On the evening of November 6, Voyager 1 underwent a final course correction—its ninth. The maneuver was doubly complicated because the Canopus star tracker had earlier malfunctioned, but controllers were confident that onboard redundancies would compensate. The spacecraft tilted 90 degrees, fired its rockets for 11.75 minutes, and took almost four hours before recovering sufficiently to transfer control to its gyroscopes back to celestial tracking. With its new trajectory it could speed past Titan, dip below the southern pole of Saturn, and then rise back up through the ecliptic of not only Saturn but also the Sun, and race away to the edge of the solar system. For the most part, Voyager 1 also determined Voyager 2’s passage; but for now its remote, trailing twin assisted its sibling by measuring the strength of the approaching solar winds (which were high), thus allowing for better forecasts of when Voyager 1 might encounter bow shock, the turbulent, filmy border between the solar wind and the Saturnian magnetosphere. Meanwhile, the plucky spacecraft took a snapshot of Iapetus .108
What mattered was less the Sun’s weather than Earth’s. Thunderstorms pummeled Madrid and blocked out transmissions to its DSN tracking station for some six hours. Not until the Goldstone station, in California’s Mojave Desert, acquired a signal could data return. When it did, Voyager revealed another new moon—the third it had discovered at Saturn—and yielded more information about the rings, Titan’s atmosphere, and Saturn’s magnetosphere. On November 9, sharpened images only heightened the mysteries of the rings and their spokes and of the anomalous absence of upstream bursts of electrons such as happened at Jupiter. But photos of Rhea promised another gallery of new satellite worlds. And of course there was Titan, as large as Mercury. On the eve of near-encounter, the panel of planetary wise men reassembled once more, as they had for Mars and Jupiter, to discuss “Saturn and the Mind of Man.”109
On November 10, the air was electric with expectation. Voyager 1 would pass through Saturn’s bow shock and fly past Titan, but veteran scientists and journalists readied to undergo their own bow shock of novelties. In what had become a mantra, researchers repeated that “Everything we are seeing on Saturn is brand new.” That, in truth, is exactly what the partisans of Pioneer 11 had proclaimed, and both were right. Voyager saw more and saw more clearly, and it encountered a differently tilted Saturn, so that even when it revisited themes, it found them altered or it reexperienced them as though for the first time. Moreover, what Voyager had found at Jupiter did not, uninterpreted, translate to Saturn. The two planets, or planetary mini-systems, more resembled each other than they did Venus and Mars, yet they differed no less than did the inner planets. The discoveries were as fresh as the Bahamas in October 1492, or Antarctica in January 1840. The images scrolled past: Tethys, Dione, Rhea; the befuddling and mesmerizing rings; the muted weather of Saturn. Still maneuvering, Voyager acquired a new guide star while its far-encounter rapidly closed.110
The measurements, the images, the outburst of data—all rushed forward on the eleventh with the quickening pace of the spacecraft. For Voyager 1 there were in reality several near-encounters. The first was with Titan, some eighteen hours prior to its near-encounter with Saturn proper. As it whooshed toward Titan, the giant, enigmatic moon overflooded Voyager’s narrow-angle camera, demanded three-by-three mosaics, and absorbed almost all the spacecraft’s scans. Yet Titan refused to part its lofty haze; its surface remained opaque, and Voyager was forced to rely on indirect instrumentation, especially a double occultation, once as it passed behind Titan, and again after it passed out the other side. With that telemetry came the calculation that trajectory deviated from the programmed schedule: the distance, two hundred kilometers, mattered less than the timing, some forty-three seconds. (Engineers scrambled to recalibrate the sequencing before closest encounter.) Even as it swept beyond Titan, Voyager glided through the Saturnian ring plane and approached periapsis from beneath and on the dark side of the planet.111
On November 12 the countdown to closest encounter began with photographs of Tethys, the dark side of the rings, then Mimas and Enceladus, and the co-orbital satellites, S-10 and S-11, that Pioneer hinted at but never saw, followed by an occultation of Saturn and passage to its dark side, an encounter with Dione (which it was hoped would sweep the region clear of ring debris), followed by an exit occultation and reemergence from Saturn. Telemetry twice zipped through the atmosphere of Saturn and, ninety minutes later, danced dangerously with thunderstorms at the Madrid DSN station; but the signal came through. Still within Dione’s presumed clear zone, Voyager 1 passed upward through the ring plane. Soon afterward the spacecraft made its closest approach to Rhea.
Everyone watching was stunned, and overwhelmed. They were “euphoric,” exhausted, but mostly “simply flooded with new data.” There was too much, and there was too much new, and too much that didn’t fit theories and preconceptions. In this “strange world,” as Bradford Smith, head of the imaging team, commented, “the bizarre” had become “the commonplace.” He spoke particularly of fresh images of an F Ring, eccentric and braided in defiance of gravitational mechanics. But almost everything about the Saturnian system had either blurred Voyager’s instruments with a gauze of haze or, if it sharpened the image, only deepened the haze of understanding. Tiny Mimas had an impact crater almost half as large it was. Tethys had a near-encircling trench. Dione hinted at internal forces. Enceladus lacked mighty craters. Iapetus had contrarian dark and light surfaces. Rhea boasted a new saturation level for impacts, all the more astonishing for what was essentially an icy rock. Saturn’s inner satellites, all five, constituted “ice planets,” an “entirely new class of worlds never before seen.”112
The data analysis continued, even as Voyager turned to photograph and measure a receding, crescent Saturn. That image—Saturn’s shadow streaking across its luminous rings—would be Voyager 1’s Saturnian signature, as Io’s volcanoes had been its Jovian. When the encounter phase officially concluded on November 13, Voyager continued to scan the scene, looking for new moons, viewing Saturn from fresh angles. It now sailed above the ecliptic, headed away from not only Saturn but also the planets altogether, for a final encounter with that nebulous boundary where the Sun’s wind collided no longer with planetary magnetospheres but with those of other stars.
TITAN
Saturn’s shadow had not been the expected dominant image of Voyager’s encounter. That honor had been reserved for Titan, for it was hoped that Voyager 1 might penetrate the veil of Titan’s atmosphere. It didn’t.
From the earliest planning, Titan had loomed as a primary target. The desire for a close flyby determined the entire trajectory of Voyager 1, which is to say, the Voyager mission overall, because going to Titan meant departing the planetary ecliptic altogether. But Titan was a world in itself. Its size, nearly as large as Mars; its atmosphere, denser than Earth’s and rich in methane; its proximity to Saturn, with the promise of magnetospheric dynamics between the two—all suggested that, in the words of Project Scientist Ed Stone, “an encounter with Titan” would be “the equivalent to a planetary encounter.”113
It would, so enthusiasts noted, perhaps be equivalent to visiting an early Earth, and a world more likely than any other to have life, or at least its predecessor organics. Voyager carried those hopes and queries to the planetary borders of Titan. A week before periapsis with Saturn, the spacecraft began an imaging sequence that, with computer enhancement, allowed some hint of contrast and perhaps of surface structure. But even with false-color imaging and other tricks, Titan remained impenetrable and inscrutable. Instead of contrasting with the generally bland surface of Saturn, Titan recapitulated it. Its size overwhelmed Voyager’s cameras, forcing imaging into two-by-two mosaics, and then three-by-three; there was no break in the clouds, only at best a computer-forced glaze of gloom. The cameras that had proved so illuminating on hard-surface satellites could here show close up only what telescopes had viewed from far off. The gauzy sheen screened off detail. The best that close scrutiny could discov
er was a haze layer, detached and hovering over the north pole, some one hundred kilometers above the impermeable primary atmosphere. The interrogation of Titan fell to instruments operating outside the spectrum of visible light.114
These did as they were programmed to do. The infrared spectrometer (IRIS) mapped heat, the ultraviolet spectrometer (UVS) scanned for higher-energy wavelengths, while radio astronomy tested occultation through the Titan atmosphere, and plasma wave detectors traced the anticipated interaction of magnetospheres between Titan and Saturn. (Titan, it was discovered, lacked a magnetic field.) But there was no surface to view, and there would not be until a radar imager could be sent to penetrate the clouds. Titan shied away from offering a tangible new world, presenting only an enigmatic mist-shrouded isle to taunt and tempt.
Instead of revisiting this unpromising scene, Voyager 2 would tweak its trajectory away from Titan and toward the equally baffling but far more transparent rings.
Had those hunkered down in the windowless mission center at JPL been able to look outside, they might have found the contrast between Earth and Titan that eluded them on their monitors. As the Saturn encounter wound down, Santa Ana winds had picked up, threatening the DSN antennas at Goldstone as thunderstorms had those at Madrid and compelling JPL to rely on backup generators to ward against power failure. More strikingly, the San Gabriel Mountains were aflame.115
Titan’s most passionate partisans were those obsessed with its organic chemistry and the prospects for life, or at least life’s biochemical progenitors. Titan was Mars with methane. Voyager revealed that its atmosphere was 1.6 times as dense as Earth’s and that nitrogen was, as with Earth, a major constituent. Titan offered a tantalizing prospect for a world in which methane took the place of water on Earth, with methane clouds, methane rain, and methane seas; but mostly it teased with the hope that a fluid soup of organics might reveal the cosmological foundations for life. It would offer that comparative alternative that would move life from a singularity to a statistic. What the Galapagos Islands did for the theory of evolution by natural selection, Titan might do for exobiology.116
That is what made those back-lot fires significant. At the time the prevailing portrayal of free-burning fire held that combustion was solely a chemical reaction shaped by physical circumstances, and that it mattered ecologically because it had been on Earth since the earliest terrestrial plants. It was a physical disturbance like hurricanes and ice storms, and affected the living world similarly. While everyone agreed that “life” elsewhere would not look like life on Earth, there had to be common features, much as the atmospheres and rings of Saturn and Jupiter, so seemingly alike, were different, and a general theory of planetary atmospheres had to accommodate both. So it would be with a theory of life. It would have to embrace both Earth and Titan. Earth chauvinism would falter before the challenges of the planetary Other.
Yet increasingly it is the conception of earthly life that has changed, a reformation for which fire may trace the emerging contours. The realization slowly grows that fire on Earth is biologically constructed; that life creates the oxygen, that life creates the hydrocarbon fuels, that life in the hands of humans is the primary source of ignition, that the chemistry of combustion is a biochemistry, joining the mitochondrial Krebs cycle to the cycle of flame in chaparral. Unlike floods, earthquakes, volcanoes, or the Santa Ana winds—all of which can happen without a particle of life present, or even shards of preorganics—fire cannot exist apart from its living matrix. Fire literally feeds upon biomass.
The fires that ripped across the San Gabriels offered an insight into earthly life far more vivid than abstract appeals to hydrocarbon drizzles and smoggy screens in the upper Titan atmosphere, and they threatened not so much the electrical power that ran JPL monitors as the conceptual power that underwrote what those monitors were designed to search for. Life was indeed more pervasive and exotic than prevailing formulas allowed; but the challenges to those views would likely come from Earth. They would come when new eyes viewed seemingly old worlds afresh.
This is what exploration by Western civilization had always done. From time to time it revealed truly unknown places, but mostly it discovered places known to others or rediscovered once known places in novel ways. The Indies—the destination of the First Age—were hardly unknown: the whole point of the Great Voyages was to find a new way to get there. Charles-Marie de la Condamine surveyed the Amazon with a map in his hand produced by predecessor Jesuits, and Humboldt succeeded La Condamine in Ecuador; while across the globe the Institut d’Egypte, accompanying Napoleon’s invasion, measured monuments known for thousands of years, yet saw them anew, and rendered them from obscurantist reliquaries to the measured and catalogued artifacts of science. The Second Age, after all, had begun in Europe as well as the Pacific. It was in Europe that the natural history excursion, the Grand Tour, and the new geology converged before Joseph Banks and Louis-Antoine de Bougainville took them global.
Sometimes discovery can come not by looking farther and deeper but simply by turning around.
THE PLANETARY SOCIETY
On the eve of Voyager 1’s closest encounter, as had happened with Mariner 4 and Viking at Mars and with Voyager at Jupiter, a panel, now well versed in the venue, convened at JPL to discuss “Saturn and the Mind of Man.” Chaired by Walter Sullivan of the New York Times and the author of books on IGY and Antarctica, the panel included Bruce Murray, Ray Bradbury, and Carl Sagan, all veterans of previous encounters, and Philip Morrison, returning from a stint with the Viking landing panel. Framing the session were comments by Marvin Goldberger, president of Caltech, and Jerry Brown, governor of California.117
The themes identified the usual suspects: imagination, curiosity, wonder, the imperative to understand our place in the cosmos. All combined science with other themes. The physicist Morrison added an emphasis on the aesthetic qualities of Saturn—its enthralling rings. Geologist, and now director of JPL, Murray commented on Voyager as a “climax of a glorious decade of exploration” and as the vanguard of a necessary era of discovery by robots. There was no alternative to semiautonomous spacecraft: the distances were too great and the velocities too speedy to allow for hands-on guidance from Earth. Astronomer Sagan managed to mingle the scientific with the prophetic, a kind of modern astrology purged of its hocus-pocus.118
Afterward the panel, along with many others, retired to a fund-raising dinner on behalf of The Planetary Society, which Murray, Sagan, and Louis Friedman had just founded. Its originating purpose was to rally public sentiment on behalf of space exploration by providing an institutional focus for such enthusiasms, one that could speak to politics. Its stated mission: “to promote planetary exploration and the search for extraterrestrial life.” By the time the organization celebrated its twenty-fifth anniversary, that charter had expanded to read: “to inspire the people of Earth—through research, education, private ventures, and public participation—to explore other worlds and seek other life.”119
That private groups might sponsor expeditions or, more commonly, pressure governments to do so had ample precedent. In the Second Age it was possible for individuals or small groups simply to trek to the frontier and walk into the unknown. But the Great Voyages, and certainly space exploration, were vastly too expensive for private capital, or, if undertaken, came with generous concessions.
Somewhere the state would be involved as not simply a tithe collector but a player concerned with the shifting balances of power that exploration might catalyze. While Prince Henry could mingle public and private enterprise, most rulers preferred to outsource discovery to individuals or Companies of Adventurers. Cabot and Columbus, for example, could establish themselves as medieval barons on new lands, provided they ceded a fifth of the discovered wealth to the state. In this way private groups took the risk, and the state collected money and power. Later, scientific societies supplemented commercial institutions and campaigned for expeditions; think of the Paris Academy dispatching Maupertuis and La
Condamine to measure an arc of the meridian, or botanical gardens sponsoring collecting naturalists, or the Royal Geographical Society and National Geographic Society sending exploring parties (usually under naval officers) to the ends of the Earth, from Lt. Verney Lovett Cameron to central Africa to Lt. Robert Peary at the North Pole. More recently philanthropy and publicity have combined to loosen the purse strings of private benefactors, leaving Antarctica, for example, endowed with the Beardmore Glacier, the Ford Mountains, and the Walgreen Coast. The idea that the state should undertake such enterprises for the sake of curiosity is a very recent innovation tied to the peculiarities of modern science and the perceived imperatives of national prestige as a subset of national security.
Perhaps the closest analogue to the Planetary Society was the African Association, or in its more fulsome title, the Association for Promoting the Discovery of the Interior Parts of Africa, organized in 1788 with Joseph Banks as chair. At the time, Banks was probably the best-known British scientist identified with exploration, was an aristocrat well placed in British society and scientific institutions (including Kew Gardens and the Royal Society), and was a keen promoter of geographic discoveries. The African Association targeted particularly a place of popular, even mythological lore, Timbuktu, and its associated river, the Niger. Under its auspices Mungo Park made two ventures to the region (the second proved fatal). More than sponsoring treks, however, the African Association kept the image of Africa and the putative value of its geographic exploration before the public eye and in the corridors of power. It lamented, as the Planetary Society did, the lapse in official enthusiasm after Park’s disappearance, and it struggled institutionally after its most charismatic figure, Banks, died. It was succeeded by the Royal Geographical Society under Roderick Murchison, which bridged official and unofficial exploring as Britain lurched into imperial competition with France and later Germany during Europe’s unseemly “scramble for Africa.” (It was in turn succeeded in space exploration by the British Interplanetary Society.)120
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