NASA found Orion’s aerodynamic and aerothermal performance during Artemis II, including its heat shield and backshell protection, was in line with preflight engineering predictions and ground tests. The agency counted nine spots of char loss on the heat-shield dish; Artemis I had 103. NASA linked the reduction to a change in Artemis II’s entry profile.
What NASA found after Artemis II
NASA published its post-flight assessment on October 15, 2026. It reported that Orion reached a maximum velocity of 39 times the speed of sound and that exterior temperatures exceeded 2,204°C during the return. NASA also said the backshell’s 1,300 ceramic tiles performed as expected, with no signs of overheating.
The assessment said NASA was comparing post-flight laser scans with preflight measurements to determine how much material had receded from the heat shield.
Char-loss spots on Artemis I and Artemis II
NASA counted the spots of char loss on each mission’s heat-shield dish:
| Mission | Char-loss spots |
| Artemis I | 103 |
| Artemis II | 9 |
For Artemis II, NASA shortened the allowable downrange distance, limiting the time Orion spent in the temperature range associated with the Artemis I char-loss phenomenon. NASA attributed the reduced cracking and char loss to this entry change.
Why Avcoat’s permeability matters
NASA’s investigation of Artemis I found that gases produced as Avcoat ablated could not vent adequately in low-permeability areas. Pressure built up, cracking the char layer and releasing material. Where the Avcoat was permeable, the gases could escape.
For Artemis II, NASA changed the entry profile. For later lunar-return shields, including Artemis III’s, NASA described manufacturing improvements aimed at more uniform Avcoat with consistent permeability.
