Ever since Elon Musk founded a start-up space company 14 years ago, the goal has always been the same: Establishing a colony on Mars. Now he’s finally beginning to reveal how he plans to get there.

Starting as soon as 2018, Musk’s SpaceX plans to fly an unmanned spacecraft to Mars. The unmanned flights would continue about every two years, timed for when Earth and Mars are closest in orbit, and, if everything goes according to plan, build toward the first human mission to Mars with the goal of landing in 2025, Musk has said.

But in an interview with The Post this week, Musk laid out additional details for the first time, equating the spirit of the missions with the settlement of the New World by the colonists who crossed the Atlantic Ocean centuries ago. And he acknowledged the immense difficulties of getting to a planet that is, on average, 140 million miles from Earth.

The months-long journey is sure to be “hard, risky, dangerous, difficult,” Musk said, but he was confident people would sign up to go because “just as with the establishment of the English colonies, there are people who love that. They want to be the pioneers.”

Before those pioneers board a rocket, though, Musk said the unmanned flights would carry science experiments and rovers to the planet. The equipment would be built either by SpaceX, or others. The early flights also would serve to better understand interplanetary navigation and allow the company to test its ability to safely land craft on Mars.

“Essentially what we’re saying is we’re establishing a cargo route to Mars,” he said. “It’s a regular cargo route. You can count on it. It’s going to happen every 26 months. Like a train leaving the station. And if scientists around the world know that they can count on that, and it’s going to be inexpensive, relatively speaking compared to anything in the past, then they will plan accordingly and come up with a lot of great experiments.”

The mission is all the more audacious in that SpaceX is a private company without the resources of a government agency. NASA has previously said it would provide “technical support” for the 2018 mission, though not financially, in exchange for what it said was “valuable, descent and landing data to NASA for our journey to Mars, while providing support to American industry.” NASA is planning its own manned Mars mission with the goal of landing in the 2030s. But some in Congress have indicated they are inclined to steer the agency back toward a moon mission first.

SpaceX's 2018 trip would use what the company calls its Dragon spacecraft boosted into space by Falcon Heavy, a massive rocket powered by 27 first-stage engines. When it flies for the first time later this year, it would become the “most powerful operational rocket in the world by a factor of two,” SpaceX says on its website. Falcon Heavy would have more than 5 million pounds of thrust at liftoff, or about the equivalent of 18 747 airplanes.

The rocket needs to be big. The Dragon spacecraft would become the largest object to land on the Martian surface “by a factor of 10,” Musk said. That would make it one of the most ambitious Martian landings ever attempted—and difficult. Of the 43 robotic missions to Mars, including flybys, attempted by four different countries, only 18 have been total successes. The latest, a NASA mission, delivered the unmanned Curiosity rover that is currently roaming the planet.