Xeelee: Endurance (5 page)

9

The days are very long on Titan, and by the time we got back to the gondola nothing seemed to have changed about the landscape or the sky – not a diffuse shadow had shifted. We found Poole and Dzik, surrounded by alien mystery, happily fixing big balloon wheels to axles slung beneath the crumpled hull. Boys will be boys.

When they were done, we all climbed back aboard. Poole had reset some of the interior lamps so they glowed green, yellow and blue; it was a relief to be immersed once more in bright Earth light.

We set off in our gondola-truck for the next part of our expedition. We were making, I was told, for an impact crater believed to hold liquid water, which itself was not far from a cryovolcano, another feature of interest for the expedition. This site was perhaps a hundred kilometres from where we had come down.

Miriam transferred her lake samples to cold stores, and ran some of them through a small onboard science package. She jabbered about what she had discovered. Poole encouraged her more than Dzik did, but even that wasn’t much. Dzik and Poole were more interested at that moment in playing with the gondola. They sat at an improvised driver’s console and fussed over gear ratios and the performance of the big tyres. Poole even insisted on driving the bus himself, though Titan was so flat and dull for the most part he could easily have left the chore to the onboard systems. That proved to me the fallacy of not bringing along specialist biologists on a jaunt like this. It was only Miriam who seemed to have a genuine passion for the life systems we were supposed to be here to study; Dzik and Poole were too easily distracted by the technology, which was, after all, only a means to an end.

They had, however, rearranged the interior to make it feel a little less cramped. The couches had been separated and set up around the cabin, so you could sit upright with a bit of elbow room. The cabin was pressurised so we could remove our helmets, and though the expandable walls didn’t work any more there was room for one at a time to shuck off his or her exosuit. Poole ordered us to do so; we had already been inside the suits for a few hours, and the suits, and ourselves, needed some down time. Poole had set up a curtained-off area where we could let our discarded suits perform their self-maintenance functions while we had showers – of water recycled from our urine and sweat, which was deemed a lot safer than melt from the ice moon. Poole himself used the shower first, and then Miriam. She was hasty, eager to get back to her work, and kept talking even while she cleaned up.

After Miriam was out of the shower I took my turn. It was a miserable drizzle and lukewarm at that, but it was a relief to let my skin drink in the water. I was quick, though; with the unknown dangers of Titan only centimetres away beyond the gondola’s fragile metal walls, I didn’t want to spend long outside the security of the suit.

It was scarcely a comfortable ride, even discounting the calculating face of Harry Poole glaring from wall-mounted slates. I was relieved when, after a couple of hours, we reached our destination.

At that point Bill Dzik was in the shower. Safely suited up, with Dzik’s offensive presence absent, I was able to sit forward in my couch and peer over Miriam’s and Poole’s shoulders at the landscape outside. That cryovolcano was a mound that pushed out of the landscape some kilometres to the west of us. It had the look of a shield volcano, like Hawaii or Mons Olympus, a flat-profiled dome with a caldera on the top. It wasn’t erupting while we sat there, but I could see how successive sheets of ‘lava’ had plated its sides. That lava was water ice, heavily laced with ammonia, which had come gushing up from this world’s strange mantle, a sea of liquid water locked under the ice, kilometres below our tyres.

As for the crater lake, I saw nothing but a plain, flatter and even more featureless than the average, covered with a thin scattering of ice sand. But the lake was there, hidden. Poole extracted radar images which showed the unmistakable profile of an impact crater, directly ahead of us, kilometres wide. Such is the vast energy pulse delivered by an infalling asteroid or comet – or, in Saturn’s system, perhaps a ring fragment or a bit of a tide-shattered moon – that the water locally can retain enough heat to remain liquid for a long time, perhaps thousands of years. Such a lake had formed here, and then frozen over with a thin crust, on top of which that skim of sand had been wind-blown. But the briny lake remained under the ice, hoarding its heat.

And, studded around the lake’s circular rim, we saw more sponge-like masses like the one we had discovered wrapped up in silane film at the shore of the polar lake. These masses were positioned quite regularly around the lake, and many were placed close by crevasses that seemed to offer a route down into the deep structure of the ice rock beneath us. Miriam started gathering data eagerly.

Meanwhile, Poole was puzzling over images returned from the very bottom of the crater lake. He had found motion, obscure forms labouring. They looked to me like machines quarrying a rock deposit. But I could not read the images well enough, and as Poole did not ask for my opinions I kept my mouth shut.

Miriam Berg was soon getting very agitated by what she was finding. Even as she gathered the data and squirted it up to Harry Poole in the
Crab
, she eagerly hypothesised. ‘Look – I think it’s obvious there are at least two kinds of life here, the silanes of the ethane lakes and the
CHON
sponges. I’ve done some hasty analysis on the
CHON
tissues. They’re like us, but not identical. They use a subtly different subset of amino acids to build their proteins; they have a variant of our
DNA
in there – a different set of bases, a different coding system. The silanes, meanwhile, are like the life systems we’ve discovered in the nitrogen pools on Triton, but again not identical, based on a different subset of silicon-oxygen molecular strings.

‘It’s possible both forms of life were brought here through panspermia – the natural wafting of life between the worlds in the form of something like spores, blasted off their parent world by impacts and driven here by sunlight and gravity. If the System’s
CHON
life arose first on Earth or Mars, it might easily have drifted here and seeded in a crater lake, and followed a different evolutionary strategy. Similarly the silanes at the poles floated here from Triton or somewhere else, found a congenial place to live, and followed their own path, independently of their cousins . . .’ She shook her head. ‘It seems remarkable that here we have a place, this moon, a junction where families of life from
different ends of the Solar System
can coexist.’

‘But there’s a problem,’ Bill Dzik called from his shower. ‘Both your silanes and your sponges live in short-term environments. The ethane lakes pretty much dry up every Titan year. And each crater lake will freeze solid after a few thousand years.’

‘Yes,’ Miriam said. ‘So both forms need to migrate. And that’s how, I think, they came to cooperate . . .’

She sketched a hasty narrative of the
CHON
sponges leaving the crater lakes as they cooled, and finding their way to the summer pole. Maybe they got there by following deep crevasses, smashed into Titan’s ice crust by the impacts that dug out crater lakes like this one in the first place. Down there they would find liquid water, kilometres deep and close to the ammonia ocean. It would be cold, briny, not to terrestrial tastes, but it would be liquid, and survivable. And at the pole they would find the silane lilies floating on their ethane seas. The lilies in turn needed to migrate to the winter pole, where their precious life-stuff ethane was raining out.

Miriam mimed, her fist touching her flattened palm. ‘So they come together, the sponges and the lilies—’

‘To make the Titan birds,’ I said.

‘That’s the idea. The timing must be complicated, but both need to migrate. The birds come flapping up out of the lake, just as we saw, heading for the winter pole: sponges as bodies or brains, silanes as wings, one seeking cold, one warmth, but both needing to be on the move. Maybe the sponges get dropped off at fresh crater lakes along the way, across the surface of the planet. It’s a true symbiosis, with two entirely different spheres of life intersecting – and cooperating, for without the migration neither form could survive alone.’ She looked at us, suddenly doubtful. ‘We’re all amateurs here. I guess any competent biologist could pick holes in that theory the size of Saturn’s rings.’

Dzik said, ‘No competent biologist would even be hypothesising this way, not with so few facts.’

‘No,’ Harry said tinnily from his slate. ‘But at least you’ve come up with a plausible model, Miriam. And all without the need to evoke even a scrap of sentience. Good job.’

‘There are still questions,’ Miriam said. ‘Maybe the sponges provide the birds’ intelligence, or at least some kind of directionality. But what about power? The lilies especially are a pretty low-energy kind of life form . . .’

Michael Poole said, ‘Maybe I can answer that; I’ve been doing some analysis of my own. I can tell you a bit more about the silane lilies’ energy source. Believe it or not – even on a world as murky as this – I think they’re photosynthesising.’ And he ran through the chemistry he thought he had identified, using entirely different compounds and molecular processing pathways from the chlorophyll-based green-plant photosynthesis of Earth life.

‘Of course,’ Miriam said. ‘I should have seen it. I never even asked myself what the lilies were
doing
while they were lying around on the lake’s surface . . . Trapping sunlight!’

Harry was growing excited too. ‘Hey, if you’re right, son, you may already have paid for the trip. Silane-based low-temp photosynthesisers would be hugely commercially valuable. Think of it, you could grow them on those nitrogen lakes on Triton, and go scudding around the outer System on living solar sails.’ His grin was wide, even in the reduced Virtual image.

Poole and Miriam were smiling too, staring at each other with a glow of connection. Theirs was a strange kind of symbiosis, like silane lily and
CHON
sponge; they seemed to need the excitement of external discovery and achievement to bring them together.

Well, there was a happy mood in that grounded gondola, the happiest since we had crashed. Even Bill Dzik as he showered was making grunting, hog-like noises of contentment.

And then there was a crunching sound, like great jaws closing on bone, and the whole bus tipped to one side.

I had my helmet over my head in a heartbeat. Poole and Miriam staggered and started shouting instructions to each other.

Then there was another crunch, a ripping sound – and a scream, a gurgling, quickly strangled, and an inward rush of cold air that I felt even through my exosuit. I turned and saw that, near the shower partition, a hole had been ripped in the side of the gondola’s flimsy hull, revealing Titan’s crimson murk. Something like a claw, or a huge version of Miriam’s manipulator arm, was working at the hull, widening the breach.

And Bill Dzik, naked, not metres from the exosuit that could have saved him, was already frozen to death.

That was enough for me. I flung open the hatch in the gondola roof and lunged out, not waiting for Miriam or Poole. I hit the Titan sand and ran as best I could. I could hear crunching and chewing behind me. I did not look back.

When I had gone a hundred metres I stopped, winded, and turned. Poole and Miriam were following me. I was relieved that at least I was not stranded on Titan alone.

And I saw what was becoming of our gondola. The machines that had assailed it – and they were machines, I had no doubt of it – were like spiders of ice, with lenticular bodies perhaps ten metres long, each equipped with three grabber claws attached to delicate low-gravity limbs. Four, five of these things were labouring at the wreck of our gondola. I saw that they had gone for the wheels first, which was why we had tipped over, and now were making a fast job of ripping the structure apart. Not only that, beyond them I saw a line of similar-looking beasts carrying off silvery fragments – they could only be pieces of the gondola – and hauling them up the rising ground towards the summit of the cryovolcano. Some of the larger components of the wreck they left intact, such as the GUTengine module, but they carried them away just as determinedly.

In minutes, I saw, there would be little left of our gondola on the ice surface – not much aside from Bill Dzik, who, naked, sprawled and staring with frozen eyeballs, made an ugly corpse, but had not deserved the fate that had befallen him.

Harry Poole’s head popped into Virtual existence before us. ‘Well,’ he said, ‘that complicates things.’

Michael swatted at him, dispersing pixels like flies.

10

‘Dzik is dead,’ I said. ‘And so are we.’ I turned on Michael Poole, fists bunched in the thick gloves. ‘You and your absurd ambition – it was always going to kill you one day, and now it’s killed us all.’

Michael Poole snorted his contempt. ‘And I wish I’d just thrown you into a jail back on Earth and left you to rot.’

‘Oh, Lethe,’ Miriam said with disgust. She was sifting through the scattered debris the spiders had left behind. ‘Do you two have any idea how ridiculous you look in those suits? Like two soft toys squaring up for a fight. Anyhow, you aren’t dead yet, Jovik.’ She picked up bits of rubbish, rope, a few instruments, some of her precious sample flasks, enigmatic egg-shaped devices small enough to fit in her fist – and food packs.

Michael Poole’s curiosity snagged him. ‘They didn’t take everything.’

‘Evidently not. In fact, as you’d have noticed if you weren’t too busy trading insults with your passenger, they didn’t take
us
. Or Bill.’

‘What, then?’

‘Metal. I think. Anything that has a significant metal component is being hauled away.’

‘Ah.’ Poole watched the spiders toiling up their volcano, bits of our ship clutched in their huge claws. ‘That makes a sort of sense. One thing this moon is short of is metal. Has been since its formation. Even the core is mostly light silicate rock, more like Earth’s mantle than its iron core. Which maybe explains why every surface probe to Titan across seventeen hundred years has disappeared without a trace – even the traces of your illegal sample collectors, Emry. They were taken for the metal.’

I felt embarrassed to contribute to this dry discussion, but I referred to the blocky shapes I had seen toiling on the lake floor, in the radar images of the deeps. ‘As if they were quarrying? Maybe they were relatives of these spiders, after the metallic content of the meteorite that dug out the crater in the first place.’

Poole pursed his lips, clearly trying not to look impressed. ‘Sounds a good guess. The metal in a fair-sized space rock could take centuries to extract.’

‘Well, in any event, they left useful stuff behind,’ said Miriam, picking through the debris. ‘Anything ceramic, glass fibre, plastic. And the food packs. I’ll show you how to interface them to your suit’s systems, Emry, you can get at the food without opening up your helmet . . . We won’t starve, at least.’

Poole, you see, had homed in on theory, while Miriam focused on the essentials that might keep us alive. That tells you everything about the man’s lofty nature, and its flaws.

‘But they took the GUTengine, didn’t they?’ I put in sharply. ‘Our power source. Without which we’ll soon freeze to death, no matter how well fed we are.’

‘And, incidentally,’ Miriam said, ‘the identity-backup deck. We cached the backups in the GUTengine’s own control and processing unit, the most reliable store on the gondola. If we lose that, we lose the last trace of poor Bill too.’

I couldn’t help but glance at Dzik’s corpse, fast-frozen on the ice of Titan.

Not Poole, though. He was watching those receding spiders. ‘They’re heading down into the volcano. Which is a vent that leads down into the mantle, the ammonia sea, right? Why? What the hell
are
those things?’

Miriam said, ‘One way to find out.’ She hefted one of those ceramic eggs in her right hand, pressed a stud that made it glow red, and hurled it towards the nearest spider. It followed a low-gravity arc, slowing quickly in the thick air, and it seemed to take an age to fall. But her aim was good, and it landed not a metre from the spider.

And exploded. Evidently it had been a grenade. The spider shattered satisfactorily, those ugly claws going wheeling through the air.

Miriam had already started to run towards the spider. ‘Come on.’ You couldn’t fault her directness.

Poole followed, and I too, unwilling to be left alone with Bill’s frozen remains. Poole called, ‘What did you do that for?’

‘We want to know what we’re dealing with, don’t we?’

‘And why are we running?’

‘So we can get there before the other spiders get rid of the corpse.’

And sure enough the other spiders, still laden with bits of the gondola, had already turned, and were closing on their shattered fellow. They didn’t seem perturbed by the sudden destruction of one of their kind, or of our approaching presence.

We got there first, and we squatted around the downed spider in a splash of suit light. The spider hadn’t broken open; it was not enclosed by a hull or external carapace. Instead it had shattered into pieces, like a smashed sculpture. We pawed at the debris chunks, Miriam and Poole talking fast, analysing, speculating. The chunks appeared to be mostly water ice, though Poole speculated it was a particular high-pressure form. The internal structure was not simple; it reminded me of a honeycomb, sharp-edged chambers whose walls enclosed smaller clusters of chambers and voids, on down through the length scales like a fractal. Poole pointed out threads of silver and a coppery colour – the shades were uncertain in Titan’s light. They were clearly metallic.

The other spiders closed in on the corpse. Wary of getting chomped by accident we backed off, dimming our suit lights.

Miriam asked, ‘So, biological or artificial? What do you think?’

Poole shrugged. ‘They seem dedicated to a single purpose, and have metallic components. That suggests artificial. But that body interior looks organic. Grown.’

I felt like putting Poole in his place. ‘Maybe these creatures transcend your simple-minded categories. Perhaps they are the result of a million years of machine evolution. Or the result of a long symbiosis between animal and technology.’

Poole shook his head. ‘My money’s on biology. Given enough time, necessity and selection can achieve remarkable things.’

Miriam said, ‘But why would their systems incorporate metal if it’s so rare here?’

‘Maybe they’re not native to Titan,’ I said. ‘Maybe they didn’t evolve here.’ But they weren’t listening to me. And besides, they didn’t want to hear any kind of theory that implied sentience. ‘The real question is,’ I said more urgently, ‘what do we do now?’

The head of Harry Poole, projected somehow by our suit’s comms systems, once more popped into existence, the size of an orange, floating in the air. The small scale made his skin look even more unnaturally smooth. ‘And that,’ he said, ‘is the first intelligent question you’ve asked since we press-ganged you, Jovik. You ready to talk to me now?’

Michael Poole glared at his father, then turned and sucked water from the spigot inside his helmet. ‘Tell us how bad it is, Harry.’

‘I can’t retrieve you for seven days,’ Harry said.

I felt colder than Titan. ‘But the suits—’

‘Without recharge our suits will expire in three days,’ Poole said. ‘Four at the most.’

I could think of nothing to say.

Harry looked around at us, his disembodied head spinning eerily. ‘There are options.’

‘Go on,’ Poole said.

‘You could immerse yourselves in the crater lake. The suits could withstand that. It’s cold in there, the briny stuff is well below freezing, but it’s not as cold as the open air. Kept warm by the residual heat of impact, remember. Even so you would only stretch out your time by a day or two.’

‘Not enough,’ Miriam said. ‘And we wouldn’t get any work done, floating around in the dark in a lake.’

I laughed at her. ‘Work? Who cares about work now?’

Poole said, ‘What else, Harry?’

‘I considered options where two people might survive, rather than three. Or one. By sharing suits.’

The tension between us rose immediately.

Harry said, ‘Of course those spiders also left you Bill’s suit. The trouble is the power store is built into the fabric of each suit. To benefit you’d have to swap suits. I can’t think of any way you could do that without the shelter of the gondola; you’d freeze to death in a second.’

‘So it’s not an option,’ Poole said.

Miriam looked at us both steadily. ‘It never was.’

I wasn’t sure if I was relieved or not, for I had been determined, in those few moments when it seemed a possibility, that the last survivor in the last suit would be myself.

‘So,’ Poole said to Harry, ‘what else?’

‘You need the gondola’s GUTengine to recharge your suits,’ Harry said. ‘There’s just no alternative.’

I pointed at the toiling spiders on the cryovolcano. ‘Those beasts have already thrown it into that caldera.’

‘Then you’ll have to go after it,’ Harry said, and, comfortably tucked up in the
Crab
, he grinned at me. ‘Won’t you?’

‘How?’ I was genuinely bewildered. ‘Are we going to build a submarine?’

‘You won’t need one,’ Harry said. ‘You have your suits. Just jump in . . .’

‘Are you insane? You want us to jump into the caldera of a volcano, after a bunch of metal-chewing monster spiders?’

But Miriam and Poole, as was their way, had pounced on the new idea. Miriam said, ‘Jovik, you keep forgetting you’re not on Earth. That “volcano” is just spewing water, lava that’s colder than your own bloodstream.’ She glanced at Harry. ‘The water’s very ammonia-rich, however. I take it our suits can stand it?’

‘They’re designed for contact with the mantle material,’ Harry said. ‘We always knew that was likely. The pressure shouldn’t be a problem either.’

Poole said, ‘As for the spiders, they will surely leave us alone if we keep away from them. We know that. We might even use them in the descent. Follow the spiders, find the engine. Right?’

Harry said, ‘And there’s science to be done.’ He displayed data in gleaming Virtual displays – cold summaries only metres away from Bill Dzik’s corpse. Harry said that his preliminary analysis of our results showed that the primary source of the atmosphere’s crucial methane was not in the surface features, but a venting from the cryovolcanoes. ‘And therefore the ultimate source is somewhere in the ammonia sea,’ Harry said. ‘Biological, geological, whatever – it’s down there.’

‘
OK
,’ Poole said. ‘So we’re not going to complete the picture unless we go take a look.’

‘You won’t be out of touch. I’ll be able to track you, and talk to you all the way in. Our comms link have a neutrino-transmission basis; a few kilometres of ice or water isn’t going to make any difference to that.’

A few
kilometres
? I didn’t like the sound of that.

‘So that’s that,’ Miriam said. ‘We have a plan.’

‘We have a shared delusion,’ I said.

They ignored me. Poole said, ‘I suggest we take an hour out. We can afford that. We should try to rest; we’ve been through a lot. And we need to sort through these supplies, figure out what we can use.’

‘Yeah,’ said Miriam. ‘For instance, how about nets of ice as ballast?’

So he and Miriam got down to work, sorting through the junk discarded by the spiders, knotting together cables to make nets. They were never happier than when busy on some task together.

And there was Bill Dzik, lying on his back, stark naked, frozen eyes staring into the murky sky. I think it tells you a lot about Michael Poole and even Miriam that they were so focused on their latest goal that they had no time to consider the remains of this man with whom they had worked, apparently, for decades. Well, I had despised the man, and he had despised me, but something in me cringed at the thought of leaving him like that.

I looked around for something I could use as a shovel. I found a strut and a ceramic panel from some internal partition in the gondola, and used cable to join them together. Then I dug into the soil of Titan. The blade went in easily; the icy sand grains didn’t cling together. As a native of Earth’s higher gravity I was over-powered for Titan, and lifted great shovelfuls easily. But a half-metre or so down I found the sand was tighter packed and harder to penetrate, no doubt some artefact of Titan’s complicated geology. I couldn’t dig a grave deep enough for a man the size of Bill Dzik. So I contented myself with laying him in my shallow ditch, and building a mound over him. Before I covered his face I tried to close his eyes, but of course the lids were frozen in place.

All the time I was working I clung to my anger at Michael Poole, for it was better than the fear.