Establishing a colony on Mars would protect the long-term survival of the human race. At some point, we’re going to need to become a spacefaring species. There’s no better time than now to get started.

Stephen Petranek is a journalist and author of a new book titled How We’ll Live on Mars. Fittingly, he’s here to tell us not just how we’ll live on Mars, but also why and when. The why? As mentioned, we need to get off this rock sooner or later. The when? Within 15 years.

Stephen Petranek: The reason we need to travel to Mars and to establish a civilization on Mars is to protect the long-term survival of the human species. We need to become a spacefaring society and eventually we need to move far beyond Mars — not only from our own solar system, but into other solar systems within this galaxy and other solar systems in other galaxies. We are making wonderful progress finding other Earth-like planets and we will continue to find many of those in the future.

Eventually the human species is going to disappear. That means everyone who’s a human being will die eventually and this species will die out and go extinct. And there are a number of reasons how that could happen and why that could happen including a large asteroid hits Earth and destroys everything larger than a rabbit as happened in the age of the dinosaurs 65 million years ago or eventually our sun begins to die and that is a 100 percent probability our sun will begin to die in about 2 billion years. And one of two things will happen. Either Earth will be thrown completely out of its orbit and go spinning off into space and everyone will die very quickly. Or the sun will essentially irradiate Earth as it expands because what happens with a dying sun is it gets very large. And so in order to survive as a species we have to become a spacefaring species. We have to get off this planet eventually and that is the long-term hope for humanity.

Mars is the most habitable place in our solar system by far. And even though it’s an incredibly hostile environment, we’ve developed the technology over the last 50 years to survive on Mars and to survive quite readily. So Mars is a wonderful first step. It’s where we go to learn how to go farther. Elon Musk says he will land on Mars in 2025. We’ve had, he and I have had a number of — several conversations about this. He’s more optimistic than I am and he’s one of the most optimistic people I’ve ever met. I’m very optimistic, but he’s more optimistic than I am. So I am in the discussion with him about a timeframe and when a SpaceX rocket or two might land on Mars. We kind of came to the conclusion that maybe we should say 2027. In other words, give him a two-year fallback. But he specifically says and I quote him on this in the book that he will be extremely disappointed if a SpaceX rocket has not landed on Mars by 2030. And I think that’s quite reasonable. I’d give 90 percent odds to a betting person that a SpaceX rocket will land on Mars before 2030.