First SLS/Orion manned mission faces new delays because of Orion heat shield issues
Damage to Orion heat shield caused during re-entry in 2022,
including “cavities resulting from the loss of large chunks”
Because the damage to the heat shield on the Orion capsule that flew around the Moon in late 2022 remains somewhat unexplained, NASA is considering delaying the next SLS/Orion mission, presently planned for September 2025 and intended to be the first Artemis flight to carry humans and take them around the Moon.
The heat shield, already installed at the base of the Orion spacecraft, will take the brunt of the heating when the capsule blazes through Earth’s atmosphere at the end of the 10-day mission. On the Artemis I test flight in late 2022, NASA sent an Orion spacecraft to the Moon and back without a crew aboard. The only significant blemish on the test flight was a finding that charred chunks of the heat shield unexpectedly stripped away from the capsule during reentry as temperatures increased to nearly 5,000° Fahrenheit (2,760° Celsius).
The spacecraft safely splashed down, and if any astronauts had been aboard, they would have been fine. However, the inspections of the recovered spacecraft showed divots of heat shield material were missing.
Two years later, despite extensive investigation and analysis, it appears NASA has not yet identified the root cause of the damage. The ablative material used on Orion was similar (though not identical) to the material used successfully on numerous other heat shields since the 1960s, yet it did not perform as expected.
NASA is presently facing three options. Do nothing and fly the next mission as planned, with four astronauts. It could rethink the trajectory used during re-entry, though this would likely not change things significantly unless the astronauts don’t go around the Moon as planned. Or it could change the heat shield itself.
The first two options are very risky, considering the unknowns. The latter involves a major delay of at least two years.
A decision must be made soon however. To meet the agency’s schedule it must begin stacking SLS’s two solid-fueled strap-on boosters next month. Those boosters have a limited life expectancy originally estimated to be one year. In the first unmanned Artemis test flight in 2022, NASA because of other delays stretched that life span to two years, and had no problems with the launch. If it stacks the boosters now and then has to delay for two more years to redesign Orion’s heat shield, those boosters will have been stacked for three years when launched.
Considering how seriously NASA is taking the issues with Starliner, which are likely not as serious as a heat shield that doesn’t work reliably, it would seem insane for NASA to launch Orion manned without fixing its own problem. And yet, for more than two decades NASA has consistently not demanded the same safety standards for SLS that it has demanded for the private commercial rocket startups. We shall see if this pattern now persists.
I continue to believe that the first Artemis lunar landing will not take place before 2030 (at least six years behind schedule). This heat shield dilemma only strengthens that prediction.
The support of my readers through the years has given me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Four years ago, just before the 2020 election I wrote that Joe Biden's mental health was suspect. Only in the past two weeks has the mainstream media decided to recognize that basic fact.
Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Even today NASA and Congress refuses to recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
Please consider supporting my work here at Behind the Black.
You can support me either by giving a one-time contribution or a regular subscription. There are five ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation:
5. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above. And if you buy the books through the ebookit links, I get a larger cut and I get it sooner.
Damage to Orion heat shield caused during re-entry in 2022,
including “cavities resulting from the loss of large chunks”
Because the damage to the heat shield on the Orion capsule that flew around the Moon in late 2022 remains somewhat unexplained, NASA is considering delaying the next SLS/Orion mission, presently planned for September 2025 and intended to be the first Artemis flight to carry humans and take them around the Moon.
The heat shield, already installed at the base of the Orion spacecraft, will take the brunt of the heating when the capsule blazes through Earth’s atmosphere at the end of the 10-day mission. On the Artemis I test flight in late 2022, NASA sent an Orion spacecraft to the Moon and back without a crew aboard. The only significant blemish on the test flight was a finding that charred chunks of the heat shield unexpectedly stripped away from the capsule during reentry as temperatures increased to nearly 5,000° Fahrenheit (2,760° Celsius).
The spacecraft safely splashed down, and if any astronauts had been aboard, they would have been fine. However, the inspections of the recovered spacecraft showed divots of heat shield material were missing.
Two years later, despite extensive investigation and analysis, it appears NASA has not yet identified the root cause of the damage. The ablative material used on Orion was similar (though not identical) to the material used successfully on numerous other heat shields since the 1960s, yet it did not perform as expected.
NASA is presently facing three options. Do nothing and fly the next mission as planned, with four astronauts. It could rethink the trajectory used during re-entry, though this would likely not change things significantly unless the astronauts don’t go around the Moon as planned. Or it could change the heat shield itself.
The first two options are very risky, considering the unknowns. The latter involves a major delay of at least two years.
A decision must be made soon however. To meet the agency’s schedule it must begin stacking SLS’s two solid-fueled strap-on boosters next month. Those boosters have a limited life expectancy originally estimated to be one year. In the first unmanned Artemis test flight in 2022, NASA because of other delays stretched that life span to two years, and had no problems with the launch. If it stacks the boosters now and then has to delay for two more years to redesign Orion’s heat shield, those boosters will have been stacked for three years when launched.
Considering how seriously NASA is taking the issues with Starliner, which are likely not as serious as a heat shield that doesn’t work reliably, it would seem insane for NASA to launch Orion manned without fixing its own problem. And yet, for more than two decades NASA has consistently not demanded the same safety standards for SLS that it has demanded for the private commercial rocket startups. We shall see if this pattern now persists.
I continue to believe that the first Artemis lunar landing will not take place before 2030 (at least six years behind schedule). This heat shield dilemma only strengthens that prediction.
The support of my readers through the years has given me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Four years ago, just before the 2020 election I wrote that Joe Biden's mental health was suspect. Only in the past two weeks has the mainstream media decided to recognize that basic fact.
Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Even today NASA and Congress refuses to recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
Please consider supporting my work here at Behind the Black.
You can support me either by giving a one-time contribution or a regular subscription. There are five ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation:
5. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above. And if you buy the books through the ebookit links, I get a larger cut and I get it sooner.
The first Orion, and previous uses of AVCOAT it was essentially poured into cells and glued to base to become the heat shield. This past flight that cast AVCOAT into blocks and then attached them to the base like the shuttle tiles. It sounds like Dragon does the same but uses another material called PICA-2.
Did NASA ever test this new design in an actual reentry before Artemis 1? I expect not. Sounds like they can’t figure out just why its not working like it should and how to stop it.
My suggestion would be to bite the bullet and get a new heat shield. Maybe the PICA stuff. If you won’t then cancel it because every entry will be dice roll.
Rocket J Squrrel: NASA never tested the Orion heat shield design in flight. The 2014 Orion test flight used a different heat shield design that NASA had already abandoned, before the flight. That mission was dishonestly touted as a test of Orion’s heat shield, and though most of the press pitched that lie, it still was a lie.
The 2022 flight provided the first test, and it proved the new design had its own problems. Two years later it appears NASA has done nothing to fix it. The agency should have taken action more than a year ago to replace this heat shield. It instead has dithered.
I am puzzled by the lack of any hypothetical discussion on the use of “active” heatsheilding, the use of rockets to slow reentry prior to or during atmospheric reentry.
Of course retro-rockets are commonly used to initiate atmospheric entry by lowering the perigee to the point where it intersects with a substantial density of atmosphere, but in these cases the atmosphere does the majority of the work of decelerating the vehicle, and that resultant heat energy is both dissipated into it and absorbed by the heat shield.
In contrast, I mean using retro-rockets to actually cancel a significant portion of the orbital velocity, to the point where the entry velocity generates a much more modest amount of heat. This would require extravagant amounts of fuel, but orbital refueling might make this feasible. It might thus be possible to convert lunar reentry conditions to LEO entry conditions, for example.
Ray Van Dune: The difference between a typical LEO re-entry and a lunar re-entry is quite significant. A typical Dragon re-entry is at a velocity of around 7.5km/sec. The Apollo missions had an average re-entry velocity of around 11km/sec. I seem to remember reading somewhere that the Artemis return will be even higher velocity.
So, to bring that kind of lunar re-entry velocity down to a normal LEO velocity, you’d be doing a burn for more dV than the TLI burn that sent you to the moon in the first place. Even assuming refueling at the moon, that still means you’re keeping the tankage and everything else required for a burn of that magnitude and duration, rather than discarding it after TLI. Even assuming you design the whole mission around Starship which should have that capability as it would be required for the nominal Mars mission, now you’re talking about building and supplying a fuel depot not just in LEO, but another one in Lunar orbit as well. Long term, yes, we should be doing that, but no way it fits into the Artemis program.
Note that the problems are all with Orion, not SLS. All elements of the SLS for Artemis II are at the Cape waiting for their payload.
They could send a trunk up adapted for the return deceleration.
Discard the old trunk in lunar orbit and attach the new return trunk. Without a capsule on the return trunk that weight could be turned into more fuel.
But I was just thinking. If we need a specific speed to escape the Earths gravity why would we need a higher speed to escape the smaller Moons gravity? Or is it that the Earth sucks the ship in faster over that return distance?
Either way or why it doesn’t matter. The next generation will be a mini shuttle type ship with the capacity to ‘skip’ into and out of the atmosphere in order to reduce speed over time and number of skips. Capsules can not do this well.
I never meant to suggest “super-retro” as a solution for Artemis, but as an advanced concept to be explored. That would be like “converting” an Atlas 5 to perform like a Falcon 9 – ain’t gonna happen.
Remember that only a decade or so ago, most every aerospace engineer would confidently tell us that orbital booster reuse was impossible, but even if technically doable, would certainly be economically pointless, and could dazzle us with the numbers that proved it!
”Remember that only a decade or so ago, most every aerospace engineer would confidently tell us that orbital booster reuse was impossible…”
No, we didn’t. It would be a silly thing for us to tell you considering that by a decade ago booster re-use had already been occurring for 33 years.
”…would certainly be economically pointless, and could dazzle us with the numbers that proved it!”
And it was pointless at low flight rates. Actually, it was worse than pointless. It was counterproductive. Like much of science, understanding the numbers helps one understand the underlying reality.
Mr. Z,
You could well prove to be right about the Artemis elements now part of the program of record – Orion in particular – not being ready before 2030. It could be even later than that.
While mkent is technically correct that the SLS componentry for the putative Artemis 3 mission will be ready to go long before that, absent a functional Orion, it would still be a case of SLS being all dressed up but its “prom date” proving to be a no-show. Or perhaps the analogy of SLS being a jilted groom and Orion being a runaway bride works better? Either way, a launcher that lacks a payload serves no purpose. Without Orion, SLS can’t even, in Block 1B trim, send any modules to Gateway.
In the meantime, of course, Starship development will continue at the maximum speed SpaceX can manage – and the U.S. Permit Wallah will allow. At some point on this development path, a version of Starship capable of launching with crew aboard and returning to Earth from orbit will exist and Jared Isaacman – plus selected others – will ride it. Beefing such a vessel up suitably to send crew to rendezvous with HLS in lunar orbit – maybe NRHO, maybe some nearer orbit – will follow quite quickly.
Jared will certainly be continuously “encouraging” SpaceX to achieve the crew-to-Earth-orbit-and-back goal as soon as possible and, one strongly suspects, the crew-to-cislunar-rendezvous-and-back version too. I think there is at least a lunar “Polaris 4” and even a Martian “Polaris 5” pair of notions that we will see revealed in the fullness of time.
Six more years is a long time in terms of Starship progress. Six years prior to the current date, for example, only sub-scale prototypes of the Raptor 1 engine tech existed and the decision to make Starship of stainless steel instead of carbon fiber composite had not yet been made.
I think Starships capable of crew launches from Earth are likely to exist as little as three years from now. If NASA and its legacy contractors are still futzing around with Orion such that Artemis 3 cannot launch before 2027 or 2028, I think there is a real possibility of Elon and Jared ninja-ing Artemis 3, especially if it looks as though the PRC might manage even a minimal flags-and-footprints mission before Artemis 3 can be pulled off in the fashion now contemplated. If Trump is President, I would anticipate no problem with his administration authorizing this “audible” at the line of scrimmage, so to speak.
If this happens, I would anticipate that SLS and Orion will be promptly cancelled and – thank goodness – four hapless astronauts will never be launched on the maiden voyage of the SLS Block 1B with the much-troubled and never-to-be-tested-unmanned EUS upper stage as part of Artemis 4.
Is there something like a 2025 Project for NASA? That is, should Mr. Trump regain the White House, what kind of process would be needed to bring some kind of order to the institutional chaos and ineptitude that is described in this post and others? In short, how do you “fix” NASA and the whole Artemis – SLS boondoggle?
A fine point, and perhaps a controversial one with respect to some perspectives, but without some kind of a *vision* of what kind of a space program we want to see happening within the jurisdiction of this country, how does anyone know what to “do” with respect to changing the way that things are now? Again, how can — and why should — NASA be fixed? I know, I know; “let the market do it, and don’t worry about having a plan,” but do we really want to go on squandering all those resources on non-performing programs like Artemis – SLS while the deficit / debt clock ticks over another trillion dollars?
(As a very imperfect analogy, and with explicit reference to competition with China, do we allow “the market” to determine the outcome of a war for national supremacy in space? That is, if China has a plan to essentially colonize the moon and the rest of the Solar System while Washington is asleep (if not paid off), do we want / need some kind of a national “plan” to compete with them and prevail? Just saying. Perhaps no one cares.)
Robert’s Capitalism in Space might be a good starting point, but what would be required to turn a position paper into a 2025-type action plan?
“No, we didn’t. It would be a silly thing for us to tell you considering that by a decade ago booster re-use had already been occurring for 33 years.”
Citation, please.
I’m sure he meant the Space Shuttle.
pzatchok asked: “If we need a specific speed to escape the Earths gravity why would we need a higher speed to escape the smaller Moons gravity? Or is it that the Earth sucks the ship in faster over that return distance?”
The latter is the case. It is a bit like dropping a rock; it picks up speed as it falls. Gravity is not as strong at the distance of the Moon (it is only responsible for keeping the Moon in orbit), so the acceleration toward the Earth is relatively small, but as the capsule comes closer to the Earth it accelerates faster, with modifications as it approaches the perigee somewhere inside the atmosphere.
“Either way or why it doesn’t matter. The next generation will be a mini shuttle type ship with the capacity to ‘skip’ into and out of the atmosphere in order to reduce speed over time and number of skips. Capsules can not do this well.”
Skipping “out of” the atmosphere (wherever “out” may be) may not be the answer. Once back out of the atmosphere, the mini shuttle will have to make a complete orbit of the Earth before beginning its deceleration again when it returns close to its perigee, 90 minutes or so later. One problem with approaching from infinity (the Moon is close to infinity, for purposes of escape velocity) is that the vehicle may have to curve around the Earth during its deceleration. If it does not slow enough, then the vehicle will not curve as fast as the atmosphere does and will end up back out of the atmosphere, which is not exactly skipping, the way a stone skips off water, but the effect is the same. A fast-moving reentry vehicle with some amount of lift could use some of that lift (upside down) to turn itself around the curve of the planet and remain within the atmosphere under conditions where it would normally skip back out. As far as I know, Apollo’s trajectory did not require this feature.
A few months ago, we here at BTB discussed Apollo’s reentry, in which the capsule “skipped” to a slightly higher altitude during reentry, but it remained deep enough inside the atmosphere to keep the deceleration quite high. My question is: dies it really constitute a “skip” if it doesn’t leave the atmosphere (again, wherever the “edge” is)?
_________________
Ray Van Dune wrote: “Remember that only a decade or so ago, most every aerospace engineer would confidently tell us that orbital booster reuse was impossible, but even if technically doable, would certainly be economically pointless, and could dazzle us with the numbers that proved it!”
Engineers didn’t consider recovery and reuse impossible, as it was done with the Space Shuttle’s Solid Rocket Boosters, but it was thought to be impractical and uneconomical, as demonstrated with their rather awkward recovery. Reusing the SRBs was about as expensive as making new ones, so reuse was pretty much a wash.
The whole Shuttle project convinced many that reuse of the Orbiter was also not practical,* which is one reason that Congress told NASA to revert to the expendability of Apollo type methods for SLS. NASA’s solution for Constellation similarly reverted to expendable flight hardware. Fortunately, Peter Diamandis, Blue Origin, and SpaceX believed that reusability could be made practical and economical, if only some innovation and creativity were applied. There was a time when NASA was trusted to be innovative and creative, but that institution has become too much of a Congressional political tool rather than the national asset that it once had seemed. Thank goodness that it is encouraging commercial space companies to take over the role of experimenting with invention and pioneering economical space projects. SpaceX is advancing revolutionary ideas on Starship that require a lot of development testing, rather than many of the other companies (e.g. Blue Origin and Rocket Lab) that are more evolutionary and don’t need as much testing of their own trailblazing ideas, which they hope will work on first launch.
SpaceX took a few tries to figure out the proper control of returning a booster, and then they landed them on rocking and rolling ocean barges. No wonder a couple of them fell off and into the ocean. The innovation, however, was reserving enough fuel to conduct a reentry burn (a form of propulsive reentry) that slowed the booster enough to avoid over-stressing the engines during reentry, then relighting one or three for the landing. Up to then, engineers concentrated on improving performance rather than cost.
__________________
Milt asked a slew of questions, but I will reply to two:
“In short, how [and why] do you ‘fix’ NASA and the whole Artemis – SLS boondoggle?”
Artemis was designed poorly and probably cannot be economically repaired. Throw it away and get a new one.
Government has its needs and We the People have our own. Why you fix NASA is so that the government has its own tool for solving its aeronautic and space problems. This is why NASA was formed in the first place. How to fix it is to remove the line items from NASA’s budget so that its scientists and engineers can work on Congress’s problems in an intelligent rather than a political fashion. This is unlikely to happen, because Congress’s problems are not technical but political. We the People’s problems are technical and financial, which are some of the strengths of free markets. NASA managed to eke out the Skylab project, whose purpose was technical, not political — good for them.
“As a very imperfect analogy, and with explicit reference to competition with China, do we allow ‘the market’ to determine the outcome of a war for national supremacy in space?”
Yes.
This was the irony of the Man In Space Soonest, Mercury,** Gemini, and Apollo projects. They were intended to win a space race to show the superiority of the free market capital economy over the top-down command economy, but instead of using free market capitalism, the government used command and control. It worked, because it was within a free market capitalistic economy, but “within” was not the point trying to be made.
Allowing free market capitalism to determine what we do in space not only is the fastest and most cost effective way to achieve a goal, but it allows for goals that benefit the population — all mankind, as the Outer Space Treaty says. It is the population that will buy the goods and services produced in space, and their demand will drive the direction of the development of those products. Resources are directed toward solving customer problems, and when We the People are the customer, they solve our problems. If the Moon is a reasonable goal, as determined by sales and profits (the reward for efficient use of resources), then commercial space companies will pursue it. If it is merely a prestige goal, then commercial space companies may choose to pursue it as a demonstration of superiority — just like the nations do — except the companies may be demonstrating technical and cost superiority rather than governance superiority. If a company can do what once took the resources of entire nations, then it must be the vendor of choice.
Right now, government is a major customer, and it demands certain products, such as launch services, transport of men and materiel to the ISS, and new space stations to replace the ISS in six years. ISS took fifteen years to start on orbit construction and another decade to complete the assembly and become officially operational. The government thinks that commercial companies can put up their first modules in half the time it took for ISS’s first module — and at far less than 10% of the cost.
__________________
* A small structure, such as an Apollo capsule, does not flex much, so a solid heat shield is possible. (Could it be that Orion is just large enough that it flexes just a little too much, explaining why its heat shield has some chunks of the heat shield unexpectedly strip away from the capsule during reentry? Probably not, because this didn’t happen during the 2014 test with the other heat shield material). The Space Shuttle started out as a small ship, around the size of the X-37, until NASA needed political support from the Air Force, who wanted a much larger ship for its own purposes. The large size resulted in a lot of flexing (have you ever watched a wing flex as you flew on a large commercial airliner?), so NASA solved the flexibility problem with tiles as a heat shield, but they turned out to be too fragile for the reality of Shuttle operations. SpaceX is now spending tens of millions of dollars trying to find a more robust tile system for its own oversized, flexible Starship.
** President Kennedy’s goal of putting a man on the Moon and returning him safely to Earth was the justification to continue with Project Mercury, because we sure did miss the goal of the MISS project.
I’m sorry but you assume a lot of things about this heat shield situation that are not actually true.
“NASA is presently facing three options. Do nothing and fly the next mission as planned, with four astronauts. It could rethink the trajectory used during re-entry, 𝐭𝐡𝐨𝐮𝐠𝐡 𝐭𝐡𝐢𝐬 𝐰𝐨𝐮𝐥𝐝 𝐥𝐢𝐤𝐞𝐥𝐲 𝐧𝐨𝐭 𝐜𝐡𝐚𝐧𝐠𝐞 𝐭𝐡𝐢𝐧𝐠𝐬 𝐬𝐢𝐠𝐧𝐢𝐟𝐢𝐜𝐚𝐧𝐭𝐥𝐲 𝐮𝐧𝐥𝐞𝐬𝐬 𝐭𝐡𝐞 𝐚𝐬𝐭𝐫𝐨𝐧𝐚𝐮𝐭𝐬 𝐝𝐨𝐧’𝐭 𝐠𝐨 𝐚𝐫𝐨𝐮𝐧𝐝 𝐭𝐡𝐞 𝐌𝐨𝐨𝐧 𝐚𝐬 𝐩𝐥𝐚𝐧𝐧𝐞𝐝. Or it could change the heat shield itself.
𝐓𝐡𝐞 𝐟𝐢𝐫𝐬𝐭 𝐭𝐰𝐨 𝐨𝐩𝐭𝐢𝐨𝐧𝐬 𝐚𝐫𝐞 𝐯𝐞𝐫𝐲 𝐫𝐢𝐬𝐤𝐲, 𝐜𝐨𝐧𝐬𝐢𝐝𝐞𝐫𝐢𝐧𝐠 𝐭𝐡𝐞 𝐮𝐧𝐤𝐧𝐨𝐰𝐧𝐬. The latter involves a major delay of at least two years.”
The highlighted text is your own assertions, not based on the actual results of the NASA investigation into the matter.
What we know is that A)The observed char loss on Artemis I would have posed no risk to a crew, there was still ample margin on the heat shield , B)They observed the majority of the char loss during the second part of the skip re-entry sequence, and C)They’ve had a likely root cause identified for months and have been refining re-entry models since to hopefully reach flight rationale for the existing heat shield.
From what we’ve been publicly hearing from NASA officials and the GAO (and me personally from people within the Orion program familar with these heat shield meetings) it is unlikely they will opt to replace the heat shield on Artemis 2, potentially also on Artemis 3.
One likely solution I’ve heard is switching from a skip-entry to a direct entry to avoid the phase of flight where most of the char loss was observed, this would be for Artemis and potentially Artemis 3, with the downside of a less accurate splashdown location.
In any case I would no go around assuming how risky something of this nature is or isn’t without access to the relevant information.