«This is still our best bet, then,» Parantham said.
«Assuming we're even in the right system,» Rakesh added.
«I wouldn't give up on that yet. If nothing obvious comes from the mapping sweep, we'll have to think about looking for microfossils.»
«Yes.» Rakesh's spirit sank; the promise was getting heavier by the hour. Here they were in the galaxy's vibrant core, and Parantham was talking about scouring a planet's worth of rocks for cavities that might once have been microbes. Still, if that was it — if this world was a bacterial graveyard, and the Aloof had invited them here merely to pay their last respects — once he'd done his duty they might yet reward him with the chance to see something more.
He toyed with an image of the four planetary orbits. No two of the ellipses shared the same plane, and the planets' axes were all over the place. That was what came of living in such crowded conditions: a neighboring star must have passed by and wreaked gravitational havoc. Rakesh ran dynamical models, testing the stability of the present arrangement, trying to get a sense of how long it might have persisted. The outer two gas giants were slowly nudging each other's orbits into a resonant configuration in which one world would complete exactly three trips around the sun to the other's two, but the process hadn't yet reached that stable endpoint. This and other signs that the system was still settling down after a profound disturbance suggested that the event had taken place between one and two hundred million years before. The same encounter might well have altered conditions on the world below them, though the geology still offered no indication that there had ever been running water.
«Metal!» Parantham announced.
«What?»
She pointed to the console. «The mapping probe just saw a glint of unoxidised, elemental metal. Mostly iron, with a number of impurities.»
Rakesh reviewed the data. High on a plateau in the tallest of the planet's mountain ranges, a metallic patch a few square meters in area had registered on radar, along with other wavelengths. Its detailed structure had not been resolved, but its chemical state alone was significant. In theory, rare geological processes could be responsible for such a deposit, but the surrounding rocks bore no witness to the necessary conditions.
They let the mapping probe continue its sweep of the planet, so as not to miss any further surprises, but they had the workshop build and launch a second probe tailored to investigate the strange glint more closely.
Rakesh said, «There was nothing in the structure or genome of the microbes we saw in the meteor that suggested they could metabolize metallic ores.»
«Viva diversity,» Parantham replied. «A microbial world is still a whole ecosystem. If this
is
biological, who knows what other niches there are that we haven't yet spotted?»
The second probe swept low over the plateau, and sent back high resolution images. The metal formed a blotchy but weirdly symmetrical patina on the rock, concentrated in six roughly elliptical lobes arranged in pairs around a central axis. It was hard to see how any underlying ore body that might have been metallized by microbes could have taken such a shape, though perhaps microbial colonies could self-organize into this pattern for some other reason. Spectroscopy revealed no organic matter, but that didn't rule anything out; a similarly remote view of the Aloof's DNA-infested meteor would have portrayed it as equally sterile.
They waited two full planetary days before taking the next step, allowing the mapping probe to image the entire surface. They passed the time arguing about the possibilities, cooking, eating, occasionally sleeping. Rakesh felt a strange mixture of urgent curiosity and an equally strong desire to prolong the unfolding process of discovery. Was this how it had been, to live in the Age of Exploration? Every world had held surprises then, when the ancestors of the Amalgam had still been slowly reaching out to find each other. Back in the disk, every planet he'd set foot upon had been visited by a hundred billion people before him, its every feature catalogued in more detail than he could hope to match with firsthand observations in a thousand years.
The mapping probe found no more elemental metal, and no other chemical anomalies at all. To the limits of the probe's resolution and sensitivity, every other structure and substance on the planet's surface could be accounted for by geological effects.
Rakesh knew exactly what he wanted to do next, but he was unsure where his obligations lay. «What are the rules about landing on a world like this? Just because we can't find a trace of life doesn't mean there aren't a billion software citizens buried in a processor somewhere.» The disk contained thousands of planets where all evidence of biological ancestry had been carefully wiped from the surface, out of a desire to avoid attracting attention. They were all catalogued now, and their inhabitants left in peace, but the earliest of the explorers who'd chanced upon such places had sometimes triggered substantial animosity.
«If the Aloof don't want us setting foot here, I'm sure they'll intervene,» Parantham replied. «If this planet has custodians who are distinct from our hosts, it's the people who brought us here who have a duty to ensure that we cause no offense. As long as we act in good faith, it's their responsibility.»
«I can't argue with that,» Rakesh conceded, «but it still doesn't feel right. Act at will and then see if you're restrained or rebuked, like a child?»
Parantham said, «They chose their relationship with us. If they want to open up a dialogue, if they want to educate us, they can do that any time. Until then, what choice do we have? We can't intuit every cultural sensitivity from first principles. So long as we do no harm, if we blunder in where we're not wanted it's up to someone with local knowledge to give us a civics lesson.»
«If you go back far enough in history,» Rakesh countered, «I can think of some civics lessons I'd rather not have.»
They argued for hours, but finally settled on a compromise. They would send down a small collection of probes to investigate the anomalous metal. They would not literally set foot on the surface, but telepresence would still grant them most of the same advantages.
Rakesh switched his senses to his avatar as it plummeted through the stratosphere, curled up inside the heat shield that protected the whole exploratory package. There was no light source within the ceramic cocoon, but when he shifted his vision to infrared the differential heating of the shield provided enough contrast for him to make out his immediate surroundings. Parantham's avatar was coiled snugly behind the laboratory/rover, his jelly-baby twin. Both of them were about a millimeter tall, and shorn of unnecessary extras, leaving torsos, pudgy arms and legs, and heads without mouths or noses. The lab's machinery would do all the smelling, and their real bodies could do all the talking.
Rakesh felt the jolt of the chute unfurling, followed by a persistent deceleration. The heat shield slowly dimmed and his weight diminished as the package drifted down into the troposphere. There was some gentle buffeting, but the descent was uneventful, with nothing to presage the sudden thud of landfall. The plateau was some ten kilometers above the average surface elevation, not quite the highest point on the planet, but close.
The shield split open. A whirring sound followed as the chute was reeled back in. Rakesh restored his vision to the usual wavelengths and looked out across the surrounding terrain, a heavily corrugated igneous landscape. It conjured up fanciful images of boiling lava frozen into glassy black rock, sandblasted for an aeon but still not rendered flat. They were about a meter from the edge of the metallic patch. Had he been his normal size, the ground here would have looked merely dimpled.
Parantham's avatar rose to its feet, and he joined her. The rover purred and advanced beside them on its flexible treads. Rakesh doubted that their diminished stature would cut much ice if there were locals watching from hidden strongholds who held some strange reverence for this site; treading lightly or not, trespass was trespass. Still, at least if these avatars were crushed out of existence their bodies on
Lahl's Promise
would stand a chance. The last backup Rakesh had made for himself was on Massa, and he had no idea what, if anything, the Aloof were retaining of their guests as insurance against misadventure.
They tramped across the undulating lava field. According to the rover, the black rock beneath them contained almost no iron, and there was no obvious cavity marking out a distinct body of ferrous ore that the putative microbes might have mined. The layer of dirty metal ahead of them looked as if it had been sprayed on to the surface.
They reached the diffuse edge of one of the six lobes. The iron was stained green and brown, presenting no silvery sheen, but it still looked more like a layer that had been deposited on top of the igneous rock than something created by converting a pre-existing source
in situ
. Models of the planet's surface evolution lent no weight to the idea that this elevated place had once been the bottom of a mineral-bearing sea, though they couldn't entirely rule out six small, iron-rich puddles at the edge of a muddy alpine lake.
The rover probed the layer across the spectrum, then sent an invisible wave of nanomachines forward to gather more information and sharpen its tentative spectroscopic estimates.
Parantham displayed the evolving isotope data in a shared visualization in front of them. «This has been refined by smelting three or four different ores from different sources,» she said. «It's not geological in origin, and it's not biogenic. Iron, nickel, chromium. it's an artificial alloy. This is
steel
. Designed to resist corrosion.»
«Can we date the smelting?» Rakesh wondered. «Aha!» There were minute traces of radioisotopes. The models suggested that the metal had been refined between one hundred and twenty and one hundred and eighty million years ago.
Rakesh's thoughts hovered between astonishment and bemusement. Had the cousins just become a great deal smarter, or was he staring at a mirage? They had yet to find a single biological molecule here. Could life have flourished on this desolate planet, to the point of giving rise to a steel-making culture, and then shrunk back down to nothing, leaving this single, shriveled artefact as its only witness?
The nanomachines advanced, probing the composition of the deposit in all directions. It was not homogeneous. Time had blurred what might have once been sharp distinctions, but hints of structure survived as complex veins of impurities threading the six lobes.
Parantham said, «What was it? A sculpture of an insect?»
Rakesh glanced away from his avatar's vision to a virtual schematic, a map of the impurities overlaid on an aerial view of the site. «It's a robot,» he declared. «A six-legged robot.»
«Perhaps.» Parantham was pondering the isotope analysis again. She said, «There are markers in this metal that fit the meteor data far better than anything else on this planet.» She hesitated. «It's a
probe
, Rakesh. From the meteor's world. This planet isn't the parent world, but the parent world sent this probe.»
Rakesh tried unsuccessfully to pull his jelly-baby face into a scowl of disbelief, but then everything fell into place.
The cousins had made steel, and mastered interplanetary flight. They had sent this six-legged robot to explore their barren sister world, more than a hundred and twenty million years ago. Out in the disk, a species with a head start like that might have circumnavigated the galaxy before Rakesh's ancestors had touched a stone tool, and built a civilization to rival the Amalgam before humans had sent a single spore to a neighboring star.
This wasn't the disk, though. Grand histories, here, were prone to truncation. A neighboring star had come too close, and either captured the planet or ejected it into interstellar space.
Rakesh said, «The meteor is about fifty million years old. The interloper passed through this system perhaps a hundred million years before then. That's why the meteor's path didn't match its chemistry; the whole planet had been traveling away from its home star for a hundred million years before the meteor was blasted off it.»
«Yet the meteor still bore life,» Parantham said. «That DNA was the same age as the meteor itself, not a remnant from an earlier epoch. Whatever the parent world endured for those hundred million years, it wasn't enough to sterilize it.»
Rakesh looked out across the stained patina of metal. «Microbes survived. But what about the probe builders?» It seemed too cruel a coincidence to believe that the interloper had come along just as they were developing the technology that might have allowed them to survive the encounter. Perhaps that had even been a trigger; perhaps they had been locked in some kind of cultural stasis until their astronomers realized that their world was in peril.
«We'll scour the system,» Parantham declared. «There might be some more clues here, they might have left something on one of the gas giants' moons.»
Rakesh agreed. «And then we go after them.» They would follow the meteor back to its source, and retrace the path of these unlucky exiles, deep into the crowded heart of the bulge.
10
As Roi launched herself across the Null Chamber, it struck her that she had never seen the place so alive with activity. She counted seven distinct groups, each numbering six people or more, gathered together on the walls and along the web, making measurements, adjusting machinery, talking excitedly, testing ideas.
She and Zak had scoured the Splinter from garm to sard in their hunt for recruits, braving libraries and workshops, abattoirs and storage depots, risking ambush every step of the way. Now the hard times were over; they had built their team, and its numbers bolstered their loyalty in a way that mere reason never could.
Near the Null Line, Ruz and his apprentices were working on their new clock, tinkering with the mechanism as they calibrated it against a cycling pair of shomal-junub stones. Zak had set them a wildly ambitious target: to create something small enough for a traveler to carry anywhere in the Splinter, oblivious to the varying weights and accurate enough to be trusted for thirty-six shifts without recalibration. After trying out many unwieldy designs, they had devised a system in which two spiral coils of metal ribbon were joined at their centers to small shafts. The first and larger of the coils was tightened by turning its shaft with a lever, and then the force as it unwound was eked out slowly and employed to feed a gentle, to-and-fro rocking of the other coil's shaft. Rendering this complex mechanism perfectly regular was a serious challenge, but the team never seemed to be short of new ideas to try, and each refinement so far had improved on the last.