Several space agencies and private companies around the world have been ramping up their research and development in recent years, and they all have their eye on a single prize: Mars. There’s a massive fake Mars base underway in Dubai, researchers are heading to remote desert regions to simulate what it’s like on the Red Planet, and even NASA is testing how long-term spaceflight affects the human body. Elon Musk’s SpaceX is one of the companies not-so-quietly hammering away at the numerous hurdles that stand between mankind and a Mars colony, and during a talk at SXSW, Musk talked briefly about what life (and death) might be like for the very first Mars travelers.

The SpaceX founder explained how his company plans to begin traveling back and forth to Mars on a regular basis starting in 2019. The aim for humanity, Musk suggests, should be to colonize the Red Planet as fast as possible in case nuclear winter or an AI apocalypse wipes everyone out. In that event, residents of Mars would act as a sort of blueprint for rebuilding the human race. Still, it won’t be easy for the first Martians, and Musk makes that abundantly clear.

Shooting down the idea that traveling to Mars would be some kind of privilege reserved for the elite, the CEO made it very clear that traveling to the Red Planet wouldn’t be a vacation.

“For the people who go to Mars, it’ll be far more dangerous,” Musk told the crowd. “It kind of reads like Shackleton’s ad for Antarctic explorers. ‘Difficult, dangerous, good chance you’ll die. Excitement for those who survive.’ That kind of thing.”

At present, no space agency or private spaceflight outfit has anything resembling a Mars-suitable spacecraft. SpaceX’s Dragon is perhaps the closest, but the company has already made it clear that a Mars lander mission launched with a Falcon Heavy rocket (or some evolved version of it) would require an entirely new spacecraft. Plans for a “Red Dragon,” Mars-capable variant were shelved in 2017, and Musk revealed that the company was shifting its efforts to a larger ship.

The most optimistic timeline for a manned mission to the Red Planet puts its launch around 2030, but there’s still a lot of work to be done before such a thing is possible. A round-trip Mars mission would require passengers to remain away from Earth for as long as three years at a time. Thus far, the longest space stay is just shy of a year, and there’s no telling what curve balls the human body will throw after three years in space.