In “When the Heavens Went on Sale,” Ashlee Vance surveys what he calls the Wild West of aerospace engineering. Such ventures no longer require governmental approval or vast personal wealth, he writes; it’s easier than ever for an entrepreneur to launch a rocket or send a satellite into orbit. His exuberant book crisscrosses the world to follow the development of four companies: Planet Labs, Rocket Lab, Astra and Firefly. “Writing a book like this is dangerous,” Vance allows, because conditions are likely to change overnight.

It’s a risk he’s encountered with his past work: His last book, a best-selling biography of Elon Musk, was the first up-close portrait of the entrepreneur when it was published in 2015. We spoke on May 11, just before Musk announced that there would be a new chief executive at Twitter — and several days before he compared George Soros to a fictional Jewish supervillain. Whatever has unfolded in the years since Vance wrote his biography, he argues that people have a “simplistic view” of Musk — though he too has his misgivings about the billionaire’s recent choices.

This conversation has been edited for length and clarity.

Q: What made you interested in telling the story of this slice of the space industry?

A: With all this attention on billionaires and space tourism, I thought the public was missing a huge chunk of the real story — which is that most of the money and activity is directed towards building this economy in low Earth orbit. Commercial space has been this thing people have been chasing for decades, and it’s had a lot of false starts — and then all of a sudden in the last five years, it’s happening. I just do not think the average person knows how dramatically things have changed and how far they’ve already gotten. So often with these big tech changes — social media, for example — by the time the public sort of wakes up to what’s going on, it’s too late.

Q: Are there risks or consequences that we should worry about? My understanding from pop culture is the “Gravity” scenario — where one thing that gets knocked off course can crash into everything else, and it just becomes a disaster.

A: Which is real, you know? We’re building all this new stuff, but there are things like GPS that are already up there that could be disrupted — and GPS is like the glue that holds our smartphones and the modern world together. For better and quite possibly worse, this is new territory that is actively being conquered. There is some regulation, but it’s not really keeping up with the times.

On the whole, my book has an optimistic tone, because the immediate stuff that’s come out, I think, is quite beneficial to the world. If we are actually going to address climate change, there’s things about our planet that I can’t see being solved any other way. Planet (Labs) can actually look out in the world and see what’s happening to our forests: How much carbon dioxide are these trees actually sucking down? Is somebody illegally cutting down parts of that Amazonian rainforest? And if we’re to put metrics around things like carbon credits and stuff like that, the only way to do that is from space. So, yes, we could screw this all up and make this place unusable — but we will for sure be able to analyze and understand our world better than ever before.

Q: You write that not only do you feel confident the commercial space industry will grow, it will profoundly change the world: “This is the nature of technology and of the human spirit when offered a new playground.” What makes you feel so confident about this playground?

A: I do argue there is what I call this “shared hallucination” around space. Rockets are one of the worst businesses you can possibly be in: no money, extremely high risk. All the money is in satellites. But you still see these venture capitalists, even though there are already 10 small rocket companies, who are like, “I want one of my own” — because there’s this excitement that comes with it. There’s this irrational exuberance.

I think we’re 100 percent going to make a go of this. But something else has to come along, new ideas have to come along, to really make all of these business cases check out. The people that look like winners right now might not be the ones that stick around for the duration. It really reminds me of the consumer internet in 1996 — though this probably comes with more doubts and higher risks.

Q: I want to ask about your last book, about Elon Musk. Some reviews at the time called it borderline hagiographic. Obviously, a lot has happened since then, with Musk’s acquisition and management of Twitter. Have any of those intervening events made you reassess how you depicted him?

A: It’s funny because half the people who read it say I was too nice, and half the people who read it say I was too mean, and so I feel like it ended up in a good place. Nobody had ever uncovered anything, really, about him before. I was not shy about sharing how difficult he is to work for, his interpersonal issues.

He was just a different sort of figure when that book was ending. Obviously, in the intervening years, he’s let (laughs) the full Elon loose on the public and has also gotten much more involved in politics, which he stayed away from in the past. I love the book because I think it captures this moment in time and the reality of the moment. But yeah, things have totally changed.

People have this very simplistic view of him, and he has himself to blame for some of it — for most of it. But it seems like people either love him or hate him. He’s almost like a religious figure: Do you believe in him or not? I understand where it comes from; I just find it really silly, because if you talk to him in person — like any human, he’s extremely nuanced and complicated and not at all like some caricature. When you talk to him in person, he’s nothing like his Twitter self, either. He’s actually very thoughtful. (laughs) So anyway, yeah, I think it’s funny — he’s become this caricature.

Q: Part of the thesis of the book was that, at a time when it felt like there was no more interest or energy in physical innovation or engineering, he was interested in those things — in cars and rockets. And now it seems like he’s interested in culture wars. From your perspective as a biographer, was that an unexpected turn?

A: The Twitter thing really threw me for a loop. It was quite surprising. (laughs) SpaceX has just been this thing that was calling in his soul for so long, and I always expected that, over time, he would gradually pull away from more and more stuff until he was just working on SpaceX full time. And it seems like he’s spending most of his time at Twitter and engaging in all of these political battles.

I’m trying to find the right word. You know, I don’t — love where it’s ended up. I think it’s a waste of his talents. I think Twitter is generally more frivolous than he seems to think. Everything he does has this humanity-level theme to it. This time he’s picking freedom of speech. I just don’t know that ... how to put it? I think his talents are much better served elsewhere. I don’t think this is his strongest suit.

Q: The risk you take, that any writer takes, when you’re capturing someone is that they can change.

A: I think Elon’s a one-of-a-kind character. We’re not used to having the world’s richest person just living out their life in public, doing hand-to-hand combat with people, you know?