So he was content, but was that enough? Was that the same as satisfaction? Colleagues joked that Pappalardo was unhappy in front of the classroom because he took teaching too seriously. Being a good teacher was wearying work, especially at a big state school. You grade two hundred twenty papers, and they are brimming with pages of pilfered prose, and there are only so many times you can debate with undergrads the answer to a multiple-choice question before you start fantasizing about gasoline, matches, and applying both to oneself. His graduate students were great, though—curious, creative, conscientious—and he took care to advise and mentor them as Ron Greeley had advised and mentored him, to sustain that unbroken chain reaching back to Plato’s Academy. Bob relished pairing, like Gregor Mendel in his garden of pea plants, the expertise of different grad students—his potential planetary scientists—to see what might grow from the couplings.12
Bob came to Colorado by way of Brown University in Providence, Rhode Island, where he’d put in six years as a postdoctoral researcher—years longer than most for that kind of position, but he was at the time analyzing data returned from the flagship Galileo, NASA’s spacecraft at Jupiter. He was officially an “affiliate member of the solid-state imaging team,” and who would be in a hurry to leave that? Every two months, Galileo would complete an orbit of Jupiter. The relentless machine made by human hands carried cameras, sensors, and mapping tools, and every second it spent circling Jove served some purpose. When it wasn’t directing data to Earth, Galileo was studying Jupiter below or one of the two dozen natural satellites encountered along the way. (The known number of moons had grown since Bob pressed toothpicks into his painted polystyrene planets.)
Pappalardo’s job was to plan the mission’s “imaging campaigns”: what the onboard camera would take pictures of, and when, and why. That imaging campaigns were even possible was a triumph. NASA made space exploration look easy, but it never was. In Galileo’s case, scientists learned soon after launch that the spacecraft had a faulty high-gain antenna. Its collected data should have surged back to Earth, an Amazon River of zeroes and ones. Instead, it trickled home as though through a kinked garden hose. Galileo, consequently, could return only a fraction of the intended science. For members of the mission, then, it meant being methodical and selective. It wasn’t enough to know what you didn’t know; you had to know the best things no one knew, or even thought to ask, and then have the spacecraft collect the data to answer them. Observation planning was high-stakes work, made more so by the harsh reality of orbital mechanics. You miss your one shot at a particular moon, and that might be it, ever, for an entire generation of scientists. Galileo might never pass that moon in that configuration again, and it might be thirty years before NASA got another spacecraft to the Jovian system to fill the gap.
Galileo’s project and camera leads, in addition to running a spacecraft, taught and managed university departments and advised NASA and generally pushed planetary science forward. Scholars such as Greeley and his counterpart at Brown, Jim Head, or Torrence Johnson, the Galileo science lead, didn’t have time to plan which of the two blobs spotted on Europa might be more valuable to image, or how to image them, or which color filter to use, or what camera mode should be used, or what compression level should be applied thereto. But postdocs and graduate students did have that kind of time, and though Bob was relatively young, his work, and that of his fellow affiliate members of the solid-state imaging team (and the grad students thereon), were critical to mission success. It was tiring, tedious, taxing work. You had to stay on top of it. I mean, the spacecraft never stopped. The advisors consistently and unflinchingly reviewed the plans. Greeley in Arizona would sometimes ask of Bob or Louise Prockter, a graduate student at Brown, Is that picture worth a million dollars? Because this costs a million dollars per picture.13 And you had to make the argument that it was, or you had to find something better to target, and it was back to zero. And you learned to argue the science. On this flyby, do we take images of Europa, or do we point the camera instead at Gilgamesh Basin on its fellow traveler Ganymede, Jupiter’s largest moon? The Europa images would be the highest resolution ever taken. The Ganymede images would be among the worst. But those few feeble Ganymede grabs might settle some surface-age question that has long vexed scientists. Which do you choose? (They chose Ganymede.)
By the time Bob took the job in Boulder, if he wasn’t yet the world’s foremost expert on Jupiter’s moons, and Europa and Ganymede in particular, even the world’s foremost expert might think he was. He had managed, over the course of his college career and afterward, to read everything ever written about the Jovian worlds, and he possessed an unnerving ability to retain not only the literature but also the location of said literature—e.g., “I recall reading a paper on that in Nature in 1979. Turn three pages in and you’ll find a chart that might be useful.” He had a fine run of accepted papers on the geophysics of Galilean satellites and spent an awful lot of time writing reports summarizing where, exactly, scientists were in their thinking about the icy worlds. For planetary scientist Fran Bagenal’s book Jupiter: The Planets, Satellites and Magnetosphere (literally “the book on Jupiter,” as in “She wrote the . . .”), he led the Ganymede chapter and cowrote a good bit of the Europa chapter as well.
When Bob first came into the field, all the foremost experts taught—Greeley, Sagan, Head—and he had benefitted immeasurably. Who was he to do less than the founders of the field? But by 2004, it felt like all the best young scientists were moving to research institutions. How would that affect planetary science? Who would teach the basics to the next generation? Could Bob? Would he really be the best person to carry the torch if he became a burnt-out ice moon obsessive arguing with undergrads the merits of “D. All of the Above” every March during midterms?
Being pulled aside and presented with this overture from Jet Propulsion Laboratory—it was exhilarating. The lab, located in the San Gabriel Mountains of Pasadena, was an important place when it came to altitudes above the thermosphere. As an institution, it had long secured a future for the city, which was first given geography in 1771 as part of the Mission San Gabriel Arcángel’s planting of Catholic flags across the lower territories.14 (The Spanish Franciscans didn’t really count the indigenous peoples’ millennia of settlement and cultivation of the land. No, it definitely all started in 1771.) Next came colonists from the northeastern United States,15 and by 1886 Pasadena had become something of a winter outpost for well-heeled New Englanders. The Second World War made Pasadena permanent when Southern California served as a staging area for the Pacific campaign. While the army was in town, it partnered with the California Institute of Technology, whose engineers were developing an American response to an ascendant German technology called jet-assisted takeoff rockets. Thus was born Jet Propulsion Laboratory. Still managed by Caltech, it was, since 1958, more famously a NASA center, having evolved into the primary robotic research and development arm of the agency. (The buildings belonged to NASA; the employees belonged to the university.) All the multibillion-dollar large strategic science missions—the flagships—flown beyond the asteroid belt had been designed, built, and flown from there: Voyagers 1 and 2, both still coursing through uncharted regions of space; Galileo, now vaporized in the Jovian interior, its mission completed; and Cassini, only four months now in orbit around Saturn. Of course, JIMO, too, was a lab effort, and evidence that not everything its engineers touched launched.
JIMO was part of Project Prometheus, a NASA headquarters-directed initiative to use nuclear reactors to power the propulsion and payload of spacefaring vessels. The program was a personal priority of Sean O’Keefe, the administrator of NASA, and was modeled in part after the U.S. Navy’s fleet of nuclear submarines.16 (O’Keefe was a former secretary of the navy.) The idea was to send spacecraft on long-term, multiplanetary science missions in the farthest, least hospitable reaches of the deep outer solar system. JIMO would be its pathfinder, its ship of the line, its fission-fueled flagship—the fir
st of what could be an armada of similar such vessels searching the cosmos. The Prometheus reactor would change everything. Power was king in space exploration. No matter what went wrong millions of miles from Earth, the mountain people of JPL could summon an ancestral sort of strident braininess, whiten blackboards with complex equations, and send signals clear across space bearing So Crazy It Might Work instructions to get a wayward spacecraft back on track. They could heat the spacecraft by boosting power to certain components or orient it to endure direct rays from an unfiltered sun. They could shake the spacecraft, spin it wildly, extend arms and swing them round and round. They could reprogram every byte of its onboard computer. But in order to do any of this, the spacecraft absolutely needed to maintain power. If the lights went out, it was Kobayashi Maru. It didn’t even take a lot of power to keep things running. The New Horizons spacecraft set to launch to planet Pluto in 2006, a mere two years away, would travel three billion miles—to the very edge of the sun’s influence—and run rigorous analyses on the unmapped world using two lightbulbs’ worth of power: about two hundred watts.17
The Prometheus reactor, however, would produce up to two hundred thousand watts of power—a number so large that scientists had no context at all for how to use it.18 If power was king, Prometheus would be the supreme and undisputed overlord of the solar system. So with the administrator’s blessing, JPL engineers swung for the fences with JIMO. They settled on a spaceship that was as heavy as an eighteen-wheeler and longer than the Millennium Falcon. It would require three separate launches to get to space and would need to be assembled in orbit, the same way NASA was building the International Space Station. It would then fly to the Jovian system, enter orbit around one of Jupiter’s moons, look around, study this area or that, fly to another moon, orbit it, and another, and another.
JIMO was ideally suited for studying Europa because the moon resided in the heart of the Jovian radiation belt: a pulsing, rippling, four-million-mile halo of death that surrounded the largest planet in the solar system. Electrons there zipped about at just under lightspeed, and when those particles smashed into a lesser robot’s brains, zeroes got flipped to ones, and the spacecraft might have a very bad day indeed. Maybe a vital image would be wiped from existence. Maybe the computer instruction that said Absolutely do not do this suddenly read Go for it buddy—YOLO! and the billion-dollar mission would be lost forever. A starship like JIMO, though, was no mere robot. It was Optimus Prime! It was an electronic Aeneas on a celestial battlefield, radiation but a refreshing breeze tousling its hair. You want a flagship? asked JPL engineers. We’ll give you a flagship.
But first you had to get that reactor into space.
It was the size of a trash can. Something so small couldn’t cause a nuclear accident on the scale of Three Mile Island, or much damage at all, really, even if NASA put its scientists on that problem called “the Earth” and how best to make it go away. If Prometheus blew up on launch, someone might be killed from a chunk of metal hitting his or her head, but there would be no mushroom cloud, no documentaries thirty years later about where all the cows with two heads came from. But for some people, crowning a colossal missile with a uranium-powered, atom-splitting nuclear device and firing it into orbit . . . it was just a little too . . . doomsday? An awkward brush against the concept of an intercontinental ballistic missile? The thing wouldn’t switch on until it was six hundred miles from Earth, but flying fissile fuel over Florida retirees . . . it was asking a lot.
The real killer, though, was JIMO’s price tag: ten billion dollars.19 No science mission had ever cost that much. The Hubble Space Telescope cost a third of that.20 The shuttle Endeavour—the shuttle fleet then being the heart of human space exploration (NASA’s raison d’être)—cost a quarter of that.21 JIMO may as well have come in at a hundred trillion dollars. Ten billion? NASA headquarters would never keep that kind of cash flowing for a science mission. Everyone knew that JIMO would die the moment the NASA administrator retired—and all signs suggested that Sean O’Keefe, who pushed Prometheus prominently, would do just that very soon. But JPL wanted that money, so JPL needed a plan.
Enter Bob Pappalardo. It was regulation DC weather for late October that day: cool and overcast, with a light breeze.22 Over lunch at NASA headquarters, only a few minutes’ walk from the Smithsonian National Air and Space Museum, a manager from California explained to the assistant professor from Colorado that while Jet Propulsion Laboratory had the best spacecraft engineers in the world, project teams needed strong scientists on point. After all, engineers left to imagine what’s possible without scientific guidance can come up with ideas that are . . . unorthodox? Unconstrained by reality? We can’t keep up with Europa science the way you can, Bob, and JIMO isn’t the only thing the lab has in the hopper for spacecraft concepts to get there. You’ve got to be ready. If Congress sends an extra billion dollars to NASA, the agency is going to ask for ideas. Let’s go to Venus or Pluto or Neptune’s moons, and you need something to slap onto the administrator’s desk. Glad you asked! We’ve been thinking about this one for a while! We’re all one big, happy space program, but it’s every NASA affiliate for herself. If Jet Propulsion Laboratory isn’t ready with the razzle-dazzle, Goddard Space Flight Center in Greenbelt, Maryland, or its neighbor, the Applied Physics Laboratory in Laurel, might get the gig, and then you’ve got a thousand Pasadena engineers on the payroll with nothing to design, build, or fly. And this we know: Once JIMO joins the choir invisible—it’s a dead mission walking, Bob—NASA is going to try Europa again. They’ll ask for a more manageable mission concept. And they want density, not volume. NASA headquarters knows science from science fiction.
Bob knew that a big part of the lab’s Europa program was science fiction—and not just JIMO. By 2004, JPL had spent money on such Europa concepts as “melt probes,” which would have required landing on an unmapped moon in a robot-broiling radiation environment and penetrating an ice shell harder than concrete and kilometers thicker than any hole ever drilled on Earth to reach an ocean that, technically, might not even exist.23 Good luck with that.
Even superb studies of plausible mission concepts had been unable to find traction at headquarters, as Bob knew firsthand. He had consulted briefly on a JPL study in 1998 for a possible spacecraft called Europa Orbiter—an outgrowth of an ambitious program called Ice and Fire—and it was a real contender. The project gathered momentum when the spacecraft Galileo got a good look at Europa’s tarnished crystal facade, and magnetometer measurements hinted at liquid water churning beneath its icy exterior. NASA convened a science definition team to establish the best science attainable with a small, sub-billion-dollar spacecraft. They determined that Europa Orbiter’s goal would be to answer the water question: Was it real? Or something else? Then, if it was real, the orbiter would map the ocean in three dimensions and, lastly, figure out why Europa’s surface looked like a cue ball scraped by a madman with a rusty nail.24 You do those three things, and you’re in good shape for a subsequent lander mission, a concept for which was already on the books. It was about the size of a pizza, the lander, but it would reveal an awful lot about the Jovian moon’s surface—e.g., was it solid or slushy?
Based on Jet Propulsion Laboratory’s promise of an inexpensive Europa mission able to overcome the historically ten-figure toll to cross the asteroid belt, in 1999 headquarters signed on and seeded the lab with fifty-eight million dollars to begin detailed development work.25 And once that money was spent, lab leaders came back to headquarters, all smiles and with a plan in hand that was twice the quoted cost—but, hey, you’re on board, right? And, hey, headquarters definitely was not, and Ed Weiler, the head of science missions for NASA, canceled it with prejudice.26
THIRTEEN POINT EIGHT billion years earlier—three minutes, in fact, after the universe began—hydrogen nuclei formed: good old atomic no. 1, the lightest element on the periodic table.27 Until then, space itself had been bounding outward from a single point to the entire observable univer
se. It cooled into a quark soup, quarks came together to form baryons, and electrons were new in town and turning heads.28 It was a busy three minutes. When hydrogen nuclei stepped onto the stage (though not into the spotlight—light as we see it didn’t exist yet),29 so too did those of helium, lithium, and beryllium (nos. 2, 3, and 4, respectively, though their parts were small indeed), and it took another four hundred thousand years of universal cooling before the nuclei could draw in those eligible electrons and form stable, bona fide atoms. Over time those atoms met, became gravitationally attracted to one another, and formed clouds in space called nebulae. A trillion galaxies or more formed from the clouds over the next nine billion years, and one of them was spiral-shaped and destined to be called the Milky Way.
Our nebula was not a particularly peaceful place, though it was stunning, from the outside far away and looking in: a celestial cloud of white, blue, beige, and burgundy, and it was very, very big—quadrillions of miles from end to end—just ridiculously large, really. All across the nebula, stars formed and exploded with unnerving regularity, contaminating the cloud with smithereens of stardust from which other stars and systems would emerge and expire and further enrich the ether.
It is how the elements beyond beryllium were born. A small star is a fusion-powered factory, its dense and powerful interior slowly squeezing together the nuclei of hydrogen atoms and turning out fresh helium. Fusion reactions let there be light. Larger stars do this on a scale commensurate with their size, and when their available hydrogen is used up, fused fully into helium, they double down on the whole process and start fusing helium to beryllium and carbon, and down the line to iron—our friend Fe, twenty-six protons now forced into a single atomic nucleus. And that’s as far as a star gets before all that iron and heat and pressure destabilize it, and it finally says forget it and explodes in a cosmic cataclysm. The resultant forces then really get to work on the atoms at hand, chaotically fusing and forming everything up to (and including) uranium, with ninety-two protons stuffed in its nucleus: our atomic bombs, fueled by supernovae themselves. And by now, the bulk of the periodic table is forged and scattered across the cloud, again and again and again, stars forming and failing and feeding the fertile miasma.
The Mission Page 2
