NASA faces tough decisions on Orion capsule heat shield for Artemis Moon mission

NASA continues to work in testing mode to determine what is behind the ablative thermal protection material that unexpectedly broke off from Artemis 1 Orion’s heat shield during its re-entry into Earth’s atmosphere on December 11, 2022.

Orion spacecraft The Artemis 1 mission splashed down in the Pacific Ocean after a 25.5-day mission.

During a high-speed return from lunar distance at 25,000 mph, the Orion crew module’s thermal protection system must withstand very high temperatures to ensure the safety of crew members. At 16.5 feet in diameter, Orion’s heat shield is the largest of its kind designed for missions carrying astronauts.

Root cause

But upon post-flight analysis Artemis 1 heat shield, NASA identified more than 100 locations where ablative thermal protection material was released during its rapid re-entry into the atmosphere.

Work to determine the root cause was completed last summer, said Laurie Glaze, deputy assistant administrator (acting) for the Exploration Systems Development Mission Directorate.

Speaking Oct. 29 at the Lunar Research Review Group’s annual meeting in Houston, Texas, Glaze did not specify what the root cause had been discovered.

However, Glaze said additional testing is ongoing before any final decisions are made. This test will be completed by the end of November and will then be handed over to NASA chief Bill Nelson for a final decision.

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The Orion heat shield is made from Avcoat ablative material. (Image credit: Photo: Lockheed Martin)

Artemis II

Meanwhile, NASA is moving ahead with preparing Artemis 2’s hardware to launch a four-person crew for a stay beyond the confines of the spacecraft. moonthen return to Earth.

The Artemis 2 crew is scheduled to leave Earth no earlier than September 2025 on a 10-day mission.

In classic “wait a minute” style, NASA’s Office of Inspector General (OIG) report, NASA’s Preparedness for the Manned Artemis II Mission to Lunar Orbit, was released this past May, addressing this and other issues before departure. from the first human crew on the Moon since 1972 – Apollo 17 mission.

The Arc Jet facility at NASA’s Ames Research Center in California’s Silicon Valley was used to study unexpected heat shield problems discovered after the 2022 Orion Artemis I capsule flight. (Image courtesy of NASA OIG)

To ensure the safety of the Artemis 2 mission crew, the OIG report recommends that the Deputy Administrator for Exploration Systems Development Mission Management ensure that the root cause of Orion’s charred heat shield release is well understood before launching the Artemis 2 mission.

The OIG report calls for an analysis of Orion’s separation bolts using updated models that account for char loss, design changes, and operational changes to Orion prior to Artemis 2’s launch.

The NASA OIG report also noted that “manned spaceflight by its very nature is risky, and the Artemis campaign is no exception. We encourage NASA leadership to continue to balance achieving its mission goals and schedule with prioritizing the safety of its astronauts. and take the time necessary to avoid any unnecessary risk.”

Changes in Avkota

The heat shield is made from the same ablative material called Avcoat that was used on the Apollo lunar and Earth return missions. However, according to Lockheed Martin, which developed Orion’s thermal protection system, the construction process has changed.

“Instead of workers filling 300,000 honeycomb cells with ablative material one by one, then heat-curing the material into the desired shape, the team now produces Avcoat blocks—fewer than 200 in total—that are pre-machined to fit into their positions and bonded to a carbon fiber heat shield shell,” the aerospace firm’s website explains. This process saves time when applying Avcoat – about a quarter time.

Engineers and technicians check the heat shield of the Artemis 1 Orion spacecraft after splashdown in the Pacific Ocean on December 11, 2022. (Image credit: NASA/Skip Williams)

So here’s the lingering and nagging question: Is it possible that changes will be needed at Avcoat? If so, this solution would likely require detaching the heat shield from the Artemis 2 Orion capsule.

Heat Shield Hiccup

When the heat shield issue first came to light, Space.com contacted NASA’s Orion program office. Johnson Space Center for your comment regarding the heat shield malfunction.

“During the post-flight inspection of Artemis 1, engineers observed changes in the Avcoat material in the appearance of Orion’s heat shield. Some areas of expected char material did not disappear as computer modeling and ground tests predicted, and the release of char material was slightly greater. during reentry than expected,” the program office said.

“We would expect the material to disappear at the 5,000 degrees Fahrenheit temperature that a spacecraft encounters upon re-entry into the Earth’s atmosphere and to see charring of the material as a result of the chemical reaction, but we did not expect small pieces to break off rather than be removed,” NASA added in a statement.

(Image credit: Lockheed Martin)

Healthy margins

“We don’t yet know exactly how much has been released so we are analyzing the data, but there is a significant supply left from the original Avcoat and the temperature data inside the cabin remained at expected levels, so if the crew had been turned on to the council they would not have been in danger.” , explains a statement from the program office.

(Image courtesy of NASA OIG)

“It is too early in our testing and analysis to come to any potential recommendations or solutions to further release coal,” NASA responded. “It’s possible that this phenomenon could simply be part of what the heat shield is and what we expect when we return from the Moon, but we’ll let the data inform us.”

Finally, NASA’s Orion Program Office stated, “We will continue to consider changes that may occur during re-entry as we want to ensure that we have a significant margin against the various types of uncertainties that may arise during the spacecraft’s re-entry.” atmosphere.” Our teams want to make sure we have the best heat shield to keep people moving forward.”

When cross-checking with NASA’s Orion program office, Space.com was told that “we have not made any decisions yet, but NASA will provide an update on our plans once the investigation is complete and we have determined a path forward.”

NASA faces tough decisions on Orion capsule heat shield for Artemis Moon mission

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