NASA's top official on Monday said the U.S. space agency was opening up the contract for its Artemis 3 moon mission to compete against SpaceX, which he said was running behind schedule.

Acting NASA chief Sean Duffy and billionaire Elon Musk on Tuesday traded barbs online over who should lead the space agency, a day after Duffy invited companies to compete with Musk's SpaceX for a moo...

The calling for new rivals represents a paradigm shift in NASA’s lunar strategy.