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New Horizons launch
An Atlas 5 carrying New Horizons lifts off from Cape Canaveral on January 19. The launch came after well over a decade of work to mount a mission to the outermost planet. (credit: NASA/KSC)

A journey’s ending and beginning

On Tuesday afternoon I stood outside at the Kennedy Space Center press site, on empty ground that until recently had been the home of a grandstand used by reporters covering launches, and waited. For the last two hours several dozen of us, ranging from reporters and photographers to KSC employees who had wandered over from nearby buildings, had been standing around in the warm sunshine and strong breeze, waiting for the launch of the New Horizons mission to Pluto. That strong breeze, which under other circumstances might have felt quite pleasant, was the reason why were waiting: the wind gusts were at the limits of what was acceptable for launching an Atlas 5. Coupled with a few other minor problems—a balky valve on the launch vehicle and momentary glitches with a downrange tracking station and the Deep Space Network—the wind had pushed the launch back from the beginning to the end of its two-hour launch window. Any more problems, weather-related or otherwise, and the launch would be scrubbed for the day.

Finally, the announcement came from launch control: they would start the countdown from its hold at T-4 minutes to permit a launch at 3:23 pm, the very end of the launch window. Winds were still borderline, so if there was a gust that exceeded the limit of 61 km/h, controllers would call a hold, scrubbing the launch for the day. Those of us who had stuck out the two hours of delays gathered outside again for one more try. As the countdown picked up at T-4 minutes, I looked over to my left and saw Richard Binzel, a member of the New Horizons science team (and a professor of mine from my grad school days at MIT) who was at the press site to answer reporters’ questions about the mission. He smiled and gave me a thumbs-up. I responded not with a thumbs-up but instead with crossed fingers: a fair amount of luck was still needed to get the spacecraft off the ground today.

For a moment—a minute and 26 seconds, to be exact—it appeared that the requisite luck would hold out. Then came the call over the loudspeakers: “Flight control, no go.” A loud groan erupted from the crowd. “Flight control, no go at T minus two minutes and 34 seconds due to a red line monitor fault.” The winds had once more gusted above acceptable limits, dooming the launch for that day. The crowds dispersed as people returned to their offices or retreated inside the press center to file dispatches about the scrub. New Horizons would have to wait another day.

Binzel smiled and gave me a thumbs-up. I responded not with a thumbs-up but instead with crossed fingers: a fair amount of luck was still needed to get the spacecraft off the ground today.

As it turned out, the mission would have to wait yet another day, until Thursday, as Wednesday’s launch was scrubbed hours before the scheduled liftoff time because of power problems at the spacecraft’s mission control center, the Applied Physics Laboratory (APL) in Maryland. Each day’s delay raised concern about missing the launch window, which closed in mid-February. If the launch was delayed after January 28, the spacecraft’s arrival would slip from mid-2015 at the rate of about one year every few days. Yet project officials, including those who had worked for many years to get a mission to Pluto, were not rattled by the delays. “I’ve been working on this for 17 years,” principal investigator Alan Stern said to reporters after Wednesday’s scrub. “Two or three days doesn’t make a hill of beans.”

A fast flyby

To the casual observer, it might seem surprising that anyone has been working on a Pluto mission for 17 years. New Horizons was formally selected by NASA just a little over four years ago, in late 2001. However, while New Horizons is the first mission to Pluto, it is not the first time NASA has made a serious effort to develop a mission to the outermost of the nine planets. For most of the 1990s there were efforts, primarily at JPL, to develop a small Pluto flyby mission, including one project where I played a cameo role.

In the fall of 1991 I was starting my junior year at Caltech. While my major was geophysics, and I was at the time considering pursuing a career in seismology (I had just finished a summer research job in Caltech’s Seismo Lab), I had a passion for space exploration. I had joined the school’s chapter of Students for the Exploration and Development of Space (SEDS) almost immediately upon arriving on campus two years earlier, and had just been elected president of the chapter.

So, when the US Postal Service issued a set of stamps in October 1991 commemorating NASA’s exploration of the solar system, I naturally bought a set. There were ten stamps in the set, one for each of the nine planets plus the Moon. Each stamp featured an artist’s depiction of that planet and a NASA spacecraft that explored it: Mariner 10 for Mercury, Pioneer 11 for Jupiter, and so on. All, that is, except for Pluto: it was depicted as a featureless gray orb, with the damning phrase “Not Yet Explored” underneath it.

While the reminder of Pluto’s unexplored status didn’t register much from me (other than a passing thought that it would, someday, be nice to send a mission there), the reaction was a little different a few kilometers up the road at JPL, where the first-day-of-issue ceremonies were held. Pluto’s status got two JPL employees who attended the event talking about what it would take to send a spacecraft to Pluto. Because Pluto was beginning to recede from the Sun in its elliptical orbit (at this time Pluto was still closer to the Sun than Neptune), it was imperative to get there as quickly as possible lest the planet’s tenuous atmosphere, discovered just a few years earlier, froze out. Getting there quickly meant making the spacecraft as small as possible—but not so small that it could not do useful science once it got there.

I warned Staehle that probably only a handful of students would attend a meeting about the mission. In fact, over 20 people, from freshmen to grad students, attended and showed a strong interest in participating in the project in some manner.

One of those JPL employees was Robert Staehle, who took the lead on studying a small Pluto flyby mission at the lab. Besides his work at JPL, Staehle was president of the World Space Foundation, a nonprofit organization headquartered in nearby South Pasadena that was planning a solar sail mission, originally as part of a race with solar sails from Europe and Asia to commemorate the 500th anniversary of Columbus’ voyage across the Atlantic. SEDS chapters in the area, including Caltech SEDS, had worked with the World Space Foundation on that project, so it was little surprise that Staehle turned to SEDS in late 1991 to see what role students could play on a Pluto mission.

This was the entrée for myself and a number of other students, primarily fellow Caltech undergrads and SEDS members, into what became known as the Pluto Fast Flyby (PFF) project. On January 28, 1992, Staehle came down to the Caltech campus to give a presentation about the mission, and to open a discussion about the role students could play on the mission. (The exact dates and other details in this and following paragraphs come from two three-ring binders of notes about the project that I kept at the time and managed to retain through the intervening years; until recently they had been alongside a copy of my PhD thesis in a box stashed away in the back of a closet.) As Caltech SEDS president, I had organized the meeting, but warned Staehle that probably only a handful of students would attend. In fact, over 20 people, from freshmen to grad students, attended and showed a strong interest in participating in the project in some manner.

After some discussion, the best role for students in this early phase of PFF was to build a full-scale mockup of the spacecraft, based on the existing, basic design. The design did not have to be highly accurate, given budget and schedule limitations as well as the overall preliminary nature of the project in general, but it had to convey the scale of the spacecraft (particularly when compared to behemoths like Voyager and Galileo) and put the major components in the right locations. According to my notes from an early meeting, the mockup had to be “suitable for fairly-close inspection” but “nothing necessarily needs to work.”

Soon, a team of nearly a dozen Caltech students was working part-time (either for pay or class credit) on the mockup. They scavenged components from various corners of campus or junkyards in the area: the high-gain antenna for the mockup was an old C-band satellite TV dish, trimmed down to the required diameter. I didn’t work on the project directly, given an absolute lack of mechanical engineering skills, but instead took on a role as project liaison, attending weekly PFF team meetings at JPL to inform them of the status of the mockup, and pass along project updates to the students working on the mockup.

The original plan called for the mockup to be complete by the beginning of June, around the end of the spring term at Caltech. However, like so many other projects, the schedule slipped, and students continued to work on the mockup into the summer. The project faced a hard deadline of late August, however: NASA had offered to include the mockup in its pavilion at the World Space Congress, scheduled for the week before Labor Day in Washington DC. The mockup had to be completed by the morning of August 21, 1992, so it could be shipped to Washington in time for the convention. This meant a last-minute flurry of activity, including an all-nighter the night of the 20th, where even I—who was working that summer at JPL on an unrelated project—pitched in. A sign I preserved from that effort, most likely written by Rich Zitola, the student who led the mockup work, had “Pluto Mission” written on the bottom and, above that, in all caps, “DEADLINE: ABSOLUTELY, POSITIVELY, NO LATER THAN 0900 FRIDAY AUGUST 21, ’92”. Scrawled to the right of that deadline: “AAAHHH AAARRGH!!”

Despite that deadline pressure, the mockup was indeed completed by 9 am on the morning of the 21st, and members of the PFF team filed into the lab to have their picture taken with the mockup: the first opportunity for many to see how big—or, rather, how small—Pluto Fast Flyby really was. After that the mockup was carefully disassembled, packed in shipping crates, and sent off to Washington for display at the World Space Congress and, later, at NASA Headquarters, before returning to JPL.

PFF team photo
Caltech students and JPL employees gather around a full-sized mockup of the Pluto Fast Flyby spacecraft in August 1992. Rich Zitola, the student who led the work on the mockup, is in the front row, kneeling, at the far left; next to him is Robert Staehle, PFF project manager. The author is in the back row, third from right. (credit: NASA/JPL)

A long road to Pluto

The mockup was not the end of student involvement in PFF. Students worked on various aspects of the project, including new mockups to reflect changes in spacecraft design. SEDS even proposed to run a student naming contest for the mission, although that proposal was deemed premature and shelved. My own personal participation, though, was coming to an end: I passed on leadership of the Caltech SEDS chapter my senior year, and graduated in 1993, moving across the country to study planetary science at MIT. My contacts at Caltech and JPL naturally faded over time.

A sign from the final stages of the mockup project had writteon on it in all caps, “DEADLINE: ABSOLUTELY, POSITIVELY, NO LATER THAN 0900 FRIDAY AUGUST 21, ’92”. Scrawled to the right of that deadline: “AAAHHH AAARRGH!!”

PFF made slow but steady progress over the years. A preliminary schedule, dated November 1992, featured the launch of two spacecraft in 1999–2000 that would fly past the planet in 2007. (PFF planned for two identical spacecraft as a contingency in case one spacecraft was lost; if both spacecraft survived the launch and journey they were designed to arrive at different phases of the planet’s six-day rotational period to ensure maximum high-resolution imagery of the surfaces of Pluto and Charon.) For a time there was serious discussion about making PFF a joint mission with Russia, with Russia providing Proton launches in exchange for the inclusion of a Russian-built impactor probe, or “drop zond”, on the flyby spacecraft. This was in the golden era (some might argue “Goldin era”, after then-NASA administrator Dan Goldin) of US-Russian space cooperation in the early-to-mid 1990s, as yet untempered by the realities of Mir and the ISS.

By the late 1990s PFF had become Pluto Express (and later still Pluto-Kuiper Express (PKE), incorporating the possibility of a flyby of a distant Kuiper Belt object) and been integrated into an overarching JPL program dubbed “Ice and Fire” that featured a Europa orbiter mission and a solar probe, all using similar hardware components. However, increasing costs and shrinking budgets doomed the mission: in September 2000 NASA announced it had issued a “stop work” order for PKE, electing to devote its limited resources on the Europa Orbiter program. (It, too, would eventually be canceled.)

The end of PFF, fortunately, did not mean the end of a Pluto mission. Facing a backlash from planetary scientists (who deemed exploration of Pluto a top priority for the coming decade) and the general public (who wanted the US to “complete” the exploration of the planets of the solar system), NASA relented and issued an announcement of opportunities (AO) for a new Pluto mission. Pluto supporters needed the help of backers in Congress to keep NASA from canceling the AO and, later, adding funding for the mission to NASA’s budget. That effort resulted in New Horizons, which is now on its way to the outer frontiers of the solar system.

New Horizons is not, strictly speaking, a direct descendant of Pluto Fast Flyby. New Horizons was built by APL, not JPL; it weighed 478 kilograms at launch, about three times the mass of PFF in its fall 1992 design; and it carries seven instruments (one of which is a dust counter built by students at the University of Colorado), compared to the four on PFF. By any account, New Horizons is a far more capable spacecraft than PFF, and able to do far more science than what PFF could have done. “The payload that we’re flying… is a much more advanced payload than we could have flown, for example, in the last Jupiter launch window ten years ago,” Stern said at a pre-launch press conference.

Given my early bit part with PFF, and the trajectory my career has taken since then, this may well be the closest I will ever be to directly participating in a planetary mission.

Nonetheless, in spirit New Horizons is closely linked to PFF. Both embody the desire by scientists and others to explore the outer reaches of the solar system, and do so in a expeditious manner, even if the scientific rationale has changed somewhat: the first Kuiper Belt object was not discovered until after PFF got started, while today, after the discovery of hundreds of KBOs, there is an open debate regarding whether Pluto itself should be considered a planet.

That long pre-history for New Horizons is also what led me to fly down to Florida to try to view the launch, when I could have covered it quite well via the web and NASA TV. Given my early bit part with PFF, and the trajectory my career has taken since then, this may well be the closest I will ever be to directly participating in a planetary mission. (And that’s not necessarily a bad thing: trust me, if I’m the one building your spacecraft, your mission is probably in deep trouble.) It made sense, if in a somewhat irrational, illogical way, to try and experience this in person.

As it turned out, the fates conspired against me: after the scrubs on Tuesday and Wednesday I had to fly back to Washington, and ended up watching the launch Thursday afternoon through a webcast at work. (Even that required a bit of luck, since I was in a meeting at the original liftoff time Thursday afternoon; low clouds delayed the launch long enough for me to escape my meeting and catch the final seconds of the countdown.) Missing out on witnessing the launch in person is frustrating, but that is outweighed by the satisfaction of seeing a mission to Pluto finally, and successfully, take off. After all, given all the years of efforts that led up to the launch, and the nine and a half years New Horizons will spend in transit to reach Pluto, what’s a delay of a day or two?