NASA delays Artemis II to April 2026, discloses root cause of heat shield issue

Today, December 5th, NASA announced that the Artemis II mission will be delayed to April 2026. Due to the new delay for the next Artemis mission, the first landing mission, Artemis III, has been delayed to mid-2027.

This mission delay announcement was shared at a press conference at NASA Headquarters with the following speakers:

• NASA Administrator Bill Nelson
• NASA Deputy Administrator Pam Melroy
• NASA Associate Administrator Jim Free
• Amit Kshatriya, Deputy Associate Administrator, Moon to Mars Program Office, Exploration Systems Development Mission Directorate
• Reid Wiseman, NASA astronaut and Artemis II Commander

The decision to delay Artemis II to 2026 is due to the results of the Artemis I heat shield issue investigation. That investigation identified the technical cause of unexpected char loss across the spacecraft’s heat shield. This delay is the second for Artemis II within twelve months, that delay saw the mission move from November 2024 to September 2025.

Artemis II will fly with the same heat shield technology used on the previous mission but will instead opt to use a different atmospheric reentry trajectory.

Speaking on the delay, NASA Administrator Bill Nelson said the following:

“The Artemis campaign is the most daring, technically challenging, collaborative, international endeavor humanity has ever set out to do,” – “We have made significant progress on the Artemis campaign over the past four years, and I’m proud of the work our teams have done to prepare us for this next step forward in exploration as we look to learn more about Orion’s life support systems to sustain crew operations during Artemis II. We need to get this next test flight right. That’s how the Artemis campaign succeeds.”

Adding onto Administrator Nelson's comments, Catherine Koerner, Associate Administrator for Exploration Systems Development Mission Directorate, via an official press release stated:

“Throughout our process to investigate the heat shield phenomenon and determine a forward path, we’ve stayed true to NASA’s core values; safety and data-driven analysis remained at the forefront,” – The updates to our mission plans are a positive step toward ensuring we can safely accomplish our objectives at the Moon and develop the technologies and capabilities needed for crewed Mars missions.”

Artemis II Commander Reid Wiseman added that the Artemis II crew are excited to fly their mission along with being thankful for NASA's willingness to weigh all options and make decisions in the best interest of safety for human spaceflight.

The Artemis II mission will be the first crewed mission beyond low Earth orbit since Apollo 17 in 1972, spending a planned ten days in space. The mission will utilize NASA's Space Launch System rocket to carry NASA astronauts Reid Wiseman, Victor Gloover, Christina Koch, and Canadian astronaut Jeremy Hansen around the Moon inside the Orion spacecraft.

Stacking of the Space Launch System vehicle that will be used for the mission is currently underway at the Kennedy Space Center inside NASA's Vehicle Assembly Building, in Florida. Stacking began on November 20th with the bottom segment of the left side solid rocket booster, by December 1st the right side bottom segment was also stacked. Stacking is expected to take approximately four months, from the first solid rocket booster segments to the Interim Cryogenic Propulsion Stage, all hardware is believed to be at the Kennedy Space Center.

Issue with Orion's heat shield

Today's announcement also had NASA finally disclose the root cause of unexpected material loss across the Artemis I Orion capsule heat shield.

NASA engineers determined that as Orion was returning through the atmosphere from its first mission around the Moon gases generated inside the heat shield’s ablative outer material, called Avcoat, were not able to escape and dissipate as expected. This caused pressure to build up and cracking to occur, causing some charred material to break off in unexpected areas.

Prior to Artemis I, ground tests used higher heating rates than in flight, allowing the char layer to form and ablate as expected. However, recent upgrades to NASA's arc jet facilities have allowed researchers to replicate the actual Artemis I reentry conditions, confirming the cracking behavior observed during flight. Despite the char loss, the heat shield outperformed expectations by keeping cabin temperatures within acceptable limits. Flight data showed that if the mission had been crewed, astronauts would have been safe.

With a deeper understanding of the interaction between materials and reentry conditions, NASA is confident in the Artemis II heat shield’s safety. Operational adjustments during reentry will further ensure the safety of future missions, reinforcing the agency’s flight rationale for crewed exploration.

NASA's full findings, research process, and future advancements for Orion's heat shield can be found here.

Beating China

NASA Administrator Bill Nelson also made several remarks regarding China's efforts to land on the Moon this decade, those familiar with the program believe that a landing could come as soon as 2028. Hardware for the spacecraft and rockets needed is currently being tested ahead of test missions in the coming years.

Nelson argued that the U.S. must land first so it can set the standards regarding the use of lunar resources through the non-binding Artemis Accords, specifically those around the Moon's south pole. The administrator is particularly worried that China may establish no-fly zones around its lunar equipment in possibly resource-rich areas, the U.S. has been trying to establish no-fly zones near Apollo hardware since 2011.

In the long term, NASA plans to conduct one lunar surface mission per year using the Space Launch System rocket, the Orion spacecraft, and a commercial lunar lander. China plans to conduct two missions per year using the Mengzhou spacecraft, the Lanyue lunar lander, and the Long March 10 launch vehicle, of which two will be needed per landing mission.