The upcoming Artemis 2 mission, slated to carry four astronauts around the moon as early as March, will rely on a redesigned reentry profile to mitigate a heat shield issue observed during the uncrewed Artemis 1 flight. NASA identified unexpected chipping of the Orion spacecraft’s ablative thermal protection material after its 2022 atmospheric plunge, raising concerns about crew safety for future missions.
The Problem: Trapped Gases and Material Loss
Post-flight analysis revealed over 100 areas where the Avcoat ablative material broke off during reentry. Investigations showed that insufficient venting of gases within the heat shield caused pressure buildup, leading to cracking and char loss. This was not a safety failure — the capsule remained within acceptable temperature limits — but it highlighted a flaw in the manufacturing process.
The core issue stemmed from how Avcoat, a material also used in the Apollo missions, was applied. The current process uses pre-machined blocks bonded to the heat shield instead of manually filling honeycomb cells, saving time but creating a pressure trap.
Solution: A Steeper, Direct Reentry
To address the issue, NASA has altered the Artemis 2 trajectory. Rather than the “skip entry” technique used in Artemis 1 (which dips into and out of the atmosphere), the spacecraft will follow a steeper, more direct descent. This change minimizes the time spent in the temperature range where the heat shield material was observed to degrade.
Lockheed Martin, Orion’s primary contractor, has performed extensive testing and concluded that the modified trajectory will reduce char loss to safe levels. The Avcoat formula remains unchanged for Artemis 2, though adjustments to density are planned for Artemis 3 to improve gas venting.
Ongoing Risks and Oversight
Despite the modifications, concerns remain. A recent report by NASA’s Office of Inspector General (OIG) flagged Artemis 2’s preparation as the agency’s most time-sensitive challenge. While the current plan is technically feasible, it does not eliminate the heat shield risk entirely for future missions.
The OIG report noted that the modified approach relies on successful testing and has already caused delays to the Artemis program. The behavior of the heat shield during the steeper reentry will be closely monitored, as superheated plasma will temporarily block communications during the descent.
“NASA intends to reuse the heat shield design for Artemis 2 while flying a modified reentry trajectory that is less severe.” — NASA OIG Report
Ultimately, the success of Artemis 2 hinges on the heat shield’s performance under the new reentry profile. This mission represents a critical step towards returning humans to the moon, but it also underscores the inherent risks and complexities of space exploration.
