Chasing New Horizons

by Alan Stern

  Feeling fed up with the impossible request to fly a Pluto mission for under $400 million, and excited by the idea of getting a free launch, Alan therefore decided to change the game. With Staehle’s knowledge, but otherwise more or less on his own, Alan decided to reach out to Russian counterparts to explore the possibility of getting them involved. Without anyone’s permission, he flew to Moscow and went to see Alec Galeev, the head of the prestigious and pioneering Space Research Institute in Moscow, the Russian equivalent of JPL. Alan:

  I’d never met the man, but I knew he was very powerful and he was our hope for getting a Pluto mission done within Goldin’s cost box. So, I pitched him, saying something like, “Your country has never been able to do the outer planets. We’ll make you part of our very highly visible Pluto mission, the Everest of planetary exploration. What we want from you is a contribution of the launch vehicles. It will help resurrect your planetary program, and we’ll put Russian engineers on the project. We’ll teach you everything about outer planets exploration, and you will get the credit and pride of launching the first mission to the last planet.”

  Huntress got wind of this plan from JPL just before Alan left on the trip and tried to stop him. Literally, when he was at the airport leaving. Alan:

  I got a phone call saying, “Don’t get on the airplane! No one’s given you permission to go talk to the Russians!”

  Wes:

  I think what Alan did was irritate some of the folks in the international office at NASA Headquarters that we had this rogue scientist going over there to talk to our main contact for planetary cooperation. What’s this guy doing? He’s not part of our protocol. It kind of ticked them off. I just had a cup of coffee and kind of giggled.

  But Alan knew there was no way to meet Goldin’s price target without free launchers, and playing by the rules had been getting them nowhere. Alan recalls:

  So, I got on the airplane, I went over there, I pitched it, but Galeev and his folks told me, “Nyet.” He said there wasn’t enough in it for them and they didn’t want to just be used for the launch on day one, with everything else in the mission being American. I remember it was January 1994, and it was blizzarding hard outside in Moscow. Just horrible weather. It felt as cold as Pluto.

  But I went back the next day and Galeev said, “We have a new proposal. Your American spacecraft could also carry a Russian probe that would separate and enter Pluto’s atmosphere with a mass spectrometer just before it would crash-land on Pluto.” This way the Russians would have a really unique part of the exploration at Pluto, and they could boast that they, not we, had actually touched Pluto. Galeev said, “If we can do that, I can get you the Proton launchers.” I told him I thought I could sell this back home, so we adjourned to a banquet over vodkas and Georgian red wines.

  The Russian atmospheric-probe idea made the trip a success. I was so excited that I didn’t even fly home to Colorado; I went directly to JPL, sat down with Staehle and Weinstein and their whole team. I explained, “This is how we can make it work: it’s the end of the Cold War. It’s the Russians and the Americans doing the last planet together.” They liked the concept too, and they also felt it was a victory, as a way to get in Goldin’s impossible cost box.

  Alan next took the idea to Huntress at NASA Headquarters. Though he was annoyed at Alan’s rogue diplomacy, Huntress was actually enthusiastic about the idea of working with the Russians on this. So Huntress sold the idea to Goldin and organized a NASA trip to the Russian Academy of Sciences to explore the joint mission concept further. With Alan and other Pluto scientists in attendance in Moscow a few months later, Huntress pitched the Pluto mission as “The first outer planet mission for Russia, and to the Siberia of the solar system as well!” It was a long shot that introduced a whole new set of unpredictable variables involving international relations and diplomacy into the already complex game of getting a Pluto mission funded and approved. Yet Huntress felt it was worth a try.

  But no sooner did Huntress come aboard than the Russians decided they would not provide a launch vehicle for free. The price they instead demanded was substantially cheaper than using an American rocket, but not zero.

  At that time, U.S. government agencies like NASA were, by law, not allowed to purchase Russian rockets. So the Americans needed to involve a third country to pay for the Russian Proton rockets. Alan started asking around and learned that the German space agency might be interested, if their scientists could add their own probe to be dropped off during the planned Jupiter gravity assist flyby, to study Jupiter’s moon, Io.

  But it got even more complicated on the American side. There was a new concern within NASA against launching the mission’s must-have nuclear power source on a Russian launch vehicle. Many felt that this would never be approved by other U.S. agencies that had signature authority on nuclear-powered spacecraft—like the Departments of Defense and Energy and the EPA.

  It all became a bridge too far. The Russian launcher gambit that had looked so promising soon disintegrated. Now, 1996, they were back to square one.

  A DREAM DEFERRED

  For the Plutophiles, the late 1990s was a low point in morale. They had been at it for over half a dozen years, week in and week out. They had felt so close to their dream in 1991–1992, only to see it devolve into a maze of frustrations in the years since. Having once seemed likely to be fast-tracked at the beginning of Dan Goldin’s tenure, a mission to Pluto was no longer the shiny new thing; it had become battered and worn.

  In fact, now there was another new darling of the outer solar system: Jupiter’s moon Europa, which had been revealed by the Galileo Jupiter orbiter to likely have an ocean inside it—something then unprecedented off Earth. Many in the planetary community saw Goldin’s interest in that and started to feel that their new highest priority should be to send an orbiter to Europa, following the trail of possible life in that vast ocean.

  The Pluto supporters were frustrated. Every time Alan’s OPSWG and Staehle’s Pluto team fit the mission in Goldin’s box, the rules would change. Several times they got through the SSES and through Huntress, who by then headed all of space science, only to learn that Administrator Goldin wanted to give them yet another new and frustrating assignment. Alan:

  It took me years to figure out the pattern, because Goldin always told us we were one of his favorites, and he always funded about a $30-million-a-year budget line item to do Pluto technology development and mission design studies. But he never let us actually get to the head of the line and get a new start to build a mission. Every time we got close, he had some new reason to send us back to the showers with more studies.

  At one point Goldin even told us, “I’m all for this, but you have to figure out how to do it without nuclear power.” We were incredulous: “What? Are you kidding? How can anyone run a spacecraft so far from the Sun without nuclear power?” Maybe I was a little paranoid, but this was the point at which I started to suspect Goldin was just toying with us, that he was never going to start the mission; because there was always another reason to delay, always another reason to study some other concept. So by late 1996 I began to suspect that Goldin just kept sending us on errands, and I wasn’t alone. Errand after errand after errand, each taking six months or a year to resolve. It seemed he was never going to let us out of the study box, but we knew we couldn’t quit: because if we ever walked away he’d drop the project altogether, and there would be no hope to get a new Pluto mission started. So we decided to wait him out.

  THE RISE OF THE “3RD ZONE”

  For decades, planetary scientists suspected that Pluto might not be all alone in the solar system’s outer reaches. Indeed, even as far back as the 1930s and 1940s, searches for more bodies in Pluto’s distant region were conducted—but nothing was found. More searches took place in later decades, but again they came up empty. Nonetheless, the idea that Pluto wasn’t alone gained traction from time to time as various planetary scientists made mathematical and other arguments supporting the pos
sibility of a cohort population orbiting with Pluto.

  By the time Voyager 2 was exploring Uranus and Neptune in the late 1980s, Bill McKinnon had become a key proponent of this idea. His logic was based on his analysis of Neptune’s moon Triton, so similar in size to Pluto, and his deduction based on Triton’s orbit that Neptune had captured it from a former Pluto-like orbit around the Sun. If there had been two such bodies, McKinnon reasoned, why couldn’t there be more? Perhaps even a lot more.

  The possibility that there was a vast swarm of such objects had been earlier suggested by pioneering mid-twentieth-century planetary science giant Gerard Kuiper, who sought to explain the origin of the planets. In 1950 Kuiper had proposed that the process of accretion (the building of larger objects from smaller ones), which originally formed the Earth and other planets, should have left behind a huge number of “planetesimals,” or small building blocks of planets, out beyond the outermost of giant planets, Neptune.

  Perhaps, McKinnon reasoned, as Kuiper and others had, Pluto was not just an oddball outlier but our first glimpse of what would later come to be known as the Kuiper Belt.

  In 1991, Alan took this idea further, publishing a research paper called “On the Number of Planets in the Outer Solar System: Evidence of a Substantial Population of 1000-km Bodies,” arguing mathematically, from several kinds of forensic evidence in the outer solar system, that there should be hundreds or perhaps thousands of small planets that had been created early on, constituting a whole new “3rd zone” of the solar system, beyond Neptune.

  For over a century we had referred to the zone between Jupiter and Neptune, the realm that the Voyagers had explored, as the “outer solar system.” Alan’s 1991 paper now claimed that the giant planets region might actually be the middle zone between the inner solar system, where Earth orbits, and the “real outer solar system,” where Pluto and its vast cohort lie.

  By the time of Voyager 2’s Neptune encounter, Earthbound telescopes and detectors had improved to the point that such “Kuiper Belt Objects” (KBOs), if they were indeed there, could in principle be detected. It took a few years of searching, but the new tools of electronic imagers (CCD cameras, which are in all our cell phones today) and massive computer searches (that removed the painstaking workload Tombaugh had endured) made all the difference. Beginning in 1992, planetary scientists began to find KBOs—and thus Pluto’s cohort!

  At first it was just a handful, but then more and more were discovered. Ultimately in the 1990s, more than a thousand KBOs were found, distributed in the wide zone beyond Neptune that came to be called the Kuiper Belt. Most were small, perhaps the size of just counties, but others were much larger, and a handful even rivaled Pluto in size—the size of continents. Today, based on what has been found and the vast areas still not mapped for lack of labor and funding, there are estimated to be more than one hundred thousand objects greater than fifty miles in diameter there, and an even larger, unknown number of still smaller ones.

  Fran Bagenal recollects how these discoveries added fuel to the fire for a Pluto mission:

  Interest just exploded once we started to see the Kuiper Belt Objects. It was as if it had just been a bunch of Pluto people who were interested in this lone, fascinating object at the edge of the solar system and could make a strong case for its exploration. Then it suddenly became “This is a whole new frontier!” I remember sitting in my office at CU Boulder where we were meeting to write a document to make the case for a Pluto mission. Bill McKinnon was there, and he pointed out the window to the Rocky Mountains and said, “This is like the new lands to the west that have not been explored. We should go and explore them. What’s out there?” I realized that he was right, and it got me really fired up.

  The discovery of the Kuiper Belt provided the additional scientific motivation to raise the priority of Pluto exploration back to the top. To emphasize that their hoped-for mission was now not just about exploring Pluto, but about exploring this whole third region in the solar system, the mission to explore Pluto was renamed “Pluto Kuiper Express” (PKE).

  PKE was the fifth effort to get a Pluto mission, which had begun as Pluto 350 and had been recast and renamed again and again to adapt and try to find just the key that would unlock NASA funding. Never lacking in persistence, the Plutophiles energetically went forward to define this new JPL concept.

  To put meat on the bones of PKE, and to prepare for issuing a call for the mission’s scientific instrument proposals, Huntress formed a Science Definition Team (SDT) of Pluto and Kuiper Belt experts. The SDT was charged with defining formal goals for a Pluto mission and basic specifications for the instruments it would carry to achieve these goals. It was a very good sign.

  Forming the SDT signaled that the agency had again become serious about a Pluto mission, because NASA used SDTs to kick off formal planning to create a mission new start. Planetary scientist Jonathan Lunine, who had earlier chaired the SSES, was asked by Huntress to chair the SDT. Lunine’s team included Alan and many old members of the Pluto Underground and OPSWG, and also new faces who were experts in the science of the Kuiper Belt. Lunine’s SDT worked for almost a year to craft a tight mission rationale, a list of necessary and nice-to-have scientific instruments, and a detailed scientific case. Their report emerged to rave reviews from multiple sectors in the planetary science community.

  As a result things were looking up again. But then, in late 1998, longtime Pluto mission champion and NASA Headquarters science head Wes Huntress left NASA. (Huntress told us in 2016 that his main regret in leaving was that he had failed to secure a new start for a Pluto flyby mission.) Unfortunately, his successor as Associate Administrator for science, an astronomer named Ed Weiler, was much less committed to that goal.

  Weiler did, however, keep some funding going, and in 1999, after Lunine’s SDT issued their report, Weiler’s office put out a call for teams to compete via a proposal process for funding to actually build instruments for PKE. This also seemed promising: real money to build real instruments that would fly to Pluto. The way it was structured, there would be four sensors on PKE (cameras, a composition spectrometer, an atmospheric spectrometer, and radio science to probe the atmospheric temperature and pressure), but only two winners would be selected: one for a combined package with the first three of these sensors (“the remote sensing suite”) and one for radio science which really was a different kind of instrument that didn’t fit naturally into the other group. The proposal competition became a “shoot-out” to get aboard what looked like the one and only train leaving the station for Pluto. Winning it was do or die. Competing teams formed at various labs and universities around the country, each with a team leader which, we pointed out earlier, NASA refers to as a principal investigator (or PI).

  Alan’s team proposed one of the combined imager/spectrometer suites of instruments, and it included many of the original young guns from the Pluto Underground and OPSWG. Alan believed that his most formidable competition was a powerful team of Voyager veterans from JPL, led by a U.S. Geological Survey planetary geologist named Larry Soderblom, one of the most respected names in all of planetary science—then a god of the field. How could Alan and his relatively young team possibly compete with Soderblom’s team’s experience? Well, for one thing, Alan recruited his own god, in the form of Eugene Shoemaker. Shoemaker was regarded as the founder of the field of planetary geology and had worked on virtually every planetary mission. Shoemaker was probably—no exaggeration—the most widely respected and well-liked person in the field. Nobody had more gravitas. Alan:

  I felt like Larry had the “in.” He had the better connections at NASA Headquarters, he had JPL’s A-team of engineers, and he had a really phenomenal science team. I had a great science team, too, but I always felt that we were largely a group of young insurgents, compared to the master: a guy that has been on Voyager and many other projects, and it felt like they were the incumbents—like it was theirs to lose. The idea of bringing Gene Shoemaker on board was to counte
r that. We formed our team anticipating a NASA competition later in 1998, or in 1999. At that time Gene was sixty-nine years old, and I had to really talk him into doing something that was going to be a fifteen- or twenty-year project, but he agreed to do it. I remember him saying to me, “I thought I was too old to be aboard Cassini Saturn orbiter proposals a decade ago, but this is just too much fun to pass up!”

  Alan and his team worked tirelessly on their proposal, refining for almost eighteen months. To make it stronger, outside experts were brought in to critique every aspect of the proposal, to help improve the designs, management plans, plans for education and public outreach, schedules, and more. The other competing teams of course did the same.

  Proposals were finally due in the spring of 2000. NASA then convened a suite of expert review panels to evaluate all the proposals. Through back channels in the summer of 2000 Alan got word that his team had won for the camera/spectrometer suite. That was encouraging, but then … there was only silence. Alan:

  We kept waiting and waiting for NASA to tell us that we had won, but then out of the blue I got a phone call from Rob Staehle in late August of 2000, and he said, “It looks like Weiler has decided to cancel the whole thing.” How, when instrument selection decisions had apparently already been made and a mission new start finally seemed imminent, could this have happened? I was floored.

  THE STOP-WORK ORDER

  As it turned out, while the instrument proposals were being evaluated, NASA Headquarters discovered that engineers from JPL had created a budget monster. Weiler had been promised PKE could be done for less than $700 million. But when Weiler ordered a cost review, it was found that JPL’s real cost was going to be nearly twice that, maybe more.