TITAN, second in size among the moons of the solar system only to Jupiters
Ganymede and then by just the barest of margins, had been a constant source
of enigmas for astronomers and planetary physicists virtually since its discovery
by Christiaan Huyghens in 1655. One of the first questions to be asked was whether
it possessed an atmosphere, thus making it unique among the planetary satellites.
When that was at last resolved affirmatively in the early 1940s, other questions
arose: What did the atmosphere consist of, and what were its physical conditions
at various depths? For more than thirty years attempts at measuring the bodys
optical, infrared, and radio spectra yielded inconsistent and sometimes contradictory
results. The close flyby of the American Voyager I probe in 1980 resolved
some of the basic issues: Titans atmosphere was mostly nitrogen, with
significant proportions of argon, methane, and hydrogen, plus trace amounts
of numerous hydrocarbons and nitrogenous compounds. Surface pressure was around
1.5 times that of Earths atmosphere, which at the estimated temperature
of minus 179 degrees Celsius and with Titans surface gravity of 0.14 suggested
about ten times as much gas per unit area as one Earth. As had been suspected
by many theorists, the dense, reddish clouds blanketing the surface turned out
to be an aerosol suspension at an altitude of two hundred kilometers, consisting
of molecular fragments formed by ultraviolet dissociation of the gases in the
upper atmosphere. According to most models, the aerosol particles would gradually
recombine into heavier polymers and precipitate out of the atmosphere to form
surface deposits of considerable depth, but this hadnt been verified since
the clouds were everywhere opaque. Because of the cloud blanket and Titans
remoteness from the Sun, daylight on the surface would be about as bright, it
was estimated, as a moonlit night on Earth.
The returned data were consistent with surface conditions close to the
triple-point of the solid, liquid, and gaseous phases of methane, which raised
the intriguing possibility that methane could well exist as a gas in the lower
atmosphere and a liquid on the surface, thus playing a role similar to that
of water on Earth. Conceivably, therefore, the surface of Titan could consist
of methane oceans and water-ice continents covered by nitrogenous-hydrocarbon
soil, above which methane rain precipitated from methane clouds formed below
the aerosol blanket. It was even possible that the release of radioactive heat
in the interior might maintain reservoirs of water that could escape to the
surface as "ice lava," and perhaps provide a fluid substrate for mountain-building
and other tectonic processes. But with the diversion of funding from planetary
exploration programs to feed the ongoing insanity of the arms race, little more
was learned until the arrival of the European probe at Saturn, less than three
years before the Orion.
Radar mapping by the Dauphin orbiter had indeed revealed the existence
of vast oceans, islands, continents, and mountains below Titans all-obscuring
clouds, and details of the natural geography had been published widely. However,
as the Orions occupants had learned only after leaving Earth, the
orbiter had also sent back radar images of highly reflective objects suggestive
of artificial metallic constructions, which in many places covered huge areas
too densely to be resolved individually. All mention of that had been censored
from the published information, along with any reference to the machines glimpsed
by the Dauphins short lived surface landers and the advanced culture
that had originated them. At least, the inferred sizes of the constructions
and the areas which they covered on some parts of the surface had seemed indicative
of an advanced culture. But in almost three years the orbiters instruments
had failed to observe any activity in space around Titan, or even to detect
any sign of aircraft in the lower atmosphere; and except for intermittent transmissions
emanating from a few sources pinpointed on the surface, the radio spectrum had
been strangely silent.
No more was learned until the Orion went into orbit above Titan
and began sending reconnaissance drones down through the aerosol layer and the
lower-altitude methane clouds to scan the surface. The views sent back had been
at first perplexing, then bewildering, and finally staggering as the missions
scientists gradually unraveled what they implied. The views had shown what appeared
to be alien towns consisting of unusual buildings that resembled enormous, intricately
shaped hollow plants more than anything fabricated according to recognizable
methods, which was difficult to explain since there were also plenty of examples
of immense and elaborate engineering constructions. If the aliens had the technology
to build factories, why didnt they build cities to live in? Perhaps because
of their notions of values and aesthetics, somebody suggested.
Then had come the first indications that maybe the aliens werent
so professional at managing their technology after all. View after view showed
chaotic situations where entire industrial complexes seemed to have overflowed
their boundaries, spilling plant and machinery out across the surrounding country
with outgrowths from different centers invading each others territories
and mixing themselves up in hopeless confusion. In some areas the mess of working
and broken-down machinery, all buried amid piles of scrap and assorted parts,
stretched for miles, yet much of it managed, somehow, to continue functioning.
If the aliens engineers were capable of efficient and purposeful design at all--and
some of the designs seemed astonishingly advanced--how could they have let things
get into such a state? It made no sense.
As the drones were sent lower to obtain telescopic close-ups both in infrared
and at normal wavelengths using flares and searchlights, the scientists monitoring
the views back in the Orion had waited breathlessly for their first glimpse
of an alien. But they never found any. There were thousands of ingeniously conceived,
freely mobile machines, to be sure, some of them displaying extraordinary degrees
of versatility and behavioral adaptability, with all manner of types apparently
specialized for just about every task imaginable . . . but never once was there
a trace of the aliens whose needs all the activity was presumably intended to
serve. Some of the scientists had speculated that the aliens were too tiny to
show up on the pictures. But if so, why would they make machines that were so
much larger? It didnt add up. Maybe the aliens lived below the surface
and never came out, leaving the machines to mange everything on the surface.
Maybe they just stayed in their vegetable houses all the time. Maybe . . . but
nobody found such suggestions very satisfying.
And then, as the scientists continued to study replays form all over Titan,
they began noticing something remarkable about a particular "species"
of erect, bipedal, vaguely humanoid robot that seemed to be represented everywhere
to a greater of lesser extent: Everything they seemed to do was unremarkably
familiar. Their patterns of coming and going in and out of the houses and about
the towns, sometimes alone and sometimes in groups, stopping occasionally upon
meeting others, were the same as could be seen in communities anywhere; they
tended plantations of odd-looking growths that in some ways resembled their
peculiar organic houses; they wore what looked like clothes; they herded flocks
of mechanical "animals," and--more amazingly still-were frequently
seen to ride them; they gathered in crowds, and there was an instance of two
groups of them fighting each other; and once or twice when the drones went too
low, their reactions showed every characteristic of fear, and occasionally,
panic. In short, as far as could be ascertained from pictures, they acted exactly
as people did.
Which explained, of course, why nobody was having any luck in finding
aliens--at least, no the flesh-and-blood or whatever-and-whatever kinds of "conventional"
aliens that planetary biologists had speculated about for years.
Titan was inhabited by machines. It possessed an electro-mechanical biosphere
which included, apparently, a dominant species of culturally developed, intelligent,
and presumably self-aware robot. The scientists christened them the Taloids,
after Talos, the bronze man created by Hephaestus, the blacksmith son of Hera
and Zeus. But clearly Titan could never have evolved such a system from nothing.
So how had the machines come to be there? They had to be products of an alien
civilization that had either brought them to Titan or sent them there. When?
What for? Why Titan? Where were the aliens? Nobody had any answers. As always,
Titan had thrown up a new batch of mysteries as soon as the earlier ones were
resolved. Evidently it would be far from running low on its supply of them for
a while to come.