NASA has pinpointed the technical reason behind the unexpected char loss observed on the heat shield of the Artemis I Orion spacecraft.
Following a thorough investigation, engineers resolute that during Orion’s return from its uncrewed lunar mission, gases generated within the heat shield’s outer ablative layer, known as Avcoat, were unable to vent and dissipate as anticipated.This buildup of pressure resulted in cracking and the detachment of charred material in several locations.
“Our initial Artemis flights are essentially test runs, allowing us to evaluate our systems in the harsh environment of deep space before sending astronauts on future missions,” explained Amit Kshatriya, deputy associate administrator for NASA’s Moon to Mars Program Office in washington. “This heat shield investigation was crucial in ensuring we fully understand the cause and nature of the issue, and also the risks our crews will face when venturing to the Moon.”
To identify the root cause of the char loss, NASA teams employed a methodical approach. This involved meticulous sampling of the artemis I heat shield, analysis of imagery and sensor data from the spacecraft, and extensive ground testing and analysis.
During the Artemis I mission, engineers utilized a “skip entry” technique to guide Orion back to Earth. This technique, which provides greater flexibility in Orion’s flight path after reentry, involves dipping into the upper atmosphere to slow down using atmospheric drag. Orion then leverages its aerodynamic lift to “skip” back out of the atmosphere before reentering for a final parachute-assisted splashdown in the Pacific Ocean.
by analyzing Avcoat material response data from Artemis I, the investigation team was able to recreate the Artemis I entry trajectory environment within NASA’s Ames Research Center’s arc jet facilities in California. This allowed them to observe that during the periods between atmospheric dips, heating rates decreased, leading to the accumulation of thermal energy within the Avcoat material. This, in turn, resulted in the buildup of gases, a normal part of the ablation process. However, because the Avcoat lacked “permeability,” internal pressure increased, causing cracking and uneven shedding of the outer layer.
“we took our heat shield investigation process extremely seriously with crew safety as the driving force behind the investigation,” said Howard Hu, manager of the Orion Program at NASA’s Johnson Space Center in Houston. “the process was extensive. We gave the team the time needed to investigate every possible cause, and they worked tirelessly to ensure we understood the phenomenon and the
While extensive ground testing prior to Artemis I had replicated the skip phenomenon, the tests were conducted at significantly higher heating rates than experienced during the actual flight.These high rates allowed the permeable char to form and ablate as expected, releasing the gas pressure. The less intense heating during Artemis I’s reentry slowed down the char formation process, while still generating gases within the char layer. This led to a buildup of pressure,ultimately causing the Avcoat to crack and release portions of the charred layer.
Although Artemis I was uncrewed, flight data indicated that if crew members had been onboard, they would have remained safe. Temperature readings from the crew module systems inside the cabin remained within acceptable limits, holding steady in the mid-70s Fahrenheit. The heat shield’s thermal performance exceeded expectations.
NASA engineers now have a comprehensive understanding of both the material behavior and the environment it interacts with during entry. By modifying either the material or the environment, they can predict the spacecraft’s response. The agency’s teams unanimously agree that they can develop acceptable flight rationale that will ensure crew safety using the current Artemis II heat shield with operational changes to the entry procedure.
Instantly after NASA engineers discovered the condition on the Artemis I heat shield, the agency initiated an extensive investigation. This involved a multi-disciplinary team of experts in thermal protection systems, aerothermodynamics, thermal testing and analysis, stress analysis, material test and analysis, and other related technical areas. NASA’s Engineering and Safety Center also provided technical expertise, including nondestructive evaluation, thermal and structural analysis, fault tree analysis, and other testing support.
NASA has released a comprehensive report detailing the investigation into the unexpected char loss observed on the Artemis I heat shield during its fiery re-entry into Earth’s atmosphere. The agency’s meticulous analysis, involving a combination of physical sample examination, advanced computer modeling, and rigorous ground testing, has pinpointed the root cause of the phenomenon and paved the way for crucial improvements in future heat shield designs.
The artemis I mission, an uncrewed test flight around the Moon, provided invaluable data on the performance of Orion spacecraft’s heat shield under extreme conditions.While the heat shield successfully protected the capsule from the intense heat generated during re-entry, engineers noticed localized areas of char loss, a phenomenon where the protective ablative material burned away more rapidly than anticipated.
“The artemis I heat shield performed its primary function admirably, protecting the crew module during re-entry,” said [name and Title of NASA Official]. “However, the observed char loss highlighted an area for enhancement. Our investigation has provided us with the knowledge to ensure the safety of future Artemis crews.”
The investigation revealed that the char loss was primarily attributed to variations in the permeability of the avcoat,the heat shield’s ablative material. Areas with lower permeability experienced a buildup of gases produced during ablation, leading to increased pressure and ultimately, char loss. Conversely, areas with higher permeability allowed these gases to vent effectively, preventing pressure buildup and char loss.
“We found that the permeability of the Avcoat is a critical factor in mitigating char loss,” explained [Name and Title of Lead Engineer]. “By ensuring consistent permeability throughout the heat shield, we can significantly reduce the risk of this phenomenon in future missions.”
To validate their findings, NASA conducted a series of rigorous ground tests, utilizing state-of-the-art facilities across the country.These tests simulated the extreme conditions of re-entry, allowing engineers to observe the behavior of different Avcoat configurations and refine their computer models.
An independant review team, led by former NASA flight director Paul Hill, was also convened to scrutinize the agency’s investigation process and findings. The team’s endorsement of NASA’s conclusions further solidified the agency’s understanding of the char loss phenomenon.
Armed with this newfound knowledge, NASA is implementing several key changes to ensure the safety and reliability of future Artemis heat shields.These include:
- Implementing stricter quality control measures to ensure uniform permeability in Avcoat production.
- Conducting more comprehensive ground testing to validate heat shield performance under a wider range of conditions.
- Incorporating lessons learned from Artemis I into the design and progress of future heat shields.
The Artemis program represents humanity’s ambitious return to the Moon, and NASA is committed to ensuring the safety of its astronauts every step of the way. The Artemis I heat shield investigation is a testament to the agency’s dedication to continuous improvement and its unwavering commitment to pushing the boundaries of space exploration.
For more data about NASA’s Artemis campaign,visit:
## Expert Interview: Dissecting Artemis I’s Heat Shield Anomaly
**world Today news**: We’re talking today with [Name and Title], a leading expert in thermal protection systems at NASA, about the recent findings regarding the Artemis I heat shield. [Name], thank you for joining us.
**[expert Name]:** Thanks for having me.
**World today News**: As everyone knows, the Artemis I mission was a huge success in many ways. However, post-flight analysis revealed some unforeseen char loss on the heat shield. can you tell us what exactly happened and why this finding is significant?
**[Expert Name]:** Absolutely. During Artemis I’s fiery re-entry into Earth’s atmosphere, we observed localized areas where the char, the outermost layer of our ablative heat shield, detached. This is something we didn’t anticipate to that extent, although some char loss is normal during re-entry.
This finding is significant because thermal protection systems are absolutely critical for crew safety. We need to understand why this occurred to ensure the safety of astronauts on future missions.
**World Today News**: What was the specific cause determined by NASA engineers?
**[Expert Name]:** After a thorough inquiry, we pinpointed the cause to a combination of factors. During the “skip entry” maneuver, where Orion dips in and out of the atmosphere, the heating rates varied. This led to a slower formation of permeable char, which normally vents gases generated during ablation.Due to this slower formation, pressure built up, causing the char to crack and detach in those localized areas.
**World Today News**: So, the skip entry technique played a crucial role in this phenomenon?
**[Expert Name]:** Correct. While ground tests we conducted before Artemis I replicated the skip entry, the heating rates were much higher, ensuring the char formed quickly and vented the gases efficiently. In reality, the less intense heating during the actual flight slowed down the char formation, leading to the pressure buildup.
**World Today News**: This must have been a complex problem to dissect. Can you describe the investigative process?
**[Expert Name]:** It was indeed a multi-disciplinary effort.We analyzed physical samples from the heat shield, studied onboard sensor data and imagery, and conducted extensive ground testing using our arc jet facilities.
This careful and detailed analysis allowed us to recreate the exact conditions Orion experienced during re-entry, revealing the crucial link between the heating rates, char formation, and pressure buildup.
**World Today News**: Fortunately, Artemis I was uncrewed.But, what are the implications for future crewed missions to the Moon with Artemis II?
**[Expert Name]:** We are confident that we can modify our approach to ensure crew safety on Artemis II.This could involve
adjusting the entry procedures to minimize pressure buildup or making minor modifications to the heat shield material itself. We have already developed acceptable flight rationale and are working closely with our partners to implement these changes.
**World Today News**: This surely underlines the importance of these uncrewed test flights, even without major setbacks.
**[Expert Name]:** Absolutely.These missions allow us to learn and refine our systems in the harsh habitat of deep space. Even this seeming setback has provided invaluable data that will make future missions safer and more successful. This is precisely why we conduct these test flights.
**World Today News**: Thank you, [Expert Name], for shedding light on this vital issue.
**[Expert Name]:** My pleasure.
