(CNN) - NASA is rethinking its reliance on SpaceX to land astronauts on the moon. Monday, Sean Duffy, the acting ...

Elon Musk is taking aim at the head of NASA amid news that the U.S. space agency may consider companies other than SpaceX to build lunar landers.

Musk responded with personal insults after Sean Duffy announced plans to seek proposals from Blue Origin and Lockheed Martin ...