SpaceX CEO Elon Musk said on Thursday that the rocket manufacturing company intends to offer a trip to Mars to anyone who volunteers in the future but warned that the journey might be uncomfortable.

What Happened: “In all seriousness, SpaceX hopes to offer travel to Mars to anyone who wants to go…” Musk wrote on social media platform X in response to former European Union Commissioner Thierry Breton with whom he has a history of sparring now and then.

However, the journey to Mars, Musk warned, will be like a “long sea voyage.”

“….it will be like a long sea voyage in centuries past – dangerous and uncomfortable, but great adventure!” Musk said.

Musk aims to take humans to Mars with SpaceX’s Starship launch vehicle in an attempt to “make life multi-planetary.” Musk has previously even envisioned a self-sustaining city on Mars called Terminus.

Why It Matters: Earlier this month, Musk said the first Starships will head to Mars in two years once the next Earth-Mars transfer window opens.

The first launches to Mars in 2026, Musk then said, will not have a crew onboard and will be aimed at testing the flight’s ability to land intact on Mars.

“If those landings go well, then the first crewed flights to Mars will be in 4 years,” Musk wrote, pegging the first crewed Starship flights to the neighboring planet for 2028. A self-sustaining city, he said, should be ready in about 20 years.

Starship, however, is still under development and undergoing test flights. It was last launched in June and the company is now awaiting the green light from the Federal Aviation Administration for its fifth flight test.