SpaceX CEO Elon Musk is aiming to start a Martian colony within the next decade, but another rival CEO says his company will actually be the one to put humans on the Red Planet first. Boeing CEO Dennis Muilenburg recently answered questions at the "Whats Next" tech conference in Chicago, and when asked about the future of his company, he focused on breakthroughs in space travel. "I’m convinced that the first person to step foot on Mars will arrive there riding on a Boeing rocket," said Muilenburg, according to Bloomberg.

"The first person to step foot on Mars will arrive there riding on a Boeing rocket."

Boeing has been in the space business for decades, as it has been one of NASA’s primary contractors since the space agency’s inception. The company built the first stage of the Saturn V rocket — which took astronauts to the Moon — and it has since contributed to the Space Shuttle program and crafted many elements of the International Space Station. Currently, Boeing is designing and developing the Space Launch System, the massive rocket that NASA wants to use to send people to Mars. So when Muilenburg says the first people will get to the planet with a Boeing rocket, he’s most likely referring to the SLS.

If that’s the case, his comments seemingly cast doubt on Musk’s ambitious timeline for getting to Mars. Last week, Musk detailed his vision of sending huge passenger spaceships, filled with 100 colonists each, over to the Red Planet to start a self-sustaining colony. But Musk has no intention of waiting to get his settlement started. He’s aiming to send the first crewed spaceship to Mars by 2024. Meanwhile, NASA is targeting a human Mars mission for the mid-2030s, about a decade after SpaceX says it will start sending people over to the planet. If Muilenburg thinks Boeing will get to Mars first, that means he doesn’t have much confidence in Musk’s estimates.

An artistic rendering of NASA's Space Launch System. (NASA)

SpaceX has a history of missing its very optimistic deadlines. Musk boasted in 2011 that his company would send people into space within the next three years. Five years later, it’s now looking like those first human flights may not happen until 2018. And SpaceX promised to launch its Falcon Heavy for the first time in 2013 or 2014; that debut flight has been pushed back again and again.

Of course, the circumstances surrounding the two company’s Mars initiatives are very different. Boeing is receiving billions in funding from NASA to develop the SLS. SpaceX is self-funding its Mars vehicles for now, though the company does receive federal funding through other unrelated NASA contracts. Currently SpaceX is only devoting 5 percent of its resources to building its Mars rockets and spaceships, though it hopes to get more help from public and private partnerships in the future.

Since no one has even come close to sending people to Mars yet, it remains to be seen which company has a better chance of actually getting to the Red Planet. Hopefully we’ll find out the winner in the next decade or so.

A look at SpaceX's Mars colonization plans