WFC3 TIPS
John W. MacKenty
TIPS Presentation 29 November 2007
1
What a Difference a Year Makes!
•
This time last year:
– SOFA was delivered to GSFC after filter ghosts and chips fixed
• New IR Grisms were just installed
– Circuit boards were all removed and retested
• Still troubleshooting a MEB1 failure to start issue
– IR2 (substrate on) was still the only complete IR detector
• IR1 was just completing bypass surgery for a failed internal JFET
– TV2 was scheduled to start 3/28/07 (Launch May 08)
– Most of the new IR Detector Lot 4 wafers at Teledyne had failed
• One part on a backup wafer (FPA150) would become IR3
– Randy & I were trying to “sell” a Lot 4C IR detector run Æ FPA165
•
We did not see coming:
–
–
–
–
Electrical short in UVIS1
Damage to TECs in UVIS1 and UVIS2
Thermal control problems with IR 6-stage TEC
Failure of 3 (of 4) Tungsten bulbs in the internal calibration system
John W. MacKenty
TIPS Presentation 29 November 2007
2
WFC3 Status Today
•
•
•
•
•
The WFC3 team persevered through the successful 127 day T/V-2 campaign
(with three chamber breaks) that verified most of the instrument’s performance.
Completed first round of EMI/EMC testing (only one minor issue)
Complete fit checks into HFMS and Crew Fam
IR4 (Flight) and IR3 (Spare) Detectors at GSFC [IR4 about to be installed!]
UVIS1’ (Flight) detector
–
–
–
–
–
•
TEC replaced
Flex leads coated with insulator after multiple metal particles found
Glint discovered in TV2 fix within installed of baffle inside UVIS1’ package
UVIS1’ partway through thermal cycling (and was vibed yesterday at Ball)
Schedule to arrive at GSFC next week for immediate installation
The replacement Tungsten Lamp assemblies for the Calibration Sub-System are
assembled and aligned for drop-in replacement at GSFC.
– Presently in test at Ball
•
•
TV3 is schedule for 42 days starting early February 2008
Final WFC3 Delivery to HST I&T is holding at 3/30/08.
John W. MacKenty
TIPS Presentation 29 November 2007
3
WFC3 Schedule
8/08 Shuttle Launch
3/24 – 3/25/07
UVIS2 Detector
Installation
10/24/05 – 4/5/07
4/5/07 – 8/12/07
Instrument
Integration
Pre-IR
Detector
Instrument
Level Testing
(Includes T/V
test-2)
8/29/07– 9/17/07
T/V– 2B
IR FPA Temp &
Throughput
Investigation
9/20/07– 10/13/07
T/V– 2D
IR FPA Temp
Control
Verification
5/23/06 – 5/16/07
10/15/07
Build Flight IR1
Detector Assy
10/28 – 12/6/07
Delivery to
HST I&T
10/1/06 – 8/27/07
Build Flight IR3
Det. Assembly
12/3/07
10/1/06 – 11/07
Prime and
Spare Detector
Designation
Build Flight IR4
Det. Assembly
11/27 – 12/15/07
Flight detector
installation(s)
and final
instrument
closeout
3/2/07 – 12/07
UVIS1 Detector
Reassembly and
Test
4/1/07 – 2/29/08
Build Flight
UVIS3 Det.
Assembly
John W. MacKenty
Cal Subsystem
& LVPS Rework
12/26 – 1/4/08
= NEW
Acoustic -2
1/4 – 1/25/08
EMI / EMC -2
1/30/08 – 03/24/08
T/V test -3
NET 3/3/08 – 3/14/08
UVIS3
Installation?
TIPS Presentation 29 November 2007
= CRITICAL
PATH ITEM
12/21/07 – 3/27/08
T/V test -3
(Dedicated SES
chamber time)
3/30/08
Final
Delivery to
HST I&T
4
WFC3 in SES
(prior to installation of thermal shrouds)
John W. MacKenty
TIPS Presentation 29 November 2007
5
TV2 Summary
• Statistics
– 127 days in SES Chamber with 93 days of 24/7 operations
– Over 15,000 images from >350 SMS runs
– 25 STScI scientists and data analysts supported this effort
• Validated many issues from prior testing
–
–
–
–
–
–
–
–
Electronics and detector heatpipes worked well
Detector crosstalk fixed in both channels
UVIS optical filter ghosts resolved and SOFA working well
Internal flat field illumination uniformity much improved
IR grisms properly aligned (and IR backgrounds correct)
Detector alignment transfers worked very well
CCD charge injection working properly
Line-of-sight stability looks much better (but still 2x specification)
John W. MacKenty
TIPS Presentation 29 November 2007
6
TV2 Issues
•
IR FPA temperature control
– Spacecraft voltage variations due to orbital cycling produce FPA
temperature fluctuations – detector has non-linear dark
– Was ~1 degC in TV1; Initial fix for TV2 resulted in 1.7 degC
– Led to decision to perform TV2-B,C,D with LVPS board mods
– Significant coupling issues discovered and resolved
– Current performance of 0.15 degC demonstrated (expect to improve)
•
Calibration Subsystem:
– Tungsten lamps 2 & 4 failed early in TV2 (lamp3 declining by end)
• New bulbs from alternate vendor procured – in test and looking good
– D2 lamp turn-on delays (within tolerable range)
•
Significant glint discovered in UVIS detector package
– Repaired in UVIS1
•
IR throughput degradation/variation
– Now believed to be an issue with ground calibration equipment!!
John W. MacKenty
TIPS Presentation 29 November 2007
7
UVIS Glint
• Large area effected with up to 20% of energy
into a 10,000 pixel glint feature
• Present by design in both UVIS1&2
• Cause of flat field “flare” feature
• Fixed by addition of mask behind outer
window (UVIS vacuum enclosure)
• UVIS2 (deep spare) not fixed
John W. MacKenty
TIPS Presentation 29 November 2007
8
Image Stability: Hot Case
orbital slew
orbital cycling
orbital cycling
This is data
on the more
demanding
hot case (cold
case behaves
better).
John W. MacKenty
TIPS Presentation 29 November 2007
9
Image Stability (cont.)
CEI Spec:
UVIS <10mas,
IR <20mas in
200 minutes (~2
orbits).
Well within spec
during 3 hours
of stable orbital
cycling.
John W. MacKenty
TIPS Presentation 29 November 2007
10
Image Stability (cont.)
Spec exceeded for
steepest rate of change
after thermal simulation
of a worst case pointing
slew: 15-20 mas vs.
spec of 10mas/200min
in UVIS; slightly
greater than spec of
20mas/200 min for IR.
Still examining data,
realism of slew (might
have been too severe);
but if no obvious “easily
fixed cause” emerges,
likely to have to waive
this violation. Affects
dithering precision, not
single-exposure image
quality.
John W. MacKenty
TIPS Presentation 29 November 2007
11
IR Thermal Background
• IR thermal background
results vs. filter modeled
remarkably accurately by
M. Robberto.
• Extrapolation to in-flight
performance with FPA165
(higher QE, longer
wavelength cutoff) is well
within spec and within the
assumptions in our
sensitivity calculations.
John W. MacKenty
TIPS Presentation 29 November 2007
12
SOFA Repeatability
•
•
•
Used tilt of G280 spectrum to measure repeatability of wheel #1
position over 26 moves, using 2 different homing methods
Very repeatable: scatter of spectrum tilt angles corresponds to
0.01 wheel steps
Negligible effect on spectral tilt of grism mode or on external flat
field performance
John W. MacKenty
TIPS Presentation 29 November 2007
13
TV2 Analysis
•
TV2 data continues to be analyzed
– ISR 2007-26: WFC3 TV2 Testing: UVIS-2 Dark Frames and Rates -- A. R. Martel 02 Nov
2007
– ISR 2007-25: WFC3 TV2 Testing: IR Channel Non-linearity Correction and Unstable Pixel
Masking -- B. Hilbert 01 Nov 2007
– ISR 2007-24: WFC3 TV2 Testing: UVIS Filtered Throughput -- T. Brown 26 Oct 2007
– ISR 2007-23: WFC3 TV2 Testing: IR Channel Throughput -- T. Brown 23 Oct 2007
– ISR 2007-22: WFC3 TV2 Testing: UVIS-2 Amp B Anomaly -- S. Baggett, A. Waczynski 19
Oct 2007
– ISR 2007-21: WFC3 TV2 Testing: UVIS Channel Glint -- T. Brown 17 Oct 2007
– ISR 2007-20: WFC3 TV2 Testing: System Throughput on the UVIS Build 2 Detector -- T.
Brown 11 Oct 2007
– ISR 2007-19: WFC3 TV2 Testing: UVIS-2 Gain Results -- S. Baggett 14 Sep 2007
– ISR 2007-18: WFC3 TV2 Testing: Image Stability -- T. Brown 28 Aug 2007
– ISR 2007-17: WFC3 TV2 Testing: UVIS Shutter Stability and Accuracy -- B. Hilbert 16 Aug
2007
– ISR 2007-16: WFC3 TV2 Testing: IR Channel Ghosts and Baffle Scatter -- T. Brown 15 Aug
2007
John W. MacKenty
TIPS Presentation 29 November 2007
14
UVIS Detectors
John W. MacKenty
TIPS Presentation 29 November 2007
15
UVIS Throughput (cont.)
John W. MacKenty
TIPS Presentation 29 November 2007
16
UVIS Detector Status
•
UVIS1 (Prime flight detector)
–
–
–
–
Used in TV#1 and has best science performance
Developed short on AmpB due to metal particle on flex lead
Re-assembled but TEC performance declined during re-testing at Ball
TEC removed – column was cracked probably due to thermal stress
• Continuing uncertainty between over-testing or anneal ramp methodology
• Modification to MEB boards and operating procedures in instrument to soften ramp
– TEC replaced, reassembled, disassembled to fix glint, found more particles
– Proceeded to protect flex leads with “paint on” covering
•
UVIS2 (Spare flight detector)
– Acceptance testing deferred in 2004 for cost reasons
– TEC lost 10 degrees of cooling capability after acceptance testing
– Used for TV2 but serious lien against TEC (probably cracked)
•
UVIS3 (Backup flight detector – new start)
– Improved TEC and Flex Leads
– Delivered CCDs to Ball with science performance between UVIS1 and UVIS2
– Current estimate is delivery of acceptance tested assembly to GSFC March 08
John W. MacKenty
TIPS Presentation 29 November 2007
17
IR Detector Status
•
•
•
•
IR2 (FPA 64) was used for TV1. This
substrate ON detector has proton induced
glow performance concern but is
otherwise healthy.
IR1 (FPA129) is now in WFC3 for TV2.
This device has 10-12% hot pixels but
good QE and could be flown.
IR3 (FPA150) is assembled and has
passed acceptance testing at Ball
Aerospace. [Shown as right during
assembly.] – FLIGHT SPARE
IR4 (FPA165) is assembled and passed
acceptance testing at Ball. The detector
assembly will be installed into WFC3 in
early December. –FLIGHT DETECTOR
John W. MacKenty
TIPS Presentation 29 November 2007
18
IR Detector QE
John W. MacKenty
TIPS Presentation 29 November 2007
19
IR Detector Dark Current
John W. MacKenty
TIPS Presentation 29 November 2007
20
Closing Remarks
• CP is out next week
– WFC3 Instrument Handbook is done
– Kudo’s to Howard Bond, Jessica Kim Quijano and the
entire team!
• Onwards to TV3!
John W. MacKenty
TIPS Presentation 29 November 2007
21