Kenneth Chang reported this article from NASA Headquarters in Washington, D.C., and covered the Artemis I moon launch in 2022.
NASA on Thursday postponed a mission to send four astronauts around the moon and back to Earth until April 2026.
The move is the latest setback for Artemis, the government space agency's return-to-the-moon program, which has already faced years of delays.
A subsequent mission to land astronauts near the south pole of the moon is now scheduled for mid-2027, Bill Nelson, the NASA administrator, said during a news conference on Thursday.
The adjustment to the Artemis schedule comes as the Mr. Nelson prepares to leave the agency when President-elect Donald J. Trump returns to the White House in January.
Even though Mr. Trump had set the goal of sending astronauts back to the moon during his first administration, he could change his mind after he takes office. In the coming months, NASA could instead put more money toward another destination that Mr. Trump has talked about: Mars.
The first of the two missions that were delayed on Thursday, known as Artemis II, is set to be the first in more than 50 years to send astronauts close to the moon. It will also be first time that astronauts launch on top of NASA's giant new Space Launch System rocket and then swing around the moon inside a crew capsule called Orion before returning to Earth and splashing down in the Pacific Ocean. The mission will not land on the moon.
The Artemis II crew will consist of three NASA astronauts -- Reid Wiseman, Victor Glover and Christina Koch -- and one Canadian astronaut, Jeremy Hansen.
A previous, uncrewed mission that circled the moon in 2022, known as Artemis I, was largely successful. NASA officials were hopeful that Artemis II would launch late this year.
But in January, NASA officials announced that Artemis II had been pushed back by at least nine months, to September 2025. They cited a slew of technical issues behind the delay, including concerns about electronics in the astronauts' life support system inside Orion and continuing analysis of unexpected damage to Orion's heat shield during Artemis I.
The puzzle of the damage to the heat shield -- which is critical to protecting the astronauts as they re-enter Earth's atmosphere -- proved particularly arduous to decipher. Months of engineering investigations delayed preparations for Artemis II.
The country's current moon program started in December 2017 when President Trump directed NASA to send astronauts back to the moon, a place they had not stepped since the Apollo 17 mission in December 1972. Under President Obama, NASA focused on sending astronauts to new destinations like an asteroid and eventually Mars. The Biden administration largely continued the Trump administration's approach.
With Mr. Trump returning to the White House next month, the direction of the Artemis program that he started may shift. Mr. Trump has been leaning on the counsel of Elon Musk, the billionaire founder of SpaceX, which is building a version of its Starship spacecraft to be used as the lander for the Artemis III mission.
On Wednesday, Mr. Trump announced that he would nominate Jared Isaacman, the chief executive of Shift4 Payments, a payment-processing company, to serve as the next NASA administrator. Mr. Isaacman, a close associate of Mr. Musk, previously led two private missions that launched on SpaceX.
The Space Launch System and Orion capsule are expensive and the first four Artemis missions are expected to cost more than $4 billion each, the agency's inspector general estimated. Mr. Isaacman could steer NASA toward using SpaceX's Starship spacecraft not only as the lander to take the astronauts from lunar orbit to the moon's surface, but also to provide transportation from Earth to the moon.
Mr. Trump could also choose to focus on Mars, the primary intended destination of Mr. Musk for the Starship vehicle.
"With the support of President Trump, I can promise you this: We will never again lose our ability to journey to the stars and never settle for second place," Mr. Isaacman said in a posting on the social media site X on Wednesday.
He added, "Americans will walk on the Moon and Mars and in doing so, we will make life better here on Earth."
This is a developing story.