FILE PHOTO: NASA announces the crew of the Artemis II space mission, in Houston

Astronaut Joseph M. Acaba speaks at an NASA event during which the crew of the Artemis II space mission to the moon and back is announced in Houston on April 3, 2023.

WASHINGTON — NASA on Tuesday added more delays to its Artemis moon program, scheduling for 2026 its first astronaut lunar landing in half a century while spacecraft from Elon Musk’s SpaceX, Lockheed Martin and other contractors face development challenges.

The space agency’s first two Artemis missions involving astronauts were each pushed back nearly a year in delays designed “to give the Artemis teams more time to work through the challenges,” NASA administrator Bill Nelson told reporters in a news conference.