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NASA’s Artemis Mission: A Technical Overview
NASA’s Artemis I mission was deemed a resounding success in late 2021, as the Space Launch System rocket and Orion spacecraft executed a flawless unpiloted flight around the Moon. The mission set the stage for Artemis II, which will mark the program’s inaugural crewed mission. However, one anomaly noted during Artemis I pertained to the Orion spacecraft’s heat shield.
Heat Shield Abnormality
Upon re-entry into Earth’s atmosphere, engineers observed that the heat shield on the Orion spacecraft ablated differently from predictions made by computer models. A larger amount of charred material peeled off the heat shield than anticipated, and the removal was uneven in nature. Orion’s heat shield comprises Avcoat, a material designed to burn off as the spacecraft hurtles towards Earth at speeds reaching 25,000 mph (40,000 km per hour). During its return from the Moon, Orion encountered temperatures as high as 5,000° Fahrenheit (2,760° Celsius) – surpassing those experienced during re-entry from low-Earth orbit. Despite this issue, the Orion spacecraft safely splashed down in the Pacific Ocean, with engineers identifying the uneven charring during post-flight inspections.
Ongoing Investigation
Amit Kshatriya, responsible for Artemis mission development within NASA’s exploration division, confirmed that an investigation into the heat shield anomaly is underway. Prior to the Artemis II mission, NASA aims to ascertain the root cause of the issue. This second mission will involve sending astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen on a 10-day journey around the far side of the Moon – marking humanity’s return to lunar orbit since the final Apollo mission in 1972.
Delay and Resolution
In light of the unresolved heat shield investigation, NASA announced a launch delay for Artemis II from late 2024 to September 2025. The agency conducted sub-scale heat shield tests in wind tunnels and arc jet facilities to gain insights into the cause of the uneven charring. While it is unlikely that modifications to the Orion heat shield for Artemis II are necessary, potential alterations could lead to mission delays.
Flight Trajectory Analysis
Engineers are examining various re-entry trajectories for the Orion spacecraft during Artemis II. Unlike the “skip reentry” profile utilized during Artemis I, which enables precise splashdowns and reduced g-forces, direct and ballistic entry profiles are also under consideration. Understanding the performance of the heat shield in each reentry scenario is crucial towards ensuring crew safety.
Future Considerations
Upon identifying the cause of heat shield anomalies, NASA will develop flight rationale to establish spacecraft safety for Artemis II. Discussions are ongoing to assess the suitability of Orion heat shields for future, high-speed reentry profiles as astronauts return from lunar missions. As preparations for Artemis II progress, the Orion spacecraft is currently undergoing environmental testing at NASA’s Kennedy Space Center.
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