President Donald Trump has congratulated Elon Musk's SpaceX for the successful launch of the Falcon Heavy rocket.

Musk replied, "An exciting future lies ahead."

Trump tweeted at the SpaceX and Tesla CEO on Tuesday after the launch of the Falcon Heavy (and its payload of a Tesla Roadster) from Kennedy Space Center in Cape Canaveral, Florida. 

It would have been a much more straightforward space-related moment for Trump than the time he looked directly into an eclipse without glasses.

Tweet may have been deleted

Tweet may have been deleted

It was a moment of rather mannerly camaraderie between the two — Musk and Trump have a rather complicated relationship. Before the 2016 election, the SpaceX founder told CNBC, "[Trump] doesn't seem to have the sort of character that reflects well on the United States."

Nonetheless, Musk was one of the many tech titans to attend a summit Trump held in Dec. 2016, alongside Apple’s Tim Cook, Facebook’s Sheryl Sandberg, Amazon’s Jeff Bezos, and Microsoft’s Satya Nadella, among others.

Musk served on the president's business advisory councils, but in June 2017 announced he was quitting after Trump pulled the U.S. from the Paris climate agreement.

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However, space exploration and interplanetary travel is obviously a priority for Musk, and Trump signed his first space policy in Dec. 2017, ordering NASA to return humans to the moon, then concentrate on Mars.

Guess who'll play a major part in this? Commercial space companies including SpaceX, already working toward Musk's ambitious Mars plans and successfully launching rockets like Tuesday's Falcon Heavy at a lower price point than other companies.

Trump and Musk's shared space ambition comes up even in Michael Wolff’s controversial 2018 memoir Fire and Fury: Inside the Trump White House, in which he describes a meeting between the pair in New York's Trump Tower.

“Elon Musk, in Trump Tower, pitched Trump on the new administration’s joining him in his race to Mars, which Trump jumped at,” Wolff wrote. A SpaceX spokesperson reportedly told Business Insider that this conversation indeed occurred but that “it wasn’t about Elon personally getting to Mars but rather making humans multi-planetary, which is the SpaceX mission.”

Mutually beneficial politeness it is then.