Researchers Make Breakthrough in Observing Heat Shield Ablation in Real Time
BYLINE: Gianna FazioLiu
Newswise — When spacecraft reenter Earth’s atmosphere at hypersonic velocities, their protective heat shields are subjected to extreme conditions, with temperatures exceeding 3,000 degrees Fahrenheit. These shields use specialized materials designed to absorb heat through a controlled degradation process known as ablation, sacrificing their outer layers to safeguard the vehicle and its crew.
To design these critical materials effectively, researchers have traditionally relied on pre- and post-test observations, which limits their understanding of the degradation process at a microscopic level. However, a collaborative effort at the Advanced Light Source (ALS) at Berkeley Lab has now enabled scientists to observe this process in real time.
Researchers from the University of Illinois Urbana-Champaign and NASA employed in situ X-ray micro-computed tomography (micro-CT) to study superlight ablators—critical materials used in spacecraft backshells. By heating samples to 1,652 degrees Fahrenheit and capturing detailed 3D images over time, the team was able to document the chemical decomposition and changes in porosity during the heating process.
“Watching how heat shield materials degrade during heating has transformed atmospheric entry research, providing insights into internal structural changes that impact ablation,” said Vishnu Oruganti, now a researcher at NASA’s Johnson Space Center. The technique has been applied to major NASA ablative heat shield materials relevant to missions like Artemis and Mars entry.
Balancing Act in Imaging
In an innovative approach, the team tackled the challenge of rapidly collecting extensive images while maintaining detail. They utilized AI-driven super-resolution techniques to enhance images captured at lower resolutions, allowing them to monitor large areas while also capturing fine structural details.
High-intensity flux from the light source enabled quick imaging, while a single-wavelength beam was used for detailed snapshots of the materials before and after heating. The AI technology helped create a complete high-resolution record of each material’s changes throughout the heating process.
The researchers found significant differences between the two heat shield materials studied: SLA-561V, which contains cork, and SLA-220, a rubber-like silicone matrix. The cork-filled material decomposed and left empty pockets, while SLA-220 formed a dense network of channels in response to heat. These structural differences affect how the materials perform under reentry conditions, influencing gas and heat flow.
Conclusion
This research provides engineers direct measurements of how heat shield materials change at a microscopic level during atmospheric reentry, enhancing model development and improving safety for future crewed missions. The findings, backed by NASA and the advanced capabilities of the ALS, promise to bolster mission planning and execution.
For more details, visit Lawrence Berkeley National Laboratory and Department of Energy.
