Perhaps the biggest question going into the Artemis II mission this spring was how the heat shield at the base of the spacecraft would perform during reentry through Earth’s atmosphere.
The ablative heat shield, designed to char upon reentry while keeping the crew safe, had experienced unexpected losses of large chunks during a test flight in late 2022. After much deliberation, and not without controversy, NASA decided to fly the Artemis II heat shield as is but modify the spacecraft’s reentry trajectory.
Obviously, the heat shield worked. The crew of Artemis II, led by commander Reid Wiseman, safely splashed down in the Pacific Ocean after a triumphant trip around the Moon. Afterward, they and other NASA officials offered general comments, saying the heat shield looked good.
But how good? During a meeting of NASA’s Aerospace Safety Advisory Panel this week, its members had an opportunity to review NASA’s findings during a visit to the Ames Research Center in California. The condition of the heat shield, said panel member Paul Hill, was “highly satisfying.”
After the Artemis I mission in 2022, there were more than 100 char loss sites observed across the dish-shaped heat shield at the base of Orion, some of which were more than an inch deep. On the Artemis II heat shield, he said, there were approximately nine char loss sites observed. “So it was a big improvement,” said Hill, former director of Mission Operations at NASA.
Confidence in future Artemis missions
The success of the Artemis II heat shield, which now appears to have been confirmed by an extensive data review, will give NASA confidence in the performance of its deep-space vehicle for future lunar missions.
At the base of Orion are 186 blocks of a material called Avcoat; they are individually attached to provide a protective layer that allows the spacecraft to survive the heating of atmospheric reentry. Analysis after the Artemis I mission found that this Avcoat material was “impermeable,” essentially meaning it could not breathe. During reentry, gases became trapped in the heat shield, leading to cracking.
After considering several options, including swapping the heat shield out for a newer one with more permeable Avcoat, NASA decided instead to change Orion’s reentry profile. For Artemis II, it would return through Earth’s atmosphere at a steeper angle, spending fewer minutes in the environment where this outgassing occurred during Artemis I.
This largely worked, but there were some downsides. According to Hill, the new reentry profile reduced the vehicle’s “downrange” capability from 4,800 nautical miles to 1,775 miles. Downrange capability is the distance a spacecraft can travel, relative to the Earth’s surface, from the point of atmospheric reentry. A longer downrange is useful for finding a suitable splashdown site when weather conditions change, and it can give mission planners more options for return trajectories from the Moon.
For Artemis III and beyond, NASA is moving to a more permeable Avcoat material, which should allow them to reenter Orion without char loss and bring back a much larger downrange capability, Hill said.
Panel also impressed by NASA’s leadership
Toward the end of the safety panel’s meeting on Monday, a few members made some striking comments about their experiences working with NASA this year. For long-time listeners to meetings of the Aerospace Safety Advisory Panel, which is distinctly independent from NASA and tasked with identifying safety issues, these were eye-opening statements.
In describing the panel’s deliberations during its quarterly meeting, Hill said, “Words like impressive, stunning, and shocking were all brought up about the progress that the agency has made in the last year, and even more rapidly just in the last four months.”
This timeframe coincides with the “Ignition” event that NASA Administrator Jared Isaacman convened in late March to outline plans for a Moon base and changes to Artemis to accelerate the program. Isaacman has sought to give NASA’s deep-space exploration program a singular focus on getting back to the Moon and establishing a settlement there.
“In an empowering or enabling way, the changes that we are hearing in the leadership voice at the very top of the agency, and then down into the agency, are aligning the team on a coherent strategy and then taking the steps to execute on that strategy,” Hill said. “Again, it’s nothing short of impressive, and it’s directly related to recommendations we’ve had open for a number of years.”
The panel also lauded Isaacman for moving quickly, after becoming administrator in December 2025, to acknowledge some of NASA’s own failings during the troubled Starliner mission to the International Space Station. In February, NASA formally classified the 2024 crewed flight of the Starliner spacecraft as a “Type A” mishap, recognizing that the test flight was a serious failure. Previously, NASA had been reluctant to criticize its actions or those of Boeing, which built Starliner.
“To have the new leadership come in and basically turn around the culture with that one step, which was really the start of a big process change and how leadership was establishing a strategy and a vision, was really something to see,” said Susan Helms, chair of the panel and a former NASA astronaut and retired lieutenant general in the Air Force.
