An ancient philosopher from Earth once suggested that humanity’s defining characteristic was that it could not resist stamping its footprints into pristine unspoiled ground. There was no good reason, for instance, why anyone would want to live on Prometheus, the shepherd moon that orbited just inside the narrow, twisted rope of Saturn’s F Ring, the outermost discrete segment of the gas giant's glorious ring system. Prometheus was a lumpy, irregular cylinder of dirty water ice about a hundred and thirty-five kilometres long and sixty to eighty kilometres across. Porous, lightly scarred by impact craters, blanketed by drifts of bright ice dust stolen from the F Ring, it possessed no useful resources, and its chaotic orbit meant that it was difficult to reach. Even so, a crew of gardeners stabilised one of its shallow valleys with a muscular mat of fullerene strands and tented it with diamond composite, and quickened a homeostatic microgravity ecology of spinweed, air kelp, and hypertrophied bryophytes. A famous poet lived there for a year; two different but equally short-lived tribes of utopianists briefly colonised it; it became a way station for the occupying force at the height of the True Empire; much later, an ascetic hermit took up residence, and captured the restless fluctuations of the F Ring in an ever-changing symphony.
At its closest approach, Prometheus’s gravity warped the F Ring’s icy material into waves and streamers, ploughing temporary dark channels into the strand of icy shards and dust that spiralled around the central core. The F Ring’s other shepherd moon, Pandora, also perturbed the ring as it orbited the outer edge, and hundreds of snowball moonlets swung around the ring too, passing through its inner core whenever their orbits were perturbed by Prometheus and creating temporary jets that extended for hundreds kilometres. The ring shivered and shook, plucked by gravity and ponderously slow impacts.
The hermit injected several million self-replicating probes into the ring, wrapped in photosynthetic sheaths and equipped with detectors that emitted signals that fluctuated in response to minute changes in velocity and trajectory. A chamber in the tented garden on Prometheus translated the sum of millions of oscillating signals into sounds analogous to those generated by Tibetan Singing Bowls; some ten years after she died, a rare visitor to the tiny shepherd moon discovered the hermit's desiccated corpse there, her music still huming and chiming in the luminous air.
The so-called Eternal Symphony of the F Ring was briefly famous. Pilgrims came to Prometheus from all over the Solar System to float in the chamber and submerge themselves in the oscillating drone of the ring, the deceptive cadences and eerie glissades of the warps created by Prometheus’s orbit, the rumbling percussion of colliding moonlets and the chiming clatter of the resultant jets. There was a brief fashion for apoapsis parties in which afficionados gathered to bathe in the atonal and violent passages created when Prometheus passed close to the F Ring, but like all fashions this soon faded. A century after the hermit’s death, hardly anyone visited Prometheus anymore, and the mirror feeds of the Eternal Symphony on various moons of Saturn, on Earth and Mars, in various cities of the Belt, were either disconnected or languished in forgotten corners of libraries.
Perhaps it would be rediscovered one day; or perhaps all trace of it would vanish from humanity’s collective memory. It did not matter. The symphony played on regardless. The probes manufactured new copies to replace those lost to time and chance; the semisentient chamber repaired and renewed itself; Prometheus and Pandora and the snowball moonlets pursued their endless, endlessly changing dance around the F Ring, and the ring’s rope of icy fragments poured around Saturn, as it had long before the distant ancestors of humanity took their first steps across the African plains, as it would long after the unknowably distant descendants of humanity had forgotten all about their first home.
(Thanks to James Alan Gardner, who suggested it.)
