NASA delayed two astronaut missions to the moon, citing technical challenges that have emerged with everything from a spacecraft to new spacesuits.

The slips are a setback for the space agency’s Artemis program, which seeks to reinvigorate U.S. space exploration ambitions with a series of astronaut visits to the lunar surface in the coming years. The National Aeronautics and Space Administration aims to eventually establish a sustained U.S. presence on the moon and set the stage for missions to Mars.