Artemis II Heatshield Concerns.docx

Artemis II Heatshield Concerns

Thoughts following the Jan. 8th NASA Headquarters meeting concerning the Artemis II Heatshield

I was invited to NASA HQ On Jan. 8th to attend a special meeting to address, I thought, the technical issues with the Orion heatshield. Orion is the Artemis Program’s Apollo-like capsule on steroids which is to lap the Moon much like Apollo 8 in 1968. Instead, what I walked into was a meeting intended to show NASA’s transparency in providing a summary of the analysis and test data used to validate flying the Artemis II mission with a crew.

Jared Isaacman, the new NASA Administrator, read my book. I thought he wanted to hear my ideas on how to fix NASA.  Instead, the meeting started with his declaration that the decision was final. We would launch Artemis II with a crew, even though the uncrewed Artemis I mission around the Moon returned with a seriously damaged heat shield, a failure in my opinion. I was not going to be allowed to present my position on why the decision was flawed.  Instead, the public would hear, through the two reporters allowed to attend, the Artemis Program narrative, only one side of the story. They would be bombarded with technical information which they would have very little time to understand, which would confirm the design change the Program made in 2016 to transition from an AVCOAT-filled honeycomb heatshield to a block AVCOAT tiled approach.

The Artemis Program Tiger Team’s Crack Indicator Tool (CIT) is woefully inadequate and incapable of predicting AVCOAT spallation (a structural failure and not a material failure) and even the multi-physics analysis, developed by a retired LaRC researcher whom I requested attend the meeting, could not predict spallation. Jared and the rest of the team at the meeting never even listened to his words or allowed the NESC to present their results. They just stacked the deck, pitched the same tired program narrative and made sure “journalists” were present to regurgitate the Artemis Program party line in the media in the days to follow.

Jared could claim transparency because the only thermal protection expert and public dissenter, me, was present. The new NASA Administrator was going to change things at NASA by supposedly opening up the doors and allowing transparency.

I was allowed only one-day to review some of the technical documents which were not open to the public and which were classified Controlled Unclassified Information/International Traffic and Arms Regulations (CUI/ITAR) prior to the Jan.8th meeting. Regardless of the constraints imposed, what I was able to learn in that very short time was appalling, much worse than I originally thought.

What I uncovered and can assert confidently is that:

1. NASA currently uses the same flawed thinking and crude analysis tools that caused both the Challenger and Columbia accidents. The analytical tools the Artemis Program engineers are using are woefully inadequate, use simple loosely-based physics, empirical relations, and may be classified as lumped-parameter methods; not full multi-physics analysis methods.

I was witnessing Einstein’s quote in full force; “The thinking which caused the problems we face, cannot generate the solutions we need.”

 It was apparent, we had learned nothing post Columbia!

2. These simple tools cannot predict the failure mechanism of Artemis I’s flight-test failure (char spallation, a structural failure and not a material or ablation failure as previously espoused by Howard Hu, the Artemis Program Manager).  This was eerily similar to the Mark Salita tool that could not predict the true failure mechanism for the Challenger accident (it was not the O-Rings as most of these engineers and the world would have thought),
3. The same bad behaviors and even some of the very same people that misrepresented the capabilities of their analytical tools during and after Columbia, were now going the next step and boasting to Jared that they could bound the problem and that their answers were “conservative” (claims patently false and similar to what caused both Shuttle accidents; in addition to their failed attempts to dismiss the reinforced carbon-carbon (RCC) panel 8R wing leading edge anomaly post my mission, STS-114 following Columbia,
4. It was obvious at that meeting that the human space program has lost all research capability. There was only one retired NASA researcher, the one I brought to the meeting for Jared to hear from, who volunteered to create the only full multi-physics-based analysis. Even this analysis, by his own admission, was not capable of predicting spallation.  I was never quite certain if the Artemis Tiger Team, the NASA Engineering and Safety Center (NESC) or the Independent Review Team (IRT) understood what I meant by a full multi-physics analysis or if they were afraid to speak up, and
5. The Artemis program has been severely mismanaged and has made so many glaring missteps and bad engineering and technology development decisions that it makes a person wonder about the quality of the training programs that are currently being used to develop Program Managers, Chief Engineers, and Systems Engineers at NASA?

Below are some of the glaring misrepresentations and contradictions that I was able to catch with only one day to review hundreds of technical pages and almost 8 documents (I never received any documents related to the Artemis Tiger Team data and/or analysis except for the actual presentation they presented):

1. The Apollo Engineers in the 1960’s understood that Block AVCOAT would crack.  That was why they decided to go with an AVCOAT-filled Honeycomb (H/C) design.  They knew how difficult it would be to certify the cracks would not grow and cause a structural failure, so they obviated that failure mechanism with the filled H/C design where the honeycomb cell walls would act as natural crack arrests.  They also realized the importance of permeability in relieving trapped gases. They were excellent engineers and still retained some of their research DNA from their NACA roots.

Apparently, the Lockheed and NASA engineers trying to reconstruct the AVCOAT material and AVCOAT-filled H/C concept did not find this out till much later in their AVCOAT development program.  A huge technical and managerial oversight! Yet we have proof that they experienced cracking and even spallation prior to Artemis I

2. Artemis Program engineers had experienced cracking and spallation in the first LEAF teat in the Ames arcjet in 2019 but dismissed it! I discovered this figure buried in the IRT report I was allowed to view one day prior to the meeting (The IRT final report was almost entirely redacted and hence prevented the public from knowing the embarrassing mistakes made by the program).  

They had no intention of showing this figure (figure 9 of the IRT report) at the Jan. 8th meeting and when I requested that they show it to Jared Isaacman, spallation during arcjet test was quickly dismissed as easy to overlook. The Associate Administrator, Amit Kshatriya quickly chimed in, “Hindsight is 20/20.”  Not really, this is the difference in how a “research engineer” conducts experiments compared to how the Artemis Program engineers conduct experiments when they are only looking for confirming cues and not looking at the test outliers and anomalies to understand real failure mechanisms! I truly believe if I was able to review the raw data from the entire Artemis Program, I would have uncovered several instances of cracking in the pyrolysis/char layers and even in the virgin AVCOAT prior to Artemis I.

3. Another chart which the Artemis Tiger Team did not intend to show on Jan. 8th, was the figure showing the spallation events as a function of time during the skip entry heating profiles (Figure 6.0-4 of NESC Report TI-23-0189 Vol. 1). In this figure, it was quite clear that the Program narrative they were feeding to the press, that it was the dwell time during the skip which allowed the gases generated to build up and cause the delta pressures which caused most of the spallation was, again, patently false.  In fact, during the first heat pulse (t ≈ 0 to 240 sec), approximately 40-45% of all the medium to large chunks of ablator spalled off the Artemis I heatshield.

Hence, varying the trajectory would do little to prevent spallation during Artemis II. I was never shown the new, modified trajectory at the Jan. 8th meeting.

4. Other figures which the Artemis Program Tiger Team did not show during the Jan. 8th meeting were the material property tests which showed huge variations in material properties and permeability as discussed below.  This would make the calculations for delta pressure and ultimate loads for calculating stresses and strains to identify crack initiation impossible and/or very difficult at best.

I will now address the technical issues with understanding the root cause and “failure mechanism” of the Artemis II structural heatshield failure and spallation.

Flawed Thinking and Crude/Inadequate Analysis Used to Assess Artemis I heatshield structural failure/spallation:

The Crack Indicator Tool (CIT) inadequacies:

The Crack Indicator Tool (CIT) is a lumped-parameter, physics-informed empirical screening model calibrated to coupon-scale test data 4” to 6”. It supposedly identifies conditions of concern and is not capable of a system response. This means it cannot address full-scale heatshield behavior or performance.

There is no coupling between the aerothermal heating, the thermal response, the gas generation, permeability and delta pressure changes; and crack initiation let alone crack propagation, and it uses very simplistic assumptions.  

This analysis provides a first-order screening assessment of crack initiation potential and is not intended to capture the coupled structural dynamics, crack growth, or system-level response.  It cannot predict crack growth and/or structural failures like spallation in even arcjet specimens, let alone the thermal-structural failures seen on the 16.5-foot Artemis I heatshield post-Earth entry! 

1. Because the elastic modulus of the material varies by orders of magnitude, it is impossible to accurately predict crack size and depth in the three varying layers of the heatshield (Char layer – pyrolysis layer – virgin AVCOAT layer) where the fracture behavior transitions from a porous/brittle material (Char) to a viscoelastic material (Pyrolysis layer), to the quasi ductile material (virgin AVCOAT)!

1. Elastic modulus: 1-2 orders of magnitude variation
2. Strength: greater than one order of magnitude variation
3. Thermal conductivity 5 times variation
4. Density: 2-3 times variation
5. Permeability: 103 to 104 times variation
6. Material Constitutive behavior: elastic→viscoelastic→granular

2. In order to predict pressure-driven cracking you have to understand the gas generation and the delta pressure created due to the direct relationship with the permeability of the porous material. The permeability of AVCOAT varies by three to four orders-of-magnitude spatially and temporally within any one block of the material and, hence, accurately predicting delta pressure to predict crack initiation is almost impossible.

3. Ablation is a transient problem where boundaries between layers are moving, properties depend on thermal histories not just temperature, cracking feeds permeability, permeability feeds pressure and pressure feeds cracking.  The CIT tool simplifies this very dynamic process with quasi-static, simplifying assumptions. Hence:

7. Crack initiation location is uncertain
8. Delta-P predictions are wildly sensitive
9. Local arcjet tests cannot scale to full heatshield behavior
10. Lumped 1-D tools (CIT-style) are inadequate

4. Hygrothermal cracks were seen deep in the virgin AVCOAT at low temperatures (~400 F) due to water adsorption. This phenomenon was not discussed or addressed on the Jan. 8th meeting. This is a hidden variable that was not represented in the model (moisture content). This is a big deal for Artemis because of:

1. Long pad times
2. Rollout humidity
3. Tanking cycles
4. Cold soak conditions
5. Freeze-thaw cycles (several of which occurred during pad stay prior to recent rollback due to helium leaks)

5. Hygrothermal cracking is a big deal for virgin AVCOAT

1. Moisture induced strain can be ~0.2 - 1% volumetric strain locally – that is huge for a brittle, low strength polymer composite
2. Constrained AVCOAT blocks lock in tensile stresses prior to flight
3. This can produce deep opening mode (Mode I) cracks
4. Hygrothermal cycling on the pad makes things worse
5. Cracks can penetrate inches deep prior to launch

1. This is dangerous because:

1. Early pyrolysis gas channeling
2. Accelerated pyrolysis front
3. Bondline vulnerability
4. Early spallation trigger

6. Freeze-thaw cycles on the pad can exacerbate pre-existing hygrothermal cracks

Inspection techniques could have easily missed in-plane microcracking in the virgin AVCOAT near resin rich areas.

6. The CIT tool only looks at one simplistic load case – the 1-D heating of a small, flat, material-like specimen/problem. The tool cannot address other loads which can cause thermal-structural failure in a full-scale heat shield such as:

1. Hygro-thermo-elastic cracking due to water desorption
2. Coupled loading
3. Aero pressure and shear loads
4. Fluctuating aeroacoustic loads, buffeting, etc.
5. Structural dynamic and vibration loads
6. Thermal stresses due to nonlinear temperature fields and curvature
7. Etc.

Bottom Line, the CIT tool fails the Feynman test: “If your explanation requires you to ignore a known mechanism (like spallation or hygrothermal cracking), you do not understand the problem.”

The CIT tool looks at a very local simplified part of the problem it cannot claim to bound “The Problem” and it definitely cannot claim to be “conservative.” It can only claim to ”bound” a problem.

The Hidden Assumption exposed for the CIT:

        The conservatism claim for the CIT explicitly assumes:

Thermal loading is the dominant and effectively the only load that matters for crack initiation.

This assumption may only be defensible for:

1. Small, flat arcjet specimens
2. Highly constrained laboratory boundary conditions
3. Quasi-static environments

This logic is not defensible for a 16.5 ft.-diameter curved flight structure experiencing multiple pressure, mechanical, acoustic, and vibration loading conditions!

Dysfunctional Culture and Flawed Organizational Behaviors Reminiscent of Challenger and Columbia:

1. Denying the criticality of a problem, restricting information flow, and denying access (transparency):

1. Immediately following the splashdown of Artemis I and once the Artemis Program realized the severity of the heatshield damage, they restricted the media to take photographs and publish the results (verified by onsite witnesses). The Program Office typically circles the wagons, prevents leaks to the press, and controls the narrative. We witnessed this post Columbia within the Shuttle Program Office, Mission Operations Directorate and Engineering Directorate at JSC.  
2. Immediately release a public statement minimizing the damage and creating the illusion the Artemis Program has the problem is “well in hand”

1. "Some of the expected char material that we would expect coming back home ablated away differently than what our computer models and what our ground testing predicted," "We had more liberation of the charred material during reentry than we had expected." and "We have a significant amount of margin leftover" (Program Manager Howard Hu, media briefing March 7,2023)

This was not “ablation” and you cannot say you have margin if you do not understand the failure mechanism (e.g., depending on the size, location, and time of Char loss, a breach of the Orion capsule could have occurred)!

3. NASA Press releases inaccurate statements to infer they have a good understanding of the problem, like they understand the ”root cause” of spallation seen on Artemis I. The flakes of AVCOAT which came off in 4”-6” flat arcjet specimens was not representative of the large structural ablator failures seen on Artemis I.

4. NASA creates an “internal” tiger team, prevents information from leaking even to key engineers within NASA, and classifies all data and reports CUI/ITAR restricted!

1. In June 2023, I was personally prevented from assisting and not allowed to form a truly independent external tiger team with experts from academia, Sandia, and other government agencies.
2. Another key thermal protection system (TPS) expert, Dr. Dan Rasky (developer of the PICA/PICA-X ablation system) was prevented from joining any teams.

5. You have members sign NDA-like agreements which force secrecy and pressure employees not to divulge the technical data or details with people outside the “Program”

2. NASA chooses to work the problem internally with JSC and Artemis Program engineers and the usual contractor and subcontractor teams

1. Similar to Columbia, JSC refused to seek help from external experts like the impact experts at NASA LaRC and GRC and other National Labs like Sandia. Instead, they relied on the crude and inadequate tool called CRATER which was never designed to predict damage and was misused by extrapolating over 6,000 times in size of ET foam!!!
2. Not one email left JSC asking for engineering help from the impact experts at NASA Langley Research Center (LaRC) or Glenn Research Center (GRC).
3. The Artemis team rejected pleas to seek help to understand Artemis I failure by using external teams by this author as early as June 2023.

3. Creating a non-psychologically-safe environment

1. The above actions create a psychologically unsafe environment where employees feel unsafe to take interpersonal risks like speaking out against the “Artemis Program” for fear of retribution.
2. When I started posting issues with the Artemis heatshield online, the lead for the Artemis NESC team was expressing concern to his teammates that “someone” was leaking information publicly!  This created additional pressure and fear within the rank and file of the NESC team.
3. NASA employees, contractors (e.g., Lockheed), and sub-contractors (e.g., Kratos) are afraid to speak out publicly and contradict the Artemis Program party line.  Even Dr. Dan Rasky, a long time NASA employee and technical manager of the Thermal Protection Systems Branch would only come forward and speak on live TV (ABC, GMA and Prime Time Live, 1/30/2026) once he was fully retired from NASA (Dec.31st, 2025)!
4. Jeremy Vander Kam, the prior TPS lead for the Orion heatshield, refused to speak to CNN reporters without approval from NASA HQ!
5. Even respected TPS ablative heatshield expert, Dan Rasky, would not speak to ABC interviewers with me until he was fully retired from NASA (Dan retired on Dec. 31, 2025, prior to the ABC interview with Elizabeth Schulze on Good Morning America).

4. When people get suspicious that NASA is hiding the severity of the problem, and after much pleading to do so, NASA creates an “Independent” Review Team (IRT) and stacks it with known “friends of the program”, NASA employees, ex-employees with ties to NASA (ASAP and/or NAC members), etc.

1. Charles Camarda had raised issues with the severity of the heatshield over 11 months prior to the actual photos being disclosed in the Office of the Inspector General (OIG) Report (May 1, 2024)
2. NASA did not include members on the IRT that could conduct independent analysis and/or tests and do not provide any funding to actually accomplish independent critical review
3. NASA did not provide funding for even the NASA Engineering and Safety Center (NESC) to do any significant testing and analysis and/or investigate alternative ideas.
4. The IRT was basically force fed the Artemis Program narrative through a firehose, with little to no access to dissenting opinions or alternative theories and analyses

1. One member of the IRT said “he would not fly on Artemis II” early on.  However, as the process continued, he changed his mind.  This is often the case when overwhelmed with confirming cues and information and little access to dissent or alternate analyses and test.

5. The leader of the IRT told his team early on that there would have to be total agreement with the written report and that there would not be any dissenting opinions.
6. Almost the entire IRT final report was redacted, so the public had no access to any information regarding the Artemis II heatshield.  Same is true for the NESC reports (3 volumes).

5. Hold a “transparent” meeting with invited press to “vet” the Artemis II decision with one of the most public technical dissenters, me, in attendance (Jan 8th, 2026).

1. Control the one-sided narrative and bombard the attendees with the Artemis Program view

1. Do not allow dissenting voices to present at the meeting
2. Do not even allow the IRT or the NESC to present their findings

2. Rely on the attending journalists to regurgitate the party line and witness the overwhelming consensus of knowledgeable people

6. When all else fails and some of the folks still do not buy what is being sold, bring out the “Hail Mary” pass in desperation:

1. At the end of Jan. 8th meeting, the Artemis Program Tiger Team lead presented a “torch test” of the polymeric composite Orion base structure to which the heatshield is bonded to convince everyone in attendance that there was some level of “redundancy” in the design.

7. JSC Engineering has provided sustaining engineering for NASA space programs for over four decades. They are subservient to the program managers as discussed by Diane Vaughan7 and are rewarded when they can maintain schedule and budget (“production Pressure”)1

1. Some of the very same people that were misrepresenting the capabilities of the CIT Tool did not speak up during the Columbia accident (1200 Civil Servants and 2500 Contractors) and highlight the glaring inadequacy of the CRATER tool to predict impact damage while the STS-107 crew was on orbit.  The tool was an empirical relation of 50 very small pieces of ET foam (6,000 times smaller than the foam that struck Space Shuttle Discovery during launch of STS-107) as shown below:

2. Some of those very same people would later misrepresented other similar tools Post Columbia like the RCC panel 8R anomaly following STS-114)2,3.
3. Tools these engineers created and used for over 20 years, like the RCC Damage Growth Tool (RDGT) were proven to be nonconservative and could have caused a Shuttle tragedy had there been damage to the leading wing of Space Shuttle on orbit. Yet these same engineers touted the conservatism of their predictions at numerous FRRs to proceed with defective wing leading edges1-3!

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Artemis Program Management Mistakes:

1. Failure to identify criticality of cracking and structural failures of block AVCOAT:

1. Cracking in block AVCOAT had been mentioned and addressed by Apollo engineers in the 1960’s.  This was the reason for selecting the AVCOAT-filled honeycomb design for the Apollo Heatshield.
2. JSC engineers voiced criticism of switching from an AVCOAT-filled H/C concept after EFT-1’s successful LEO entry in Dec. 2014. Engineers filed a dissenting opinion to the Artemis Program. It was dismissed by Artemis Program leadership.
3. Artemis TPS Lead, Jeremy Vander Kam, identified issues with the Block AVCOAT decision in his presentation in 2015: https://www.youtube.com/watch?v=Q4qsEz9ILGc 
4. Jeremy describes how difficult it would be to ensure Block AVCOAT will never crack and thus reduce its criticality on the Likelihood-Consequence Risk Matrix:

2. Poor management decision to mature only one-design option, Block AVCOAT, and drop development/maturation of alternate concepts prior to eliminating all knowledge gaps with the  new design concept:

1. Typical NASA program missteps such as selecting only one “point-design” are common in most U.S.-led human space programs (e.g., Space Shuttle, CEV, SLS, etc.).  Instead of using a “Set-Based Design” philosophy, similar to Toyota and used in research-based rapid concept development programs like the R&D ET Foam Impact Analysis Team1,4,5.
2. Engineers should have known the glaring knowledge gaps with block AVCOAT design and continued to mature other options (e.g., AVCOAT-filled honeycomb, PICA, etc.) in parallel.

3. Poor quality control (QC) of AVCOAT Processing and failure to recognize the importance of AVCOAT permeability:

1. Processing of AVCOAT blocks was like a garage/hobby shop operation with very poor quality control and inspection of to maintain uniform material properties such as density, mechanical properties, permeability/porosity, etc.  
2. AVCOAT blocks had orders-of-magnitude property variation spatially/locally within individual blocks.  This resulted in the failures seen on Artemis I where permeability and delta-pressure buildup caused large chunks to spall.

4. Poor management decision to stack Orion capsule without first understanding the critical failure mechanism of the Artemis I heatshield

1. Artemis Program management decided to stack the Orion capsule at the Cape to the launch vehicle on October 19, 2025. They knew about the low permeability causing the pressure build up as early as October 2024.  The low permeability heatshield was already installed on the capsule well before December 2024. The program did not want to risk a schedule delay to remove the heat shield.
2. The current heatshield on Artemis II has a lower permeability than on Artemis I and, hence, is more prone to spallation. This is the worst possible case for an already defective heatshield.
3. The program decided it would mitigate the risk of spallation on Artemis II by changing the trajectory, even though they have no validated analysis technique that can predict spallation! Hence, there is no way to ensure the modified trajectory will indeed “mitigate” risk.

5. The Artemis Program never once attempted to develop a full Multiphysics analysis to predict spallation

1. Similar to Challenger and Columbia, the Program office never attempted to create an improved physics-based transient understanding of the failure mechanism which included crack propagation and spallation. It had four years to do so.  They also prevented others from developing an external team to do so.

Misuse of Monte-Carlo (MC) analyses to assist in providing flight rationale:

NASA typically uses or should I say misuses Monte-Carlo (MC) simulations to construct a risk framework which can be used to classify the uncertainty of a complex problem as “acceptable” risk.  NASA did not use MC or Probabilistic Risk Assessment (PRA) as a primary flight rationale tool during the Apollo Program.  During the Apollo Program, safety was argued by deterministic margins, worst-case bounding, test-to-failure, and design conservatism.  The key Apollo mindset was “If we can’t bound it physically, we don’t fly it.”

This mindset changed during the Shuttle era.  Shuttle was too complex to fully test.  NASA increasingly relied on PRA and MC.  Post Challenger, PRA became institutionalized but was not officially allowed to replace deterministic safety margins.  Post Columbia, NASA doubled down on PRA, and this is where probability crossed the line from supporting “insight” to decision authority! MC went from “how sensitive is my answer” to “why my answer is acceptable.”  It became a critical tool that Program Managers could use to “continue flying.”

The bottom line is that MC without predictive multi=physics damage modeling is not a safety tool. It cannot be accurate without multi-physics damage prediction!

You cannot use reduced order physics like 1-D thermal/ablation models, empirical recession rates and effective property averaging (virgin/char blends) to bound the AVCOAT ablation problem. AVCOAT has-orders-of magnitude permeability variation, nonlinear char morphology, and discrete cracking and void coalescence.  Perturbing inputs in a simplistic model does not preserve model validity.  The governing equations themselves change.  That is why a true, integrated multi-physics analysis is necessary.

1. Prior misuse of MC simulation during the Space Shuttle Program Post Columbia6:

The Space Shuttle Program was never able to validate multi-physics analysis to determine and predict ET foam shedding, yet it used MC to provide flight rational to continue flying with known debris threats post Columbia which resulted in two near misses:

1. Prior to STS-114, the crew requested removal of the Protuberance Air Load (PAL) Ramp, a large piece of ET foam.  MC estimated the probability of LOC of 1:10,000. On our mission the PAL ramp came off during launch and almost hit our port wing.  A near miss.
2. Prior to STS-121, MC estimated the LOC for Ice Frost Ramps (IFR) to be ~ 1:100.  IFRs were jettisoned on STS-121 just missing its port wing.  Another near miss!

NASA Human Space Programs continue to use Monte Carlo (MC) Simulation and Probabilistic Risk Assessment (PRA) as tools to support their risk construction and to develop flight rationale – this practice should be discontinued!

At the end of the Jan. 8th meeting, MC and the “torch test” of the Orion capsule composite structure were used as a “when all else fails” Hail Mary pass to prove some sort of worst-case/redundant capability! A clear sign of desperation.

From Challenger to Artemis II – When Screening Models Become Flight Rationale

Purpose

This section draws a direct technical and organizational parallel between the Mark Salita SRB joint leakage model used prior to the Challenger accident, and the Crack Indication Tool (CIT) and Monte Carlo (MC) simulations studies used to support Artemis II heatshield flight rationale.

The comparison is not rhetorical. It is structural, analytical, and behavioral.

The Challenger Precedent

The Mark Salita Model

The Mark Salita model was a lumped-parameter, empirically informed analytical tool which was designed to estimate O-ring erosion and blow-by likelihood  and was calibrated to limited test conditions.

Crucially, it:

- Did not model joint rotation

- Did not capture transient gap opening

 - Did not represent dynamic seal behavior.

Yet it was repeatedly presented as:

- Conservative

- Bounding and

 - Sufficient to help provide flight rationale

What the Model Could Not Predict

The Challenger SRB joint failure was governed by:

 - Dynamic joint rotation under load which showed gaps opening instead of closing - Transient loss of sealing pressure

 - Time-dependent thermal-mechanical coupling

These effects were explicitly outside the model’s scope.

The model did not fail numerically, it failed epistemologically.

The Artemis II Parallel

The Crack Indication Tool (CIT)

CIT is a coupon-scale, 1-D screening tool which is calibrated to small flat arcjet specimens and is intended to flag conditions of concern (e.g., the initiation of a crack).

It does not model crack propagation, permeability evolution, pressure-driven delamination or spallation; nor does it represent structural dynamics of a curved, full-scale heatshield. It also cannot predict early crack initiation in virgin AVCOAT due to water adsorption.

The Failure Mechanism It Cannot Predict

Artemis I heatshield damage involved discrete structural spallation, pressure-driven failure, and large-area material loss

As with the Salita model, the governing physics lie outside the model domain and, hence, conservatism claims are misrepresentations since they cannot address the true failure mechanism.

The Common Pattern

In both cases:

1. A screening model was elevated beyond its design intent
2. Missing physics was treated as uncertainty rather than invalidity
3. Probabilistic arguments substituted for physical understanding
4. Consensus replaced predictive capability
5. Schedule pressure discouraged reframing the problem

In Challenger, the result was loss of vehicle and crew. We are trying to prevent the loss of the Artemis II crew.

Why Monte Carlo Amplifies the Problem

Monte Carlo analysis assumes  a valid governing model and perturbations that do not change failure physics.

For the  AVCOAT heatshield, crack initiation changes permeability, permeability changes pressure, and pressure changes crack growth.

These feedbacks alter the governing equations similar to how the loading dynamics of the SRB joint enabled gaps in the field joint to open instead of close and hot gases to blow by the O-rings.

Monte Carlo dispersion of an invalid model produces false confidence, not safety.

The Cultural Echo

In both Challenger and Artemis, dissent existed but was marginalized, language shifted from physics to probability, leadership sought reassurance rather than understanding, and models became arguments rather than tools.

The most dangerous moment is when a model is said to be “conservative” without a mechanism to verify that claim.

Closing Observation

The Challenger accident was not caused by O-rings or temperature on the day of launch; it was caused by a deviant joint design which opened instead of closed when loaded. It was caused by mistaking analytical adequacy of a simplified test for physical understanding of the system. The solution, post Challenger, was the structural redesign of the SRB field joint and the use of the exact same O-rings.  The operational work-around of launching when temperatures were warm at the Cape post-Challenger was not a sufficient solution which could mitigate risk!  The same is true for the “modified entry trajectory” for Artemis II, it is not sufficient to assure risk is mitigated.

The Artemis II heatshield decision risks repeating this exact flawed analytical understanding and risk rationale.

History does not repeat because engineers forget equations. It repeats because organizations forget how to listen to them.

References

1. Camarda, Charles J.:  “Mission Out of Control – An Astronaut’s Odyssey to Fix High-Risk Organizations and Prevent Tragedy”. Headline Books Inc. 2025.

2. Camarda, Charles J.:  “Evaluation of RCC Damage Growth Tool (RDGT) with Respect to Claims of Conservatism. November 2007. https://drive.google.com/file/d/1rCL5Zw3ZxaLm3uBVnUsxm3WVkmkkavCm/view?usp=sharing 

3. Harris, Charlie: “Preliminary Findings:  Peer Review – Damage Growth Tool.” April 22, 2005 https://drive.google.com/file/d/1tmHhFKW0GHo5n2UPoCYDEZApciJuLXQE/view?usp=sharing

4. Camarda, Charles J.; Scotti, Stephen; Kunntu, Iivari; and Perttula, Antti: “Rapid product development methods in practice – case studies from industrial production and technology development.” Presented at the ISPIM Connects Ottawa, Ottawa, Canada, April 7-10, 2019. https://drive.google.com/file/d/1Jv2l7hElKm1auqvu7d_tqx97igNjcGFM/view?usp=sharing 

5. Camarda, Charles J.; Scotti, Stephen; Kunntu, Iivari; and Perttula, Antti: “Rapid Learning and Knowledge-Gap Closure During the Conceptual Design Phase – Rapid R&D.” Technology Innovation Management Review, March 2020 (Volume 10, Issue 3).https://drive.google.com/file/d/16UklMxL6Ov8dzDAntxPwmyMXlD9eFUEt/view?usp=sharing 

6. Camarda, Charles J.: “Failure is Not an Option... It’s a Requirement.” Presented at the 50th AIAA/ASME/AHS/ASC Structures, Structural Dynamics, and Materials Conference.” AIAA Paper Number 2009-2255. https://drive.google.com/file/d/1Zr6dKyEOodlmXLxLqT5otd_qWQpAqCLj/view?usp=sharing 

7. Vaughan, Diane:  “The Challenger Launch Decision – Risky Technology, Culture, and Deviance at NASA.” The University of Chicago Press, 1993.