Read Xeelee: Endurance for Free Online Page B

rains out at the north pole. In time it will be winter here and summer there, and the cycle will reverse. Small worlds have simple climate systems, Jovik. As I’m sure a curator ought to know . . .’
    We came to the edge of the ethane lake. In that dim light it looked black like tar, and sluggish ripples crossed its surface. Patches of something more solid lay on the liquid, circular sheets almost like lilies, repellently oily. The lake stretched off black and flat to the horizon, which curved visibly, though it was blurred in the murky air.
    It was an extraordinary experience to stand there in an exosuit and to face an ocean on such an alien world, the sea black, the sky and the shore brown. And yet there was again convergence with the Earth. This was, after all, a kind of beach. Looking around I saw we were in a sort of bay, and to my right, a few kilometres away, a river of black liquid had cut a broad valley, braided like a delta, as it ran into the sea.
    And, looking that way, I saw something lying on the shore, crumpled black around a grain of paleness.
    Miriam wanted samples from the lake, especially of the plates of gunk that floated on the surface. She opened up her pack and extracted a sampling arm, a remote manipulator with a claw-like grabber. She hoisted this onto her shoulder and extended the arm, and I heard a whir of exoskeletal multipliers. As the arm plucked at the lily-like features, some of them broke up into strands, almost like jet-black seaweed, but the arm lifted large contiguous sheets of a kind of film that reminded me of the eerie wings of the Titan birds that had attacked us.
    Miriam quickly grew excited at what she was finding.
    ‘Life,’ I guessed.
    ‘You got it. Well, we knew it was here. We even have samples taken by automated probes. Though we never spotted those birds before.’ She hefted the lake stuff, films of it draped over her gloved hand, and looked at me. ‘I wonder if you understand how exotic this is. I’m pretty sure this is silane life. That is, based on a silicon chemistry, rather than carbon . . .’
    The things on the lake did indeed look like black lilies. But they were not lilies, or anything remotely related to life like my own. Life of our chemical sort is based on long molecules, with a solvent to bring components of those molecules together. Our specific sort of terrestrial life, which Miriam called ‘ CHON life’, after its essential elements carbon, hydrogen, oxygen and nitrogen, uses water as its solvent, and carbon-based molecules as its building blocks: carbon can form chains and rings, and long stable molecules like DNA .
    ‘But carbon’s not the only choice, and nor is water,’ Miriam said. ‘At terrestrial temperatures silicon bonds with oxygen to form very stable molecules.’
    ‘Silicates. Rock.’
    ‘Exactly. But at very low temperatures, silicon can form silanols, which are capable of dissolving in very cold solvents – say, in this ethane lake here. When they dissolve they fill up the lake with long molecules analogous to our organic molecules. These can then link up into polymers using silicon-silicon bonds, silanes. They have weaker bonds than carbon molecules at terrestrial temperatures, but it’s just what you need in a low-energy, low-temperature environment like this. With silanes as the basis you can dream up all sorts of complex molecules analogous to nucleic acids and proteins—’
    ‘Which is what we have here.’
    ‘Exactly. Nice complicated biomolecules for evolution to play with. They are more commonly found on the cooler, outer worlds – Neptune’s moon Triton for example. But this lake is cold enough. The energy flow will be so low that it must take a lo-ong time for anything much to grow or evolve. But on Titan there is plenty of time.’ She let the filmy stuff glide off her manipulator scoop and back into the lake. ‘There’s so much we don’t know. There has to be an ecology in there, a food chain. Maybe the