NASA's Alan Stern talks Pluto ... and beyond

Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon.
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Growing up, Alan Stern couldn’t understand why NASA hadn’t sent a mission to Pluto. But after he became a planetary scientist, he quickly learned how arduous a task gaining approval for an exploratory mission to space can be. In the book “Chasing New Horizons,” Dr. Stern and coauthor David Grinspoon recount the decades-long saga of getting the New Horizons mission to Pluto and the outer solar system off the ground. “The whole project was about delayed gratification,” Stern says. The mission has been more than worth the wait. “There couldn’t have been anything more rewarding,” he says. The spacecraft’s flyby of Pluto in 2015 has already yielded major scientific breakthroughs, and scientists are still parsing through the images beamed back by New Horizons. The best may be yet to come as the spacecraft continues its journey through the Kuiper belt at the outer edge of the solar system. Now that New Horizons has made it to the Kuiper belt, Stern says that he and his colleagues are “the proverbial kids in the candy shop.”

Why We Wrote This

Pioneering spacecraft often get the credit for new discoveries made in space. But behind every mission to space are people – scientists and engineers – whose decades of work make those discoveries possible.

There were some tense hours at the operation center for the New Horizons mission when the spacecraft briefly lost contact with Earth on July 4, 2015, just days from its long-awaited flyby of Pluto. It’s just one of many gripping moments in a book that Alan Stern, the mission leader and a co-author of “Chasing New Horizons” along with astrobiologist David Grinspoon, describes as a “techno-thriller about how the farthest planet was explored.”

Dr. Stern recently sat down for an interview in his Boulder, Colo., office, surrounded by photos and mementos from the New Horizons mission – a mission that took decades to convince NASA to get off the ground and another decade to travel 3 billion miles to the last unexplored planet in our solar system. The New Horizons spacecraft continues to explore the vast reaches of the Kuiper belt, at the outer edge of our solar system. His responses have been edited for clarity and brevity. 

Q: What inspired you to become a planetary scientist?

Why We Wrote This

Pioneering spacecraft often get the credit for new discoveries made in space. But behind every mission to space are people – scientists and engineers – whose decades of work make those discoveries possible.

I got interested in part because I have a mind that is a scientific mind. But I remember being 8 or 12 years old and thinking, “If I could only grow up and work on this. This is important. This is the future.” 

When I grew up there was this interesting mélange of science fiction in movies like “2001: A Space Odyssey” and the television series “Star Trek” that were about this future in which humans were all over, in one case the solar system and in the other, the galaxy. At the same time, it was very clear that the beginning steps of that were taking place. People were going into orbit, and going to the moon, and space ships were being fired off at Mars and Venus and Jupiter and Mercury. And those two dots got connected by a lot of kids, that there was a real thing going on and you could see where it was going in the distant future, and like myself, a lot of people were just intoxicated by that cocktail of reality and the future projection.

Q: What was it like having Pluto, and New Horizons, dominate your career for so many decades? 

There couldn’t have been anything more rewarding. To be on a first mission – it’s what planetary scientists live for. We got to run anchor leg in a 50-year relay. I often say, “Look at that, the solar system saved the best for last.”

Q: What findings from the mission stand out?

I always say there are three things, two scientific and one otherwise. There were the meta-results showing that small planets can be as complex as big ones. And all the textbooks would have told you Pluto will be geologically inactive. But instead Pluto is actually highly geologically active.

The third thing we discovered was how much it affected people. None of us on New Horizons expected the kind of public response and the personal stories of how it changed some lives. In the book we called it a final discovery. The last words of the book are David and I saying, we think this is more important than everything else that we did.

Southwest Research Institute
Alan Stern is the principal investigator of the New Horizons mission to Pluto.

Q: What do you think about Pluto’s “demotion” from planet status by the International Astronomical Union? 

It’s wrong scientifically, and I call it pure “BS” – bad science. It was very hurtful to a lot of people on the team because what we worked on very hard was made the subject of jokes, and we thought we were doing this Olympian thing. But by the time it was all done I don’t think it mattered; virtually no one who does research on Pluto calls it anything but a planet.

Q: How do you weigh the scientific use of a mission against the pure exploratory value?

It boils down to the tension between your head and your heart. And they’re not mutually exclusive. The fact that this had both made it all the better.

When I was growing up as a little kid and I’m watching human space flights and first missions to everywhere, I thought it seems so obvious, why would you not finish what you started, why would you leave one planet left? Just for the exploration.

Then here I am getting out of graduate school and I find out that no, it has to have a scientific case, it has to pass muster at these formal levels.

For the first mission, it seemed to me like the exploration value alone was sufficient. But it wasn’t. So we had to win it on both fronts. And it was even harder because it was far away, and a lot of people wanted to do things that would yield more immediate returns.

Q: What do you see as the next big space exploration? 

We’ve hardly scratched the surface. There will be new missions to the Kuiper belt, either to other planets in the Kuiper belt or to go back to Pluto. At the same time, the field is very interested in the next stage of Mars exploration. That will include sending humans and things you can’t do with robots.

We’re developing this whole ocean worlds initiative. There’s already a mission to [Jupiter’s moon] Europa, and we’re looking at other ocean worlds.

The planetary program at NASA is currently in a golden age. I think we were some bit of help to that, and lot of other missions were, too.

Q: What was it like being on a mission that took 10 years from launch to Pluto flyby? 

We knew what was waiting at the other end of the line, and we couldn’t wait to get there. The whole project was about delayed gratification. But the mission just physically, even if it had been trivial to get it started, it still would be one of these things where you fire it, and you have to go to the far end, to the frontier, to start. Then the Kuiper belt mission – that’s from 2016 to 2021, and probably will go another few years until we pass out of the Kuiper belt – that’s what we came to do. That’s what we built this for. That’s what we fought to get it for. So now that we’re there, it’s like being the proverbial kids in the candy shop.

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