SMOV4 Update: ACS Status
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David Golimowski (TIPS/JIM 16 Jul 2009)
Outline
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Summaries of Functional Test and Optimization Campaign
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WFC and SBC Performance and Characteristics
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Implications of SI C&DH Anomaly (HSTAR 11880)
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Assessment of Day 174 Suspend (HSTAR 11895)
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SMOV Status and Forward Plan
TIPS/JIM 16 Jul 2009
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ACS-R Functional Test and
Optimization Campaign - 1
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ACS-R hardware successfully installed on 16 May 2009 during EVA-3
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WFC and SBC passed Aliveness and Functional Tests; HRC not recovered
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Day 146 (26 May): WFC 12-hour anneal performed; pre- and post-anneal dark
frames show little change indicating that 18 month hiatus at ambient -10 C was
sufficient to anneal nearly all temporary hot pixels.
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Day 148 (28 May): WFC Optimization Campaign commenced
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Day 150 (30 May): SBC UV contamination check; BEA exit deemed safe
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Optimization Campaign contained general WFC Performance Summary and
multiple exploratory tests involving changes in bias and clock voltages and data
transmission timing. Tests showed that all pre-failure settings remained valid for
CEB-R operations and that no changes in default settings were warranted.
TIPS/JIM 16 Jul 2009
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WFC Bias and Dark Frames
Superbias from Prop 11369
(SMOV CCD Functional Test)
TIPS/JIM 16 Jul 2009
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Superdark from Prop 11369
(SMOV CCD Functional Test)
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WFC Linearity and Full Well
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Photon Transfer Test from Iteration 1 of O.C.
(Amplifier D, Dual-Slope Integrator)
TIPS/JIM 16 Jul 2009
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WFC Performance Summary
January 2007
(measured)
May 2009*
(projected)
Problematic*
Read noise
(e-; gain = 2)
C&S: 5.5
DSI: 4.0
10
DSI: 3.9-4.7
C&S: 4.4-5.7
Dark current (e-/pix/hr)
10.7
15
100
20-25
Hot pixels (%)
0.68
1.1
1.5
1.1
Full well depth (e-)
84,000
84,000
40,000
~80,000
Non-linearity (%)
< 0.1
< 0.1
0.5
< 0.2
Metric
Post SM4
(measured)
(exp time > 2 s)
CTE (1620 e-)
0.999949
0.999921
0.9999
0.99989
Cross-talk
4x10-5
4x10-5
4x10-4
1x10-4
Bias shift** (%)
0.02
< 0.1
< 0.2
0.02-0.30
(before correction)
* Projected and problematic values from Gilliland et al. 2008 (TIR ACS 2008-04) .
**Residual bias shift after analytical correction of signal-dependent effect.
TIPS/JIM 16 Jul 2009
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ACS-R Functional Test and
Optimization Campaign - 2
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Optimization Campaign truncated on 3 June 2009 after Iteration 2
 Performance matched or exceeded projections and expectations
 VOD offsets of < -1 V produce anomalous behavior in amps C and D that
mimic charge-injection but remain unexplained by Tiger Team
 HSTMO and Project elect to proceed with WFC default configuration
and continue “off-line” investigation of VOD anomaly
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Dual-Slope Integrator selected as default mode of ASIC pixel sampling
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Low-frequency bias variations and signal dependent “bias shift” can be
effectively removed during post-image processing
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Bias striping pattern varies among quadrants and between frames; caused by 1/f
noise (1 mHz to 1 Hz) generated with ASIC during setting of bias voltage offset.
Striping appears constant across rows of CCD, so may be removable.
TIPS/JIM 16 Jul 2009
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VOD (Reset Drain) Anomaly
VDD: +27V, VLG: -3V
(defaults)
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Bias
VOD: +14V
(default is +15V)
Illumination 1
Illumination 2
TIPS/JIM 16 Jul 2009
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SBC UV Contamination
F125LP
Bright Earth photopolymerizes
contaminants onto pickoff mirror
Pre SM4 (short)
Post SM4 (short & long)
F150LP
Delta Mag (Pre-Post SM4)
F115LP = -0.034 +/- 0.017
F125LP = -0.014 +/- 0.013
F140LP = -0.019 +/- 0.015
F150LP = 0.002 +/- 0.015
F165LP = 0.008 +/- 0.015
TIPS/JIM 16 Jul 2009
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SIC&DH Anomaly (HSTAR 11880)
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HST safed on Day 166 (15 June) after failure of SIC&DH toggle test; all SI
commanding lost; SIs remain in state at time of SIC&DH failure; SMS
continues to execute; HST continues to slew
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Tiger Teams assembled to investigate:
 Dangers to SI detectors (MAMA, CCD, IR) due to overexposure during
Bright Earth crossings, SAA crossings, and slews across bright stars
 Potential polymerization of contaminants on optics in UV channels
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Implications for ACS:
 No danger to CCDs; WFC science can continue unimpeded
 SBC MAMA vulnerable to catastrophic damage during BE crossings
 Impact of SAA on MAMA unknown because HV normally turned off
 ACS optics exposed to 100s of hrs of BE crossings with no ill-effects
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SBC concerns resolved by 486 FSW revision that automatically shuts down
MAMA HV after future (expected) SIC&DH anomalies
TIPS/JIM 16 Jul 2009
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Day 174 Suspend
(HSTAR 11895)
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ACS suspended on 23 June as result of 2 Error Status Buffer messages:
 ACS 955: CEB Command Max Retries Exceeded
 ACS 1002: NED ASIC Not Alive
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Status at time of suspend:
 No observations executing or lost
 All monitored currents and voltages normal
 ASIC & FPGA properly initialized & functioning after SMS 173 reboot
 Error occurred during NED collection cycle (CS to ASIC comm broken)
 HST orbital position far from SAA
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Tiger Team formed on 24 June and identified 2 possible causes:
 ASIC Status Line raised (informs FPGA of bit anomaly or comm error)
 FPGA reset in response to SEU of power regulator
TIPS/JIM 16 Jul 2009
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FPGA/ASIC Relationship
Ack 8Mbit/s
ScienceData8Mbit/s
MEB
Resetb
FPGAMEB
Interface
Soft_Reset
Logic / Memory
DataIn 8Mbit/s
ADCs
SIDECAR
DACs
FPGA
DataClk 8MHz
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OutA
OutB
OutC
OutD
Biases
22
Interrupt
Status
DONE%
SHUTTER
DONE%
SHUTTER
RUNNING
CLK_EN_Y
CLK_EN_X
BIAS_CONNECT
RUN_EN%
LVPS
PS_CLK
45 kHz
TIPS/JIM 16 Jul 2009
Clock I/O
CCD Clocks
12
Clamp/Sample
Dual Slope
3
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Possible Causes of
Day 174 Suspend
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ASIC Status Line scenario not favored because it produces only ACS 955
ESB message and does not explain “ASIC Not Alive” failure
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Radiation test reports now available show ambient heavy-ion flux sufficient
to upset power regulator once every ~100 days
 SEU causes small voltage drop that triggers Power On Clear circuit
 FPGA and ASIC both reset; only FPGA reboots
 Scenario explains both ACS 955 and ACS 1002 ESB messages
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Event will happen again, but signature of anomaly will depend on timing of
SEU with phase of FPGA/ASIC/telemetry duty cycle
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Tiger Team investigating FSW changes to inhibit suspend action in this
particular instance of ACS 955 error message
TIPS/JIM 16 Jul 2009
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Status and Forward Plan
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Both SBC and WFC have had successful and spectacular “first light”
external observations. (No pretty pictures -- sorry!)
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WFC focus is -2.5 m off nominal. Other SIs will be made confocal with
WFC and secondary mirror will be moved next week.
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All SBC and WFC SMOV programs have been executed and data analysis is
underway. Several SMOV programs (all HRC; WFC half-speed; coarse &
fine corrector alignment) were unnecessary and dropped.
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VOD anomaly and its possible beneficial use to mitigate CTE through chargeinjection will being investigated
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Changes to FSW being considered to prevent suspend after SEU of CEB-R
(expected every 100 days)
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ACS cleared for GO Science!!!
TIPS/JIM 16 Jul 2009
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