3
MIRI has four Science Modes
4. Integral Field Unit Spectroscopy
MIRI Delta Systems Requirements Review 9 March 2004
4
MIRI in the System
REGION 1
REGION 2
REGION 3
(37 K)
(75-300 K)
(300 K)
T
V
T
Dewar I/Fs
Under review
Routine Monitoring
Discretes / Passive Analog
T
T
Launch-Critical
Discretes /Passive Analog
DCE
RS-422 / 1553B
(TBD)
S
S/C
CTP
MIRI
FSW
(TBD)
Thermal Straps
MIRI Dewar
SpaceWire
(6.65 K @ FPM Strap I/F
6.85K @ OBA Strap I/F)
FPE
1553B
Thermal Switch
T Temperature Transducer
V Valve Actuator
S
ICE
IC&DH
MIRI
FSW
MIRI OBA
(7 K)
MIRI Delta Systems Requirements Review 9 March 2004
5
System Requirement Review
Held on Nov 4 and 5, 2003 at JPL
First Instrument SRR on JWST. The higher level flow downs were not
complete
Was held before ISIM and Observatory SRRs
Board requested delta SRR to address issues raised in the board report
Received 97 RFAs
MIRI Delta Systems Requirements Review 9 March 2004
6
After MIRI SRR
45 RFAs were reassigned internally
NIRCam successfully completed their SRR
MIRI prepared plan for addressing the Board comments
Observatory Successfully completed their SRR
ISIM SRR scheduled for March 16
MIRI delta SRR scheduled for March 9
Established the content and the format for delta SRR in consultation with
the review board
Delta SRR package distributed on Feb 24
MIRI Delta Systems Requirements Review 9 March 2004
7
Review Board Report Summary – Part I
The working relationships between the MIRI principals, JPL and ESA,
appear to be excellent
The science requirements in particular appear to be clearly understood
The MIRI team provided a clear depiction of open issues affecting the
instrument system.
It was observed that the MIRI team, which is spread over the globe with
multiple centers and institutional participants, is obviously fully operational
and is filled with an enthusiastic spirit.
The MIRI team has a clear definition of the instrument design at this early
stage of the project.
The MIRI project has an excellent, very capable team.
There appears to be an excellent understanding and flowdown of the
science requirements. There was clearly a thorough
knowledge of the source of the science requirements and how the
requirements flowdown to the subsystems.
MIRI Delta Systems Requirements Review 9 March 2004
8
Board Report Summary – Part II
Group a) 1,3,4,5,9 and 11
1.
The flow down from the SciRD to the instrument system and subsystem
architecture was spotty
3
Few presenters discussed the derived, flow down of the requirements,
instead they presented designs that reflected their approach to meeting
the assumed requirements.
4
Consistency of the OBA design approach with the requirements was
not made clear to the Board.
5
Uncertainties plague the definition of the requirements. The JWST
project made changes in its requirements documentation, the System
IRD, which was not available to the MIRI team in time to be incorporated
in the material presented at the MIRI SRR. This situation impacted the
ability of the MIRI Team to convince the Board that it had a clear grasp
of the requirements and the impact of the requirements on the system
design.
MIRI Delta Systems Requirements Review 9 March 2004
9
Observatory Requirements
JWST Program Plan
JWST-PLAN-000633 L1
Program
System
JWST Science
Requirements Document
JWST-RQMT-002558SR
JWST Mission
Requirements
JWST-RQMT-000634 MR
JWST Performance
Assurance Requirements
JWST-RQMT-000650 PA
JWST Mission Operations
Concept Document
JWST-OPS-002018 MOC
FGS OCD
Budgets
WFE Rev Q 03-JWST-0405
Efficiency
Pointing
WFS&C Requirements
Allocation Document
JWST-RQMT-002017 WFS
NIRCam OCD
EMC Control Plan
JWST-PLAN-002449
Performance Quality
Assurance Plan
JWST-PLAN-002412
NIRSpec OCD
EMC
Contamination Control
Plan
JWST-PLAN-002028
CCP
PQ
MIRI OCD
Segment
Flight Observatory to
Ground Segment IRD
JWST-IRD-000696 FG
Ground Segment
Requirements
JWST-RQMT-001056
GS
JWST Observatory
Specification
JWST-SPEC-002020
RD
JWST System
Verification Plan
JWST-PLAN-002027
OL
OBS
JWST-ICD-001998 FGC
Radiation Requirements
Allocation Specification
JWST-SPEC-000871
Observatory to Launch
Segment IRD
JWST-IRD-002000
JWST-ICD-002001
OLC
Environmental Req’s
for the JWST Observatory
JWST-SPEC-003149
Observatory I&T Plan
JWST-PLAN-002030
EV
Observatory to
GSE IRD
D36127 OG
D36128 OGC
Fault Protection
Requirements Document
JWST-RQMT-002450
FP
Element
ISIM Requirements
Document
JWST-RQMT-000835
ISIM
ISIM to OTE and
Spacecraft IRD
JWST-IRD-000640
ISIM to OTE and IOS-IR
JWST-ICD-001831
SC Requirements Document
JWST-RQMT-002039
SC
Spacecraft to OTE
ICD
D35231 SOIC
OTE Specification
JWST-RQMT-002021
OTE
IOSC
MIRI Delta Systems Requirements Review 9 March 2004
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ISIM Requirements
JWST Observatory
Specification
JWST-SPEC-002020
OBS
Segment
Fault Protection
Requirements Document
JWST-RQMT-002450
FP
Element
Mission Assurance Requirements
For the JWST Instruments
JWST-RQMT-002363
ISIM Requirements
Document
JWST-RQMT-000835
MAR
ISIM
ESA JWST Product Assurance
Requirements Document
ESA-JWST-RQ-64
ISIM to OTE and
Spacecraft IRD
JWST-IRD-000640
ISIM to OTE and IOS-IR
JWST-ICD-001831
IOSC
PAR
CSA Performance Assurance
Requirements CSA-TBD
NIRCam IRD
JWST-IRD-000780
ISIM to OTE and INCU
JWST-ICD-000728
INCC
NIRSpec IRD
JWST-IRD-000781
ISIM to OTE and INSU
JWST-ICD-000729
MIRI IRD
JWST-IRD-000782
ISIM to OTE and IMU
INSC
JWST-ICD-000730
IMC
FGS IRD
JWST-IRD-000783
ISIM to OTE and
JWST-ICD-000727
IF
IFC
Subsystem
NIRCam Functional
Requirements Document
JWST-SPEC-002049
NRC
NIRSpec Functional
Requirements Document
JWST-SPEC-002060
MIRI Functional
Requirements Document
JWST-SPEC-002063
NRS
ISIM Structure Requirements
JWST-RQMT-002087
IST
MIR
ISIM Flight
Software Requirements
JWST-RQMT-002101
FGS Instrument Performance
and Functional Requirements
JWST-SPEC-002069
FGS
ICDH Requirements
JWST-RQMT-000743
IFSW
MIRI Delta Systems Requirements Review 9 March 2004
ICDH
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JWST Requirements Flow Down to MIRI
Element
S/C Requirements
JWST-RQMT-002039
SC
S/C FSW
Xxxx-xxx-xxxxxx
ISIM to OTE and
Spacecraft IRD
JWST-IRD-000640
ISIM to OTE and IOS-IR
ISIM Requirements
JWST-RQMT-000835
ISIM
Mission Assurance Requirements
For the JWST Instruments
JWST-RQMT-002363
MAR
ISIM FSW
JWST-RQMT-002101
IFSW
JWST-ICD-001831 IOSC
Subsystem
ESA JWST
Product Assurance
Requirements Document
ESA-JWST-RQ-64
PAR
MIRI Functional
Requirements Document
(JWST-SPEC-002063)
JPL D-24158
MIR
MIRI IRD
JWST-IRD-000782
IMU
MIRI Mission
Assurance Plan
JPL D-25631
MAP
MIRI System Requirements
(JPL) D-25646
SYS
Component
MIRI OBA Requirements
EC MIRI-RS-00001
OBA
MIRI Dewar Requirements
JPL D-25641 DWR
MIRI FSW Requirements
JPL D-24160
MFSW
MIRI Delta Systems Requirements Review 9 March 2004
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JWST Requirements Trace to MIRI FRD
Rationale
{OBS-552} The science instruments and FGS
guider channels minimum unvignetted field of
views in the OTE focal plane shall be equal
to, or greater than the values shown in the
table below. Table 3-15. Field of View
Science Instrument FOV (arc-minutes) MIRI
2.4 x 2.4
Minimum unvignetted field of view for imaging and
spectroscopy.
ISIM-235 Field of View
The science instruments and FGS guider
channels minimum unvignetted field of views in
the OTE focal plane shall be equal to, or greater
than the values shown in the table below.
MIRI is 3.5 square arc-minutes. (1.87 x 1.87
arc-min)
Allocation
MIRI Allocation
ISIM-520
MIRI Field of View
The minimum effective science field of
view for the MIRI modules is 3.5 (TBR)
sq arc min. (1.87 x 1.87 arc-min)
MIRI FRD
MIRI Delta Systems Requirements Review 9 March 2004
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Critical Issues List
Sensitivity
Pupil shear
Focus tolerance
Image quality - WFE/FWHM
Contamination
Dewar mass
Target acquisition
Observing efficiency
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Dewar Mass
Requirement: The MIRI Cryo Dewar shall have a mass allocation of 208 kg,
including cryogen, dewar mounting structure and margins. (RS-4.4-SYS0003)
Issue: The estimated mass of a Dewar that meets the Dewar performance
requirements is greater than the allocation (228kg versus the 208kg
allocation).
5 year Operational lifetime after cool down and commissioning (FRD 3.5.2)
Instrument heat lift of 60mW (RS-4.5-SYS-0005)
MIRI Delta Systems Requirements Review 9 March 2004
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Dewar Mass Requirement Trace
{OBS-637} ISIM Mass
ISIM-322
Rationale
ISIM set the total mass allocation for MIRI for each region
of the ISIM in the MIRI-ISIM IRD
ISIM Mass
The mass of the ISIM shall not exceed 1,630
kilograms (TBR).
The MIRI Requirements Document allocated the Region
1 mass of MIRI. 103kg were allocated to the OBA and
208kg to the Dewar.
Balance of the dewar mass is kept as system margin in
the MIRI System Requirements Document (RS-4.4-SYS0001)
MIRI
Allocation
IMU-817 Region 1 Component Allocations
The MIRI Region 1 Assembly shall have a
mass less than 311 kg, excluding external
harnesses.
Component
Allocation
SysRD RS-4.4-SYS- 0003 Dewar Mass
Dewar RS-DWR-4.2-0012
The MIRI Cryo Dewar shall have a mass
allocation of 208 kg, including cryogen, dewar
mounting structure and margins.
Mass: The total mass of the dewar including
its supports to the ISIM at launch, including
the margins as specified below shall not
exceed 197.6kg.
MIRI Delta Systems Requirements Review 9 March 2004
Mass
16
Options
Current baseline estimate is 228kg.
Detailed trade studies have shown opportunity
for 10-15kg mass reduction
1.
Heat redistribution from FPM strap to OA
strap
2.
Warmer OA interface temperature
3.
OBA cooled by ISIM to 40K
4.
On pad liquid helium cooling available
5.
Warmer end of life detector temperature
6.
Combine options 1 and 3
7.
Combine options 1 and 4
8.
Combine options 1 and 5
9.
Combine options 1, 3 and 4
10.
Combine options 1, 3, and 5
single option
combination of options
240
230
Mass (kg)
220
210
200
190
0
2
4
6
8
10
Option
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Status
Dewar RFP ready for release(March 2004)
Will get Dewar vendor on board by May
Options and trades will be settled once we have Dewar vendor on board to validate the
mass estimates and options.
Based on vendor assessment we will revisit the Mass availability from ISIM
.
Trades:
Heat redistribution from FPM strap to OM strap
• Has been accepted as new baseline.
Warmer OA interface temperature
• Will be assessed, based on vendor response.
OBA cooled by ISIM to 40K
• Under review with ISIM ICD team
On pad liquid helium cooling available
• Visit to Ariane Space in April
Warmer end of life detector temperature
• 0.2K increase to the detector operating temperature has been accepted.
Combine cases
• Can combine cases 1 and 5 (14kg net savings)
• Additional cases will be combined if net system savings found. Decision by May
MIRI Delta Systems Requirements Review 9 March 2004
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Target Acquisition Status
High Level requirements to support target acquisition will be worked out
by MIRI PDR.
The target acquisition software will be written by the ISIM FSW group to
requirements specified by the MIRI science team.
A working group is being established by the Project to work the details
of target acquisition requirements with all instrument teams represented.
Ray Kutina (STScI) will lead the working group. Meetings will start by
the end of March.
Algorithms for centroiding will also be worked out by this group.
The IC&DH software implementation of target acquisition is scheduled
for fall of ‘05, so there is some time to work out the IC&DH details.
MIRI Delta Systems Requirements Review 9 March 2004
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Requirement Traceability for Observing Efficiency
{OBS-629} ISIM Efficiency
Rationale
ISIM 524
MIRI Efficiency
After commissioning, the ratio of prime exposure
time on scientific targets to total elapsed time, for
the MIRI instrument, shall be greater than 95%
(TBR) over a 5-year mission.
MIRI Operations Concept Document, section 6, outlines
a Month in the Life of MIRI, which is a very top level, very
approximate operational scenario to estimate the time for
MIRI operations. This operational scenario assumes a
heavy weight on long exposures. We derived a 92%
efficiency, however, given the uncertainty in operational
scenario, we add margin and list a 89% efficiency for
MIRI.
Telescope slews and similar operations are not counted
against the MIRI operational efficiency
MIRI Allocation
FRD 3.4.1
Setup, Cleanup and Mode
Switching
The MIRI operational efficiency
shall be greater than 89 (TBR)%….
FRD 3.4.3
Detector Annealing Efficiency
…specification within 2 hours
(TBR) of the end of a detector
annealing procedure.
FRD 2.4.2.3
Spectral Calibration Stability
Wavelength calibration shall be
required no more often than once
per week …
FRD 3.3.9
Instrument Turn-on Time
… obtain science data within 30
minutes of turn on.
MIRI Delta Systems Requirements Review 9 March 2004
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Observing Efficiency Status
The observing efficiency budget has been recognized as a project wide
open issue and will be re-evaluated based on meetings of the
observing efficiency working group led by Lionel Mitchell (GSFC).
Mitchell led a technical interface meeting on Friday, Feb. 27 to discuss
observing efficiency with a project wide working group, including
representatives from the project, OTE, space craft, ISIM, instrument
teams and SOC. This meeting was an information exchange in which
the instrument teams discussed the assumptions made for observing
efficiency estimates.
The efficiency requirements are being re-cast in terms of overheads for
the ISIM and SI subsystems. Due March 15, MIRI is working on an
overhead time request for its operations.
This work, which began last October with the OTE and S/C will be
continued with incorporation of an operational scenario based on a
design reference mission (DRM) that is being developed at STScI with
expectation of completion in the summer.
The observing efficiency working group is looking at operations
assumptions and not instrument design.
MIRI Delta Systems Requirements Review 9 March 2004
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RFA Categories
Legend for Categories for all 97 ( including withdrawn):
1- Flow down from level 1 to FRD/IRD (ISIM lead),
include critical issues
23
2 - Flow down to MIRI subsystems (MIRI lead)
5
3 - Software programmability
2
4 - In process tasks (design advisory)
7
5 - Mass management
5
6 - Sensitivity models
2
7 – Advisory and/or to be completed by PDR
25
8 – clarification
12
9 - Various/specific
4
MIRI Delta Systems Requirements Review 9 March 2004
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Summary
JWST has completed requirements flow down to MIRI Instrument
MIRI requirements documents are in place
Project has excellent flow down and tracking process
All of the critical issues are being addressed; many have been closed out.
Most of the RFAs have been addressed. The remaining will be tracked to
MIRI PDR.
MIRI Delta Systems Requirements Review 9 March 2004
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