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.
