Paul Hill Leading IRB on Orion’s Heat Shield

Paul Hill Leading IRB on Orion’s Heat Shield

Paul Hill, a former NASA space shuttle flight director and member of the Aerospace Safety Advisory Panel, is heading an Independent Review Board to assess the agency’s investigation of why the heat shield on the Orion spacecraft lost so much material during the 2022 uncrewed Artemis I test flight. NASA has been trying to understand why the heat shield behaved differently than expected as it prepares for the first flight with a crew. NASA’s Office of Inspector General recently released a report identifying the heat shield as a pacing item for that flight, currently scheduled for September 2025.

Built by Lockheed Martin, the Orion capsule is protected by an ablative coating, Avcoat, that intentionally peels off or chars from the heat of reentry. During the Artemis I test flight, however, it eroded in an unexpected manner as the capsule plummeted through Earth’s atmosphere on December 11, 2022 at nearly 25,000 miles per hour.

The May 1, 2024 report from the NASA OIG revealed that at more than 100 locations “portions of the char layer wore away differently than NASA engineers predicted, cracking and breaking off the spacecraft in fragments that created a trail of debris rather than melting away as designed.” The heat shield successfully protected the module and its systems, but the anomalous behavior “creates a risk that the heat shield may not sufficiently protect the capsule’s systems and crew from the extreme heat of reentry on future missions.”

At an April 26 meeting of the NASA Advisory Council’s Human Exploration and Operations Committee, Amit Kshastriya, who heads NASA’s Moon to Mars program, said NASA is determined to understand what happened on that mission, which used a “skip-return” trajectory, and how the heat shield might respond to other types of trajectories. They have been told by the top levels of the agency to “not worry about building flight rationale,” but “make sure you understand the fundamental physics of what’s happening.”

In fact, NASA established an Independent Review Board (IRB) in April to take an unbiased look at the heat shield investigation.

Paul Hill. Photo credit: Bill Stafford, 07-23-2013

In an emailed statement, NASA said: “In late April, NASA chartered an independent review team which includes experts outside the agency to conduct an independent evaluation of the investigation results. That review, scheduled to be complete this summer, ensures NASA properly understands this condition and has corrective actions in place for Artemis II and future missions.”

Today, NASA told that the IRB is headed by Paul Hill.

The independent review team of NASA’s investigation into the Artemis I Orion heat shield is being led by Paul Hill. He served as the lead space shuttle flight director for Return to Flight after the Columbia accident, led NASA’s mission operations directorate, and is a current member of the agency’s Aerospace Safety Advisory Panel, though his role as chair is not associated with his ASAP membership. — NASA

As a test flight, Artemis II will go around the Moon, but not orbit or land. Instead it will be on a “free return” trajectory that will bring the spacecraft and its four person crew back to Earth even if the engines do not work properly.

The Artemis II crew, L-R: Jeremy Hansen (Canadian Space Agency), Victor Glover (NASA), Reid Wiseman (NASA), Christina Koch (NASA).

Artemis II had been scheduled for this year, but in January NASA announced a one-year delay along with a similar slip for Artemis III, the first mission to put astronauts on the lunar surface since the Apollo program. Artemis II is now planned for September 2025 and Artemis III for September 2026.

The OIG said NASA will spend $55 billion on the Artemis program by the time of Artemis II.

Artemis, named for Apollo’s twin sister in Greek mythology, is the most recent U.S. program to return astronauts to the Moon. Previous attempts fell victim to budget constraints and changing political environments. President Trump restored the goal of putting U.S. astronauts back on the Moon in 2017 (the Obama Administration eschewed the Moon, focusing instead on human trips to Mars in the 2030s) and in March 2019 Vice President Pence, as chair of the National Space Council, abruptly set 2024 as the target date. President Biden maintained that goal when he took office in 2021, but the date slipped to 2025 and then 2026.

Many are skeptical that even 2026 is possible.  Understanding what happened to the heat shield is only one of several issues identifed by the OIG as needing resolution before Artemis II can fly and Artemis III requires development of a Human Landing System to get astronauts from lunar orbit down to and back from the surface.

Liftoff of NASA’s Space Launch System (SLS) rocket with an Orion capsule on the Artemis I uncrewed test flight, Nov. 16, 2022. Photo credit: NASA/Joel Kowsky. SLS/Orion takes astronauts to lunar orbit, but Human Landing Systems are needed to get down to and back from the surface.

NASA’s Space Launch System rocket and Orion will get them only to lunar orbit, NASA is procuring HLS systems through Public-Private Partnerships with Elon Musk’s SpaceX and Jeff Bezos’s Blue Origin. SpaceX is under contract for the first two human landing missions, Artemis III and Artemis IV, using a lunar version of its Starship, which is still in development. The contract requires SpaceX to conduct an uncrewed test flight of Starship HLS before using it for a crew. NASA’s current Artemis manifest shows that flight in 2026, the same year as the Artemis III landing.

Source: NASA

Even if Starship HLS is ready for an uncrewed test flight less than two years from now, test flights often uncover unexpected problems, just like Artemis I did. The likelihood that the test flight, which requires refueling in Earth orbit, will be sufficiently flawless to convince NASA to put people on board just a few months later seems pretty low.

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