Chasing New Horizons

by Alan Stern

  New Horizons had passed its “better than Hubble” imaging threshold back in April, and as a result, the LORRI camera was now starting to discern never-before-seen features on Pluto, and the science team was already beginning to discover new things about Pluto, even from tens of millions of miles away.

  For example, it had been known from Hubble imaging that one hemisphere of Pluto—the one they had targeted to fly over at closest range—had a vast, bright, reflective area splashed across it. Spectra from Earth-based telescopes had revealed this place to be rich in nitrogen and carbon monoxide ices.

  And as LORRI images of Pluto began to transform the planet from a dot in the distance into a disk with distinct, broad-scale markings, a continent-size trapezoidal feature appeared on this bright hemisphere. Because of its shape, Alan nicknamed the feature “India.” Interpreting these early images was a bit like an inkblot test. Images of the “far side” of Pluto—the hemisphere that would not be seen at closest approach—revealed four very nearly equal-size and equally spaced dark regions across Pluto’s equator that were nicknamed the “brass knuckles.” Pluto, a point of light since Clyde Tombaugh discovered it 85 years before, was now, finally, becoming a real place, before our very eyes.

  ENTER THE PRESS

  During the final weeks as New Horizons swept down on Pluto, there began a tidal wave of requests for press interviews. Literally hundreds of press outlets, from magazines to newspapers to TV documentaries to television networks, requested background stories, asking such questions as “Why are you doing this?”; “What do you expect to find?”; “How did you become involved?”; and “What’s your greatest concern?”

  There was also great interest in the finer details of the flyby mechanics, the team members’ personalities, the science of the Kuiper Belt, and much more. Nothing like this—the first exploration of a new planet—had occurred in a generation, and the media picked up on the historic nature of the events.

  Knowing that they couldn’t all get background “B-roll” footage at the flyby itself, dozens of network and documentary film companies—from across the United States, Canada, Europe, Australia, and Asia—wanted to shoot background interviews ahead of the flyby. The growing public interest was exhilarating for the New Horizons team. But the other side of that coin was that those scientists and engineers had to add multiple press interviews every day on top of all their other work. They had anticipated this would happen, but now, in the growing heat of the flyby, they found themselves taxed even more than expected. Alan:

  We were all working to get our technical job done, and our project management job, and our science job, and worrying about the spacecraft engineering, communications planning, navigation, and several hundred emails per day. But then, all of a sudden, there’s a whole other layer to the workload: every day there were several hours of interviews, often stretching into the night. And groups of school kids were coming in, too; as were local officials, national politicians, science glitterati, and even a few celebrities; and all the while APL was holding dinners and staging events for their staff and the public. We were all working seventeen- and eighteen-hour days by then, every day.

  After a couple of weeks of this, I realized, “This is the new normal; I am simply not going to get more than four or five hours of sleep on any night until after the flyby. And many nights it’s going to be less.” But rather than resent the lack of sleep, I decided to feed on it for energy—to be carried by the momentum of the flyby across six sleepless weeks, powered only by adrenaline.

  HAZARD WATCH—CLEARING THE PATH

  In the midst of all this hubbub of public and press attention, a deadly serious activity was playing out on the spacecraft and back at APL: the “hazard watch” imaging campaign, to determine if the planned path through the Pluto system would be safe for the spacecraft to fly, or if instead they would need to divert at the last minute to a safer but less scientifically rewarding path through Pluto’s thicket of moons.

  For the next seven weeks, through late June, a series of four intensive hazard searches took place. Each consisted of the same steps: the New Horizons LORRI camera blanketed the space around Pluto with sensitive images designed to detect tiny satellites and incredibly faint rings that still could pose a hazard to flight. These imaging campaigns were followed by days of data transmission to get those images to Earth, which were in turn followed by days of careful scrutiny by a team of fifteen data analyzers using sophisticated image-analysis software packages to tease out even the faintest details from the hazard watch images. Finally, once the images had been analyzed, models were run and their results were presented to Alan and Glen giving the resultant probabilities of “loss of mission.”

  Right off the bat in early May during the first hazard-watch imaging campaign, expert satellite hunter Mark Showalter thought that his software had found a new moon—in the very first set of “better than Hubble” hazard-search images. Alan thought, “Oh, here we go. As soon as we looked, we found the first one. How many are there going to be?” But fortunately, upon more careful analysis, Showalter’s “moon” turned out to be an artifact of the computer processing. That scare got everyone’s attention and provided a sobering focus on the coming weeks of hazard searches. John Spencer:

  Our first big decision point about whether to stay the course or divert was at thirty-three days out from Pluto, because the least fuel-costly engine-burn trajectory deflection to a safer course could have been made about then. Then we had other decision points at twenty days out, and then a similar cycle a couple more times in the last weeks of approach. Our last deflection opportunity was fourteen days out from Pluto.

  The verdict at each decision point: all clear; stay on target. No new moons, or rings, or other hazards were found. Once it became too late to burn the engines if hazards were found, they could still choose the “antenna-to-ram” pointing option, which would use the high-gain dish antenna aboard to shield New Horizons from impacts. John:

  We got our last set of hazard observations about thirteen days out. But still, no hazards were found. So at about eleven days out, we made the decision that there was nothing that warranted uploading the antenna-to-ram sequence instead of the nominal sequence. It was at that point that we felt we had really done our job. That’s when we went out and celebrated.

  To the best knowledge that New Horizons could provide, the path was clear! Of course the spacecraft was still at risk of being disabled by hazards that couldn’t be detected, but months before, Alan and Glen had gotten an agreement with NASA that if there was no known hazard, New Horizons would stay the course and proceed on its planned pathway through the Pluto system.

  As had the Voyagers, and as had every pioneer from the first humans who left Africa to populate the rest of the world, to the Vikings, to the Polynesians, to the Spanish and the Portuguese, to Amundsen and Shackleton, to Hillary and Norgay, to Yeager, Gagarin, Shepard, Glenn, Armstrong, and Aldrin: they were flying into the unknown in the service of exploration. Despite all their preparations, hazard searches, calculations, and computer models, New Horizons could not explore Pluto without some risk.

  As June ended and July dawned, the mission was about to make headlines and history, but exactly which headlines and what history couldn’t be known until the last hours of July 14, when New Horizons would or would not check back in after flying through the Pluto system and making its exit, hopefully safely.

  A CERTAIN TREPIDATION

  As we recounted earlier in this book, more than 2,500 Americans had worked to design, build, launch, and fly New Horizons. As July of 2015 began, emails and phone calls from those engineers, technicians, launch crew, and others were pouring in to the flyby team as Pluto approached, urging the flight team on, saying over and over again: “You did it! We did it! We’re finally there, go get ’em!”

  For Alan, Alice, Glen, Fran, Leslie, John, Jeff, Bill, Marc, Chris, and so many others, the Pluto flyby had been a major organizing principle of their lives—some, for half
or more of their careers. Now, each day, in images beamed to Earth from the Kuiper Belt, Pluto was growing in size. And it would continue to grow, day by day, until, in almost no time at all, it would be in their rearview mirror, and then, it would recede.

  What would life be like after the flyby…? One evening about two weeks out from the flyby, Alan went for a walk around the lake by his hotel with Amy Teitel, a historian and journalist, and one of the “media embeds” he had hired to help translate flyby science into NASA press releases. As they circled the lake, their discussion turned to his state of mind. Alan:

  Amy caught me off guard a little. She said something like “In a few days, the biggest thing in your career is going to happen, and then it’s going to be over. Nothing you do later will possibly equal it. Can you cope with that?” And then she said, “A lot of people might face a nervous breakdown once something like that is behind them. How will you handle it?”

  Many scientists and engineers on NASA flight projects experience some version of what Amy was talking about: they focus their efforts so intensely to achieve mission success, bonding with their team in doing something larger than life, that then, as the pivotal moments approach—the launch, reaching the target, the landing—they begin to feel a dread within. They foresee the energy and common purpose of the project evaporating; they see their team dissipating; they dread the loss of a long-sought, difficult goal no longer being in their future. In a way it’s like graduation day, when you know your life as it has been, with all its purpose and social fabric, is soon to be ending for an uncertain plunge into a new future.

  Others working on New Horizons were feeling it too. A few weeks before the flyby, Alice Bowman came to Alan and said that some on her mission operations team were dreading the flyby that they had worked so many years to plan. They wished they could put the brakes on it, she said, and savor this time and place a little more. Some, she said, didn’t quite know what they would do when the beacon of exploring the farthest planet ever attempted was in their past, rather than their future. Alan:

  When Alice told me that, I realized that for so many years exploring Pluto had been a bright shining light, beckoning all of us onward to the future and I thought, “God, we’re all feeling the same thing.”

  I told Alice to tell her folks to look forward to having actually accomplished the exploration of Pluto, something almost no one thought our team could pull off when we started. I told her to tell them that they could revel in the images and other data, and all we were about to learn about this entirely new world. And I told her to savor every day left from here to Pluto, because none of us would probably experience anything quite like this ever again.

  14

  JULY 4TH FIREWORKS

  CORE LOAD COLLAPSE

  The weekend of the Fourth of July holiday gave many on the New Horizons team a brief but much-needed break and a last chance to recharge their batteries before the upcoming flyby, then just ten days away. Mission operations remained on duty to fly the spacecraft, but most others took time off to fire up grills and relax. It was reminiscent of the Christmas break the launch crews had taken in late 2005, which helped morale leading into the nonstop intensity of the launch campaign that following January.

  Long before dawn on the morning of the Fourth, flight controllers in the MOC were to radio the Core load up to the spacecraft. This was the long command script that New Horizons would follow to execute its many hundreds of scientific observations during the nine days surrounding closest approach and flyby. Aptly named, this exhaustively tested command script would literally perform the core of the mission, and its faithful transmission and execution would direct New Horizons through every twist and turn, every computer memory assignment, every communication with Earth, every camera shot, and so forth.

  The uplink was Alice Bowman’s show, and Alan wanted to witness it. He considered seeing the Core sequence launched by radio commands to New Horizons akin to seeing the spacecraft launch firsthand. So, following his habit of wanting to be in mission control during the most crucial moments, Alan arrived at the MOC at APL at about three thirty in the morning to watch the flight controllers send the Core load. No one was there except for Alan and the two-person flight-control team. He brought them doughnuts, a familiar good-luck tradition.

  After arriving, he sat in the back of the darkened MOC for about an hour and a half just watching and making occasional small talk while the flight controllers sent the command load from Earth out toward New Horizons in the Kuiper Belt. He thought a lot about all the years it had taken to make this happen, how much was riding on the successful operation of this single command load, and how much new knowledge this load would create. As he watched, he felt proud of the New Horizons team for a decade-long flight mission done so well.

  By 5:00 A.M. the entire flyby command script was on its way to Pluto, ripping across 3 billion miles of yawning vacuum at the speed of light. Satisfied that all was well, Alan went to his APL office to get some work done. With almost everyone gone for the Independence Day holiday, it was a chance to get caught up on the growing torrent of email, meet with the public-affairs and encounter-logistics teams, and do a couple of phone interviews with the press before the onslaught of the next week began.

  Among the emails waiting in his in-box were two messages from Alice Bowman that had come overnight. The first read, “Please don’t go to the Mission Operations Center during the command upload. If the PI is there, it’ll distract the flight controllers during this critical operation.” Her second message read, “I know you want to be there at this special time, but this is one of my superstitions. I just feel like we should let them work this alone. Even if you’re just somewhere in the back of the MOC, I’m worried it’ll be bad luck.” Alan regretted not having seen these emails earlier but it was too late now, and besides, everything had gone fine in the MOC.

  As the morning passed, Alan thought more than once about the flyby command load winging its way across the solar system to New Horizons:

  I kept watching the clock, thinking it’s been an hour now—the load has crossed the orbit of Saturn; it’s been two hours now—the load has crossed the orbit of Uranus. By mid-morning, the load had reached the spacecraft out near Pluto, covering in just four and a half hours the distance New Horizons had taken nine and a half years to traverse. In another four and a half hours, I thought, we’ll get the signal back that confirms the load has been received and properly loaded into memory. I went back to work.

  LOSS OF SIGNAL

  Early that afternoon, Alice Bowman was in the MOC with a handful of other mission operations personnel, waiting to see the report come back from New Horizons indicating it had received and stored the Core load. At about 1:00 P.M., and right on time, the first signals started coming back confirming the reception of the command script. Alice:

  Everything was going fine until we hit about 1:55 in the afternoon. Suddenly, we lost all communication with the spacecraft. Dead silence. Nothing. We’d lost comm. And it didn’t come back.

  Nine times out of ten, when we lose signal, it’s a problem with the ground station: something’s out of configuration, or whatever. Because this upload was so important, we had our network operations engineers online. We call them NOPEs: that’s their acronym. We also had our Pluto Aces—which are the controllers there in our ops center. So we had the Pluto Aces ask the NOPEs at the ground station in Australia to check their system configuration. All those checks came back that everything was nominal with the ground system.

  That meant that the problem was not down here on Earth—not in Maryland where Alice and her team of Pluto Aces were gathered, nor in Australia where the NOPEs were at the Canberra station of the Deep Space Network receiving the signal from New Horizons. The loss of signal was due to a problem with the spacecraft itself.

  Loss of communications is about as bad a thing as a mission control team can experience—it means the link to Earth is broken. But that’s not the worst of it. It could mean
the spacecraft had suffered a catastrophic failure. Alice felt a ripple of unfamiliar fear:

  You know that feeling in the pit of your stomach when something is occurring, and you can’t believe it’s happening? We’d come nine and a half years on this journey, and I couldn’t believe this—we’d never lost communications. You allow yourself that five, ten seconds of feeling that fear and disbelief, but then everything we trained for started to kick in.

  The sudden loss of signal fed the worst fears that something catastrophic might have happened to the spacecraft. New Horizons was still millions of miles from Pluto, and any hazards it posed. The chances of striking anything there in interplanetary space were absurdly low. But, nonetheless, everyone on the team had the passing nightmare thought: Could we have just hit something? Glen Fountain recalls:

  I was home when Alice Bowman called me and said, “We just lost contact.” I only live about ten minutes away from work, and I made it back to the Laboratory in record time. Driving back into the Lab, all kinds of things go through your mind. I called Alan, and he was at APL, so he actually beat me to the MOC.

  When Alan got the call from Glen it was surreal. He couldn’t believe he was actually hearing Glen Fountain telling him, his voice laden with gravitas, “We have lost contact with the spacecraft.” It was a frighteningly serious problem. Alan:

  For a second I thought, “Alice’s premonition about my being in the MOC this morning when we radiated up the Core load is coming true.” Of course, that’s completely illogical, but I did have that fleeting thought.

  But I put that out of my head. I was out of my office and into my car within ninety seconds, driving the half mile or so over to the building where the MOC is. On the way I called NASA Headquarters to give them a heads-up. I parked and ran through building security and into the MOC.

  Because the team had telemetry from the spacecraft before it went silent, Chris Hersman and his engineers, already arriving as well, had some clues to work with. Something key they discovered very quickly was that just before the spacecraft’s signal stopped, the main computer had been doing two things at once, both of which were computationally demanding. One of these tasks was compressing sixty-three Pluto images taken previously, in order to free up memory space for the close flyby imaging soon to begin. At the same time, the computer was also receiving the Core load from Earth and storing it in its memory. Could the computer have become overloaded by this intense combination of computational tasks, and as a result rebooted?