There’s no question about it, it’s an exciting prospect: SpaceX CEO Elon Musk is looking to send real human beings to Mars to begin colonizing our neighbor. But it has one very dark side to it: the people going there are going to die there.

Musk, who recently made the comments at the International Astronautical Conference in Mexico, said it is a necessity that mankind become a multi-planet species in order to survive, as it is only a matter of time before an extinction event wipes out civilization on Earth. That’s why he’s helping to spearhead an ambitious new project to send mankind to Mars.

Musk is looking to build a massive rocket with 42 engines that would send entire colonies to the Red Planet. But we still don’t even know just how possible that is, and how mankind would survive on the planet.

Scientists have envisioned pressurized plexiglass domes with green plants and grow lights, but we haven’t figured out how to build those here on Earth, let alone on Mars.

Mars is certainly a far cry from Earth. The average temperature on the planet is negative 80 degrees Fahrenheit, and at its warmest temperatures reach a balmy 68 near the equator but plunge to negative 100 at night. Mars just doesn’t have Earth’s dense atmosphere, which is what results in the huge temperature fluctuations and massive dust storms.

Mars also lacks a magnetic field, which means there’s nothing to shield inhabitants from the intense radiation that is blasted out by the sun. It would be like living in the midst of Chernobyl shortly after the nuclear power planet meltdown. Basically, living on Mars would be like living in a bunker after a nuclear apocalypse.

And going there will be pricy. Trips are estimated to cost about $10 billion per seat, although Musk is trying to drive that down to just $200,000.

But the question is, why on Earth would someone sign up for this? Musk thinks it appeals to some people’s sense of adventure. After all, America was founded by pioneers who braved some of the worst conditions imaginable first to cross the Atlantic Ocean to get there, and then to cross the entire country to the Pacific. Mars can be considered the next “New World” in that regard.