Billionaire entrepreneur Elon Musk is once again stirring controversy—this time by taking direct aim at the Head of NASA, Acting Administrator Sean Duffy.

The SpaceX founder launched a series of online attacks after Duffy announced that the U.S. space agency would reopen bidding for its multibillion-dollar moon lander contract, originally awarded to SpaceX for the upcoming Artemis III mission.

Read NASA’s Artemis Program overview here

Head of NASA Faces Musk’s Wrath

Musk took to his social media platform X (formerly Twitter) on October 21 to lash out at Duffy, mocking him as “Sean Dummy” and accusing him of trying to “kill NASA.”

The insult came after Duffy said in a televised interview that NASA may consider rival companies such as Blue Origin and Lockheed Martin to compete for lunar lander development.

The $4.4 billion contract was secured by SpaceX to develop its Starship megarocket.

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 It’s a towering 400-foot spacecraft designed to ferry astronauts to the lunar surface. Starship is also essential to Musk’s long-term goal of enabling human colonization of Mars.

“Sean Dummy is trying to kill NASA!” Musk wrote on X, referencing Duffy’s alleged proposal to fold the space agency into the Department of Transportation. In another post, Musk mocked Duffy’s past as a lumberjack sports champion, asking followers: “Should someone whose biggest claim to fame is climbing trees be running America’s space program?”

Read more on Reuters’ coverage of the Artemis program.

Duffy Responds: “The Race to the Moon Is ON”

While Duffy has avoided addressing Musk’s personal insults directly, he did issue a subtle but firm response online. Replying to Musk’s earlier boast that SpaceX was “moving like lightning compared to the rest of the space industry,” Duffy posted:

“Love the passion. The race to the Moon is ON. Great companies shouldn’t be afraid of a challenge. When our innovators compete with each other, America wins!”

The exchange has reignited discussions about competition in space exploration and NASA’s approach to partnerships with private companies. With China accelerating its lunar ambitions, President Donald Trump has reportedly urged NASA to achieve a U.S. lunar landing by 2029, before the end of his current term.

Head of NASA Search Heats Up 

Adding another layer to the tension, Musk also reignited his public campaign to see billionaire Jared Isaacman appointed as the next Head of NASA. Isaacman, who has led two private space missions with SpaceX, was once Trump’s preferred pick before his nomination was abruptly withdrawn earlier this year during a feud with Musk.

According to USA TODAY, NASA spokeswoman Bethany Stevens confirmed that “Secretary Duffy, in his capacity as acting NASA Administrator, is meeting with and vetting several candidates for the permanent role.”

Musk, however, left little ambiguity about his preference. Responding to investor Shaun Maguire’s post praising Isaacman, Musk replied with the “💯” emoji — a clear endorsement.

The Future of SpaceX and NASA’s Moon Program

As the Artemis III mission faces potential reshuffling, tensions between Musk and Duffy highlight the growing friction between public space programs and private aerospace powerhouses. Whether SpaceX retains its dominant position or faces new competition from Blue Origin and Lockheed Martin, one thing is certain — the race to the Moon is once again heating up.

Learn more about the SpaceX Starship program.