He'd forced only a little of his own nature onto Paolo—like any good bridger, just enough to let the two of them understand each other—and he'd gladly see subsequent generations embrace all the possibilities of software existence. But redesigning himself in an attempt to do the same in person would have been nothing but self-mutilation. That was why he dreamt the old way: confused, unconvincing, uncontrollable dreams, not the lucid, detailed, wish-fulfillment fantasies or cloyingly therapeutic psychodramas of the assimilated. His faithfully mammalian dreams would never bring Liana back; nor would they drag him down some tortuous path of allegory and catharsis designed to reconcile him to her loss. They revealed nothing, meant nothing, changed nothing. But to excise or disfigure them would have been like taking a knife to his flesh.
Voltaire lay low in the sky, in the direction Orlando thought of as east. It was a dim reddish speck at this distance, about as bright as Mercury seen from Earth, an ancient K5 star only one sixth as luminous as the sun. Five terrestrial planets, and five gas giants more in Neptune's league than Jupiter's, had been observed or inferred long before the Diaspora's launch, but individual spectra for the inner planets had continued to elude both the colossal instruments back home and the extremely modest equipment carried by the polis itself.
"What are you offering? Sanctuary?" He gazed at the star. Not likely. Just a few more barren planets. A few more lessons in the fragility of life, and the indifference of the forces that created and destroyed it.
Back in the cabin, Orlando considered ignoring the call and going straight hack to sleep. It would either be bad news—another Fomalhaut, or worse, or evidence of life so subtle that it had taken a century or two of exploration to uncover. Maybe one of the moons of one of the gas giants orbiting 51 Pegasus had yielded a few fossilized microbes in some previously uncharted crevice. Evidence of a third biosphere would be hugely significant, but he was tired of poring over the details of distant worlds in the pre-dawn darkness.
Then again, maybe the Orphean squid had finally gained an inkling of the nature of their floating universes. Orlando laughed wearily. He was jealous, but he was hooked; the chance of a development in squid culture was enough to puncture his indifference.
He clapped his hands, and the cabin fit up. He sat on his bed and addressed the wall screen. "Report." Text appeared, summarizing his exoself's reasons for waking him. Orlando could not abide non-sentient software that talked back.
The news was local, though the chain of events behind it had started hack on Earth. Someone in Earth C-Z had designed an improved miniature spectroscope, which could he constructed by nanoware modifications to the existing polis-borne model. The local astronomy software had taken it upon itself to do just that, and thanks to the new instrument the atmospheric chemistry of Voltaire's ten planets had now been determined.
The first surprise was that the innermost planet, Swift, possessed an atmosphere rather different than expected: mostly carbon dioxide and nitrogen, at a fifth the total pressure of Earth's, but there were also significant traces of hydrogen sulphide and water vapor. With only 60 percent of Earth's gravity, and a surface temperature averaging 70 degrees Celsius, virtually all of Swift's water should have been lost in the twelve billion years since its formation—broken down by UV into hydrogen and oxygen, with the hydrogen escaping into space.
The second surprise was that the hydrogen sulphide appeared not to be in thermodynamic equilibrium with the rest of the atmosphere. It was either being outgassed from the planet's interior—unlikely, after twelve billion years—or it was a by-product of some form of non-equilibrium chemical process driven by the light from Voltaire. Quite possibly life.
But the third surprise set Orlando's skin tingling, outweighing any drab visions of boiling lakes full of malodorous bacteria. The spectra also showed that the molecules in Swift's atmosphere contained no ordinary hydrogen, no carbon-12, no nitrogen-14, no oxygen-16, no sulfur-32. Not a trace of the most cosmically abundant isotopes, though they were present in the normal proportions on Voltaire's nine other planets. On Swift, there was only deuterium, carbon-13, nitrogen-15, oxygen-18, sulfur-34: the heaviest stable isotope of each element.
That explained why water vapor was still present, these heavier molecules would stay closer to the surface of the planet, and when they were split the deuterium would have more of a chance to stick around and recombine. But not even the preferential loss of lighter isotopes could explain these impossibly skewed abundances; Swift's atmosphere contained hundreds of thousands of times more deuterium than it should have possessed when the planet was formed. The software was noncommittal about the implications, but Orlando had no doubt. Someone had transmuted these elements. Someone had deliberately weighed down this planet's atmosphere, in order to prolong its life.
13
SWIFT
Carter-Zimmerman polis, Swift orbit
85 801 536 954 849 CST
16 March 4953, 15:29:12.003 UT
Yatima rode the probe beside Orlando's, seeing both as sleek, finned cars about three delta long, hovering above Swift's flat red desert. The real probes were spheres half a millimeter wide, powered by the light of Voltaire, largely borne up by the wind but occasionally generating lift by spinning, moving forward by pumping atmospheric gases through a network of channels coated with molecular cilia. Even with elaborate piloting software, turning the car's steering wheel didn't always have the desired effect.
"Oasis."
Orlando looked around. "Where?"
"On your left." Yatima hadn't turned yet, not wanting to sideswipe Orlando. It was unlikely that the probes themselves would touch, and it would hardly matter it they did, but one of the first things ve'd done after arriving from Konishi was hardwire a strong aversion to collisions into vis navigators. People in Carter-Zimmerman did not take kindly to other people trying to occupy the same portion of a scape.
Orlando swung his car around, and they headed for the oasis. It was a puddle of water a few meters wide—tens of kilodelta, at their current scale—trapped beneath a polymer membrane. Surface tension gently stretched the membrane into a convex mirror, reflecting an expanse of pale crimson sky that seemed to hover a few centimeters below the ground. Pure water boiled at around 60 degrees in Swift's thin atmosphere, so rain could only fall on the night side, but when enough run-off gathered on a patch of spores, the whole dessicated micro-ecology came back to life, and fought to hold on to the water for as long as possible. The membrane limited evaporation, and a mixture of other chemicals raised the boiling point by up to ten degrees, but by mid-afternoon of a 507-hour day only a fraction of the oases formed overnight remained. Still, Swift life could cope with being boiled dry at least as comfortably as most primitive Earth life could cope with being frozen.
Close up, they could see through the partially reflective surface into the dazzling world below. Broad helical carnivorous weeds shone in gold and turquoise; one swarm of mites avoiding their poisoned fronds were a deep, rich red, another were (pre-Lacerta Earth) sky blue. All Swift life made heavy use of sulfur chemistry; carbon dominated, but some primordial accident seemed to have pushed sulfur into sharing the structural role, and the intensity of the colors was one side effect.