In the end, after the observations of the ancients and the meticulous mathematics of Kepler, after the comet-frescos of Giotto and the telescopic discoveries of Galileo, after Sputnik, Ranger, and all the far-flung probes of four decades of space flight – we have the stark, spectacular beauty of the spheres themselves. They’re real, verifiable. They move kinetically, inexorably. Grouped in wheeling archipelagoes, or sometimes alone, but always part of a larger system ruled by the sun’s gravity and light, they’re suspended in space like weightless jewels. Of the planets, most have moons. Of the moons, some are bigger than planets. Both moons and planets can have tenuous atmospheres, or incredibly thick ones, or none at all. Immense and banded, Jupiter is the largest by far. Flickering polar auroras, high-speed scudding clouds, and massive, whirling-dervish storm systems define its gaseous face. Jupiter’s powerful gravity insures that its innermost large moon, Io, is unstoppably volcanic and eerily lurid in its surface coloration. By contrast a second Jovian moon, Europa, is cool and off-white, a frozen, cue-ball perfect world. A third satellite, Callisto, has been ravaged by eons of meteor impacts; battered and pitted, it doesn’t look at all like either of its sisters. The proximity of the Jovian moons to each other only accentuates their odd-ball disparity.
Inwards and closer to the Sun than Jupiter, past the familiar blue glow of our home world, the hidden topography of cloud-shrouded Venus ripples and heaves with strange, protuberant forms. First discerned by the unwavering radar eye of the early 90’s Magellan space probe, they were quickly dubbed “ticks” and “arachnids” by planetary scientists, and are almost certainly the result of sub-surface volcanic activity. Meanwhile our other “terrestrial” neighbor, Mars, sports seasonal spinning dust devils; they trace spidery calligraphic streaks in the vicinity of Vallis Marinaris, the grandest canyon in the Solar System. As wide as the entire continental United States, this complex of vast and serrated desert walls was named after its discoverer, the 1971 Mariner 9 probe. And as if all this weren’t already enough, outwards from Jupiter in the direction of interstellar space, Saturn hovers like a hallucination. The shimmering ring system of the second largest planet are sixty feet thick, 155 thousand miles wide and comprised of innumerable boulders held perpetually in the grip of the rapidly spinning planet’s gravity. Saturn looks somehow designed – an object as perfect as the mathematics within the forces that made it.
How do we know about all this awesome scenery and clockwork motion? Because it has been photographed, scanned, and parsed by over a hundred robotic explorers from various nations – though primarily the United States and the former USSR (see http://www.solarviews.com/eng/craft1.htm) – using a variety of scientific instruments. (Interestingly, the word “robot” comes from the Russian “rabotnik,” or worker.) The sum total of the information which we’ve acquired in the brief forty years of space exploration so far outstrips all previous human knowledge of the Solar System as to make the comparison almost ridiculous – a dime-thin pamphlet next to a library of encyclopedias. And in the last decade these discoveries have continued cascading in exponentially. Less than two years ago, for example, NASA’s recently deceased Galileo probe revealed that Jupiter has up to nine tiny asteroidal satellites orbiting it close in. (That venerable spacecraft finally ended its fourteen year mission by diving into Jupiter in late September.) Within the last five years, Galileo also helped planetary geologists to deduce that the spidery network of cracks splayed across Europa’s ice face gives clear evidence of a subsurface liquid water ocean. The moon may even contain several times as much water as Earth – a prospect which inevitably raises the question of whether life could have evolved in orbit around Jupiter.
Other recent space probe findings concern Mars, and were conducted by the camera system of the Mars Global Surveyor and the thermal imaging system of another orbiting probe, Mars Odyssey. These two craft revealed that both distinctive gulleys and the thermal retention properties of parts of the Martian surface give evidence that this planet, too, most likely has liquid sub-surface water. Along with Europa, Mars is thus considered a potential host of extra-terrestrial life.
And this flood of revelations isn’t likely to stop anytime soon, despite NASA budget cuts and a crises in the agency due to the recent loss of Space Shuttle Columbia. In January of 2003, four probes from various nations will arrive at Mars, where they will join the two US orbiters currently on-station. Two new NASA missions will deploy rovers; a European Space Agency mission will leave an orbiter to circle the planet and send down a small stationary lander; and a Japanese mission called Nozumi will also go into orbit, resulting in a record-breaking seven spacecraft active at the Red Planet simultaneously. And in two years, one of the largest and most complex interplanetary spacecraft ever conceived, NASA’s Cassini, will arrive at Saturn after an eight year flight. This schoolbus-sized robot will study the planet’s rings and deploy a European-built probe called Huygens, which will penetrate the clouds of Saturn’s mysterious moon Titan. This opaque brown sphere appears to be rich in the same organic chemicals that presaged life on Earth; it may contain lakes, or even oceans, of liquid methane.
For much of the last decade I’ve been monitoring this activity as best I can, both by using the Internet and also by interviewing planetary scientists and the mission directors, navigators and engineers of NASA’s Jet Propulsion Lab. As a non-scientist with an interest in the visual arts, much of my motivation lay in simply being drawn to the more aesthetically compelling deep-space photographs. I was interested in pictures capable of inspiring awe, or wonder, and I believe I found them; many of these shots outstrip the wildest imaginings of 20th century science fiction (and yet they’re real).
I was helped in this research by the existence of large quantities of photographs on-line – either at public outreach websites like NASA’s excellent Planetary Photojournal (http://photojournal.jpl.nasa.gov/) or in more specialized scientific research sites. I started to log large quantities of time in the latter, and found myself going through many thousands of raw, unprocessed pictures, just for the sheer fascination of stumbling on previously unnoticed views of these alien topographies. Soon I embarked on a book project to document my findings – something which had the advantage of giving me both the funding and time to search for the most ravishing extraterrestrial landscapes I could find.
Almost all of the photographs in the resulting book, Beyond: Visions of the Interplanetary Probes, required substantial amounts of digital processing. Some had never been rendered into color before. Quite a few are multiple-frame mosaics, the result of finding remarkable contiguous single frames and collaging them together. Even the many shots which were picked up largely pre-processed frequently required hours of work to make them suitable for publication, either to modify their colors according to the best information currently available, or to remove seams between mosaic frames, or to clone over a speckle of uncorrected bad pixels or other transmission artifacts. (And some, of course, simply slid into place without needing additional work—a testament to their talented processors, who often remain anonymous, with their pictures simply credited to JPL or NASA.)
As this issue of Smithsonian goes to press, a small squadron of space probes are in development. These include Messenger, only the second mission to Mercury, which will fly past the planet twice before settling into orbit around it in late 2009 after a five-year flight, and the Pluto-Kuiper Express, which has fought its way back from cancellation and received funding for a 2006 launch to visit the Solar System’s farthest-flung and smallest planet. The Express will then proceed to a mysterious belt of cometary snowballs and—who knows?—abandoned alien spacecraft beyond Neptune, at the dim edge of interstellar space.
When they get where they’re going, these and other hardy robot explorers will continue doing what the other probes have: they’ll help place us in both space and time, changing our sense of our position and our possibilities, and revealing glinting and unexpected new vistas under the dazzling Sun.
September 23, 2003