In Brief
If you're the CEO of a company that builds rockets, expect Elon Musk to factcheck your tweets. The SpaceX head has gone after United Launch Alliance CEO Tory Bruno after he compared Falcon Heavy to Delta IV Heavy.

Elon Musk is feeling confident following last week’s successful launch of the Falcon Heavy rocket. The SpaceX CEO took to Twitter to state that he would “eat his hat with a side of mustard” if the United Launch Alliance’s (ULA) upcoming Vulcan rocket is able to fly a national security spacecraft before 2023.