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Transcript of 1 Shuttle Derived Launch Vehicle Dynamic Abort Risk Evaluator (DARE) Gaspare Maggio Chris Everett...
![Page 1: 1 Shuttle Derived Launch Vehicle Dynamic Abort Risk Evaluator (DARE) Gaspare Maggio Chris Everett Tony Hall – Section Manager – Project Manager – Development.](https://reader036.fdocuments.in/reader036/viewer/2022062407/56649cbb5503460f94982f95/html5/thumbnails/1.jpg)
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Shuttle Derived Launch Vehicle Dynamic Abort Risk Evaluator
(DARE)Gaspare Maggio
Chris EverettTony Hall
– Section Manager– Project Manager– Development Lead
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Topics to be Discussed
• DARE Background– DARE Purpose & Scope– Space Shuttle DARE– DARE Methodology– Example Trade Studies
(SSME Throttle Up, Nz Pullout)
• DARE Model– Abort Initiators– Pivotal Events– Module Examples– Probabilistic Framework
• Application to Constellation– CLV Application– Expansion for Lunar Mission
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• DARE dynamically evaluates abort effectiveness– Conditional analysis
• Given an abort, what is the subsequent probability of abort success/failure
• Aborts are defined by a failure initiator and failure time– Dynamic evaluation
• The risk evaluation in DARE is determined both probabilistically & parametrically, accommodating a broad range of initial conditions (vehicle configurations, abort initial conditions)
• The DARE model accommodates random uncertainties, such as the time of subsequent system failures
• The current scope of DARE is ascent abort (expandable to other mission phases)– Space Shuttle (heritage capability)– Shuttle-derived Launch Vehicles (new capability)
DARE Purpose
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Background - Shuttle DARE
• Space Shuttle PRA 1995– First quantitative probabilistic risk model
created for the Space Shuttle– Addressed nominal mission
• DARE 1997-present– Model to determine abort risks and perform risk trade
studies(1995 PRA did not consider abort risks)
– Address the need to include abort risk assessment as part of the overall Space Shuttle risk management process
– Compliment, and eventually integrate into, nominal-mission Space Shuttle ascent risk analysis
• Inclusion of Shuttle-Derived Launch Vehicles– New capability: initial development completed May 2005– DARE Shuttle & SDLV
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FutronBarney Roberts
NASA JSC/SAICFeng HsuMark BiglerMichael StewartJohn Pruitt
BoeingDavid AlmonzaEd DigonGregory Manich
USAKevin ButlerDouglas LufkinMishawn MielkeStacy Sklarczyk
NASA MSFCPhilip Benefield Joseph HastingsRandy Humphries, Jr.Michael KynardFayssal Safie Len Worland
RocketdyneRobert Biggs
Core DARE Team:Edward M. Henderson
**Richard Heydorn**Dennis Bentley Roger BoyerAngela Braun Leroy Cain Carlisle Campbell, JrBarbara Conte John Craft Steve DawsonDaniel Deger Gary DuncanRobert Ess William (Andy) Foster Stephen N. Frick, LCDR Mark HammerschmidtJim HarderJoshua Hardy Scott HartmanMack HimelNorman Knight
**Jan Railsback **Catherine KoernerHoward Law Robert LawAlice LeeSteve LindseyRobert Navarro-LightholderGregory OliverMunish Patel J. Ken PattersonWilliam PowersHenk Roelant John ShannonCarson SparksCindy SwitzerDavid Thelen David Whittle Jeff Williams Philip Wilson Karon Woods
NASA JSC
UHCLKevin ButlerTom English
NASA HQMichael StamatelatosWilliam Vesely
Independent Peer Review TeamAli Mosleh, Univ. of MarylandNathan Siu, NRC
FutronBarney Roberts
NASA JSC/SAICFeng HsuMark BiglerMichael StewartJohn Pruitt
BoeingDavid AlmonzaEd DigonGregory Manich
USAKevin ButlerDouglas LufkinMishawn MielkeStacy Sklarczyk
NASA MSFCPhilip Benefield Joseph HastingsRandy Humphries, Jr.Michael KynardFayssal Safie Len Worland
RocketdyneRobert Biggs
Core DARE Team:
Gaspare Maggio, Chris Everett, Sabrina Yazdpour, Frank Hark, Tony Hall
**Richard Heydorn**Dennis Bentley Roger BoyerAngela Braun Leroy Cain Carlisle Campbell, JrBarbara Conte John Craft Steve DawsonDaniel Deger Gary DuncanRobert Ess William (Andy) Foster Stephen N. Frick, LCDR Mark HammerschmidtJim HarderJoshua Hardy Scott HartmanMack HimelNorman Knight
**Jan Railsback **Catherine KoernerHoward Law Robert LawAlice LeeSteve LindseyRobert Navarro-LightholderGregory OliverMunish Patel J. Ken PattersonWilliam PowersHenk Roelant John ShannonCarson SparksCindy SwitzerDavid Thelen David Whittle Jeff Williams Philip Wilson Karon Woods
NASA JSC
UHCLKevin ButlerTom English
**Individuals listed were instrumental in getting the DARE project started
NASA HQMichael StamatelatosWilliam Vesely
Independent Peer Review TeamAli Mosleh, Univ. of MarylandNathan Siu, NRC
FutronBarney Roberts
NASA JSC/SAICFeng HsuMark BiglerMichael StewartJohn Pruitt
BoeingDavid AlmonzaEd DigonGregory Manich
USAKevin ButlerDouglas LufkinMishawn MielkeStacy Sklarczyk
NASA MSFCPhilip Benefield Joseph HastingsRandy Humphries, Jr.Michael KynardFayssal Safie Len Worland
RocketdyneRobert Biggs
Core DARE Team:Edward M. Henderson
**Richard Heydorn**Dennis Bentley Roger BoyerAngela Braun Leroy Cain Carlisle Campbell, JrBarbara Conte John Craft Steve DawsonDaniel Deger Gary DuncanRobert Ess William (Andy) Foster Stephen N. Frick, LCDR Mark HammerschmidtJim HarderJoshua Hardy Scott HartmanMack HimelNorman Knight
**Jan Railsback **Catherine KoernerHoward Law Robert LawAlice LeeSteve LindseyRobert Navarro-LightholderGregory OliverMunish Patel J. Ken PattersonWilliam PowersHenk Roelant John ShannonCarson SparksCindy SwitzerDavid Thelen David Whittle Jeff Williams Philip Wilson Karon Woods
NASA JSC
UHCLKevin ButlerTom English
NASA HQMichael StamatelatosWilliam Vesely
Independent Peer Review TeamAli Mosleh, Univ. of MarylandNathan Siu, NRC
FutronBarney Roberts
NASA JSC/SAICFeng HsuMark BiglerMichael StewartJohn Pruitt
BoeingDavid AlmonzaEd DigonGregory Manich
USAKevin ButlerDouglas LufkinMishawn MielkeStacy Sklarczyk
NASA MSFCPhilip Benefield Joseph HastingsRandy Humphries, Jr.Michael KynardFayssal Safie Len Worland
RocketdyneRobert Biggs
Core DARE Team:
Gaspare Maggio, Chris Everett, Sabrina Yazdpour, Frank Hark, Tony Hall
**Richard Heydorn**Dennis Bentley Roger BoyerAngela Braun Leroy Cain Carlisle Campbell, JrBarbara Conte John Craft Steve DawsonDaniel Deger Gary DuncanRobert Ess William (Andy) Foster Stephen N. Frick, LCDR Mark HammerschmidtJim HarderJoshua Hardy Scott HartmanMack HimelNorman Knight
**Jan Railsback **Catherine KoernerHoward Law Robert LawAlice LeeSteve LindseyRobert Navarro-LightholderGregory OliverMunish Patel J. Ken PattersonWilliam PowersHenk Roelant John ShannonCarson SparksCindy SwitzerDavid Thelen David Whittle Jeff Williams Philip Wilson Karon Woods
NASA JSC
UHCLKevin ButlerTom English
**Individuals listed were instrumental in getting the DARE project started
NASA HQMichael StamatelatosWilliam Vesely
Independent Peer Review TeamAli Mosleh, Univ. of MarylandNathan Siu, NRC
DARE Contributors
Gaspare Maggio, Chris Everett, Sabrina Yazdpour,Tony Hall
John Turner
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DARE Technical Validation• Ascent GN&C Abort Panel Review in September 2001
– Monte Carlo simulations for ET separation success rates were incorporated into DARE model and reviewed
• MFSC SSME Project office, SSME Reliability Estimates Review in July 2002 – SSME Project provided new SSME mean and median estimates for catastrophic
and benign shutdown failures
• Independent assessment of the RTLS risk modeling was performed in October 2001 (Barney B. Roberts, Futron Corp.)– Continue to pursue DARE modeling -- Good decision-support tool for studying
mission options to reduce risk
• Flight Techniques Panel Review in July 2002– Presented DARE model and overview
• Integrated Control Board Review in October 2002– Presented DARE model and overview as well as discussed DARE/SPRA
integration
• Independent Peer Review Report, NASA Office of Safety and Mission Assurance– DARE was independently reviewed by NASA OSMA as a pathfinder
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Comments of Note from Reviews
“The general methodological framework underlying DARE is, as a whole, technically
valid”-Independent Peer Review Report, NASA Office of Safety and Mission
Assurance, July 2003
“Good decision-support tool for studying mission options to reduce risk”
-Barney Roberts, Independent Reviewer, Sept 2001
“This is great stuff!”-Wayne Hale, Integration Control Board Review, October 2002
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DARE Methodology
Identify AbortInitiators
Determine Abort Modes / Regions
Identify Events that Dominate
Abort Risk
ProduceResults
DevelopModels / Modules
for SignificantEvents
Integrate into ProbabilisticFramework
ShuttlePRA
SDVPRA
CustomerNeeds
Flight Rulesfor Abort
Operations
DataGathering
UncertaintyAnalysis
ModelDevelopment
• Identify important abort initiators• Characterize abort operations• Identify significant abort events• Model events within dynamic,
probabilistic framework
Step 6
Step 5
Step 4
Step 3
Step 2
Step 1
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Example Shuttle Results
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DARE Ver. 3.00STS-111
SSME Throttle-Up Risk Trade
TAL (ZZA) @ 104.5%/104.5%
104.5%/106%104.5%/109%
148 s
136 s 12 124 s 24
A risk trade was performed using DARE to consider the possibility of throttling up the two remaining SSMEs after a first engine shutdown to transition to a TAL abort rather than having to conduct an RTLS
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1 in 33
RTLS risk dominated by ET separation risk
Qbar at separation reduced by increasing load limits
during Nz Pullout
Risk reduction potential quantified
~ 1 in 70
ET Separation
Percentage Risk Distribution (RTLS)STS # 114 / First Engine Shutdown = 30 sec
Mean Estimates
All Estimates Conditional on First Engine Shutdown* Other Systems Not Shown above such as Failures due to HYD, ECLSS, EPD, ET Debris HIt, Mechanical, MMOD, Orbiter Structure, SSME-MECO, TPS, and Loss of Control Due to Failure to Control C.G. are either ~0% or not applicable
ET Separation
Nz Pullout Risk Trade
0
20
40
60
80
100
120
140
160
7.5 6.6 5.6 4.6Dynamic Pressure at ET Sep (psf)Nz Target (g)
Altitude at ET Sep (kft)Max Dynamic Pressure at Pullout (psf)
To
tal a
nd
ET
Se
pa
rati
on
Ris
k (
1 in
X)
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
Nz
Pu
llou
t (1
in X
)
TOTAL LOV RISK
LOV due to ET Separation Risk
LOV due to Nz Pullout Risk
2.0 2.1 2.1 2.3 210.1 212.2 216.2 221.4 319 336 357 320
Inc
rea
sin
g R
eli
ab
ilit
yIn
cre
as
ing
Re
lia
bil
ity
Total RTLS
Nz Pullout ET Sep
0
20
40
60
80
100
120
140
160
7.5 6.6 5.6 4.6Dynamic Pressure at ET Sep (psf)Nz Target (g)
Altitude at ET Sep (kft)Max Dynamic Pressure at Pullout (psf)
To
tal a
nd
ET
Se
pa
rati
on
Ris
k (
1 in
X)
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
Nz
Pu
llou
t (1
in X
)
TOTAL LOV RISK
LOV due to ET Separation Risk
LOV due to Nz Pullout Risk
2.0 2.1 2.1 2.3 210.1 212.2 216.2 221.4 319 336 357 320
Inc
rea
sin
g R
eli
ab
ilit
yIn
cre
as
ing
Re
lia
bil
ity
Total RTLS
Nz Pullout ET SepET separation risk
sensitive to Qbar at separation
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• Current SDLV configurations modeled in DARE– In-line crew (ILC)
• 3 CLV configurations– 4 segment SRB, J-2 upper stage– 5 segment SRB, J-2 upper stage– 4 segment SRB, SSME upper stage
• CEV parametric model
– Side-mount crew (SMC)• Shuttle derived external tank, dual
SRBs, 3 SSME main propulsion• Same CEV model as for ILC
SDLV Scope
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SDLV Abort Initiators
Functional Failure/Shutdown (US) Catastrophic Fire/Explosion (US) OMS Failure to Function (CV SEP) TVC Catastrophic Failure (SRB) Booster Separation Motor Failure (SRB SEP) Interstage Separation Motor Failure (SRB SEP) Booster Separation Bolts Failure (SRB SEP) CV Separation Motor Failure (CV SEP) RSRM Propellant Failure RSRM Flex Bearing Joint Failure RSRM Nozzle Joint 1 Failure RSRM Nozzle Joint 5 Failure RSRM Other Joint Failure RSRM Structural Failure RSRM Thermal Failure RSRM Nozzle Failure
SSME Shutdown SSME Turbopump Failure SSME Nozzle Failure SSME Main Combustion Chamber Failure SSME Other Catastrophic Failure MPS Functional Failure MPS Catastrophic Failure FCS Functional Failure APU Catastrophic Failure SSME Failure to MECO SRB Functional Failure SRB Catastrophic Failure SRB Separation Functional Failure SRB Separation Catastrophic Failure RSRM Functional Failure RSRM Motor Propellant Failure RSRM Nozzle Failure RSRM Nozzle Phenolics Failure RSRM Other Insulation Failure RSRM Structural Failure RSRM OPT Joint Failure RSRM Flex Bearing Joint Failure RSRM Other Joint Failure RSRM Nozzle Joint 1 Failure RSRM Nozzle Joint 5 Failure RSRM Other Nozzle Joint Failure
Side-Mount Vehicle*In-Line Vehicle*
*Abort initiator identification and consolidation is subject to the fidelity of the PRA used to identify the failure modes. In the case of the SDLV PRA, In-Line upper-stage failures have all been grouped into a common failure mode. Additionally, some abort initiators they may be consolidated due to commonalities on one vehicle, may not necessarily share those commonalities on another vehicle.
Relevant abort initiators were transferred and modified from Space Shuttle PRA
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Pivotal EventsAscent abort pivotal events are identified in a master abort event tree and evaluated in event-specific modules
Event Descr:
Abort Initiating Failure Detected
CEV successfully separates from LV
CEV successfully stabilizes after separation
CEV abort mode is abort to orbit
Abort to orbit successful
CEV successfully performs de-orbit burn and re-entry
CEV successfully deploys landing system
CEV lands safely
Crew is safely recovered Prob_Path Description
Event Name: PEM 1 PEM 2 PEM 3 SWITCH - 4 PEM 5 PEM 6 PEM 7 PEM 8 PEM 9Event Prob: 0.999995 0.999726 0.999984 0.000000 0.999874 0.999736 0.999986 0.999000 0.999999
1 0.999994867 0.999720608 0.999704144 0 0 0 0 0 0Abort Initiating Failure Y 0.999994867 Y 0.99972574 Y 0.999983531 Y 0 Y 0.999874288 Y 0.999735677 Y 0.999986364 Y 0.999 Y 0.999999 0 OK
0N 1E-06 0 LOC
0N 0.001 0 LOC
0N 1.36358E-05 0 LOC
0N 0.000264323 0 LOC
0N 0.000125712 0 LOC
0.999704144 0.999690513 0.998690822 0.998689823N 1 Y 0.999986364 Y 0.999 Y 0.999999 0.99869 OK
9.98691E-07N 1E-06 9.99E-07 LOC
0.000999691N 0.001 0.001 LOC
1.36317E-05N 1.36358E-05 1.36E-05 LOC
1.64639E-05N 1.64685E-05 1.65E-05 LOC
0.000274259N 0.00027426 0.000274 LOC
5.13313E-06N 5.13313E-06 5.13E-06 LOC
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Example Module: Separation Failure
• Separation failure occurs if any of the following failures occurs:– Failure of separation mechanisms– Failure of the CEV to survive increased dynamic pressure
associated with abort velocity– Failure of the CEV to survive the accident environment existing in
the vicinity of the LV
SEP-FAIL
4
ACCIDENT-ENV-FAIL
5
DYNAMIC-PRESS-FAIL
6
SEP-MECH-FAIL
Faiure to surviveabort dynamic
pressure
Failure to surviveaccident environment
stresses
Failure of separationmechanisms
CEV fails todepart launch
vehicle vicinity
SEP-FAIL - CEV fails to depart launch vehicle vicinity 2006/01/25 Page 7
SEP-FAIL
4
ACCIDENT-ENV-FAIL
5
DYNAMIC-PRESS-FAIL
6
SEP-MECH-FAIL
Faiure to surviveabort dynamic
pressure
Failure to surviveaccident environment
stresses
Failure of separationmechanisms
CEV fails todepart launch
vehicle vicinity
SEP-FAIL - CEV fails to depart launch vehicle vicinity 2006/01/25 Page 7
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Event Description:
SRB EXPLOSION
SRB EXPLOSION CAUSES
EXTERNAL TANK EXPLOSION
HOT GAS PLUME CAUSES
EXTERNAL TANK EXPLOSION
Event Probability: 0% - 20% 100% 35% - 65%
RSRM Joint Failure Y Y SRB and ET Explode
N Only SRB Explodes
N Y Only ET Explodes
N Nominal Abort
Example: RSRM Joint Failure
Separation Failure ExampleFailure to survive accident environment stresses
• The event, “Failure to survive accident environment stresses” considers the various ways that each initiating event might unfold, producing a spectrum of possible environments
Accident Characteristi
cs
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180
50
100
150
200
250
300
350
400
450
500
0 50 100 150 200 250 300 350 400 450 500
Time of Abort (s)
Dis
tan
ce (
ft)
Separation Distance
0
50
100
150
200
250
300
350
400
450
500
0 50 100 150 200 250 300 350 400 450 500
Time of Abort (s)
Dis
tan
ce (
ft)
Critical Distance
Separation Failure Example Failure to survive accident stresses (continued)
• The CEV survives the accident stresses if it reaches a critical distance from the exploding launch vehicle.
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DARE Probabilistic Framework
• Dynamic abort risk evaluation is accomplished by developing the abort model within a fully probabilistic framework– Uncertainties can be associated with any modeling parameter– Statistics can be obtained on any calculated result
• DARE handles both modeling uncertainty and random uncertainty– Modeling uncertainty describes lack of knowledge about the
events being modeled, e.g.:• IVHM reliability• LES reliability• Landing system reliability
– Random uncertainty describes variability in the events being modeled, e.g.:
• CEV/LV separation distance• Accident propagation paths
• Abort effectiveness is expressed as a probability and an associated confidence:
P(successful abort) @ confidence level
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DARE Example ResultsPivotal Event Breakdown
SDLV DARE Example Results
CEV Stabilization FailureRecovery Failure
Landing Failure
Landing Sys. FailureFailure Detection Failure
CEV Separation Failure
Abort Pivotal Events
P (
Ab
ort
Fa
ilure
)
Ascent Time = 80 secondsRSRM Propellant Failure4 Segment SRB, Sinlge J-2
1
1/100,0000
1/10,000
1/1,000
1/1001/100
1/10
1/1,000,000
Mean Value
5th Percentile
95th Percentile
Key
Mean Value
5th Percentile
95th Percentile
Key
Landing and recovery modules currently contain static placeholder values
Separation failure is the event with the greatest expected risk… …and the greatest
uncertainty
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Integrated Abort Effectiveness
Overall 85% Crew Escape Effectiveness
LOM
LOC
• DARE was applied to the ILC SDLV Top-Level PRA to estimate overall CEV abort effectiveness for this configuration– Rough analysis
• For each failure mode, abort effectiveness was assessed at the midpoint of the exposure duration• 5th, 50th & 95th percentiles were used to estimate failure-mode-specific abort effectiveness densities• A few failure modes are assessed conservatively due to lack of detection lead time data
• Result: 85% mean abort effectiveness for ILC J-2S
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DARE as a Living Tool
• DARE has been designed to maximize “plug and play” capability, allowing the most current data and models to be integrated into the analysis framework
Evolving Architectures Event Descr:
Abort Initiating Failure Detected
CEV successfully separates from LV
CEV successfully stabilizes after separation
CEV abort mode is abort to orbit
Abort to orbit successful
CEV successfully performs de-orbit burn and re-entry
CEV successfully deploys landing system
CEV lands safely
Crew is safely recovered Prob_Path Description
Event Name: PEM 1 PEM 2 PEM 3 SWITCH - 4 PEM 5 PEM 6 PEM 7 PEM 8 PEM 9Event Prob: 0.999995 0.999726 0.999984 0.000000 0.999874 0.999736 0.999986 0.999000 0.999999
1 0.999994867 0.999720608 0.999704144 0 0 0 0 0 0Abort Initiating Failure Y 0.999994867 Y 0.99972574 Y 0.999983531 Y 0 Y 0.999874288 Y 0.999735677 Y 0.999986364 Y 0.999 Y 0.999999 0 OK
0N 1E-06 0 LOC
0N 0.001 0 LOC
0N 1.36358E-05 0 LOC
0N 0.000264323 0 LOC
0N 0.000125712 0 LOC
0.999704144 0.999690513 0.998690822 0.998689823N 1 Y 0.999986364 Y 0.999 Y 0.999999 0.99869 OK
9.98691E-07N 1E-06 9.99E-07 LOC
0.000999691N 0.001 0.001 LOC
1.36317E-05N 1.36358E-05 1.36E-05 LOC
1.64639E-05N 1.64685E-05 1.65E-05 LOC
0.000274259N 0.00027426 0.000274 LOC
5.13313E-06N 5.13313E-06 5.13E-06 LOC
Master Abort Event Tree
Pivotal EventsVehic
le /
Ele
ment
Set
Ris
ks &
U
nce
rtain
ties
228
32 34 37 39 40
419
1090
36 37 38 40 40
571
0
200
400
600
800
1000
1200
1400
A B C D E F G
Case Designation and FES time
MF
BF
(1
in
X M
iss
ion
s)
Block IIA
Block II
RTLSTAL
0.1 sec 40 sec 90 sec 150 sec 234 sec146.9 sec 279.4 sec
BkII/BkIIA Risk Reduction:Case A - 1- 228/419 = 46%Case B - 1- 571/1090 = 48%
BkII/BkIIA Risk Reduction:Case C - 1- 32/36 = 11%Case D - 1- 34/37 = 8%Case E - 1- 37/38 = 2.6%Case F- 1- 39/40 = 2.5%Case G- 1- 40/40 = 0%
Results
SDV DARE Example Results
CV Stabilization FailureRecovery Failure
Landing Failure
Landing Sys. Failure
Failure Detection Failure
CV Separation Failure
Abort Pivotal Events
LOC
Ascent Time = 80 secondsRSRM Propellant FailureSide-Mount Vehicle
1
1/100,000
1/10,000
1/1,000
1/1001/100
1/10
1/1,000,000
Mean Value
5th Percentile
95th Percentile
Key
Mean Value
5th Percentile
95th Percentile
Key
Landing and recovery modules currently contain static placeholder values
SDV DARE Example Results
CV Stabilization FailureRecovery Failure
Landing Failure
Landing Sys. Failure
Failure Detection Failure
CV Separation Failure
Abort Pivotal Events
LOC
Ascent Time = 80 secondsRSRM Propellant FailureSide-Mount Vehicle
1
1/100,000
1/10,000
1/1,000
1/1001/100
1/10
1/1,000,000
Mean Value
5th Percentile
95th Percentile
Key
Mean Value
5th Percentile
95th Percentile
KeySDV DARE Example Results
CV Stabilization FailureRecovery Failure
Landing Failure
Landing Sys. Failure
Failure Detection Failure
CV Separation Failure
Abort Pivotal Events
LOC
Ascent Time = 80 secondsRSRM Propellant FailureSide-Mount Vehicle
1
1/100,000
1/10,000
1/1,000
1/1001/100
1/10
1/1,000,000
Mean Value
5th Percentile
95th Percentile
Key
Mean Value
5th Percentile
95th Percentile
Key
Landing and recovery modules currently contain static placeholder values
DARE
0
50
100
150
200
250
300
350
400
450
500
0 50 100 150 200 250 300 350 400 450 500
Time of Abort (s)
Dis
tan
ce (
ft)
Pf=95%
Pf=50%
Critical Distance: CEV survival / failure interface
Separation Distance: CES Capability
5th Percentile
50th Percentile
95th Percentile
Pf=5%
0
50
100
150
200
250
300
350
400
450
500
0 50 100 150 200 250 300 350 400 450 500
Time of Abort (s)
Dis
tan
ce (
ft)
Pf=95%
Pf=50%
Critical Distance: CEV survival / failure interface
Separation Distance: CES Capability
5th Percentile
50th Percentile
95th Percentile
Pf=5%
Integration of the best available Data and Models
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• Is a particular LOC requirement reasonable and achievable?– e.g. 99% abort effectiveness at 80% confidence
• System options– LES motor
• pusher/tractor– Reentry/landing systems
• Biconic/ballistic– TPS type
• Ablative/tile
• Performance characteristics– LES acceleration– Overpressure tolerance– Dynamic pressure tolerance– LES burn time
• Concept of operations– Escape tower jettison time– ATE/ATO interface
1
4
7
10 5
10
15
20
0
10
20
30
40
50
60
70
80
90
Requirements Development Support
LES A
ccele
rati
on
(m/s
2)
LES Burn Time
(sec)
Overpre
ssure
Desig
n Limit
(psi)
Requirements Surface e.g. 99% reliability @ 80%
confidenceAbove surface: Requirement met
Below surface: Requirement not met
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• Identify and reduce the largest inhibitors of abort effectiveness
• Identify and reduce the largest uncertainties in abort effectiveness
US Cat
US Shutdown
RSRM Nozz. J-1 Fail
RSRM Prop. Fail
TVC Cat. (SRB)
0.000100
0.001000
0.010000
0.100000
1.000000
T = 80s
T = 250s
…Failure mode Y…
Event Description:
SRB EXPLOSION
SRB EXPLOSION CAUSES
EXTERNAL TANK EXPLOSION
HOT GAS PLUME CAUSES
EXTERNAL TANK EXPLOSION
Event Probability: 10% 100% 50% End State Abort Risk
Failure Mode X Y Y Pf = 94% 9.40E-02
N Pf = 5% 0.00E+00
N Y Pf = 79% 3.60E-01
N Pf = 0.1% 4.50E-02
Event Description:
SRB EXPLOSION
SRB EXPLOSION CAUSES
EXTERNAL TANK EXPLOSION
HOT GAS PLUME CAUSES
EXTERNAL TANK EXPLOSION
Event Probability: 0% - 20% 100% 35% - 65%
Failure Mode Y Y Y SRB and ET Explode
N Only SRB Explodes
N Y Only ET Explodes
N Nominal Abort
Identify the Sources of Risk & Uncertainty
SDV DARE Example Results
CV Stabilization FailureRecovery Failure
Landing Failure
Landing Sys. Failure
Failure Detection Failure
CV Separation Failure
Abort Pivotal Events
LOC
Ascent Time = 80 secondsRSRM Propellant FailureSide-Mount Vehicle
1
1/100,000
1/10,000
1/1,000
1/1001/100
1/10
1/1,000,000
Mean Value
5th Percentile
95th Percentile
Key
Mean Value
5th Percentile
95th Percentile
Key
Landing and recovery modules currently contain static placeholder values
SDV DARE Example Results
CV Stabilization FailureRecovery Failure
Landing Failure
Landing Sys. Failure
Failure Detection Failure
CV Separation Failure
Abort Pivotal Events
LOC
Ascent Time = 80 secondsRSRM Propellant FailureSide-Mount Vehicle
1
1/100,000
1/10,000
1/1,000
1/1001/100
1/10
1/1,000,000
Mean Value
5th Percentile
95th Percentile
Key
Mean Value
5th Percentile
95th Percentile
KeySDV DARE Example Results
CV Stabilization FailureRecovery Failure
Landing Failure
Landing Sys. Failure
Failure Detection Failure
CV Separation Failure
Abort Pivotal Events
LOC
Ascent Time = 80 secondsRSRM Propellant FailureSide-Mount Vehicle
1
1/100,000
1/10,000
1/1,000
1/1001/100
1/10
1/1,000,000
Mean Value
5th Percentile
95th Percentile
Key
Mean Value
5th Percentile
95th Percentile
Key
Landing and recovery modules currently contain static placeholder values
Pivotal Event W…
…Mitigate propagatio
n to system X
…Increase detection lead time
…Focus analysis on
event Z
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Risk Informed Abort Development
What are the significantabort-initiating failures?
Failure Mode N
Failure Mode 2
Failure Mode 1
…
Prioritized Initiators
Failure Mode 2
When can Failure Mode 1
occur?
AbortInitial Conditions
Locations
Trajectories
Damage States
Accident Progression
Phenomenological Modeling
Probabilistic Risk Assessment
What are theabort options?
Abort Design
Abort Mode 1,1
Abort Mode 1,2
Abort Mode 1,M
…
How effective is the abort?
Abort Risk Assessment
Iterate
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Conclusions• DARE is a proven, effective tool-based process
for evaluating abort effectiveness• DARE is designed to capture the best data and
models available throughout NASA• DARE supports risk informed decision making
throughout all stages of program development– Conceptual– Preliminary design– Testing and evaluation– Operations
• The dynamic DARE framework supports rapid analysis of system and operational trades
• DARE is a living process that will remain current and productive throughout Constellation life
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