Dean chats with Alan Stern, a planetary scientist for the New Horizons mission exploring Pluto. Listen for the latest on the mission, and behind the scenes audio from the I Heart Pluto Festival in Flagstaff, Arizona.
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Episode Transcript:
Looking Up is transcribed using a combination of AI speech recognition and human editors. It may contain errors. Please check the corresponding audio before quoting in print.
Dean Regas: Back in February, I attended my first I Heart Pluto Fest. This is an annual multi-day celebration in Flagstaff, Arizona, about the little world far from the sun.
[I Heart Pluto Fest 2025 Audio]: Good evening, Flagstaff. We are here today, to celebrate our very favorite planet.
Dean Regas: So Pluto was discovered February 18th, 1930 by Clyde Tombaugh at Flagstaff's Lowell Observatory, and well, they are very serious about Pluto in Arizona.
[I Heart Pluto Fest 2025 Audio]: It's Flagstaff's planet. It's Arizona's planet, and it's the United States' planet world, and it's the world's planet. Absolutely. There we go. In that order.
Dean Regas: The special guests for the Fest included Astronomy Magazine editor David Eicher, astronomer David Levy and Adam Nemoy, the son of the actor, Leonard Nemoy, who played Mr. Spock on TV's original Star Trek.
But the man with the most Pluto experience on the stage was definitely Alan Stern. He is the guy I really wanted to talk to. From the studios of Cincinnati Public Radio, I'm your host, Dean Regas, and this is Looking Up, the show that takes you deep into the cosmos or just to the telescope in your backyard to learn more about what makes this amazing universe of ours so great.
My guest today is Alan Stern, the prime mover for the New Horizons mission that explored Pluto and who has since become an explorer himself.
[I Heart Pluto Fest 2025 Audio]: We'll celebrate the 95th anniversary of the discovery of Pluto with five days of exploration education in awe of the cosmos!
Dean Regas: Well, the I Heart Pluto Fest kicks off day one with a pub crawl. Oh man. Yeah, so far so good. I like this. Flagstaff breweries even crafted Pluto themed beers.
[I Heart Pluto Fest 2025 Audio]: Let's celebrate Pluto!
Dean Regas: Then there's day two. This was the reception and panel presentation by David Levy, Adam Nemoy and Alan Stern, and this took place in the historic Orpheum Theater, the exact building where Clyde Tombaugh, remember him, the discoverer of Pluto? He went to see a movie there after discovering Pluto. February 18th, 1930.
[I Heart Pluto Fest 2025 Audio]: 95 years ago this week, there's a 24-year-old, Kansas Farm Boy that had been working here in Flagstaff for about a year, and he had discovered a planet earlier that day, and he was sitting in this room that night. He had just discovered a planet and you gotta wonder what was going through his mind. He's just discovered a Planet!
Dean Regas: Day three had a huge open house party up the hill at the low observatory with lots of activities in daytime and nighttime viewing through the telescopes.
And finally, day four had a series of speakers talking about Pluto. I was one of their guest speakers, and my topic was How to teach Grownups about Pluto. Yes, it was based on my book for kids, to explain why adults are still so mad about Pluto not being a planet.
[I Heart Pluto Fest 2025 Audio]: Pluto's status was changed to a dwarf planet in 2006 (audience boos)…
Dean Regas: Oh, it was a little tense. I never said the words, “Pluto is not a planet.” I would never ever do that in Flagstaff. At the Lowell Observatory.
The crowd inferred that's what I was trying to say and I was booed, but only once or twice. But luckily, and perhaps this was done on purpose, my guest today was not in attendance. Because Pluto is serious, serious business to Alan Stern.
Alan Stern: My name's Alan Stern. I'm a planetary scientist and an aerospace executive.
Dean Regas: So I know, learning more and more about the New Horizon's mission to Pluto, I mean, just the amount of time it took to convince people to fund it, design it, launch it, then wait nine and a half years for it to fly through space to reach Pluto. You must have a unique internal drive and patience like nobody else, right? Alan?
Alan Stern: Well, first of all, you know, space flight's a team sport Dean, the New Horizons project, I'm the leader, but 2,500 men and women worked on it.
And that whole team had an amazing degree of not just competence and drive, but real stick-to-it even under some adverse circumstances in the early years. All those people wanted to go and do something larger than life, create some new knowledge, but explore farther than it ever been before.
And, when a bunch of people get together with a common purpose like that, it really can result in amazing things. And I think New Horizons is one of them.
Dean Regas: And so, what did it take for the mission to go from concept to reality? Because I know there was like a couple iterations that go back a long time until finally it gets there.
Alan Stern: Well, it took 28 years. You know, it started with a handful of scientists who were then at the start of their careers who wanted to see this region of the solar system explored.
And then 17 years later, we found out how to get the funding and then we had a competition, and our team won. So, we built a spacecraft, got it onto the launch vehicle, and launched in 2006. Then fly it across the solar system. And for those nine and a half years, we did a lot more than wait
[I Heart Pluto Fest 2025 Audio]: The 10th anniversary of the New Horizons fly-by of Pluto (audience cheers)…
Dean Regas: Yeah. Well, and so then after nine and a half years of flight the day of the flyby comes and so NASA was having a live feed with you, and I was watching, listening along. I mean, it's exciting, tense, you know, and then ultimately joyous. What was the flyby day like for you?
Alan Stern: Yeah. Well first it was one day in the middle of a hundred day fly by sequence, but obviously that day meant the most because we not only went closest but collected, the vast majority of the high resolution data sets.
The thing about New Horizons and a lot of missions now is that we don't send two, we only send one. And there's no going back. You can't make a U-turn and come back to Pluto. And so everything's gotta go right. And that means there are a lot of ways you could fail and you hope that you've thought everything out and that your spacecraft is gonna do exactly as it's commanded to do, and that there are not any surprises or if there are surprises that the onboard fault protection software can recover from that.
In our case, we'd done a bunch of rehearsals on the ground, a bunch of spacecraft rehearsals on the way to Pluto, and it all worked out just great. And it really was a textbook fly-by.
And then probably the cherry on top was that Pluto performed because it turned out to be one of the stars of the solar system. Just tremendous scientific results and a lot of character for a small body.
Dean Regas: So, what were the highlights for you of the mission? What did New Horizons reveal about Pluto that maybe surprised you or excited you the most?
Alan Stern: Well, at a very top level, smaller bodies in the solar system tend to run out of energy for their geology to run, and the moon is a good example. Our moon mostly died about a billion years after formation because it cooled off and Pluto's even smaller, and yet it's active today on a vast scale.
We found terrains on Pluto that we created yesterday, geologically, and when I say terrains, I mean terrain's the size of the state of Texas and the state of Oklahoma combined. So, Pluto's turning out all this new geology all the time, and it's got evidence of giant ice volcanoes and other things on its surface that very well.
Proof that our rule of thumb and all of our textbooks were wrong, that little planets can be just as active today as big planets. And, that’s really advanced the field a lot because it caused people to do a lot of thinking about how you can have the physics and chemistry going 4 billion years after formation. An object is at the other end of the solar system and whose surface temperature is near absolute zero.
[I Heart Pluto Fest 2025 Audio]: Alan Stern and Will Grundy and their Legion team sent New Horizons up. It flew by in 2015 and oh my gosh, Pluto is no longer a dot. It's a world.
Dean Regas: There's a picture, you probably know it well, taken by New Horizons of Pluto from this kind of like low angle where you can see the cryo-volcanoes and then the atmosphere. I mean, here you have this tiny world with an atmosphere. You know? When you saw the confirmation of that, what was that like?
Alan Stern: Well, I'll tell you what came to mind. I can remember it very well. I thought to myself, the solar systems saved the best for last.
Dean Regas: You've been involved with so many other missions. It's just so many to list off here. What are some of your favorite non-Pluto missions and maybe even some that are coming up?
Alan Stern: Well, you know, I've been involved in 30 space Missions now, and I really love the ones that I'm involved with now, which includes New Horizons and the Europa Clipper mission to study the ocean beneath Europa, Jupiter's large moon.
The Lucy Mission, that's gonna be first to study the Trojan Asteroids We launched in 2021 and are on our way to the Trojans in 2027. But I also like a lot of the missions that I've been involved in, space shuttle missions and suborbital sounding rocket missions, being a part of Rosetta as a PI on that, principal investigator, for one of the US instruments on this first mission to orbit a comet back about a decade ago.
But I have to count among my favorites, Virgin Galactic Mission 05, which I flew into space on a suborbital research mission in 2023, and I'm looking forward to flying again on Virgin Galactic on a second research mission next year in 2026.
Dean Regas: Well, I'm glad you mentioned that. So you are not only a planetary scientist, but you're an astronaut! And so yeah, take me to that moment where you decided, hey, you know, “I think it's my turn to go to space.”
Alan Stern: I think the moment when I decided I should go to space, I think I was seven or eight years old and just swept off my feet from watching things on TV and realizing this is so much larger than life, I gotta do this. This is fantastic. And it took a long time, but with the rise of commercial space flight, NASA actually selected me to fly in space with their experiment on a commercial launch vehicle. And in preparation for that, my firm, the Southwest Research Institute, had the foresight to put in place a suborbital research program, which sent me on that flight in 2023 to practice for and reduce risk for the NASA mission that I'll be flying next year.
And I'll tell you, I was very busy as you might imagine these suborbital flights are, in the case of Virgin. It's about an hour launch to landing. Your time in space is very limited. Just like Alan Shepherd who flew in space way back in 1961, your time is very compressed. You just have minutes. For the portion of the flight that's up at a high altitude, and I had nine separate objectives and a substantial checklist to get through in order to accomplish the mission's goal. So, I was really busy.
I got very little time to look out the window, but when I did, it was jaw dropping. For the first time. I could see the earth not as a little postage stamp view from an airplane but really like half of North America just out the window, right out to the Pacific Ocean. See that curvature of the earth and the thinness of the atmosphere, it was pretty awe inspiring.
I didn't have a lot of time to just plaster my face against the window, but I got a few glimpses and I found space flight addictive, and I can't wait to go back.
Dean Regas: Well, and then we’ve got lots of missions coming up that you're involved in. We've got Europa Clipper, and the Lucy Mission. They're in route and already bringing back lots of data from the Lucy Mission. What are you looking forward to most, let's say with Europa Clipper?
Alan Stern: Well, you know, Clipper's a very special mission. First, it's what NASA calls a flagship. It's a really big scale mission with a science team of hundreds of people, 13 different kinds of investigations on board to look at every aspect of this ocean mortal.
But unlike the earth, Europa doesn't wear its ocean on the outside. It wears its ocean beneath a crust of ice and rock. Could it be habitable ocean? Might it even be an inhabited ocean?
Europa Clipper’s a mission designed to find out a couple of things. One, what's really the nature of that ocean, and could it be inhabitable? Second, how hard would it be and what would it take to go and actually get a probe beneath the surface of Europa in the future down into the ocean, where we can take a look around with something like a submersible that would be landed on Europa and then make its way beneath the crust.
Maybe through fishers or through the sites of these geysers that are thought to exist on the surface or maybe some other way to get down there with cameras and more sophisticated instruments. So, we can actually look for biology.
Europa Clipper is the warmup to that, and I think it's gonna open our eyes scientifically to this whole new class of ocean worlds that we see around the solar system because it's not just Europa, it's also tight. It's Enceladus and it's probably Triton, and we think it's Pluto and quite a number of others.
These worlds where their oceans on the inside are turning out to be really common. Even in the outer solar system where the sun can barely warm the surface of their host worlds, the oceans we know are made of liquid water, so they're warm enough on the inside to have liquid water. And those might be very conducive environments to biology all across the solar system. And we're gonna find out.
Dean Regas: Well, this is awesome Alan, thanks so much for taking the time to talk with me today about all these missions and you will come back and talk again after your next space mission. Right?
Alan Stern: Be happy to Dean, thanks for asking me on today.
Dean Regas: So, let's get back to the I Heart Pluto Fest.
And it was there that one of the guests, astronomer David Levy, tried several times, I mean several times to provoke an argument between me and Alan Stern over Pluto's planethood. And knowing Alan very well, I always deferred with a, “Oh, what's the point? I can't debate Alan. He would always win!” And Alan always gave me a look as if to say, ‘Darn right.’
But, all the Pluto being a planet in Arizona talk that I heard and all the tales of its discover astronomer, Clyde Tombaugh, who like almost has mythical qualities within the state, it made me think something. There's that other dwarf planet named Eris that I think has every bit of a right to be considered a planet as much as Pluto.
I mean, Eris is almost the exact size as Pluto. It has a weird orbit, has a moon, and was discovered right here in the United States by American astronomer and friend of the program, Mike Brown. So when should we expect to have a similar show in California at the Palomar Observatory? The location Eris was discovered.
When should we honor Mike Brown in a similar fashion? When will Eris Fest begin? I mean, Eris was discovered by Mike Brown on January 5th, 2005. So January 5th seems like good time to go to Palomar. Let's have Eris Fest, California. Mike Brown, Palomar Observatory. The Eris Ball is in your court. Let's make Eris the state planet of California. Let's plan Eris Fest 2026.
[Mike Brown]: Now. This is Mike Brown, discoverer of Eris. I want to invite you to celebrate this little world, which is the most massive dwarf planet known in the entire universe with me at Eris Fest 2026. If you like Pluto there, trust me, you'll love Eris. Oh, and there's free admission for all Arizonians.
Dean Regas: Looking up with Dean Regas is a production of Cincinnati Public Radio. Kevin Reynolds and I created the podcast in 2017. Ella Rowen produces and edits our show and would pay good money to see Alan Stern dismantle my Pluto arguments on stage. I don't know how much money. Hmm.
Jenell Walton is our vice president of content, and Ronny Salerno is our digital platforms manager. Our theme song is Possible Light by Ziv Moran. Our social media coordinator is Hannah McFarland, and our cover art is by Nicole Tiffany. I'm Dean Regas, keep looking up!
