(The Center Square) – NASA's return to the moon is unlikely to happen in 2025 as planned because of delays and challenges in building the lunar lander and space suits needed for the mission, according to a report from a Congressional watchdog. 

The U.S. Government Accountability Office reported that NASA's timeline for the Artemis mission was "unrealistic."

"The complexity of human spaceflight suggests that it is unrealistic to expect the program to complete development more than a year faster than the average for NASA major projects, the majority of which are not human spaceflight projects," according to the report. "GAO found that if development took as long as the average for NASA major projects, the Artemis III mission would likely occur in early 2027."

NASA did not immediately respond to a request for comment on the Artemis timeline.

NASA is projected to spend $93 billion on the Artemis effort up to fiscal year 2025, according to a 2021 report from NASA's Office of Inspector General. But the exact cost is unknown. That same report noted that "NASA does not have a credible estimate that consolidates all Artemis costs across mission directorates."

In the fiscal year 2024 President's budget request, NASA asked for $12.4 billion over 5 years for the human landing system and modernized space suits.

The Government Accountability Office report cited delays to the Human Landing System program were a factor. The Human Landing System program had delayed eight of 13 key events by at least 6 months as of September 2023. Two of those events were been delayed to 2025, the year the lander is planned to launch. The delays were caused in part by the Orbital Flight Test. The test was delayed by seven months to April 2023. It was then ended early when the vehicle deviated from its expected trajectory and began to tumble. Subsequent tests rely on successful completion of a second Orbital Flight Test.

There also is a lot of other work that needs to be done before the moon mission, including by government contractors such as SpaceX and Axiom.

"SpaceX must complete a significant amount of complex technical work to support the Artemis III lunar landing mission, including developing the ability to store and transfer propellant while in orbit," according to the report. "A critical aspect of SpaceX's plan for landing astronauts on the moon for Artemis III is launching multiple tankers that will transfer propellant to a depot in space before transferring that propellant to the human landing system. NASA documentation states that SpaceX has made limited progress maturing the technologies needed to support this aspect of its plan."

Axiom might have make changes to the space suits for the mission.

"NASA's original design did not provide the minimum amount of emergency life support needed for the Artemis III mission," according to the report. "As a result, Axiom representatives said they may redesign certain aspects of the space suit, which could delay its delivery for the mission."

NASA plans to return U.S. astronauts to the surface of the moon by the end of 2025. The mission, known as Artemis III, will be the first time that astronauts will land on the moon since the Apollo 17 mission in 1972. And it will be the first time ever that crew will land at the south pole of the moon. The Artemis III mission is part of series of missions "to maintain U.S. leadership in space exploration, build a sustainable lunar presence over the next decade, and ultimately travel to Mars," according to the report.

In March 2019, President Donald Trump's White House directed NASA to accelerate its plans for a lunar landing from its original goal of 2028 to 2024, in part to create a sense of urgency in returning American astronauts to the moon. In November 2021, NASA announced that it was no longer working to its goal of an Artemis III lunar landing in 2024 and that the new date would be no earlier than 2025.