Voyager: Exploration, Space, and the Third Great Age of Discovery
Page 19
Antarctica was an ideal venue—the geographic and historical transition from the Second Age to the Third. Its contrast with the Arctic expresses that status perfectly. The Arctic is a sea surrounded by land; the Antarctic, a continent surrounded by ocean. The Arctic, for all its hostility, harbors life around and under it, and to some extent on it, not just random organisms but functional if spare ecosystems. For the Antarctic, save trivial oases of exposed rock, life ends at the continent’s edge. Even more pronounced are their divergent human histories. The Arctic is encased by, accessible to, and hence bonded to, human history. It has its indigenous peoples, its imperial claims and colonizing epochs, its ancient economies of hunting, fishing, and trade. The Antarctic has none of this. No one has ever truly lived there; no enduring natural assets bind it to the world economy; no colonization or claims to sovereignty have global recognition. Its population is scientists; its trade, information; and only an immense expenditure of will and money has forged even these tenuous links. The Antarctic’s isolation is so complete that it seems less an intrinsic feature of the planet than an extraterrestrial presence accidentally slapped onto its surface, as though an icy moon of Uranus had slammed into Earth.
It is a place that is isolated, abiotic, acultural, and profoundly passive. One goes there in defiance of natural impulses. The scene reflects, absorbs, and reduces. It acts as a geophysical and intellectual sink. It takes far more than it gives. With implacable indifference it simplifies everything: that is its essence, the synthesis of the simple with the huge. It reduces an entire continent to a single mineral taller than Mount Whitney and broader than Australia.
The scene acts on people as it does on other earthly features. There is no genuine society. There are no children, no families, no schools, no social order, and no matrix of interlocking institutions. It is more like a mining camp or those shore-based trading outposts typical of the First Age. But worse: at least the residents of earlier outposts could intermarry with indigenous peoples, and the resulting mestizo societies—pioneered, as so much of European expansion was, by Portugal—did the heavy work of exploring and settling the interiors of South America and southern Africa, and of parts of south and southeast Asia. Exploration meant a transfer of knowledge from one group to another; explorers relied on native guides, translators, hunters, collectors; and they typically adopted native clothing, if not native mores. None of this was possible in Antarctica. Yet without such cultural contact and without a true social setting there could be no great literature or art. The ultimate Antarctic saga is Douglas Mawson’s solo trek, slogging alone across broken ice fields, with no guide and little direction, nothing to record but conversations with himself, nothing at all but his own will to continue.
To this sketch there are seeming exceptions. Chile maintains a small army base, complete with families, on King George Island. The Southern Ocean swarms with krill, fish, seals, whales, and penguins. There are microlichens on some exposed rocks, and bacteria in sandstone and perhaps under the ice sheet itself. Tourists visit sites on the peninsula annually. But all these activities occur along the continental fringe, or on minor outcrops along the margins or, in the case of the Chilean base, on an island outside the Antarctic Circle (roughly equivalent to the latitude of Helsinki). The social order, often quasi-military, is akin to that of a ship, quite independent of place. America’s McMurdo Station is not a Plymouth colony but a Virginia City, and Amundsen-Scott South Pole Station not a St. Louis but an icy St. Helena. Biotic fragments do not make a sustaining ecosystem. The Antarctic analogy begins only when you cross the barrier ice and step onto the ice sheet. Then you enter the Third Age.
The Antarctic analogue suggests that the Third Age will be dominated by near-Earth terrains. Exploration will happen through remote sensing and robots. Outposts may be permanently established but not permanently staffed, their inhabitants coming and going routinely, like migratory flocks or marching penguins. They will traffic in the luxury goods of an information society. The requisite rivalry that must power exploration will probably derive from the competitive character of science itself, conducted as a cultural pursuit with national prestige, not national survival, as its payoff. It will mean, in a curiously postmodernist way, talking with ourselves.
These traits identify Antarctica with the Third Age. Some of them are more intensely manifest on the Ice than elsewhere. Mars is richer in information; the Canary abyss far lusher with life. But Antarctica is accessible to people at relatively little cost compared with space travel, and can be seen without the extraordinary cocoons that shield the senses of human travelers from the environment. You can breathe on the East Antarctic plateau without special oxygen tanks. You can smell, taste, touch, and hear, as well as see (there just isn’t much to smell, taste, touch, or hear). In the abyss and in space, only sight is possible, which is why robots and instruments can seamlessly replace human observers. It remains to devise programmable computers to similarly guide mechanical hands and supplement, if not supplant, the respiring brain.
To partisans of space settlement, the Antarctic analogue is a glass half full. It is the beachhead for a more remote and complex colonization. To critics, it is a glass as full as it will ever become. They note that humans have wintered over in Antarctica for more than a century and that the dynamics of such outposts have not changed significantly. For them, a Voyager, not a base at Dome C, is the future of geographic discovery.
ANALOGY’S END
Analogies fill in what we don’t know. They are a form of social anticipation, of prophecy or prediction. Understanding abhors vacuums as much as nature. Certainly that adage has applied to the vacuum of space.
As Voyager moved from idea to machine to functioning spacecraft, analogies buzzed around it, all forecasting what it might do, might become, and might mean. But once it began its tasks, those analogies faded; the mission moved from prediction to history. Voyager was poised to become itself a source rather than a recipient of analogy. It was no longer something to be imagined but rather an event recorded and a source of hard data.
In June 1978 Voyager 1 began transmitting photographs of Jupiter, followed by increasingly dense recorded radio emissions, plasma wave data, and other readings. On December 10, 1978, still eighty million kilometers from Jupiter, Voyager 1 transmitted photos of the giant planet that exceeded in detail and color any ever taken from Earth.
DAY 491- 681
12. Encounter: Jupiter
Planetary encounter—this is what Voyager was made for. Jupiter was the first, and it established the pattern of sequenced phases: observation, far-encounter, near-encounter culminating in periapsis, post-encounter. That ritual cadence, with modifications, like a slow spiral of activities that quickened with approach, would repeat six times across the outer solar system. Voyager 1 initiated that astonishing series, achieving its closest approach on March 5, 1979.
Preparations began while the Voyagers were still cruising. There were course corrections, as always, and in late August 1978 both spacecraft received new programming intended to sharpen the performance of their imaging systems. In early November, a month after Voyager 2 cleared the asteroid belt, flight controllers commenced training exercises, some four months before nearest encounter. A paradox of planetary exploration was that discovery depended on an intricate scenario of preplanned maneuvers that determined the exact trajectory, decided what instruments operated for how long and in what sequence, and arranged for when data was downloaded—all this calculated to the minute or even to seconds over a 39-hour period that constituted nearest approach as an accelerating spacecraft hurled toward Jupiter at 46,000 kilometers per hour and was flung away at 86,000 kilometers per hour. Such detailed choreography required precision drilling. A rough rehearsal followed on December 12 through 14.72
The next day Voyager 1 left its cruise phase for its observatory phase.
VOYAGER 1
Observation commenced officially on January 4, 1979. There was some flexibility as to when
it might actually begin, and once tasks were uploaded, the spacecraft could do its chores with or without close ground supervision. Originally, observation had been scheduled for December 15, but the holidays complicated matters, so rehearsals had been moved up and the official opening slipped back. This left Voyager 1 still some sixty days out from Jupiter.
Beginning on January 6, Voyager took photographs of the planet every two hours; from January 30 to February 3, it began photographing every ninety-six seconds, and did so over a one-hundred-hour period, until Jupiter became too large for its narrow-angle camera. For the next two weeks, photos came in sets of two-by-two pictures, and by February 21, three-by-three images, later assembled into mosaics. Meanwhile, Voyager directed its other instruments—the ultraviolet spectrometer, the infrared spectrometer, the polarimeter, instruments for planetary radio astronomy, and plasma waves—to absorb, scan, and record.73
The milestones rushed by. Ground crews waited anxiously for the bow shock, the ionic reef of Jupiter’s magnetosphere. On February 10 Voyager entered into the realm of the Jovian system, crossing the orbit of Sinope, the outermost moon. On the seventeeth it photographed Callisto, and on the twenty-fifth, Ganymede. It was now scanning images every forty-eight seconds, and instruments were recording auroras, ion sound waves, and the shifting shoreline of the magnetosphere. The real payoffs, though, would follow periapsis as Voyager made close flybys of the Galilean moons. Scientists and the press began converging on JPL. On February 27, with Voyager some 7.1 million kilometers from Jupiter, public TV in the Los Angeles area began broadcasting a “Jupiter Watch” that allowed the public to view virgin images at the same time as mission scientists. On the twenty-eighth Voyager finally felt bow shock, and time-lapse movies revealed the mechanics of the Jovian atmosphere and its star performer, the Great Red Spot. On March 1, now 4.8 million kilometers away, Voyager crossed the magnetosphere, and photos of the distant satellites were released. The next day heavy rain at the Canberra Deep Space Network site blocked signals for several agonizing minutes, but ever more detailed images continued: the eyes of discovery belonged to anyone with a TV set. On March 4, the eve of near-encounter, Caltech hosted a symposium on “Jupiter and the Mind of Man.” There was surprisingly little to engage, for Jupiter had never commanded interest comparable to that of Mars or Venus. Within hours, however, its cultural clout would change.74
Closest encounter came at 4:05 a.m. PST on March 5, 1979, some 780,000 kilometers from Jupiter, at a velocity of 100,000 kilometers per hour. The message took thirty-seven minutes to reach JPL. Voyager 1 now flung about the planet for what would be a survey of Jupiter’s satellites. It crossed the orbits of the Galilean moons, one after another, and that evening took a full-frame sequence of Io. A failure at the Madrid DSN station caused a gut-wrenching loss of fifty-three minutes’ worth of data, and an hour later, another eleven minutes washed away. Meanwhile, as Voyager passed through Jupiter’s equatorial plane, it focused its cameras on the space between the gaseous clouds of Jupiter and its tiny rock of a moon, Amalthea. Three days later, analysis confirmed that Voyager 1 had discovered an unknown ring. Now Voyager trained its cameras on Io. At 8:14 a.m., having completed its gran volta, the spacecraft disappeared behind the giant planet. For an anxious two hours and six minutes, invisible on the far side of Jupiter, it could only store data, before broadcasting its hoarded information back to Earth when, an hour later, having made its closest approach to Europa, it emerged from the shadow zone altogether. Before the day ended it passed by Ganymede, and the next day, March 6, it flew by Callisto. Two days later encounter officially ended, and as JPL shut down the daily press briefings, project scientist Ed Stone said simply, “I think we have had almost a decade’s worth of discovery in this two-week period.”75
The cavalcade of wonders had stunned nearly everyone. Voyager had photographed a gallery of Jupiter’s inner moons, each of them revealed as a “different world.” There was Io, pocked but uncratered; Ganymede, cratered but also grooved, apparently through faulting; Amalthea, an asteroid-like body; Europa, smooth with ice and mysteriously dark-streaked; and Callisto, icy, densely cratered yet also smooth and boasting the “largest single contiguous feature” yet discovered, an immense impact crater named Valhalla. Reviewing data, scientists quickly confirmed a Jovian ring; and other, more arcane analyses tumbled out. On March 8, as encounter concluded, Voyager looked back again on Io, now a luminous crescent against the Sun. The intent was mundane, an exercise in navigational backsiting. Within several days, however, the photo became the canonical image of Voyager 1 at Jupiter. In that unexpected outcome the episode might well stand for the entire encounter. 76
Jupiter is a miniature solar system. It is a gaseous planet with a diameter of 142,800 kilometers, one tenth that of the Sun but more than ten times that of Earth. It features the dual geography of the solar system, the hard field of planets and gravity and the soft field of electromagnetic radiation and ionic gases. It has moons the size of small planets, each distinct. It has a magnetosphere to complement the Sun’s. The instruments Voyager carried could measure them all.
Both realms are dynamic, both held surprises, and Jupiter warped each. In its soft geography, researchers found lightning whistlers, mapped the rude dimensions of the Jovian magnetosphere, calculated radio emissions, documented plasmas of various ions, identified the source of exceptional radiation (sulfur from Io), and plotted the magnetic torus around Io. The dominant topic was the magnetosphere, where Jupiter’s electromagnetic energies collided with the Sun’s to power a kind of invisible weather of strong radiative winds and rough magnetic seas. If rounding Jupiter was akin to doubling the Cape of Good Hope, then it is worth recalling the cape’s original name, the Cabo das Tormentas, the Cape of Storms.
The magnetospheric border between the Sun and Jupiter was fluid and blustery; it was not where Pioneer 10 had found it; and when Voyager 1 did cross that frontier, the spacecraft had to pass through its electromagnetic shoreline, buffeting against ionic white-caps and tides, not once but five times, as violent solar winds pressed and pushed against their strenuous Jovian rivals. The radiation blast, despite hardening against it, was sufficient to damage parts of Voyager 1’s payload, notably its clock and the synchronization of the two central computers, with the result that the camera and scan platform operated on a schedule some forty seconds apart. What should have been some of the highest resolution images of Io and Ganymede returned blurred.77
Even where fuzzy the images of Jupiter’s hard geography were what gripped public imagination. Here was revealed, for all and at the same time equally, amid a collective public gasp, the character of new worlds. While there was no solid surface to survey, Jupiter’s fluid, multicolor atmosphere was ready-made for time-lapse movies. Here was the weather of another planet, all recorded in gorgeous Technicolor. Hurricanes the size of Earth’s Moon that lasted for centuries; stormy eddies that roiled past like boiling Mississippis; trade winds that would shred and crush sailing ships; cloud depths that could vaporize comets. As Voyager approached, and the images sharpened, the Great Red Spot became a cosmic celebrity. A photo of tiny Io against the backdrop of overweening Jupiter spoke volumes about the majesty of the Jovian system and the awesome scales of planetary discovery. With its Mondrian hues and Pollock swirls, Jupiter became a gallery of abstract, modernist art.
But it was the inner satellites that ignited what evolved into a Voyager mystique. Unlike gaseous Jupiter, they were hard bodies, and could be imagined by analogy to familiar moons and planets. As Voyager 1 trained its cameras on them, everyone could sense that these were, as mission geologist Larry Soderblom observed, “new worlds” ready for discovery. Yet none resembled Earth or its Moon, or even Mars or Venus. None looked like the others. Amalthea, Io, Ganymede, Europa, Callisto—each had its own geological evolution, and operated on principles unlike those of the Sun’s inner planets. The images were fresh, startling, spellbinding. The geology they exhibited was, at first sight, inexplicable.
VOLCANOES
As Voyager whisked beyond Jupiter, it turned and took one parting shot of Io, now 4.5 million kilometers away and a luminous crescent against the deep black of space. It was a long-exposure image intended for use with its celestial navigation system.
In processing the image, Linda Morabito, a member of the optical navigation group, noted an anomaly. A domelike cloud seemed to bubble up from the surface. Yet Io had no atmosphere. Others, meanwhile, had also spotted and begun to ponder the image. An independent discovery by John Pearl of the IRIS team led to a consensus conclusion: Voyager 1 had witnessed a volcanic eruption. An investigation of all the images over the next week identified eight such events. Io in eruption became the defining image of Voyager’s encounter with Jupiter.79
Suddenly a dozen inexplicable oddities about the Jovian radiation belt made sense. Its exaggerated intensity and the sulfuric emissions recorded by ultraviolet instruments were the result of sulfur ions blasted into it by Io. Geologists now had an explanation for the moon’s weird colors, hot spots, and gaseous bubbles. Instead of impact craters, Io had massive calderas. Io was nothing like Earth’s Moon, inert and cold. It was far removed from the dead bodies expected to litter the outer solar system, far distant from what theory had predicted. Subject to Jupiter’s immense tidal bellows, Io warmed, melted, and blew off eruptions of sulfur that entered into and altered the magnetosphere. At Io the hard and soft geographies of the solar system collided with a display of planetary fireworks.