To Pluto and beyond! The inside story of a mission to the edge of the solar system

Nearly three years ago, on July 14, 2015, NASA's New Horizons space probe accomplished the historic flyby of Pluto — the last of the major bodies in the solar system for our spacecraft to visit, and by far the most remote.

Quirks & Quarks host Bob McDonald recalls the thrilling moment as he was present at NASA's Mission Control as a spectator when the probe reported in. It was the end result of a quarter century of work by a team led by Dr. Alan Stern, the Principal Investigator on the Mission, and it was a triumphant success after almost an entire working lifetime of ups and downs, close calls and near disasters trying to make this encounter with Pluto possible.  

New Horizons lived up to its name. It provided stunning pictures for the public and a huge wealth of information for scientists — data they're still combing through to learn about Pluto and the distant reaches of the solar system. Dr. Stern is still involved in that work, but recently, he took the time to look back on the New Horizons' mission, and document it in a new book. It's called Chasing New Horizons: Inside the Epic First Mission to Pluto. Here's Bob McDonald's conversation with Dr. Stern:

This interview has been edited for length and clarity.

Bob McDonald: Much of your working life has been devoted to trying to get this mission to Pluto. Now we will talk about the success in just a second but you tell a fascinating story in your book about how many failures you were involved with before New Horizons even happened. Tell me about that.

Alan Stern: Well, Chasing New Horizons really is a story of persistence and pluck by a whole team, not just myself, but really 2,500 men and women worked on this project. There were a lot of rough patches getting it started. Pluto's very far away and it takes a long time to get there. We worked really from 1989 until 2003 before we secured the funding, 14 years. And during that period of time, there are more false starts than anybody can count. I used to say that if Pluto mission was a cat, it would have been dead long ago. That's when we get nine lives. There were times when we had the wrong management team and it got too expensive. There were times when the scientific community wasn't behind it. There were times when just something random would happen -— a spacecraft blew up days before reaching Mars and NASA decided to take the money away from doing the Pluto mission and replace that spacecraft. And so it really just took persistence.

BM: Well, every space mission to the planets is difficult, but this one I think more so because of the sheer distance and the remoteness of where you were going. Tell me about some of the unique challenges that were presented in trying to get to Pluto.

AS: When we were awarded the project. We had two very tall challenges. One was that because of the orbital mechanics and the way the planets were aligning, we needed to fly past Jupiter to get a gravity assist and the only opportunity to do that was in January of 2006. The problem was we were selected in late 2001, which gave us just four years and two months to design and build that spacecraft, get it tested and into the launch pad. That's less than half the normal amount of time. But on top of it, we only have about a fifth as much money as Voyager had. So you're gonna have to figure out not only how to do it twice as fast but for two dimes on the dollar. That took a lot of innovation and a lot of nights and weekends.

BM: Now another thing that you talk about in the book is trying to design something that was very small because of how far you had to go and the energy involved. Tell me about that.

AS: Yeah, we wanted to design the smallest possible spacecraft and then buy the largest rocket anybody would sell us and trick it out with every upgrade to make it go faster because the combination of a small spacecraft and a giant rocket is blazing speed. We had to severely miniaturize scientific instruments onboard. In fact, all seven cameras and spectrometers and other scientific devices onboard to take data about Pluto and its system of moons weigh less than just this camera on the Cassini Saturn orbiter. And because our power budget is so low, if you turn all seven instruments and their microprocessors on at once, it's a draw of 28 watts, about half a light bulb.

BM: You were on a very hard deadline there, you only had this opportunity to launch to take advantage of that Jupiter fly by, the gravity assist.

AS: Right. We had that single launch window of three weeks in January of 2006 and it was kind of a get it done on time or go home because Jupiter wasn't going to be back in position for a decade. And I'm sure we would have been cancelled because you can't just keep a standing army around waiting for ten years for the next launch opportunity, and we got to the launch pad and we had a flawless launch and we were off across the solar system on probably the grandest adventure I'll ever be involved in in my professional career, exploring the farthest worlds in history.

BM: Well, one of the other challenges that you had is that you needed a large team of people to design and build and launch the spacecraft, and you needed a large team of people when it arrived at Pluto to fly that thing and get all the data back. But it took nine years to get there. You had to just wait. So what was that period like?

AS: We weren't waiting. You know one of the innovations of New Horizons was the way that we revolutionized the mission operations team. On the Voyager project that went out to Jupiter, Saturn, Uranus and Neptune, their team had 450 people to operate those two spacecraft. But through advances in automation, through hibernating our spacecraft that is putting into sleep a lot of the time, we were able to do the same work with only 50 bellybuttons, 50 men and women, for flight operations, engineering science, management, public affairs, everything. And that meant the 50 of us were very busy. Alice Bowman, who's our mission operations manager, basically the czar of our mission control, called it a nine-year sprint, because there was so much work involved to fly the spacecraft and navigate the spacecraft to get the Jupiter flyby right; to plan not just the Pluto flyby but backups and malfunction procedures and train everybody, you know, we were just working around the clock, we were not waiting at all. We were working the entire nine years as that spacecraft crossed the solar system.

BM: Okay, so nine years passed. There you are, approaching Pluto, getting ready for the fly by, your one and only chance to observe Pluto up close and your spacecraft computer crashes.

AS: Well, it was worse than that. It really was because the spacecraft went offline and that's never supposed to happen. We were communicating with the spacecraft ten days before fly by. We'd had this flawless flight for 3,300 and 50 days. And here we were, right on the heels of getting the goods at Pluto. We're talking to the spacecraft, it's Saturday July the 4th. In the United States, that's a good day for fireworks, but these are not the fireworks we expected. The spacecraft literally while talking to us just went dizzy and went offline and that's never supposed to happen ever to any spacecraft. It turns out our main computer had been overloaded and the backup computer saw that it was in trouble and it shut down the main computer which is what it was supposed to do and took over control. When we re-established contact, we found out that the main computer shutdown meant that it had erased all of the flyby plans that had been carefully put up as a series of files over a period of months and we had three days literally to put all that Humpty Dumpty back together again. We immediately called everybody on our flight team together, people were coming in from the holiday, from barbecues and picnics in their flip flops and their shorts. And it did not look like a spacecraft control team. It looked like some sort of a party. But for three days, no one left. They were sleeping on desks and they were sleeping on the floor and eating out of candy machines. If you saw the movie Apollo 13, it was it was just like that —  racing against the odds not to save Jim Lovell and his crew but to save this 26-year enterprise and this one little spacecraft, which was going to Pluto whether we got the flyby plans back up on the spacecraft or not. And you know they did it with only four hours to spare. Somebody ought to make a movie.

BM: The encounter in the end was textbook perfect. There was excitement in the air, the pictures were stunning, everyone was jumping up and down. We were all really happy. What was it like for you? Were you more thrilled or just relieved that it even happened?

AS: The joy of seeing this team that had work so hard succeed and how beautiful Pluto was and how intense the public interest was is something I'll never forget. The most prized missions in NASA I think are the ones that are these first visits to a new planet. And nobody done anything like this since the 80s. And for our generation, this was the only 21st century opportunity to do that. Literally two billion people I'm told visit our website in one 48 hour period. It's just amazing.

BM: Now we've covered some of the amazing pictures and science that came out of New Horizons and you devoted an extra appendix to it in your book summarizing it. What are some of your highlights?

AS: We found in this little planet Pluto, about the size of the United States, flowing glaciers, avalanches, snowing atmosphere, volcanoes the size of Mauna Loa, five fascinating moons. There's strong evidence of a liquid water ocean that could be an abode for life inside of Pluto. I mean the scientific discoveries that were raining down were so intense and so numerous that I think my highlight was just how complicated Pluto proved that a small planet can be — as complicated as the Earth or Mars.

BM: And just a year before that we knew nothing about Pluto, it was just this little ice ball, and yet after New Horizons Pluto it was alive in a way.

AS: Well very much so. It is alive geologically and atmospherically, it's got terrains on its surface that are a million square kilometers the size of Texas and Oklahoma combined that were created yesterday geologically. And none of this was really expected because we didn't really have a good idea. I mean everything we knew before the flyby could fit on one sheet of paper more or less. Reporters asked me if we're going to rewrite the textbooks on Pluto. I'd say no, we're going to write the textbook because we don't have one yet.

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BM: Well, there's still new science coming out and just a couple of weeks ago I noticed that you were one of the authors on a paper about dunes on Pluto.

AS: Right. We just had a very important paper came out that we've discovered vast dune fields of solid methane snow dunes —  what a sci-fi planet this is — that stretch over thousands of square kilometers created by winds that you really can't have in Pluto's atmosphere today. It's probably evidence that Pluto's atmosphere was much thicker in the past, thicker even than Mars's atmosphere. So we are learning that this little planet that's complicated now was even more complicated in its past and I think we need to go back with an orbiter and really stay and explore in detail.