A real-time look inside spacecraft heat shields during extreme heat conditions

A heat shield removed from NASA's Orion spacecraft and inspected following the Artemis I test flight was analyzed at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. Researchers used an X-ray tomography instrument to recreate realistic, evolving reentry conditions and captured real-time images of the ablation process. The study found that the heat shield materials degrade in complex, multiphase chemical reactions under extreme temperatures, providing detailed insights into how materials change under reentry conditions. The findings improve the design of thermal protection systems for space missions, including NASA's Artemis and Mars entry missions.

• "The study found that the heat shield materials degrade in complex, multiphase chemical reactions under extreme temperatures, providing detailed insights into how materials change under reentry conditions."
• "The research is published in the journal npj Materials Degradation."
• "The findings give engineers something they have not had before: direct measurements of how heat shield materials change at a microscopic level under the thermal conditions of atmospheric reentry."

The research involved studying two commercial ablators, SLA-220 and SLA-561V, which are used in different parts of spacecraft backshells and have different compositions. The team heated the samples to 1,652 degrees Fahrenheit (900 degrees Celsius) and imaged them on the micrometer scale at multiple time points. The AI-based super-resolution method allowed the team to capture large-volume, lower-resolution scans at short intervals while preserving fine microscopic details. The results showed that SLA-561V contains cork, which chemically breaks down and disappears, leaving open, empty pockets, while SLA-220 contains a rubber-like silicone matrix that forms a dense, branching network of interconnected channels. These differences affect how each material performs as a heat shield.

• "The AI-enhanced imaging revealed a striking difference between the two heat shield materials."
• "SLA-561V contains cork—the same natural material used in wine bottle stoppers—as a structural filler."
• "SLA-220 contains no such organic filler; instead, its rubber-like silicone matrix responds to heat by forming a dense, branching network of interconnected channels."

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