As NASA ramps up preparations to send four people on a trip around the Moon and back, a debate is raging among experts and former astronauts over whether the mission’s spacecraft is as safe as the space agency claims.
NASA can launch as soon as March Artemis II. Launched into space by a Space Launch System (SLS) rocket, NASA’s Orion capsule will carry astronauts Reed Wiseman, Victor Glover, Christina Koch and Jeremy Hansen in a record-breaking loop around the moon.
NASA is confident that the mission will be successful and safe. But Orion has one potential drawback—in 2022 , On Artemis I, NASA’s last (uncrewed) mission to the Moon, the Orion capsule’s heat shield unexpectedly returned to Earth with extensive damage.
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Heat shields are important: When the spacecraft re-enter Earth’s atmosphere, they heat up, burning up in the sky like a shooting star. Without a protective layer, any living objects inside the returning spacecraft would be exposed to temperatures half as hot as the Sun’s surface, or 5,000 degrees Fahrenheit (2,760 degrees Celsius).
In Orion’s case, the heat shield is made of Avcoat – the same material that protected the Apollo capsule, with one key structural difference. For the Apollo spacecraft, the heat shield had a honeycomb-like structure containing more than 360,000 cells, each of which was filled with avcoat. The Orion’s heat shield, in contrast, is made of 200 large tiles of Avcoat. Together, they form a 16.5-foot diameter panel that is attached to the spacecraft.
Close-up of the burnt heat shield from the returned Apollo 16 command module, showing its honeycomb structure.
aroundtheworld.photography/ Alamy
“Heat shield on (the) Artemis II “The Orion capsule is an example of taking a legacy material that was tested and making basically the same material but in a slightly different way,” says Ed Pope, advanced materials specialist and heat shield engineer. In turn, this opened the door to new, unaccounted for risks with the material.
Space historian Jordan Beam of the University of Chicago says NASA chose to use Avcot to protect Artemis in 2009. “It was a long time ago, 2009, and it’s interesting that there have been very few actual re-entry trials,” says Bimm. “We’re here on the eve of launch, and there are open questions about (the heat shield).”
NASA has tested Avcoat’s performance extensively in ground-based laboratory tests and simulations, but a true reentry test is the “gold standard” according to Beam – and Orion’s Avcoat heat shield has only experienced one reentry test: Artemis I.
During the re-entry of Artemis I, large, brick-like pieces of Avcoat broke off from the Orion capsule, causing burn holes on the heat shield. NASA’s Office of Inspector General released a report of the damage in 2024 and concluded that any astronauts onboard would likely be OK.
Artemis I’s heat shield damaged
“When I looked at those pictures, I knew this whole design was wrong,” Pope says, suggesting that there was a difference in the decision to change the structure of the heat shield from the Apollo-era design.
Importantly, by the time the report came out, it was too late for NASA to replace the heat shield Artemis II Without significantly delaying the mission – which is already years behind schedule – or increasing its budget.
Instead, NASA decided to change Orion’s re-entry path so that Artemis II The heat shield will withstand greater stress than the Artemis I but for much less time. According to the agency, the change will ensure Artemis II Not a repeat of Artemis I. But, Beam says, by leaving the heat shield unchanged, the agency hasn’t helped address any concerns.
Pope says the heat shield risks posed by Artemis I have also not been fully addressed.
“We know there is an additional risk that can be addressed, and we also know how to address it, because Artemis III “They know they can build a separate heat shield, and they have built it or are building it, but that could lead to even more slippage in the schedule.”
NASA is adamant on this Artemis II Will take off only when ready – and the heat shield on the mission’s Orion spacecraft is safe enough to successfully return the four astronauts aboard to Earth, even if it suffers damage. “From a risk perspective, we feel very confidentA senior NASA official said at a press conference in September 2025 Artemis II.
NASA Administrator Jared Isaacman echoed that sentiment in January social media postWriting that “human spaceflight will always involve uncertainty” but NASA is committed to using science, technology, and engineering to reduce the risks. “Crew safety remains our top priority at NASA. With this disciplined approach every step of the way, we are moving steadily and confidently toward sending astronauts farther into space than ever before.”
And at a press conference in early January, Isaacman said that NASA has “complete confidence in the Orion spacecraft and its heat shield, based on rigorous analysis and the work of exceptional engineers who followed the data throughout the process.”
Pope points out that space is a risky business, no matter how much you work to minimize those risks. But that’s why concerns about the heat shield persist, he says: NASA didn’t make any changes to the material or re-test it on the uncrewed mission.
“I think it’s possible that Artemis II The mission will end successfully because I don’t believe that the risk here is somehow greater than 50 percent,” Pope says. “But I think the risk of heat shield failure is somewhere between one in five to one in 50.”
Still, the fact remains that former astronauts are among those criticizing the agency for using a potentially flawed heat shield Artemis II, The mission to send humans further into space than ever before has attracted significant media attention. Among the most vocal is former NASA astronaut Charles Camarda, who flew on the now-defunct Space Shuttle Search On NASA’s first crewed mission since the 2003 Space Shuttle, in 2005 Colombia The disaster, which killed seven astronauts. Point to be noted is that Colombia Tragedy occurred when a piece of insulation foam around the Space Shuttle’s external tank broke off and struck the tiles of the spacecraft’s thermal protection system – penetrating its heat shield and breaking up the spacecraft upon re-entry.
“This discourse of worry and concern is based on a history of disasters,” Bimm said, nodding. Colombia and 1986 contender The disaster, which also killed seven astronauts. “This is not without precedent.”
Camarda has repeatedly expressed its concern over NASA’s decision to use similar heat shields Artemis II It was used for Artemis I on uncrewed missions to test new trajectories. But former astronaut Danny Olivas, who took part in NASA’s review of what happened to Artemis I’s heat shield, has said that NASA has done enough to prevent any risks caused by the heat shield.acceptable“
“No fatal disaster in NASA’s history has been caused by astronauts,” says Bimm. “It’s never been the operator’s fault. It’s because of the design and system choices, and it’s the kind of big, big science, socio-technical systems that have gotten them.”
