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In-Flight Anomalies and Radiation Performance of NASA Missions -
Selected Lessons Learned
Kenneth A LaBelCo- Manager NASA Electronic Parts and Packaging (NEPP) Program
Group Leader Radiation Effects and Analysis Group (REAG)NASAGSFC
kenlabelnasagov301-286-9936
httpneppnasagov
httpsntrsnasagovsearchjspR=20090004168 2018-05-08T235216+0000Z
2In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Outline of Presentation
bull Investigative Approachbull An Optocouplerrsquos Talebull On the Matter of Small Probabilitiesbull Whatrsquos with the Noise Spikesbull The Meaning of an Upset in a Fiber Optic Linkbull Considerations
Latent damage sites device did not fail during ground irradiationbut at some time afterward during operation
Could this have been observed in-flight
3In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Anomaly Resolution ndash Root Cause Investigation for Radiation Engineers
bull Determine orbital location and time of eventndash Look for the obvious such as solar events or South Atlantic
Anomaly (SAA)bull Review electronic parts list for potential sensitive devicesbull Review identified device in specific circuit application
ndash Factors such as duty cycle operating speed voltage levels and so forth
bull Obtain existing SEE dose and damage data or gather new datandash Compare applications between in-circuit and ground datandash Perform ground testing if needed
bull Determine risk probabilitiesndash SEE rates etcndash Failure potential
bull Recommend mitigative action(s) if possible
4In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
An Optocouplerrsquos Tale - Background
bull Optocouplersndash Used extensively for the isolation of signals between
systems or boxesndash Translate electrical signals to optical then back to
electricalbull What radiation-induced failure modes may exist
ndash Long-term degradation such as current transfer ratio (CTR) ndash outputinput
ndash Single particle eventsbull Photodiodes for example have a history of being used as
energetic particle detectors
Typical Block Diagram of an Optocoupler
5In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
An Optocouplerrsquos Tale ndash NASArsquos Most Famous Science Spacecraft
bull Hubble Space Telescope (HST)ndash Flying for over 18 yearsndash Tremendous scientific discoveries (as well as gorgeous images)
bull HST has had several servicing missions (SM) ndash New instrumentsndash System upgrades and maintenance
bull On the SM2 launched Feb 14th 1997 two new instruments were installed
ndash Multiple anomalies were observed during the on-orbit engineering calibration for these instruments
ndash HSTrsquos main radiation concern is SAA
6In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
An Optocouplerrsquos Tale ndash Resolving the Anomaly
bull What steps were needed to determine ROOT CAUSE and actionndash Review of environment during anomalies
bull All events occurred in the SAAndash Review of parts list
bull Optocoupler highlighted as most likely candidatendash Review of circuit application
bull SETs simulated showing possible causendash SET could trigger a high-voltage portion of the instrument and cause failure
ndash Review or gather radiation test databull No data existed accelerator test performed
0
1
2
3
4
5
6
0 100 200 300 400 500 600
(ns)
Am
plitu
de (V
)
0
1x10-7
2x10-7
3x10-7
0 20 40 60 80 100Angle of Incidence (degrees)
Dev
ice
Cro
ss s
ectio
n (c
m2 )
Typical Measured TransientDuring Proton Irradiation
63 MeV Proton-InducedTransients on Suspect Device
Versus Angular Incidence
7In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Optocoupler ndash Final Analysisbull What steps were needed to determine ROOT CAUSE and action -
continuedndash Determine risk probability (ie upset rates)
bull Optocouplers are not just electricalbull Considerations for tools beyond CREME96 began with this and
related workndash Determine actions to mitigate or reduce risk
bull In-flight hardware is not easily modified o(ndash FPGAs improve this ability (but not here)
bull Operational change installed via software updatendash No instrument operation during SAAndash Critical science was NOT impacted but some science data loss
incurred
8In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
On the Matter of Small Probabilities - Background
bull Solid State Recorders (SSRs)ndash A means for storing science data on-board a spacecraftndash Use high-density memory ICs for densitypower advantages
bull SRAM (early 1990rsquos) bull DRAM (mid-1990rsquos and later) bull Flash (being considered)
bull DRAMs What radiation-induced failure modes may existndash TID
bull Traditional leakage increases cell failures etchellipndash SEE
bull Destructive SEL stuck bitsbull Upset bitmultiple bits block errors mode errors SEFI
1 Gb SDRAM circa 2006Feature size is 90nm
9In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
On the Matter of Small Probabilities ndash NASArsquos Most Famous Science Spacecraft (yet again)
bull On the SM2 Feb 14th 1997 a new SSR was installed to increase data storage capacityndash HST passes through the SAA several times daily
bull Bit upsets tracked fairly well with predicted rate based on ground data (3 samples one proton energy)
bull HOWEVER two more complex anomalies were observedndash Each had ~ 100 bits in error (block)ndash Block was not corrected by a re-write
ndash Project in panic
HST SSR utilizesIrvine Sensors DRAM Modules
Comprised of 16 Mb IBM Luna DRAMs
10In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
On the Matter of Small Probabilitiesndash Resolving the Anomaly
bull What steps were needed to determine ROOT CAUSE and actionndash Review of environment during anomaly
bull SAAndash Review of parts list
bull Memory controller was rad-hardbull DRAM was not
ndash Review of circuit applicationbull Circuit application was the same as in ground testing (refresh rate
etc)ndash Review or gather radiation test data
bull Proton data no observed block errors (sample size = 3 w 1x environment fluences)
bull HOWEVER heavy ion data exhibited these type of events at low LETsndash Proton events would be expectedndash New test data required for statistics on 1440 device usage
bull With 1440 devices being used for this SSR applicationndash Expected event cross-section of ~a few E-13 cm2 based on 2 events in 9
months versus (predicted) in-flight proton fluence
11In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
On the Matter of Small Probabilitiesndash Final Analysis
bull Review or gather radiation test data (contrsquod)ndash New test undertaken with protons with 100 die and to higher
proton fluence levelsbull 9 events observed with proton fluences ~100x over expected HST
expected levelsndash 2 different event signatures noted
raquo block (columnrow) errorsraquo weak columns (suspect data ndash sometimes good sometimes bad)
bull Determine risk probability (ie upset rates)ndash Predicted error rate of 22yr is the same order of magnitude as
observedbull Determine actions to mitigate or reduce risk
ndash Reset of mode register or power cycle clear the anomalybull Circuitry not included to provide resetbull Power cycle determined to be feasible when needed
ndash Data is Reed-Solomon (RS) Encodedraquo Probability of RS failure is low
ndash No action taken at that time
12In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike - Background
bull Linear devices such as analog comparators arendash Used extensively in instruments power data collection and
morendash Compares the voltage levels between two analog signals
bull What radiation-induced failure modes may existndash Long-term degradation is focused on
bull Enhanced low dose rate sensitivity (ELDRS) and displacement damage (in bipolars)
ndash Single eventsbull Single event transients (SETs) are the prime concern
-4
-2
0
2
4
12 10-5 14 10-5 16 10-5 18 10-5 2 10-5 22 10-5 24 10-5 26 10-5 28 10-5
Out
put V
olta
ge (
V)
Time (s)
LM139 Vcc
=+-5 δVi=800mV LET=187 MeV-cm2mg
Sample SETs induced by heavy ionsin a PMLM139 comparator
13In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike ndash Microwave Anisotropy Probe (MAP)
bull Launched June 30 2001ndash Had phasing orbits prior
to insertion in final orbitbull Reached its final orbital
position on L2 end of September 2001
bull An anomaly occurred causing a reset of the spacecraft processor on November 5 2001
14In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike ndash Resolving the Anomaly
bull What steps were needed to determine ROOT CAUSE and actionndash Review of
environment during anomaly
bull Solar eventndash Significant heavy
ion componentndash Review of parts list
bull Analog comparator (PMLM139) identified as likely problem 10-5
10-4
10-3
10-2
10-1
100
101
102
103
01 1 10
CREME96 Worst Day Model14 July 005 Nov 01
Background pre-SPE
15 April 0125 Sept 01
Inte
gral
Flu
ence
(c
m2 -s
)
LET (MeV-cm2mg)
Data from NOAASECSWO
after Dyer 2002
15In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike ndash Resolving the Anomaly (2)
ndash Review of circuit applicationbull Confirmed that LMPM139 could be the causebull Application had changed since initial parts review pre-launch
ndash Review or gather radiation test databull No documented proton sensitivitybull Heavy ion sensitivity documented as a function of the
application using existing data plus new data gathered
R=36k
LM139
LM139
LM139
R=51k
R=10k
R=15k
R=1k
R=100k
10 mF
Vref25V
Vref25V
Vref25V
+5V
+5V
AC14
AC14
AC14
AC14
AC14AC14
EEP_RESET
HW_RESET
10-7
10-6
10-5
10-4
10-3
0 5 10 15 20 25 30 35 40
FitPM139 dVi=200mVLM139 dVi=400 mVLM139 dVi=300 mVLM139 dVi=200 mVC
ross
sec
tion
(cm
2 com
para
tor)
LET (MeV-cm 2mg)
Heavy ion data
16In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike ndash Final Analysis
bull What steps were needed to determine ROOT CAUSE and action - continuedndash Determine risk probability (ie upset rates with heavy ions)
bull Additional shielding analysis performed for particle transportbull Assumption of sensitive volume thicknesses
ndash Determine actions to mitigate or reduce riskbull Event rates deemed acceptable by projectbull No action taken
Sensitive volumethickness
(μm)
GCR SET rateCREME96 solar maximum
(event comparator-day)
Solar EventCREME96 worst day
(event comparator-day)
10 18E-3 51E-1
15 17E-3 30E-1
20 16E-3 18E-1
30 15E-3 65E-2
40 13E-3 44E-2
60 99E-4 34E-2
17In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Meaning of an Upset in a Fiber Optic Link (FOL) - Background
bull FOLsndash MIL-STD-1773 implementation (1 MHz)
used since the early 1990rsquos in many NASA systems
ndash Transmits electrical data and command signals tofrom optical
bull What radiation-induced failure modes may existndash Similar to optocouplersndash SEUs imply single or multi-bit errors
bull Photodiodes have a history of being used as energetic particle detectors
bull Errors are temporal via photodiodendash Transients may affect more than one
clock cyclebull High-speed electrical circuits also
sensitivebull Major impact is on data bit error rate
(BER)
Representative FOL architecture
18In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Meaning of an Upset in a Fiber Optic Link (FOL)- Background (contrsquod)
bull Original MIL-STD-1773 transceivers used Si photodiodesndash Sensitive to direct ionization from protons
bull Implies high bit error rate (BER) for space applicationsndash Angle of incidence optical power budget and proton energy effects
notedbull This forced the usage of protocol fault-tolerant features to be
implemented (message retries)ndash Used successfully in NASA misions
bull BUT reduced effective bus bandwidth by ~50bull For higher data rate systems this hardening solution may not be applicable
100E-11
100E-10
100E-09
100E-08
100E-07
100E-06
-30 -25 -20 -15 -10 -5 0
Link atten in dB
Erro
r Cro
ss s
ectio
n in
cm2
Errors observed
No errors observed Ground data illustratingthe effect of optical power budget
on radiation performance
19In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Meaning of an Upset in a Fiber Optic Link (FOL)- Making a Better Mousetrap
bull Hardening methodologies exploredndash Change of optical wavelength from 850 nm to 1300 nm light showed
improved SEU tolerance bull Reduced volume of photodiode
ndash Receiver noise filtering techniques and optical power budgets also help
ndash Higher data rate development (20 MHz) ndash AS1773bull Flown as an experiment on Microelectronics and Photonics Testbed (MPTB)
ndash Boeing DR1773 Transceivers
FPGAELECTRICAL8051-BASED
DATACOLLECTIONS
POWERSUPPLIES
IN-LINEATTENUATORS
OPTICAL
OUT 2OUT 1
MPTB DR1773 Test Board
20In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Meaning of an Upset in a Fiber Optic Link (FOL) ndash MPTB Performance
bull MPTB launched in 1997ndash 6 years of in-flight
performance in a highly elliptical orbit (HEO)
bull Transceivers were operated in two modesndash ED mode used a
physical contact (PC) polished fiber optic terminal
ndash DE mode used a flat polished connector (air gap)
bull Which do you think would work better
21In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Meaning of an Upset in a Fiber Optic Link (FOL) ndash In-Flight
bull Did the hardening effort pay offED and DE bit error rates by Year
YearED BER DE BER
1997 1738E-12 NA
1998 4224E-14 3787E-11
1999 3855E-14 5303E-11
2000 0 8501E-11
2001 8168E-15 NA
2002 0 NA
0
50
100
150
200
250
300
350
400
157
170
183 52 73 86 114
142
189
218
260
303
331 8 34 61 74 133
146
159
172
185
198
259
272
285
Julian Day of Year
Num
ber
of U
pset
s
UpsetsUpset Average = 103667
1998 1999 2000
MPTB Transceiver DE Mode 1998-2000 Orbits 0036-3111
Physical contact Air Gap
Few errors were noted on the ldquogoodrdquo PC
22In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Considerationsbull Methodical process for anomaly review takes into account
ndash Environmentndash Selected partsndash Designndash Existing radiation test data andor new datandash Impact (ie risk probability)ndash Actions (mitigative or otherwise)
bull Notesndash Design and parts list reviews are good for flight programs
bull BUT any changes later in design process need to be reviewed as well
ndash Protons arenrsquot always the cause of anomalies during solar events
bull Solar heavy ions must be taken into accountndash System design and not just device radiation tolerance needs
to be taken into accountbull Mechanical issues for example can be related (as in the FOL
example)ndash Spacecraft charging effects not discussed but should be
considered as wellbull Can charging in plastic packages be the next SEU
In-Flight Anomalies and Radiation Performance of NASA Missions -
Selected Lessons Learned
Kenneth A LaBel
Co- Manager NASA Electronic Parts and Packaging (NEPP) Program
Group Leader Radiation Effects and Analysis Group (REAG)
NASAGSFC
kenlabelnasagov
301-286-9936
httpneppnasagov
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Outline of Presentation
Latent damage sites device did not fail during ground irradiation
but at some time afterward during operation
Could this have been observed in-flight
Takeaway message look beyond the obvious at times
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Anomaly Resolution ndash
Root Cause Investigation for Radiation Engineers
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
An Optocouplerrsquos Tale - Background
Photodiodes for example have a history of being used as energetic particle detectors
Typical Block Diagram of an Optocoupler
Typically these photodiode devices are shaped as thin cylinders with a depletion depth dependent on the optimized optical wavelength response In the case of indirect bandgap material such as Si large depleted volumes are required to attain adequate light absorption As a result these devices have an increased susceptibility to proton transients as compared to smaller diodes
The charge gathered by for example a proton strike on the photodiode is amplified and propagated to the output circuitry of the optocoupler If the transient is of sufficient pulsewidth and voltage amplitude an external effect may be observed For lesser photodiode events the follow-on circuitry filters out the transient such that no observable output effect is noted Factors that affect the circuitrsquos transient filtering performance include bandwidth slew rate circuit gain and power supply voltage
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
An Optocouplerrsquos Tale ndash
NASArsquos Most Famous Science Spacecraft
NASA recently announced itrsquos NEXT SM
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
An Optocouplerrsquos Tale ndash
Resolving the Anomaly
All events occurred in the SAA
Optocoupler highlighted as most likely candidate
SETs simulated showing possible cause
SET could trigger a high-voltage portion of the instrument and cause failure
No data existed accelerator test performed
Typical Measured Transient
During Proton Irradiation
63 MeV Proton-Induced
Transients on Suspect Device
Versus Angular Incidence
A
n
g
l
e
o
f
I
n
c
i
d
e
n
c
e
(
d
e
g
r
e
e
s
)
0
1
x
1
0
-
7
2
x
1
0
-
7
3
x
1
0
-
7
0
2
0
4
0
6
0
8
0
1
0
0
Device Cross section (cm2)
Why was this missed before flight Traditionally optocoupler operational frequencies were low (lt100 khz) and particle-induced transients were not passed on to follow-on circuitry Newer higher-speed devices allowed these transients to propagate
Results from the ground testing enabled better test methodologies (proton angles and energy requirements) and approaches for mitigation
0
1
2
3
4
5
6
0
100
200
300
400
500
600
(ns)
Amplitude (V)
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Optocoupler ndash Final Analysis
Optocouplers are not just electrical
Considerations for tools beyond CREME96 began with this and related work
In-flight hardware is not easily modified o(
FPGAs improve this ability (but not here)
Operational change installed via software update
No instrument operation during SAA
Critical science was NOT impacted but some science data loss incurred
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
On the Matter of Small Probabilities - Background
SRAM (early 1990rsquos)
DRAM (mid-1990rsquos and later)
Flash (being considered)
Traditional leakage increases cell failures etchellip
Destructive SEL stuck bits
Upset bitmultiple bits block errors mode errors SEFI
1 Gb SDRAM circa 2006
Feature size is 90nm
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
On the Matter of Small Probabilities ndash
NASArsquos Most Famous Science Spacecraft (yet again)
Bit upsets tracked fairly well with predicted rate based on ground data (3 samples one proton energy)
HOWEVER two more complex anomalies were observed
Each had ~ 100 bits in error (block)
Block was not corrected by a re-write
Project in panic
HST SSR utilizes
Irvine Sensors DRAM Modules
Comprised of 16 Mb IBM Luna DRAMs
These same DRAMs have been flown on the famous MPTB experiment
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
On the Matter of Small Probabilitiesndash
Resolving the Anomaly
SAA
Memory controller was rad-hard
DRAM was not
Circuit application was the same as in ground testing (refresh rate etc)
Proton data no observed block errors (sample size = 3 w 1x environment fluences)
HOWEVER heavy ion data exhibited these type of events at low LETs
Proton events would be expected
New test data required for statistics on 1440 device usage
With 1440 devices being used for this SSR application
Expected event cross-section of ~a few E-13 cm2 based on 2 events in 9 months versus (predicted) in-flight proton fluence
Why was this missed before flight
With such a low LETth one would expect proton-induced SEEs as well However proton SEE testing of 3 die provided a mixed result no block SEFIs were observed This implies a low sensitivity for block SEFI occurrence (ie limiting cross-section) The question is further expanded how good is the test fidelity with a sample size of 3 (even with overtest conditions) when designing for a SSR using 1440 devices The HST program noted that no events were observed with protons and deemed it a non-issue for their mission The project chose to proceed with the uncertainty associated with the concept of a limiting cross-section
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
On the Matter of Small Probabilitiesndash
Final Analysis
9 events observed with proton fluences ~100x over expected HST expected levels
2 different event signatures noted
block (columnrow) errors
weak columns (suspect data ndash sometimes good sometimes bad)
Circuitry not included to provide reset
Power cycle determined to be feasible when needed
Data is Reed-Solomon (RS) Encoded
Probability of RS failure is low
No action taken at that time
In order to perform a better prediction of in-flight anomaly occurrence a further proton irradiation was performed utilizing a new test plan aimed at simulating a 1440 die SSR in the HST orbit The expected proton fluence for Egt25MeV for the HST orbit is ~3E9 p+cm2year behind 100 mills of Al shielding With 2 events occurring in ~9 months wersquod expect a cross-section on the order of a few E-13 cm2die (this number actually depends on the percent of the SSR memory in use)
It should be noted that the error bars for the in-flight prediction are rather large (factor of 2 or more) This is due to
the small number of anomalies observed during ground testing (9 in 100 die)
the actual proton environment at the die level (probably gt100 mills effective Al shielding) and
the actual percent of SSR memory in use (an error could occur in an unused portion and it would not be discovered until that block of memory is accessed)
From an applications perspective there are two particular items of note here the need for fault-tolerant system design for anomalies such as that observed by the HST SRR and the importance of performing statistically significant ground tests to simulate space usage where large numbers of die are used
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike - Background
Enhanced low dose rate sensitivity (ELDRS) and displacement damage (in bipolars)
Single event transients (SETs) are the prime concern
Sample SETs induced by heavy ions
in a PMLM139 comparator
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike ndash
Microwave Anisotropy Probe (MAP)
MAP measures the anisotropy of the cosmic background radiation
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike ndash
Resolving the Anomaly
Solar event
Significant heavy ion component
Analog comparator (PMLM139) identified as likely problem
Data from NOAASECSWO
after Dyer 2002
Circuit review had taken place during design phase and SETs were reviewed no issues
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike ndash
Resolving the Anomaly (2)
Confirmed that LMPM139 could be the cause
Application had changed since initial parts review pre-launch
No documented proton sensitivity
Heavy ion sensitivity documented as a function of the application using existing data plus new data gathered
Heavy ion data
R=36k
LM139
LM139
LM139
R=51k
R=10k
R=15k
R=1k
R=100k
10 mF
Vref
25V
Vref
25V
Vref
25V
+5V
+5V
AC14
AC14
AC14
AC14
AC14
AC14
EEP_RESET
HW_RESET
SO how was this missed to begin with
Designer KNEW about SETs and original design had a larger voltage differential (1V) which is much less sensitive for SETs
Requirements changed AFTER review was performed on design and a smaller voltage differential was used equaling enhanced sensitivity to SETs (200 mV)
Of import is that solar heavy ions were the cause and not protons
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
Whatrsquos With the Noise Spike ndash
Final Analysis
Additional shielding analysis performed for particle transport
Assumption of sensitive volume thicknesses
Event rates deemed acceptable by project
No action taken
Sensitive volume
thickness
(
m
m)
GCR SET rate
CREME96 solar maximum
(event
comparator-day)
Solar Event
CREME96 worst day
(event
comparator-day)
10
18E-3
51E-1
15
17E-3
30E-1
20
16E-3
18E-1
30
15E-3
65E-2
40
13E-3
44E-2
60
99E-4
34E-2
Sometimes we get lucky anomaly rates are low enough not impact mission performance However this is not always the case
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Meaning of an Upset in a Fiber Optic Link (FOL) - Background
Photodiodes have a history of being used as energetic particle detectors
Errors are temporal via photodiode
Transients may affect more than one clock cycle
High-speed electrical circuits also sensitive
Major impact is on data bit error rate (BER)
Representative FOL architecture
In-Flight Electronics and Radiation ndash Presented by Kenneth A LaBel SERESSA West Palm Beach Fl 1222008
The Meaning of an Upset in a Fiber Optic Link (FOL)- Background (contrsquod)
Implies high bit error rate (BER) for space applications
BUT reduced effective bus bandwidth by ~50
For higher data rate systems this hardening solution may not be applicable
Ground data illustrating
the effect of optical power budget
on radiation performance