Farewell Fantastic Cassini
Machine into meteor: Cassini's last encounter. © NASA Jet Propulsion Laboratory |
But while the previous visitors had snatched glimpses of the planet and its rings and moons as they shot through the Saturn system on their way to other places, Cassini went into orbit. Settled in. Made the place its home for thirteen years, guided by its flight engineers in intricate loops that took it close to all the major moons, eking out its fuel by gravity assists during close encounters with Saturn and its biggest moon, Titan. Cassini's discoveries and beautiful images of the planet, its rings and above all its moons, immeasurable inspired, enriched and deepened my writing. We make up worlds all the time in science fiction. But here were real worlds as weird as any ever conjured by imagination; real landscapes. Some of those landscapes were - startlingly - like those of our own planet; others were utterly different. Places where people might settle one day - but who would choose to live there, and why? How would it shape and change them? I wrote those two novels to find some answers to those questions, and Cassini helped to bring those wildly strange and various worlds into sharp focus.
Launched in 1997, it arrived at Saturn, one and a half billion kilometres from Sun, in September 2004, its transit time shortened by slingshots around Venus, Earth, and Jupiter. A few months later, the European Space Agency's Huygens probe detached from Cassini and in January 2005 landed on Titan. The first landing on the moon of a planet other than Earth; the most distant landing ever made. And for the first time we saw the surface of Titan: glimpses of mountains cut by branching riverine channels as the probe descended through the thick nitrogen atmosphere and a haze of hydrocarbon smog; a fixed view of the marshy surface, strewn with pebbles, of the shoreline where it touched down.
Frozen beach. © European Space Agency |
Mapping and observing Titan's surface was just one of Cassini's achievements. It has discovered more than a dozen tiny moons and moonlets. Shown that the ring system is active and dynamic, an intricate dance of icy particles and shepherd moons and gravity; helped to solve the mystery of why one hemisphere of the moon Iapetus is dark, and the other is ice-bright. And it has not only shown that the little inner moon Enceladus is active, jetting plumes of icy dust from crevices in its south pole that access an inner sea or ocean of liquid water; it has also flown through and sampled those jets, discovering that they contain the ingredients necessary for life.
Jets. © NASA Jet Propulsion Laboratory |
And now, after hooking around Titan for the last time, the spacecraft is heading inwards. Heading towards its final, fatal encounter with Saturn, on Friday. It will go out transmitting a live feed. Doing science until it breaks apart, the sharp end of a great human enterprise of enquiry and discovery. Mourn the machine, but celebrate that achievement, which has accumulated data and images that will be analysed and picked over for years to come. A lasting legacy that's given sense of shape to things formerly unknown, and names and local habitation to places barely glimpsed, or never before seen. Ave atque vale!