I have to say that I found the mere fact that the NASA OIG had to be the whistleblower regarding the Artemis I damage really disturbing. It suggested another failure of NASA’s safety culture. I hope the crew survive their flight but it won’t surprise me if they don’t.
Quote from: Bob Shaw on 01/24/2026 01:40 pmI have to say that I found the mere fact that the NASA OIG had to be the whistleblower regarding the Artemis I damage really disturbing. It suggested another failure of NASA’s safety culture. I hope the crew survive their flight but it won’t surprise me if they don’t.LoC would surprise me. I guess it is less than 5% no matter how you calculate it. If they fly I hope they will have a fully successful mission, and if not fully successful I really hope they survive unharmed.For me, the real question is how NASA calculated LoC. They are clearly depending on models and small-scale experiments, and it is hard to avoid the feeling that the cost of another uncrewed flight test was a big factor in the decision of which factors went into the LoC computation. Is pLoC really below NASA's threshold of 1/270 (0.4%)?
Quote from: DanClemmensen on 01/24/2026 02:21 pmQuote from: Bob Shaw on 01/24/2026 01:40 pmI have to say that I found the mere fact that the NASA OIG had to be the whistleblower regarding the Artemis I damage really disturbing. It suggested another failure of NASA’s safety culture. I hope the crew survive their flight but it won’t surprise me if they don’t.LoC would surprise me. I guess it is less than 5% no matter how you calculate it. If they fly I hope they will have a fully successful mission, and if not fully successful I really hope they survive unharmed.For me, the real question is how NASA calculated LoC. They are clearly depending on models and small-scale experiments, and it is hard to avoid the feeling that the cost of another uncrewed flight test was a big factor in the decision of which factors went into the LoC computation. Is pLoC really below NASA's threshold of 1/270 (0.4%)?5% is 1:20, right? So more than 10x more risk of loosing live compared to the LOC of Commercial Crew 1:270. We have discussed this numbers extensively in the past e.g. here in SLS General Discussion Thread 7 or Re: Ares/Orion LOC/LOM Numbers?.
also? Does the performance of the cargo dragons also count in this calculation / improve the statistical accuracy?
theresacross@theresacross_Some context on the Artemis II heat shield conversation, since this is getting a lot of attention:A number of headlines frame this as “breaking news” or a reckless choice, which isn’t really accurate when you look at how these decisions are made in practice.First, adjusting re-entry trajectories to manage thermal loads is not new, unusual, or improvised. Re-entry profiles are always selected to balance heating, deceleration, and structural margins based on the specific spacecraft and mission profile. Apollo did this for lunar return velocities, the Space Shuttle’s entire TPS design was built around a specific entry corridor, and vehicles like Soyuz have long relied on multiple entry modes (including ballistic entries) that intentionally change thermal and g-loading conditions to stay within system limits. In other words, the trajectory is a controllable variable, and engineers routinely use it to protect hardware.Second, the Orion heat shield behavior seen on Artemis I wasn’t a surprise discovery that popped up overnight. NASA spent a long time analyzing the post-flight data, running new ground tests, and refining thermal and material models to understand exactly what happened. The issue was traced to how gases behaved within the Avcoat material under certain heating conditions, leading to localized char loss that looked visually concerning but remained within structural and thermal safety margins. This wasn’t hand-waving — it was a multi-year, data-driven investigation with internal and external technical review.At that point, there were essentially two options: redesign or rebuild the heat shield (which would have meant retooling, retesting, and likely years of delay), or adjust the re-entry profile so the vehicle stays within a thermal regime that is already well-characterized and understood. NASA chose the second option for Artemis II, which is a very standard engineering mitigation when the system behavior is understood and the environment can be modified in a controlled way.It’s also worth remembering that Artemis II is a test flight with crew — not a lunar landing mission. Its purpose is to validate Orion’s systems with humans aboard before committing to later missions. Flying within known limits while collecting additional data is exactly how human spaceflight programs traditionally progress.None of this eliminates risk — spaceflight never does — but it’s not accurate to frame this as NASA “ignoring” a problem or rushing something unstudied into flight. This is a classic engineering trade: use hardware that is well understood, operate it within a revised envelope, and avoid introducing entirely new unknowns late in the program.So while the headlines make it sound dramatic, the underlying decision-making is very much in line with how crewed spacecraft have always been flown.Just wanted to add that perspective to the discussion.@theresacross_ for K2 Studios LA
Re-entry profiles are always selected to balance heating, deceleration, and structural margins based on the specific spacecraft and mission profile.
At that point, there were essentially two options: redesign or rebuild the heat shield (which would have meant retooling, retesting, and likely years of delay),
NASA chose the second option for Artemis II, which is a very standard engineering mitigation when the system behavior is understood and the environment can be modified in a controlled way.
It’s also worth remembering that Artemis II is a test flight with crew — not a lunar landing mission. Its purpose is to validate Orion’s systems with humans aboard before committing to later missions.
This is a classic engineering trade: use hardware that is well understood, operate it within a revised envelope, and avoid introducing entirely new unknowns late in the program.
Artemis 2 Orion Heat Shield - Is It safe?QuoteFeb 9, 2026NASA had heat shield on the Orion capsule with Artemis 1, and they are flying the same heat shield design with astronauts on Artemis 2.
Feb 9, 2026NASA had heat shield on the Orion capsule with Artemis 1, and they are flying the same heat shield design with astronauts on Artemis 2.
I don't find that argument too convincing, and still coming down to whether you choose to trust NASA's analysis.
Quote from: Mythundare on 01/26/2026 06:00 pmI don't find that argument too convincing, and still coming down to whether you choose to trust NASA's analysis.It shouldn’t come down to analysis alone. There should be an opportunity to fly the new trajectory unmanned. (Or fly the third AVCOAT reformulation unmanned if that’s the route they went.) Orion/SLS production and operation should be rapid, responsive, and affordable enough to insert another unmanned test flight without derailing the schedule and the program. Heck, Orion’s unflown life support systems and blinkered power systems arguably need another unmanned flight test anyway.But Orion/SLS production and operation is not rapid, responsive, and affordable. It’s about as slow, unresponsive, and expensive as possible. So there’s no way to insert an unmanned test flight. So NASA has to risk astronauts on a flight that would be unmanned in a normal manned aerospace development and test program. Test as you fly and fly as you test is flight safety maxim. But Orion has to fly with astronauts as it has never been flight tested. That big picture program formulation failing alone should have disqualified the program and forced its termination years ago. It won’t. Too many jobs and too many votes in too many congressional districts. But it should.FWIW...
The link below is to an outline of a paper I am writing which will show the relationship between the "Artemis II Launch Decision" and "The Challenger Launch Decision" (book by noted sociologist Diane Vaughan). Diane's famous work was used by the Columbia Accident Investigation Board (CAIB) to prove that the exact behaviors which caused Columbia, existed 17 years earlier and caused Challenger. It is now 23 years post Columbia and we are proceeding down exactly the same path with the same toxic culture that caused two prior accidents.Wake up Jared Isaacman! Wake up NASA!hashtag#NASA hashtag#Challenger hashtag#ArtemisII hashtag#artemisIIheatshield hashtag#SRBORinghttps://lnkd.in/d5VAKqUF
From Challenger to Artemis II – When Screening Models Become Flight RationalePurposeThis document 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 PrecedentThe Mark Salita ModelThe 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 for flight rationaleWhat the Model Could Not PredictThe 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 couplingThese effects were explicitly outside the model’s scope.The model did not fail numerically, it failed epistemologically.The Artemis II ParallelThe 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.The Failure Mechanism It Cannot PredictArtemis I heatshield damage involved discrete structural spallation, pressure-driven failure, and large-area material lossAs 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 PatternA screening model was elevated beyond its design intent Missing physics was treated as uncertainty rather than invalidityProbabilistic arguments substituted for physical understandingConsensus replaced predictive capabilitySchedule pressure discouraged reframing the problemIn Challenger, the result was loss of vehicle and crew.Why Monte Carlo Amplifies the ProblemMonte 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 EchoIn 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 ObservationThe Challenger accident was not caused by O-rings alone. It was caused by mistaking analytical adequacy for physical understanding. The solution was the structural redesign of the SRB field joint and 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.The Artemis II heatshield decision risks repeating this exact error.History does not repeat because engineers forget equations. It repeats because organizations forget how to listen to them.
ex-nasa astronaut charlie camarda had a new post on his linkedin page about the upcoming sls/orion launch, with a link to a outline of a paper he is writing, about the resemblance between the analysis done before the challenger shuttle accident and now the orion heatshield analysis.[snippet of] outline of the paperQuoteThis document 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 Common PatternA screening model was elevated beyond its design intent Missing physics was treated as uncertainty rather than invalidityProbabilistic arguments substituted for physical understandingConsensus replaced predictive capabilitySchedule pressure discouraged reframing the problemIn Challenger, the result was loss of vehicle and crew.
This document 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 Common PatternA screening model was elevated beyond its design intent Missing physics was treated as uncertainty rather than invalidityProbabilistic arguments substituted for physical understandingConsensus replaced predictive capabilitySchedule pressure discouraged reframing the problemIn Challenger, the result was loss of vehicle and crew.
Quote from: DanClemmensen on 02/20/2026 01:03 amMy biggest and most urgent problem with what we heard at the press conference is NASA's refusal to immediately apply the applicable recommendations to the Artemis II mission in general, and specifically to the Orion heat shield. NASA claims that the entire report is inapplicable because Artemis does not use the same contracting mechanism as CCP. This is ludicrous.It's a little bit more than a different contracting mechanism. Starliner was designed by Boeing. SLS was design by NASA Marshall, and Orion by NASA Johnson. So for example, NASA knows that (unlike Starliner) Orion has all the redundancies it's supposed to, because they put in those redundancies while they were internally designing those systems themselves.
My biggest and most urgent problem with what we heard at the press conference is NASA's refusal to immediately apply the applicable recommendations to the Artemis II mission in general, and specifically to the Orion heat shield. NASA claims that the entire report is inapplicable because Artemis does not use the same contracting mechanism as CCP. This is ludicrous.
Some additional comments to the heat shield discussion.Quotetheresacross@theresacross_<snip>(...) leading to localized char loss (...)@theresacross_ for K2 Studios LA
theresacross@theresacross_<snip>(...) leading to localized char loss (...)@theresacross_ for K2 Studios LA
This article is a great piece of fiction. What this article does not say is that the Artemis Tiger Team’s analysis tools are so crude they cannot predict the structural failure of the heat shield and they only look at the thermal load on small flat arcjet test specimens. That material properties and permeability vary by orders of magnitude within single blocks of AVCOAT and that they lost about 40% of large pieces of char during the first heat pulse. We can expect to lose large pieces during the modified trajectory!If your analysis cannot predict the failure mechanism, spallation; you cannot use Monte-Carlo analysis to predict failures accurately and you cannot assume “operational work arounds” like changing the trajectory will mitigate failures!We learned this the hard way during Challenger, yet we use the same flawed safety cons and a one-sided flight rationale process to fool the public while playing Russian Roulette with Astronaut lives. Shame on NASA, we will lose our dominance in space if we do not raise the research bar at NASA!https://lnkd.in/exyUbc8E
Michael "Mike" Honisch • 3rd+To see what will really happen, you need to model reality...
Joseph A. Sholtis, Jr. Michael "Mike" Honisch. Yes....and you need to benchmark the models with representative test data.
Charles Camarda PhD AuthorJoseph A. Sholtis, Jr. We have to ask NASA to see the test data which validates their analysis can predict the location and extent of cracking, crack growth, and eventuak spallation. You will not get a response, because there is no analysis/test validation. Apollo engineers are rolling over in their graves.
Don Bingaman • 3rd+Why not go back to the non-propagating failure, continuous AvCoat/ Honeycomb matrix heat shield that brought 100% of the Apollo capsules back intact ? My understanding is that the new tiled heat shield approach is full of design uncertainties, allows hot gas build-up behind the tiles and showed a lot of spalling and "chunking out" not seen in any of the Apollo heat shields. Different is not better. I do not understand why we are re-inventing something that wasn't broken in the first place..
Charles Camarda PhD AuthorDon Bingaman exactly.
Jim Duffy • 3rd+We had to heat (bake) the Shuttle OMS pods on the launch pad for days before launch to get moisture out of the composite honeycomb structure skin panels. Moisture gets in these materials down there at KSC (duh !) but freezes and then cannot get out up in space. When the entry heating arrives the moisture (water) boils and you get the spallation. Moisture in TPS materials and even structures is not a new phenomenon and can be addressed.
Charles Camarda PhD AuthorJim Duffy tell that to the Artemis Program Manager and Chief Engineer!
