About 25 years ago, journalist Stephen Petranek worked on a story for Life magazine. The image on the cover was of a pinkish sphere on a black background. Above it were the words “Our Next Home.” Just a few days before the issue was to be printed, Petranek was called in to talk to someone from corporate. The inquisitor had all of the pages of “Our Next Home” laid out in front of him, and Petranek worried that he was about to scuttle the whole thing.

Instead, he had a single question: “Could this possibly be true?”

Landing on Mars — and colonizing it — isn’t merely possible. “This is going to happen,” Petranek declares. And it’s going to happen soon, he adds, even though most people are probably as skeptical today as that corporate guy was decades ago. Space travel has become relatively inexpensive, and companies such as Elon Musk’s SpaceX are determined to make a Mars settlement a reality. With Petranek’s 2015 book, “How We’ll Live on Mars,” his goal was to deliver a wake-up call that we’re on the verge of one of the most significant events in human history.

It also turned into the basis for a script for National Geographic’s “Mars,” which debuted last month. (The final episode airs Dec. 19.) The miniseries blends documentary with science fiction. Interviews with experts explain present-day plans for Mars, while actors playing astronauts give viewers a sneak peek of the first manned mission to the Red Planet — which the show sets in the year 2033.

The following is based on a recent interview with Petranek; the transcript has been edited for clarity and length.

Q: What was your first reaction to this plan to adapt your book?

A: Early on, people said, “This can’t just be for nerds.” I thought, “Oh, no, they’re going to ruin it.” But they allowed me, encouraged me, to read every line of the script. They listened to me carefully about everything. It’s something entertaining, and it teaches you something.

I feel the accuracy of the fictional parts [is] so high that it’s not fiction. It might not be in 2033. It might be earlier. And the rocket might not look exactly like that. One thing nobody has right now is a rocket big enough to get to Mars. But when the astronauts are looking at control panels and see the amount of gravity coming into play, those numbers are calculated and real. Thrusters affecting the landing [in the first episode] — that’s a scenario NASA is worried about. Those spacesuits are actually up-to-date suits being used in Houston. The helmets look like motorcycle helmets because the spacesuit has an expandable band that fills in and creates a seal.

Q: How common are inaccuracies in most science fiction movies or TV shows?

A: I think they’re in almost all science fiction movies, even “The Martian,” which is based on really good science. There’s a lot that drives me nuts. A 300-mile-per-hour windstorm isn’t going to almost kill you. In the atmosphere on Mars, it’ll hardly push against you at all. [In “The Martian,” the main character, played by Matt Damon, is somehow impaled by flying debris from such a storm.] But I’m very grateful for “The Martian.” Before the movie, I gave a TED Talk on Mars. This talk was greeted with nice, polite applause. People were not excited. Half of the people didn’t believe it could be true. Now we’re getting the message across that by 2050, there might be 50,000 people on Mars.

Q: Why has going to Mars seemed so impossible to the public?

A: Part of it is because we didn’t continue to be a space-exploring species after Apollo. There was no particularly good reason to go to the moon. We proved we could do it. Then we didn’t do anything after that. In the 1970s, scientist Wernher von Braun was running around the halls of Congress saying, “I can get humans on Mars.” For at least 30 years, we’ve had the technology. All we did was fly 135 space shuttle missions with nowhere to go. We built the International Space Station, but we weren’t significantly exploring space. People got bored. The only time people paid attention to the space shuttle is when it killed a whole crew. It was supposed to be cheap and reusable, but it cost $1.4 billion every time it went up. We spent $150 billion. If we had one-fourth of that money, we would have had a viable outpost on Mars, and we would have had it for a while.

[Elon Musk unveils Mars colonization plan]

Q: What do you want people to think about as they watch “Mars”?

A: It doesn’t paint going to Mars as a vacation. That’s an accurate portrayal. But it will actually be a cool place to live and work. Also, there are amazing things from the big thinkers [a.k.a. the real-life experts interviewed]. Many meteorites that landed on Earth originated on Mars. One-celled critters could survive that trip. So one surprise that will occur to people is that the search for life on Mars could be related to our own existence. We still have no good explanation for how and why life formed on Earth.

Q: There’s disagreement about what we should do to Mars, right?

A: There are scientists who think we should treat Mars as a scientific park, so there’s some controversy around terraforming [or changing the planet to be more like Earth]. But Mars is a cold, dry rock in space with almost no atmosphere. It has a lot of water in the form of ice. To say we’d go to Mars and screw it up, the way we did with Earth, is nonsense. If we can give it an atmosphere, warm it up and have flowing water on the surface and make it a far more Earthlike planet, we’d be creating a garden out of a wasteland. On Earth, we treat our water and air as waste disposal. On Mars, we will have to learn to recycle everything.

It will help us tremendously to do that on Earth, too.

Q: Why is this the time to go to Mars?

A: I personally think people are beginning to think of space as not just the next big wilderness but also as an economic opportunity for humans. Now there are a lot of private rocket companies building serious rockets. It’s going private quickly. Elon Musk has hired hundreds of engineers to build a satellite communication system that may include 5,000 satellites. You only need to connect to a satellite and you get broadband Internet and telephone for anyone for far less than they’re paying now. Suppose he says, “I can give you that for $10 a month.” There are 2 billion cellphone users on Earth, so that would be $20 billion a month to SpaceX. That’s more than you need to get to Mars. I don’t see anything to stop it. It’s in humanity’s interest to have another planet to go to.