NASA Identifies Root Cause of Orion Heat Shield Char Loss

NASA has identified the root cause of the unexpected char loss on Orion’s heat shield after it returned from the Artemis I uncrewed test flight to the Moon almost two years ago.  Solving the problem is required before the next mission, Artemis II, can launch with a crew of four. How to do that is still under discussion, with testing underway. The heat shield for Artemis II is already built so options are limited. A NASA official said today the NASA Administrator will make the final decision on how to proceed.

Speaking at a meeting of NASA’s Lunar Exploration Analysis Group (LEAG) this morning, Lori Glaze declined to explain the root cause, only that they know what it is and are developing options to deal with it. Glaze is on detail to NASA’s Exploration Systems Development Mission Directorate as Acting Deputy Associate Administrator from her usual position as Director of the Science Mission Directorate’s Planetary Science Division. ESDMD is in charge of the Artemis program at NASA headquarters.

NASA established an internal team as well as an Independent Review Board to investigate the char loss. Glaze confirmed that both studies were completed at the end of the summer with conclusive results.

“We’ve been able to demonstrate and reproduce it in the Arcjet facilities out at Ames [Research Center]. What we’re doing now is assessing what is the appropriate approach for Artemis II regarding the heat shield. You know what to do for future missions, but the Artemis II heat shield is already built.

“So how do we assure astronaut safety with Artemis II?   Right now there’s some additional testing ongoing that needs to conclude before we make a determination. We expect that additional testing to be done by the end of November and then we anticipate discussions with the Administrator who will make the final decision on how to proceed.”

Lockheed Martin is the prime contractor for the Orion capsule that will take astronauts from the surface of Earth to lunar orbit. Artemis I was an uncrewed test flight that launched on November 16, 2022 and splashed down in the Pacific Ocean on December 11 after a 25 day 11 hour mission that included a lunar orbit.

Orion has an ablative heat shield and material is intended to burn off — “char” — because of the heat of reentry.

In this case the “char loss” was much greater than anticipated. The extent of the loss wasn’t known publicly until the NASA Office of Inspector General published a report with photographs.

NASA established an Independent Review Board led by Paul Hill, but the results have not been made public.  Hill is a former NASA space shuttle flight director and member of NASA’s Aerospace Safety Advisory Panel. (ASAP is holding a public meeting on Thursday to report the results of its third quarter review of safety at NASA, but it’s not clear if this topic will be discussed.)

In January, NASA Administrator Bill Nelson delayed the launch of Artemis II from the end of 2024 to September 2025, and Artemis III from the end of 2025 to September 2026.

Artemis II is a crewed test flight around the Moon. The four astronauts — three Americans and one Canadian — will not land. In fact, they will not even enter lunar orbit. They will fly a “free return” trajectory that will bring Orion back to Earth even if something goes awry with the propulsion system. Artemis III is the mission that will land astronauts on the Moon for the first time since the Apollo program.

Astronaut safety is paramount at NASA. Whether they will be able to meet the September 2025 launch date remains an open question.