The billionaire used an offensive word for people with intellectual disabilities while lashing out at Danish astronaut Andreas Mogensen.

Andreas Mogensen, a Danish astronaut who previously was the ISS commander until March of last year, called out Musk over his comments during his interview with Sean Hannity this week, where Musk said they were accelerating the return of the two astronauts, and claimed they were left in the ISS “for political reasons.”