https://www.cnbc.com/2018/06/01/elon-musk-responds-to-boeings-claim-it-will-beat-spacex-to-mars.html

SpaceX billionaire Elon Musk clapped back to Boeing CEO Dennis Muilenburg's claim that Boeing will be the first space company to get to Mars.

"Do it," Musk tweeted Thursday in response to a story about the assertion.