Return home could be the most dangerous part of the mission for Artemis-2 astronauts
The flight around the Moon passed without serious problems, but the main test for the Artemis-2 crew is still ahead – the return to Earth. It is at this moment that the Orion spacecraft will encounter extreme temperatures upon re-entry into the atmosphere.
Technicians inspect the Artemis-2 heat shield at NASA's Kennedy Space Center in Florida, 2020. Photo: Isaac Watson / NASA
The New York Times provides the details.
The heat shield is a key safety element of the Orion spacecraft. It protects the spacecraft and astronauts from infernal temperatures during re-entry into Earth's atmosphere. If it fails, the metal structure could melt and disintegrate, leaving the crew with no backup option or possibility of evacuation.
NASA is confident in the mission's safety. According to agency management, numerous tests and simulations have shown that, even with some imperfections, the heat shield provides a sufficient margin of reliability. Astronauts are expected to return to Earth at a speed of approximately 38,600 kilometers per hour after a ten-day journey.
However, as The New York Times writes, not all experts share this optimism. Former NASA astronaut and heat shield specialist Charlie Camarda believes that the launch of Artemis-2 was a mistake.
In his opinion, the agency does not sufficiently understand the risks. He estimates the probability of a successful return at 95%, but this means a risk of catastrophe of about 1 in 20. For comparison: the International Air Transport Association estimates the chances of dying in an airplane crash at approximately one in nine million.
The main problem lies in the lack of precise knowledge. During the uncrewed Artemis-1 mission in 2022, the capsule successfully returned, but after its recovery from the ocean, it was discovered that the heat shield was damaged: it had cracks and missing pieces of material.
Technicians inspect the Orion heat shield as part of a post-flight analysis. Photo: NASA
The investigation showed that gases accumulated inside the shield, made of Avcoat material (similar to what was used in the Apollo program more than 50 years ago). These gases created pressure and caused a sudden delamination of the material instead of its gradual and uniform ablation. For future missions, the material's formula was changed, but for «Artemis-2», the shield had already been manufactured using the old technology and installed.
Replacing the shield or the entire capsule would mean a significant launch delay. Therefore, NASA chose a different path – to alter the re-entry trajectory: making it steeper and shorter to reduce the duration of exposure to high temperatures. If the Artemis-2 heat shield performs no worse than during the Artemis-1 mission, the astronauts will splash down in the Pacific Ocean without issues.
In NASA's history, there are two tragic dates: January 28, 1986, when the Challenger shuttle disintegrated 73 seconds after launch, and February 1, 2003, when the Columbia shuttle broke apart upon re-entry from orbit.
In both the Challenger and Columbia cases, warning signs appeared during previous flights. But management reassured themselves that past missions concluded without disasters, instead of urgently addressing problems that later led to the loss of their crews.
Pictured right: the crew capsule of the Orion spacecraft, which is set to return the astronauts to Earth during the Artemis-2 mission. Photo: NASA
Could cracks on the Artemis-2 heat shield form and spread at a catastrophic rate?
As part of additional checks, NASA simulated even the worst-case scenarios — the formation of cracks, the delamination of entire material blocks, and accelerated heating. According to these calculations, even under such conditions, a sufficient portion of the shield should remain intact, and the internal carbon fiber and titanium structure will be able to maintain the integrity of the crew compartment until the end of the descent.
After these checks, some independent experts changed their stance and acknowledged that the risks have been reduced to an acceptable level.