NASA’s efforts to return astronauts to the moon have been delayed — again.

The agency announced Tuesday that its next Artemis mission, which was to send four astronauts on a flight around the moon in a next-generation capsule, will launch in September 2025 rather than later this year.

A subsequent mission to actually land astronauts on the lunar surface near the moon’s south pole will be delayed to September 2026.

NASA said the two flights are being pushed back to allow enough time to test new technologies on the Orion spacecraft for crewed moon missions.

“We are returning to the moon in a way we never have before, and the safety of our astronauts is NASA’s top priority as we prepare for future Artemis missions,” NASA Administrator Bill Nelson said in a statement.

The extra time will also give teams the chance to finish investigating and troubleshooting issues that cropped up during the first uncrewed Artemis test flight that took place in late 2022, according to NASA. Those outstanding investigations include a battery issue and problems with components related to the Orion capsule’s air ventilation and temperature control systems, the agency said.

“Artemis is a long-term exploration campaign to conduct science at the moon with astronauts and prepare for future human missions to Mars,” Amit Kshatriya, deputy associate administrator of Exploration Systems Development at NASA Headquarters, said in a statement. “That means we must get it right as we develop and fly our foundational systems so that we can safely carry out these missions.”

The latest setback follows years of holdups and budget overruns with NASA’s Artemis program. The agency has spent more than $42 billion over more than a decade on developing its new Space Launch System megarocket and Orion spacecraft to take astronauts back to the moon.

Last year, NASA’s Inspector General released a report outlining the challenges around the enormous price tag and ambitious schedule for the Artemis program. The report estimated that each Artemis launch would cost an estimated $4.2 billion, making the lunar missions difficult to sustain alongside the agency’s other exploration goals.

This is a developing story. Please check back for updates.