According to the NASA engineers, Orion’s heatshield was not porous enough. When it got hot, the shield released gas, and if those gases couldn’t filter to the surface, they built up pressure until the shield cracked. But Artemis II could avoid the kind of heating that led to this problem by flying a steeper path on reentry. With that change, the engineers said, Orion could fly as-is.
At first, some voices outside of NASA warned that this plan was not enough, including multiple former astronauts. Hill argues these critics were not working with all the information, however. The heatshield situation is so technically complex, he says, it took his team of experts weeks to understand it fully, even with NASA engineers helping them. This January, two concerned former astronauts met with Hill’s review team and agency engineers to discuss NASA’s solution together, and afterward appeared to accept the decision to fly the heatshield.
Francesco Panerai, an assistant professor of aerospace engineering at the University of Illinois Urbana-Champaign, came to the same conclusion. Panerai has worked on heat protection at NASA in the past, and he was initially surprised to see the heatshield had failed so visibly. But after NASA offered its explanation, his surprise was “smoothed out.”
“That’s what the data say,” he explained. “It can be flown safe, within acceptable risks.”
Future missions, including Artemis III, should not have this issue with their heatshields. In the meantime, NASA does not expect it to pose a problem for the Artemis II astronauts.