Xeelee: Endurance (6 page)

11

So we climbed the flank of the cryovolcano, paralleling the trail followed by the ice spiders, who continued to toil up the slope hauling the last useful fragments of our gondola. We were laden too with our improvised gear – rope cradles, bags of ice-rock chunks for ballast, food packs. Miriam even wore a pack containing the pick of her precious science samples.

It wasn’t a difficult hike. When we had risen above the sand drifts we walked on bare rock-ice, a rough surface that gave good footing under the ridges of our boots. I had imagined we’d slip walking up a slope of ice, but at such temperatures the ice under your feet won’t melt through the pressure of your weight, as on Earth, and it’s that slick of meltwater that eliminates the friction. It was as if we climbed a surface of rough rock.

But despite the easy climb, as we neared the caldera my legs felt heavy. I had no choice but to go on, to walk into ever greater danger, as I’d had no real choice since being press-ganged in the first place.

At last we stood at the lip of the caldera. We looked down over a crudely carved bowl perhaps half a kilometre across, water-ice rock laced with some brownish organic muck. Most of the bowl’s floor was solid – evidently the cryovolcano was all but dormant – but there was a wide crevasse down which the spiders slid into darkness, one after another.

If you listened carefully you could hear a crunching sound, from deep within the crevasse. This crack in the world was what we were going to descend into.

‘Don’t even think about it,’ Miriam murmured to me. ‘Just do it.’

But first we needed a tame spider.

We climbed a few paces down the flank, and stood alongside the toiling line of spiders. Miriam actually tried to lasso one of the creatures as it crawled past us. This was a bit overambitious, as the thick air and low gravity gave her length of cable a life of its own. So she and Poole worked out another way. With a bit of dexterity they managed to snag cable loops around a few of a spider’s limbs, and Poole threw cable back and forth under the beast’s belly and over its back and tied it off, to make a kind of loose net around the spider’s body. The spider didn’t even notice these activities, it seemed, but continued its steady plod.

‘That will do,’ Poole said. ‘All aboard!’ Grasping his own burden of pack and ballast nets he made a slow-motion leap, grabbed the improvised netting, and set himself on the back of the spider. Miriam and I hurried to follow him.

So there we were, the three of us sitting on the back of the beast! ‘On any other day,’ I ventured, ‘this would seem strange.’ That won me a laugh from Miriam.

The first few minutes of the ride weren’t so bad, though the spider’s motion was jolting and ungainly, we had to cling to our cables, and we always had the unpleasant awareness that there was no conscious mind directing this beast to which we were strapped.

Then the lip of the caldera came on us, remarkably quickly. I wrapped my hands and arms tighter in the netting.

‘Here we go!’ Michael Poole cried, and he actually whooped as the spider tipped head first over the lip of the crevasse
–
and began to climb down a vertical wall. I could not see how it was clinging to the sheer surface – perhaps with suckers, or perhaps its delicate limbs found footholds. But my concern was for myself, for as the spider tipped forward we three fell head over heels, clinging to the net, a slow low-gravity fall that ended with us all hanging upside down.

‘Climb up!’ Poole called. ‘It will be easier if we can settle near the back end.’

It was good advice but easier said than done, for to climb I had to loosen my grip on the cable to which I was clinging. I was the last to reach the arse end of the descending spider, and find a bit of respite in a surface I could lie on.

And all the while the dark of the chasm closed around us, and that dreadful crunching, chewing noise from below grew louder. I looked up to see the opening of this chimney as a ragged gash of crimson-brown, the only natural light; it barely cast a glow on the toiling body of the spider. Impulsively I ordered my suit to turn on its lights, and we were flooded with glare.

Poole asked, ‘Everybody
OK
?’

‘Winded,’ Miriam said. ‘And I’m glad I took my claustrophobia pills before getting into the gondola. Look below. What’s that?’

We all peered down. It was a slab of ice that appeared to span the crevasse. For an instant I wondered if this was as deep as we would have to go to find our GUTengine. But there was no sign of toiling spiders here, or of the pieces of our gondola, and I feared I knew what was coming next. That sound of crunching grew louder and louder, with a rhythm of its own.

‘Brace yourselves,’ Poole said. Pointless advice.

Our spider hit the ice floor. It turned out to be a thin crust, easily broken – that was the crunching we had heard, as spider after spider smashed through this interface. Beyond the broken crust I caught one glimpse of black, frothy water, before I was dragged down into it, head first. For the ice was the frozen surface of a subterranean ocean.

Immersed, I was no colder, but I could feel a sticky thickness all around me, as if I had been dropped into a vat of syrup. My suit lamps picked out enigmatic flecks and threads that filled the fluid surrounding me. When I looked back, I saw the roof of this vent already freezing over, before it was broken by the plunging form of another spider, following ours.

Michael Poole was laughing. ‘Dunked in molten lava, Titan style. What a ride!’

I moaned, ‘How much longer? How deep will we go?’

‘As deep as we need to. Have patience. But you should cut your lights, Emry. Save your power for heating.’

‘No, wait.’ Miriam was pointing at the ice wall that swept past us. ‘Look there. And there!’

And I made out tubular forms, maybe half a metre long or less, that clung to the walls, or, it seemed, made their purposeful way across it. It was difficult to see any detail, for these visions quickly shot up and out of our field of view.

‘Life?’ Poole asked, boyishly excited once more.

Miriam said, ‘It looks like it, doesn’t it?’ Without warning, she loosened one hand from the net, grabbed at one of the tubes and dragged it away from its hold on the wall. It wriggled in her hand, pale and sightless, a fat worm; its front end, open like a mouth, was torn.

‘Ugh,’ I said. ‘Throw it back!’

But Miriam was cradling the thing. ‘Oh, I’m sorry. I hurt you, didn’t I?’

Poole bent over it. ‘Alive, then.’

‘Oh, yes. And if it’s surviving in this ammonia lava, I wouldn’t mind betting it’s a cousin of whatever’s down below in the sea. More life, Michael!’

‘Look, I think it’s been browsing on the ice. They are clustered pretty thickly over the walls.’

And when I looked, I saw he was right; there the tube-fish were, nibbling away, working their way slowly up the vent.

Poole speculated, ‘Maybe they actively keep the vent open?’ He took a small science box from Miriam’s pack, and there, together – even as we rode that alien’s back down into the throat of the volcano – they briskly analysed the beast’s metabolism, and the contents of the water we were immersed in, and sent the results back to the
Hermit Crab.
Even Harry’s Virtual head popped up before us, grinning inanely, in that extreme situation.

I had seen enough. With a snap, I made my suit turn its lights off. I had no desire to sit shivering in the dark as invisible ice walls plummeted past me. But I was gambling that curiosity would get the better of Poole and Miriam, and I was right; soon it was Poole whose suit glowed, spending his own precious power to light me up, as they laboured over their pointless science.

At length they came to some conclusion. ‘So I was right,’ Miriam breathed at last. ‘This vent, and the mantle ocean, host a whole other domain –
a third
on Titan, in addition to the silanes and the
CHON
sponges. Ammono life . . .’

The moon’s liquid mantle is thought to be a relic of its formation, in a part of the solar nebula where ammonia was common.

Titan was born with a rocky core and a deep ocean, of water laced with ammonia. The ocean might have stayed open for a billion years, warmed by greenhouse effects under a thick primordial atmosphere. A billion years is plenty of time for life to evolve. Eventually the ocean surface froze over to form an icy crust, and at the ocean’s base complex high-pressure forms of ice formed a deep solid layer enclosing the silicate core. Ice above and below, but still the liquid ocean persisted between, ammonia-rich water, very alkaline, very viscous. And in that deep ocean had emerged a unique kind of life, adapted to its strange environment, based on chemical bonds between carbon and nitrogen-hydrogen chemical groups rather than carbon-oxygen, using ammonia as its solvent rather than water: ‘ammono life’, the specialists call it.

‘Yes, a third kind of life,’ Miriam said. ‘One unknown elsewhere in the Solar System so far as I know. So here on Titan you have a junction of three entirely different domains of life: native ammono life in the mantle ocean,
CHON
life in the crater lakes blown in from the inner System, and the silane lilies wafting in from Triton and the outer cold. Incredible.’

‘More than that,’ Harry said tinnily. ‘Michael, that tube-fish of yours is not a methanogen – it doesn’t create methane – but it’s full of it. Methane is integral to its metabolism, as far as I can see from the results you sent me. It even has methane in its flotation bladders.’

Miriam looked at the tube-fish blindly chewing at the ice walls. ‘Right. They collect it somehow, from some source deep in the ocean. They use it to float up here. They even nibble the cryovolcano vent walls, to keep them open. They have to be integral to delivering the methane from the deep ocean sources, up through the crevices in the ice cap and to the atmosphere. So you have the three domains not just sharing this moon but cooperating in sustaining its ecology.’

Harry said, ‘Quite a vision. And as long as they’re all stupid enough, we might make some money out of this damn system yet.’

Miriam let go of her tube-fish, like freeing a bird; it wriggled off into the dark water. ‘You always were a realist, Harry.’

I thought I saw blackness below us, in the outer glimmer of Poole’s suit lamps. I called, ‘How deep is this ice crust, before we get to the mantle ocean?’

‘Around thirty-five kilometres,’ Harry replied.

‘And how deep are we now?’

‘Oh, around thirty-five kilometres.’

Michael Poole gasped. ‘Lethe. Grab hold, everybody.’

It was on us at once: we had almost passed through this vent we had followed all the way down from the cryovolcano mouth at the surface, this passage right through the ice crust of Titan. I gripped the net and shut my eyes.

The spider let go of the wall and dropped into the void. As we passed out of the vent, through the roof of ice and into the mantle beneath, I felt the walls recede from me, a wash of pressure, a vast opening-out. And we fell into the dark and the cold.

12

Now that the walls were gone from under its limbs I could feel that the spider was
swimming
, or perhaps somehow jetting, ever deeper into that gloopy sea, while the three of us held on for our lives.

Looking up I saw the base of Titan’s solid crust, an ice roof that covered the whole world, glowing in the light of Poole’s lamps but already receding. And I thought I saw the vent from which we had emerged, a much eroded funnel around which tube-fish swam languidly. Away from the walls I could more easily see the mechanics of how the fish swam; lacking fins or tails they seemed to twist through the water, a motion maybe suited to the viscosity of the medium. They looked more like bloated bacteria than fish.

Soon we were so far beneath the ice roof that it was invisible, and we three and the spider that dragged us down were a single point of light falling into the dark.

And then Poole turned off his suit lamps!

I whimpered, ‘Lethe, Poole, spare us.’

‘Oh, have a heart,’ Miriam said, and her own suit lit up. ‘Just for a time. Let him get used to it.’

I said, ‘Get used to what? Falling into this endless dark?’

‘Not endless,’ Poole said. ‘The ocean is no more than – how much, Harry?’

‘Two hundred and fifty kilometres deep,’ Harry said, mercifully not presenting a Virtual to us. ‘Give or take.’

‘Two hundred and fifty . . . How deep are you intending to take us, Poole?’

‘I told you,’ Michael Poole said grimly. ‘As deep as we need to go. We have to retrieve that GUTengine, Emry. We don’t have a choice – simple as that.’

‘And I have a feeling,’ Miriam said bleakly, ‘now we’re out of that vent, that we may be heading all the way down to the bottom. It’s kind of the next logical choice.’

‘We’ll be crushed,’ I said dismally.

‘No,’ Harry Poole piped up. ‘Look, Jovik, just remember Titan isn’t a large world. The pressure down there is only about four times what you’d find in Earth’s deepest oceans. Five, tops. Your suit is over-engineered. Whatever it is that kills you, it won’t be crushing.’

‘How long to the bottom, then?’

Harry said, ‘You’re falling faster than you’d think, given the viscosity of the medium. That spider is a strong swimmer. A day, say.’

‘A day!’

Miriam said, ‘There may be sights to see on the way down.’

‘What sights?’

‘Well, the tube-fish can’t exist in isolation. There has to be a whole ammono ecology in the greater deeps.’

My imagination worked overtime. ‘Ammono sharks. Ammono whales.’

Miriam laughed. ‘Sluggish as hell, in this cold soup. And besides, they couldn’t eat you, Jovik.’

‘They might spit me out but I’d rather they didn’t try at all. And even if we survive – even if we do find our damn GUTengine down there on the ice – how are we supposed to get back out of here?’

Poole said easily, ‘All we need to do is dump our ballast, our bags of ice, and we’ll float up. We don’t need to bring up the GUTengine, remember, just use it to recharge the suits.’

Miriam said, ‘A better option might be to hitch a ride back with another spider.’

‘Right. Which would solve another problem,’ Poole said. ‘Which is to find a cryovolcano vent to the surface. The spiders know the way, evidently.’

Harry said, ‘And even without the spiders I could guide you. I can see you, the vent mouths, even the GUTengine. This neutrino-radar technology was worth the money it cost. There’s no problem, in principle.’

At times I felt less afraid of the situation than of my companions, precisely because of their lack of fear.

Miriam fetched something from a pack at her waist, I couldn’t see what, and glanced at Poole. ‘Jovik’s not going to survive a descent lasting a day. Not in the dark.’

Poole looked at me, and at her. ‘Do it.’

‘Do what?’

But I had no time even to flinch as she reached across, and with expert skill pressed a vial into a valve in the chest of my exosuit. I felt a sharp coldness as the drug pumped into my bloodstream, and after that only a dreamless sleep, cradled in the warmth of my cushioned suit.

So I missed the events of the next hours, the quiet times when Poole and Miriam tried to catch some sleep themselves, the flurries of excitement when strange denizens of Titan’s ammono deep approached them out of the dark.

And I missed the next great shock suffered by our dysfunctional little crew when the base of Titan’s underground ocean, an ice floor three hundred kilometres beneath the surface, at last hove into view. The strange landscape of this abyssal deep, made of folded high-pressure ices littered by bits of meteorite rock, was punctured by vents and chasms, like an inverted mirror image of the crust far above us.
And the spider we rode did not slow down.
It hurled itself into one of those vents, and once more its limbs began to clatter down a wall of smooth rock-ice.

Harry warned Miriam and Poole that this latest vent looked as if it penetrated the whole of this inner layer of core-cladding ice – Ice
VI
, laced by ammonia dihydrate – a layer another five hundred kilometres deep. At the base of this vent there was only Titan’s core of silicate rocks, and there, surely, the spiders’ final destination must lie.

There was nothing to be done but to endure this extension of the ride. It would take perhaps a further day. So Poole and Miriam allowed the spider to drag us down. More tube-fish, of an exotic high-pressure variety, grazed endlessly at the icy walls. Miriam popped me another vial to keep me asleep, and fed me intravenous fluids. Harry fretted about the exhaustion of our power, and the gradual increase of pressure; beneath a column of water and ice hundreds of kilometres deep, we were approaching our suits’ manufactured tolerance. But they had no choice but to continue, and I, unconscious, had no say in the matter.

When the ride was over, when the spider had at last come to rest, Miriam woke me up.

I was lying on my back on a lumpy floor. The gravity felt even weaker than it had on the surface. Miriam’s face hovered over me, illuminated by suit lamps. Smiling, she said, ‘Jovik. Look what we found.’

I sat up. I felt weak, dizzy, hungry. Beside me, in their suits, Miriam and Poole sat watching my reaction. Then I remembered where I was and the fear cut in.

I looked around quickly. Even by the glow of the suit lamps I could not see far. The murkiness and floating particles told me I must be still immersed in the water of Titan’s deep ocean. I saw a roof of ice above me – not far above, a hundred metres or so. Below me was a surface of what looked like rock, dark and purple-streaked. I was in a sort of ice cavern, then, whose walls were off in the dark beyond our bubble of light. I learned later that I was in a cavern dug out beneath the lower icy mantle of Titan, between it and the rocky core,
eight hundred kilometres
below the icy plains where I had crash-landed days before. Around us I saw ice spiders, toiling away at their own enigmatic tasks, and bits of equipment from the gondola, chopped up, carried here and deposited. There was the GUTengine! My heart leapt; perhaps I would yet live through this.

But even the engine wasn’t what Miriam was smiling about. She repeated, ‘Look what we found.’

I looked.

Set in the floor, in this rocky core of a world, was a hatch.