Now that the four astronauts who flew around the moon are safely home, NASA is investigating how its spacecraft fared during the final minutes of the Artemis II mission.
The Orion capsule’s heat shield — the protective layer at the bottom engineered to prevent it from burning up during the plunge through Earth’s atmosphere — had a known design flaw. During the uncrewed Artemis I test flight in 2022, parts had cracked and broken off during atmospheric re-entry.
Because of that, the Artemis II crew descended faster and at a steeper angle than the path originally planned for the Orion spacecraft, in order to minimize the time it was exposed to the most extreme temperatures.
That approach accomplished its goal — NASA astronauts Reid Wiseman, Christina Koch and Victor Glover and Canadian astronaut Jeremy Hansen emerged in good health and good spirits. Now, the question is: How well did the heat shield actually protect them?
In the hours after splashdown, space wonks noticed a large, unusual-looking white patch on the otherwise dark and scorched heat shield. The patch drew attention because it looked like it could be a sign of damage.
NASA did not respond to requests for comment about the state of the heat shield or when a full analysis of its performance would be available.
However, in response to a post on X from Eric Berger, an editor at Ars Technica, about the white patch, NASA Administrator Jared Isaacman said the white spot was consistent with the agency’s expectations.
“No unexpected conditions were observed,” Isaacman wrote, adding, “the discoloration was not liberated material.”
He said the white spot corresponds to the heat shield’s “compression pad area” and aligned with what NASA engineers had seen in pre-flight testing.
“I am hesitant to get ahead of a proper data review, but I understand the space community’s curiosity, especially when imagery can give the impression of a problem,” Isaacman wrote. “As you would expect, engineers were eager to inspect the heat shield, starting with diver imagery shortly after splashdown and continuing with the review aboard the ship.”
NASA indeed began investigating the Orion heat shield’s performance immediately after the spacecraft splashed down in the Pacific Ocean on Friday, capping the crew’s 10-day flight around Earth and the moon.
Lori Glaze, acting associate administrator of NASA’s Exploration Systems Development Mission Directorate, said aircraft were positioned near the landing site to capture images of and early data on the heat shield.
“We also had divers below the surface that took imaging of the heat shield before it was brought on to the [USS John P.] Murtha so that we could understand exactly what state it’s in after it landed,” Glaze said Friday evening in a post-splashdown news briefing. “And so we’ve already begun the data-gathering piece of it.”
The spacecraft is currently being transported back to NASA’s Kennedy Space Center in Florida, where the agency will conduct further analysis.
“We will complete a full data review across all systems, including the thermal protection system, and make the results publicly available,” Isaacman wrote in his response on X.
The Artemis II mission was NASA’s first time launching humans toward the moon in more than 50 years, and the first time the agency’s Space Launch System rocket and Orion capsule had ever lifted off with a crew onboard. The astronauts traveled farther from Earth than anyone before them, and they were the first people to see the entire far side of the moon with their own eyes.
Because of those firsts, the entire mission was closely watched, but that was particularly true of the final 15 minutes.
After the Orion heat shield sustained unexpected damage during the Artemis I test flight, NASA launched a yearslong investigation. The agency found that gases had gotten trapped inside portions of the heat shield while the capsule was streaking through the atmosphere, allowing pressure to accumulate. The built-up pressure caused parts of the shield’s outer material to crack.
Atmospheric re-entry is always a dangerous part of human spaceflight, because a spacecraft can be exposed to temperatures of around 5,000 degrees Fahrenheit. But for Artemis II, the heat shield’s design flaw meant fears were especially high.
Charlie Camarda, a former NASA astronaut, had publicly urged NASA not to launch the mission with the existing design.
For future Artemis missions, NASA is planning a redesigned heat shield for the Orion spacecraft. But the capsule for Artemis II had already been assembled by the time the agency learned about the cracking issue. So, to reduce the risk for the crew, mission managers came up with the modified path for atmospheric re-entry that the Orion capsule followed on Friday.
Flight directors knew how high the stakes were.
“It’s 13 minutes of things that have to go right,” Jeff Radigan, NASA’s Artemis II flight director, said at a news briefing Thursday, the second-to-last day of the mission.
“Let’s not beat around the bush,” he added. “We have to hit that angle correctly.”
Thankfully, NASA did that: Mission managers said the capsule followed a near-perfect flight path on re-entry and landed within less than a mile of its targeted splashdown site.
